Risk Factors of Extended Hospital Stay After One-Level Anterior Cervical Discectomy Fusion or Disc Replacement: Results from 1004 Patients in Food and Drug Administration Trials.

BACKGROUND: Extended length of stay (LOS) after surgery is costly to the health care system and can be distressing to the patient and family. Previous studies have shown conflicting data on factors associated with increased LOS and are limited by using multiple different surgeries. Our study seeks to analyze factors that are associated with extended LOS. OBJECTIVE: The objective of this study was to analyze data from 2 Food and Drug Administration trials of one-level cervical surgery to identify risk factors that are associated with extended LOS in the hospital. METHODS: Extended LOS was defined to be >1 day. Patients with LOS ≤1 day were compared with those with LOS >1 day. Data from the BRYAN and Prestige ST Trial (n = 1004) were analyzed. Subjects with LOS ≤1 day were compared with those with LOS >1 day. Variables analyzed for their effect on LOS included demographic characteristics, patient-reported outcome measures, preoperative medical conditions, preoperative neurologic status, and intraoperative factors. RESULTS: A total of 912 patients (90.84%) had an LOS ≤1 day and 92 patients (9.16%) had an extended LOS >1 day. Weak narcotic medication use (P = 0.021; odds ratio [OR], 1.72), Nurick gait (P = 0.019; OR, 1.796), and operative time (P < 0.0001; OR, 2.062) were found to significantly affect LOS. CONCLUSIONS: Nurick gait, operative time, and history of weak narcotic use are associated with extended hospital stay. These data may be useful in preoperatively counseling patients, developing quality metrics for hospitals, and helping create financial models for cost/diagnosis-related group reimbursement for single-level anterior cervical surgery.

Long-Term Comparison of Health Care Utilization and Reoperation Rates in Patients Undergoing Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion for Cervical Degenerative Disc Disease.

BACKGROUND: Thus study was a retrospective cohort analysis. Anterior cervical discectomy and fusion (ACDF) has been the gold-standard procedure for single-level degenerative disc disease (DDD). Recently, cervical disc arthroplasty (CDA) has become increasingly prevalent as an alternative intervention. OBJECTIVE: To examine the long-term costs and reoperation rates associated with CDA and ACDF for the treatment of single-level DDD. METHODS: In the present study, we performed a retrospective cohort analysis using the MarketScan database of patients who underwent either ACDF or CDA between 2007 and 2011 and had 5 years postsurgery follow-up. Outcomes related to the health care utilization, cost, and reoperation were analyzed after propensity score matching (PSM). RESULTS: Of 12,434 patients, 12,099 underwent ACDF and 335 CDA. Length of hospital stay and initial hospitalization cost was higher after ACDF compared with CDA. More patients undergoing CDA had early physical therapy compared with patients undergoing ACDF (CDA 30.15% vs. ACDF 22.39%; P = 0.0176). Five years after surgery, there was no significant difference in overall payments between patients undergoing ACDF and patients undergoing CDA. Reoperation rates were comparable at 5 years after the index procedure (CDA 8.06% vs. ACDF 9.25%; P = 0.5862). Patients who underwent ACDF showed decreased use of tramadol after surgery (15.09% before surgery vs. 9.55% after surgery; P < 0.0001). CONCLUSIONS: We found no difference in health care utilization between ACDF and CDA procedures for DDD 5 years after surgery. Also, there was no difference in reoperation rates during the study period. ACDF resulted in significant reduction in overall opioid use after versus before procedure.

Clinical and radiological evaluation of cervical disc arthroplasty with 5-year follow-up: a prospective study of 384 patients.

