Robert Banco

Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of lumbar total disc replacement with the CHARITÉ artificial disc versus lumbar fusion: Five-year follow-up

BACKGROUND CONTEXT The CHARITE artificial disc, a lumbar spinal arthroplasty device, was approved by the United States Food and Drug Administration in 2004 based on two-year safety and effectiveness data from a multicenter, prospective, randomized investigational device exemption (IDE) study. No long-term, randomized, prospective study on the CHARITE disc or any other artificial disc has been published to date. PURPOSE The purpose of this study was to compare the safety and effectiveness at the five-year follow-up time point of lumbar total disc replacement using the CHARITE artificial disc (DePuy Spine, Raynham, MA) with that of anterior lumbar interbody fusion (ALIF) with BAK cages and iliac crest autograft, for the treatment of single-level degenerative disc disease from L4 to S1, unresponsive to nonoperative treatment. STUDY DESIGN/SETTING Randomized controlled trial-five-year follow-up. PATIENT SAMPLE Ninety CHARITE patients and 43 BAK patients. OUTCOME MEASURES Self-reported measures: visual analog scale (VAS); validated Oswestry disability index (ODI version 1.0); Short-Form 36 Questionnaire, and patient satisfaction. Physiologic measures: radiographic range of motion, disc height, and segmental translation. Functional measures: work status. METHODS Of the 375 subjects enrolled in the CHARITE IDE trial, 277 were eligible for the five-year study and 160 patients thereof completed the five-year follow-up. The completers included 133 randomized patients. Overall success was defined as improvement> or =15 pts in ODI vs. baseline, no device failure, absence of major complications, and maintenance or improvement of neurological status. Additional clinical outcomes included an ODI questionnaire as well as VAS, SF-36, and patient satisfaction surveys. Work status was tracked for all patients. Safety assessments included occurrence and severity of adverse events and device failures. Radiographic analyses such as index- and adjacent-level range of motion, segmental translation, disc height, and longitudinal ossification were also carried out. RESULTS Overall success was 57.8% in the CHARITE group vs. 51.2% in the BAK group (Blackwelders test: p=0.0359, Delta=0.10). In addition, mean changes from baseline for ODI (CHARITE: -24.0 pts vs. BAK: -27.5 pts), VAS pain scores (CHARITE: -38.7 vs. BAK: -40.0), and SF-36 questionnaires (SF-36 Physical Component Scores [PCS]: CHARITE: 12.6 pts vs. BAK: 12.3 pts) were similar across groups. In patient satisfaction surveys, 78% of CHARITE patients were satisfied vs. 72% of BAK patients. A total of 65.6% patients in the CHARITE group vs. 46.5% patients in the BAK group were employed full-time. This difference was statistically significant (p=0.0403). Long-term disability was recorded for 8.0% of CHARITE patients and 20.9% of BAK patients, a difference that was also statistically significant (p=0.0441). Additional index-level surgery was performed in 7.7% of CHARITE patients and 16.3% of BAK patients. Radiographic findings included operative and adjacent-level range of motion (ROM), intervertebral disc height and segmental translation. At the five-year follow-up, the mean ROM at the index level was 6.0 degrees for CHARITE patients and 1.0 degrees for BAK patients. Changes in disc height were also similar for both CHARITE and BAK patients (0.7 mm for both groups, p=0.9827). Segmental translation was 0.4 and 0.8mm in patients implanted with CHARITE at L4-L5 vs. L5-S1, respectively, and 0.1mm in BAK patients. CONCLUSIONS The results of this five-year, prospective, randomized multicenter study are consistent with the two-year reports of noninferiority of CHARITE artificial disc vs. ALIF with BAK and iliac crest autograft. No statistical differences were found in clinical outcomes between groups. In addition, CHARITE patients reached a statistically greater rate of part- and full-time employment and a statistically lower rate of long-term disability, compared with BAK patients. Radiographically, the ROMs at index- and adjacent levels were not statistically different from those observed at two-years postsurgery.

