John G. Heller

Increased swelling complications associated with off-label usage of rhBMP-2 in the anterior cervical spine

Study Design/Setting. Independent, retrospective clinical record review with a concurrent control. Objective. To identify whether rhBMP-2 is associated with an increased incidence of clinically relevant postoperative prevertebral swelling problems in patients undergoing anterior cervical fusions. Summary of Background Data. Bone Morphogenetic Protein-2 (rhBMP-2) is FDA approved as a bone graft substitute in anterior lumbar interbody fusions. rhBMP-2 has also been used “off-label” in anterior cervical fusions. We suspected that rhBMP-2 might increase the incidence of adverse swelling events. Methods. A total of 234 consecutive patients (ages 12–82 years) undergoing anterior cervical fusion with and without rhBMP-2 over a 2-year period at one institution comprised the study population. The incidence of clinically relevant prevertebral swelling was calculated. The populations were compared and statistical significance was determined. Results. A total of 234 patients met the study criteria, 69 of whom underwent anterior cervical spine fusions using rhBMP-2; 27.5% of those patients in the rhBMP-2 group had a clinically significant swelling event versus only 3.6% of patients in the non-rhBMP-2 group. This difference was statistically significant (P < 0.0001) and remained so after controlling for other significant predictors of swelling. Conclusions. Off-label use of rhBMP-2 in the anterior cervical spine is associated with an increased rate of clinically relevant swelling events.

Comparison of BRYAN Cervical Disc Arthroplasty With Anterior Cervical Decompression and Fusion : Clinical and Radiographic Results of a Randomized, Controlled, Clinical Trial

Study Design. A prospective, randomized, multicenter study of surgical treatment of cervical disc disease. Objective. To assess the safety and efficacy of cervical disc arthroplasty using a new arthroplasty device at 24-months follow-up. Summary of Background Data. Cervical disc arthroplasty preserves motion in the cervical spine. It is an alternative to fusion after neurologic decompression, whereas anterior decompression and fusion provides a rigorous comparative benchmark of success. Methods. We conducted a randomized controlled multicenter clinical trial enrolling patients with cervical disc disease. Ultimately 242 received the investigational device (Bryan Cervical Disc), and 221 patients underwent a single-level anterior cervical discectomy and decompression and fusion as a control group. Patients completed clinical and radiographic follow-up examinations at regular intervals for 2 years after surgery. Results. Analysis of 12- and 24-month postoperative data showed improvement in all clinical outcome measures for both groups; however, 24 months after surgery, the investigational group patients treated with the artificial disc had a statistically greater improvement in the primary outcome variables: Neck disability index score (P = 0.025) and overall success (P = 0.010). With regard to implant- or implant/surgical-procedure-associated serious adverse events, the investigational group had a rate of 1.7% and the control group, 3.2%. There was no statistical difference between the 2 groups with regard to the rate of secondary surgical procedures performed subsequentto the index procedure. Patients who received the artificial cervical disc returned to work nearly 2 weeks earlier than the fusion patients (P = 0.015). Conclusion. Two-year follow-up results indicate that cervical disc arthroplasty is a viable alternative to anterior cervical discectomy and fusion in patients with persistently symptomatic, single-level cervical disc disease.