BACKGROUND: Cervical total disc replacement was developed to avoid known complications of cervical fusion. The purpose of this paper was to provide 5-year follow-up results of an ongoing prospective study after implantation of cervical disc prosthesis. METHODS: Three hundred and eighty-four patients were treated using Mobi-C cervical disc (Zimmer Biomet, Troyes, France) and included in a prospective multicentre study. Routine clinical and radiological examinations were reported preoperatively and postoperatively with up to 5-year follow-up. Complications and revision surgeries were also explored. RESULTS: Results at 5 years showed significant improvement in all clinical outcomes (NDI, VAS for arm and neck pain, SF-36 PCS and MCS). Motion at index level increased significantly from 6.0° preoperatively to 8.0°, and 72.1% of the implanted segments were still mobile (referring to threshold of ROM > 3°). Proximal and distal adjacent discs showed no significant change in average motion 5 years after surgery compared to baseline. Ossification resulting in complete fusion was observed in 16.4% of the implanted segments. Distal and proximal adjacent disc degeneration occurred in 42.2% and 39.1% of patients, respectively. Complications rate was 8.9%, and 1.5% of the patients had reoperation at the index level. Surgery rate of adjacent discs was 2.9%. An increased percentage of working patients and a decrease in medication consumption were observed. At 5 years, 93.3% patients were satisfied regarding the overall outcome. CONCLUSIONS: In this study, favourable 5-year follow-up clinical and radiological outcomes were observed with a low rate of adjacent level surgery. These slides can be retrieved under Electronic Supplementary Material.

Safety of Outpatient Single-level Cervical Total Disc Replacement: A Propensity-Matched Multi-institutional Study.

STUDY DESIGN: A retrospective cohort comparison study. OBJECTIVE: The aim of this study was to investigate the perioperative adverse event profile of cervical total disc replacement (CTDR) performed as an outpatient relative to inpatient procedure. SUMMARY OF BACKGROUND DATA: Recent reimbursement changes and a push for safe reductions in hospital stay have resulted in increased interest in performing CTDRs in the outpatient setting. However, there has been a paucity of studies investigating the safety of outpatient CTDR procedures, despite increasing frequency. METHODS: Patients who underwent single-level CTDR were identified in the 2005 to 2016 National Surgical Quality Improvement Program database. Outpatient versus inpatient procedure status was defined by length of stay, with outpatient being less than 1 day. Patient baseline characteristics and comorbidities were compared between the two groups. Propensity score matched comparisons were then performed for 30-day perioperative complications and readmissions between the two cohorts. In addition, perioperative outcomes of outpatient single-level CTDR versus matched outpatient single-level anterior cervical discectomy and fusion (ACDF) cases were compared. RESULTS: In total, 373 outpatient and 1612 inpatient single-level CTDR procedures were identified. After propensity score matching was performed to control for potential confounders, statistical analysis revealed no significant difference in perioperative complications between outpatient versus matched inpatient CTDR. Notably, the rate of readmissions was not different between the two groups. In addition, there was no difference in rates of perioperative adverse events between outpatient single-level CTDR versus matched outpatient single-level ACDF. CONCLUSION: The perioperative outcomes evaluated in the current study support the conclusion that, for appropriately selected patients, single-level CTDR can be safely performed in the outpatient setting without increased rates of 30-day perioperative complications or readmissions compared with inpatient CTDR or outpatient single-level ACDF. LEVEL OF EVIDENCE: 3.

Health-related quality of life in patients undergoing lumbar total disc replacement: A comparison with the general population.

OBJECTIVES: In up to half of the cases, low back pain (LBP) is thought to be related to a degeneration of the lumbar disc. Lumbar total disc replacement (LTDR) emerged as an alternative to fusion, but its use and indications are still subject to debate. The purpose of this paper was to compare Health-related Quality of life (HRQOL) in patients undergoing LTDR for one or two-level degenerative disc disease (DDD) with the paired age and gender general population values and to assess functional disability and residual pain at one year after the surgical procedure. MATERIAL AND METHODS: A series of 51 patients operated on for a one or two level DDD, were evaluated at one year after the surgical procedure. HRQOL was compared to that of paired age and gender general population using the EQ-5D-5L questionnaire. Disability, back (BP) and leg pain (LP) were compared to the preoperative values. RESULTS: ODI showed a mean improvement of 31.78 (p<0.001, 95% CI 27.39-36.17), BP-VAS of 5.29/10 (95% CI 4.56-6.02), LP-VAS of 4.03/10 (95% CI 3.15-4.92) at one year compared to the preoperative assessment. HRQOL had similar values to the general population in 32 patients and inferior in 19 patients. "Pain" was the HRQOL dimension in which most of the patients had inferior results compared to data from the general population. Patients with previous spinal surgery had lower improvements in HRQOL index, disability, and pain than those without previous surgery. CONCLUSIONS: We found that the majority of patients improved their HQOL to values similar to those of the general population. Disability and pain are significantly reduced compared to preoperative evaluations. Larger scale studies are needed to identify the best candidates for LTDR.

