OBJECTIVE:Infection following cervical artificial disc replacement (ADR) is poorly understood, with no established guidelines for prevention or management. This case series aimed to characterize the clinical presentation, microbiological findings, and outcomes of patients with cervical ADR infections. METHODS:The authors conducted a retrospective review of patients at their institution who developed infection following cervical ADR and underwent revision surgery. Data collected included patient demographics, clinical presentation, infective organism, and implant type. Infections were identified based on clinical symptoms and radiological findings and confirmed with microbiological cultures. Infection management, including antibiotic therapy and revision surgery, was recorded. RESULTS:Forty-two cases involving 30 patients were included. Nine patients required 2 or more revision surgeries. Intractable neck pain and upper extremity pain were the most reported clinical symptoms at 83.3% and 38.1%, respectively. Time from symptom onset to diagnosis ranged from 4 days to 208 weeks (mean 44.2 weeks). The top 3 species most commonly isolated from disc space cultures were Cutibacterium acnes (n = 22, 52.4%), Staphylococcus epidermidis (n = 11, 26.2%), and Propionibacterium acnes (n = 7, 16.7%). Cultures were negative in 5 (11.9%) cases. Notably, 27 of 30 patients (90.0%) eventually underwent conversion to fusion. Furthermore, regarding clinical improvement in symptoms, a majority of patients (21/30 patients, 70.0%) experienced symptom improvement or resolution, while 8 (26.7%) had persistent symptom and 1 patient (3.3%) was lost to follow-up. CONCLUSIONS:Infection following cervical ADR is rare but poses significant clinical challenges, with most patients requiring conversion to fusion. Early identification and appropriate management are critical to optimizing patient outcomes. This study reports the largest cohort of patients with infected cervical ADRs to date and provides valuable insights to inform future guidelines for prevention and management.

BACKGROUND:Artificial disc replacement (ADR) has become an evidence-based alternative to traditional fusion surgery. Current guidelines for safe return-to-activity (RTA) levels following surgery have yet to be determined. This Modified Delphi study aimed to establish expert-sourced consensus for safe and optimized RTA recommendations following cervical disc arthroplasty. METHODS:Ten expert spine surgeons with an average of 15 years of surgical experience participated in a 3-round Modified Delphi Method. The first round presented experts with 11 clinical cases and 19 multiple-choice questions regarding recommendations for patient RTA following surgery for 1-, 2-, or 3-level arthroplasty. First-round responses were analyzed and presented in second-round surveys to the experts, who repeated 19 multiple-choice questions. The third round presented consensus recommendation statements derived from the second round for the final assessment of the expert agreement. RESULTS:Experts agreed on 19 of 22 (86.4%) postarthroplasty RTA recommendations. Eight recommendations achieved unanimous agreement; the most robust consensus (95%-100% agreement) included recommendations that patients may return to basic activities such as walking, social activities, sedentary work, air travel, and sexual activity within 2 weeks of arthroplasty surgery and that arthroplasty patients will have a shorter recovery, resuming normal activities sooner than fusion patients. Experts agreed that patients may return to light and heavy physical activity (strong consensus) earlier for 2- and 3-level ADR compared to hybrid constructs. Experts also agreed that ADR patients can resume light physical activity at 4 to 6 weeks and engage in intense conditioning and sport-specific training at 6 weeks. However, a weaker consensus was achieved for returning to physically demanding work at 4 to 6 weeks and high-intensity physical activity/sports at 6 weeks, indicating that individual patient factors and the specific nature of the activity should be considered. CONCLUSION:This study provides the first consensus-based recommendations for RTA following cervical disc arthroplasty. LEVEL OF EVIDENCE: 4:

Cervical total disc replacement (TDR) is intended to preserve motion and reduce adjacent segment degeneration compared to anterior cervical discectomy and fusion (ACDF). The Simplify Cervical Disc (Globus Medical, Audubon, Pennsylvania), a polyetheretherketone (PEEK)-on-ceramic device with titanium-coated endplates, was approved following encouraging short-term outcomes. However, emerging registries and the Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) reports suggest an increase in device failures and revision surgeries, raising concerns about the device’s long-term durability and biological compatibility. We reviewed publicly available FDA MAUDE adverse event reports related to the Simplify disc replacement and the published literature on PEEK-on-ceramic wear mechanisms and titanium coating delamination. Representative clinical cases revised to ACDF procedures were also examined. Device bench testing data from the FDA summary were compared with real-world failure modes. Reported complications were categorized into wear, subsidence, migration, osteolysis, and revision outcomes. Analysis of 96 MAUDE reports revealed diverse complications: osteolysis, device migration, persistent or worsening pain, and intraoperative retrieval difficulties. Histological evaluation of revision specimens demonstrated benign bone and fibrocartilage with foreign material, consistent with PEEK, titanium, and zirconia wear debris, an associated inflammatory reaction, and osteolysis. In vitro data confirm that PEEK-on-ceramic couples generate volumetric wear rates of 0.7–2.1 mm³/Mc, with titanium coating delamination further contributing to particulate load. Bench testing demonstrated mechanical adequacy under idealized conditions. However, retrieval findings highlight wear, coating failure, and osteolysis as potential failure pathways in real-world applications. Clinical outcomes after ACDF revision were favorable, suggesting effective salvage treatment. Despite promising early trial results, the Simplify disc demonstrates concerning failure mechanisms, including PEEK wear, titanium coating delamination, and subsequent osteolysis. The discrepancy between bench testing and retrieval analysis underscores the limitations of preclinical simulation in predicting in vivo wear. Vigilant post-market surveillance, independent registry reporting, and further long-term outcome studies are essential. Until durability is confirmed, cautious patient selection and readiness for revision remain critical in clinical practice.

Background:Despite the growing popularity of cervical disc arthroplasty (CDA), there remains a lack of literature investigating outcomes in older patients and no consensus exists on an age threshold beyond which CDA is not recommended. This study aimed to compare outcomes between patients younger than 65 and those aged 65 and older undergoing CDA. Methods:Patients who underwent CDA at a major spine center (January 2009-December 2023), with at least 1 year of follow-up, were included. Two age-based cohorts were analyzed: younger (<65) and older (≥65). Both single and multilevel disc replacements were considered. Primary outcomes included comparing 90-day complications and all-cause reoperation rates in the 2 cohorts. Secondary outcomes included comparisons of patient characteristics, operative data, and length of stay (LOS). Frequencies, chi-squared analysis, and Student's t-test were used to compare cohorts. Results:A total of 298 CDAs were evaluated among 188 patients. There were 132 patients in the younger cohort (mean age: 48.9±10.2) and 56 in the older cohort (mean age: 69.5±3.8). Cohorts were similar with regards to body mass index, sex, and length of follow up. The overall 90-day complication rate was 23.8%. There was no difference in complication rates (younger: 23.3%, older: 25.0%, p=.60). Older cohort averaged more levels operated (older 1.8±0.6, younger 1.5±0.7, p=.006). The overall reoperation rate was 12.2% (young: 13.5%, older: 8.9%, p=.38). Subsidence was the most common cause of reoperation in both the younger (n=4, 3.0%) and older (n=2, 3.6%) cohorts. Conclusion:In this series, we found no statistically significant differences in 90-day complication or reoperation rates between younger (<65 years) and older (≥65 years) patients undergoing CDA. Subsidence emerged as the most common complication, occurring at similar rates in both cohorts. While further large-scale, long-term analysis is warranted to determine clinical outcomes of CDA in older patients, this study provides comparable complication and reoperation rates as in the younger population.

Background The purpose of this study was to examine facet contact forces above, below, and at surgical index levels induced by artificial disc implantation and compare the results from spiked versus keeled baseplates comprising the arthroplasty device. Methods Human specimens from C2 to C7 were subjected to flexion, extension, and lateral bending prior to, and following random allocation to spiked or keeled cervical arthroplasty at the index (C5-C6), inferior (C6-C7), and superior (C4-C5) levels. Thin film force sensors were inserted unilaterally into the corresponding facets prior to intact testing. Force data was normalized to the minimum forces recorded during each loading mode under each condition, reported as (Max/Min) force ratio and subjected to a 1-way ANOVA with Dunnett's post-hoc tests for comparison to intact specimens. Results Under flexion, compared to intact, all levels displayed a significant reduction in force ratio following a 1- and 3- level implantation for the spiked baseplate device. An increase in force ratio was observed at the index level for a 2-level implantation but was mitigated with the completion of a superior device insertion. No statistical differences were noted for keeled devices. In extension, the spiked baseplate device reduced the force ratio for 1- and 2- level implantations. A 3-level insertion did not alter facet force ratios. For the keeled device, no statistical changes were noted. Lateral bending associated with spiked devices resulted in statistically reduced or non-significant changes in facet loading ratios. The keeled devices did not display significant changes to facet force ratios. Conclusions Implantation of multi-level disc devices can reduce or sustain unaltered facet loading conditions. In general, 3-level arthroplasty statistically reduced or does not increase facet force ratios compared to intact values. The use of spiked versus keel device baseplates is a clinical selection involving anterior/posterior placement and endplate degeneration conditions.

