Faculty Bibliography

BACKGROUND/AIMS: Surgical techniques for effective high-grade spondylolisthesis (HGS) remain controversial. This study aims to evaluate radiographic/clinical outcomes in HGS patients treated using modified "Reverse Bohlman" (RB) technique. METHODS: Review of consecutive HGS patients undergoing RB at a single university-center from 2006 to 2013. Clinical, surgical, radiographic parameters collected. RESULTS: Six patients identified: five with L5-S1 HGS with L4-L5 instability and one had an L4-5 isthmic spondylolisthesis and grade 1 L5-S1 isthmic spondylolisthesis. Two interbody graft failures and one L5-S1 pseudoarthrosis. Postoperative improvement of anterolisthesis (62.3% vs. 49.6%, p = 0.003), slip angle (10 vs. 5 degrees , p = 0.005), and lumbar lordosis (49 vs. 57.5 degrees , p = 0.049). CONCLUSIONS: RB technique for HGS recommended when addressing adjacent level instability/slip.

OBJECTIVES: The purpose of this study was to determine the cost/quality-adjusted life-year (QALY) of the operative treatment of lumbar spondylolisthesis and identify factors associated with cost-effectiveness at 2 years. METHODS: We evaluated patients who underwent surgery for spondylolisthesis. The QALY was determined from the EQ5D. Outcomes were also assessed using the Oswestry Disability Index (ODI). Surgical, neuromonitoring, and anesthesia Current Procedural Terminology (CPT) codes as well as hospital Diagnosis-Related Group codes were used to determine the Medicare direct care costs of surgery. Indirect costs were modeled based on existing literature. A discounting rate of 3% was applied. Analysis was performed to determine which factors were associated with a cost/QALY less than $100,000. RESULTS: There were 44 patients who underwent surgery for either degenerative (30) or isthmic spondylolisthesis (14). There were 27 women and 17 men, with an average age at surgery of 59.7 years (standard deviation [SD] = 14.69) and an average follow-up of 2 years (SD = 0.82). The average postoperative improvement in ODI was 24.77 (SD = 23.9), and change in QALY was 0.43 (SD = 0.30). The average cost/QALY at 2 years for direct care costs was $89,065. The average cost/QALY at 2 years for direct plus indirect costs was $112,588. Higher preoperative leg pain and greater leg pain change was associated with a cost/QALY <$100,000 (p < .005, p < .028). The cost-effective group had a higher proportion of patients with disease extent of two or more levels (p = .021). When comparing surgical techniques of anterior-posterior and posterior only, there was no difference in cost-effectiveness. CONCLUSIONS: Spondylolisthesis surgery is cost-effective at 2 years, with a QALY change of 0.43 and a direct cost/QALY of $89,065. Higher preoperative leg pain and larger extent of disease was associated with cost-effectiveness. LEVEL OF EVIDENCE: IV.

INTRODUCTION: Wound infections following spinal surgery place a high toll on both the patient and the healthcare system. Although several large series studies have examined the incidence and distribution of spinal wound infection, the applicability of these studies varies greatly since nearly every study is either retrospective and/or lacks standard inclusion criteria for defining surgical site infection. To address this void, we present results from prospectively gathered thoracolumbar spine surgery data for which the Centers for Disease Control (CDC) criteria were stringently applied to define a surgical site infection (SSI). METHODS: A prospective randomized trial of 314 patients who underwent multilevel thoracolumbar spinal surgery with instrumentation followed by postoperative drain placement was completed (Takemoto et al., 2015). The trial consisted of two antibiotic arms: one for 24-hours, and the other for the duration of the drain; no differences were found between the arms. All infections meeting CDC criteria for SSI were included. RESULTS: A total of 40 infections met CDC criteria for SSI, for an overall incidence of 12.7%. Of these, 20 (50%) were culture-positive. The most common organism was Staphylococcus aureus (4 total: methicillin-sensitive=2; methicillin-resistant=2), followed by coagulase-negative Staphylococcus (3 cases), Propionibacterium acnes and Escherichia coli (2 cases each). Six infections grew multiple organisms, most commonly involving coagulase-negative staphylococcus and enterococcus. CONCLUSIONS: Our findings indicate that thoracolumbar SSI occurs at the higher end of the range cited in the literature (2-13%), which is largely based on retrospective data not subjected to the inclusivity of SSI as defined by the CDC. The three most common organisms in our analysis (S. aureus, P. acnes, E. coli) are consistent with previous reports. Staphylococcus aureus continues to be the most common causative organism and continued vigilance and searching for preventive measures need to be a high priority. This study provides Level I evidence.