Prospective study of iliac crest bone graft harvest site pain and morbidity

BACKGROUND CONTEXT Morbidity associated with autologous bone graft harvest is an important factor in determining the utility of expensive alternatives such as recombinant bone morphogenic protein. The most frequently reported complication associated with graft harvest is chronic pain. PURPOSE To prospectively determine the degree of pain and morbidity associated with autologous iliac crest bone graft harvest and its effect on activities of daily living. STUDY DESIGN Prospective observational cohort study. PATIENT SAMPLE One hundred ten adult patients undergoing elective posterior lumbar spinal fusion surgery involving autologous iliac crest bone graft harvest. OUTCOME MEASURES Patient self-reported Visual Analog Scale (VAS) scores for pain and a study-specific questionnaire regarding activities of daily living. METHODS One hundred ten patients were prospectively enrolled. Postoperative VAS scores (0-100) for harvest site pain were obtained at 6-week, 6- and 12-month follow-up. Patients completed a 12-month questionnaire regarding the persistence of specific symptoms and resulting limitation of specific activities. RESULTS One hundred four patients were available for 1-year follow-up. Mean VAS pain scores (scale 0-100) at 6 weeks, 6 and 12 months were 22.7 (standard deviation [SD], 25.9), 15.9 (SD, 21.5), and 16.1 (SD, 24.6), respectively. At 12 months, 16.5% reported more severe pain from the harvest site than the primary surgical site, 29.1% reported numbness, and 11.3% found the degree of numbness bothersome, whereas 3.9% were bothered by scar appearance. With respect to activity limitations resulting from harvest site pain at 1 year, 15.1% reported some difficulty walking, 5.2% with employment, 12.9% with recreation, 14.1% with household chores, 7.6% with sexual activity, and 5.9% irritation from clothing. CONCLUSIONS There is a significant rate of persistent pain and morbidity from iliac crest bone graft harvest when associated with elective spine surgery. Mean pain scores progressively decline over the first postoperative year. Nevertheless, harvest site pain remains functionally limiting in a significant percentage of patients 1 year after surgery. Rates of functional limitation are higher than previously reported and may be because of increased sensitivity of the prospective study design and targeted investigation of these specific symptoms. Validity of these findings is necessarily limited by patient ability to discriminate harvest site pain from alternative sources of back and buttock pain.

Efficacy and safety of surgical decompression in patients with cervical spondylotic myelopathy: results of the AOSpine North America prospective multi-center study.

BACKGROUND Cervical spondylotic myelopathy is the leading cause of spinal cord dysfunction worldwide. The objective of this study was to evaluate the impact of surgical decompression on functional, quality-of-life, and disability outcomes at one year after surgery in a large cohort of patients with this condition. METHODS Adult patients with symptomatic cervical spondylotic myelopathy and magnetic resonance imaging evidence of spinal cord compression were enrolled at twelve North American centers from 2005 to 2007. At enrollment, the myelopathy was categorized as mild (modified Japanese Orthopaedic Association [mJOA] score ≥ 15), moderate (mJOA = 12 to 14), or severe (mJOA < 12). Patients were followed prospectively for one year, at which point the outcomes of interest included the mJOA score, Nurick grade, Neck Disability Index (NDI), and Short Form-36 version 2 (SF-36v2). All outcomes at one year were compared with the preoperative values with use of univariate paired statistics. Outcomes were also compared among the severity classes with use of one-way analysis of variance. Finally, a multivariate analysis that adjusted for baseline differences among the severity groups was performed. Treatment-related complication data were collected and the overall complication rate was calculated. RESULTS Eighty-five (30.6%) of the 278 enrolled patients had mild cervical spondylotic myelopathy, 110 (39.6%) had moderate disease, and 83 (29.9%) had severe disease preoperatively. One-year follow-up data were available for 222 (85.4%) of 260 patients. There was a significant improvement from baseline to one year postoperatively (p < 0.05) in the mJOA score, Nurick grade, NDI score, and all SF-36v2 health dimensions (including the mental and physical health composite scores) except general health. With the exception of the change in the mJOA, the degree of improvement did not depend on the severity of the preoperative symptoms. These results remained unchanged after adjusting for relevant confounders in the multivariate analysis. Fifty-two patients experienced complications (prevalence, 18.7%), with no significant differences among the severity groups. CONCLUSIONS Surgical decompression for the treatment of cervical spondylotic myelopathy was associated with improvement in functional, disability-related, and quality-of-life outcomes at one year of follow-up for all disease severity categories. Furthermore, complication rates observed in the study were commensurate with those in previously reported cervical spondylotic myelopathy series.