BACKGROUND CONTEXT: Various total disc replacement (TDR) designs have been compared to anterior cervical discectomy and fusion (ACDF) with favorable short and long-term outcomes in FDA -approved investigational device exemption (IDE) trials. The unique design of M6 -C, with a compressible viscoelastic nuclear core and an annular structure, has previously demonstrated favorable clinical outcomes through 24 months. PURPOSE: To evaluate the long-term safety and effectiveness of the M6 -C compressible artificial cervical disc and compare to ACDF at 5 years. STUDY DESIGN: Prospective, multicenter, concurrently and historically controlled, FDAapproved IDE clinical trial. PATIENT SAMPLE: Subjects with one -level symptomatic degenerative cervical radiculopathy were enrolled and received M6 -C (n=160) or ACDF (n=189) treatment as part of the IDE study. Safety outcomes were evaluated at 5 years for all subjects. The primary effectiveness endpoint was available at 5 years for 113 M6 -C subjects and 106 ACDF controls. OUTCOME MEASURES: The primary endpoint of this analysis was composite clinical success (CCS) at 60 months. Secondary endpoints were function and pain (neck disability index, VAS), physical quality of life (SF -36, SF -12), safety, neurologic, and radiographic assessments. METHODS: Propensity score subclassification was used to control for selection bias and match baseline covariates of the control group to the M6 -C subjects. Sixty -month CCS rates were estimated for each treatment group using a generalized linear model controlling for propensity score. RESULTS: At 5 years postoperatively, the M6 -C treatment resulted in 82.3% CCS while the ACDF group showed 67.0% CCS (superiority p=.013). Secondary endpoints indicated that significantly more M6 -C subjects achieved VAS neck and arm pain improvements and showed maintained or improved physical functioning on quality -of -life measures compared to baseline assessments. The M6 -C group -maintained flexion -extension motion, with significantly greater increases from baseline disc height and disc angle than observed in the control group. The rates of M6 -C subsequent surgical interventions (SSI; 3.1%) and definitely device- or procedure -related serious adverse events (SAE failure; 3.1%) were similar to ACDF rates (SSI=5.3%, SAE failure=4.8%; p>.05 for both). CONCLUSIONS: Subjects treated with the M6 -C artificial disc demonstrated superior 5 -year achievement of clinical success when compared to ACDF controls. In addition, significantly more subjects in the M6 -C group showed improved pain and physical functioning scores than observed in ACDF subjects, with no difference in reoperation rates or safety outcomes. (c) 2023 The Authors. Published by Elsevier Inc.

