In Vitro Biomechanical Validation of a Self-Adaptive Ratchet Growing Rod Construct for Fusionless Scoliosis Correction Study Design. In vitro biomechanical evaluation of a novel self-adaptive unidirectional ratchet growing rod (RGR) system. Objective. The aim of this study was to propose and biomechanically validate a novel RGR construct in vitro using porcine thoracic spines and calculate the tensile force required to elongate the RGR with springs, without springs, and with soft tissue encapsulation (induced in vivo in rabbits). Summary of Background Data. Literature lacks clear consensus regarding the implant of choice for early-onset scoliosis. Multiple systems are currently available, and each has its own advantages and disadvantages. Therefore, studying novel designs that can credibly accommodate growth and curb deformity progression is of principle importance. Methods. In vitro biomechanical motion tests were done using six porcine thoracic spines with pedicle screws at T3 and T8. A pure moment of ±5 Nm was loaded in lateral bending (LB) and flexion-extension. Range of motion (ROM) and neutral zone (NZ) of each specimen was determined after connecting the free movable growing rods (FGRs), RGRs, and standard rods (SRs). Tensile tests were done to measure the force required to elongate the RGR with springs, without springs, and with soft tissue encapsulation (induced in vivo in rabbits). Results. Global ROM, implanted T3-T8 ROM, and the NZ of specimens with FGRs and RGRs were significantly higher than that with SRs. The RGRs favored unidirectional elongation in both LB and flexion. The tensile forces required for elongating the RGR without springs, with springs, and with soft tissue capsulation (by a scaled unit of 3 mm) were 3 ± 1.3 N, 10.5 ± 0.4 N, and 48.4 ± 14.4 N, respectively. Conclusion. The RGR could stabilize and favor unidirectional elongation of the implanted spinal column when appropriate forces were present. There was no device failure as far as we have studied and it is anticipated that, with further safety and feasibility assessment, RGRs could be adapted for clinical use. Level of Evidence: N/A

Implant Design and the Anchoring Mechanism Influence the Incidence of Heterotopic Ossification in Cervical Total Disc Replacement at 2-year Follow-up Study Design. A nonrandomized, prospective, and single-center clinical trial. Objective. The aim of this study was to determine whether the prosthesis design, and especially changes in the primary anchoring mechanism between the keel-based ProDisc C and the spike-based ProDisc Vivo, affects the frequency of heterotopic ossification (HO) formation over time. Summary of Background Data. The occurrence of motion-restricting HO as well as underlying risk factors has so far been a widely discussed, but not well understand phenomenon. The anchoring mechanism and the opening of the anterior cortex may be possible causes of this unwanted complication. Methods. Forty consecutive patients treated with the ProDisc C and 42 consecutive patients treated with the ProDisc Vivo were compared with respect to radiological and clinical outcome, with 2 years of follow-up. Clinical outcome scores included the Neck Disability Index (NDI), Visual Analogue Scale (VAS), and arm and neck pain self-assessment questionnaires. Radiological outcomes included the segmental lordosis and range of motion (ROM) of the index-segment as well as the occurrence of HO. Results. The clinical outcome parameters improved in both groups significantly. [ProDisc C: VAS arm and neck pain from 6.3 and 6.2 preoperatively to 0.7 and 1.3; NDI from 23.0 to 3.7; ProDisc Vivo: VAS arm and neck pain from 6.3 and 4.9 to 1.4 and 1.6, NDI from 34.1 to 8.7; 2-year follow-up (FU)]. The ProDisc Vivo cohort demonstrated a significantly lower incidence of HO than the ProDisc C group at 1-year FU (P = 0.0005) and 2-year FU (P = 0.005). Specifically, high-grade HO occurred in 9% versus 31%. Conclusion. These findings demonstrate that prosthesis designs that allow primary anchoring without violation of the cortical surface help to reduce the incidence of severe ossification, possibly affecting the functionality and mobility of the artificial disc device over of time. Level of Evidence: 3

