Evaluation of "appropriate use criteria" for surgical decision-making in lumbar degenerative spondylolisthesis. A controlled, multicentre, prospective observational study.

INTRODUCTION: Selecting patients with lumbar degenerative spondylolisthesis (LDS) for surgery is difficult. Appropriate use criteria (AUC) have been developed to clarify the indications for LDS surgery but have not been evaluated in controlled studies. METHODS: This prospective, controlled, multicentre study involved 908 patients (561 surgical and 347 non-surgical controls; 69.5 ± 9.7y; 69% female), treated as per normal clinical practice. Their appropriateness for surgery was afterwards determined using the AUC. They completed the Core Outcome Measures Index (COMI) at baseline and 12 months' follow-up. Multiple regression adjusting for confounders evaluated the influence of appropriateness designation and treatment received on the 12-month COMI and achievement of MCIC (≥ 2.2-point-reduction). RESULTS: As per convention, appropriate (A) and uncertain (U) groups were combined for comparison with the inappropriate (I) group. For the adjusted 12-month COMI, the benefit of surgery relative to non-surgical care was not significantly greater for the A/U than the I group (p = 0.189). There was, however, a greater treatment effect of surgery for those with higher baseline COMI (p = 0.035). The groups' adjusted probabilities of achieving MCIC were: 83% (A/U, receiving surgery), 71% (I, receiving surgery), 50% (A/U, receiving non-surgical care), and 32% (I, receiving non-surgical care). CONCLUSIONS: A/U patients receiving surgery had the highest chances of achieving MCIC, but the AUC were not able to identify which patients had a greater treatment effect of surgery relative to non-surgical care. The identification of other characteristics that predict a greater treatment effect of surgery, in addition to baseline COMI, is required to improve decision-making.

Transmission-Based Vertebrae Strength Probe Development: Far Field Probe Property Extraction and Integrated Machine Vision Distance Validation Experiments.

We are developing a transmission-based probe for point-of-care assessment of vertebrae strength needed for fabricating the instrumentation used in supporting the spinal column during spinal fusion surgery. The device is based on a transmission probe whereby thin coaxial probes are inserted into the small canals through the pedicles and into the vertebrae, and a broad band signal is transmitted from one probe to the other across the bone tissue. Simultaneously, a machine vision scheme has been developed to measure the separation distance between the probe tips while they are inserted into the vertebrae. The latter technique includes a small camera mounted to the handle of one probe and associated fiducials printed on the other. Machine vision techniques make it possible to track the location of the fiducial-based probe tip and compare it to the fixed coordinate location of the camera-based probe tip. The combination of the two methods allows for straightforward calculation of tissue characteristics by exploiting the antenna far field approximation. Validation tests of the two concepts are presented as a precursor to clinical prototype development.

Core outcome domains for clinical trials in non-specific low back pain.

PURPOSE: Inconsistent reporting of outcomes in clinical trials of patients with non-specific low back pain (NSLBP) hinders comparison of findings and the reliability of systematic reviews. A core outcome set (COS) can address this issue as it defines a minimum set of outcomes that should be reported in all clinical trials. In 1998, Deyo et al. recommended a standardized set of outcomes for LBP clinical research. The aim of this study was to update these recommendations by determining which outcome domains should be included in a COS for clinical trials in NSLBP. METHODS: An International Steering Committee established the methodology to develop this COS. The OMERACT Filter 2.0 framework was used to draw a list of potential core domains that were presented in a Delphi study. Researchers, care providers and patients were invited to participate in three Delphi rounds and were asked to judge which domains were core. A priori criteria for consensus were established before each round and were analysed together with arguments provided by panellists on importance, overlap, aggregation and/or addition of potential core domains. The Steering Committee discussed the final results and made final decisions. RESULTS: A set of 280 experts was invited to participate in the Delphi; response rates in the three rounds were 52, 50 and 45%. Of 41 potential core domains presented in the first round, 13 had sufficient support to be presented for rating in the third round. Overall consensus was reached for the inclusion of three domains in this COS: 'physical functioning', 'pain intensity' and 'health-related quality of life'. Consensus on 'physical functioning' and 'pain intensity' was consistent across all stakeholders, 'health-related quality of life' was not supported by the patients, and all the other domains were not supported by two or more groups of stakeholders. Weighting all possible argumentations, the Steering Committee decided to include in the COS the three domains that reached overall consensus and the domain 'number of deaths'. CONCLUSIONS: The following outcome domains were included in this updated COS: 'physical functioning', 'pain intensity', 'health-related quality of life' and 'number of deaths'. The next step for the development of this COS will be to determine which measurement instruments best measure these domains.