BACKGROUND CONTEXT:The functional goals of cervical disc arthroplasty (CDA) are to restore enough range of motion (ROM) to reduce the risk of accelerated adjacent segment degeneration but limit excessive motion to maintain a biomechanically stable index segment. This motion-range is termed the "Physiological mobility range." Clinical studies report postoperative ROM averaged over all study subjects but they do not report what proportion of reconstructed segments yield ROM in the Physiological mobility range following CDA surgery. PURPOSE:To calculate the proportion of reconstructed segments that yield flexion-extension ROM (FE-ROM) in the Physiological mobility range (defined as 5°-16°) by analyzing the 24-month postoperative data reported by clinical trials of various cervical disc prostheses. STUDY DESIGN/SETTING:Analysis of 24-month postoperative FE-ROM data from clinical trials. PATIENT SAMPLE:Data from 1,173 patients from single-level disc replacement clinical trials of 7 cervical disc prostheses. OUTCOME MEASURES:24-month postoperative index-level FE-ROM. METHODS:The FE-ROM histograms reported in Food and Drug Administration-Investigational Device Exemption (FDA-IDE) submissions and available for this analysis were used to calculate the frequencies of implanted levels with postoperative FE-ROM in the following motion-ranges: Hypomobile (0°-4°), Physiological (5°-16°), and Hypermobile (≥17°). The ROM histograms also allowed calculation of the average ROM of implanted segments in each of the 3 motion-ranges. RESULTS:Only 762 of 1,173 patients (implanted levels) yielded 24-month postCDA FE-ROM in the physiological mobility range (5°-16°). The proportions ranged from 60% to 79% across the 7 disc-prostheses, with an average of 65.0%±6.2%. Three-hundred and two (302) of 1,173 implanted levels yielded ROM in the 0°-4° range. The proportions ranged from 15% to 38% with an average of 25.7%±8.9%. One-hundred and nine (109) of 1,173 implanted levels yielded ROM of ≥17° with a range of 2%-21% and an average proportion of 9.3%±7.9%. The prosthesis with built-in stiffness due to its nucleus-annulus design yielded the highest proportion (103/131, 79%) of implanted segments in the physiological mobility range, compared to the cohort average of 65% (p<.01). Sixty-five of the 350 (18.6%) discs implanted with the 2 mobile-core designs in this cohort yielded ROM≥17° as compared to the cohort average of 9.3% (109/1,173) (p<.05). At 2-year postCDA, the "hypomobile" segments moved on average 2.4±1.2°, those in the "physiological-mobility" group moved 9.4±3.2°, and the hypermobile segments moved 19.6±2.6°. CONCLUSIONS:Prosthesis design significantly influenced the likelihood of achieving FE-ROM in the physiological mobility range, while avoiding hypomobility or hypermobility (p<.01). Postoperative ROM averaged over all study subjects provides incomplete information about the prosthesis performance - it does not tell us how many implanted segments achieve physiological mobility and how many end up with hypomobility or hypermobility. We conclude that the proportion of index levels achieving postCDA motions in the physiological mobility range (5°-16°) is a more useful outcome measure for future clinical trials.

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.

BACKGROUND CONTEXT: Lumbar discectomy is largely successful surgical procedure; however, reherniation rates in patients with large annular defects are as high as 27%. The expense associated with a revision surgery places significant burden on the healthcare system. PURPOSE: To compare the direct health care costs through 5 years follow-up of conventional discectomy (Control) with those of discectomy supplemented by an adjunctive annular closure device (ACD) in high-risk patients with large annular defects. STUDY DESIGN: This was a cost-effectiveness study. METHODS: All-cause index level reoperations were reviewed from a multicenter, randomized controlled superiority trial that allocated 554 high-risk discectomy patients with large annular defects to either control or ACD. Medicare and private insurer (Humana) direct costs were derived from a commercially available payer database to estimate costs in the US healthcare system, including those associated with facility, surgeon, imaging, follow-up visits, physical therapy, and injections. A 50: 50 split between Medicare and commercial insurers was assumed for the base case analysis. The analysis was also performed on a 80: 20 commercial: Medicare payer basis. For the base case scenario, a 2-year time horizon and outpatient cost setting was established for the index procedure. Repeat discectomy was assumed to be performed on a 60: 40 outpatient-to-inpatient basis. Complications requiring surgery, revisions, and/or fusion were assumed to be managed in the inpatient setting. Total costs of reoperation and per-patient costs of reoperation were compared between groups for both forms of insurers. One author received consulting fees of <$50,000 for the completion of this study, and the other eight authors did not have any financial associations with the current work. Funding for this study was provided by Intrinsic Therapeutics, but all analyses, interpretation, and writing were performed independently by the authors. RESULTS: At two years follow-up, use of the ACD reduced the rate of symptomatic reherniations in a large defect population to 13% compared with 25% in the control group (p<.001). This reduction in symptomatic reherniations in the ACD group translated to a savings of $2,802 per patient in direct health care costs compared with Control at 2 years and $5,315 per patient by 5 years based on 50% private and 50% public (Medicare) payer split. Under the scenario of 80: 20 private: public insurance reimbursement, the estimated direct cost savings were $3,215 and $6,099 per patient at 2- and 5-years postoperatively, respectively, with the use of the ACD. CONCLUSIONS: Symptomatic reherniation and reoperation rates were nearly double among control patients compared with ACD-treated patients, which translated to markedly greater per-patient health-care costs in the control group, where the ACD was not used. (C) 2019 Published by Elsevier Inc.