Complications of Posterior Cervical Plating

Study Design This retrospective clinical study evaluates complications occurring during or immediately after surgery of posterior cervical plating. Objectives The present study quantities risks associated with posterior cervical plating using lateral mass screw fixation. The observed clinical complications are compared with theoretical risks previously studied in cadavers. Unanticipated complications are identified. Summary of Background Data There are many reports that describe posterior cervical plating and attempt to describe the indications for using this type of fixation, but few studies have discussed the clinical complications incurred by application of these plates and screws. Methods Seventy-eight consecutive patients whose treatment included posterior cervical lateral mass plating were independently reviewed to identify associated complications. The average patient age was 52.9 years, and the average follow-up period was 2 years (range, 10–47 months). Multiple indications for surgery were present, but complex reconstructive procedures were required in 70.5% of cases. Complication rates were calculated as either a percentage of the number of screws inserted or as a percentage of the number of cases performed or both. Results Six hundred fifty-four screws were inserted—an average of 8.4 screws per patient. Complication rates as a function of the number of screws inserted included nerve root injury, 0.6%; facet violations, 0.2%; vertebral artery injury, 0%; broken screw, 0.3%; screw avulsion, 0.2%; and screw loosening 1.1% Complications as a percentage of the number of cases performed included spinal cord injury, 2.6%; iatrogenic foraminal stenosis, 2.6%; broken plate, 1.3%; lost reduction, 2.6%; adjacent segment degeneration, 3.8%; infection, 1.3%; and pseudoarthrosis, 1.4%. Conclusions Cadaveric work has predicted certain anatomic complications rates associated with lateral mass screw insertion. This study finds the risk of lateral mass screw insertion to be considerably less than predicted in vitro. The present study reports other complications that were not predicted in laboratory studies.

Clinical outcomes of BRYAN cervical disc arthroplasty: a prospective, randomized, controlled, multicenter trial with 24-month follow-up.

Study Design/Setting Prospective, randomized, 3-center, clinical trial. Objective To prospectively compare the outcomes of cervical arthroplasty with the BRYAN Cervical Disc Prosthesis (Medtronic Sofamor Danek, Inc, Memphis, TN) to anterior cervical discectomy and fusion (ACDF). Summary of Background Data Surgical treatment of cervical disc pathology commonly involves techniques that employ discectomy and fusion (ACDF). This “gold-standard” technique has demonstrated good clinical and radiographic outcomes. Common adverse effects of this procedure are associated with the adjacent level degeneration and bone-graft harvest. Several investigators have independently reported successful short-term outcomes with the BRYAN Cervical Disc Prosthesis. In addition, a significant body of knowledge has been collected regarding the wear patterns and adjacent level effects of this device in human and animal models. Methods As part of an FDA IDE trial, 3 centers collected prospective outcomes data on 115 patients randomized in a 1:1 ratio to ACDF (Control group) or arthroplasty with the BRYAN Cervical Disc Prosthesis (Investigational group). Results Demographic and surgical data were generally similar in the 2 populations. Outcomes data collected at routine postoperative intervals for 24 months demonstrated that the Investigational group had statistically significant (P<0.05) improvements as assessed by the Neck Disability Index, the Neck Pain Score, and SF-36 Physical component scores. The improvement in the Mental Component Subscore values for the BRYAN and control groups was equivalent at 24 months (P=0.055). Arm pain relief was similar in both groups (P=0.152). During the course of the 2-year follow-up, 4 patients in the Control group required surgical intervention and 3 patients in the Investigational group required ACDF for adjacent level disease. Conclusions At 24 months, cervical arthroplasty with the BRYAN Cervical Disc Prosthesis compares favorably with ACDF as defined by standard outcomes scores.

Corpectomy versus laminoplasty for multilevel cervical myelopathy: an independent matched-cohort analysis.