Perioperative and delayed complications associated with the surgical treatment of cervical spondylotic myelopathy based on 302 patients from the AOSpine North America Cervical Spondylotic Myelopathy Study

OBJECT Rates of complications associated with the surgical treatment of cervical spondylotic myelopathy (CSM) are not clear. Appreciating these risks is important for patient counseling and quality improvement. The authors sought to assess the rates of and risk factors associated with perioperative and delayed complications associated with the surgical treatment of CSM. METHODS Data from the AOSpine North America Cervical Spondylotic Myelopathy Study, a prospective, multicenter study, were analyzed. Outcomes data, including adverse events, were collected in a standardized manner and externally monitored. Rates of perioperative complications (within 30 days of surgery) and delayed complications (31 days to 2 years following surgery) were tabulated and stratified based on clinical factors. RESULTS The study enrolled 302 patients (mean age 57 years, range 29-86) years. Of 332 reported adverse events, 73 were classified as perioperative complications (25 major and 48 minor) in 47 patients (overall perioperative complication rate of 15.6%). The most common perioperative complications included minor cardiopulmonary events (3.0%), dysphagia (3.0%), and superficial wound infection (2.3%). Perioperative worsening of myelopathy was reported in 4 patients (1.3%). Based on 275 patients who completed 2 years of follow-up, there were 14 delayed complications (8 minor, 6 major) in 12 patients, for an overall delayed complication rate of 4.4%. Of patients treated with anterior-only (n = 176), posterior-only (n = 107), and combined anterior-posterior (n = 19) procedures, 11%, 19%, and 37%, respectively, had 1 or more perioperative complications. Compared with anterior-only approaches, posterior-only approaches had a higher rate of wound infection (0.6% vs 4.7%, p = 0.030). Dysphagia was more common with combined anterior-posterior procedures (21.1%) compared with anterior-only procedures (2.3%) or posterior-only procedures (0.9%) (p < 0.001). The incidence of C-5 radiculopathy was not associated with the surgical approach (p = 0.8). The occurrence of perioperative complications was associated with increased age (p = 0.006), combined anterior-posterior procedures (p = 0.016), increased operative time (p = 0.009), and increased operative blood loss (p = 0.005), but it was not associated with comorbidity score, body mass index, modified Japanese Orthopaedic Association score, smoking status, anterior-only versus posterior-only approach, or specific procedures. Multivariate analysis of factors associated with minor or major complications identified age (OR 1.029, 95% CI 1.002-1.057, p = 0.035) and operative time (OR 1.005, 95% CI 1.002-1.008, p = 0.001). Multivariate analysis of factors associated with major complications identified age (OR 1.054, 95% CI 1.015-1.094, p = 0.006) and combined anterior-posterior procedures (OR 5.297, 95% CI 1.626-17.256, p = 0.006). CONCLUSIONS For the surgical treatment of CSM, the vast majority of complications were treatable and without long-term impact. Multivariate factors associated with an increased risk of complications include greater age, increased operative time, and use of combined anterior-posterior procedures.

Anterior versus posterior surgical approaches to treat cervical spondylotic myelopathy: Outcomes of the prospective multicenter AOSpine north America CSM study in 264 patients

Study Design. A prospective observational multicenter study. Objective. To help solve the debate regarding whether the anterior or posterior surgical approach is optimal for patients with cervical spondylotic myelopathy (CSM). Summary of Background Data. The optimal surgical approach to treat CSM remains debated with varying opinions favoring anterior versus posterior surgical approaches. We present an analysis of a prospective observational multicenter study examining outcomes of surgical treatment for CSM. Methods. A total of 278 subjects from 12 sites in North America received anterior/posterior or combined surgery at the discretion of the surgeon. This study focused on subjects who had either anterior or posterior surgery (n = 264, follow-up rate, 87%). Outcome measures included the modified Japanese Orthopedic Assessment scale, the Nurick scale, the Neck Disability Index, and the Short-Form 36 (SF-36) Health Survey version 2 Physical and Mental Component Scores. Results. One hundred and sixty-nine patients were treated anteriorly and 95 underwent posterior surgery. Anterior surgical cases were younger and had less severe myelopathy as assessed by mJOA and Nurick scores. There were no baseline differences in Neck Disability Index or SF-36 between the anterior and posterior cases. Improvement in the mJOA was significantly lower in the anterior group than posterior group (2.47 vs. 3.62, respectively, P < 0.01), although the groups started at different levels of baseline impairment. The extent of improvement in the Nurick Scale, Neck Disability Index, SF-36 version 2 Physical Component Score, and SF-36 version 2 Mental Component Score did not differ between the groups. Conclusion. Patients with CSM show significant improvements in several health-related outcome measures with either anterior or posterior surgery. Importantly, patients treated with anterior techniques were younger, with less severe impairment and more focal pathology. We demonstrate for the first time that, when patient and disease factors are controlled for, anterior and posterior surgical techniques have equivalent efficacy in the treatment of CSM. Level of Evidence: 3

Risk factors for false positive transcranial motor evoked potential monitoring alerts during surgical treatment of cervical myelopathy.