Evaluation of the Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system as a guide to surgical technique selection.

BACKGROUND CONTEXT: The role of fusion in degenerative spondylolisthesis (DS) is controversial. The Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) classification system was developed to assist surgeons in surgical technique selection based on individual patient characteristics. This system has not been clinically validated as a guide to surgical technique selection. PURPOSE: The purpose of this study was to determine if outcomes vary with different surgical techniques across the CARDS categories. STUDY DESIGN/SETTING: Prospective cohort study performed at one Swiss and one American spine center. PATIENT SAMPLE: Five hundred eight patients with DS undergoing surgical treatment. OUTCOME MEASURES: Core Outcomes Measure Index (COMI) at 3 months and 12 months postoperatively. METHODS: Patients undergoing surgery for DS were enrolled at 2 institutions and classified according to the CARDS system using dynamic radiographs. The Core Outcome Measure Index (COMI) was completed preoperatively, and 3 and 12 months postoperatively. Surgical technique was classified as uninstrumented (decompression alone or decompression with uninstrumented fusion) or instrumented (decompression with pedicle screw instrumentation with or without interbody fusion). Unadjusted analyses and mixed effect models compared COMI scores between the two surgery technique groups (uninstrumented vs instrumented), stratified by CARDS category over time. Reoperation rates were also compared between the surgery technique groups stratified by CARDS category. Partial funding was given through NASS grant for clinical research. RESULTS: Five hundred five out of 508 patients enrolled in the study had sufficient data to be classified according to CARDS. Seven percent were classified as CARDS A, 28% as CARDS B, 48% as CARDS C, and 17% as CARDS D (CARDS A most "stable," CARDS D least "stable"). One hundred and thirty-three patients (26%) underwent decompression alone, 30 (6%) underwent decompression and uninstrumented fusion, 42 (8%) underwent decompression and posterolateral instrumented fusion, and 303 (60%) underwent decompression with posterolateral and interbody instrumented fusion. Patients in the least "stable" categories tended to be less likely to be treated with an uninstrumented technique (CARDS D 19% vs 32% for the other categories, p=.10). There were no significant differences in 3 or 12-month COMI scores between surgical technique groups stratified by CARDS category in the unadjusted or adjusted analyses. In the unadjusted analyses, there was a trend towards less improvement in 12-month COMI change score in the CARDS D patients in the uninstrumented group compared to the instrumented group (-2.7 vs -4.1, p=.10). Reoperation rates were not significantly different between the surgical technique groups stratified by CARDS category. CONCLUSIONS: In general, outcomes for uninstrumented and instrumented surgical techniques were similar across the CARDS categories. Surgeons likely took factors included in CARDS into account during surgical technique selection. This resulted in a low number of CARDS D (n=15) patients being treated with uninstrumented techniques, which limited the statistical power of this analysis. As such, this study does not validate CARDS as a useful classification system for surgical technique selection in DS.

