BACKGROUND CONTEXT: There has been recent enthusiasm regarding the potential positive effects of statins on bone. Statins vary in their ability to influence bone activity. Simvastatin has been shown in experimental models to stimulate bone acting growth factors and enhance bone formation. PURPOSE: The potential efficacy of Simvastatin in enhancing spinal fusion was evaluated in a rabbit posterolateral intertransverse process fusion model. STUDY DESIGN/SETTING: Posterior lumbar intertransverse process spinal fusion performed on New Zealand White rabbits. PATIENT/STUDY SAMPLE: 44 New Zealand White rabbits. OUTCOME MEASURES: Spinal fusion as determined by manual palpation testing and fine detail radiography. Bone fusion mass volume and density as determined by CT scan imaging. METHODS: Forty-four New Zealand White rabbits underwent posterolateral intertransverse process spine fusion using autogenous iliac crest bone graft. Simvastatin was administered orally in 20 animals and the serum lipid profile quantified in test and control animals. The animals were euthanized 9 weeks following index surgery and the lumbar spine was harvested. Spinal fusion was determined by manual palpation testing and fine detail radiography. The volume and density of the bone fusion mass was quantified by computed tomography. RESULTS: Drug treatment for 9 weeks caused a reduction in serum lipid biochemical markers when compared with controls. The spinal fusion rate, as judged by manual palpation testing (13.0% control group, 16.6% Simvastatin group) and fine detail radiography, was not significantly different comparing treatment with control animals. Accordant with the assessment of spinal fusion, there was no statistically significant effect on the volume of the fusion mass (1,224.7+/-98.7 mm(3) in the control group and 1,075.9+/-66.3 mm(3) in the Simvastatin group), the density of bone in the lumbar spine or that in the formed fusion mass. CONCLUSIONS: Systemic use of Simvastatin caused a reduction in lipid biochemical parameters in treated animals. Successful spinal fusion as judged by manual palpation testing and fine detail radiography was not significantly different in treated versus untreated animals. The bone volume density of the formed fusion mass was not significantly different in treated versus untreated animals. There did not appear to be a significant advantage or disadvantage to the use of Simvastatin rabbit posterolateral spinal fusion. The potential positive effects of statins on bone require further study. PMID: 16825044 [PubMed - indexed for MEDLINE]  Full Article

BACKGROUND CONTEXT: Recombinant human bone morphogenetic protein-2 (rh-BMP2) has become popular for augmenting spine fusion in the lumbar and cervical spine. Concerns exist, however, over bone morphogenetic protein (BMP)-stimulated soft-tissue swelling and bone growth stimulation in areas where bone is not desired, especially as the material "leaks" into such spaces. The most detrimental effects of such leakage might be airway compromise, while heterotopic bone formation into the spinal canal has been reported in animal and human studies. Fibrin glue has been used as a carrier of many osteoinductive materials; however, its efficacy at modulating the clinical effects of BMP are not known. The amorphous nature of fibrin glue makes it a candidate to control diffusion of BMP and possibly limit bone formation by limiting BMP diffusion to areas where such bone is not desired. PURPOSE: To evaluate the use of fibrin glue to limit BMP diffusion and BMP-stimulated bone growth. STUDY DESIGN/SETTING: This is an in vitro basic science study and an in vivo prospective randomized animal study. STUDY SAMPLE: Eighteen Lewis rats. OUTCOME MEASURES: In vitro study: Enzyme-linked immunosorbent assay measurement of rh-BMP2 concentration in saline. In vivo study: At day 60, rats were evaluated for neurologic deficits before sacrifice. Spines were harvested, and the following studies were performed: 1) manual testing for fusion and bone growth; 2) X-ray evaluation; 3) Micro-computed tomography (micro-CT) scans. METHODS: In vitro study: Collagen sponges soaked with BMP at two different concentrations were incubated in saline solution with and without encapsulation by fibrin glue. Saline BMP concentrations were measured at consecutive time points. In vivo study: A rat fusion model using rh-BMP2 for fusion has been developed and tested with resultant100% fusion in over 100 rats. Lewis rats were divided into two groups and treated as follows: I: Exposure of L4-L5 transverse processes, decortication, and placement of BMP sponge in the lateral intertransverse space. II: Exposure and decortication as above and placement of fibrin glue before BMP sponge placement. RESULTS: In vitro study: Peak rh-BMP2 concentrations in saline were 20% and 45% of the maximum possible for fibrin glue encapsulated sponges and controls, respectively, with a more gradual increase to peak concentration in samples encapsulated in fibrin glue. In vivo study: No rats exhibited any neurologic deficits. X-rays revealed at least partial bone formation in all rats. Manual testing of intertransverse fusion spines revealed 100% fusion in rats treated with BMP only, whereas rats treated with fibrin glue before placement of BMP sponges revealed only one possible fusion. Posterior-lateral bone formation was present on X-ray in both groups, and micro-CT imaging revealed bridging bone from transverse processes to the BMP-stimulated bone in the control groups. In spines treated with fibrin glue before rh-BMP2 placement, bone formation could still be seen within the soft tissues; however, bridging bone connecting to the transverse processes was either significantly decreased or not present. CONCLUSIONS: Fibrin glue can limit rh-BMP2 diffusion. Also, because it limited bone formation at the transverse processes, it can be inferred that fibrin glue can limit bone formation when used to separate areas of desired bone formation from areas where bone formation is not desired. PMID: 16825045 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: Enzyme-linked immunosorbent assay was used to detect bone morphogenetic proteins (BMPs) 2, 4, and 7 in 9 commercially available ("off the shelf") demineralized bone matrix (DBM) product formulations using 3 different manufacturer's production lots of each DBM formulation. OBJECTIVES: To evaluate and compare the quantity of BMPs among several different DBM formulations (inter-product variability), as well as examine the variability of these proteins in different production lots within the same DBM formulation (intra-product variability). SUMMARY OF BACKGROUND DATA: DBMs are commonly used to augment available bone graft in spinal fusion procedures. Surgeons are presented with an ever-increasing variety of commercially available human DBMs from which to choose. Yet, there is limited information on a specific DBM product's osteoinductive efficacy, potency, and constancy. METHODS: There were protein extracts from each DBM sample separately dialyzed 4 times against distilled water at 4 degrees C for 48 hours. The amount of BMP-2, BMP-4, and BMP-7 was determined using enzyme-linked immunosorbent assay. RESULTS.: The concentrations of detected BMP-2 and BMP-7 were low for all DBM formulations, only nanograms of BMP were extracted from each gram of DBM (20.2-120.6 ng BMP-2/g DBM product; 54.2-226.8 ng BMP-7/g DBM). The variability of BMP concentrations among different lots of the same DBM formulation, intra-product variability, was higher than the variability of concentrations among different DBM formulations, inter-product variability (coefficient of variation range BMP-2 [16.34% to 76.01%], P < 0.01; BMP-7 [3.71% to 82.08%], P < 0.001). BMP-4 was undetectable. CONCLUSIONS: The relative quantities of BMPs in DBMs are low, in the order of 1 x 10(-9) g of BMP/g of DBM. There is higher variability in concentration of BMPs among 3 different lots of the same DBM formulation than among different DBM formulations. This variability questions DBM products' reliability and, possibly, efficacy in providing consistent osteoinduction. PMID: 16721289 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: An in vitro and in vivo study. OBJECTIVE: To evaluate the ability of fibrin glue to limit diffusion of recombinant human bone morphogenetic protein (rhBMP)-2 and its ability to protect spinal nerves from rhBMP-2 stimulated bone growth. SUMMARY OF BACKGROUND DATA: Studies have shown bone morphogenetic protein (rhBMP-2) stimulated bone growth can encroach on the spinal canal and nerves, causing neural compression. More recently, rhBMP-2 use in the cervical spine has been associated with life-threatening swelling. Fibrin glue has been used as a biologic carrier but has not been evaluated for its ability to limit rhBMP-2. METHODS: In phase 1 of the study, rhBMP-2 soaked absorbable collagen sponges (ACS) were encapsulated in fibrin glue and immediately incubated in physiologic lactated ringers solution at 38 degrees C. Samples of solution were tested for rhBMP-2 concentration. In phase 2 of the study, rats were surgically treated with laminectomy and placement of rhBMP-2/ACS versus laminectomy and placement of fibrin glue before placement of rhBMP-2/ACS. After 8 weeks, animals were euthanized and imaged using micro-computerized tomography. RESULTS: The diffusion study showed a significant limitation in rhBMP-2 diffusion when encapsulated in fibrin glue. The laminectomy study revealed blockage of bone formation by fibrin glue and protection of the spinal canal. CONCLUSIONS: Fibrin glue can limit the diffusion of rhBMP-2, and, thus, it can be used to help protect the spinal canal and nerve roots from rhBMP-2 stimulated bone growth. PMID: 16688032 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: This is a prospective cohort study examining the results and radiographic characteristics of anterior lumbar interbody fusion (ALIF) using femoral ring allografts (FRAs) and recombinant human bone morphogenetic protein-2 (rhBMP-2). This was compared to a historical control ALIF using FRAs with autologous iliac crest bone graft (ICBG). OBJECTIVE: To determine whether the use of rhBMP-2 can enhance fusion ALIF with stand-alone FRAs. SUMMARY OF BACKGROUND DATA: ALIF is a well-accepted procedure in reconstructive spine surgery. Advances in spinal surgery have produced a multitude of anterior interbody implants. The rhBMP-2 has promoted fusion in patients undergoing ALIF with cages and threaded allograft dowels. The FRA still remains a traditional alternative for anterior support. However, as a stand-alone device, the FRA has fallen into disfavor because of high rates of pseudarthrosis. With the advent of rhBMP-2, the FRA may be more attractive because of its simplicity and remodeling potential. It is important to understand the implications when rhBMP-2 is used with such structural allografts. METHODS: A total of 36 consecutive patients who underwent ALIF with stand-alone FRAs by a single surgeon (E.G.D.) at 1 institute were included. A cohort of 9 consecutive patients who received FRAs filled with rhBMP-2 was followed prospectively. After noticing suboptimal results, the senior author terminated this method of lumbar fusion. A total of 27 prior consecutive patients who received FRAs filled with autogenous ICBG were used for comparison. Analyzing sequential radiographs, flexion-extension radiographs, and computerized tomography with multiplanar reconstructions determined nonunions. Minimum follow-up was 24 months. RESULTS: Pseudarthrosis was identified in 10 of 27 (36%) patients who underwent stand-alone ALIF with FRAs and ICBG. Nonunion rate was higher among patients who received FRAs with rhBMP-2 (i.e., 5 of 9 [56%]). Statistical significance was not established because of the early termination of the treatment group (P > 0.3). Of interest, radiographs and computerized tomography revealed early and aggressive resorption of the FRAs when used with rhBMP-2. This preceded graft fracture and even disintegration, resulting in instability and eventual nonunion. CONCLUSION: The use of rhBMP-2 did not enhance the fusion rate in stand-alone ALIF with FRAs. In fact, the trend was toward a higher nonunion rate with rhBMP-2, although this was not significant with the numbers available. This result appears to be caused by the aggressive resorptive phase of allograft incorporation, which occurs before the osteoinduction phase. PMID: 16648733 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: Prospective cohort study of 52 patients who had undergone artificial lumbar disc replacement. OBJECTIVES: To evaluate the implantation accuracy of prosthesis positioning, subsequent facet joint changes and prosthesis migration, and the clinical consequences of implant position. SUMMARY OF BACKGROUND DATA: Accuracy of spinal prosthesis implantation has not been evaluated rigorously, especially with a mini-incision approach. It is unknown if the inexact placement of a mobile device in the spine has any biomechanical, radiographic, or clinical repercussions. METHODS: A total of 52 consecutive patients were treated using standard methods of disc implantation with an intervertebral prosthesis. Computed tomography scans were performed within 3 days and again at 6 to 24 months. An independent radiologist analyzed the images for prosthesis position, rotation, migration, and facet changes. Results were compared with clinical outcome, measured by the Visual Analog Scale and Oswestry Disability Index. RESULTS: Deviation of the prosthesis from the center position was under 1.2 mm, and rotation off of midline was under 12 degrees. Follow-up CT scans showed no migration or facet changes. Regression analysis showed no correlation of prosthesis position with clinical outcome. CONCLUSIONS: Current prosthetic disc implantation methods, with minimally invasive access techniques, are relatively accurate. Although there can be deviation of the prosthesis from ideal placement, no repercussions were attributable. PMID: 16622387 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: A retrospective study of patients who underwent 1-3-level kyphoplasty procedures at a single institute. OBJECTIVE: To examine and compare the effects of single and multilevel kyphoplasty procedures on local versus overall sagittal alignment of the spine. SUMMARY OF BACKGROUND DATA: Cement augmentation has been a safe and effective method in the treatment of symptomatic vertebral compression fractures (VCFs). In addition to providing rapid pain relief, balloon tamp kyphoplasty has reduced acute fractures, allowed controlled cement placement under lower pressure, and resulted in improvement of deformity. The restoration of normal overall spinal sagittal alignment in the elderly patient with a VCF and kyphotic deformity has obvious benefits. Although significant correction of local kyphosis (fractured vertebra) has been reported in the literature, to our knowledge, there have been no reports on whether this leads to an improved overall sagittal alignment. METHODS: A total of 65 consecutive patients with symptomatic VCFs who underwent 1-3-level kyphoplasty procedures were included in the study. Preoperative and postoperative radiographs were analyzed to quantify local and overall spinal sagittal alignment correction. Preoperative and postoperative vertebral heights at the fractured levels were also measured and categorized into anterior, middle, or posterior vertebral heights. RESULTS: Measurements revealed that kyphoplasty reduced local kyphotic deformity at the fractured vertebra by an average of 7.3 degrees (63% of preoperative kyphosis). This result did not translate to similar correction in overall sagittal alignment. In fact, angular correction decreased to 2.4 degrees (20% of preoperative kyphosis at fractured level) when measured 1 level above and below. The angular correction further decreased to 1.5 degrees and 1.0 degrees (13% and 8% of preoperative kyphosis at fractured level), respectively, at spans of 2 and 3 levels above and below. Average height gain was highest in the middle of the vertebral body (39% increase) compared to the anterior or posterior edges (19% and 3% increases, respectively). With multilevel kyphoplasty procedures, higher angular gains were seen over more vertebrae compared to the 7.3 degrees for a single-level kyphoplasty: 7.8 degrees over 2 levels and 7.7 degrees over 3 levels for 2 and 3-level kyphoplasty procedures, respectively. Kyphoplasty was able to achieve higher angular reduction in thoracic versus lumbar fractures (8.5 vs. 6.4 degrees, P < 0.01). The angular correction was also better maintained over adjacent segments in the thoracic spine. CONCLUSION: The majority of kyphosis correction by kyphoplasty is limited to the vertebral body treated. The majority of height gained after kyphoplasty occurs in the midbody. Higher correction over longer spans of the spine can be achieved with multilevel kyphoplasty procedures, in proportion to the number of levels addressed. Notwithstanding its well-published clinical efficacy, it is unrealistic to expect a 1 or 2-level kyphoplasty to improve significantly the overall sagittal alignment after VCFs. PMID: 16481954 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: A retrospective review of 33 consecutive patients treated with posterior fusion and selective nerve root decompression for the treatment of pseudarthrosis following anterior cervical discectomy and fusion. OBJECTIVES: Use standardized outcome measures to evaluate the results of posterior fusion with selective nerve root decompression as a treatment option for symptomatic pseudarthrosis of the cervical spine. SUMMARY OF BACKGROUND DATA: Pseudarthrosis after anterior cervical discectomy and fusion has been recognized as a cause of continued cervical pain and unsatisfactory outcomes. Debate continues as to whether a revision anterior approach or a posterior fusion procedure is the best treatment for symptomatic cervical pseudarthrosis. To our knowledge, standardized outcome measures have not been used to evaluate the results of either surgical treatment option; therefore, it is difficult to evaluate outcomes in these patients, let alone compare surgical treatment options. Data on fusion rates in these two surgical treatment groups suggest a trend of a higher fusion rate with utilization of a posterior revision procedure, but the largest study to date includes the study of only 19 patients treated with a posterior fusion. METHODS: Thirty-three consecutive patients with symptomatic pseudarthrosis following anterior cervical discectomy and fusion were treated with selective nerve root decompression and posterior fusion using iliac crest or local bone graft as well as posterior wiring and/or lateral mass plating. The average follow-up period was 46 months (range, 20-86 months). Patients were assessed using physical examination, flexion-extension lateral radiographs, and standardized outcome measures including the SF-36, Arthritis Impact Measurement Scales 2, and Cervical Spine Outcomes Questionnaire. RESULTS: All 33 patients (100%) demonstrated a solid fusion at their most recent follow-up, and all 33 patients noted significant improvement in their preoperative symptoms. No difference in fusion status was noted between those treated with iliac crest versus patients treated with local bone graft--all had a solid fusion; 72% of the patients were satisfied with the result of their surgery. Cervical Spine Outcomes Questionnaire pain scales demonstrated 52% of patients reported mild or nopain at follow-up, whereas 20% described their pain as "discomforting" and 28% of the patients continued to report moderate to severe pain. CONCLUSIONS: This is the first study to our knowledge to use standardized outcome measures to assess clinical outcome in patients treated with posterior fusion for pseudarthrosis after anterior cervical discectomy and fusion. Patients and surgeons need to understand the potential for success with this revision procedure but also be aware of the relatively high rate of continued moderate to severe pain observed in this patient population even after a solid fusion is achieved. All of the patients in this study fused with a single posterior fusion procedure, further supporting the relatively higher fusion rates observed in the literature using posterior fusion as a treatment for cervical pseudarthrosis. Our results also support the ability of surgeons to use local bone graft without iliac crest in a posterior fusion for cervical pseudarthrosis and therefore avoid the morbidity associated with iliac crest bone graft harvest. PMID: 16261120 [PubMed - indexed for MEDLINE]  Full Article

