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Background: Short term results of the change of center of rotation (COR) after Bryan cervical disc replacement (CDR) have been reported. However, there is a lack of long-term studies focusing on the COR and its influences on facet joint degeneration., Objective: To evaluate the long-term clinical and radiographic results of Bryan CDR, and to explore the influence of deviated COR on facet joint degeneration at index level., Methods: It is a retrospective follow up study conducted in China. Eighty-three consecutive patients who received single-level Bryan CDR were retrospectively reviewed. Clinical evaluation included Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and Odom's scale. Radiographic evaluation underwent before surgery, at early follow-up (3 months) and last follow-up (10 years). The radiographic parameters included range of motion (ROM), location of COR presented by the coordinates (COR-x, COR-y), and facet joint degeneration score. Correlation analysis was conducted between changes of COR and facet joint degeneration score., Results: Fifty-nine patients were included, with an average age of 44.6 ± 7.4 years. The mean follow-up time was 135.7 ± 12.4 (120-155) months. JOA score, NDI and Odom's scale showed significant improvements at last follow-up. The ROM was well preserved through follow-up. 33 patients (55.9%) showed deterioration of facet joint degeneration at index level. The increment of facet joint degeneration score at index level was strongly correlated with the change of COR-x (r = 0.758, P < 0.001), and weakly correlated with the change of COR-y (r=-0.473, P < 0.001). The deviation of COR was significantly greater in Group Degeneration than that in Group Non-degeneration (14.8 ± 10.5% vs. -2.6 ± 8.1% for COR-x, and - 6.4 ± 7.5% vs. 0.8 ± 8.3% for COR-y)., Conclusions: Bryan CDR with minimum of 10-year follow-up achieved favorable clinical outcome and good maintenance of ROM. Deviated COR could be an important risk factor for facet joint degeneration., (© 2024. The Author(s).)

Objective: This study aimed to develop and validate a machine learning (ML) model to predict high-grade heterotopic ossification (HO) following Anterior cervical disc replacement (ACDR)., Methods: Retrospective review of prospectively collected data of patients undergoing ACDR or hybrid surgery (HS) at a quaternary referral medical center was performed. Patients diagnosed as C3-7 single- or multi-level cervical disc degeneration disease with > 2 years of follow-up and complete pre- and postoperative radiological imaging were included. An ML-based algorithm was developed to predict high grade HO based on perioperative demographic, clinical, and radiographic parameters. Furthermore, model performance was evaluated according to discrimination and overall performance., Results: In total, 339 ACDR segments were included (61.65% female, mean age 45.65 ± 8.03 years). Over 45.65 ± 8.03 months of follow-up, 48 (14.16%) segments developed high grade HO. The model demonstrated good discrimination and overall performance according to precision (High grade HO: 0.71 ± 0.01, none-low grade HO: 0.85 ± 0.02), recall (High grade HO: 0.68 ± 0.03, none-low grade HO: 0.87 ± 0.01), F1-score (High grade HO: 0.69 ± 0.02, none-low grade HO: 0.86 ± 0.01), and AUC (0.78 ± 0.08), with lower prosthesis‑endplate depth ratio, higher height change, male, and lower postoperative-shell ROM identified as the most important predictive features., Conclusion: Through an ML approach, the model identified risk factors and predicted development of high grade HO following ACDR with good discrimination and overall performance. By addressing the shortcomings of traditional statistics and adopting a new logical approach, ML techniques can support discovery, clinical decision-making, and intraoperative techniques better., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Study Design: Retrospective cohort study., Objective: To investigate the impact of age on the incidence of vascular complications in patients undergoing anterior lumbar approach surgery., Background: Anterior approach lumbar spinal surgery may facilitate the use of intervertebral devices with larger endplate coverage and increased lordosis. Despite the advantages of this approach, risks related to vascular injury in older patients have been described in the literature., Patients and Methods: In total, 751 consecutive patients with degenerative spinal pathology who underwent stand-alone anterior lumbar interbody fusion (ALIF), ALIF combined with posterior fusion and/or instrumentation (360), total disc replacement, or hybrid procedures (ALIF and total disc replacement) were included. Data collected included general patient descriptive data, surgery details, intraoperative vascular injury, and postoperative vascular complications (deep vein thrombosis and/or pulmonary embolism). Rates of vascular complications were compared across age groups. In