Study Design. Retrospective consecutive series review. Objective. To examine performance of transcranial motor-evoked potential (TcMEP) monitoring in patients undergoing surgery for cervical myelopathy and potential risk factors for false positive alerts. Summary of Background Data. Although use of TcMEP monitoring has been increasing and has been specifically recommended in patients with cervical myelopathy, rates and risk factors for false positive alerts have not been established. Methods. Intraoperative neuromonitoring data for 52 consecutive patients undergoing surgery for cervical myelopathy were reviewed. All major TcMEP alerts were identified. Comprehensive demographic and clinical data, preoperative imaging studies, operative, and anesthesia records were reviewed. Results. Six of 52 patients (12%) experienced a major TcMEP alert consisting of sustained >80% loss of amplitude. There were no somatosensory-evoked potential (SSEP)-related alerts. In 2 cases, an intraoperative wake-up test was negative and in 3 cases, surgery was completed without a wake-up test and without recovery of TcMEP signals. No new postoperative neurologic deficits were observed in these patients. One patient with new postoperative weakness was correctly predicted by loss of TcMEP signals. No new deficit was observed in the remaining 46 patients. Statistical analysis revealed significantly higher body mass index (28.8 vs. 35.0; P = 0.032) and length of surgery (191 vs. 283 minutes; P = 0.019) in patients with false positive alerts. Conclusion. In this series of cervical myelopathy patients, sensitivity and specificity of TcMEP for detection of clinically significant intraoperative cord injury were 100% and 90%, respectively. Sensitivity and specificity of SSEP were 0% and 100%, respectively. The positive predictive value of a TcMEP alert was 17%. Possible risk factors for false positive TcMEP alerts include obesity and increased length of surgery. This study supports superior sensitivity of TcMEP compared with SSEP monitoring but identifies a relatively high false positive rate even in a selected high-risk cervical myelopathy population when this modality is applied in practice.

Computed tomography evaluation of superior-segment facet-joint violation after pedicle instrumentation of the lumbar spine with a midline surgical approach.

Study Design. Retrospective study. Objectives. To determine the frequency of pedicle screw violation of superior nonfused facet joints adjacent to the most cephalad pedicle screws after a midline approach for lumbar fusion. Summary of Background Data. Facet-joint violations have been evaluated in patients undergoing lumbar pedicle screw instrumentation and fusion with a Wiltse muscle-splitting approach, but not via the more common midline approach. Methods. Between 1995 and 2003, 204 patients underwent this procedure. Computed tomography scans (within 1 year postsurgery) were evaluated independently for superior facet-joint violation. &khgr;2 tests were used to examine bivariate associations of superior level facet-joint violation, patient age, construct level, diagnosis, and revision status for significance (P ≤ 0.05). Results. Superior-level facet-joint violation occurred in 24% of patients and 15% of screws, twice as often on the left side (P = 0.0396) than on the right, more frequently in single than in multiple-level procedures (P < 0.0001), and most frequently with the most cephalad screws at L5 (48%). We found no significant associations between violation rates and other designated parameters. Conclusion. The left side, single-level fusion, and most cephalad pedicle screws at L5 are targets for interventions to reduce pedicle violations in this procedure.

Polymorphic variation of the guanosine triphosphate cyclohydrolase 1 gene predicts outcome in patients undergoing surgical treatment for lumbar degenerative disc disease.

Study Design. Prospective observational study. Objective. To determine whether polymorphic variations of the guanosine triphosphate (GTP) cyclohydrolase 1 gene (GCH1) are associated with different outcomes in patients undergoing surgical treatment for lumbar degenerative disc disease (DDD). Summary of Background Data. GCH1, the gene encoding the rate-limiting enzyme in tetrahydrobiopterin synthesis, has been strongly implicated as a determinant of pain experience in previous animal and human studies. Methods. A total of 69 patients undergoing surgical treatment for lumbar DDD were prospectively enrolled. Genomic DNA was extracted from a venous blood sample, and DNA sequence analysis was performed of GCH1. Surgery included 65 instrumented fusions and 4 disc arthroplasty procedures. Patients were observed prospectively for 1 year following surgery. Allelic and genotype frequencies were calculated for each of 14 single nucleotide polymorphisms (SNPs). One-year postoperative Oswestry Disability Index (ODI) scores were compared to preoperative scores and the absolute change in ODI score was used to perform genetic association analyses on the basis of both individual SNP markers as well as commonly observed haplotypes for the entire gene sequence. Results. Single marker analysis revealed 1 SNP (rs998259; minor allele T) that was significantly associated with improvement in both absolute ODI score (P = 0.030) and Numerical Rating Scale back pain scores (P = 0.033) following surgery. Haplotype analysis identified a common GCH1 haplotype (“CACTTGTTTGAC”) with a sample frequency of 12.3%, which was highly associated with improvement in absolute ODI score (P = 0.04). This haplotype frequency reflects the existence of both heterozygous and homozygous individuals in the study population. The presence of 1 unit of this haplotype was associated with an improvement in postoperative ODI score of 15.34 relative to the absence of this haplotype (P = 0.04). Conclusion. Preliminary results from this pilot genetic study of patients undergoing surgery for DDD suggests that the T allele at rs998259 of GCH1 may be associated with improved outcomes 1 year following surgery.

