Comparison of the effectiveness and safety of bioactive glass ceramic to allograft bone for anterior cervical discectomy and fusion with anterior plate fixation.

Recently, a bioactive glass ceramic (BGC) has been developed for use as intervertebral cages for anterior cervical discectomy and fusion (ACDF). However, the effectiveness and safety of BGC cages remain to be evaluated. We completed a retrospective comparison of the radiological and clinical outcomes of 36 patients (52 levels) who underwent ACDF with a BGC cage and 35 patients (54 levels) using allograft bone. The following variables were compared between the two groups: the visual analog (VAS) neck and arm pain score and the neck disability index (NDI), measured before surgery and 1 year after; the change in Cobb's angle, between the C2 and C7 vertebrae, the global sagittal angle, and disc height compared from before surgery to 1 year after; and the rate of spinal fusion and cage subsidence at 1 and 2 years after surgery. The VAS and NDI scores were not different between the two groups. Similarly, the spinal fusion rate was not different between the BGC and allograft bone group at 1 year (73% and 87%, respectively; p = 0.07) and 2 years (94% and 91%, respectively; p = 0.54) after surgery. However, the rate of cage subsidence was higher in the allograft bone (43%) than the BGC (19%) group (p = 0.03), as was the rate of instrument-related failure (p = 0.028), with a specifically higher incidence of implant fracture or failure in the allograft bone group (p = 0.025). Overall, our findings indicate that BGC cages provide a feasible and safe alternative to allograft bone for ACDF.

Five-Year Follow-Up of a Prospective, Randomized Trial Comparing Two Lumbar Total Disc Replacements.

STUDY DESIGN: This was a prospective, randomized, controlled, multicenter study. OBJECTIVE: The purpose of this study was to compare outcomes of two lumbar total disc replacements (TDRs) at 5-year follow-up and report results of serum ion level analysis in a subgroup of patients receiving a metal-on-metal implant. SUMMARY OF BACKGROUND DATA: Lumbar TDR has been compared with fusion in several randomized studies, finding TDR noninferior to fusion and superior on some measures. Receiving less attention has been comparing TDR devices. Additionally, there is concern about metal-on-metal implants, with little data available for spine devices. METHODS: The study included 204 patients receiving Kineflex-L (investigational) and 190 receiving CHARITÉ (control). Outcome measure included Oswestry Disability Index, visual analog pain scales (VAS), patient satisfaction, neurological status, complications, reoperations, and a composite success score. Radiographic assessment included range of motion, subsidence, and heterotrophic ossification. In 32 investigational patients, serum ion analysis was performed for cobalt and chromium. These values were compared with Medicines and Healthcare Products Regulatory Agency values to merit monitoring total hip replacement patients for potential wear problems. RESULTS: Mean Oswestry and VAS scores in both groups improved significantly by 6 weeks and remained improved during 5-year follow-up (Oswestry Disability Index, scores in both groups were approximately 60 preoperatively vs. 20 at 2- and 5-year follow-up; P < 0.01; VAS scores improved >50% by 6 weeks and remained significantly improved; P < 0.05). Approximately 11% of both groups underwent reoperation. Radiographic analysis found segmental range of motion decreased at 3 month, then increased through 24 months, and was maintained thereafter. Serum ion level analysis found the greatest mean value at any follow-up point was less than 20% of Medicines and Healthcare Products Regulatory Agency recommended minimum value to merit monitoring hip replacement patients. CONCLUSION: This prospective, randomized study comparing two TDRs found no significant differences in outcomes during 5-year follow-up. Both provided statistically significant improvements by 6 weeks that were maintained. This results support other studies. Serum ion levels in TDR patients were well below the recommended threshold levels to merit monitoring.

Comparison of 2 lumbar total disc replacements: results of a prospective, randomized, controlled, multicenter Food and Drug Administration trial with 24-month follow-up.