Outcomes Following Multilevel Cervical Disc Arthroplasty in the Young Active Population.

BACKGROUND: Cervical radiculopathy is a common disorder that portends significant morbidity. The presence of radiculopathy can have a debilitating effect on patients as well as a significant economic impact. Active duty military patients with increased physical occupational demands can be significantly impacted by cervical disease. The resulting disability can have a strong negative impact on operational readiness. Several studies have demonstrated comparably good functional outcomes between cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion for single-level disease. To date, no study has specifically evaluated the functional and occupational outcomes following adjacent 2-level CDA in a young, active patient population as represented by the active duty military population. PURPOSE: To evaluate functional and occupational outcomes following adjacent 2-level CDA for cervical radiculopathy in the U.S. military population. We hypothesized that this population would have excellent symptomatic relief at the cost of a low return to duty rate. METHODS: We performed a case series with prospective follow-up of all patients who underwent adjacent two-level CDA at a single institution from 2011 to 2014. Each patient completed the Neck Disability Index questionnaire to assess functional outcome. Primary outcomes of interest were return to active military duty and complications. RESULTS: Follow-up was available for 18 of 21 (85.7%) patients. At an average follow-up of 21.4 ± 11.1 months, 12 patients (66.7%) reported complete symptomatic relief and were able to return to preoperative levels of function. Average self-reported pain score improved from 8.3 preoperatively to 1.1 postoperatively, and average postoperative Neck Disability Index score was 15.5 compared to 37.0 for those who medically retired. Radiographic analysis did not show any evidence of subsidence, migration of hardware, or heterotopic ossification. The average return to duty time was 9.6 weeks. DISCUSSION: We demonstrate that adjacent two-level CDA is capable of providing predictable symptomatic relief and maintenance of a high-demand preoperative level of function for cervical radiculopathy among a population of young and highly active individuals. Adjacent two-level CDA offers significant relief of symptoms with low risk of complication in a young, active, and high-demand cohort such as the U.S. military. Adjacent two-level CDA can be performed with the expectation of improving function, relieving symptoms, returning to preoperative levels of activity, and maintaining operational readiness.

Early experience with lateral lumbar total disc replacement: Utility, complications and revision strategies.

Lumbar total disc replacement (TDR) is an alternative to interbody fusion for the treatment of symptomatic degenerative disc disease. Traditionally, lumbar TDR is performed via an anterior retroperitoneal approach with regional risks of vascular and visceral injury. The direct lateral retroperitoneal, transpsoas approach avoids mobilisation of the great vessels and preserves the anterior longitudinal ligament, thereby maintaining physiological limits on motion. This study aimed to (i) report one site's early experience with lateral lumbar TDR and (ii) provide case examples illustrating the utility, complications and revision strategies of the XL-TDR device. Data were collected prospectively on the first 12 consecutive patients treated with XL-TDR. Patient outcomes included pain (VAS), disability (ODI), and quality of life (SF-36 PCS and MCS). Mean follow-up was 27.5months (range 18-48months). Patients had significant improvements in back (74%) and leg (50%) pain, ODI (69%), PCS (50%) and MCS (39%) (P<0.05). Two patients had early prosthesis dislocation due to prosthesis undersizing. The same skin incision was used to retrieve the XL-TDR and perform salvage lateral lumber interbody fusion, with solid fusion by 12months. Lumbar TDR using the XL-TDR via a lateral transpsoas muscle-splitting approach is a minimally invasive alternative to anterior retroperitoneal exposures for motion preservation. Correct sizing of the XL-TDR and complete contralateral annulectomy with annulus box cutters mitigates the risk of lateral dislocation. Revision surgery for lateral dislocation of the XL-TDR is more straightforward compared to anterior TDR dislocation.