Patient-Reported Allergies, a Marker of Preoperative Pain and Disability in Elective Spine Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: Previous literature demonstrates mixed results regarding the relationship between patient-reported allergies and pain, function, and satisfaction scores. The objective of this study was to investigate the correlation between patient-reported allergies and preoperative Oswestry Disability Index (ODI), Neck Disability Index (NDI), and Patient-Reported Outcomes Measurement System (PROMIS) scores. METHODS: All patients undergoing elective cervical, lumbar procedures between May 2017 and October 2018 were included. Baseline demographic information was recorded, as well as all reported allergies or adverse reactions. Preoperative PROMIS, ODI, and NDI scores were recorded. Hierarchical multiple linear regressions were used to assess the relationship between total number of allergies and the preoperative pain and function scores. RESULTS: A total of 570 patients were included (476 lumbar, 94 cervical). The mean number of allergies reported was 1.89 ± 2.32. The mean preoperative ODI and NDI scores were 46.39 ± 17.67 and 43.47 ± 16.51, respectively. The mean preoperative PROMIS Physical Health and PROMIS Mental Health scores were 37.21 ± 6.54 and 43.89 ± 9.26, respectively. Hierarchical multiple linear regression showed that total number of reported allergies shared a statistically significant negative relationship with all of the following scores: ODI (B = 0.83, P = .02), NDI (B = 1.45, P = .02), PROMIS Physical Health (B = -0.29, P = .013), and PROMIS Mental Health (B = -0.38, P = .024). CONCLUSIONS: Patient-reported allergies share a statistically significant negative relationship with preoperative pain and function scores; as patients have increasing total number of allergies, the ODI/NDI scores become worse (increase) and the PROMIS scores become worse (decrease).

Keys to diagnosis and management of spinal epidural abscesses: 9 years of institutional experience.

OBJECTIVE: Spinal epidural abscesses (SEA's) are a challenge to diagnose, particularly if there are non-contiguous (skip) lesions. There is also limited data to predict which patients can be treated with antibiotics alone and which require surgery. We sought to assess which demographics, clinical and laboratory findings can guide both diagnosis and management of SEA's. METHODS: All patients with SEA (ICD9 324.1, ICD10 G06.1) between April 2011-May 2019 at a single tertiary center were included. A retrospective EMR review was completed. Patient and disease characteristics were compared using appropriate statistical tests. RESULTS: 108 patients underwent initial surgical treatment versus 105 that were treated medically initially; 22 (21 %) of those failed medical management. Patients who failed medical management had significantly higher CRP, longer symptom duration, and had higher rates of concurrent non-spinal infections. 9% of patients had skip lesions. Patients with skip lesions had significantly higher WBC, ESR, as well as higher rates of bacteremia and concurrent non-spinal infections. Demographic characteristics and proportion with IVDU, smoking, malignancy, and immunosuppression were similar among the three treatment groups. CONCLUSIONS: 21 % of SEA patients failed initial medical management; they had significantly greater CRP, longer symptom duration, more commonly had neurologic deficits, and concurrent non-spinal infections. 9% of patients had skip lesions; they had significantly higher WBC, ESR, rates of bacteremia and infections outside the spine. These variables may guide diagnostic imaging, and identify those at risk of failing of medical management, and therefore require more involved clinical evaluation, and consideration for surgical intervention.

Percutaneous Doxycycline Foam Injections: Novel Treatment Method for Vertebral Aneurysmal Bone Cysts.

Aneurysmal bone cysts (ABCs) are among the most aggressive benign bone tumors, often occurring in both long bones and the spine. Treatment remains controversial as recurrence rates continue to be high. Treatment options include curettage with or without bone grafting, arterial embolization, en block resection with or without instrumentation or arthrodesis, radiation, and intralesional drug injections (steroids, calcitonin, doxycycline). We present the case of a patient with a thoracic vertebral ABC who underwent 2 rounds of doxycycline foam percutaneous injections. At the 1-year follow up appointment, all symptoms had been resolved. Repeat computed tomography and magnetic resonance imaging demonstrated that the ABC had nearly filled in completely with new bone. Our case demonstrates successful use of this percutaneous, less invasive method in the management of vertebral ABCs.

A 5-Year Review of Hospital Costs and Reimbursement in the Surgical Management of Degenerative Spondylolisthesis.