BACKGROUND CONTEXT: Numerous studies have demonstrated poorer outcomes in patients with Workers' Compensation (WC) when compared to those without WC following treatment of various of health conditions including spine disorders. It is thus important to consider compensation status when assessing treatment outcomes in spine surgery. However, reported strengths of association have varied significantly (1.31-7.22). PURPOSE: The objective of this study was to evaluate the association of unsatisfactory outcomes on compensation status in spine surgery patients. STUDY DESIGN/SETTING: Meta-analysis PATIENT SAMPLE: Not applicable OUTCOME MEASURE: Demographics, type of surgery, country, follow-up time, patient satisfaction, return to work and non-union events. METHODS: Both prospective and retrospective studies that compared outcomes between compensated and non-compensated patients in spine surgery were included. Two independent investigators extracted outcome data. The meta-analysis was performed using Revman software. Random effects model was used to calculate risk ratio (RR, 95% confidence interval (CI) for dichotomous variables. There are no conflicts of interest to report among the authors, and no funding was received for this study. RESULTS: 31 studies (13 prospective; 18 retrospective) with a total of 3567 patients were included in the analysis. Follow-up time varied from 4 months to 10 years. 12 studies involved only decompression; the rest were fusion. Overall RR of an unsatisfactory outcome was 2.12 [1.74, 2.58; p<0.001] in patients with WC when compared to those without WC after surgery. RR of an unsatisfactory outcome in patients with WC, compared to those without, was 2.09 [1.38, 3.17]; p<0.01 among studies from Europe and Australia and 2.14 [1.48, 2.60]; p<0.01 among US studies. RR of decompression-only procedures was 2.53 [1.85, 3.47]; p<0.01 and 1.79 [1.45, 2.21]; p<0.01 for fusion. 43% (209/491) of patients with WC returned to work versus 17% (214/1250) of those without WC (RR 2.07 [1.43, 2.98]; p<0.001). 25 % (74/292) and 13.5% (39/287) of patients had non-union in the compensated and non-compensated groups, respectively. This was not statistically significant (RR 1.33 [0.92, 1.91]; p=0.07). CONCLUSIONS: Workers' compensation patients have a two-fold increased risk of an unsatisfactory outcome compared to non-compensated patients after surgery. This association was consistent when studies were grouped by country or procedure. Compensation status must be considered in all surgical intervention studies.

