Postoperative C5 Palsy after Anterior or Posterior Decompression for Degenerative Cervical Myelopathy: A Subgroup Analysis of the Multicenter, Prospective, Randomized, Phase III, CSM-Protect Clinical Trial.

STUDY DESIGN: Retrospective cohort study of prospectively accrued data. OBJECTIVE: To evaluate a large, prospective, multicentre dataset of surgically-treated DCM cases on the contemporary risk of C5 palsy with surgical approach. SUMMARY OF BACKGROUND DATA: The influence of surgical technique on postoperative C5 palsy after decompression for degenerative cervical myelopathy (DCM) is intensely debated. Comprehensive analyses are needed using contemporary data and accounting for covariates. METHODS: Patients with moderate to severe DCM were prospectively enrolled in the multicenter, randomized CSM-Protect clinical trial and underwent either anterior or posterior decompression between Jan 31, 2012, to May 16, 2017. The primary outcome was the incidence of postoperative C5 palsy, defined as onset of muscle weakness by at least one grade in manual muscle test at the C5 myotome with slight or absent sensory disruption after cervical surgery. Two comparative cohorts were made based on anterior or posterior surgical approach. Multivariate hierarchical mixed-effects logistic regression was used to estimate odds ratios (OR) with 95% confidence intervals (CI) for C5 palsy. RESULTS: A total of 283 patients were included, and 53.4% underwent posterior decompression. The total incidence of postoperative C5 palsy was 7.4% and was significantly higher in patients that underwent posterior decompression compared to anterior decompression (11.26% vs. 3.03%, P=0.008). After multivariable regression, posterior approach was independently associated with greater than four times the likelihood of postoperative C5 palsy (P=0.017). Rates of C5 palsy recovery were comparable between the two surgical approaches. CONCLUSION: The odds of postoperative C5 palsy are significantly higher after posterior decompression compared to anterior decompression for DCM. This may influence surgical decision-making when there is equipoise in deciding between anterior and posterior treatment options for DCM. LEVEL OF EVIDENCE: Therapeutic Level II.

Laminoplasty versus laminectomy with fusion for treating multilevel degenerative cervical myelopathy.

Background: Laminectomy with fusion (LF) and laminoplasty (LP) are common posterior decompression procedures used to treat multilevel degenerative cervical myelopathy (DCM). There is debate on their relative efficacy and safety for treatment of DCM. The goal of this study is to examine outcomes and costs of LF and LP procedures for DCM. Methods: This is a retrospective review of adult patients (<18) at a single center who underwent elective LP and LF of at least 3 levels from C3-C7. Outcome measures included operative characteristics, inpatient mobility status, length of stay, complications, revision surgery, VAS neck pain scores, and changes in radiographic alignment. Oral opioid analgesic needs and hospital cost comparison were also assessed. Results: LP cohort (n=76) and LF cohort (n=59) reported no difference in neck pain at baseline, 1, 6, 12, and 24 months postoperatively (p>.05). Patients were successfully weaned off opioids at similar rates (LF: 88%, LP: 86%). Fixed and variable costs respectively with LF cases hospital were higher, 15.7% and 25.7% compared to LP cases (p=.03 and p<.001). LF has a longer length of stay (4.2 vs. 3.1 days, p=.001). Wound-related complications were 5 times more likely after LF (13.6% vs. 5.9%, RR: 5.15) and C5 palsy rates were similar across the groups (LF: 11.9% LP: 5.6% RR: 1.8). Ground-level falls requiring an emergency department visit were more likely after LF (11.9% vs. 2.6%, p=.04). Conclusions: When treating multilevel DCM, LP has similar rates of new or increasing axial neck pain compared to LF. LF was associated with greater hospital costs, length of stay, and complications compared to LP. LP may in fact be a less morbid and more cost-effective alternative to LF for patients without cervical deformity.

Intraoperative neuromonitoring in spine surgery: large database analysis of cost-effectiveness.