Increased Utilization of Cervical Disk Arthroplasty in University Hospitals with Regional Variation and Socioeconomic Discrepancies.

OBJECTIVE: Treatment of cervical radiculopathy with disk arthroplasty has been approved by the U.S. Food and Drug Administration since 2007. Recently, a significant increase in clinical data including mid- and long-term follow-up has become available, demonstrating the superiority of disk arthroplasty compared with anterior discectomy and fusion. The aim of this project is to assess the nationwide use of cervical disk arthroplasty. METHODS: The University Healthcare Consortium database was accessed for all elective cases of patients treated for cervical radiculopathy caused by disk herniation (International Classification of Diseases [ICD] 722.0) from the fourth quarter of 2012 to the third quarter of 2015. Within this 3-year window, temporal and socioeconomic trends in the use of cervical disk replacement for this diagnosis were assessed. RESULTS: Three thousand four hundred forty-six cases were identified. A minority of cases (10.7%) were treated with disk arthroplasty. Median hospital charges were comparable for cervical disk replacement ($15,606) and anterior cervical fusion ($15,080). However, utilization was seen to increase by nearly 70% during the timeframe assessed. Disk arthroplasty was performed in 8% of patients in 2012 to 2013, compared with 13% of cases in 2015. Disk replacement use was more common for self-paying patients, patients with private insurance, and patients with military-based insurance. There was widespread variation in the use of cervical disk replacement between regions, with a nadir in northeastern states (8%) and a peak in western states (20%). CONCLUSION: Over a short, 3 -year period there has been an increase in the treatment of symptomatic cervical radiculopathy with disk arthroplasty. The authors predict a further increase in cervical disk arthroplasty in upcoming years.

Adjacent segment degeneration following ProDisc-C total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF): does surgeon bias effect radiographic interpretation?

PURPOSE: Many investigators have reported the financial conflicts of interest (COI), which could result in potential bias in the reporting of outcomes for patients undergoing total disc replacement (TDR) rather than anterior cervical discectomy and fusion (ACDF). This bias may be subconsciously introduced by the investigator in a non-blinded radiographic review. The purpose of this study was to determine if bias was present when a group of spine specialists rated adjacent segment degeneration (ASD) following cervical TDR or ACDF. METHODS: Potential bias in the assessment of ASD was evaluated through the reviews of cervical radiographs (pre- and 6 years post-operative) from patients participating in the ProDisc-C FDA trial (ProDisc-C IDE #G030059). The index level was blinded on all radiographs during the first review, but unblinded in the second. Five reviewers (a radiologist, two non-TDR surgeons, and two TDR surgeons), two of whom had a COI with the ProDisc-C trial sponsor, assessed ASD on a three point scale: yes, no, or unable to assess. Intra- and inter-rater reliabilities between all raters were assessed by the Kappa statistic. RESULTS: The intra-rater reliability between reviews was substantial, indicating little to no bias in assessing ASD development/progression. The Kappa statistics were 0.580 and 0.644 for the TDR surgeons (p < 0.0001), 0.718 and 0.572 for the non-TDR surgeons (p < 0.0001), and 0.642 for the radiologist (p < 0.0001). Inter-rater reliability for the blinded review ranged from 0.316 to 0.607 (p < 0.0001) and from 0.221 to 0.644 (p < 0.0001) for the unblinded review. CONCLUSIONS: The knowledge of the surgical procedure performed did not bias the assessment of ASD.

Minimum four-year subsequent surgery rates of cervical disc replacement versus fusion: A meta-analysis of prospective randomized clinical trials.