BACKGROUND: Foot problems are common in patients with Marfan syndrome because of the ligamentous laxity that affects the weightbearing joints most. Such patients frequently are seen by their general practitioners or podiatrists. Educating primary health care providers about a metatarsal index, if it is sufficiently sensitive and specific, may help patients get early and appropriate workup for connective tissue disorders. METHODS: A metatarsal equivalent to the metacarpal index (MCI) in the hand was evaluated as a diagnostic tool for Marfan syndrome (and possibly other connective tissue disorders). Fifty-six patients were studied. Sixteen had a genetic diagnosis of Marfan syndrome. There were 20 controls each for the MCI and the metatarsal index (MTI). Hand and foot radiographs were reviewed. RESULTS: The average MCI in patients with Marfan syndrome was 9.8 compared to 7.6 in the control group (p < 0.0005). The average MTI was 12.7 and 9.8, respectively (p < 0.0005). An MCI value of 8.5 and an MTI value of 10.5 had the best statistical profiles (combination of sensitivity and specificity) in diagnosing Marfan syndrome in our study population. CONCLUSION: The MTI as a screening tool for Marfan syndrome is as effective as, if not more than, the well-recognized MCI. PMID: 16221462 [PubMed - indexed for MEDLINE]  Full Article

The much-awaited clinical use of lumbar artificial discs has begun in the United States. The United States Investigational Device Exemption (US IDE) clinical trial of the ProDisc-II prosthetic disc (Synthes, Paoli, PA) was recently completed, with all indications that it meets or surpasses the test of equivalence against fusion controls. This is a review of the clinical performance of the ProDisc-II artificial disc and includes an interim report from the US IDE trial at one site. PMID: 15950690 [PubMed - indexed for MEDLINE]  Full Article

BACKGROUND CONTEXT: With the number of anterior lumbar procedures expected to increase significantly over the next few years, it is important for spine surgeons to have a good understanding about the incidence of vascular complications during these operations. PURPOSE: To determine the incidence of vascular injury in 1,315 consecutive cases undergoing anterior lumbar surgery at various levels from L2 to S1. STUDY DESIGN/SETTING: Patients undergoing anterior lumbar surgery were studied. PATIENT SAMPLE: A total of 1,310 consecutive patients undergoing 1,315 anterior lumbar procedures between August 1997 and December 2002 were included in the study. OUTCOME MEASURES: All patients were evaluated for incidence of vascular injury during and immediately after surgery. METHOD: A concurrent database was maintained on all these cases. All the patients had distal pulse evaluation preoperatively. Patients with venous injuries were further analyzed to determine location and extent of injury, amount of blood loss, completion of the procedure and postoperative sequelae. Patients with pulse deficits or evidence of ischemia during or immediately after surgery were further analyzed in particular in relation to demographic, preoperative variables and management. RESULTS: Six patients were identified as having left iliac artery thrombosis (0.45%), and 19 had major vein lacerations (1.4%). CONCLUSION: This study shows that the incidence of vascular injury is relatively low (25 in 1,315 or 1.9%). Because only five of these patients experienced significant sequelae from the approach, it appears that anterior lumbar surgery is quite safe, although it must be carried out with utmost respect for the vessels to avoid possible catastrophic outcomes. PMID: 15246301 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: The accuracy and interobserver agreement of fine detail radiography and computed tomography (CT) determination of spinal fusion were evaluated in an established animal spine fusion model. OBJECTIVE: To determine the accuracy and interobserver agreement of radiographic determinations of spinal fusion in rabbit posterolateral spine fusion. SUMMARY OF BACKGROUND DATA: The rabbit posterolateral intertransverse process spine fusion model is an established animal model for evaluating bone graft alternatives for spinal fusion. However, little is known regarding the accuracy and interobserver agreement of radiographic determinations of spondylodesis in this model. METHODS: Forty-two New Zealand White rabbits underwent posterolateral spinal fusion. The animals were killed at 9 weeks and the lumbar spine harvested. Manual manipulation, fine detail radiography, and CT images were used to assess spinal fusion. RESULTS: Using manual palpation testing as the standard by which to assess fusion, there was high sensitivity and negative predictive value for both radiographic methods. Positive predictive value, however, was poor (26% fine detail radiography, 61% CT scan). CT correlated better with manual palpation testing when compared with fine detail radiographs. There was substantial interobserver agreement of successful fusion using CT scan imaging (kappa = 0.63) and moderate interobserver agreement radiographs (kappa = 0.52). CONCLUSIONS: Both radiographic techniques used in the study recorded high sensitivity and negative predictive value. However, positive predictive value was poor, especially with fine detail radiographs. Nevertheless, CT with reformatted images did appear to be superior to fine detail radiographs in accurately identifying nonunions in this animal model. PMID: 15187630 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: Retrospective study with independent evaluation of patient outcomes approximately 1 year post-intradiscal electrothermal therapy (IDET). OBJECTIVE.: To assess functional status, symptoms, and subsequent treatments of patients treated with IDET. SUMMARY OF BACKGROUND DATA: IDET was introduced as a procedure for discogenic pain. Several studies reported improvement in >70% of patients. METHODS: Seventeen physicians referred 60 patients. Each patient had a positive discogram and had been treated with IDET. Patients were contacted approximately 1 year post-IDET, answered a telephone interview, and completed a self-administered questionnaire. Overall patient satisfaction, pain, functional and work status, analgesic usage, and subsequent treatments were noted. Kaplan-Meier survival curve was generated to predict the percentage that would undergo lumbar surgery after IDET. RESULTS: Average age was 40 years (range 25-64 years) with 66% males and 34% females. Of the 44 patients who responded, 6 patients had a lumbar surgery within 1 year. Their outcomes were excluded from descriptive analysis; 97% continued to have back pain, 11 (29%) reported more pain post versus pre-IDET, 15 (39%) had less pain, and 11 (29%) reported no change; 11 (29%) reported using more pain medication post-IDET, 10 (26%) used the same, 12 (32%) used less, and 5 (13%) used none; 19 (50%) were dissatisfied with IDET, 14 (37%) were satisfied, and 5 (13%) were undecided; 20 (53%) would have the procedure again, 12 (31%) would not, and 6 (16%) were unsure. Most patients wore a brace >6 hours/day after surgery (duration 1-15 months). Sixteen (42%) were employed full-time pre-IDET and 11 (29%) were employed full-time post-IDET. CONCLUSION: At 1-year post-IDET, half of patients were dissatisfied with their outcome. The percentage of patients on disability remained constant. The estimated proportion of patients undergoing fusion was predicted to be 15% at 1 year and 30% at 2 years. PMID: 15087797 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: A retrospective outcomes study. OBJECTIVES: To examine the outcome following adjacent two-level lumbar discectomy using both surgeon-based evaluation criteria and validated patient-based quality of life instrument (SF-36). SUMMARY OF BACKGROUND DATA: Lumbar discectomies have documented success rates between 49% and 98% for single-level procedures. However, no prior study has specifically examined the outcome following adjacent two-level lumbar discectomy in a large series of patients. METHODS: This study analyzed 55 patients with a minimum 2-year follow-up. All patients underwent adjacent two-level lumbar discectomy for radicular pain attributable to nerve root impingement at the corresponding levels. The patients were divided into two diagnostic groups based on their preoperative radiographic studies. Patients with two-level adjacent posterolateral lumbar disc herniations without concomitant osseous degenerative changes at the same levels constituted Group 1 (22 patients). Patients with associated osseous degenerative changes at the same levels made up Group 2 (33 patients). The patients' clinical outcome was assessed using the MacNab classification and SF-36 questionnaire. RESULTS: The average duration of follow-up was 41 months (range 24-96 months). The group consisted of 35 males and 20 females with average age of 49 years (range 19-82 years). Excellent results were observed in 49%, good in 20%, fair in 15%, and poor in 16%. However, patients in Group 1 have 86% excellent/good results, whereas patients in Group 2 have 57% excellent/good results. Overall, 15% of the patients required reoperation and subsequent spinal fusion. Analysis of the SF-36 scores revealed significant differences based on patient's diagnostic grouping as well. Patients in Group 1 have physical and mental summary scores comparable with age- and sex-adjusted population norms and significantly higher than those in Group 2 (P < 0.01). CONCLUSIONS: Two-level discectomy is an effective treatment with clinical outcome comparable with single-level discectomy. Patients with posterolateral disc herniations and definitive radiculopathy without osseous degenerative changes at the same levels have better clinical outcome and quality of life scores compared with those patients having concomitant degenerative arthritis at the same levels. Patients having two-level discectomy may be at increased risk of requiring subsequent lumbar fusion compared with those with single-level discectomy. PMID: 14722421 [PubMed - indexed for MEDLINE] Full Article