addition, the mean age of patients was compared between those with versus without vascular complications., Results: Overall mean age was 50.4 years (range: 20-83 yr). The mean estimated blood loss was 91.3 mL (range: 10-2800 mL). A total of 15 patients, 2.0%, had vascular complications. There were 10 cases (1.3%) of intraoperative injury to iliac arteries or iliolumbar veins (mean blood loss was 721 mL, and all were repaired intraoperatively). Postoperatively, 6 patients (0.8%) developed deep vein thrombosis and/or pulmonary embolism (one patient had both). With respect to age, there were no significant differences in rates of intraoperative, postoperative, or combined vascular complication rates across the age group ( P > 0.38). In addition, there were no statistically significant differences in the mean ages of patients with versus those without vascular complications ( P > 0.17)., Conclusion: Overall incidence of vascular complications was 2.0%. No relationship between vascular complications and age was demonstrated. These data suggest that increased age may not necessarily be an absolute contraindication for anterior lumbar approach surgery., Level of Evidence: Level III., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective database review., Objective: The aim of this study was to analyze revisions of CDAs reported to the MAUDE database., Summary of Background Data: Cervical disk arthroplasty (CDA) has emerged as a motion-preserving alternative to anterior cervical discectomy and fusion (ACDF) for degenerative cervical disease, demonstrating comparable outcomes. Despite the availability of variable CDA designs, there is limited data on the specific complications of individual CDAs. The Drug Administration's Manufacturer and User Facility Device Experience (MAUDE) database has been used to systematically report complications associated with CDAs. However, data on specific reasons for CDA revision remains scarce. The purpose of this study is to compare common complications associated with revision for different CDAs., Methods: The MAUDE database was queried from January 2005 to September 2023, including all nine FDA-approved CDAs. The full-text reports of each complication were categorized based on whether revision surgery was performed, the complications and the type of CDA collected and compared., Results: A total of 678 revisions for nine CDAs were reported: Mobi-C (239), M6 (167), Prodisc-C (88), Prestige (60), PCM (44), Bryan (35), Secure (23), Simplify (21), and Discover (1). The top three complications associated with revision were migration (23.5%), neck pain (15.5%), and heterotopic ossification (6.6%). The most common complications per device were migration for Mobi-C (26.4%), Prodisc-C (21.3%), Prestige (24.6%), PCM (84.1%), Bryan (48.6%), Secure (30.4%), and Discover (100%). For M6, the most common complications associated with revision surgery were osteolysis (18.6%) and neck pain (18.6%), while neck pain (23.8%) was the most common for the Simplify., Conclusions: The MAUDE database highlights complications related to CDA revision in which the primary complications consistently include implant migration, neck pain, and heterotopic ossification, varying in their rerelvance depending on the CDA., Level of Evidence: Level II., Competing Interests: C.A. is a consultant on the advisory board for Camber Spine Tech; a consultant for Centinel Spine Inc.; is in the advisory board, and has an ownership interest in Orthobond Corporation and Surgalign. D.R.L. is a consultant and on the advisory board for Choice Spine; is a consultant for Depuy Synthes; has ownership interest from Woven Orthopedic Technologies, Vestia Ventures MiRus Investment LLC, HS2 LLC, and ISPH II LLC; has research support from Medtronic Sofamor Danek USA Inc.; has royalties from Nuvasive Inc.; is on the advisory board and has ownership interest from Remedy Logic; is a consultant and has royalties from Stryker; is a consultant and has ownership interest from Viseon Inc. The remaining authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Systematic review and meta-analysis., Objective: Describe the impact of endplate coverage on HO in cervical disc replacement (CDR)., Summary of Background Data: CDR is a motion-sparing alternative to anterior cervical discectomy and fusion. However, the high prevalence of heterotopic ossification threatens to diminish range of motion and limit this benefit associated with CDR., Materials and Methods: A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. EMBASE and PubMed databases were queried. Results were deduplicated and screened. Relevant studies were included. All metrics that were reported in ≥3 studies were aggregated for analysis. SPSS was used to perform the meta-analysis., Results: A total of 10 studies were included in the systematic review. Endplate coverage was assessed using a wide variety of measurements, including anteroposterior implant depth (ID), endplate depth (ED), exposed endplate depth (EED), implant depth to endplate depth ratio (ID:ED), EED to ED ratio (EED:ED), implant width (IW) to endplate width (EW) ratio (IW:EW), and the implant area (IA) to endplate area (EA) ratio (IA:EA). No evidence has linked ID (three studies) to HO. Mixed evidence has linked ID:ED (3/5) and IW:ED (1/2) to HO. All available evidence has linked ED (2), EED (4), EED:ED (2), and IA:EA (1) to HO. In our meta-analysis, ID was not found to be a significant risk factor for HO. However, EED and ID:ED were found to be significant risk factors for HO formation., Conclusions: Exposed endplate, especially as assessed by EED and ID:ED, is a significant risk factor for HO. Surgeons should focus on preoperative planning and intraoperative implant selection to maximize endplate coverage. While optimizing technique and implant selection is crucial, improved implant design may also be necessary to ensure that appropriate implant-endplate footprint matching is possible across the anatomic spectrum., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: Cervical disc arthroplasty (CDA) is widely employed for patients diagnosed with cervical degenerative disc disease (CDDD). Postoperative bone loss (BL) represents a radiological alteration that is a relatively novel consideration in the realm of CDA. This study endeavors to examine the risk factors associated with BL following CDA, aiming to elucidate the underlying mechanisms and the impact of BL on surgical outcomes., Methods: A retrospective study was undertaken, encompassing consecutive patients subjected to one-level CDA, two-level CDA, or two-level hybrid surgery (HS) for the treatment of CDDD at our institution. Patient demographic and perioperative data were systematically recorded. Radiological images obtained preoperatively, at 1-week post-operation, and during the last follow-up were collected and evaluated, following with statistical analyses., Results: A total of 295 patients and 351 arthroplasty segments were involved in this study. Univariate logistic regressions indicated that age ≥ 45 years and two-level HS was associated with lower risk of BL; and a greater ΔDA (change of disc angle before and after surgery) was correlated with an increased risk of BL. Multivariate logistic regression determined that two-level HS and greater ΔDA were independent preventative and risk factors for BL, respectively. Further analysis revealed that severe BL significantly elevated the risk of implant subsidence compared to non-BL and mild BL., Conclusions: This study posited bone remodeling and micromotion as potential underlying mechanisms of BL. Subsequent research endeavors should delve into the divergent mechanisms and progression observed between lower- and higher-grade BL, aiming to prevent potential adverse outcomes associated with severe BL., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background Context: Clinical trials have demonstrated that cervical disc arthroplasty (CDA) is an effective and safe alternative treatment to anterior cervical discectomy and fusion (ACDF) for cervical degenerative disc disease in the appropriately indicated patient population. Various devices for CDA exist, differing in the level of device constraint., Purpose: To investigate outcomes following Anterior Cervical Discectomy and Fusion (ACDF) versus CDA stratified based on the level of device constraint: Constrained, Semiconstrained, and Unconstrained., Study Design: Systematic review and network meta-analysis., Patient Sample: A total of 2,932 CDA patients (979 Constrained, 1,214 Semiconstrained, 739 Unconstrained) and 2,601 ACDF patients from 41 studies that compared outcomes of patients undergoing CDA or ACDF at a single level at a minimum of 2 years follow-up., Outcome Measures: Outcomes of interest included the development of adjacent segment degeneration (ASD), index and adjacent segment reoperation rates, range of motion (ROM), high-grade heterotopic ossification (HO, McAfee Grades 3/4), and patient-reported outcomes (NDI/VAS)., Methods: CDA devices were grouped based on the degrees of freedom (DoF) allowed by the device, as either Constrained (3 DoF), Semiconstrained (4 or 5 DoF), or Unconstrained (6 DoF). A random effects network meta-analysis was conducted using standardized mean differences (SMD) and log relative risk (RR) were used to analyze continuous and categorical data, respectively., Results: Semiconstrained (p=.03) and Unconstrained CDA (p=.01) demonstrated a significantly lower risk for ASD than ACDF. All levels of CDA constraint demonstrated a significantly lower risk for subsequent adjacent segment surgery than ACDF (p<.001). Semiconstrained CDA also demonstrated a significantly lower risk for index level reoperation than both ACDF and Constrained CDA (p<.001). Unconstrained devices retained significantly greater ROM than both Constrained and Semiconstrained CDA (p<.001). As expected, all levels of device constraint retained significantly greater ROM than ACDF (p<.001). Constrained