BACKGROUND: In patients with single-level cervical degenerative disc disease, total disc arthroplasty can relieve radicular pain and preserve functional motion between two vertebrae. We compared the efficacy and safety of cervical total disc arthroplasty with that of anterior cervical discectomy and fusion (ACDF) for the treatment of single-level cervical degenerative disc disease between C3-C4 and C6-C7. METHODS: Two hundred and nine patients at thirteen sites were randomly treated with either total disc arthroplasty with ProDisc-C (n = 103) or with ACDF (n = 106). Patients were assessed preoperatively; at six weeks and three, six, twelve, eighteen, and twenty-four months postoperatively; and then annually until seven years postoperatively. Outcome measures included the Neck Disability Index (NDI), the Short Form-36 (SF-36), postoperative neurologic parameters, secondary surgical procedures, adverse events, neck and arm pain, and satisfaction scores. RESULTS: At seven years, the overall follow-up rate was 92% (152 of 165). There were no significant differences in demographic factors, follow-up rate, or patient-reported outcomes between groups. Both procedures were effective in reducing neck and arm pain and improving and maintaining function and health-related quality of life. Neurologic status was improved or maintained in 88% and 89% of the patients in the ProDisc-C and ACDF groups, respectively. After seven years of follow-up, thirty secondary surgical procedures had been performed in nineteen (18%) of 106 patients in the ACDF group compared with seven secondary surgical procedures in seven (7%) of 103 patients in the ProDisc-C group (p = 0.0099). There were no significant differences in the rates of any device-related adverse events between the groups. CONCLUSIONS: Total disc arthroplasty with ProDisc-C is a safe and effective surgical treatment of single-level symptomatic cervical degenerative disc disease. Clinical outcomes after total disc arthroplasty with ProDisc-C were similar to those after ACDF. Patients treated with ProDisc-C had a lower probability of subsequent surgery, suggesting that total disc arthroplasty provides durable results and has the potential to slow the rate of adjacent-level disease. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND CONTEXT: In transforminal lumbar interbody fusion (TLIF), bilateral pedicle screw/rod fixation has been shown to increase fusion construct stability and decrease posterior instrumentation stress when compared to unilateral instrumentation. However, unilateral instrumentation is beneficial over bilateral instrumentation due to shorter operative time, less blood loss and reduced implant costs. It is important to note though that comparative studies between unilateral and bilateral instrumentation in TLIF have shown similar patient satisfaction outcomes, they are limited in their evaluation of complications due to small sample size of studies. PURPOSE: The purpose of this meta-analysis was to evaluate complications, and fusion rates between unilateral and bilateral instrumentation in TLIF. STUDY DESIGN/SETTING: Meta-analysis of randomized controlled trials. PATIENT SAMPLE: 549 patients undergoing one- and multi-levels TLIF. OUTCOME MEASURES: Outcome data extracted included fusion rates, health related quality of life (HRQoL) scores and complications including cage migration, dural tear, deep vein thrombosis, surgical site infections and screw failures. METHODS: Randomized controlled trials (RCTs) that compared outcomes between unilateral and bilateral pedicle screw instrumentation in single- and multi-level TLIF were identified. Data extraction was performed by two independent reviewers. Meta-analysis was performed using RevMan 5. Weighted standardized mean difference (SMD) and odds ratio (OR) 95% confidence intervals (CI) were calculated. Jadad scoring was used to assess bias of included studies. RESULTS: Eight RCTs were included, having a total of 549 patients (267 unilateral/282 bilateral). Minimum follow-up ranged from 3 to 24 months. Bias-assessment scores varied between 0 and 3 indicating high-moderate bias-risk. Six involved open TLIF procedures and two involved minimally invasive TLIF. There was no difference between postoperative Health Related Quality of Life scores in the unilateral and bilateral instrumented groups (SMD = 0.29; [-0.77, 0.18]; p=0.69). There was no statistical difference in fusion rates (OR = 0.47; 95% CI [0.21, 1.04], p=0.68), with 88.9% and 95.0% achieving fusion in the unilateral and bilateral groups, respectively. The unilateral cohort had a higher incidence of cage migration (5.6%) when compared to the bilateral cohort (2.5%), approaching statically significant (p=0.07). Other complications which included dural tears, deep vein thrombosis, surgical site infections and screw failures were comparable between the groups. CONCLUSIONS: Fusion rates and complications appear comparable in unilateral and bilateral instrumentation in TLIF. Though not statistically significant, there was higher incidence of cage migration in the unilateral cohort

BACKGROUND CONTEXT: Numerous studies have demonstrated poorer outcomes in patients receiving Workers' Compensation following treatment of various health conditions including spine disorders. It is thus important to consider compensation status when assessing treatment outcomes in spine surgery. However, reported strengths of association have varied significantly (1.31-7.22). PURPOSE: The objective of this study was to evaluate the association of unsatisfactory outcomes on compensation status in spine surgery patients. STUDY DESIGN/SETTING: Meta-analysis. PATIENT SAMPLE: 3567 patients undergoing spine surgery. OUTCOME MEASURES: Demographics, type of surgery, country, follow-up time, patient satisfaction, return to work and non-union events. METHODS: Both prospective and retrospective studies that compared outcomes between compensated and non-compensated patients in spine surgery were included. Outcome data extracted by two independent investigators. The meta-analysis was performed using Revman software. Depending on heterogeneity, a fixed or random effects model was used to calculate risk ratio (RR, 95% confidence interval [CI]) for dichotomous variables. RESULTS: 31 studies (13 prospective; 18 retrospective) with a total of 3,567 patients were included in the analysis. Follow-up time varied from 4 months to 10 years. Twelve studies involved only decompression; the rest were fusion. Overall RR of an unsatisfactory outcome was 2.12 [1.74, 2.58; p<0.001] in compensated patients when compared to noncompensated patients after surgery. RR of an unsatisfactory outcome in compensated patients compared to noncompensated was 2.09 [1.38, 3.17]; p< 0.01 among studies from Europe and Australia and 2.14 [1.48, 2.60]; p< 0.01 among US studies. RR of decompression-only procedures was 2.53 [1.85, 3.47] and 1.79 [1.45, 2.21] for fusion. 52% (182/491) of compensated patients returned to work versus 82% (1034/1250) of non-compensated (RR 0.73 [0.59, 0.90]; p<0.001). 25 % (74/292) and 13.5% (39/ 287) of patients had nonunion in the compensated and noncompensated groups, respectively. This was not statistically significant (RR 1.33 [0.92, 1.91]; p=0.07). CONCLUSIONS: Workers' Compensation patients have a two-fold increased risk of an unsatisfactory outcome compared to noncompensated patients after surgery. This association was consistent when studies were grouped by country or procedure. Compensation status must be considered in all surgical intervention studies

