Kris E. Radcliff

Association of myelopathy scores with cervical sagittal balance and normalized spinal cord volume: analysis of 56 preoperative cases from the AOSpine North America Myelopathy study.

Study Design. Post hoc analysis of prospectively collected data. Objective. Development of methods to determine in vivo spinal cord dimensions and application to correlate preoperative alignment, myelopathy, and health-related quality-of-life scores in patients with cervical spondylotic myelopathy (CSM). Summary of Background Data. CSM is the leading cause of spinal cord dysfunction. The association between cervical alignment, sagittal balance, and myelopathy has not been well characterized. Methods. This was a post hoc analysis of the prospective, multicenter AOSpine North America CSM study. Inclusion criteria for this study required preoperative cervical magnetic resonance imaging (MRI) and neutral sagittal cervical radiography. Techniques for MRI assessment of spinal cord dimensions were developed. Correlations between imaging and health-related quality-of-life scores were assessed. Results. Fifty-six patients met inclusion criteria (mean age = 55.4 yr). The modified Japanese Orthopedic Association (mJOA) scores correlated with C2–C7 sagittal vertical axis (SVA) (r = −0.282, P = 0.035). Spinal cord volume correlated with cord length (r = 0.472, P < 0.001) and cord average cross-sectional area (r = 0.957, P < 0.001). For all patients, no correlations were found between MRI measurements of spinal cord length, volume, mean cross-sectional area or surface area, and outcomes. For patients with cervical lordosis, mJOA scores correlated positively with cord volume (r = 0.366, P = 0.022), external cord area (r = 0.399, P = 0.012), and mean cross-sectional cord area (r = 0.345, P = 0.031). In contrast, for patients with cervical kyphosis, mJOA scores correlated negatively with cord volume (r = −0.496, P = 0.043) and mean cross-sectional cord area (r = −0.535, P = 0.027). Conclusion. This study is the first to correlate cervical sagittal balance (C2–C7 SVA) to myelopathy severity. We found a moderate negative correlation in kyphotic patients of cord volume and cross-sectional area to mJOA scores. The opposite (positive correlation) was found for lordotic patients, suggesting a relationship of cord volume to myelopathy that differs on the basis of sagittal alignment. It is interesting to note that sagittal balance but not kyphosis is tied to myelopathy score. Future work will correlate alignment changes to cord morphology changes and myelopathy outcomes. Summary Statements. This is the first study to correlate sagittal balance (C2–C7 SVA) to myelopathy severity. We found a moderate negative correlation in kyphotic patients of cord volume and cross-sectional area to mJOA scores. The opposite (positive correlation) was found for lordotic patients, suggesting a relationship of cord volume to myelopathy that differs on the basis of sagittal alignment.

Epidural steroid injections are associated with less improvement in patients with lumbar spinal stenosis: a subgroup analysis of the Spine Patient Outcomes Research Trial.

Study Design. Subgroup analysis of prospective, randomized database from the Spine Patient Outcomes Research Trial (SPORT) Objective. The hypothesis of this study was that patients who received ESI during initial treatment as part of SPORT (The Spine Patient Outcomes Research Trial) would have improved clinical outcome and a lower rate of crossover to surgery than patients who did not receive ESI. Summary of Background Data. The use of epidural steroid injection (ESI) in patients with lumbar spinal stenosis is common, although there is little evidence in the literature to demonstrate its long-term benefi t in the treatment of lumbar stenosis. Methods. Patients with lumbar spinal stenosis who received ESI within the first 3 months of enrollment in SPORT (ESI) were compared with patients who did not receive epidural injections during the first 3 months of the study (no-ESI). Results. There were 69 ESI patients and 207 no-ESI patients. There were no significant differences in demographic factors, baseline clinical outcome scores, or operative details between the groups, although there was a significant increase in baseline preference for nonsurgical treatment among ESI patients (ESI 62% vs. no-ESI 33%, P < 0.001). There was an average 26-minute increase in operative time and an increased length of stay by 0.9 days among the ESI patients who ultimately underwent surgical treatment. Averaged over 4 years, there was significantly less improvement in 36-Item Short Form Health Survey (SF-36) Physical Function among surgically treated ESI patients (ESI 14.8 vs. no-ESI 22.5, P = 0.025). In addition, there was significantly less improvement among the nonsurgically treated patients in SF-36 Body Pain (ESI 7.3 vs. no-ESI 16.7, P = 0.007) and SF-36 Physical Function (ESI 5.5 vs. no-ESI 15.2, P = 0.009). Of the patients assigned to the surgical treatment group, there was a significantly increased crossover to nonsurgical treatment among patients who received an ESI (ESI 33% vs. no-ESI 11%, P = 0.012). Of the patients assigned to the nonoperative treatment group, there was a significantly increased crossover to surgical treatment in the ESI patients (ESI 58% vs. no-ESI 32%, P = 0.003). Conclusion. Despite equivalent baseline status, ESIs were associated with significantly less improvement at 4 years among all patients with spinal stenosis in SPORT. Furthermore, ESIs were associated with longer duration of surgery and longer hospital stay. There was no improvement in outcome with ESI whether patients were treated surgically or nonsurgically.