Background: Given the increased attention to functional improvement in spine surgery as it relates to activities of daily living and cost, it is critical to fully understand the health care economic impact of enabling technologies. The use of intraoperative neuromonitoring (IOM) during spine surgery has long been controversial. Questions pertaining to utility, medico-legal considerations, and cost-effectiveness continue to be unresolved. The purpose of this study is to determine the cost-effectiveness by assessing quality-of-life due to adverse events averted, decreased postoperative pain, decreased revision rates, and improved patient reported outcomes (PROs). Methods: The study patient population was extracted from a large multicenter database collected by a single, national IOM provider. Over 50,000 patient charts were abstracted and included in this analysis. The analysis was conducted in accordance with the second panel on cost-effectiveness health and medicine. Health-related utility was derived from questionnaire answers and expressed in quality-adjusted life years (QALYs). Both cost and QALY outcomes were discounted at a yearly rate of 3% to reflect their present value. Cost-effectiveness was calculated as the incremental cost-effectiveness ratio (ICER) for IOM. A value under the commonly accepted United States-based willingness-to-pay (WTP) threshold of $100,000 per QALY was considered cost-effective. Scenario (including litigation), probabilistic (PSA), and threshold sensitivity analyses were conducted to determine model discrimination and calibration. Results: The primary time horizon used to estimate cost and health utility was 2-years following index surgery. On average, index surgery for patients with IOM costs are approximately $1,547 greater than non-IOM cases. The base case assumed an inpatient Medicare population however multiple outpatient and payer scenarios were assessed in the sensitivity analysis. From a health system perspective IOM is cost-effective, yielding better utilities but at a higher cost than the non-IOM strategy (ICER $60,734 per QALY). From a societal perspective the IOM strategy was dominant, suggesting that better outcomes were achieved at less cost. Except for an entirely privately insured population, alternative scenarios such as, outpatient and a 50:50 Medicare/privately insured population sample also demonstrated cost-effectiveness. Notably, IOM benefits were unable to overcome the sheer costs associated many litigation scenarios, but the data was severely limited. In the 5,000 iteration PSA, at a WTP of $100,000, 74% of simulations using IOM were cost-effective. Conclusions: The use of IOM in spine surgery is cost-effective in most scenarios examined. In the emerging and rapidly expanding field of value-based medicine, there will be an increased demand for these analyses, ensuring surgeons are empowered to make the best, most sustainable solutions for their patients and the health care system.

A real-world analysis of hybrid CDA and ACDF compared to multilevel ACDF.

BACKGROUND: Multilevel anterior cervical discectomy and fusion (mACDF) is the gold standard for multilevel spinal disease; although safe and effective, mACDF can limit regular spinal motion and contribute to adjacent segment disease (ASD). Hybrid surgery, composed of ACDF and cervical disc arthroplasty, has the potential to reduce ASD by retaining spinal mobility. This study examined the safety of hybrid surgery by utilizing administrative claims data to compare real-world rates of subsequent surgery and post-procedural hospitalization within populations of patients undergoing hybrid surgery versus mACDF for multilevel spinal disease. METHODS: This observational, retrospective analysis used the MarketScan Commercial and Medicare Database from July 2013 through June 2020. Propensity score matched cohorts of patients who received hybrid surgery or mACDF were established based on the presence of spinal surgery procedure codes in the claims data and followed over a variable post-period. Rates of subsequent surgery and post-procedural hospitalization (30- and 90-day) were compared between hybrid surgery and mACDF cohorts. RESULTS: A total of 430 hybrid surgery patients and 2,136 mACDF patients qualified for the study; average follow-up was approximately 2 years. Similar rates of subsequent surgery (Hybrid: 1.9 surgeries/100 patient-years; mACDF: 1.8 surgeries/100 patient-years) were observed for the two cohorts. Hospitalization rates were also similar across cohorts at 30 days post-procedure (Hybrid: 0.67% hospitalized/patient-year; mACDF: 0.87% hospitalized/patient-year). At 90 days post-procedure, hybrid surgery patients had slightly lower rates of hospitalization compared to mACDF patients (0.23% versus 0.42% hospitalized/patient-year; p < 0.05). CONCLUSIONS: Findings of this real-world, retrospective cohort study confirm prior reports indicating that hybrid surgery is a safe and effective intervention for multilevel spinal disease which demonstrates non-inferiority in relation to the current gold standard mACDF. The use of administrative claims data in this analysis provides a unique perspective allowing the inclusion of a larger, more generalizable population has historically been reported on in small cohort studies.

A Prospective Study of Lumbar Facet Arthroplasty in the Treatment of Degenerative Spondylolisthesis and Stenosis: Early Cost-effective Assessment from the Total Posterior Spine System (TOPS™) IDE Study.