STUDY DESIGN: This was a prospective, randomized, controlled multicenter study with 24-month follow-up. OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy in a Food and Drug Administration Investigation Device Exemption of a new lumbar total disc replacement (TDR) by comparing it to an earlier TDR approved for sale. SUMMARY OF BACKGROUND DATA: Randomized trials have reported TDR to produce results similar or superior to lumbar fusion. Results for various TDRs seem to be similar, but differences in study design and outcome measures pose challenges in definitively comparing devices. The purpose of this study was to perform a direct comparison of 2 lumbar TDRs in a prospective, randomized trial. METHODS: TDR was performed in 457 patients from 21 sites (261 patients in the investigational group (Kineflex-L Disc; metal-on-metal design anchored with keels, 204 randomized and 57 nonrandomized training cases), and 196 in the control group (CHARITE artificial disc; metal with polyethylene core with teeth for anchoring; 190 randomized and 6 nonrandomized training cases). All patients were treated nonoperatively for single-level symptomatic disc degeneration for at least 6 months prior to surgery. Perioperative data were collected. Clinical outcome data were collected prospectively, as approved by the Food and Drug Administration, through 24-month follow-up. Primary outcome measures used were the Oswestry Disability Index, visual analogue scales assessing pain, patient satisfaction, and reoperations. Success was defined to be at least 15-point improvements in Oswestry Disability Index scores, no reoperation, and no major adverse events. Radiographical measures included range of motion, disc space height, and assessment for device migration, subsidence, and fusion at the TDR level. RESULTS: There were no significant differences between the groups when comparing operative time, blood loss, or length of hospital stay. Both groups improved significantly on Oswestry Disability Index and visual analogue scale scores (P < 0.01) with no differences between the groups. Success rates were similar (68.1% investigational vs. 67.4% control). At 24-month follow-up, 94.1% of the investigational group and 91.9% of controls were satisfied with outcome. Reoperation was performed in 10.3% of the investigational group and 8.4% of the control group. CONCLUSION: This prospective, randomized, controlled study comparing 2 TDRs, the first to the authors' knowledge, found the devices produced very similar clinical outcomes. Both groups improved significantly by 6 weeks postoperatively and remained improved throughout follow-up with a high patient satisfaction rate.

Allogeneic morphogenetic protein vs. recombinant human bone morphogenetic protein-2 in lumbar interbody fusion procedures: a radiographic and economic analysis.

BACKGROUND: Since the introduction of rhBMP-2 (Infuse) in 2002, surgeons have had an alternative substitute to autograft and its related donor site morbidity. Recently, the prevalence of reported adverse events and complications related to the use of rhBMP-2 has raised many ethical and legal concerns for surgeons. Additionally, the cost and decreasing reimbursement landscape of rhBMP-2 use have required identification of a viable alternative. Osteo allogeneic morphogenetic protein (OsteoAMP) is a commercially available allograft-derived growth factor rich in osteoinductive, angiogenic, and mitogenic proteins. This study compares the radiographic fusion outcomes between rhBMP-2 and OsteoAMP allogeneic morphogenetic protein in lumbar interbody fusion spine procedures. METHODS: Three hundred twenty-one (321) patients from three centers underwent a transforaminal lumbar interbody fusion (TLIF) or lateral lumbar interbody fusion (LLIF) procedure and were assessed by an independent radiologist for fusion and radiographically evident complications. The independent radiologist was blinded to the intervention, product, and surgeon information. Two hundred and twenty-six (226) patients received OsteoAMP with autologous local bone, while ninety-five (95) patients received Infuse with autologous local bone. Patients underwent radiographs (x-ray and/or CT) at standard postoperative follow-up intervals of approximately 1, 3, 6, 12, and 18 months. Fusion was defined as radiographic evidence of bridging across endplates, or bridging from endplates to interspace disc plugs. Osteobiologic surgical supply costs were also analyzed to ascertain cost differences between OsteoAMP and rhBMP-2. RESULTS: OsteoAMP produced higher rates of fusion at 6, 12, and 18 months (p ≤ 0.01). The time required for OsteoAMP to achieve fusion was approximately 40% less than rhBMP-2 with approximately 70% fewer complications. Osteobiologic supply costs were 80.5% lower for OsteoAMP patients (73.7% lower per level) than for rhBMP-2. CONCLUSIONS: Results of this study indicate that OsteoAMP is a viable alternative to rhBMP-2 both clinically and economically when used in TLIF and LLIF spine procedures.