BACKGROUND: To evaluate charges, expenses, reimbursement, and hospital margins with noninstrumented posterolateral fusion in situ (PLF), posterolateral fusion with pedicle screws (PPS), and PPS with interbody device (PLIF) in degenerative spondylolisthesis with spinal stenosis. METHODS: A retrospective chart review was performed from 2010 to 2014 based on ICD-9 diagnoses of degenerative spondylolisthesis with spinal stenosis in patients undergoing single-level fusions. All charges, expenses, reimbursement, and margins were obtained through financial auditing. A multivariate linear regression model was used to compare demographics, charges, etc. A 1-way analysis of variance with Tukey post hoc analysis was used to analyze reimbursements and margins based upon insurances. RESULTS: Two hundred thirty-three patients met inclusion criteria. The overall charges and expenses for PLF were significantly less compared to both types of instrumented fusions (P < .0001). Medicare and private insurance were the most common insurance types; Medicare and private insurance mean reimbursements for PLF were $36,903 and $47,086, respectively; for PPS, $37,450 and $53,851, and for PLIF $40,171 and $51,640. Hospital margins for PPS and PLIF in Medicaid patients were negative (-$3,702 and -$6,456). Hospital margins were largest for both worker's compensation and private insurance patients in all fusion groups. Hospital margins with Medicare for PLF, PPS, and PLIF were $24,347, $19,205, and $23,046, respectively. Hospital margins for private insurance for PLF, PPS, and PLIF were $37,569, $36,834, and $33,134, respectively. CONCLUSIONS: As more instrumentation is used, the more it costs both the hospital and the insurance companies; hospital margins did not increase correspondingly. CLINICAL RELEVANCE: Improved understanding of related costs and margins associated with lumbar fusions to help transition to more cost effective spine centers.

Reducing Radiation and Lowering Costs With a Standardized Care Pathway for Nonoperative Thoracolumbar Fractures.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: There is marked variation in the management of nonoperative thoracolumbar (TL) compression and burst fractures. This was a quality improvement study designed to establish a standardized care pathway for TL fractures treated with bracing, and to then evaluate differences in radiographs, length of stay (LOS), and cost before and after the pathway. METHODS: A standardized pathway was established for management of nonoperative TL burst and compression fractures (AOSpine classification type A1-A4 fractures). Bracing, radiographs, costs, complications, and LOS before and after pathway adoption were analyzed. Differences between the neurosurgery and orthopedic spine services were compared. RESULTS: Between 2012 and 2015, 406 nonoperative burst and compression TL fractures were identified. A total of 183 (45.1%) were braced, 60.6% with a custom-made thoracolumbosacral orthosis (TLSO) and 39.4% with an off-the-shelf TLSO. The number of radiographs significantly reduced after initiation of the pathway (3.23 vs 2.63, P = .010). A total of 98.6% of braces were custom-made before the pathway; 69.6% were off-the-shelf after the pathway. The total cost for braced patients after pathway adoption decreased from $10 462.36 to $8928.58 (P = .078). Brace-associated costs were significantly less for off-the-shelf TSLO versus custom TLSO ($1352.41 vs $3719.53, respectively, P < .001). The mean LOS and complication rate did not change significantly following pathway adoption. The orthopedic spine service braced less frequently than the neurosurgery service (40.7% vs 52.2%, P = .023). CONCLUSIONS: Standardized care pathways can reduce cost and radiation exposure without increasing complication rates in nonoperative management of thoracolumbar compression and burst fractures.

Core outcome measurement instruments for clinical trials in nonspecific low back pain.

To standardize outcome reporting in clinical trials of patients with nonspecific low back pain, an international multidisciplinary panel recommended physical functioning, pain intensity, and health-related quality of life (HRQoL) as core outcome domains. Given the lack of a consensus on measurement instruments for these 3 domains in patients with low back pain, this study aimed to generate such consensus. The measurement properties of 17 patient-reported outcome measures for physical functioning, 3 for pain intensity, and 5 for HRQoL were appraised in 3 systematic reviews following the COSMIN methodology. Researchers, clinicians, and patients (n = 207) were invited in a 2-round Delphi survey to generate consensus (≥67% agreement among participants) on which instruments to endorse. Response rates were 44% and 41%, respectively. In round 1, consensus was achieved on the Oswestry Disability Index version 2.1a for physical functioning (78% agreement) and the Numeric Rating Scale (NRS) for pain intensity (75% agreement). No consensus was achieved on any HRQoL instrument, although the Short Form 12 (SF12) approached the consensus threshold (64% agreement). In round 2, a consensus was reached on an NRS version with a 1-week recall period (96% agreement). Various participants requested 1 free-to-use instrument per domain. Considering all issues together, recommendations on core instruments were formulated: Oswestry Disability Index version 2.1a or 24-item Roland-Morris Disability Questionnaire for physical functioning, NRS for pain intensity, and SF12 or 10-item PROMIS Global Health form for HRQoL. Further studies need to fill the evidence gaps on the measurement properties of these and other instruments.