Background: Given the increased attention to functional improvement in spine surgery as it relates to motion preservation, activities of daily living, and cost, it is critical to fully understand the healthcare economic impact of new devices being tested in large FDA randomized controlled trials (RCT). The purpose of this analysis was to comprehensively evaluate the cost-effectiveness of the novel Total Posterior Spine (TOPS™) System investigational device compared with the trial control group, standard transforaminal lumbar interbody fusion (TLIF). Objective: To evaluate the cost-effectiveness of TOPS™ compared with TLIF. Methods: The study patient population was extracted from a multicenter RCT with current enrollment at n=121 with complete 1-year follow-up. The primary outcome was cost-effectiveness, expressed as the incremental cost-effectiveness ratio. Secondary outcomes were health-related utility, presented as quality-adjusted life-years (QALYs), and cost, calculated in US dollars. Analysis was conducted following Second Panel on Cost-Effectiveness Health and Medicine recommendations. The base case analysis utilized SF-36 survey data from the RCT. Both cost and QALY outcomes were discounted at a yearly rate of 3% to reflect their present value. A cohort Markov model was constructed to analyze perioperative and postoperative costs and QALYs for both TOPS™ and control groups. Scenario, probabilistic, and threshold sensitivity analyses were conducted to determine model discrimination and calibration. Results: The primary time horizon used to estimate cost and health utility was 2 years after index surgery. From a health system perspective, assuming a 50/50 split between Medicare and private payers, the TOPS™ cohort is cost-effective 2 years postoperatively ($6158/QALY) compared with control. At 6 years and beyond, TOPS™ becomes dominant, irrespective of payer mix and surgical setting. At willingness-to-pay thresholds of $100 000/QALY, 63% of all 5000 input parameter simulations favor TOPS, even with a $4000 upcharge vs TLIF. Discussion: The novel TOPS™ device is cost-effective compared with TLIF and becomes the dominant economic strategy over time. Conclusions: In the emerging, rapidly expanding field of value-based medicine, there will be an increased demand for these analyses, ensuring surgeons are empowered to make the best, most sustainable solutions for their patients and society.

Acute Implantation of a Bioresorbable Polymer Scaffold in Patients With Complete Thoracic Spinal Cord Injury: 24-Month Follow-up From the INSPIRE Study.

BACKGROUND: Based on 6-month data from the InVivo Study of Probable Benefit of the Neuro-Spinal Scaffold for Safety and Neurological Recovery in Patients with Complete Thoracic Spinal Cord Injury (INSPIRE) study (NCT02138110), acute implantation of an investigational bioresorbable polymer device (Neuro-Spinal Scaffold [NSS]) appeared to be safe in patients with complete thoracic spinal cord injury (SCI) and was associated with an ASIA Impairment Scale (AIS) conversion rate that exceeded historical controls. OBJECTIVE: To evaluate outcomes through 24 months postimplantation. METHODS: INSPIRE was a prospective, open-label, multicenter, single-arm study. Eligible patients had traumatic nonpenetrating SCI with a visible contusion on MRI, AIS A classification, neurological level of injury at T2-T12, and requirement for open spine surgery ≤96 hours postinjury. RESULTS: Nineteen patients underwent NSS implantation. Three patients had early death determined by investigators to be unrelated to the NSS or its implantation procedure. Seven of 16 evaluable patients (44%) had improvement of ≥1 AIS grade at 6 months (primary end point) to AIS B (n = 5) or AIS C (n = 2). Three patients with AIS B at 6 months had further neurological improvement to AIS C by 12 (n = 2) and 24 (n = 1) months, respectively; none have deteriorated per latest available follow-up. No unanticipated or serious adverse device effects were reported. CONCLUSION: In this small group of patients with complete thoracic SCI, acute NSS implantation within the spinal cord appeared to be safe with no long-term neurological issues identified during the 24-month follow-up. Patients remain stable, with additional AIS conversions observed in some patients at 12 months and beyond. These data further support the safety and probable benefit of NSS implantation in this patient population.