Risk for adjacent segment and same segment reoperation after surgery for lumbar stenosis: a subgroup analysis of the Spine Patient Outcomes Research Trial (SPORT).

Study Design. Subgroup analysis of a prospective, randomized database. Summary of Background Data. Reoperation due to recurrence of index level pathology or adjacent segment disease is a common clinical problem. Despite multiple studies on the incidence of reoperation, there have been few comparative studies establishing risk factors for reoperation after spinal stenosis surgery. The hypothesis of this subgroup analysis was that lumbar fusion or particular patient characteristics, such as obesity, would render patients with lumbar stenosis more susceptible to reoperation at the index or adjacent levels. Methods. The study population combined the randomized and observational cohorts enrolled in Spine Patient Outcomes Research Trial for treatment of spinal stenosis. The surgically treated patients were stratified according to those who had reoperation (n = 54) or no reoperation (n = 359). Outcome measures were assessed at baseline, 1 year, 2 years, 3 years, and 4 years. The difference in improvement between those who had reoperation and those who did not was determined at each follow-up period. Results. Of the 413 patients who underwent surgical treatment of spinal stenosis, 54 (13%) underwent a reoperation within 4 years. At baseline, there were no significant differences in demographic characteristics or clinical outcome scores between reoperation and nonreoperation groups. Furthermore, between groups there were no differences in the severity of symptoms, obesity, physical examination signs, levels of stenosis, location of stenosis, stenosis severity, levels of fusion, levels of laminectomy, levels decompressed, operation time, and intraoperative or postoperative complications. There was an increased percentage of patients with duration of symptoms greater than 12 months in the reoperation group (56% reoperation vs. 36% no reoperation, P < 0.008). At final follow-up, there was significantly less improvement in the outcome of the reoperation group in MOS 36-item Short-Form Health Survey physical function (14.4 vs. 22.6, P < 0.05), Oswestry Disability Index (−12.4 vs. −21.1, P < 0.01), and Sciatica Bothersomeness Index (−5 vs. −8.1, P < 0.006). Conclusion. Lumbar fusion and instrumentation were not associated with increased rate of reoperation at index or adjacent levels compared with nonfusion techniques. The only specific risk factor for reoperation after treatment of spinal stenosis was duration of pretreatment symptoms more than 12 months. The overall incidence of reoperations for spinal stenosis surgery was 13%, and reoperations were equally distributed between index and adjacent lumbar levels. Reoperation may be related to the natural history of spinal degenerative disease.

Five-year clinical results of cervical total disc replacement compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled, multicenter investigational device exemption clinical trial.

OBJECTIVE The purpose of this study was to report the outcome of a study of 2-level cervical total disc replacement (Mobi-C) versus anterior cervical discectomy and fusion (ACDF). Although the long-term outcome of single-level disc replacement has been extensively described, there have not been previous reports of the 5-year outcome of 2-level cervical disc replacement. METHODS This study reports the 5-year results of a prospective, randomized US FDA investigational device exemption (IDE) study conducted at 24 centers in patients with 2-level, contiguous, cervical spondylosis. Clinical outcomes at up to 60 months were evaluated, including validated outcome measures, incidence of reoperation, and adverse events. The complete study data and methodology were critically reviewed by 3 independent surgeon authors without affiliation with the IDE study or financial or institutional bias toward the study sponsor. RESULTS A total of 225 patients received the Mobi-C cervical total disc replacement device and 105 patients received ACDF. The Mobi-C and ACDF follow-up rates were 90.7% and 86.7%, respectively (p = 0.39), at 60 months. There was significant improvement in all outcome scores relative to baseline at all time points. The Mobi-C patients had significantly more improvement than ACDF patients in terms of Neck Disability Index score, SF-12 Physical Component Summary, and overall satisfaction with treatment at 60 months. The reoperation rate was significantly lower with Mobi-C (4%) versus ACDF (16%). There were no significant differences in the adverse event rate between groups. CONCLUSIONS Both cervical total disc replacement and ACDF significantly improved general and disease-specific measures compared with baseline. However, there was significantly greater improvement in general and disease-specific outcome measures and a lower rate of reoperation in the 2-level disc replacement patients versus ACDF control patients. Clinical trial registration no. NCT00389597 ( clinicaltrials.gov ).