Myelographic evaluation of cervical spondylosis: patient tolerance and complications.

STUDY DESIGN: Retrospective chart review of documented adverse events in 637 consecutive patients after computed tomogram myelography and follow-up interview of the most recent 100 of these patients. OBJECTIVES: This study assessed documented prevalence of adverse events after diagnostic myelography in cervical spondylotic patients and compared with perceived adverse events and satisfaction in a subset of the same cohort of patients. SUMMARY OF BACKGROUND DATA: There are some data that suggest complimentary benefits of myelography to magnetic resonance imaging. However, given the invasive nature of myelography, there are little data documenting the adverse events and patient experience with myelography to guide informed consent and physician choice of this study. METHODS: We analyzed the records of 637 consecutive patients (364 males and 273 females) after myelography. Five hundred forty-four patients (group 1) had a cervical approach and 93 (group 2) had a lumbar approach. The last 100 consecutive patients (85 in group 1 and 15 in group 2) were asked questions that addressed patient perceived adverse reactions, pain levels, and satisfaction. RESULTS: There was a 4.4% (28/637) prevalence of documented abnormal reactions. Group 1 had a 4.9% (25/506) prevalence of adverse reactions compared with 3.4% (3/89) in group 2. Overall 6.6% (42/637) had to have their myelographic procedures converted. Group 1 had 7% (38/544) converted to the lumbar approach group 2 had 4.3% (4/93) converted to the cervical approach. Thirty percent of the 100 patients interviewed felt they had an unexpected reaction (28 group 1 and 2 group 2). When interviewed, 14% of patients had maximum pain scores of 10 during the procedure and 8% (all group 1) felt worse pain after the procedure was completed. Six group 1 and 2 group 2 patients would not have the procedure again even when recommended by the surgeon. There was no statistically significant difference between complication rates, conversion rates, or patient perceived unexpected reactions between the 2 groups (beta=0.90). CONCLUSIONS: This paper demonstrated the discrepancy between documented adverse events with computed tomogram myelography and patient reported tolerance as recorded by telephone follow-up. The cervical approach had a greater degree of patient perceived discomfort and a trend toward higher documented and patient reported adverse events and rate of approach conversion to a lumbar approach (P>0.5). When choosing myelography to evaluate patients with cervical spondylosis, the surgeon should consider the low patient tolerance and frequent adverse reactions that often go undocumented.

Thromboembolic disease after combined anterior/posterior reconstruction for adult spinal deformity: a prospective cohort study using magnetic resonance venography.