2-Level Anterior Cervical Arthrodesis With Integrated Spacer and Plate vs Traditional Anterior Spacer and Plate System.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) is a common surgery to treat cervical degenerative disc disease. Use of an anterior spacer and plate system (ASPS) results in increased disc height, higher fusion rate, lower subsidence rate, and lower complication rate than a spacer alone.1,2 However, anterior cervical plating is associated with complications, such as dysphagia, plate-screw dislodgment, soft tissue injury, neural injury, and esophageal perforation.3-9 To potentially reduce these drawbacks, integrated spacer and plate (ISP) systems have gained popularity. METHODS: From November 2009 to October 2013, a total of 84 consecutive patients who underwent 2-level ACDF using ISP or ASPS were reviewed for clinical and radiographic outcomes. Patient-reported visual analog scale (VAS) and Neck Disability Index (NDI) scores, fusion rates, and hardware failure were determined at 1, 3, 6, 12, and 24 months after surgery. RESULTS: Forty-three patients received ISP and 41 patients received ASPS. There were no significant differences in patient demographics between the 2 groups. Perioperative characteristics were similar, except for operative time. Postoperatively, no significant differences in VAS or NDI scores or fusion status were found. At the proximal surgical level only, there was a trend toward an earlier observed radiographic fusion rate in ASPS vs ISP, but this finding was not statistically significant (P = 0.092). One case of long-term dysphagia was reported in each group. Neither group had implant failures up to 2 years. CONCLUSIONS: The ISP system for 2-level ACDF compared to traditional ASPS has comparable clinical and radiographic outcomes up to 2 years postoperatively. There may be a trend toward an earlier observed radiographic fusion in the ASPS group, but there was no difference in long-term dysphagia rate. CLINICAL RELAVANCE: Integrated spacer and traditional anterior spacer for 2-level ACDF has similar clinical and radiographical outcome.

Efficacy of Human Adipose-Derived Stem Cells in Spinal Fusion in a Rat Ovariectomy Osteoporosis Model.

AIM: To evaluate the efficacy of human adipose-derived stem cells (h-ADSCs) in spinal fusion in an osteoporotic rat model. MATERIAL AND METHODS: Female Sprague-Dawley rats (n=40) underwent ovariectomy and were then randomly assigned into two groups: ovariectomy (OVX) (OVX + fusion) and h-ADSCs (OVX + fusion + h-ADSCs). Six weeks after OVX, we performed bilateral lumbar spinal fusion using the autologous iliac bone with or without administration of h-ADSCs. The efficacy of the spinal fusion was then assessed using manual palpation, lateral ending, morphogenic examinations, and histology six weeks the after fusion procedure. RESULTS: Fusion bed volume was different between the two groups but not significantly. However, the fusion bed density was higher in the h-ADSC group than in the OVX group. Manual palpation (70% vs. 40%, p=0.112) and lateral bending (95% vs. 55%, p=0.011) produced higher fusion rates in the h-ADSC group than in the OVX group. Additionally, a histologic examination revealed new bone formation at the fusion bed between the lamina and implanted iliac crest bone in the h-ADSC group, whereas, in the OVX group, the fusion masses were composed of fibroblastic proliferation. CONCLUSION: Our study demonstrates that the administration of h-ADSCs may have advantages in bone formation and consolidation but does not lead to bone overgrowth. These findings indicate that the administration of h-ADSCs is an alternative and efficient method for spinal fusion.

A study of probable benefit of a bioresorbable polymer scaffold for safety and neurological recovery in patients with complete thoracic spinal cord injury: 6-month results from the INSPIRE study.

OBJECTIVE: The aim of this study was to evaluate whether the investigational Neuro-Spinal Scaffold (NSS), a highly porous bioresorbable polymer device, demonstrates probable benefit for safety and neurological recovery in patients with complete (AIS grade A) T2-12 spinal cord injury (SCI) when implanted ≤ 96 hours postinjury. METHODS: This was a prospective, open-label, multicenter, single-arm study in patients with a visible contusion on MRI. The NSS was implanted into the epicenter of the postirrigation intramedullary spinal cord contusion cavity with the intention of providing structural support to the injured spinal cord parenchyma. The primary efficacy endpoint was the proportion of patients who had an improvement of ≥ 1 AIS grade (i.e., conversion from complete paraplegia to incomplete paraplegia) at the 6-month follow-up visit. A preset objective performance criterion established for the study was defined as an AIS grade conversion rate of ≥ 25%. Secondary endpoints included change in neurological level of injury (NLI). This analysis reports on data through 6-month follow-up assessments. RESULTS: Nineteen patients underwent NSS implantation. There were 3 early withdrawals due to death, which were all determined by investigators to be unrelated to the NSS or the implantation procedure. Seven of 16 patients (43.8%) who completed the 6-month follow-up visit had conversion of neurological status (AIS grade A to grade B [n = 5] or C [n = 2]). Five patients showed improvement in NLI of 1 to 2 levels compared with preimplantation assessment, 3 patients showed no change, and 8 patients showed deterioration of 1 to 4 levels. There were no unanticipated or serious adverse device effects or serious adverse events related to the NSS or the implantation procedure as determined by investigators. CONCLUSIONS: In this first-in-human study, implantation of the NSS within the spinal cord appeared to be safe in the setting of surgical decompression and stabilization for complete (AIS grade A) thoracic SCI. It was associated with a 6-month AIS grade conversion rate that exceeded historical controls. The INSPIRE study data demonstrate that the potential benefits of the NSS outweigh the risks in this patient population and support further clinical investigation in a randomized controlled trial. Clinical trial registration no.: NCT02138110 (clinicaltrials.gov).