INSTRUCTION: Anterior cervical discectomy and fusion (ACDF) is a well-accepted surgical management strategy for radiculopathy and/or myelopathy. However, complications sometimes required subsequent surgery at the operated and adjacent levels. Artificial cervical disc replacement (ACDR) has been accepted as the most extensive non-fusion procedure and is designed to preserve motion. However, some specific complications can result in subsequent surgery, thus, attracting the attention of investigators. HYPOTHESIS: Compared with ACDF, ACDR had a lower subsequent surgery rates at both operated and adjacent levels after a minimum of four-years of follow-up. MATERIAL AND METHODS: A meta-analysis was performed with articles published prior to February 2016. Only randomized controlled trials that reported a minimum of 4 years of follow-up with regard to the rates of subsequent surgeries after ACDR compared with ACDF were included in this study. Two reviewers independently screened the articles and data following the PRISMA statement. RESULTS: Our data showed that the pooled overall rate of subsequent surgery at the operated level and adjacent levels was lower in the ACDR group (7.4%) than in the ACDF group (16.8%) (P=0.0006). For subsequent surgery at the operated level, patients who received ACDR had a lower rate of subsequent surgery than patients who received ACDF (P<0.0001). With respect to the adjacent level, ACDR also had fewer subsequent surgeries compared with ACDF (P<0.0001). CONCLUSION: ACDR had significantly fewer subsequent surgical interventions compared with ACDF, However, a review of the literature showed that there were an insufficient number of studies with respect to subsequent surgery with a minimum of 4 years of follow-up. Hence, longer-term, multicenter studies are needed for better evaluation of the rate of subsequent surgery after ACDR. LEVEL OF EVIDENCE: Level I, meta-analysis of high-powered prospective randomized trials.

Implant Migration in Cervical Disk Arthroplasty.

OBJECTIVE: The purpose of this study is to discuss the causes of implant migration after cervical arthroplasty with clinical cases. METHODS: The patients who underwent cervical arthroplasty operations in our department between 2006 and 2015 because of cervical disk disease were retrospectively analyzed. The patients who were determined to be symptomatic of implant migration were evaluated. RESULTS: Symptomatic implant migration was detected in 5 of 163 (0.3%) patients who underwent cervical disk arthroplasty, and these patients also underwent reoperation. In 4 patients who underwent reoperation, the prosthesis was removed, and an anterior fusion was made. The prosthesis was only removed in 1 patient. CONCLUSIONS: The following situations should be considered in the prevention of dislocation and migration of the implant in cervical arthroplasty: protection of the structure of the end plate, selection of the appropriate implant size, and proper surgical construction. In the preoperative period, computed tomography scan may be useful for determining the implant size and details of the bone structure. Foreign body reactions or postoperative trauma may be a rare and unpreventable reason for prosthesis dislocation despite all of the preoperative and perioperative measures and well-made prosthesis designs.

Subsequent surgery rates after cervical total disc replacement using a Mobi-C Cervical Disc Prosthesis versus anterior cervical discectomy and fusion: a prospective randomized clinical trial with 5-year follow-up.

OBJECTIVE Cervical total disc replacement (TDR) has been shown in a number of prospective clinical studies to be a viable treatment alternative to anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic degenerative disc disease. In addition to preserving motion, evidence suggests that cervical TDR may result in a lower incidence of subsequent surgical intervention than treatment with fusion. The goal of this study was to evaluate subsequent surgery rates up to 5 years in patients treated with TDR or ACDF at 1 or 2 contiguous levels between C-3 and C-7. METHODS This was a prospective, multicenter, randomized, unblinded clinical trial. Patients with symptomatic degenerative disc disease were enrolled to receive 1- or 2-level treatment with either TDR as the investigational device or ACDF as the control treatment. There were 260 patients in the 1-level study (179 TDR and 81 ACDF patients) and 339 patients in the 2-level study (234 TDR and 105 ACDF patients). RESULTS At 5 years, the occurrence of subsequent surgical intervention was significantly higher among ACDF patients for 1-level (TDR, 4.5% [8/179]; ACDF, 17.3% [14/81]; p = 0.0012) and 2-level (TDR, 7.3% [17/234]; ACDF, 21.0% [22/105], p = 0.0007) treatment. The TDR group demonstrated significantly fewer index- and adjacent-level subsequent surgeries in both the 1- and 2-level cohorts. CONCLUSIONS Five-year results showed treatment with cervical TDR to result in a significantly lower rate of subsequent surgical intervention than treatment with ACDF for both 1 and 2 levels of treatment. Clinical trial registration no.: NCT00389597 ( clinicaltrials.gov ).