To determine the incidence of left iliac artery thrombosis (LIAT), a prospective database was maintained on 1315 patients undergoing anterior lumbar surgery (ALS) between August 1997 and December 2002. All had distal pulse evaluation preoperatively. In the last 629 cases pulse oxymetry was used to monitor the distal circulation during and after surgery. Patients with pulse deficits or evidence of ischemia after surgery were further analyzed. Six patients were identified with LIAT (0.45%). Five were females and one was male, with ages ranging from 35 to 56 years. All had exposure at the L4-5. Five were diagnosed at surgery and one in the recovery room after posterior surgery. All except one had strong, palpable preoperative pulses. Pulse oxymetry confirmed the diagnosis in two patients, in whom it was not clinically evident. Four had successful thrombectomy; one had a femoro-femoral bypass and one had an axillo-femoral bypass. Two developed compartment syndrome. None had calcifications on preoperative X-rays. LIAT is an uncommon complication of ALS. Early identification and management can avoid long-term complications. Pulse oxymetry helps in its timely identification. Patients undergoing exposure at L4-5 and females are at greater risk. PMID: 14712382 [PubMed - indexed for MEDLINE]  Full Article

Few data are available to evaluate approach-related differences in perioperative complications with lumbar interbody fusion devices. Complications occurring in the intraoperative and immediate postoperative period were identified and categorized for 31 consecutive posterior lumbar interbody fusions (PLIFs) and 88 consecutive anterior lumbar interbody fusions (ALIFs). In this study, all lumbar interbody fusions were conducted with threaded cylindrical devices as stand-alone internal fixation devices. Multivariate analysis was used to account for potential covariates and identify factors associated with an increased complication risk. Twenty-two percent of the patients had a perioperative complication. The relative risk of having a perioperative complication was 4.75 times higher for the PLIF group. All intraoperative complications occurred in the PLIF group. The relative risk of having a major postoperative complication was 6.8 times higher in the PLIF group than the ALIF group. Anterior approached patients tended to have visceral (ileus, 6%) and vascular (deep venous thrombosis, 2%) complications. In the posterior group, complications were neurologic and dura related (pseudomeningocele, 16%; epidural hematoma, 3%) and occurred most frequently in patients that had had previous posterior lumbar surgery (31% with major complication). PMID: 14657745 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: Posterolateral spinal fusion with allogeneic demineralized bone graft-hyaluronan putty in addition to autogenous iliac crest bone graft in a rabbit model. OBJECTIVES: To determine the potential efficacy of demineralized bone graft-hyaluronan putty as a bone graft enhancer. SUMMARY OF BACKGROUND DATA: Autograft bone is the material of choice for posterolateral lumbar intertransverse process fusion. Bone graft alternatives such as demineralized bone matrices that can be used as graft extenders, enhancers, or substitutes continue to be developed. METHODS: One hundred New Zealand white rabbits underwent bilateral posterolateral spinal fusion with autogenous iliac crest bone graft or bone graft with allogeneic rabbit demineralized bone graft-hyaluronan putty. The rabbits were killed 9 weeks later, and the lumbar spines were removed. Manual manipulation and fine detail radiography were used to assess spinal fusion, and computed tomographic images were used to quantify the volume of the fusion mass. RESULTS: In comparison with autograft bone alone, the fusion rates were greater when demineralized bone graft-hyaluronan putty was used as an adjunct to autogenous bone. Furthermore, the radiographic fusion rate was greater when demineralized bone graft-hyaluronan putty was used in a 2:1 ratio to autograft bone in comparison with a 1:1 ratio (P = 0.001). The addition of demineralized bone graft-hyaluronan putty to autograft bone was found to increase mineralized bone volume in a ratio-dependent manner (P < 0.05). CONCLUSIONS: Allogeneic demineralized bone matrix-hyaluronan putty enhances rabbit posterolateral spine fusion when used as an adjunct to autogenous bone graft. This new formulation of demineralized bone matrix may facilitate greater bone formation and successful fusion. PMID: 14595160 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: Multicenter prospective randomized study of artificial disc replacement (ProDisc) versus circumferential fusion (standard of care) for one- and two-level degenerative disc disease. This is an interim analysis on patients seen at the Spine Institute Saint John's Health Center, Santa Monica, California. OBJECTIVES: To evaluate early pain and functional outcomes of patients treated with disc replacement or fusion and to assess the capacity of this intervertebral disc replacement for preserving motion in the lumbar spine. SUMMARY OF BACKGROUND DATA: Disc replacement is intended to reduce pain via removal of the diseased disc while restoring physiologic motion and height at the affected level. The long-term physiologic advantage of disc replacement to fusion is that preservation of motion may prevent additional degeneration at adjacent levels. METHODS: Patients meeting inclusion criteria were consented for study. Randomization was performed using a 2 to 1 ratio of disc replacement procedure to a fusion procedure. Patients rated their pain on the Visual Analogue Scale and completed the Oswestry Disability Index questionnaire. Radiographs were taken. Assessments were made before surgery and after surgery at 6 weeks, 3 months, 6 months, and 1 year (ongoing). Changes from preoperative pain, disability, or motion were separately evaluated as a function of treatment using repeated measures mixed design analysis of variance. RESULTS: This analysis includes data up to 6 months from the first 53 randomized patients. There were 35 patients who underwent disc replacements, and 18 patients had fusion procedures. Disc replacement patients had a significant reduction in pain and disability at earlier evaluations. By 6 months, the relative improvement on both the Visual Analogue Scale and Oswestry (both, P < 0.05) were similar for disc replacement and fusion patients. Greater motion was found at L4-L5 for disc replacement patients (P < 0.05) than fusion patients. A similar trend was noted at L5-S1 (P was not significant). CONCLUSIONS: Disc replacement patients reported significantly less pain (Visual Analogue Scale) and disability (Oswestry) in the early period following surgery compared to fusion patients. This difference disappeared by 6 months. When compared to fusion, the disc replacement allowed preservation of motion at L4-L5 with a similar trend at L5-S1. PMID: 14560188 [PubMed - indexed for MEDLINE]  Full Article

Although the operating microscope has been used for spine surgery for more than 20 years, its use is still not widely accepted by orthopaedic spine surgeons. Nevertheless, surgeons who have used the operating microscope are well aware of its many advantages in performing spine surgery. Most notably, the superior visualization it provides allows for faster, safer, and more extensive decompressions. The reluctance of many surgeons to use the operating microscope often has to do with trepidation regarding new technology. The use of the operating microscope when performing anterior and posterior cervical spine surgery makes these procedures easier to carry out and decreases the risk of complications during decompression of the spinal cord.  

In hopes of improving outcomes for patients with discogenic pain, less invasive techniques that reduce trauma and shorten the recovery period have been developed. This article attempts to present a comprehensive description of minimally invasive techniques, specifically heat treatments, for lumbar disc disease. The goal is to inform and educate the reader on the various thermal therapies available for lumbar disc disease by evaluating the scientific data in an objective manner. PMID: 12914265 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: A retrospective study was used to review fellowship applications over 3 years. OBJECTIVES: To assess the prevalence of research misrepresentation in orthopedic fellowship applications, and to compare such activity between subspecialties (e.g., spine, sports, hand). SUMMARY OF BACKGROUND DATA: Competition for orthopedic surgery fellowships is intense. The applicant pool includes orthopedic, plastic, and general surgeons, as well as neurosurgeons. Residency and fellowship training programs in other disciplines have documented shocking levels of misrepresentation in the curriculum vitae of prospective applicants. However, no study has looked at orthopedic residents applying for subspecialty fellowship programs. METHODS: A retrospective analysis investigated 280 applications for fellowship positions in the department of orthopedic surgery at the authors' academic institution from 1996 to 1998 inclusively. To allow for press and publication delays, a minimum 24-month follow-up period was instituted. The listings of applicants' research publications were analyzed for evidence of misrepresentation through an exhaustive literature search. Only the most obvious confirmable discrepancies were labeled as misrepresentations. The results then were compared with those found in studies conducted in other fields: gastroenterology fellowship, emergency medicine residency, pediatric residency, dermatology residency, orthopedic residency, and medical faculty applications. RESULTS: Among 280 (54%) applicants for orthopedic surgery fellowships, 151 claimed journal publications. It was found that 16 (10.6%) of these 151 applicants had misrepresented their citations. This rate was highest in spine fellowship applicants (20%). However, considering the numbers available, this was not significantly different among the various subspecialty fellowship applicants (P > 0.1). In addition, various demographic data did not correlate with the rate of misrepresentation (P > 0.1). These results are comparable with those reported in other medical fields (P > 0.1). CONCLUSIONS: Misrepresentation occurs in orthopedic fellowship applications at a rate comparable with that observed in other fields. This rate is not different among the various subspecialties in orthopedics. Policies that may lessen the incidence of falsification on curriculum vitae should be instituted in an attempt to curb such activity. PMID: 12671346 [PubMed - indexed for MEDLINE]  Full Article

Study Design. A retrospective study was used to review fellowship applications over 3 years. Objectives. To assess the prevalence of research misrepresentation in orthopedic fellowship applications, and to compare such activity between subspecialties (e.g. spine, sports, hand). Summary of Background Data. Competition for orthopedic surgery fellowships is intense. The applicant pool includes orthopedic, plastic, and general surgeons, as well as neurosurgeons. Residency and fellowship training programs in other disciplines have documented shocking levels of misrepresentation in the curriculum vitae of prospective applicants. However, no study has looked at orthopedic residents applying for subspecialty fellowship programs. Methods. A retrospective analysis investigated 280 applications for fellowship positions in the department of orthopedic surgery at the authors' academic institution from 1996 to 1998 inclusively. To allow for press and publication delays, a minimum 24-month follow-up period was instituted. The listings of applicants' research publications were analyzed for evidence of misrepresentation through an exhaustive literature search. Only the most obvious confirmable discrepancies were labeled as misrepresentations. The results then were compared with those found in studies conducted in other fields: gastroenterology fellowship, emergency medicine residency, pediatric residency, dermatology residency, orthopedic residency, and medical faculty applications. Results. Among 280 (54%) applicants for orthopedic surgery candidates, 151 claimed journal publications. It was found that 16 (10.6%) of these 151 applicants had misrepresented their citations. This rate was highest in spine fellowship applicants (20%). However, considering the numbers available, this was not significantly different among the various subspecialty fellowship applicants (P>0.1). In addition, various demographic data did not correlate with the rate of misrepresentation (P>0.1). These results are comparable with those reported in other medical fields (P>0.1). Conclusions. Misrepresentation occurs in orthopedic fellowship applications at a rate comparable with that observed in other fields. This rate is not different among the various subspecialties in orthopedics. Policies that may lessen the incidence of falsification on curriculum vitae should be instituted in an attempt to curb such activity. PMID: 15164751 [PubMed - indexed for MEDLINE]  Full Article