Reoperation for Recurrent Intervertebral Disc Herniation in the Spine Patient Outcomes Research Trial: Analysis of Rate, Risk Factors, and Outcome.

STUDY DESIGN: This study was a post-hoc subgroup analysis of prospectively collected data in the Spine Patient Outcomes Research Trial (SPORT). OBJECTIVE: The aim of this study was to determine the risk factors for and to compare the outcomes of patients undergoing revision disc excision surgery in SPORT. SUMMARY OF BACKGROUND DATA: Risk factors for reherniation and outcomes after revision surgery have not been well-studied. This information is critical for proper patient counseling and decision-making. METHODS: Patients who underwent primary discectomy in the SPORT intervertebral disc herniation cohort were analyzed to determine risk factors for undergoing revision surgery. Risk factors for undergoing revision surgery for reherniation were evaluated using univariate and multivariate analysis. Primary outcome measures consisted of Oswestry Disability Index (ODI), the Sciatica Bothersomeness index (SBI), and the Short Form 36 (SF-36) at 6 weeks, 3 months, 6 months, and yearly to 4 years. RESULTS: Of 810 surgical patients, 74 (9.1%) received revision surgery for reherniation. Risk factors for reherniation included: younger age (hazard ratio [HR] 0.96 [0.94-0.99]), lack of a sensory deficit (HR 0.61 [0.37-0.99]) lack of motor deficit (HR 0.54 [0.32-0.91]), and higher baseline ODI score (HR 1.02 [1.01-1.03]). The time-adjusted mean improvement from baseline to 4 years was less for the reherniation group on all outcome measures (Bodily Pain Index [BP] 39.5 vs. 44.9, P = 0.001; Physical Function Index [PF] 37.1 vs. 44.5, P < 0.001; ODI 33.9 vs. 38.3, P < 0.001; SBI 8.7 vs. 10.5, P < 0.001). At 4 years, only SBI (-9 vs. -11.4, P = 0.002) was significantly lower in the reherniation group. CONCLUSION: Younger patients with higher baseline disability without neurological deficit are at increased risk of undergoing revision surgery for reherniation. Those considering revision surgery for reherniation will likely improve significantly following surgery, but possibly not as much as with primary discectomy. LEVEL OF EVIDENCE: 3.

Pain Recurrence After Discectomy for Symptomatic Lumbar Disc Herniation.

STUDY DESIGN: Secondary analysis of data from a concurrent randomized trial and cohort study. OBJECTIVE: The aim of this study was to determine risks and predictors of recurrent pain following standard open discectomy for subacute/chronic symptomatic lumbar disc herniation (SLDH). SUMMARY OF BACKGROUND DATA: Most previous studies of recurrence after discectomy do not explicitly define pain resolution and recurrence, and do not account for variable durations of time at risk for recurrence. METHODS: We used survival analysis methods to examine predictors of leg pain recurrence. For individuals with initial resolution of leg pain, we defined recurrent leg pain as having leg pain, receiving lumbar epidural steroid injections, or undergoing lumbar surgery subsequent to initial leg pain resolution. We calculated cumulative risks of leg pain recurrence using Kaplan-Meier survival curves, and examined predictors of recurrence using Cox proportional hazards models. We used similar methods to examine LBP recurrence. RESULTS: One- and three-year cumulative risks of leg pain recurrence were 20% and 45%, respectively. One- and three- year leg pain recurrence risks were substantially lower in participants with complete initial resolution of leg pain (17% and 41%, respectively) than in those without (27% and 54%, respectively). In multivariate analyses, complete leg pain resolution (adjusted hazard ratio [aHR] 0.69; 95% confidence interval [CI] 0.52-0.90), smoking (aHR 1.68 [95% CI 1.22-2.33]), and depression (aHR 1.74 [95% CI 1.18-2.56]) predicted leg pain recurrence. The 1- and 3-year risk of LBP recurrence was 29% and 65%, respectively. LBP recurrence risk at 3 years was substantially lower in participants with complete initial resolution of LBP than in those without, but not at 1 year. CONCLUSION: Recurrence of leg pain and LBP is common after discectomy for SLDH. Cumulative risks of both leg pain and LBP recurrence were generally lower in participants achieving complete initial resolution of pain post-discectomy. LEVEL OF EVIDENCE: 2.