Study Design. Matched patient cohorts using retrospective chart and radiographic review with independent clinical and radiographic follow-up were reviewed. Objective. To compare the clinical and radiographic outcomes of multilevel corpectomy and laminoplasty using an independent matched-cohort analysis. Summary of Background Data. The treatment of choice for multilevel cervical myelopathy remains a matter of investigation. For the decompression of three or more motion segments, multilevel corpectomy and laminoplasty have proven effective while avoiding the pitfalls of laminectomy. Direct clinical comparisons of these two procedures are few in number and are limited by the heterogeneity in their patient groups. Methods. Medical records of all patients treated for multilevel cervical myelopathy with either multilevel corpectomy or laminoplasty between 1994 and 1999 at the Emory Spine Center were reviewed. From a pool of 38 patients meeting stringent inclusion and exclusion criteria, 13 patients who underwent multilevel corpectomy were blindly matched with 13 patients who underwent laminoplasty based on known prognostic criteria. A single physician independently evaluated each patient and their radiographs at their latest follow-up appointment. Results. The cohorts were well matched by age, duration of symptoms, severity of myelopathy (Nurick grade), and preoperative sagittal alignment (C2–C7). Mean operative time, blood loss, and hospital stay were nearly identical. The mean follow-up for multilevel corpectomy and laminoplasty were 49 and 40 months, respectively. Improvement in function averaged 1.6 Nurick grades after laminoplasty and 0.9 grades after multilevel corpectomy (P > 0.05). Subjective improvements in strength, dexterity, sensation, pain, and gait were similar for the two operations. The prevalence of axial discomfort at the latest follow-up was the same for each cohort, but the analgesic requirements tended to be greater for patients who underwent multilevel corpectomy. Sagittal motion from C2 to C7 decreased by 57% after multilevel corpectomy and by 38% after laminoplasty. One complication (C6–C7 herniated nucleus pulposus [HNP] requiring anterior discetomy with fusion) occurred in the laminoplasty group. Multilevel corpectomy complications included progression of myelopathy, nonunion, persistent dysphagia, persistent dysphonia, and subjacent motion segment ankylosis. Conclusions. Both multilevel corpectomy and laminoplasty reliably arrest myelopathic progression in multilevel cervical myelopathy and can lead to significant neurologic recovery and pain reduction in a majority of patients. Surprisingly, the laminoplasty cohort tended to require less pain medication at final follow-up than did the multilevel corpectomy cohort. Given this and the higher prevalence of complications among multilevel corpectomy patients, it is believed that laminoplasty may be the preferred method of treatment for multilevel cervical myelopathy in the absence of preoperative kyphosis.

Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: an independent matched cohort analysis.

Study Design. A matched cohort clinical and radiographic retrospective analysis of laminoplasty and laminectomy with fusion for the treatment of multilevel cervical myelopathy. Objectives. To compare the clinical and radiographic outcomes of two procedures increasingly used to treat multilevel cervical myelopathy. Summary of Background Data. Traditional methods of treating multilevel cervical myelopathy (laminectomy and corpectomy) are reported to have a notable frequency of complications. Laminoplasty and laminectomy with fusion have been advocated as superior procedures. A comparative study of these two techniques has not been reported. Methods. Medical records of all patients treated for multilevel cervical myelopathy with either laminoplasty or laminectomy with fusion between 1994 and 1999 at our institution were reviewed. Thirteen patients that underwent laminectomy with fusion were matched with 13 patients that underwent laminoplasty. All patients and radiographs were independently evaluated at latest follow-up by a single physician. Results. Cohorts were well matched based on patient age, duration of symptoms, and severity of myelopathy (Nurick grade) before surgery. Mean independent follow-up was similar (25.5 and 26.2 months). Both objective improvement in patient function (Nurick score) and the number of patients reporting subjective improvement in strength, dexterity, sensation, pain, and gait tended to be greater in the laminoplasty cohort. Whereas no complications occurred in the laminoplasty cohort, there were 14 complications in 9 patients that underwent laminectomy with fusion patients. Complications included progression of myelopathy, nonunion, instrumentation failure, development of a significant kyphotic alignment, persistent bone graft harvest site pain, subjacent degeneration requiring reoperation, and deep infection. Conclusions. The marked difference in complications and functional improvement between these matched cohorts suggests that laminoplasty may be preferable to laminectomy with fusion as a posterior procedure for multilevel cervical myelopathy.

Nicotine on the revascularization of bone graft. An experimental study in rabbits.