This study is a retrospective review of 122 patients who underwent single-level lumbar spine fusion. The objectives were to directly compare perioperative morbidity and early results of single-level anterior interbody posterolateral intertransverse process lumbar spine fusion and to provide objective findings that may be useful in selecting surgical method. Lumbar spinal fusion is a well-recognized surgical treatment of intractable low back pain resulting from DDD or spondylolisthesis. Assessments of techniques, results, and outcomes have been published, but detailed head-to-head comparisons of anterior posterior approaches with objective operative and postoperative data are not available in the literature. A retrospective review of 122 patients who underwent either an anterior interbody or posterolateral intertransverse process (average follow-up 22 and 26 months, respectively) single-level instrumented lumbar spinal fusion was performed. Surgical, perioperative, and follow-up data were obtained directly from medical records. The findings compared included estimated blood loss, need for blood transfusion, number of units transfused, operative time, number of days in hospital, need for transitional facility care, complications, need for further surgery, radiographic fusion, and clinical results. There was significantly less blood loss, need for transfusion, amount of blood transfused, operative time, and hospital stay for patients with anterior fusion procedures (p < 0.01). There was no significant difference in need for transitional facility care, complication rates, and given follow-up period in radiographic fusion rate and clinical outcome. Clinical results were significantly worse for those undergoing revision primary fusion (p < 0.01). The anterior approach to single-level lumbar fusion is associated with less morbidity than the posterolateral approach. This may in turn affect surgical outcome and hospital cost. However, both approaches to single-level lumbar fusion produce similar early fusion rates and clinical results. Revision fusions had poor early results regardless of approach. PMID: 12394658 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: Patients with low back pain were asked to recall the pain and impaired functioning that they reported 5-10 years previously as part of the National Low Back Pain prospective follow-up study. In 1998, patients completed an additional follow-up. OBJECTIVES: To compare outcomes using patient-recalled data and prospectively collected data from patients with low back pain and to identify simple, symptom-specific questions that yield reliable responses over an extended period of time. SUMMARY OF BACKGROUND DATA: Outcome assessment based on patient recall may be influenced by a patient's age, gender, reporting tendency, and current health status. The impact of data collected retrospectively on outcome analyses in spinal patients has not been addressed. METHODS: Patients enrolled in the National Low Back Pain study from 1986 to 1991 completed a self-administered questionnaire at their initial visit. A sample was interviewed by telephone in 1996 and asked to recall pain characteristics and impaired functioning reported at initial examination. A 10-year follow-up (1998) on current health status was conducted by mail. The 1998 follow-up response was separately compared with recalled and initial responses, such that two patient outcome status values were calculated for each question. Agreement was evaluated using Cohen's kappa. RESULTS: The follow-up evaluation was completed by 144 patients, with a mean interval of 9.4 years. The overall simple kappa was 0.37, indicating "fair" agreement between outcomes based on initial and recalled accounts of pain. Questions on location of pain had kappa values of 0.12-0.58, radicular symptoms 0.28-0.48, and severity of pain 0.11-0.30. CONCLUSIONS: "Fair" to "moderate" agreement was found between outcomes determined by recalled versus initial reports. Accuracy was greatest for queries on frequency, location of pain, and activities affecting pain. Discrepancies were noted for queries on severity of pain, with error bias toward less pain when using the recalled data. Careful selection of questions may yield more accurate outcome measures. PMID: 11979175 [PubMed - indexed for MEDLINE]  Full Article

A single corpectomy and strut grafting has been proposed as an alternative to performing two-level adjacent discectomies with multiple grafts to produce superior fusion rates. The purpose of this study was to compare the clinical and radiographic success of two-level discectomy and fusion with anterior cervical plate fixation compared with a single-level corpectomy. Fifty-two patients were treated with either a two-level adjacent anterior cervical discectomy and fusion with cervical plating, or by a single-level corpectomy and plate. Thirty-two patients had two-level discectomies, whereas 20 had a single corpectomy and a strut graft (average follow-up was 3.6 years). One patient had a pseudarthrosis from a single-level corpectomy and required subsequent surgery to obtain an osseous union. The fusion rates between the two groups was not statistically significant (p = 0.385). The clinical results of the surgeries were similar between the groups based on Odom's criteria. The addition of cervical plates to either two-level discectomies or single-level corpectomies yielded similar fusion and complication rates. PMID: 11389372 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: A retrospective review of all patients surgically treated by a single surgeon with a three-level anterior cervical discectomy and fusion with and without anterior plate fixation. OBJECTIVES: To compare the clinical and radiographic success of anterior three-level discectomy and fusion performed with and without anterior cervical plate fixation. SUMMARY OF BACKGROUND DATA: Previous studies of multilevel cervical discectomies and fusions have shown fusion rates to decrease as the number of surgical levels increases. Anterior cervical plate stabilization can provide more stability and may increase fusion rates for multilevel fusions. METHODS: Over a 7-year period, 59 patients were treated surgically with a three-level anterior cervical discectomy and fusion by the senior author. Forty patients had cervical plates, whereas 19 had fusions with no plates. These patients were observed for an average of 3.2 years. Clinical and radiographic follow-up data were obtained. RESULTS: Of the 59 patients, 14 had a pseudarthrosis (7 in each group). The pseudarthrosis rates were 18% (7 of 40) for patients with plating and 37% (7 of 19) for patients with no plating. Although the nonunion rate for unplated fusions was double that of plated fusions, this difference was not statistically significant. There was no statistically significant correlation between pseudarthrosis and gender, age, level of surgery, history of tobacco use, or previous anterior surgery. The fusion rates were improved with the use of a cervical plate. Inferior clinical results were demonstrated in patients with a pseudarthrosis, regardless of the use of a cervical plate. CONCLUSIONS: The addition of plate fixation for three-level anterior cervical discectomy and fusion is a safe procedure and does not result in higher complication rates. In this study, the pseudarthrosis rate was lower for patients with a cervical plate. However, this difference was not statistically significant. Patients treated with cervical plating had overall better results when compared with those of patients treated without cervical plates. Although the use of cervical plates decreased the pseudarthrosis rate, a three-level procedure is still associated with a high nonunion rate, and other strategies to increase fusion rates should be explored. PMID: 11246376 [PubMed - indexed for MEDLINE]  Full Article

STUDY DESIGN: This report describes four cases of symptomatic cerebral spinal fluid leak after lumbar microdiscectomy where ADCON-L was used. OBJECTIVES: To report that ADCON-L may exacerbate cerebral spinal fluid leak from unrecognized, small dural tears after lumbar discectomy. SUMMARY OF BACKGROUND DATA: ADCON-L is a porcine-derived polyglycan that is used with increasing frequency in spinal surgery. It is advocated to reduce postoperative peridural fibrosis and adhesions. METHODS: Four cases of symptomatic cerebral spinal fluid leak after lumbar microdiscectomy were identified. Information on these patients was obtained by chart review. RESULTS: Three patients had small, inadvertent durotomies that were not appreciated at surgery even with the aid of a microscope. The dural violation in the fourth patient occurred at the previous epidural steroid injection site located on the contralateral side of the laminotomy. CONCLUSION: ADCON-L may inhibit dural healing and exacerbate cerebral spinal fluid leak from microscopic durotomies not recognized at the time of surgery. PMID: 11148655 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: A retrospective review of all patients surgically treated with a two-level anterior cervical discectomy and fusion with and without anterior plate fixation by a single surgeon. OBJECTIVES: To compare the clinical and radiographic success of two-level discectomy and the effect of anterior cervical plate fixation. SUMMARY OF BACKGROUND DATA: Prior studies of multisegment fusions have shown decreased fusion rates correlating with the number of increased levels. The use of anterior plates for single-level cervical fusions is controversial. However, their use in multilevel fusions may be warranted because of the increased pseudarthrosis rates. METHODS: Over a 6-year period, 60 patients were treated surgically with a two-level anterior cervical discectomy and fusion by the senior author. Thirty-two patients had cervical plates, and 28 underwent fusions without plates. These patients were followed for an average of 2.7 years. Clinical and radiographic follow-up evaluations were performed. RESULTS: Of the 60 patients, 7 had a pseudarthrosis. The pseudarthrosis rates were 0% for patients with plating and 25% for those with no plating. This difference was statistically significant (P = 0.003). No correlation of pseudarthrosis with gender, age, level of surgery, history of tobacco use, or the presence of prior anterior surgery was found. There was significantly less graft collapse (P = 0.0001) in the patients without plates in whom pseudarthrosis developed (1.4 mm) than in those who had fusions with plates (0.3 mm). The amount of kyphotic deformity of the fused segment was 0.4 degree in patients with plating compared with 4.9 degrees in those without plating who developed a pseudarthrosis (P = 0.0001). CONCLUSIONS: The addition of plate fixation for two-level anterior cervical discectomy and fusion is a safe procedure with no significant increase in complication rates. The pseudarthrosis rates are significantly higher in patients treated without plate fixation. No nonunions occurred in the patients treated with plate fixation. There was significantly less disc space collapse and kyphotic deformity with the plated fusions than with the nonplated fusions, in which a pseudarthrosis developed. The complication rates for plated fusions are extremely low and do not differ from those for nonplated fusions. PMID: 10647159 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: An outcomes assessment of 14 elite college athletes who had undergone lumbar disc surgery was performed using the SF-36, a validated questionnaire that assesses quality of life. OBJECTIVES: To determine the outcomes and results of lumbar disc surgery in an elite group of athletes and compare the results with those in the general population and in age-matched control subjects. SUMMARY OF BACKGROUND DATA: Lumbar disc surgery is reported to be a highly successful procedure with excellent results. The outcome in elite athletes has not been assessed and compared with population norms and age-matched control subjects. METHODS: Fourteen athletes from schools in the National Collegiate Athletic Association with a mean age of 20.7, underwent lumbar discectomy for radiculopathy refractory to conservative treatment. Ten had a single-level microdiscectomy, three a two-level microdiscectomy, and one a percutaneous discectomy. Patients were evaluated at a mean follow-up of 3.1 years, underwent a detailed clinical evaluation, and filled out the SF-36 questionnaire. RESULTS: All 14 patients had improvement of pain with elimination of the radicular component, took less medication than before surgery, and returned to recreational sports. Nine patients, all with a single level microdiscectomy, returned to varsity sports. Five athletes prematurely retired from competitive sports because of continued symptoms. Three of the athletes who retired underwent two-level procedures, and one had a percutaneous discectomy. SF-36 scores for bodily pain, physical role, and social and mental health roles were significantly lower in those athletes who retired. Patient scores were also compared with those in a group of noninjured age-and sport-matched college athletes. There were no differences between injured and noninjured athletes, but both groups had scores significantly lower than normal values in an age-matched group for bodily pain, physical role, general health, and social function. CONCLUSIONS: All patients were satisfied with their surgeries, were greatly improved, and were pain free in activities of daily living. For a single-level microdiscectomy, the success rate in elite athletes is excellent, with 90% of athletes able to return to a high level of competition. Two-level disease may be associated with a less favorable outcome. PMID: 10101821 [PubMed - indexed for MEDLINE]   Full Article