Postoperative Resolution of MR T2 Increased Signal Intensity in Cervical Spondylotic Myelopathy: The Impact of Signal Change Resolution on the Outcomes Study Design. A prospective comparative imaging study. Objective. This study investigated whether postoperative resolution of spinal cord increased signal intensity (ISI) reflected symptom improvement and surgical outcomes in cervical spondylotic myelopathy (CSM) patients. Summary of Background Data. Although some CSM patients exhibit magnetic resonance imaging (MRI) ISI, its alteration and resolution have not been investigated. The association between postoperative ISI resolution and surgical outcomes in CSM patients remains controversial. Methods. A total of 505 consecutive CSM patients (311 males; 194 females) aged a mean of 66.6 years (range, 41–91) were enrolled. All were treated with laminoplasty and underwent MRI scans preoperatively and after an average of 26.5 months postoperatively (range 12–66 months). ISI was classified pre- and postoperatively based on sagittal T2-weighted magnetic resonance images into Grade 0, none; Grade 1, light (obscure); and Grade 2, intense (bright). The patients’ pre- and postoperative neurological statuses were evaluated using the Japanese Orthopedic Association scoring system for cervical myelopathy [Japanese Orthopedic Association (JOA) score] and other quantifiable tests, including the 10-s grip and release (10-s G&R) test and 10-s step test. Results. A total of 337 patients showed preoperative ISI. Among these, 42 (12.5%) showed postoperative ISI resolution, associated with better postoperative JOA score and recovery rate, 10-s G&R and 10-s step test scores than those who retained it. Patients with preoperative Grade 2 ISI had no postoperative ISI resolution. Patients with ISI improvement from Grade 1 to Grade 0 had better outcomes than those with ISI worsening from Grade 1 to Grade 2. Conclusion. Postoperative ISI resolution in CSM patients reflects postoperative symptoms and surgical outcomes. Patients who exhibit ISI resolution have better clinical outcomes. Level of Evidence: 3

Does Disordered Sleep Moderate the Relationship Between Pain, Disability and Downstream Health Care Utilization in Patients With Low Back Pain?: A Longitudinal Cohort From the US Military Health System Study Design. Prospective cohort. Objective. The purpose of this study was to evaluate the influence of disordered sleep on the relationship between pain and health care utilization (HCU) and pain-related disability and HCU in individuals with low back pain (LBP). Summary of Background Data. Disordered sleep and pain influence LBP outcomes, but their relationship with health care seeking after an episode of LBP has not been investigated and could help identify who is at risk for long-term medical care. Methods. This study included patients with LBP participating in a self-management class at a large US military hospital between March 1, 2010 and December 4, 2012. Pain intensity, disability (Oswestry Disability Index), and sleepiness (Epworth Sleepiness Scale) were captured at baseline. Medical visits for a sleep disorder in the 12 months before the class and LBP-related healthcare utilization for the 12 months following the class were abstracted from the Military Health System Data Repository. Separate multivariate analyses evaluating pain intensity and disability as predictors of HCU were developed, with sleepiness and the presence of a sleep disorder as potential moderators. Analyses were adjusted for age, sex, history of back pain, and mental health comorbidities. Results. A total of 757 consecutive participants were included, with 195 (26.8%) diagnosed with a subsequent sleep disorder. Sleepiness was not a significant predictor of HCU. The main effects of disability, pain intensity, and presence of a sleep disorder were significant across all analyses, with higher disability, pain intensity, and presence of a sleep disorder associated with higher predicted visits and costs for LBP. The presence of a sleep disorder was not a significant moderator in any model. Conclusion. Higher pain intensity and disability predicted higher pain-related HCU in the year following a LBP self-management class. The presence of a sleep disorder diagnosis, as recorded in medical records, had a significant independent effect on LBP-related health care visits and costs beyond the influences of pain intensity, disability, and other key demographic and health-related characteristics, but did not moderate these relationships. Level of Evidence: 3