Efficacy of silicate-substituted calcium phosphate ceramic in posterolateral instrumented lumbar fusion.

Study Design/Setting. Retrospective review of a consecutive, nonrandomized series operated on by 2 surgeons. Objective. To evaluate the clinical and radiographic effectiveness of a silicated hydroxyapatite ceramic as a bone graft substitute in a series of patients undergoing posterolateral instrumented lumbar fusion. Summary of Background Data. Newer-generation synthetic ceramics have been refined to maximize their host-graft interaction and stimulation of new tissue formation, including silicate-substitution. Methods. An independent radiologist interpreted the computed tomography images at 6, 12, and 24 months after surgery. Forty-two patients with 1- or 2-level lumbar degenerative disorders underwent posterior laminectomy (when indicated) and posterolateral fusion with instrumentation. Surgical levels included 15 patients who underwent 2-level and 27 single-level fusion procedures (57 levels operated on in total). Results. The average back pain scores improved from 5.6 ± 2.5 preoperative to 2.1 ± 2.5 at follow-up (P < 0.05). Similar results were seen with leg pain improvement from 5.8 ± 2.5 to 1.4 ± 1.9 (P < 0.05). At 6 months, 35% of levels revealed fusion, which increased to 76.2% and 76.5% at 12 and 24 months, respectively. No evidence of ectopic bone formation or osteolysis was noted. Conclusion. In this study, a silicated calcium phosphate-based ceramic has been shown to be effective as a graft substitute and eliminate the need for autogenous iliac crest bone graft. The results confirm radiographic healing in posterolateral instrumented lumbar fusion at 24-months follow-up. The clinical outcomes also substantiate significant pain improvement consistent with published data in the literature compared with other bone graft alternatives.

Mild diabetes is not a contraindication for surgical decompression in cervical spondylotic myelopathy: results of the AOSpine North America multicenter prospective study (CSM)

BACKGROUND CONTEXT Cervical spondylotic myelopathy (CSM) is a chronic spinal cord disease and can lead to progressive or stepwise neurologic decline. Several factors may influence this process, including extent of spinal cord compression, duration of symptoms, and medical comorbidities. Diabetes is a systemic disease that can impact multiple organ systems, including the central and peripheral nervous systems. There has been little information regarding the effect of diabetes on patients with coexistent CSM. PURPOSE To provide empirical data regarding the effect of diabetes on treatment outcomes in patients who underwent surgical decompression for coexistent CSM. STUDY DESIGN/SETTING Large prospective multicenter cohort study of patients with and without diabetes who underwent decompressive surgery for CSM. PATIENT SAMPLE Two hundred thirty-six patients without and 42 patients with diabetes were enrolled. Of these, 37 were mild cases and five were moderate cases. Four required insulin. There were no severe cases associated with end-organ damage. OUTCOME MEASURES Self-report measures include Neck Disability Index and version 2 of 36-Item Short Form Health Survey (SF-36v2), and functional measures include modified Japanese Orthopedic Association (mJOA) score and Nurick grade. METHODS We compared presurgery symptoms and treatment outcomes between patients with and without diabetes using univariate and multivariate models, adjusting for demographics and comorbidities. RESULTS Diabetic patients were older, less likely to smoke, and more likely to be on social security disability insurance. Patients with diabetes presented with a worse Nurick grade, but there were no differences in mJOA and SF-36v2 at presentation. Overall, there was a significant improvement in all outcome parameters at 12 and 24 months. There was no difference in the level of improvement between the patients with and without diabetes, except in the SF-36v2 Physical Functioning, in which diabetic patients experienced significantly less improvement. There were no differences in surgical complication rates between diabetic patients and nondiabetic patients. CONCLUSIONS Except for a worse Nurick grade, diabetes does not seem to affect severity of symptoms at presentation for surgery. More importantly, with the exception of the SF-36v2 Physical Functioning scores, outcomes of surgical treatment are similar in patients with diabetes and without diabetes. Surgical decompression is effective and should be offered to patients with diabetes who have symptomatic CSM and are appropriate surgical candidates.