Five-Year Follow-Up of a Prospective, Randomized Trial Comparing Two Lumbar Total Disc Replacements.

STUDY DESIGN: This was a prospective, randomized, controlled, multicenter study. OBJECTIVE: The purpose of this study was to compare outcomes of two lumbar total disc replacements (TDRs) at 5-year follow-up and report results of serum ion level analysis in a subgroup of patients receiving a metal-on-metal implant. SUMMARY OF BACKGROUND DATA: Lumbar TDR has been compared with fusion in several randomized studies, finding TDR noninferior to fusion and superior on some measures. Receiving less attention has been comparing TDR devices. Additionally, there is concern about metal-on-metal implants, with little data available for spine devices. METHODS: The study included 204 patients receiving Kineflex-L (investigational) and 190 receiving CHARITÉ (control). Outcome measure included Oswestry Disability Index, visual analog pain scales (VAS), patient satisfaction, neurological status, complications, reoperations, and a composite success score. Radiographic assessment included range of motion, subsidence, and heterotrophic ossification. In 32 investigational patients, serum ion analysis was performed for cobalt and chromium. These values were compared with Medicines and Healthcare Products Regulatory Agency values to merit monitoring total hip replacement patients for potential wear problems. RESULTS: Mean Oswestry and VAS scores in both groups improved significantly by 6 weeks and remained improved during 5-year follow-up (Oswestry Disability Index, scores in both groups were approximately 60 preoperatively vs. 20 at 2- and 5-year follow-up; P < 0.01; VAS scores improved >50% by 6 weeks and remained significantly improved; P < 0.05). Approximately 11% of both groups underwent reoperation. Radiographic analysis found segmental range of motion decreased at 3 month, then increased through 24 months, and was maintained thereafter. Serum ion level analysis found the greatest mean value at any follow-up point was less than 20% of Medicines and Healthcare Products Regulatory Agency recommended minimum value to merit monitoring hip replacement patients. CONCLUSION: This prospective, randomized study comparing two TDRs found no significant differences in outcomes during 5-year follow-up. Both provided statistically significant improvements by 6 weeks that were maintained. This results support other studies. Serum ion levels in TDR patients were well below the recommended threshold levels to merit monitoring.

Minimum 4-year outcomes of cervical total disc arthroplasty versus fusion: a meta-analysis based on prospective randomized controlled trials.

The prevalence of cervical disc disease is high, and the traditional surgical method of anterior cervical discectomy and fusion (ACDF) carries with it the disadvantages of motion loss at the operated level, and accelerated adjacent level disc degeneration. Preliminary results of the efficacy and reoperative rate comparing TDA versus ACDF have been reported; however, the long-term outcomes of TDA versus ACDF still remain a topic of debate. This review was prepared following the standard procedures set forth by the Cochrane Collaboration organization, and preferred reporting items for systematic reviews and meta-analyses (PRISMA). The only studies included were randomized controlled trials with a minimum of 4 years of follow-up data. The meta-analysis included the neck disability index (NDI), visual analog scale (VAS) of neck and arm pain, SF-36 physical component scores (SF-36 PCS), over success, neurological success, work status, implant-related complications, and secondary surgery events. Four randomized controlled trials meet the inclusion criteria. The long-term improvement of NDI, VAS of neck and arm pain, SF-36 PCS, over success, and neurological success favored the TDA group. The TDA group also had a lower incidence of secondary surgery for both the index level (RR: 0.45 [0.28, 0.72]) and adjacent level (RR: 0.53 [0.33, 0.88]). In this meta-analysis of 4 included RCTs with a minimum 4 years of follow-ups, total disc arthroplasty showed improvements over ACDF as measured by the NDI, VAS of neck and arm pain, and SF-36 PCS.