A Randomized Controlled Trial of Local Delivery of a Rho Inhibitor (VX-210) in Patients with Acute Traumatic Cervical Spinal Cord Injury.

Acute traumatic spinal cord injury (SCI) can result in severe, lifelong neurological deficits. After SCI, Rho activation contributes to collapse of axonal growth cones, failure of axonal regeneration, and neuronal loss. This randomized, double-blind, placebo-controlled phase 2b/3 study evaluated the efficacy and safety of Rho inhibitor VX-210 (9 mg) in patients after acute traumatic cervical SCI. The study enrolled patients 14-75 years of age with acute traumatic cervical SCIs, C4-C7 (motor level) on each side, and American Spinal Injury Association Impairment Scale (AIS) Grade A or B who had spinal decompression/stabilization surgery commencing within 72 h after injury. Patients were randomized 1:1 with stratification by age (<30 vs. ≥30 years) and AIS grade (A vs. B with sacral pinprick preservation vs. B without sacral pinprick preservation). A single dose of VX-210 or placebo in fibrin sealant was administered topically onto the dura over the site of injury during decompression/stabilization surgery. Patients were evaluated for medical, neurological, and functional changes, and serum was collected for pharmacokinetics and immunological analyses. Patients were followed up for up to 12 months after treatment. A planned interim efficacy-based futility analysis was conducted after ∼33% of patients were enrolled. The pre-defined futility stopping rule was met, and the study was therefore ended prematurely. In the final analysis, the primary efficacy end-point was not met, with no statistically significant difference in change from baseline in upper-extremity motor score at 6 months after treatment between the VX-210 (9-mg) and placebo groups. This work opens the door to further improvements in the design and conduct of clinical trials in acute SCI.

Safety and efficacy of riluzole in patients undergoing decompressive surgery for degenerative cervical myelopathy (CSM-Protect): a multicentre, double-blind, placebo-controlled, randomised, phase 3 trial.

BACKGROUND: Degenerative cervical myelopathy represents the most common form of non-traumatic spinal cord injury. This trial investigated whether riluzole enhances outcomes in patients undergoing decompression surgery for degenerative cervical myelopathy. METHODS: This multicentre, double-blind, placebo-controlled, randomised, phase 3 trial was done at 16 university-affiliated centres in Canada and the USA. Patients with moderate-to-severe degenerative cervical myelopathy aged 18-80 years, who had a modified Japanese Orthopaedic Association (mJOA) score of 8-14, were eligible. Patients were randomly assigned (1:1) to receive either oral riluzole (50 mg twice a day for 14 days before surgery and then for 28 days after surgery) or placebo. Randomisation was done using permuted blocks stratified by study site. Patients, physicians, and outcome assessors remained masked to treatment group allocation. The primary endpoint was change in mJOA score from baseline to 6 months in the intention-to-treat (ITT) population, defined as all individuals who underwent randomisation and surgical decompression. Adverse events were analysed in the modified intention-to-treat (mITT) population, defined as all patients who underwent randomisation, including those who did not ultimately undergo surgical decompression. This study is registered with ClinicalTrials.gov, NCT01257828. FINDINGS: From Jan 31, 2012, to May 16, 2017, 408 patients were screened. Of those screened, 300 were eligible (mITT population); 290 patients underwent decompression surgery (ITT population) and received either riluzole (n=141) or placebo (n=149). There was no difference between the riluzole and placebo groups in the primary endpoint of change in mJOA score at 6-month follow-up: 2·45 points (95% CI 2·08 to 2·82 points) versus 2·83 points (2·47 to 3·19), difference -0·38 points (-0·90 to 0·13; p=0·14). The most common adverse events were neck or arm or shoulder pain, arm paraesthesia, dysphagia, and worsening of myelopathy. There were 43 serious adverse events in 33 (22%) of 147 patients in the riluzole group and 34 serious adverse events in 29 (19%) of 153 patients in the placebo group. The most frequent severe adverse events were osteoarthrosis of non-spinal joints, worsening of myelopathy, and wound complications. INTERPRETATION: In this trial, adjuvant treatment for 6 weeks perioperatively with riluzole did not improve functional recovery beyond decompressive surgery in patients with moderate-to-severe degenerative cervical myelopathy. Whether riluzole has other benefits in this patient population merits further study. FUNDING: AOSpine North America.