An arthrodesis (fusion) of adjacent vertebral segments of the spinal column is surgically created in nearly 200,000 patients per year in the United States. Despite recent technical advances, the incidence of failure of such intervention is still significant. Furthermore, substantial amounts of autogenous bone graft must be procured and transplanted from the ileum to the spine to enable consolidation of a fusion mass with elements of the spinal column. The additional morbidity associated with this procedure is well known. Finally, secondary attempts at spinal fusion following initial failure have even a poorer prognosis and pose greater challenges. Advances in spinal fixation devices have addressed some mechanical considerations. However, osteogenesis and skeletal healing (fusion consolidation) are biologic processes which are facilitated but not replaced by instrumented fixation. Recently, considerable attention has been directed toward biologic considerations and, in particular, novel growth factors that regulate and promote these biologic processes. This renewed focus has been a consequence of the successful isolation, purification, and characterization of an entire family of bone morphogenetic proteins (BMPs), and the demonstration that a singular molecular species of recombinant human BMP (rhBMP) could induce the entire cascade of endochondral osteogenesis. Optimism for using such growth factors as effective bone-graft substitutes increased following a series of valuable preclinical animal experiments.  Full Article

Flexion and extension lateral radiographs of the cervical spine may suggest signs of ligamentous and soft tissue injuries in a potentially unstable spine. However, patients with acute injuries and severe pain and muscle spasms may not be able to move their necks effectively, severely compromising the diagnostic yield of the radiographs. In addition, there are reports of serious neurologic injuries occurring with the use of these radiographs in acutely injured patients. The purpose of this study was to determine the effectiveness and yield of obtaining cervical spine flexion and extension radiographs in the emergency department on acutely injured patients. Review of all patients with cervical flexion and extension radiographs presenting to a Level 1 trauma center was performed. All radiographs were judged based on the adequacy of flexion and extension movement and positive findings indicative of instability by the radiologist in the emergency room. The radiographs of one patient (0.34%) revealed positive findings of instability. Of the 290 flexion and extension radiographs, 97 (33.5%) of them showed such little or inadequate flexion or extension movement that cervical stability could not be assessed. Flexion and extension cervical radiographs should not be obtained routinely in the emergency department because 1/3 of these studies will be inadequate because of pain and muscle spasms experienced by patients. Patients with cervical injuries may not be able to fully flex and extend their necks; this may lead to false reassurance to patients who actually have had an inadequate study to diagnose potential instability. PMID: 10627694 [PubMed - indexed for MEDLINE] Full Article

The use of anterior plates for single-level cervical fusions is controversial. Previous studies that evaluated single and multiple-level fusions have shown increased and decreased fusion rates when cervical plates are used. The purpose of this study was to compare the clinical and radiographic success of single-level discectomy performed with and without anterior cervical plate fixation. During a 6-year period, 80 patients were surgically treated with a single-level anterior cervical discectomy. Forty-four patients had cervical plates, whereas 36 had fusions without plates (average follow-up, 2.3 years). The pseudarthrosis rates were 4.5% (2 of 44) for patients with plating and 8.3% (3 of 36) without plating. This difference was not significant (p = 0.653). There was no correlation of pseudarthrosis with sex, age, level of surgery, history of tobacco use, or the presence of previous anterior surgery. The amount of graft collapse for patients with plating was 0.75 mm compared with 1.5 mm for those without a plate (p = 0.026). The amount of kyphotic deformity of the fused segment was 1.2 degrees with plating compared with 1.9 degrees for patients without plating (p = 0.079). Ninety-one percent of the patients with plating had good or excellent results compared with 88% in the group without cervical plates, based on Odom's criteria. The addition of plate fixation for single-level anterior cervical discectomy and fusion is safe and not associated with a significant increase in complication rates. The pseudarthrosis rates are not significantly different when a cervical plate is used. PMID: 10598986 [PubMed - indexed for MEDLINE] Full Article

Demographic trends in the occurrence of injury and improvements in the early management of spinal trauma are changing the long-term profile of patients with spinal cord injuries. More patients are surviving the initial injury, and proportionately fewer patients are sustaining complete injuries. While preventive efforts to reduce the overall incidence of spinal cord injury are important, a number of steps can be taken to minimize secondary injury once the initial trauma has occurred. Recent efforts have focused on understanding the biochemical basis of secondary injury and developing pharmacologic agents to intervene in the progression of neurologic deterioration. The Third National Acute Spinal Cord Injury Study investigators concluded that methylprednisolone improves neurologic recovery after acute spinal cord injury and recommended that patients who receive methylprednisolone within 3 hours of injury should be maintained on the treatment regimen for 24 hours. When methylprednisolone therapy is initiated 3 to 8 hours after injury, it should continue for 48 hours. In addition to the adoption of the guidelines of that study, rapid reduction and stabilization of injuries causing spinal cord compression are critical steps in optimizing patients' long-term neurologic and functional outcomes. PMID: 10346825 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: A prospective study of tissue surrounding spinal instrumentation was performed using histologic and chemical analysis. OBJECTIVES: To identify and quantify the amount of metal debris generated by titanium pedicle screw instrumentation and to evaluate the histologic response in the spinal tissues. SUMMARY OF BACKGROUND DATA: Microscopic metal particles from the soft tissue surrounding joint arthroplasties have been shown to activate a macrophage response that leads to bone resorption and increased inflammation. The use of titanium spinal implants for spine surgery projects the possibility of generating wear debris in the spine. METHODS: Nine patients with titanium instrumentation from a prior lumbar decompression and fusion procedure who were undergoing reoperation were entered into this study. Tissue samples were collected from areas near the pedicle screw-rod junction, the scar tissue overlying the dura, and the pedicle screw holes. Metal levels for titanium were determined by electrothermal atomic absorption spectroscopy, and histologic analysis was performed by light and electron microscopy. RESULTS: Tissue concentrations of titanium were highest in patients with a pseudarthrosis (30.36 micrograms/g of dry tissue). Patients with a solid fusion had low concentrations of titanium (0.586 microgram/g of dry tissue). Standard light microscopy identified metal particles in the soft tissues. Transmission electron microscopy demonstrated macrophages with numerous secondary lysosomes containing electron-dense bodies and collagenous stroma with electron-dense rod-like profiles consistent with metal debris. CONCLUSIONS: Wear debris is generated by the use of titanium spinal instrumentation in patients with a pseudarthrosis. These particles activate a macrophage cellular response in the spinal tissues similar to that seen in surrounding joint prostheses. Patients with a solid spinal fusion have negligible levels of particulate matter. PMID: 10327512 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: An outcomes assessment of 14 elite college athletes who had undergone lumbar disc surgery was performed using the SF-36, a validated questionnaire that assesses quality of life. OBJECTIVES: To determine the outcomes and results of lumbar disc surgery in an elite group of athletes and compare the results with those in the general population and in age-matched control subjects. SUMMARY OF BACKGROUND DATA: Lumbar disc surgery is reported to be a highly successful procedure with excellent results. The outcome in elite athletes has not been assessed and compared with population norms and age-matched control subjects. METHODS: Fourteen athletes from schools in the National Collegiate Athletic Association with a mean age of 20.7, underwent lumbar discectomy for radiculopathy refractory to conservative treatment. Ten had a single-level microdiscectomy, three a two-level microdiscectomy, and one a percutaneous discectomy. Patients were evaluated at a mean follow-up of 3.1 years, underwent a detailed clinical evaluation, and filled out the SF-36 questionnaire. RESULTS: All 14 patients had improvement of pain with elimination of the radicular component, took less medication than before surgery, and returned to recreational sports. Nine patients, all with a single level microdiscectomy, returned to varsity sports. Five athletes prematurely retired from competitive sports because of continued symptoms. Three of the athletes who retired underwent two-level procedures, and one had a percutaneous discectomy. SF-36 scores for bodily pain, physical role, and social and mental health roles were significantly lower in those athletes who retired. Patient scores were also compared with those in a group of noninjured age-and sport-matched college athletes. There were no differences between injured and noninjured athletes, but both groups had scores significantly lower than normal values in an age-matched group for bodily pain, physical role, general health, and social function. CONCLUSIONS: All patients were satisfied with their surgeries, were greatly improved, and were pain free in activities of daily living. For a single-level microdiscectomy, the success rate in elite athletes is excellent, with 90% of athletes able to return to a high level of competition. Two-level disease may be associated with a less favorable outcome. PMID: 10101821 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: A review of all the presentations at three major spine specialty meetings held over a 3-year period. OBJECTIVES: To determine the rate of publication in peer-reviewed journals after presentations at major spine meetings conducted annually by the following three organizations: North American Spine Society (NASS), Scoliosis Research Society (SRS), and International Society for the Study of the Lumbar Spine (ISSLS). SUMMARY OF BACKGROUND DATA: The rate of publication for presentations at national and international meetings has been determined for medical and surgical subspecialties. This rate has been used to judge the quality of the content of the meetings and to determine the validity of the research presentations. METHODS: All presentations either in poster or oral presentation form were entered into a database covering a 3-year period for spine specialty meetings conducted annually by the following three organizations: NASS 1990 to 1992, SRS 1991 to 1993, and ISSLS 1991 to 1993. A computer search for each abstract was performed with the Melvyl Medline Plus database to determine if the abstract had been published in a peer-reviewed journal from 1990 to the end of 1997. Publication rates for presentations at these three meetings were determined over a 3-year period. RESULTS: A total of 1186 abstracts were listed over a 3-year period in the final programs of these three meetings for the years 1991 to 1993 (SRS, ISSLS) and 1990 to 1992 (NASS). Of these 1186 abstracts, 516 were published in peer-reviewed journals, giving an overall publication rate of 43.5%. The publication rates for the three different meetings (NASS, SRS, ISSLS) were similar, with values of 40%, 47%, and 45% respectively. More than 90% of the publications resulting from these meetings were published within a period of 4 years from the data of the meeting. CONCLUSIONS: The publication rates of presentations at three major spine specialty meetings are high and quite comparable with the publication rates of meetings in other medical subspecialties. This reflects the high quality of the meeting programs and validates their selection process. PMID: 10084177 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: Tantalum- and titanium-based lumbar interbody fusion devices were implanted into two fresh human cadavers, and magnetic resonance and computed tomographic imaging were performed to evaluate adjacent spinal structures and the amount of metallic artifact. OBJECTIVE: The objective of this study was to prospectively compare the preliminary results of magnetic resonance imaging and computed tomography scanning image quality after the implantation of both titanium and tantalum spinal implants. SUMMARY OF BACKGROUND DATA: The availability of tantalum and titanium spinal implants brings theoretical magnetic resonance imaging compatibility along with several other desirable characteristics. The magnetic resonance imaging and computed tomographic imaging of tantalum spinal instrumentation has never been studied previously or compared with titanium instrumentation. METHODS: Titanium and tantalum spinal implants produced for anterior spinal fusion were each placed at two levels in the lumbar spine of two fresh cadaver specimens. Sequential spin echo T1-weighted and T2-weighted magnetic resonance imaging studies and computed tomographic scans were obtained. The resulting images were then graded to describe and compare the behavior of tantalum metal in magnetic resonance imaging and computed tomographic studies. RESULTS: Good T1 and T2 images were obtained that allowed visualization of the neural structures with minimal artifact. The optimal T1 images for tantalum metal were similar in quality to the optimal T1 parameters for titanium metal. T2 images for both tantalum and titanium metal were obtained with similar results for both metals. Gradient echo magnetic resonance imaging scans of both were poorly imaged with a large amount of artifact. Computed tomographic studies of tantalum implants produced a large amount of metal artifact when compared with computed tomographic studies of titanium implants. CONCLUSIONS: High-quality magnetic resonance imaging studies can be obtained after the implantation of both titanium and tantalum spinal instrumentation. Both of the metals produce similar images on magnetic resonance imaging studies with comparable amounts of metallic artifact. High-quality computed tomographic scans of titanium implants can be obtained with minimal distortion secondary to artifact. However, computed tomographic scanning is not the imaging modality of choice for the tantalum spinal implants because of the large amounts of artifact. PMID: 9704376 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: L4-L5 intertransverse process fusions were produced with 58 micrograms, 230 micrograms, or 920 micrograms of recombinant human bone morphogenetic protein-2 in 20 dogs. Eleven had traditional decortication of posterior elements before insertion of the implant. Nine were left undecorticated. All animals were evaluated 3 months after surgery. OBJECTIVES: To determine whether decortication is a prerequisite for successful fusion in the presence of osteoinductive proteins such as bone morphogenetic protein-2. SUMMARY OF BACKGROUND DATA: Recombinant osteoinductive proteins can induce de novo bone in ectopic soft-tissue sites in the absence of bone marrow elements. Traditional methods for achieving spinal fusion rely on exposure of bone marrow through decortication to facilitate osteogenesis. It is hypothesized that the presence of an implanted osteoinductive protein obviates the need for exposure and release of host inductive factors. METHODS: Recombinant human bone morphogenetic protein-2-induced intertransverse process fusions were performed with and without decortication. Fusion sites were evaluated by computed tomography imaging, high-resolution radiography, manual testing, mechanical testing, and histologic analysis. RESULTS: One hundred percent of decorticated spines and 89% of undecorticated spines were clinically fused by 3 months. Ninety-one percent of decorticated spines and 78% of undecorticated specimens exhibited bilateral transverse process osseous bridging. The only spines that failed to achieve solid bilateral arthrodesis were in the lowest dose group. With the higher two doses, there was histologic evidence of osseous continuity between the fusion mass and undecorticated transverse processes. CONCLUSIONS: There were no statistical differences in clinical and radiographic fusion rates between decorticated and undecorticated sites. With higher doses of recombinant human bone morphoganetic protein-2, there was little histologic distinction between fusions in decorticated versus undecorticated spines. PMID: 9201852 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: Thirty-three patients with single-level, unilateral lumbosacral radiculopathy underwent micro-decompression and intraoperative dermatomal evoked potential monitoring. Side-to-side latency asymmetry was calculated. A criteria for "abnormal" was defined. Intraoperative dermatomal evoked potentials were obtained before and after decompression. The changes were correlated with clinical outcome at the 3-month follow-up examination. OBJECTIVES: To determine whether intraoperative dermatomal evoked potential latency asymmetry confirms nerve root compression and whether an improvement of latency asymmetry after decompression predicts a good clinical outcome. SUMMARY OF BACKGROUND DATA: Intraoperative dermatomal evoked potential has been proposed as a test to assess the adequacy of nerve root decompression. Initial reports suggested improvement of dermatomal evoked potential amplitude and latency after decompression. The clinical efficacy is controversial because of its technical difficulty and inherent variation. METHODS: Cervical recording was chosen to reduce the effects of anesthesia. The asymptomatic nerve root was used as a control. Quality of the tracings was determined by evoked potentials-to-noise amplitude ratio. Clinical outcome was based on patient's pain relief and satisfaction. RESULTS: Tracings of acceptable quality were obtained at baseline in 57.6% (19 of 33) of patients. A side-to-side latency asymmetry > 5% was defined as abnormal. Before decompression, 68.4% (13 of 19) of patients had an abnormal dermatomal evoked potential. After decompression, latency asymmetry returned to normal in every patient. Clinical outcome was good or excellent in 13 patients, fair in four patients, and poor in two patients. Dermatomal evoked potential latency improvements were not related to variation in clinical outcome. CONCLUSIONS: Intraoperative dermatomal evoked potential monitoring is technically demanding. Finding reproducible potentials is difficult. More research is necessary before general use of dermatomal evoked potentials for monitoring nerve root decompression. PMID: 9306525 [PubMed - indexed for MEDLINE] Full Article