STUDY DESIGN: Thromboembolic disease (TED) after anterior/posterior spinal reconstructions was prospectively evaluated in 66 consecutive patients. OBJECTIVE: Determine the incidence of TED after anterior/posterior spinal reconstruction. SUMMARY OF BACKGROUND DATA: Few studies have examined the rate of TED after potentially high-risk combined anterior/posterior reconstructions. Magnetic resonance venography (MRV) is more effective at detecting pelvic deep venous thrombosis (DVT) than conventional screening, but has not been used in these patients. METHODS: We undertook a prospective cohort study of 66 consecutive adult patients (mean, 52.7 +/- 9.6 years) undergoing combined anterior/posterior spinal reconstructions for spinal deformity. All patients received only mechanical DVT prophylaxis. After surgery, MRV and bilateral lower extremity Doppler ultrasounds were obtained to screen for DVT, and contrast-enhanced spiral computed tomography scans were obtained for clinical suspicion of pulmonary embolism (PE). RESULTS: The total incidence of postoperative TED was 13.6% (9 patients). The overall rate of DVT was 9.1% (6 patients), one-third occurring in the pelvis. PE developed in 7.6% (5 patients). In 2 patients, PE developed less than 48 hours after positive dopplers. In 3 patients, PE developed despite negative screening studies. Right-sided thoracoabdominal approaches were associated with an increased risk of developing DVT (P = 0.03, Odds Ratio 9.8), PE (P = 0.01, Odds Ratio 20), and TED (P = 0.004, Odds Ratio 12). CONCLUSION: We report a high rate of TED after extensive anterior/posterior spinal reconstructions, for which a right-sided thoracoabdominal approach is an independent risk factor and screening ineffective at preventing PE. These patients should be considered at high risk for postoperative TED.

Use of spinous processes to determine drill trajectory during placement of lateral mass screws: a cadaveric analysis.

OBJECTIVE: Prior cadaveric research showed that the lateral mass and facets are landmarks to determine the initial starting point for lateral mass screws and that the optimum screw trajectory was 30 degrees lateral and 15 degrees cephalad. The missing link was an intraoperative landmark to guide the trajectory for drilling according to these angles. The authors hypothesized that spinous processes can be used to guide the trajectory for lateral mass screw placement. METHODS: The authors analyzed 144 lateral masses of 72 cervical vertebrae in 18 cadavers (7 males and 11 females). The lateral and cephalocaudad angles were measured for each lateral mass from C3 to C6 while using the spinous processes of the adjacent three caudad vertebrae at each level to guide the starting trajectories for a total of 864 angles. The lateral and cephalad trajectory angles at each spinous process relative to the starting hole were compared with 30 degrees and 15 degrees . For each angle measured at a particular level, the same starting hole was used in the lateral mass, and the superolateral cortex of each spinous process was the most medial point. RESULTS: When drilling for the C3 and C4 lateral mass screws, the C4 and C5 spinous processes provided an accurate starting point, respectively, for the lateral angle but moderately overestimated the cephalocaudad angle. For C5 and C6 lateral mass screws, the C6 and C7 spinous processes provided an accurate starting point, respectively, for both the lateral and the cephalocaudad angles. CONCLUSION: The spinous processes can be an accurate local anatomic guide for lateral mass screw trajectory and will allow greater safety while drilling before performing laminectomies. These guides may change in patients with cervical spinal deformities.

Cervicothoracic extension osteotomy for chin-on-chest deformity in ankylosing spondylitis.

BACKGROUND: Chin-on-chest deformity is a disabling manifestation of ankylosing spondylitis. Surgical treatment consists of extension osteotomy at the cervicothoracic junction. The purpose of this study was to characterize the clinical presentation of this deformity and to determine the long-term functional and radiographic outcomes of treatment. METHODS: The medical records and radiographs of all twenty-six patients treated with cervicothoracic extension osteotomy by one of us between 1976 and 2001 were retrospectively reviewed. Three patients died during the two-year-minimum follow-up period. The remaining twenty-three patients were followed for an average of 4.5 years (range, two years to twenty-one years and ten months). RESULTS: The mean sagittal correction was 38 degrees. Delayed union in two patients and additional cervical trauma in two others resulted in partial loss of the initial correction. Quadriplegia developed in one patient, who died as a result of subluxation at the osteotomy site. Five patients had irritation of the eighth cervical nerve root postoperatively. CONCLUSIONS: Extension osteotomy can reliably improve sagittal alignment and horizontal gaze as well as decrease neck pain, eating difficulties, and neurologic abnormalities. Internal fixation is recommended to prevent subluxation, delayed union, nonunion, loss of correction, or neurologic injury. There is a risk of death or catastrophic neurologic injury from the procedure.