Remote Virtual Spinal Evaluation in the Era of COVID-19.

BACKGROUND: With the COVID-19 pandemic disrupting many facets of our society, physicians and patients have begun using telemedicine as a platform for the delivery of health care. One of the challenges in implementing telemedicine for the spine care provider is completing a comprehensive spinal examination. Currently, there is no standardized methodology to complete a full spinal examination through telemedicine. METHODS: We propose a novel, remote spinal examination methodology that is easily implemented through telemedicine, where the patient is an active participant in the successful completion of his or her examination. This type of examination has been validated in a neurology setting. To facilitate the telemedicine visit, we propose that video instruction be shared with the patient prior to the telemedicine visit to increase the efficacy of the examination. RESULTS: Since the issuance of stay-at-home order across the states, many spine practices around the country have rapidly adopted and increased their telemedicine program to continue provide care for patients during COVID-19 pandemic. At a tertiary academic center in a busy metropolitan area, nearly 700 telemedicine visits were successfully conducted during a 4-week period. There were no remote visits being done prior to the shutdown. CONCLUSIONS: Implementation of our proposed remote spinal examination has the potential to serve as a guideline for the spine care provider to efficiently assess patients with spine disease using telemedicine. Because these are only suggestions, providers should tailor examination to each individual patient's needs. LEVEL OF EVIDENCE: V. CLINICAL RELEVANCE: It is likely that physicians will incorporate telemedicine into health care delivery services even after the COVID-19 pandemic subsides because of telemedicine's efficiency in meeting patient needs. Using the standard maneuvers provided in our study, spine care providers can perform a nearly comprehensive spine examination through telemedicine. Further studies will be needed to validate the reproducibility and reliability of our methodology.

Headache Relief Is Maintained 7 Years After Anterior Cervical Spine Surgery: Post Hoc Analysis From a Multicenter Randomized Clinical Trial and Cervicogenic Headache Hypothesis.

OBJECTIVE: To evaluate whether anterior cervical spine surgery offers sustained (7 years) relief in patients with cervicogenic headaches (CGHs), and evaluate the difference between cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) for 1 and 2-level surgeries from a multicenter randomized clinical trial. METHODS: A post hoc analysis was performed of 575 patients who underwent one or 2-level CDA or ACDF for symptomatic cervical spondylosis as part of a prospective randomized clinical trial. Assessment of pain and functional outcome was done with the Neck Disability Index (NDI) in the trial. We used the NDI headache component to assess headache outcome. RESULTS: For both 1- and 2-level CDA and ACDF groups, there was significant headache improvement from preoperative baseline out to 7 years (p < 0.0001). For 1-level surgeries, headache improvement was similar for both groups at the 7-year point. For 2-level treatment, CDA patients had significantly improved headache scores versus ACDF patients at the 7-year point (p = 0.016). CONCLUSION: The headache improvement noted at early follow-up was sustained over the long-term period with ACDF and CDA populations. In the case of 2-level operations, CDA patients demonstrated significantly greater benefit compared to ACDF patients over the long-term. Sinuvertebral nerve irritation at the unco-vasculo-radicular junction and anterior dura may be the cause of CGH. Therefore, it is possible that improved cervical kinematics and preservation of range of motion at adjacent uncovertebral joints in CDA may contribute to the observed difference between the groups.

Effects of pre-contoured and in situ contoured rods on the mechanical strength and durability of posterior cervical instrumentation: a finite-element analysis and scanning electron microscopy investigation.

STUDY DESIGN: Finite-element analysis. OBJECTIVES: Intraoperative contouring of rods is a common procedure for spine surgeons to match the native curvature of the spine, but it may lead to premature weakening of the rod. This study investigated the effect of different bending methods on rod fatigue performance. Rod failure in the cervical spine is of clinical concern, particularly when spanning the cervicothoracic region and when considering corrective osteotomies for deformity correction and global spinal alignment. METHODS: Finite-element models were developed to simulate rod bending (3.5 mm D, 40 mm L) to achieve a 23° angle with 3 different bending methods: French single, multiple bending, and in situ bending. Simulations were conducted in 4 steps: rod bending, rod spring back, residual stress relaxation, and F1717 mechanical test simulation. RESULTS: French single bending resulted in the highest residual stress concentrations for both titanium (TiAlV) and cobalt chrome (CoCr) at 783 MPa and 507 MPa, respectively. During F1717 test simulation, the French single bent rod had its highest tensile stress in the middle, with 917 MPa and 623 MPa, respectively, for TiAlV and CoCr, compared to in situ (580 MPa and 586 MPa for TiAlV and CoCr) and the French multiple bent rod (765 MPa and 619 MPa for TiAlV and CoCr). The computational model found that CoCr rods made the construct least prone to deformation. CONCLUSIONS: French single bend with TiAlV rods put the construct at highest risk of failure. CoCr rods led to minimal physical changes in microstructure while showing evidence of flattening.