A Novel Quality-of-Life Utility Index in Patients With Multilevel Cervical Degenerative Disc Disease: Comparison of Anterior Cervical Discectomy and Fusion With Total Disc Replacement.

STUDY DESIGN: Decision analysis from prior randomized controlled trial (RCT) data. OBJECTIVE: To describe the importance of developing baseline utility indices while identifying effective treatment options for cervical spine disease. SUMMARY OF BACKGROUND DATA: Cervical total disc replacement (CTDR) was developed to treat cervical spondylosis while preserving motion. Although anterior cervical discectomy and fusion (ACDF) has been the standard of care, a recent RCT suggested similar outcomes for 2-level disease. The quality-of-life benefit afforded by both CTDR and ACDF has never been fully elucidated. The purpose of our investigation was to better define the changes in utility and perceived value for patients undergoing these procedures. METHODS: Data were derived from LDR's RCT comparing CTDR and ACDF for 2-level cervical disc disease. Using linear regression, we constructed health states on the basis of the stratification of clinical outcomes used in the RCT, namely, neck disability index and visual analogue scale. Data from SF-12 questionnaires, completed preoperatively and at each follow-up visit, were transformed into utilities using the SF-6D mapping algorithm. SAS v.9.3 was used for the analyses. RESULTS: A strong correlation (R = 0.6864, P < 0.0001) was found between neck disability index and visual analogue scale. We constructed 5 distinct health states by projecting neck disability index intervals onto visual analogue scale. A poorer health state was associated with a lower mean utility value whereas a higher health state was associated with a higher mean utility value (P < 0.0001). The difference in preoperative utility between 2-level ACDF and CTDR was not significant (P = 0.1982), and yet, the difference in the postoperative utility between the cohorts was significant (P < 0.05) at every time point collected from 6 to 60 months. CONCLUSION: This is the first instance in which distinct utility values have been derived for validated health states related to cervical spine disease. There is substantial potential for these to become baseline future indices for cost-utility analyses in similar populations. LEVEL OF EVIDENCE: 1.

Does heterotopic ossification affect the outcomes of cervical total disc replacement? A meta-analysis.

STUDY DESIGN: Meta-analysis. OBJECTIVE: The purpose of this study was to answer the following questions: (1) Does heterotopic ossification (HO) negatively influence clinical outcomes after cervical total disc replacement (CTDR)? (2) Should patients be classified into HO and non-HO groups? (3) Is there a more rational classification? SUMMARY OF BACKGROUND DATA: Heterotopic ossification has emerged as a common complication after CTDR and has been an important reason for reoperation, thus limiting the use of the surgery. However, the influence of HO on clinical outcomes after CTDR has not been well established. METHODS: A meta-analysis was conducted with studies identified by searches of MEDLINE, EMBASE, and the Cochrane Library. We calculated the weighted mean differences of the visual analogue scale pain score, Neck Disability Index, and range of motion (ROM). Patients were classified into 2 groups under 3 classifications on the basis of the grade of HO. Results were pooled using a fixed effect model or a random effects model, according to the heterogeneity. RESULTS: There were significant differences in ROM under all 3 classifications. The visual analogue scale pain score and the Neck Disability Index between the patients with and without HO showed no significant difference after CTDR. Significant differences in visual analogue scale pain score were observed when patients were classified into a "high-grade HO" group (McAfee grades 3 or 4 HO) and a "low-grade HO" group (McAfee grade 0, 1, or 2 HO). CONCLUSIONS: The presence of HO is not associated with clinical outcomes after CTDR. However, the severity of HO actually impacts clinical outcomes in an inverse manner, which needs further investigation. It is inappropriate to classify patients on the basis of the presence of HO; further studies of the classifications (ROM-affecting HO vs. ROM-preserving HO; high-grade HO vs. low-grade HO) and cervical stability after CTDR are needed. LEVEL OF EVIDENCE: 2.

Fusion surgery for lumbar degenerative disc disease: still more questions than answers.

COMMENTARY ON: Yoshihara H, Yoneoka D. National trends in the surgical treatment for lumbar degenerative disc disease: United States, 2000 to 2009. Spine J 2015;15:265-71 (in this issue).