This case report describes a rare but treatable complication of anterior lumbar surgery. The patient underwent a revision anterior fusion from L2 to S1. Complete thrombotic occlusion of the left iliac artery developed in the patient. Prompt recognition of vascular compromise and arterial bypass of the iliac system lead to excellent functional recovery. PMID: 9170366 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: Eleven patients with chronic renal failure and destructive spondyloarthropathy of the cervical spine were evaluated with plain radiographs, flexion-extension views, computed tomography myelogram, or magnetic resonance imaging to determine the results of surgical and nonsurgical treatment. OBJECTIVES: To determine if cervical spine fusion is an effective method of treatment for patients with chronic renal failure and destructive spondyloarthropathy. SUMMARY OF BACKGROUND DATA: Several reports have described the pathogenesis and appearance of this condition, but little has been reported about the orthopedic management of destructive spondyloarthropathy of the cervical spine. METHODS: Three patients had no spinal surgery, three patients had laminectomies alone, three patients had laminectomies with anterior fusions, and two patients had laminectomies with posterior fusions. Radiographs, computed tomography myelograms, and magnetic resonance images were evaluated to determine the results of treatment. Histologic examinations were performed in two patients. RESULTS: Patients with laminectomy alone had no improvement in pain or neurologic function (one died in the immediate postoperative period), one of three patients with anterior fusions had some improvement (one died in the immediate postoperative period), and both of those patients with posterior fusions improved, although both died within a year of surgery from unrelated causes. CONCLUSIONS: Even though the osteopenia present in patients with chronic renal failure tends to allow wire pull-out and makes internal fixation of the spine difficult, successful cervical spinal fusion can relieve pain and improve neurologic deficits in selected patients with chronic renal failure and destructive spondyloarthropathy, allowing them to remain more active for longer periods of time. PMID: 9076892 [PubMed - indexed for MEDLINE] Full Article

The presence of stainless steel implants along a spinal column causes extreme distortion of data collected by magnetic resonance (MR) imaging. The recent availability of titanium alloy spinal instrumentation systems suggests that MR imaging evaluation of the instrumented spine may now be feasible. The objective of this study was to perform MR imaging examinations on spines implanted with titanium alloy instrumentation and to determine the parameters that yield the highest quality images with the least amount of artifact. A titanium pedicle screw construct was implanted into the lumbar spine of two fresh human cadaveric specimens. Sequential spin echo MR scans were performed using various TE and TR ratios on each intact specimen. The resultant images were quantitatively graded for clarity of adjacent soft tissue and osseous structures. Excellent T1- and T2-weighted images with well-defined neural structures were obtained with minimal artifact. The optimal T1-weighted image was obtained with TE = 16 and TR = 500-600, whereas the optimal T2-weighted image was obtained with TE = 60 and TR = 1,300-1,600. By using appropriate settings, high-quality MR scans in both the T1- and T2-weighted modes can be obtained with minimal metal artifact. PMID: 9041493 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN: Nineteen dogs underwent L4-L5 intertransverse process fusions with either 58 micrograms, 115 micrograms, 230 micrograms, 460 micrograms, or 920 micrograms of recombinant human bone morphogenetic protein-2 carried by a polylactic acid polymer. A previous study (12 dogs) compared 2300 micrograms of recombinant human bone morphogenetic protein-2, autogenous iliac bone, and carrier alone in this model. All fusions subsequently were compared. OBJECTIVES: To characterize the dose-response relationship of recombinant human bone morphogenetic protein-2 in a spinal fusion model. SUMMARY OF BACKGROUND DATA: Recombinant osteoinductive morphogens, such as recombinant human bone morphogenetic protein-2, are effective in vertebrate diaphyseal defect and spinal fusion models. It is hypothesized that the quality of spinal fusion produced with recombinant human bone morphogenetic protein-2, above a threshold dose, does not change with increasing amounts of inductive protein. METHODS: After decortication of the posterior elements, the designated implants were placed along the intertransverse process space bilaterally. The fusion sites were evaluated after 3 months by computed tomography imaging, high-resolution radiography, manual testing, mechanical testing, and histologic analysis. RESULTS: As in the study using 2300 micrograms of recombinant human bone morphogenetic protein-2, implantation of 58-920 micrograms of recombinant human bone morphogenetic protein-2 successfully resulted in intertransverse process fusion in the dog by 3 months. This had not occurred in animals containing autograft or carrier alone. The cross-sectional area of the fusion mass and mechanical stiffness of the L4-L5 intersegment were not dose-dependent. Histologic findings varied but were not related to rhBMP-2 dose. Inflammatory reaction to the composite implant was proportional inversely to the volume of the fusion mass. CONCLUSIONS: No mechanical, radiographic, or histologic differences in the quality of intertransverse process fusion resulted from a 40-fold variation in dose of recombinant human bone morphogenetic protein-2. PMID: 8893436 [PubMed - indexed for MEDLINE] Full Article

Fresh frozen human cadaveric spinal specimens (T8-S1) were subjected to pure flexion extension bending moment and pure axial torque loadings while intervertebral rotations were recorded at the L3-L4, L2-L3, and Ll-L2 discs. A standardized unstable defect was created at the L3-L4 disc, and loading tests were repeated after application of bilateral Steffee plates in 2 configurations: a short plate with 2 pedicle screws (spanning the defect) and a longer plate with 3 pedicle screws (spanning the defect and 1 disc above). Each plating configuration was tested in the unlocked state (nuts compressing the plate down onto the spine) and locked state (nuts above and below the plate tightened against each other to clamp the plate to the screws). Locking the plates to the screws had no effect on any intervertebral rotation at any disc level. Use of a longer plate that also spanned the disc above the defect offered no advantage in controlling flexion extension rotations at the defect site. However, mean torsional rotation at the defect site with the 3-screw plate was approximately 50% of the mean for a 2-screw plate. Extension and torsional rotations at the L2-L3 disc (1 level above the defect site) were unaffected by application of a 2-screw plate; flexion rotation at this level increased slightly after plating. All motions at the L2-L3 disc were reduced (as would be expected) when the 3-screw plate spanned this uninjured disc. Plating the defect had no effect on disc rotations at the L1-L2 disc (2 levels above the fracture site). PMID: 8641075 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN. Twenty sheep underwent anterior lumbar interbody fusions with either a threaded titanium interbody fusion device (cage, n = 8), autogenous iliac crest dowel graft (autograft, n = 6), or interbody decortication only (sham, n = 6). Two sheep had misplaced cages and were excluded. Sheep were killed after 6 months. OBJECTIVES. To determine whether this model is useful for examining the distractive and fixation properties of interbody fusion cages. SUMMARY OF BACKGROUND DATA. Interbody fusion cages are used in anterior lumbar interbody fusion procedures to provide immediate intersegmental fixation and to distract and preserve interbody height. The process of physiologic anchorage by bone ingrowth into such devices is under investigation. METHODS. Sheep were radiographed immediately after surgery and 2, 4, and 6 months after surgery. Interbody distraction and angulation were measured with a digital photo image analyzer at each time point. After the sheep were killed, stiffness to flexion, extension, and lateral bending moments were measured. Twelve untreated cadaver spines were also tested for comparison. RESULTS. After surgery, interbody distraction successfully occurred in cage and autograft-implanted sites. Loss of interbody height ensued, however, in all groups during the first 2 months. Percentage loss of height was lowest in cage sites. By 6 months, only cage sites remained distracted beyond normal. Fusions in all groups were stiffer than untreated spines. Autograft sites were stiffer than cage sites to lateral bending. Sham sites were stiffer than cage and autograft sites to flexion, but this likely resulted from complete intervertebral collapse. CONCLUSION. Despite early subsidence, interbody fusion cages successfully distracted and preserved interbody spaces. This model is useful for investigating methods of improving distraction and stabilization. PMID: 8727195 [PubMed - indexed for MEDLINE] Full Article

The presentation and clinical course for hematogenous vertebral osteomyelitis and postoperative discitis is presented. The treatment is primarily conservative care in the form of immobilization and parenteral antibiotics. The indications for surgery are rare and should be reserved for patients resistant to treatment or with septic course, abscess formation, or neurologic deficits. In these cases, the infectious process has generally involved the adjacent vertebrae or the neural elements. Surgery usually involves an anterior approach. The principles of surgical treatment involve debridement of necrotic tissue, decompression of neural elements, and stabilization of the spine. The outcome of patients with vertebral osteomyelitis and secondary discitis in general is favorable when appropriate treatment is rendered. Extension of the infection to the spinal canal in the form of an epidural abscess is also reviewed. PMID: 8539056 [PubMed - indexed for MEDLINE] Full Article

We evaluated magnetic resonance imaging studies of thirty patients before and after a contained herniation of a lumbar disc was treated with a percutaneous lumbar discectomy. The imaging studies were evaluated to determine whether the preoperative appearance of the herniated disc was predictive of the outcome of percutaneous discectomy and also to determine a possible mechanism of action of the procedure in the relief of symptoms. The index operation was successful in seventeen (57 per cent) of the thirty patients. The preoperative imaging studies showed no differences in the appearance of the discs that went on to have a successful result and those that went on to have an unsuccessful result. Imaging studies made four to six weeks after the operation showed no measurable changes in the morphology of the disc. Imaging studies made a mean of fourteen months after the operation showed no changes in the morphology of the disc in twenty-four (80 per cent) of the patients, irrespective of the clinical outcome. Only three of the seventeen patients who had a successful result had a reduction of more than two millimeters in the size of the herniated segment, and two of the thirteen patients who had an unsuccessful result had an increase of more than one millimeter in the size of the herniated segment. We found that preoperative imaging studies cannot predict the clinical outcome of percutaneous lumbar discectomy.(ABSTRACT TRUNCATED AT 250 WORDS) PMID: 7713975 [PubMed - indexed for MEDLINE] Full Article