C2 Vertebral Fractures in the Medicare Population: Incidence, Outcomes, and Costs.

BACKGROUND: Cervical 2 (C2) fractures in the elderly are common, and the incidence of these fractures has been increasing. Surgical and nonoperative treatments are associated with high complication and mortality rates, and these rates have not been evaluated at the population level, to our knowledge. The purpose of this study was to use the Medicare claims database to determine trends in treatment, surgical and nonoperative outcomes, and Medicare reimbursement for treatment of these fractures. METHODS: We examined the Medicare claims database from 2000 to 2011 to identify patients admitted for the treatment of a C2 fracture. The incidence of fractures and the rates of nonoperative and surgical treatment were determined across the study period. We compared rates of mortality and life-threatening complications between patients treated nonoperatively and surgically. Centers for Medicare & Medicaid Services (CMS) payments for the initial admission as well as for subsequent inpatient admissions during the ninety-day post-admission period were compared between treatment groups. We used multivariate analysis to control for differences in patient characteristics between groups. RESULTS: There were 81,596 admissions for C2 fracture identified, and 53,338 met inclusion criteria. The incidence of C2 fractures increased 135% from 2000 to 2011, but the rate of surgical treatment remained constant at 16%. There was significantly lower mortality at thirty days for the surgical group at 8.3% compared with the nonoperative group at 16.2% (p < 0.001) and at one year for the surgical group at 21.7% compared with the nonoperative group at 32.3% (p < 0.001). Life-threatening complications within thirty days of admission were slightly more common in the surgical group at 10.9% compared with the nonoperative group at 9.0% (p < 0.05). Medicare reimbursements for the initial inpatient admission were significantly higher (p < 0.001) in U.S. dollars for the surgical group at $21,487 compared with the nonoperative group at $8469, and this significant difference (p < 0.001) persisted in the ninety-day post-discharge period at $10,487 for the surgical group compared with $8410 for the nonoperative group. CONCLUSIONS: Although the incidence of C2 fractures in the Medicare population increased from 2000 to 2011, the rate of surgery stayed relatively constant. After controlling for baseline differences, patients treated with surgery had significantly lower thirty-day and one-year mortality rates compared with patients treated nonoperatively. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cost Effectiveness of Operative Versus Non-Operative Treatment of Geriatric Type-II Odontoid Fracture.

STUDY DESIGN: Cost-effectiveness analysis. OBJECTIVE: To examine the cost-effectiveness of operative versus non-operative treatment of type-II odontoid fractures in patients older than 64 years old. SUMMARY OF BACKGROUND DATA: Significant controversy exists regarding the optimum treatment of geriatric patients with type-II odontoid fractures. Operative treatment leads to lower rates of non-union but carries surgical risks. Non-operative treatment does not carry surgical risks but has higher non-union rates. METHODS: A decision-analytic model was created to compare operative and non-operative treatment of type-II odontoid fractures among three age cohorts (65-74, 75-84, >84) based on expected costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs; cost per QALY gained). Age-specific mortality rates for both treatments, costs for treatment, and complication rates were taken from the literature, and data from 2010 US life tables were used for age-specific life expectancy. Costs of complications were estimated using data obtained at a level-I trauma center using micro-costing. Sensitivity analyses of all model parameters were conducted. RESULTS: Among the 65- to 74-year-old cohort, operative treatment was more costly ($53,407 vs. $30,553) and more effective (12.00 vs. 10.11 QALY), with an ICER of $12,078/QALY. Among the 75- to 84-year-old cohort, operative treatment was more costly ($51,308 vs. $29,789) and more effective (6.85 vs. 6.31 QALY), with an ICER of $40,467/QALY. Among the over-84 cohort, operative treatment was dominated by non-operative treatment as it was both more costly ($45,978 vs. $28,872) and less effective (2.48 vs. 3.73 QALY). The model was robust to sensitivity analysis across reasonable ranges for utility of union, disutility of complications and delayed surgery, and probabilities of non-union and complications. CONCLUSION: Operative treatment is cost-effective in patients age 65 to 84 when using $100,000/QALY as a benchmark but less effective and more costly than non-operative treatment in patients older than 84 years. LEVEL OF EVIDENCE: 2.