Study Design In 24 rabbits, the authors transplanted autologous cancellous bone to the anterior chamber of the eye. Half of the rabbits received nicotine and half received placebo (albumin) from mini-osmotic pumps that were implanted subcutaneously. Revascularization of the bone graft was evaluated postoperatively using ophthalmology slit-lamp and fluorescein anglography, and after sacrifice using microvascular silicone injection and histology. Objectives The hypothesis that nicotine inhibits the revascularization of bone graft because of its pharmacologic action on the microvasculature was tested. Summary of Background Data. Pseudoarthrosis after spinal fusion occurs more frequently in smokers as compared with nonsmokers. Methods. Observations of the bone graft were made regarding the time after implantation when vessels within the graft were noted and the pattern of these vessels. Revascularization of the graft was graded based on the observed percent area of fluorescence after injection of fluorescein. Serum levels of nicotine were measured weekly. Colored silicone was injected at sacrifice to fix the vasculature of the bone graft. Histologic analysis of undecalcified sections was performed. Results. Nicotine, as compared with placebo was associated with delayed revascularization within the graft, a smaller percent area of revascularization, and a larger number of grafts showing necrosis. Conclusions. Nicotine inhibits, but does not prevent, the revascularization of cancellous bone grafts. Inhibition of early revascularization by nicotine is proposed as the pathophysiologic mechanism by which smoking may adversely affect the healing of spinal fusions.

Bone grafting alternatives in spinal surgery

BACKGROUND CONTEXT Bone grafting is used to augment bone healing and provide stability after spinal surgery. Autologous bone graft is limited in quantity and unfortunately associated with increased surgical time and donor-site morbidity. Alternatives to bone grafting in spinal surgery include the use of allografts, osteoinductive growth factors such as bone morphogenetic proteins and various synthetic osteoconductive carriers. PURPOSE Recent research has provided insight into methods that may modulate the bone healing process at the cellular level in addition to reversing the effects of symptomatic disc degeneration, which is a potentially disabling condition, managed frequently with various fusion procedures. With many adjuncts and alternatives available for use in spinal surgery, a concise review of the current bone grafting alternatives in spinal surgery is necessary. STUDY DESIGN/SETTING A systematic review of the contemporary English literature on bone grafting in spinal surgery, including abstract information presented at national meetings. METHODS Bone grafting alternatives were reviewed as to their efficacy in extending or replacing autologous bone graft sources in spinal applications. RESULTS Alternatives to autologous bone graft include allograft bone, demineralized bone matrix, recombinant growth factors and synthetic implants. Each of these alternatives could possibly be combined with autologous bone marrow or various growth factors. Although none of the presently available substitutes provides all three of the fundamental properties of autograft bone (osteogenicity, osteoconductivity and osteoinductivity), there are a number of situations in which they have proven clinically useful. CONCLUSIONS Alternatives to autogenous bone grafting find their greatest appeal when autograft bone is limited in supply or when acceptable rates of fusion may be achieved with these substitutes (or extenders) despite the absence of one or more of the properties of autologous bone graft. In these clinical situations, the morbidity of autograft harvest is reasonably avoided. Future research may discover that combinations of materials may cumulatively result in the expression of osteogenesis, osteoinductivity and osteoconductivity found in autogenous sources.

Artificial disc versus fusion: a prospective, randomized study with 2-year follow-up on 99 patients.