METHODS. Eleven patients with paralysis, secondary to rheumatoid arthritis of the cervical spine were analyzed postmortem. Neurologic classification (Ranawat) included one Class 2, four Class IIIA, and six Class IIIB. Rheumatologic changes included atlantoaxial subluxation, basilar invagination, and subaxial subluxation. During autopsy the entire cervical spine was removed, including the occiput and foramen magnum. The spinal cord and medulla oblongata were removed en toto and examined histologically by a neuropathologist. RESULTS. Nine of the eleven cases revealed abnormal histology of the spinal cord, and in two patients, the spinal cords were normal. Three histologic types of spinal cord compression were identified. In Type 1 (four cases) severe chronic mechanical compression revealed marked mechanical distortion, flattening, and destruction of the cord with secondary Wallerian degeneration of the ascending and descending tracts without anoxicischemic neuron changes. In Type 2 (three cases), there was vascular compression showing ischemic damage to the cord with necrosis of the lateral columns in the ischemic watershed regions supplied by anterior and posterior spinal arteries. In Type 3 (two cases), there was mild mechanical compression showing focal gliosis at the site of compression without ascending or descending tract injury. Two of the eleven cases had thrombosis of the vertebral arteries. Of the eleven cases analyzed, two had normal spinal cords. CONCLUSION. This autopsy analysis of rheumatoid cervical spine suggests that paralysis can be due to both mechanical neural compression and/or vascular impairment. PMID: 7846570 [PubMed - indexed for MEDLINE] Full Article

STUDY DESIGN. Patients undergoing spinal surgery were monitored for sodium balance, fluid type, and volume input and output during surgery and for the first 3 postoperative days. OBJECTIVE. To prospectively document the true incidence of the syndrome of inappropriate antidiuretic hormone secretion and hyponatremia, and identify risk and protective factors for the development of the syndrome of inappropriate antidiuretic hormone secretion after spinal surgery. METHODS. Data on medical history, surgical procedure, estimated blood loss, and volumes and types of intraoperative and postoperative fluids were collected on 116 consecutive spinal surgery patients during March to July 1992. RESULTS. One hundred one spinal operations in 96 patients were evaluated. There were 48 males and 48 females, with a mean age of 52 years (range, 16 to 90 years). Hyponatremia developed in 45 (44.6%) patients. The etiology of hyponatremia was the syndrome of inappropriate antidiuretic hormone secretion in seven patients (6.9%), hypovolemia in 19 patients (18%), and other causes in six patients. CONCLUSIONS. Spine patients are at risk for hyponatremia and the syndrome of inappropriate antidiuretic hormone secretion. The incidence of the syndrome of inappropriate antidiuretic hormone secretion was 6.9%. Serum sodium should be monitored postoperatively. Patients who undergo a revision operation have an approximately two to four times greater risk of being affected by the syndrome of inappropriate antidiuretic hormone secretion than those who have primary surgery. PMID: 7973959 [PubMed - indexed for MEDLINE] Full Article

Anterior decompression of the thoracic and lumbar spine is indicated for patients with trauma, infection, or tumor that causes compression of the neural tissues, resulting in an incomplete neurologic deficit. The complication of chronic pain, with or without paralysis, that results from fractures with canal compromise has received little attention. This study involved 45 patients who had anterior decompression for chronic pain or paralysis at an average of 4.5 years after having thoracolumbar fractures. Pain was improved in 41 of 45 patients, with complete relief in 30 and partial relief in 11. In 25 patients with neurologic deficit, 21 noted improvement, 14 of which improved one or more grades of the Eismont classification. No patient had an increase in pain or loss of neurologic function. Complications were few. Anterior decompression of the thoracolumbar spine for chronic pain after thoracolumbar fractures is a safe and effective treatment for patients with this uncommon and difficult problem. PMID: 8131342 [PubMed - indexed for MEDLINE] Full Article

In an attempt to determine the expected long-term appearance of the lumbar spine in patients who have undergone successful lumbar discectomy, follow-up magnetic resonance (MR) examinations were performed on 23 patients (26 levels). All patients in the study had undergone at surgery at least one year prior to the study. All patients met rigorous criteria for a successful outcome. In nine cases, the postoperative study indicated a virtually total resolution of the previously identified disc herniations. In 13 cases, the study noted moderate, persistent posterior contour defects in the disc that contributed to persistent mass effect on the thecal sac or corresponding nerve root. In the remaining four cases, the postoperative study indicated virtually no change in the apparent contour of the posterior disc margin. Gadolinium contrast examinations demonstrated enhancement of the persistent contour abnormalities in 18 of 19 disc levels, suggesting the common presence of fibrosis, which was at times "mass-like," in these successful patients. These findings suggest that localized discal contour abnormalities morphologically simulating recurrent disc herniations and variably contributing to mass effect, may be commonly encountered in long-term follow-up imaging studies of successful discectomy patients. PMID: 8367773 [PubMed - indexed for MEDLINE] Full Article

A 62-year-old man demonstrated symptoms, signs, and radiographic evidence of lumbar spinal stenosis and intraoperative pathologic findings of tophaceous deposition in the ligamentum flavum. Although there have been reports of cervical calcium pyrophosphate dihydrate crystal deposition (CPPD) with neurologic compression, this report appears to be the first case of lumbar spinal stenosis secondary to CPPD. Cervical calcium pyrophosphate dihydrate crystal deposition should be added to the differential diagnosis of spinal stenosis. PMID: 8472402 [PubMed - indexed for MEDLINE] Full Article

In this study, truncal deformity in patients with scoliosis was evaluated by circumferential scanning using an optoelectronic device (Optronic Torsograph, Anima Corp., Tokyo, Japan). This device generates cross-sectional skin surface topography at 10 axial levels to provide a three-dimensional representation of truncal shape. Ninety-three patients with suspected idiopathic scoliosis were evaluated with conventional Cobb measurements, and their parameters were computed using the device's measurements. The geometric cross-sectional indexes correlated poorly with the Cobb angle and were highly variable during repeated measurements. The optoelectronic device's angle, a measure of centroid curvature, correlated highly with the Cobb angle for primary spinal curves. The highest correlation was observed in thoracolumbar curves. This optoelectronic device has clinical relevance as a method for further scoliosis screening and monitoring the progression of spinal curvature in a patient. PMID: 8475431 [PubMed - indexed for MEDLINE]  Full Article

An identifiable lumbar nerve root compression appears to cause urological dysfunction consistent with interstitial cystitis. Ten patients (9 females, 1 male) were evaluated for chronic pelvic pain. Cystoscopic and histological appearances were consistent with a diagnosis of interstitial cystitis. Magnetic resonance studies of the lower spine consistently demonstrated a lateral compression of the L5 dorsal nerve root. Decompression of the lateral foramina of L5 resulted in immediate relief of pain in 9 patients, who have been followed up for 6 months without a recurrence. Possible mechanisms involving sympathetic dystrophy of the pelvic plexus are reviewed. PMID: 1933154 [PubMed - indexed for MEDLINE] Full Article

An animal model of cauda equina syndrome was developed. Neurologic recovery was analyzed following immediate, early, and delayed decompression. Five experimental groups, each containing six dogs, were studied. Compression of the cauda equina was performed in all 30 dogs following an L6-7 laminectomy. The cauda equina was constricted by 75% in each group. The first group was constricted and immediately decompressed. The remaining groups were constricted for 1 hour, 6 hours, 24 hours, and 1 week, respectively, before being decompressed. Somatosensory evoked potentials were performed before and after surgery, before and immediately after decompression, and 6 weeks following decompression. Daily neurologic exams using the Tarlov grading scale were performed. At 6 weeks postdecompression, all dogs were killed, and the neural elements analyzed histologically. Following compression, all 30 dogs had significant lower extremity weakness, tail paralysis, and urinary incontinence. All dogs recovered significant motor function 6 weeks following decompression. The dogs with immediate decompression generally recovered neurologic function within 2-5 days. The dogs receiving 1-hour and 6-hour compression recovered within 5-7 days. The dogs receiving 24-hour compression remained paraparetic 5-7 days, with bladder dysfunction for 7-10 days and tail dysfunction persisting for 4 weeks. The dogs with compression for 1 week were paraparetic (Tarlov Grade 2 or 3) and incontinent during the duration of cauda equina compression. They recovered to walking by 1 week and Tarlov Grade 5 with bladder and tail control at the time of euthanasia. Immediately after compression, all five groups demonstrated at least 50% deterioration of the posterior tibial nerve evoked potential amplitudes. (ABSTRACT TRUNCATED AT 250 WORDS) PMID: 1948393 [PubMed - indexed for MEDLINE] Full Article

This may be the first documented case in the United States and in the orthopedic literature of transfusion-transmitted human T-cell leukemia virus Type I (HTLV-I)-associated myelopathy (HAM). Progressive myelopathy occurred in a 58-year-old white man with serologic and molecular evidence of HTLV-I infection after multiple trauma and subsequent transfusion with multiple units of banked blood products. Symptoms of myelopathy occurred 15 months after the transfusions. Myelopathy from HTLV-I infection simulates a disorder of orthopedic interest. Physicians should be aware of the symptoms of HAM and unexplained myelopathy. PMID: 2225623 [PubMed - indexed for MEDLINE] Full Article

Twenty female beagle dogs underwent an L6-7 laminectomy and six dogs each had 25, 50 or 75% constriction of the cauda equina and 2 control dogs had laminectomy only. Cystometrograms were performed pre- and post-operatively and three months after constriction. Cortical evoked potentials were monitored pre- and post-operatively and monthly for three months. After three months of constriction, the cauda equina of these dogs in each group was examined histologically and vascular circulation was examined by latex and India ink injection (Spalteholz technique). The control dogs had normal CMGs and CEPs. Twenty-five percent constriction caused no CMG changes and mild CEP changes. Fifty percent constriction caused no statistically significant CMG changes, major CEP changes and venous congestion of the nerve roots and dorsal root ganglia. Seventy-five percent constriction produced severe CMG changes with detrusor areflexia, increased bladder capacity and clinical incontinence. CEPs also had marked deterioration. Vascular analysis revealed severe arterial narrowing at the level of constriction and venous congestion of the nerve roots and dorsal root ganglia. Blockage of axoplasmic flow and nerve root atrophy was seen in all dogs with 75% constriction. Cortical evoked potentials were the most sensitive predictor of neural compression. CMGs were not sensitive until severe compression was achieved. Bladder dysfunction, i.e., detrusor areflexia, appears to occur with blockage of axoplasmic flow and early sensory changes occur with neurovenous congestion. PMID: 2259971 [PubMed - indexed for MEDLINE] Full Article

Primary osseous neoplasms of the thoracic and lumbar spine are uncommon lesions. Between 1965 and 1982, of 1971 patients with musculoskeletal neoplasms, only 29 (1.5%) had primary osseous tumors in these locations. There were eight children and 21 adults. Back pain was the most common complaint in 25 patients (86%), and neurologic symptoms or deficits were present in 16 patients (55%). All lesions were visible on routine spine roentgenograms, while computed tomography and myelography demonstrated spinal canal encroachment and extradural spinal cord compression in 19 patients (66%). The histologic diagnoses included 11 benign and 18 malignant lesions. Benign lesions occurred predominantly in children and malignant tumors in adults. Treatment was individualized, based on the histologic diagnoses. Twenty-two patients had surgical resection of their lesions. Laminectomy without stabilization and arthrodesis resulted in late instability and neurologic deterioration in three of seven patients (43%) with malignant lesions. Resection and decompression combined with arthrodesis did not predispose to late instability. Twenty-one patients were followed for a mean of 4.1 years (range, two to 14 years). Eight patients died from malignant disease between one month and seven years after diagnosis. PMID: 2142033 [PubMed - indexed for MEDLINE] Full Article