[Not Available].

Chronic low back pain is extremelyfrequent and its management is still con troversial among spine physicians. For decades, intervertebral fusion has been considered as the gold- standard. However, non fusion techniques have been developed in order to avoid fusion's complications. Numerous studies have reported satisfactory results of total disc arthro- plasty in the management of lumbar degenerative disc disease. So far it is still dificult to prove the superiority of disc replacement over fusion due to a lack of high level studies. The aim of this work was to try to answers various questions related to that technique which was described twenty years ago.

[Surgery for chronic low back pain: good option? Better than conservative treatment?]

The goal of this article is to assess, using the literature and our own experience, whether surgery is a reasonable option in the management of non-specific or degenerative chronic low back pain. The usual starting points for low back pain are without doubt the intervertebral disc and the facet joints, but the actual etiology is often difficult to determine. Moreover, psychogenic factors may amplify clinical symptoms. In our experience, thorough clinical, psychological, and socioprofessional assessment along with relevant imaging studies, parti- cularly MRI to look for inflammatory disc disease and EOS system to evaluate sagittal balance, leads to surgical indication in only 5 % of the patients with chronic low back pain. In these cases, surgery is aimed at short-circuiting ideally one, but sometimes two, interver- tebral segment by a conventional rigid fixation (arthrodesis), or by more recent non-rigid fixation techniques (disc replacement or interspinous dynamic stabilization). Their preven- tive effect on accelerated degeneration of adjacent segment appears to be moderate at best. The problem is to compare the results of surgical and conservative treatment: The analysis of publications concerning comparative randomized studies and personal studies shows that surgery is useful in only a small proportion of well selected patients with chronic low back pain, compared with physical and cognitive-behavioral management techniques.

National trends in the surgical treatment for lumbar degenerative disc disease: United States, 2000 to 2009.

BACKGROUND CONTEXT: Surgical treatment for lumbar degenerative disc disease (DDD) remains controversial. Options include anterior lumbar interbody fusion, posterior approach fusion procedures such as posterior lumbar interbody fusion (PLIF) and posterolateral lumbar fusion (PLF), anterior and posterior lumbar fusion (APLF), and total disc replacement (TDR). However, the trends during the last decade are uncertain. PURPOSE: To examine the trends in the surgical treatment for lumbar DDD on a national level. STUDY DESIGN: A retrospective analysis of population-based national hospital discharge data collected for the Nationwide Inpatient Sample (NIS). PATIENT SAMPLE: In the NIS from 2000 to 2009, patients aged 18 years or older with primary diagnosis of lumbar/lumbosacral DDD who underwent surgical treatment were included. OUTCOME MEASURES: Trends in the surgical treatment for lumbar DDD. METHODS: Clinical data were derived from the NIS between 2000 and 2009. Patients aged 18 years or older with a primary diagnosis of lumbar/lumbosacral DDD who underwent spinal fusion or TDR were identified. Data regarding patient- and health care system-related characteristics were retrieved and analyzed. RESULTS: A total of 380,305 patients underwent surgical treatment for lumbar DDD between 2000 and 2009. Population adjusted incidence increased 2.4-fold from 2000 to 2009. Among the procedures, APLF increased 3.0-fold and PLIF/PLF increased 2.8-fold. Total disc replacement did not increase significantly. Anterior lumbar interbody fusion was performed in 16.8% of patients, PLIF/PLF in 67.9%, APLF in 13.6%, and TDR in 1.8%. Surgical treatment for lumbar DDD was 1.8 times more common in the Midwest region and 1.7 times more common in the South region than in the Northeast region. Total disc replacement was more common in younger patients and in the Northeast region. Poterior lumbar interbody fusion/PLF was more common in older patients and in the South region. CONCLUSIONS: During the last decade, surgical treatment for lumbar DDD has increased 2.4-fold in the United States. Although all fusion procedures significantly increased, TDR did not increase. Surgical treatment for lumbar DDD was more common in the Midwest and South regions. Trends in the procedures were different depending on the age group and hospital region.