The evidence-based literature offers little support for surgical treatment of spine patients with workers' compensation claims. Low back pain patients treated surgically in the SPORT study, for example, were generally found to have significantly greater improvement after two years than nonoperative patients, while workers' compensation claimants saw no added benefit with surgery. Cervical disc arthroplasty (CDA) for workers' compensation patients, however, has been reported to provide significant improvement in pain and disability outcomes, and significantly earlier return to work than anterior cervical discectomy and fusion in recent IDE studies.

BACKGROUND CONTEXT: The Prestige LP Cervical Disc Prosthesis consists of two components which articulate through a proprietary ball and trough design. Titanium Ceramic Composite material provides excellent wear and imaging performance. Ball and trough designed to allow for physiological motion in the cervical spine (e.g. flexion/extension and AP translation, lateral bending, and unconstrained axial rotation.). Dual stabilization rails engage the vertebral end-plates to provide immediate fixation and torsional stability. A clinically proven titanium spray provides long-term fixation through bone integration. Low anterior profile allows for multi-level placement.

BACKGROUND CONTEXT: A considerable subset of patients demonstrate symptomatic multiple level lumbar discogenic disease. The rationale behind arthroplasty in preserving adjacent level segments becomes more important in this group of patients given the larger cantilever forces at play. In efforts to preserve motion and limit force concentrations at the remaining lumbar segments hybrid disc arthroplasty is gaining momentum as a new treatment modality.To our knowledge there are no clinical studies which evaluate the outcomes of patients with hybrid disc arthroplasty. The present study evaluates our subset of patients through their patient perceived outcomes, return to sport and their return to work.

BACKGROUND CONTEXT: The FDA has recently approved total disc replacement in the lumbar spine with the Charité Artificial Disc. Although the majority of procedures result in a satisfactory result, a small percentage of cases are unsuccessful and require revision. We analyzed 15 consecutive cases referred to the first author for revision surgery.

BACKGROUND CONTEXT: Transforaminal posterior lumbar interbody fusion (TLIF) generally involves the use of autograft with various types of cages composed of either metal or allograft bone. Allograft with recombinant human bone morphogenetic protein-2 (rhBMP-2) has been reported to be used for TLIF of late. Bioresorbable interbody spacers have emerged as an alternative to both autograft and cadaver allograft with the attendant advantage of obviating donor site morbidity and allograft-associated complications. The bioresorbable implant provides immediate motion segment stability, radiolucency, and time dependant stress transfer to host bone with the graft breakdown products not being mutagenic or immunogenic. Due to the morbidity associated with large muscle stripping incisions, autograft donor sites, and posterolateral transverse process fusions, minimally invasive techniques with new technologies such as the combination of bioresorbable polymers and rhBMP-2 have been developed and used for minimal access transforaminal interbody arthrodesis.

BACKGROUND CONTEXT: Anterior cervical discectomy and interbody fusion (ACDF) is an accepted treatment option for degenerative spondylosis/instability of the cervical spine that is unresponsive to conservative treatment. An animal model study, reported in 1998, concluded that the use of titanium cervical interbody cages with and without the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) resulted in accelerated arthrodesis. Successful cervical fusions have been reported at 6 months in humans using an allograft ring filled with rhBMP-2. Bioresorbable interbody spacers have emerged as an alternative to both autograft and cadaver allograft with the attendant advantage of obviating donor site morbidity and allograft-associated complications. The bioresorbable implant provides immediate motion segment stability, radiolucency, and time dependant stress transfer to host bone with the graft breakdown products not being mutagenic or immunogenic.

Introduction: Although 70-80% of AIDS patients exhibit neurological disorders, a reliable neuropathological diagnosis is a prerequisite for a specifically selected treatment. However, modern imaging techniques do not permit a definitive diagnosis. In order to clarify the efficacy of stereotactic techniques and to understand the neurological disorders in AIDS, a series of imaging-guided stereotactic brain biopsies in 150 neurologically symptomatic patients with AIDS was studied. Method: Of the patients 148 were men and two were women with the mean age 42.06 + 7.2. The indications for the biopsy were determined not only by having radiologically detectable lesions with no regression tendency under antitoxoplasmosis therapy but also by presenting positive neurological symptoms. Surgery was performed under local and general anesthesia in the Cedars Sinai Hospital through Cosman-Roberts-Wells stereotactic system with minor modifications. Results: The common neurological symptoms included headache, hemiparesthesis, mental disorder, and speech or gait disorders. The common locations of lesions...