Degenerative disorders of the lumbar and cervical spine.

Degenerative disorders in the spine are normal, age-related phenomena and largely asymptomatic in most cases. Conservative management of lumbar and cervical spondylosis is the mainstay of treatment, and most patients with symptomatic degenerative changes respond appropriately with nonsurgical management. Surgical intervention can be considered an appropriate and viable option when conservative measures have failed. Treatment options should always be directed toward the specific nature and location of the patient's individual pathology. Although current standards in the surgical management of lumbar and cervical degenerative disorders include discectomy, neural decompression, and instrumented spinal arthrodesis, new approaches that address this often-challenging clinical entity are on the horizon.

Ossification of the posterior longitudinal ligament. Results of anterior cervical decompression and arthrodesis in sixty-one North American patients.

BACKGROUND: Ossification of the posterior longitudinal ligament is commonly associated with cervical myelopathy. Surgical treatment is a matter of controversy. We report on a series of patients who were managed with anterior cervical decompression and arthrodesis for the treatment of cervical myelopathy associated with ossification of the posterior longitudinal ligament. METHODS: We retrospectively reviewed the records for all sixty-five patients who had been managed with anterior decompression and arthrodesis for the treatment of cervical ossification of the posterior longitudinal ligament and associated neurologic compression from 1982 to 2001. Sixty-one patients (thirty-nine men and twenty-two women) were followed for at least two years (or until the time of death). The average number of vertebrae resected was 2.2. The average duration of follow-up for the sixty surviving patients was four years (range, two years to fifteen years and four months). The preoperative, six-week postoperative, and final follow-up clinical status (including neurological function as assessed with the Nurick grading system) was recorded for each patient. RESULTS: Fifty-six of the sixty-one patients had neurological improvement, with an average improvement of 1.5 Nurick grades at the time of the final follow-up. Eight patients had absent dura at the time of surgery and, of these, five had development of a cerebrospinal fluid fistula. Eight patients had development of new neurological signs and/or symptoms in the upper extremity postoperatively. Eight patients required reoperation because of a painful pseudarthrosis (one patient), strut-graft dislodgment (three), cerebrospinal fluid leakage (three), or compression of a nerve root caudad to the area of the original procedure (one). One patient died as the result of cardiac arrest on the third postoperative day. Fifty-eight patients had an osseous fusion, one had an asymptomatic nonunion, and one had a symptomatic pseudarthrosis that was treated with revision surgery. CONCLUSIONS: Anterior decompression and arthrodesis is an effective way to achieve pain relief and neurological improvement in North American patients of non-Asian descent who have cervical myelopathy associated with ossification of the posterior longitudinal ligament. The risk of durocutaneous fistula, graft dislodgment, and postoperative neurological symptoms appears to be high in patients with cervical myelopathy associated with this condition.

Fusionless scoliosis surgery.

PURPOSE OF REVIEW: Severe spinal deformity in young children is a formidable challenge for optimal treatment. Standard interventions for adolescents and adults, including spinal deformity correction and fusion, may not be appropriate for young patients with considerable growth remaining. Alternate surgical options that provide deformity correction and protect the growth remaining in the spine are needed to treat this population of patients best. RECENT FINDINGS: Several groups have reported very exciting advances in the field of deformity spine surgery. Updated findings concerning the successful implementation of growing rods have revived this technique as a viable option for preserving near normal growth of the spine. New techniques have also been recently described, including vertebral stapling that produces asymmetric and corrective growth of the concavity of a deformity, and vertical expandable prosthetic titanium rib instrumentation that indirectly corrects spine deformity and protects spine growth remaining to treat an associated thoracic insufficiency syndrome. SUMMARY: New techniques and instrumentation at the disposal of spine surgeons allow the treatment of this challenging patient population to approach the goals of deformity correction and maintenance with preservation of potential growth. Preliminary outcomes from the different techniques are promising, but further investigation, including long-term follow-up, is necessary.