Dual Time-Point 18F-FDG PET/CT in Spinal Sarcoidosis: A Single Institution Case Series Study Design. A case series of dual time-point 18F-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) for the diagnosis of spinal cord sarcoidosis. Objective. The aim of this study was to illustrate three cases of spinal sarcoidosis with occult presentation and subsequent identification with the use of dual time-point 18F-FDG PET/CT. Summary of Background Data. Sarcoidosis of the spinal cord is very rare and when it occurs without systemic manifestations of disease can be a challenging diagnostic dilemma frequently resulting in the need for spinal cord biopsy in order to establish a diagnosis. Methods. Case series presentation and report. Results. This manuscript presents a case series experience of dual time-point 18F-FDG PET/CT for the diagnosis of spinal cord sarcoidosis. We review the cases of three patients who presented with myelopathy and underwent 18F-FDG DTPI as part of the evaluation for enhancing spinal cord lesions of unknown etiology for 2 years at a university-based cancer hospital. 18F-FDG DTPI was vital in making the diagnosis of sarcoidosis, and in two of the cases, the patients were able to avoid biopsy, thereby avoiding potential morbidity from an invasive procedure. Conclusion. 18F-FDG PET/CT imaging is a noninvasive imaging technique that can be crucial in the diagnosis of sarcoidosis of the spinal cord and help avoid unnecessary procedures. Level of Evidence: 4

The Role of Cross-Links in Posterior Spinal Fusion for Cerebral Palsy–Related Scoliosis Study Design. Retrospective review of a multicenter, prospective database. Objective. Our aim was to compare complication rates and maintenance of radiographic correction at 2 years after posterior spinal fusion (PSF) with or without cross-links in patients with cerebral palsy (CP)–related scoliosis. Summary of Background Data. Cross-links are frequently used in PSF to correct scoliosis in patients with CP because they are thought to increase the stiffness and torsional rigidity of the construct. Methods. We reviewed the records of patients with CP who underwent primary PSF with or without cross-links between August 2008 and April 2015. Inclusion criteria were minimum follow-up of 2 years, availability of complications data (implant failure, surgical site infection, revision), and pre- and postoperative measurements of the major curve (measured using the Cobb method). The 256 patients included in this analysis had a mean age of 14.1 ± 2.7 years. Ninety-four patients had cross-links (57% using one cross-link; 43% using two cross-links) and 162 patients did not have cross-links. P < 0.05 was considered statistically significant. Results. The two groups did not differ significantly with regard to sex, age at surgery, preoperative menarche status, Gross Motor Function Classification System level, major curve magnitude, pelvic obliquity, kyphosis, and lordosis angles. There were no significant differences between groups in the correction achieved or the maintenance of correction at 2 years for the major curve, pelvic obliquity, kyphosis, or lordosis (all P > 0.05). Complication rates were similar between the cross-link group (16%, N = 15) and the non–cross-link group (14%, N = 22). Conclusion. At 2 years after PSF to treat CP-related scoliosis, patients had no significant differences in the degree of correction achieved, the maintenance of correction, or the rate of complications between those whose fusion constructs used cross-links and those whose constructs did not. Level of Evidence: 3

Muscle-evoked Potentials After Electrical Stimulation to the Brain in Patients Undergoing Spinal Surgery are Less Affected by Anesthetic Fade With Constant-voltage Stimulation Than With Constant-current Stimulation Study Design. A prospective, within-subject study was conducted. Objective. We aimed to compare the influence of anesthetic fade under maximum stimulation conditions between constant-current and constant-voltage stimulation techniques. Summary of Background Data. The monitoring of muscle-evoked potentials after electrical stimulation to the brain [Br(E)-MSEP)] is useful for assessing the integrity of spinal cord motor tracts during major spine surgery. Nonetheless, Br(E)-MSEP responses are known to deteriorate over the duration of surgeries performed under general anesthesia. This phenomenon is known as anesthetic fade. Methods. We recruited 117 patients undergoing various spinal surgeries from the cervical to the lumbar level. We excluded 29 cases with insufficient data. The decrease rate of the Br(E)-MSEP amplitude for each muscle was examined. Br(E)-MSEP monitoring with constant-current and constant-voltage stimulations at the C3 and C4 electrode positions was applied. Compound muscle action potentials (CMAPs) were bilaterally recorded from the abductor pollicis brevis, deltoid, abductor hallucis, tibialis anterior, gastrocnemius, and quadriceps muscles. We defined the decrease rate as follows: (initial CMAPs-final CMAPs)/initial CMAPs × 100. Differences in the decrease rate were evaluated between stimulators, limbs (upper vs. lower), and operative time group (lowest quartile vs. highest quartile). Results. The overall decrease rate (across all muscles) increased as the operative time increased, and the rate was higher in the lower limbs than in the upper limbs. In addition, the overall decrease rate was lower with constant-voltage stimulation than with constant-current stimulation. Furthermore, the decrease rate for constant-current stimulation was significantly higher than that for constant-voltage stimulation, regardless of the operative time. Conclusion. The CMAP waveform with constant-voltage stimulation is less susceptible to anesthetic fade than that with constant-current stimulation, even during long surgeries. Level of Evidence: 3