and Unconstrained devices both demonstrated significantly lower levels of disability on NDI than ACDF (p=.02). All levels of device constraint demonstrated significantly less neck pain than ACDF (p<.05), while Unconstrained CDA had significantly less arm pain than ACDF (p=.02) at final follow-up greater than 2 years., Conclusion: CDA, particularly the unconstrained and semiconstrained designs, appears to be more effective than ACDF in reducing the risk of adjacent segment degeneration and the need for further surgeries, while also allowing for greater range of motion and better patient-reported outcomes. Less constrained CDA conferred a lower risk for index level reoperation, while also retaining more range of motion than more constrained devices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: This study examined clinical outcomes associated with 3 types of noncontiguous cervical surgeries - anterior cervical discectomy and fusion (ACDF), cervical disc arthroplasty (CDA), and hybrid cervical surgery (HCS) - to improve surgeon decision-making., Methods: A systematic review was performed using PubMed, CINAHL, MEDLINE, and Web of Science from database inception until June 6th, 2023. Inclusion criteria were studies that reported any type of clinical outcome, examined noncontiguous ACDF, noncontiguous CDA, and/or noncontiguous HCS., Results: Ten articles out of 523 articles initially retrieved were included. Patients (n = 388) had a mean age of 52 ± 5.1 years and a mean follow up time of 33 ± 6.0 months. Overall, 119 patients underwent non-contiguous HCS, 65 underwent non-contiguous CDA, and 204 underwent non-contiguous ACDF. There appears to be no clinically meaningful difference in Neck Disability Index (NDI) score, Japanese Orthopedic Association (JOA) score, and improvement in pain based on surgery type. There was a total of 83 complications (21% of cases) with non-contiguous ACDF having a higher absolute rate of dysphagia (20%) as compared to non-contiguous HCS (6.7%) or non-contiguous CDA (6.2%). Non-contiguous ACDF had a higher absolute rate of adjacent segment degeneration (ASD) as a reported complication (6.4%) as compared to non-contiguous HCS (1.7%) and non-contiguous CDA (0.0%)., Conclusions: There may be no clinically meaningful difference in many clinical outcomes for different non-contiguous surgical interventions for non-contiguous cervical degenerative disc disease (CDDD). However, complication rates, such as dysphagia and ASD, appear higher for non-contiguous ACDF as compared to non-contiguous CDA or HCS., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: Cervical total disc replacement (cTDR) has been established as an alternative treatment for degenerative cervical radiculopathy and myelopathy. While the rate of complications for cTDR is reasonably low, recent studies have focused on bone loss after cTDR. The purpose of this work is to develop a clinical management plan for cTDR patients with evidence of bone loss. To guide our recommendations, we undertook a review of the literature and aimed to determine: (1) how bone loss was identified/imaged, (2) whether pre- or intraoperative assessments of infection or histology were performed, and (3) what decision-making and revision strategies were employed., Methods: We performed a search of the literature according to PRISMA guidelines. Included studies reported the clinical performance of cTDR and identified instances of cervical bone loss., Results: Eleven case studies and 20 cohort studies were reviewed, representing 2073 patients with 821 reported cases of bone loss. Bone loss was typically identified on radiographs during routine follow-up or by computed tomography (CT) for patients presenting with symptoms. Assessments of infection as well as histological and/or explant assessment were sporadically reported. Across all reviewed studies, multiple mechanisms of bone loss were suspected, and severity and progression varied greatly. Many patients were reportedly asymptomatic, but others experienced symptoms like progressive pain and paresthesia., Conclusion: Our findings demonstrate a critical gap in the literature regarding the optimal management of patients with bone loss following cTDR, and treatment recommendations based on our review are impractical given the limited amount and quality evidence available. However, based on the authors' extensive clinical experience, close follow-up of specific radiographic observations and serial radiographs to assess the progression/severity of bone loss and implant changes are recommended. CT findings can be used for clinical decision-making and further follow-up care. The pattern and rate of progression of bone loss, in concert with patient symptomatology, should determine whether non-operative or surgical intervention is indicated. Future studies involving implant retrieval, histopathological, and microbiological analysis for patients undergoing cTDR revision for bone loss are needed., (© 2024. The Author(s).)