The Optimal Surgical Approach to Intradural Spinal Tumors: Laminectomy or Hemilaminectomy?

Objective Traditionally, laminectomy has been the preferred surgical approach for the resection of intradural spinal tumors. Recent trends towards minimally invasive techniques have generated interest in hemilaminectomy as an effective alternative surgical approach to resect spinal tumors. However, it remains unclear if the potential benefits of hemilaminectomies, used in other routine spinal procedures, apply to intradural spinal tumors. This report presents a six-year single institutional analysis of open resection of intradural tumors using laminectomies as compared to hemilaminectomies. Methods A single institution, multisurgeon, retrospective review of 52 patients undergoing resection of intradural spinal tumors over a six-year period was performed. Estimated blood loss, operative time, post-operative complications, length of stay, and post-operative clinical spinal instability were analyzed and compared between the two surgical techniques. Results The mean follow-up was 34 and 20 months for the laminectomy and hemilaminectomy groups, respectively. There was no statistically significant difference in operative times between the two groups (hemilaminectomy: 250.13±76.44 minutes, laminectomy: 244.49±92.85 minutes; p=0.43). Similarly, there was no difference in overall estimated blood loss (hemilaminectomy: 125±74 cc, laminectomy: 256.05±320.8 cc; p=0.27) or mean hospital length of stay (hemilaminectomy: 4.00±2.12 days, laminectomy: 5.26±3.0 days; p=0.60). No patient in either surgical group had post-operative evidence of clinical spinal instability. Conclusion Hemilaminectomy is a viable approach for the resection of intradural spinal tumors, with similar rates of post-operative complications to laminectomy when using an open surgical approach. The laminectomy allows for bilateral exposure of the entire spinal canal and neural foramina; and continues to be the preferred method for resection of large tumors with complex morphology.

Risk Factors of Secondary Lumbar Discectomy of a Herniated Lumbar Disc after Lumbar Discectomy.

OBJECTIVE: To study risk factors of secondary lumbar discectomy (LD) for recurrent herniated lumbar disc (HLD) and identify methods to lower the rate of recurrence. METHODS: Data from 160 patients who underwent primary LD were collected retrospectively. Demographic features, radiologic findings including Pfirrmann disc degeneration, and surgical information were analyzed to compare risks between revision and non-revision patients. RESULTS: The revision rate was 15% (24 patients), and the mean follow-up was 28.3 months. HLD recurrence was not related to any demographic characteristics. Primary and secondary LD were most common at the L4-5 level, but the level of operation was not significantly associated with revision. Primary LD most commonly had a Pfirrmann disc degeneration grade of 3, followed by 4. For recurrent HLD, Pfirrmann grade 4 was most common and was statistically significant (p<0.05). A body mass index (BMI) over 30 was considered obese and was significantly related with HLD revision (p<0.05). CONCLUSION: Patients with high BMI or severe disc degeneration should be informed of HLD revision.

Stem and progenitor cell microenvironment for bone regeneration and repair.

Stem cells reside in their native microenvironment, which provides dynamic physical and chemical cues essential to their survival, proliferation and function. A typical cell-based therapeutic approach requires the mesenchymal stem cells (MSC) to depart their native microenvironment, transplant to in-vivo environment, differentiate toward multiple lineages and participate in bone formation. The long-term survival, function and fate of MSC are dependent on the microenvironment in which they are transplanted. Transplantation of morselized autologous bone, which contains both stem cells and their native microenvironment, results in a good clinical outcome. However, implantation of bone graft substitutes does not provide the complete and dynamic microenvironment for MSC. Current bone graft therapeutics may need to be improved further to provide an optimal engineered MSC microenvironment.

Hyper-Crosslinked Carbohydrate Polymer for Repair of Critical-Sized Bone Defects.