Recurrence of Pain After Usual Nonoperative Care for Symptomatic Lumbar Disk Herniation: Analysis of Data From the Spine Patient Outcomes Research Trial.

OBJECTIVE: To determine risks and predictors of recurrent leg and low back pain (LBP) after unstructured, usual nonoperative care for subacute/chronic symptomatic lumbar disk herniation (LDH). DESIGN: Secondary analysis of data from a concurrent randomized trial and observational cohort study. SETTING: Thirteen outpatient spine practices. PARTICIPANTS: A total of 199 participants with resolution of leg pain and 142 participants with resolution of LBP from among 478 participants receiving usual nonoperative care for symptomatic LDH. ASSESSMENT OF RISK FACTORS: Potential predictors of recurrence included time to initial symptom resolution, sociodemographics, clinical characteristics, work-related factors, imaging-detected herniation characteristics, and baseline pain bothersomeness. MAIN OUTCOME MEASUREMENTS: Leg pain and LBP bothersomeness were assessed by the use of a 0-6 numerical scale at up to 4 years of follow-up. For individuals with initial resolution of leg pain, we defined recurrent leg pain as having leg pain, receiving lumbar epidural steroid injections, or undergoing lumbar surgery subsequent to initial leg pain resolution. We calculated cumulative risks of recurrence by using Kaplan-Meier survival plots and examined predictors of recurrence using Cox proportional hazards models. We used similar definitions for LBP recurrence. RESULTS: One- and 3-year cumulative recurrence risks were 23% and 51% for leg pain, and 28% and 70% for LBP, respectively. Early leg pain resolution did not predict future leg pain recurrence. Complete leg pain resolution (adjusted hazard ratio [aHR] 0.47, 95% confidence interval [CI] 0.31-0.72) and posterolateral herniation location (aHR 0.61; 95% CI 0.39-0.97) predicted a lower risk of leg pain recurrence, and joint problems (aHR 1.89; 95% CI 1.16-3.05) and smoking (aHR 1.81; 95% CI 1.07-3.05) predicted a greater risk of leg pain recurrence. For participants with complete initial resolution of pain, recurrence risks at 1 and 3 years were 16% and 41% for leg pain and 24% and 59% for LBP, respectively. CONCLUSIONS: Recurrence of pain is common after unstructured, usual nonsurgical care for LDH. These risk estimates depend on the specific definitions applied, and the predictors identified require replication in future studies.

Intervertebral neck injury criterion for simulated frontal impacts.

OBJECTIVE: The Intervertebral Neck Injury Criterion (IV-NIC) is based on the hypothesis that dynamic intervertebral motion beyond physiological limits may injure soft tissues. In contrast, the Neck Injury Criterion (NIC) hypothesizes that sudden change in spinal fluid pressure may cause neural injuries. The goals of this study, using the biofidelic whole human cervical spine model with muscle force replication, were to determine the IV-NIC injury threshold due to frontal impact at each intervertebral level, and to compare the IV-NIC and NIC in determining injury. METHODS: Using a bench-top apparatus, frontal impacts were simulated at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. Pre- and post-trauma flexibility testing measured the soft tissue injury; that is, a significant increase (p < 0.05) in neutral zone or range of motion at any intervertebral level, above the corresponding physiological limit. RESULTS: Results indicated that the soft tissue injury occurred due to flexion mode of injury and its threshold was 8 g. The average IV-NIC injury threshold (95% confidence interval) was 2.0 (1.2-2.8) at C4-C5 and 2.3 (1.6-3.0) at C6-C7, while the average NIC injury threshold was 18.4 (17.9-19.0) m(2)/s(2). The NIC injury threshold was reached significantly earlier than all the IV-NIC injury thresholds, demonstrating that the NIC may be unable to predict facet and soft tissue injury caused by non-physiologic inververtebral rotation. CONCLUSIONS: Present results suggest that IV-NIC is an effective tool for determining soft tissue neck injuries by identifying the intervertebral level, mode, time, and severity of injury.