Study Design. A total of 115 patients were randomized in a 1:1 ratio to a Bryan artificial disc replacement (56) or an anterior cervical fusion with allograft and a plate (59). Objective. The purpose of this study is to examine the functional outcome and radiographic results of this prospective, randomized trial to determine the role of the Bryan artificial cervical disc replacement for patients with 1-level cervical disc disease. Summary of Background Data. Artificial cervical disc replacement has become an option for cervical radiculopathy. Previous studies have evaluated the efficacy of this alternative without the scientific rigor of a concurrent control population. This study is a pooled data set from 3 centers involved in the U.S. FDA Investigational Device Exemption trial evaluating the Bryan artificial cervical disc. Methods. The purpose of this study is to examine the functional outcome and radiographic results of this prospective, randomized trial to determine the role of the Bryan artificial cervical disc replacement for patients with 1-level cervical disc disease; 12-month follow-up is available for 110 patients and 24 month follow-up complete for 99 patients. There are 30 males and 26 females in the Bryan group and 32 males and 27 females in the fusion group. The average age was 43 years (Bryan) and 46 years (fusion). Disability and pain were assessed using the Neck Disability Index (NDI) and the Visual Analog Scale (VAS) of the neck and of the arm pain. SF-36 outcome measures were obtained including the physical component as well as the mental component scores. Range of motion was determined by independent radiologic assessment of flexion-extension radiographs. We report a prospective, randomized study comparing the functional outcome of cervical disc replacement to an anterior cervical fusion with results of 99 patients at 2 years. Prospective data were collected before surgery and at 6 weeks, 3, 6, 12, and 24 months after surgery. Results. The average operative time for the control group was 1.1 hours and the Bryan Group 1.7 hours.Average blood loss was 49 mL (control) and 64 mL (Bryan). Average hospital stay was 0.6 days (control) and 0.9 days (Bryan). The mean NDI before surgery was not statistically different between groups: 47 (Bryan) and 49 (control). Twelve-month follow-up NDI is 10 (Bryan) and 18 (control) (P = 0.013). At 2-year follow-up, NDI for the Bryan group is 11 and the control group is 20 (P = 0.005). The mean arm pain VAS before surgery was 70 (Bryan) and 71 (control). At 1-year follow-up, Bryan arm pain VAS was 12 and control 23 (P = 0.031). At 2-year follow-up, the average arm pain VAS for the Bryan group was 14 and control 28 (P = 0.014). The mean neck pain VAS before surgery was 72 (Bryan) and 73 (control). One-year follow-up scores were 17 (Bryan) and 28 (control) (P = 0.05). At 2 years: 16 (Bryan) and 32 (control) (P = 0.005). SF-36 scores: Physical component- Before surgery Bryan 34 and control 32. At 24 months: Bryan 51 and control 46 (P = 0.009). More motion was retained after surgery in the disc replacement group than the plated group at the index level (P < 0.006 at 3, 6, 12, and 24 months). The disc replacement group retained an average of 7.9° of flexion-extension at 24 months. In contrast, the average range of motion in the fusion group was 0.6° at 24 months. There were 6 additional operations in this series: 4 in the control group and 2 in the investigational group. There were no intraoperative complications, no vascular or neurologic complications, no spontaneous fusions, and no device failures or explantations in the Bryan cohort. Conclusion. The Bryan artificial disc replacement compares favorably to anterior cervical discectomy and fusion for the treatment of patients with 1-level cervical disc disease. At the 2-year follow-up, there are statistically significant differences between the groups with improvements in the NDI, the neck pain and arm pain VAS scores, and the SF-36 physical component score in the Bryan disc population.

Expansive midline T-saw laminoplasty (modified spinous process-splitting) for the management of cervical myelopathy.

Study Design. The authors developed a method of spinous process‐splitting laminoplasty using a threadwire saw in a prospective study of 25 patients with cervical myelopathy. This report describes the surgical technique and the results of the expansive midline laminoplasty performed with an threadwire saw. Objectives. To compare the efficacy of midline, threadwire‐saw laminoplasty with that of the original spinous process‐splitting laminoplasty. Summary of Background Data. The spinous process‐splitting laminoplasty was described by Kurokawa in 1982. Although the procedure has a number of theoretical and practical advantages, it has not been widely used because of technical difficulties. Methods. Twenty‐five patients who underwent expansive, midline, threadwire‐saw laminoplasty from C3 to C7 for cervical myelopathy were studied. The threadwire saw was used to split the spinous processes. The mean follow‐up period was 34 months. Neurologic results were evaluated with pre‐ and postoperative scores, and recovery rates were evaluated by methods described in previous reports using the Japanese Orthopaedic Association scoring system. Radiographic data analyzed included plain radiographs and computed tomography scans. The duration of surgery and the amount of blood lost during this procedure using the threadwire saw were compared with the duration and blood loss that occurred during the original Kurokawas procedure using a burr. Results. In all cases, good enlargement of the cervical canal was achieved. The mean increase in cervical cross‐sectional area was 36.1%, according to computed tomography scans. No dural tears occurred, and no patients experienced any decrease in neurologic function. The neurologic recovery rate was 72%, which was almost same as the neurologic recovery rate in the original procedure. Using the threadwire saw, the mean duration of surgery was 63 minutes shorter and the mean blood loss was 70 cc less than in procedures using burrs Conclusions. The application of the threadwire saw to split the spinous processes made Kurokawas procedure simpler, faster, and safer.