This study evaluated the safety and efficacy of a novel hyper-crosslinked carbohydrate polymer (HCCP) for the repair of critical-sized bone defects in comparison to two alternative treatments: autologous bone and poly(lactide-co-glycolide) with hyaluronic acid (PLGA/HA). Bilateral critical-sized defects were created in the lateral femoral condyles of skeletally mature New Zealand White rabbits, and they were subsequently implanted with HCCP, PLGA/HA, or autologous bone in a randomized manner. Clinical and behavioral observations were made daily, and radiological and histopathological evaluations were performed at 4, 10, and 16 weeks postimplantation. Defects implanted with HCCP showed progressive bone regeneration and bridging of the defect without adverse histological events. No signs of infection or inflammation associated with the implant material were observed in all animals that received HCCP implantation. A radiographic assessment performed at 16 weeks post-implantation showed significantly higher bone density and volume in defects implanted with HCCP compared to PLGA/HA. No statistically significant difference was observed in bone density and volume between HCCP and autologous bone. These findings demonstrate that HCCP is biocompatible, osteoconductive, and capable of promoting bone regeneration in vivo; therefore, it is suitable for both tissue engineering and the repair of critical-sized bone defects.

DuraSeal Exact Is a Safe Adjunctive Treatment for Durotomy in Spine: Postapproval Study.

STUDY DESIGN: A nonrandomized, two-armed prospective study. OBJECTIVE: Water-tight dural closure is paramount to the prevention of cerebrospinal fluid (CSF) leakage and associated complications. Synthetic polyethylene glycol (PEG) hydrogel has been used as an adjunct to sutured dural repair; however, its expansion postoperatively is a concern for neurological complications. A low-swell formulation of PEG sealant was introduced as DuraSeal Exact Spine Sealant System (DESS). A Post-Approval Study was performed primarily to evaluate the safety and efficacy of DESS for spinal dural repair compared to current alternatives, in a large patient population, reflecting a real-world practice. METHODS: A total of 36 sites in the United States enrolled 429 patients treated with DESS as an adjunct to dural repair in the spinal sealant group and 406 patients treated with all other modalities in the control arm, from October 2011 to June 2016. The primary endpoint was the incidence of CSF leak within 90 days of operation. The secondary endpoints evaluated were deep surgical site infection and neurological serious adverse events. RESULTS: The CSF leakage in the DESS group (6.6%) was not significantly different from the control group (6.5%) (p = .83), and there was no significant difference in the time to first leak. The two groups had no significant differences in deep surgical site infection (1.6% versus control 2.1%, p = .61) or proportion of subjects with neurological serious adverse events (2.9% versus control 1.6%, p = .516). CONCLUSIONS: DuraSeal Exact Spinal Sealant is safe when compared to current alternatives for spinal dural repair.

Reduction of direct costs in high-risk lumbar discectomy patients during the 90-day post-operative period through annular closure.

PURPOSE: Despite being an extremely successful procedure, recurrent disc herniation is one of the most common post-discectomy complications in the lumbar spine and contributes significant health care and socioeconomic costs. Patients with large annular defects are at a high risk for reherniation, but an annular closure device (ACD) has been designed to reduce reherniation risk in this population and may, in turn, help control direct health care costs after discectomy. PATIENTS AND METHODS: This analysis examined the 90-day post-discectomy cost estimates among ACD-treated (n=272) and control (discectomy alone; n=278) patients in a randomized controlled trial (RCT). Direct medical costs were estimated based on 2017 Humana and Medicare claims. Index discectomies were assumed to occur in an outpatient (OP) setting, whereas repeat discectomies were assumed to be 60% in OP and 40% in inpatient (IP). A sensitivity analysis was performed on this assumption. The device cost was not included in the analysis in order to focus on costs in the 90-day post-operative period. RESULTS: Within 90 days of follow-up, post-operative complications occurred in 3.3% of the ACD patients and 8.6% of the control patients (P=0.01). The average 90-day cost to treat an ACD patient was $10,257 compared to $11,299 per control patient for a 80:20 distribution of Commercial:Medicare coverage ($1,042 difference). This difference varied from $687 with 100% Medicare to $1,132 with 100% Commercial coverage. Varying the IP vs OP distribution resulted in a cost difference range of $968 to $1,156 with the ACD. CONCLUSION: Augmenting discectomy with an ACD in high-risk patients with a large annular defect reduced reherniation and reoperation rates, which translated to a reduction of direct health care costs between $687 and $1,156 per patient during the 90-day post-operative period. Large annular defect patients are an easily identifiable high-risk population. Operative strategies that reduce complication risks in these patients, such as the ACD, could be advantageous from both patient care and economic perspectives.