Twenty-four cases of lumbar arachnoiditis were evaluated by magnetic resonance (MR) imaging. The morphologic changes of arachnoiditis by MR were compared in 20 cases with CT myelography (CTM) and plain film myelography (PFM). An abnormal configuration of nerve roots was seen by MR. Three anatomic groups were identified. Group 1 showed conglomerations of adherent nerve roots residing centrally within the thecal sac. Group 2 demonstrated nerve roots adherent peripherally to the meninges, giving rise to an "empty sac" appearance. Group 3 showed a soft tissue mass replacing the subarachnoid space. Magnetic resonance imaging resulted in accurate diagnosis, and had excellent correlation with CT myelography and plain film myelographic findings in the diagnosis of lumbar arachnoiditis. PMID: 2353276 [PubMed - indexed for MEDLINE] Full Article

An animal model of lumbar spinal stenosis was developed in which the pathophysiology of this condition could be examined. Four experimental groups, each containing six dogs, were studied. One group had a laminectomy of the sixth and seventh lumbar vertebrae only; these animals served as controls. In the three other groups, a laminectomy was performed and the cauda equina was constricted by 25, 50, or 75 per cent to produce chronic compression. Cortical evoked potentials were recorded preoperatively, immediately after constriction, and at one, two, and three months postoperatively. Daily neurological examinations were carried out, and the neurological deficits were graded using the Tarlov system. After three months of constriction, the cauda equina of three dogs in each group was examined histologically, and the vascular circulation was examined by latex and India-ink injection with a modification of the Spalteholz technique. The animals in the control group showed no neurological abnormalities, no changes in cortical evoked potentials, normal microvascularity, and no histopathological changes in the nerve roots or the spinal cord. The dogs in which the cauda equina had been constricted 25 per cent had no neurological deficits, mild changes in cortical evoked potentials, slight histological changes, and venous congestion of the root and dorsal root ganglion of the seventh lumbar nerve. The dogs in which the cauda equina had been constricted 50 per cent had mild initial motor weakness, major changes in cortical evoked potentials, edema and loss of myelin in the root of the seventh lumbar nerve, and moderate or severe venous congestion of the root and dorsal root ganglion of the seventh lumbar nerve. The dogs in which the cauda equina had been constricted 75 per cent had significant weakness, paralysis of the tail, and urinary incontinence; two dogs recovered by the third month, but all had neurogenic claudication for three months. All six dogs had dramatic changes in cortical evoked potentials and had complete nerve-root atrophy at the level of the constriction. There was blockage of axoplasmic flow and wallerian degeneration of the motor nerve roots distal to the constriction and of the sensory roots proximal to the constriction, as well as degeneration of the posterior column. Severe arterial narrowing at the level of the constriction and venous congestion of the roots and dorsal root ganglia of the seventh lumbar and first sacral nerves were also present. Cortical evoked potentials revealed neurological abnormalities before the appearance of neurological signs and symptoms.(ABSTRACT TRUNCATED AT 400 WORDS) PMID: 2295658 [PubMed - indexed for MEDLINE] Full Article

Relative degrees (25%, 50% or 75%) of constriction of the entire cauda equina at the seventh lumbar level were performed on eighteen pure bred female beagle hounds by surgically implanting a circular polyethylene loop with an imbedded stainless steel wire. The wire was mechanically constricted by external control and the degree of compression was confirmed by pre- and postoperative magnetic resonance imaging or computed tomography scanning. A control group of two dogs had laminectomy only. Neurologic function was evaluated daily. Cystometrics were performed on each dog after constriction had been present for three months. Cortical evoked potentials (CEPs) were obtained on all dogs preoperatively, immediately following constriction and at monthly intervals for three months. Dogs were sacrificed at three months and the cauda equina and spinal cord were examined histopathologically. Cystometric tracings were noted to become a flat line with 75% compression of the cord. Less compression had minimal effect on the cystometric curves. The mean latency, determined by cortical evoked potentials, was noted to increase by 3.2%, 7.8%, and 17.2% immediately after 25%, 50% and 75% constriction, respectively. Histologic changes ranged from occasional enlargement of the axons on the periphery of the cauda equina with 25% constriction to severe loss of all axons and atrophic roots at the level of the constricting band with 75% constriction. PMID: 2294251 [PubMed - indexed for MEDLINE] Full Article

Thirty-nine patients with tibial plateau fractures and concomitant ligament injury were evaluated at least one year after injury. Ligamentous injury was determined by stress roentgenograms, plain roentgenograms, operative findings, and Pelle-grini-Stieda's ossification. There were 22 isolated medial collateral, eight lateral collateral, one isolated anterior cruciate, and eight combined ligament injuries. All types of tibial plateau fractures were associated with ligamentous injury, although split compression and local compression were most common. Twenty patients (Group 1) did not have operative repair of the injured ligaments, and 19 patients (Group 2) had primary repair of the injured ligaments. Open reduction and internal fixation of the plateau fracture(s) were performed in 13 patients in Group 1 and 19 patients in Group 2. Follow-up evaluation (100-point scale), including subjective, functional, and anatomic factors, revealed 12 excellent and good, four fair, and three poor results in the 19 patients with ligamentous repair. There were ten excellent and good, two fair, and eight poor results in those without ligament repair. Ten of the 12 patients with 10 degrees or more of instability had poor results. These poor results included five unrepaired medial collateral ligaments, two unrepaired lateral collateral ligaments, and three patients with cruciate ligament injury. This study confirms the view that instability is a major cause of unacceptable results in tibial plateau fractures. Operative repair of medial and lateral collateral ligaments, with appropriate treatment of the bony plateau fracture, may reduce late instability and may improve overall morbidity in these concomitant injuries. Cruciate ligament injury associated with a tibial plateau fracture carries a poor prognosis. PMID: 2293934 [PubMed - indexed for MEDLINE] Full Article

From our patients who had idiopathic scoliosis, we identified a subset of eighteen in whom Harrington rods were used for fixation down to the fifth lumbar vertebra. In five of these patients, low-back pain, sciatica, and other neurological problems developed at two to thirty-two months after arthrodesis. These complications were caused by migration of the caudad hook into the spinal canal. The migration was probably caused by a combination of lumbosacral lordosis and mobility of the fifth lumbar vertebra (the most caudad mobile segment) on the segment below, resulting in weakening of the lamina of the fifth lumbar vertebra. After removal of the hardware, all patients had improvement of the lumbosacral and radicular pain as well as resolution of the neurological abnormalities. PMID: 2668293 [PubMed - indexed for MEDLINE] Full Article

A white man with a progressive spastic paraparesis that began 15 months after sustaining severe trauma in a motor vehicle accident was positive for antibodies to human T-lymphotropic virus type I (HTLV-I) by enzyme-linked immunosorbent assay. Serum antibody to HTLV-I was confirmed by Western blot and radioimmunoprecipitation assay. We detected specific proviral DNA in peripheral blood lymphocytes by the polymerase chain reaction. Because the incidence of HTLV-I is generally restricted to Southern Japan and Caribbean black populations, the most likely source of HTLV-I infection in this patient was multiple intraoperative blood transfusions. The relatively short interval between transfusion and development of HTLV-I-associated myelopathy is consistent with the more rapid evolution of this clinical syndrome compared with adult T-cell leukemia. PMID: 2725879 [PubMed - indexed for MEDLINE] Full Article

Three hundred six tibial plateau fractures treated at the authors' institutions and in private practice were analyzed in relation to the use of a cast brace or fracture brace. One hundred forty-one of these patients had had a cast brace or fracture brace as part of their treatment program, either as the primary fracture treatment or after open reduction or traction. The aims of this study were (1) to determine if cast bracing could maintain alignment, fracture position, and range of motion and (2) to compare its results with those of other major long-term studies of similar fractures. There were 85 lateral, 24 medial, and 32 bicondylar fractures. Cast bracing was used for one to 17 weeks, with a mean of eight weeks. Ninety-nine of the 141 patients were followed for at least one year. Eighty-two of the patients maintained alignment with less than 5 degrees of deformity, and fracture position was maintained in 85% of cases, with only 15% having 4-8 mm of loss of position. Medial plateau and subcondylar fractures had an increased incidence of fracture position loss. Ninety-seven percent of patients had greater than 90 degrees of flexion, and 90% had full extension, i.e., less than 5 degrees of contracture. Pain was minimal or absent after heavy exercise in 90% of patients using cast bracing. Arthritic changes on roentgenographic analysis were absent or mild in 93.5% and moderate or severe in 6.5% of patients. Complications, including phlebitis, pulmonary emboli, wound infection, hardware slippage, and skin slough, occurred in nine patients.(ABSTRACT TRUNCATED AT 250 WORDS) PMID: 2706855 [PubMed - indexed for MEDLINE] Full Article

To define the time course and mechanism of enhancement of epidural fibrosis after gadolinium-DTPA (Gd-DTPA) injection, we undertook a three-part study in humans and dogs with epidural scar after spine surgery. First, the dynamic in vivo contrast-enhancing properties of epidural scar were assessed by using sequential fast (18-sec) spin-echo sequences after contrast injection. Epidural scar in dogs rapidly enhanced; peak enhancement (101%) was 6 min after injection, with a slower decline toward baseline to 45% after 44 min. Epidural fibrosis in patients followed a similar pattern, with a maximum enhancement of 73% after 5 min. Paraspinal muscle had a lower peak enhancement in both patients (36%) and dogs (22%). Second, vascular injection in two dogs with India ink demonstrated multiple small vessels throughout the epidural scar. Third, light and electron microscopy was performed on epidural scar obtained at reoperation in both patients and dogs. Light microscopy showed multiple small capillaries scattered throughout a background of collagen. Electron microscopy demonstrated a wide variation in the junctions between endothelial cells ranging from "tight" to "loose." Regions of endothelial discontinuity were also visualized. This study suggests that Gd-DTPA diffuses rapidly into the extravascular space in epidural scar, with a slower, net movement toward the intravascular compartment as the agent is renally filtered. The contrast agent transgresses the endothelium through "leaky" intercellular junctions and areas of endothelial discontinuity. PMID: 2784266 [PubMed - indexed for MEDLINE] Full Article

Thirty patients with failed back surgery syndrome were studied to evaluate the effectiveness of magnetic resonance (MR) imaging with gadolinium-diethylenetriaminepentaacetic acid/dimeglumine (Gd-DTPA) in differentiating postoperative epidural fibrosis (scar) from recurrent disk herniation. Pre- and postcontrast MR images were interpreted without access to other diagnostic, surgical, or pathologic findings. Seventeen patients had surgical and pathologic correlation of the MR findings at 19 disk levels. The precontrast studies had a sensitivity, specificity, and accuracy of 100%, 71%, and 89%, respectively. The enhanced MR studies correctly depicted the character of abnormal epidural soft tissue in 17 patients at all 19 levels. Scar showed heterogeneous enhancement on the early T1-weighted spin-echo images obtained within 10 minutes after contrast material administration. Herniated disk did not show significant enhancement on the early studies but showed variable degrees of enhancement on delayed images in nine of 12 cases. Other criteria were found to be less useful than the pattern of enhancement. Results indicate that precontrast and early postcontrast T1-weighted spin-echo studies are highly accurate in separating epidural fibrosis from herniated disk. PMID: 2966418 [PubMed - indexed for MEDLINE] Full Article

Between 1973 and 1983, 27 patients with acute femoral neck fractures were treated at the UCLA Medical Center with total hip arthroplasty. These cases were selected on the basis of age, high activity level, and degenerative changes in the acetabular cartilage. The average age was 72 years. There were 19 women and eight men. The average follow-up period was 3.8 years with a range of one to ten years. Methods used included analysis of clinical data, roentgenograms, final pain ratings, walking ratings, and activity levels using the UCLA rating system. Pain relief and overall functional results were better than that of most series of acute femoral neck fractures treated with hemiarthroplasty and similar to that of total hip arthroplasty series. The complication rate was slightly less than both authors' elective total hip series, and considerably less than most hemiarthroplasty series. Complications included a superficial wound infection, a urinary tract infection, and a perforated colon diverticulum. Four patients died within one year from causes unrelated to the hip arthroplasty. There were no deep infections, dislocations, or reoperations. Total hip arthroplasty in selective cases of acute femoral neck fractures can give more consistent pain relief and better functional results than hemiarthroplasty, without an increase in complications. PMID: 3568498 [PubMed - indexed for MEDLINE] Full Article