Modeling 1-year survival after surgery on the metastatic spine.

BACKGROUND CONTEXT: Choosing appropriate surgical patients in the setting of spinal metastases can be challenging. Existing scoring systems focus primarily on patient selection or operative techniques. These scores are limited in their capacity to predict postoperative survival. PURPOSE: The aim was to model survival after spine surgery for metastastic disease. STUDY DESIGN: This was a retrospective multicenter study. PATIENT SAMPLE: All patients who had undergone surgery for the treatment of metastatic spinal disease at one of four tertiary care centers between 2007 and 2013 were included. OUTCOME MEASURE: The outcome measure was 1-year survival after surgery. METHODS: Demographic, medical, oncologic, surgical, and survival data were abstracted from medical records. The effect of predictor variables on survival was evaluated alone and in combination using stepwise logistic regression. Multivariable logistic regression was subsequently used to adjust for confounders. A predictive score was then developed and compared against that of the modified Bauer score alone in terms of prognosticating 1-year survival after surgery. RESULTS: In the time period under investigation, 318 patients underwent surgical intervention for metastastic disease involving the spine, with 307 having data available for analysis. The survival rate at 1 year was 48% (n=142), with a median survival of 10 months. In final adjusted analysis, preoperative modified Bauer score (odds ratio [OR] 3.00; 95% confidence interval [CI] 1.80-5.01; p<.001), ambulatory status (OR 2.47; 95% CI 1.48-4.14; p=.001), and serum albumin (OR 2.80; 95% CI 1.66-4.72; p<.001) were all independent predictors of 1-year survival. The most parsimonious model weighted the modified Bauer score with 2 points and intact ambulatory status and normal serum albumin level with 1 point each, with a ceiling score of 3. The final model using the predictive score was able to explain 74% of the variation in 1-year survival. In contrast, the modified Bauer score alone was only able to explain 64% of the variation in 1-year survival. CONCLUSIONS: This study demonstrates the importance of including factors related to the overall health of a patient, in addition to parameters surrounding their cancer diagnosis, to better prognosticate survival. Our predictive score performed better than the modified Bauer alone and may be used to predict survival after surgical intervention for metastatic disease. LEVEL OF EVIDENCE: III.

Cervical spine curvature during simulated whiplash.

OBJECTIVE: To develop a new method to describe cervical spine curvature and evaluate the potential for injury in the upper and lower cervical spine during simulated whiplash. DESIGN: A method was developed to integrate the upper and lower cervical spine rotations and describe the spine curvature. BACKGROUND: In vivo and in vitro whiplash simulations have documented the development of an S-shape curvature with simultaneous upper cervical spine flexion and lower cervical spine extension immediately following rear-impact. Investigators have hypothesized that the injury potential is highest during the S-shape phase. However, little data exist on the spine curvature during whiplash and its relation to spine injury. METHODS: A biofidelic model and a bench-top whiplash apparatus were used in an incremental rear-impact protocol (maximum 8 g) to simulate whiplash of increasing severity. To describe the spine curvature, the upper and lower cervical spine rotations were normalized to corresponding physiological limits. RESULTS: Average peak lower cervical spine extension first exceeded the physiological limits (P<0.05) at a horizontal T1 acceleration of 5 g. Average peak upper cervical spine extension exceeded the physiological limit at 8 g, while peak upper cervical spine flexion never exceeded the physiological limit. In the S-shape phase, lower cervical spine extension reached 84% of peak extension during whiplash. CONCLUSIONS: Both the upper and lower cervical spine are at risk for extension injury during rear-impact. Flexion injury is unlikely.