BACKGROUND CONTEXT: Development of symptomatic adjacent level degeneration (ALD) following anterior cervical discectomy and fusion (ACDF) remains a clinical concern. Cervical artificial disc replacement (C-ADR) maintains motion at the surgical level, and has been demonstrated to lower the incidence of developing radiographic ALD (R-ALD) than following ACDF. PURPOSE: To compare the rates of progressive R-ALD 7 years postsurgery in patients treated with ProDisc-C (DePuy Synthes Spine, Raynham, MA) C-ADR or ACDF for one-level symptomatic cervical disc disease, and to examine the effect of final flexion-extension range of motion (ROM) of the C-ADR with the progression of RALD. STUDY DESIGN/SETTING: A prospective randomized FDA approved IDE study was conducted at 13 sites to assess the safety and effectiveness of single-level C-ADR compared to ACDF. The study included annual patient follow-up through 7 years. PATIENT SAMPLE: 209 patients were randomized and treated (106 ACDF; 103 C-ADR). OUTCOME MEASURES: All radiographs were assessed by independent radiologists utilizing a qualitative assessment of disc degeneration at adjacent levels based on the Kellgren-Lawrence system (0-4 scale). Range of motion at the index and adjacent levels were measured. METHODS: Radiographic results are presented for patients at final 7-year follow-up using the last observation carried forward with a minimum 5- year follow up. Progression in R-ALD, and ROM at the C-ADR, at the latest follow-up was assessed. RESULTS: Final follow-up data was available for 156 patients (86 C-ADR, 70 ACDF). Basic demographics were similar between the two patient groups. The rate of progressive R-ALD at either adjacent level (worse case) was statistically significantly lower in the C-ADR cohort compared to ACDF patients (rates: 53% vs 77% respectively (p=0.011). The rate of R-ALD was significantly lower only in the superior adjacent level for the C-ADR vs ACDF patients (36% vs 59%, p=0.0022), although R-ALD trended lower in C-ADR patients for the inferior adjacent level (C-ADR 34% vs ACDF 43% [p=0.21]). The ROM of the C-ADR at final follow up was found to significant correlate (inversely) with the rate of progressive R-ALD. Discs moving 0-3degree had a 68% rate of progressive R-ALD, while the rate was only 53% in discs moving 4-6degree, and only 43% in discs moving 7degree or more (p=0.0113). Severe progression of R-ALD (grade 0-1 initially, 3-4 at follow-up) in C-ADR patients was found in 45% of patients with discs moving 0-3degree, in no patients with discs moving 4-6degree, and in 9.5% of patients with discs moving 7+degree (p=0.002). CONCLUSIONS: Long term results demonstrated that the rate of progressive radiographic adjacent level disc degeneration was significantly lower in C-ADR patients as compared to ACDF patients. The rate of radiographic ALD in the C-ADR patients was found to correlate inversely with the final ROM of the C-ADR

BACKGROUND: Wound drains that are left in place for a prolonged period of time have a higher rate of bacterial contamination. Following spinal surgery, a drain is often left in place for a longer period of time if it maintains a high output. Given the major consequences of an infection following spinal surgery and the lack of data with regard to the use of antibiotics and drains, we performed a study of patients with a drain following spinal surgery to compare infection rates between those who were treated with antibiotics for twenty-four hours and those who received antibiotics for the duration for which the drain was in place. METHODS: We performed a prospective randomized trial of 314 patients who underwent multilevel thoracolumbar spinal surgery followed by use of a postoperative drain. The patients were randomized into two groups, one of which received perioperative antibiotics for twenty-four hours (twenty-four-hour group) and the other of which received antibiotics for the duration that the drain was in place (drain-duration group). Data collected included demographic characteristics, medical comorbidities, type of spinal surgery, and surgical site infection. RESULTS: Twenty-one (12.4%) of the 170 patients in the twenty-four-hour group and nineteen (13.2%) of the 144 in the drain-duration group developed a surgical site infection (p = 0.48). There were no significant differences between the twenty-four-hour and drain-duration groups with respect to demographic characteristics (except for the American Society of Anesthesiologists [ASA] classification), operative time, type of surgery, drain output, or length of hospital stay. CONCLUSIONS: Continuing perioperative administration of antibiotics for the entire duration that a drain is in place after spinal surgery did not decrease the rate of surgical site infections. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.