Patients With Uncontrolled Components of Metabolic Syndrome Have Increased Risk of Complications Following Total Joint Arthroplasty

Metabolic syndrome (MetS)-a diagnostic grouping of diabetes, dyslipidemia, hypertension, and obesity-has been indicated as a risk factor for perioperative complications following total joint arthroplasty (TJA). This study investigates the impact of MetS on perioperative complications, specifically the importance of controlling MetS components. One hundred thirty-three patients undergoing TJA with all four components of MetS were identified. They were matched one-to-one with patients without MetS. Control of diabetes, dyslipidemia, and hypertension was assessed. Thirty-five patients with MetS were found to have at least a single uncontrolled component. The complication rates were 49%, 8%, and 8% for uncontrolled MetS, controlled MetS, and no MetS, respectively. Multivariate analysis confirmed independent associations between control of MetS components and both perioperative complications and length of stay. Both surgeons and patients should be aware of the substantial risk of dangerous complications following TJA in patients with uncontrolled metabolic syndrome.

Thromboelastography Predictive of Death in Trauma Patients

To determine if thromboelastography (TEG) is predictive of patient outcomes following traumatic injury.

Preoperative delay of more than 1 hour increases the risk of surgical site infection.

Study Design. Retrospective institutional database review. Objective. To determine whether preoperative in-room time is a risk factor for surgical site infection (SSI). Summary of Background Data. Prior to spine surgery, while the patient is in the operating room, several procedures may be performed that may delay surgery. During this time, the sterile field may be exposed and may become contaminated. The hypothesis of this study was that the length of time in the operative room prior to surgical incision (anesthesia ready time [ART]) was related to the risk of SSI. Methods. From 2005 to 2009, we identified 276 patients who developed SSI out of 7991 cases that underwent spine surgery from 2005 to 2009. Patient demographic factors, American Society of Anesthesiologists score, wound classification, number of levels, anatomic region, type of surgical approach, and length of surgery were extrapolated. ART was calculated as the time after the patient was brought into the operating room prior to surgical incision. Multivariate analysis was performed to identify risk factors for SSI. Results. Mean ART was significantly (P = 0.001) higher in patients with infection (68 min) compared with those without infection (60 min). The infection rate was higher in cases with ART more than 1 hour compared with those with less than 1 hour (4.9% vs. 2.3%, P = 0.001). In multivariate analysis, ART more than 1 hour was an independent risk factor for SSI, along with number of levels, American Society of Anesthesiologists score and posterior approach. The highest percentage of cases with ART more than 1 hour occurred in August and September. Conclusion. Preoperative in-room time prior to the start of surgical incision is an independent risk factor for SSI. All possible steps should be taken prior to entry into the operating theater to reduce in-room time and opening of surgical sterile instrumentation be delayed until the surgery is ready to proceed. Level of Evidence: 3

Intrawound Vancomycin Decreases the Risk of Surgical Site Infection After Posterior Spine Surgery: A Multicenter Analysis

Study Design. Secondary analysis of data from a prospective multicenter observational study. Objective. The aim of this study was to evaluate the occurrence of surgical site infection (SSI) in patients with and without intrawound vancomycin application controlling for confounding factors associated with higher SSI after elective spine surgery. Summary of Background Data. SSI is a morbid and expensive complication associated with spine surgery. The application of intrawound vancomycin is rapidly emerging as a solution to reduce SSI following spine surgery. The impact of intrawound vancomycin has not been systematically studied in a well-designed multicenter study. Methods. Patients undergoing elective spine surgery over a period of 4 years at seven spine surgery centers across the United States were included in the study. Patients were dichotomized on the basis of whether intrawound vancomycin was applied. Outcomes were occurrence of SSI within postoperative 30 days and SSI that required return to the operating room (OR). Multivariable random-effect log-binomial regression analyses were conducted to determine the relative risk of having an SSI and an SSI with return to OR. Results. . A total of 2056 patients were included in the analysis. Intrawound vancomycin was utilized in 47% (n = 966) of patients. The prevalence of SSI was higher in patients with no vancomycin use (5.1%) than those with use of intrawound vancomycin (2.2%). The risk of SSI was higher in patients in whom intrawound vancomycin was not used (relative risk (RR) -2.5, P < 0.001), increased number of levels exposed (RR -1.1, P = 0.01), and those admitted postoperatively to intensive care unit (ICU) (RR -2.1, P = 0.005). Patients in whom intrawound vancomycin was not used (RR -5.9, P < 0.001), increased number of levels were exposed (RR-1.1, P = 0.001), and postoperative ICU admission (RR -3.3, P < 0.001) were significant risk factors for SSI requiring a return to the OR. Conclusion. The intrawound application of vancomycin after posterior approach spine surgery was associated with a reduced risk of SSI and return to OR associated with SSI. Level of Evidence: 2