Eating Behavior Traits, Weight Loss Attempts, and Vertebral Dimensions Among the General Northern Finnish Population Study Design. A population-based birth cohort study. Objective. To evaluate the associations of eating behavior traits and weight loss attempts with vertebral size among the general Northern Finnish population. Summary of Background Data. Vertebral fragility fractures are a typical manifestation of osteoporosis, and small vertebral dimensions are a well-established risk factor for vertebral fracturing. Previous studies have associated cognitive eating restraint and diet-induced weight loss with deteriorated bone quality at various skeletal sites, but data on vertebral geometry are lacking. Methods. This study of 1338 middle-aged Northern Finns evaluated the associations of eating behavior traits (flexible and rigid cognitive restraint of eating, uncontrolled eating, emotional eating; assessed by the Three-Factor Eating Questionnaire-18) and weight loss attempts (assessed by a separate questionnaire item) with magnetic resonance imaging-derived vertebral cross-sectional area (CSA). Sex-stratified linear regression models were used to analyze the data, taking body mass index, leisure-time physical activity, general diet, smoking, and socioeconomic status as potential confounders. Results. Women with rigid or rigid-and-flexible cognitive eating restraints had 3.2% to 3.4% smaller vertebral CSA than those with no cognitive restraint (P ≤ 0.05). Similarly, the women who reported multiple weight loss attempts in adulthood and midlife had 3.5% smaller vertebral size than those who did not (P = 0.03). Other consistent findings were not obtained from either sex. Conclusion. Rigid cognitive eating restraint and multiple weight loss attempts predict small vertebral size and thus decreased spinal health among middle-aged women, but not among men. Future longitudinal studies should confirm these findings. Level of Evidence: 3

Cost-effectiveness of Operative versus Nonoperative Treatment of Adult Symptomatic Lumbar Scoliosis an Intent-to-treat Analysis at 5-year Follow-up Study Design. Secondary analysis using data from the NIH-sponsored study on adult symptomatic lumbar scoliosis (ASLS) that included randomized and observational arms. Objective. The aim of this study was to perform an intent-to-treat cost-effectiveness study comparing operative (Op) versus nonoperative (NonOp) care for ASLS. Summary of Background Data. The appropriate treatment approach for ASLS continues to be ill-defined. NonOp care has not been shown to improve outcomes. Surgical treatment has been shown to improve outcomes, but is costly with high revision rates. Methods. Patients with at least 5-year follow-up data were included. Data collected every 3 months included use of NonOp modalities, medications, and employment status. Costs for index and revision surgeries and NonOp modalities were determined using Medicare Allowable rates. Medication costs were determined using the RedBook and indirect costs were calculated based on reported employment status and income. Qualityadjusted life year (QALY) was determined using the SF6D. Results. There were 81 of 95 cases in the Op and 81 of 95 in the NonOp group with complete 5-year follow-up data. Not all patients were eligible 5-year follow-up at the time of the analysis. All patients in the Op and 24 (30%) in the NonOp group had surgery by 5 years. At 5 years, the cumulative cost for Op was $96,000 with a QALY gain of 2.44 and for NonOp the cumulative cost was $49,546 with a QALY gain of 0.75 with an incremental cost-effectiveness ratio (ICER) of $27,480 per QALY gain. Conclusion. In an intent-to-treat analysis, neither treatment was dominant, as the greater gains in QALY in the surgery group come at a greater cost. The ICER for Op compared to NonOp treatment was above the threshold generally considered cost-effective in the first 3 years of the study but improved over time and was highly cost-effective at 4 and 5 years. Level of Evidence: 2