Bone substitutes and expanders in Spine Surgery: A review of their fusion efficacies

Study Design A narrative review of literature. Objective This manuscript intends to provide a review of clinically relevant bone substitutes and bone expanders for spinal surgery in terms of efficacy and associated clinical outcomes, as reported in contemporary spine literature. Summary of Background Data Ever since the introduction of allograft as a substitute for autologous bone in spinal surgery, a sea of literature has surfaced, evaluating both established and newly emerging fusion alternatives. An understanding of the available fusion options and an organized evidence-based approach to their use in spine surgery is essential for achieving optimal results. Methods A Medline search of English language literature published through March 2016 discussing bone graft substitutes and fusion extenders was performed. All clinical studies reporting radiological and/or patient outcomes following the use of bone substitutes were reviewed under the broad categories of Allografts, Demineralized Bone Matrices (DBM), Ceramics, Bone Morphogenic proteins (BMPs), Autologous growth factors (AGFs), Stem cell products and Synthetic Peptides. These were further grouped depending on their application in lumbar and cervical spine surgeries, deformity correction or other miscellaneous procedures viz. trauma, infection or tumors; wherever data was forthcoming. Studies in animal populations and experimental in vitro studies were excluded. Primary endpoints were radiological fusion rates and successful clinical outcomes. Results A total of 181 clinical studies were found suitable to be included in the review. More than a third of the published articles (62 studies, 34.25%) focused on BMP. Ceramics (40 studies) and Allografts (39 studies) were the other two highly published groups of bone substitutes. Highest radiographic fusion rates were observed with BMPs, followed by allograft and DBM. There were no significant differences in the reported clinical outcomes across all classes of bone substitutes. Conclusions There is a clear publication bias in the literature, mostly favoring BMP. Based on the available data, BMP is however associated with the highest radiographic fusion rate. Allograft is also very well corroborated in the literature. The use of DBM as a bone expander to augment autograft is supported, especially in the lumbar spine. Ceramics are also utilized as bone graft extenders and results are generally supportive, although limited. The use of autologous growth factors is not substantiated at this time. Cell matrix or stem cell-based products and the synthetic peptides have inadequate data. More comparative studies are needed to evaluate the efficacy of bone graft substitutes overall.

Seven-year cost-effectiveness of ProDisc-C total disc replacement: results from investigational device exemption and post-approval studies.

OBJECTIVE The purpose of this study was to evaluate the 7-year cost-effectiveness of cervical total disc replacement (CTDR) versus anterior cervical discectomy and fusion (ACDF) for the treatment of patients with single-level symptomatic degenerative disc disease. A change in the spending trajectory for spine care is to be achieved, in part, through the selection of interventions that have been proven effective yet cost less than other options. This analysis complements and builds upon findings from other cost-effectiveness evaluations of CTDR through the use of long-term, patient-level data from a randomized study. METHODS This was a 7-year health economic evaluation comparing CTDR versus ACDF from the US commercial payer perspective. Prospectively collected health care resource utilization and treatment effects (quality-adjusted life years [QALYs]) were obtained from individual patient-level adverse event reports and SF-36 data, respectively, from the randomized, multicenter ProDisc-C total disc replacement investigational device exemption (IDE) study and post-approval study. Statistical distributions for unit costs were derived from a commercial claims database and applied using Monte Carlo simulation. Patient-level costs and effects were modeled via multivariate probabilistic analysis. Confidence intervals for 7-year costs, effects, and net monetary benefit (NMB) were obtained using the nonparametric percentile method from results of 10,000 bootstrap simulations. The robustness of results was assessed through scenario analysis and within a parametric regression model controlling for baseline variables. RESULTS Seven-year follow-up data were available for more than 70% of the 209 randomized patients. In the base-case analysis, CTDR resulted in mean per-patient cost savings of