Background Context: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are commonly performed operations to address cervical radiculopathy and myelopathy. Trends in utilization and revision surgery rates warrant investigation., Purpose: To explore the epidemiology, postoperative complications, and reoperation rates of ACDF and CDA., Design: Retrospective cohort study., Patient Sample: A total of 433,660 patients who underwent ACDF or CDA between 2011 and 2021 were included in this study., Outcome Measures: The following data were observed for all cases: patient demographics, complications, and revisions., Methods: The PearlDiver database was queried to identify patients who underwent ACDF and CDA between 2011 and 2021. Epidemiological analyses were performed to examine trends in cervical procedure utilization by age group and year. After matching by age, sex, Charlson Comorbidity Index (CCI), levels of operation, and reason for surgery, the early postoperative (2-week), short-term (2-year), and long-term (5-year) complications of both cervical procedures were examined., Results: In total, 404,195 ACDF and 29,465 CDA patients were included. ACDF utilization rose by 25.25% between 2011 and 2014 while CDA utilization rose by 654.24% between 2011-2019 followed by relative plateauing in both procedures. Mann-Kendall trend test confirmed a significant but small rise in ACDF and large rise in CDA procedures from 2011 to 2021 (p<.001). After matching, ACDF and CDA had an overall complication rate of 12.20% and 8.77%, respectively, with the most common complications being subsequent anterior revision (4.96% and 3.35%) and dysphagia (3.70% and 2.98%). The ACDF cohort, especially multilevel ACDF patients, generally had more complications and higher revision rates than the CDA cohort (p<.05)., Conclusions: While ACDF utilization has plateaued since 2014, CDA rates have risen by a staggering 654.24% over the past decade. ACDF and CDA complication and revision rates were relatively low in comparison to previously published values, with significantly lower rates in CDA. Although a lack of radiographic data in this study limits its power to recommend either procedure for individual patients with cervical radiculopathy or myelopathy, CDA may be associated with minor improvement in the complication and revision profile., Competing Interests: Declaration of competing interest MS, KP, MB, MD, JG, JL, and CLM have nothing to declare. BGD reports the following: receives consulting fees from Clariance and SpineVision. AHD discloses the following, receives royalties from Spineart and Stryker, consulting fees from Medtronic, research support from Alphatec, Medtronic, and Orthofix, and Fellowship support from Medtronic., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Study Design: A retrospective study., Objective: In this study, a cervical degenerative quantitative scoring system was used to identify the risk factors for disc height loss after cervical disc replacement (CDR) and to verify their accuracy., Background: Disc height loss after CDR is drawing much attention. Preoperative cervical degeneration has been proven related to postoperative disc height loss but lacked quantitative verification., Patients and Methods: A total of 160 patients who underwent CDR with the Prestige-LP disc at our hospital between January 2011 and December 2016 were retrospectively reviewed. Disc height loss was defined as a reduction of more than 2 mm from postoperative to the final follow-up. A quantitative scoring system was used to evaluate preoperative degeneration on radiographs. Multivariate logistic regression was applied to determine predictive factors and calculate the logistic regression formula. Moreover, receiver operating characteristic curve analysis was conducted to obtain the optimal cutoff value and the area under the receiver operating characteristic curve [areas under the curve (AUC)]., Results: Study subjects had a mean age of 43.51 ± 8.51 years, with a mean follow-up time of 60.14 ± 12.75 months. The overall incidence rate of disc height loss was 65.62%. Multivariate logistic regression analysis showed that endplate sclerosis ( P = 0.000) and low preoperative disc height ( P = 0.000) were independent risk factors for postoperative disc height loss. In addition, the calculated optimal cutoff point was 1 point of endplate sclerosis (AUC = 0.768) and 4.5 mm of preoperative disc height (AUC = 0.795). The regression formula established by multivariate logistic regression analysis was composed of preoperative disc height (odds ratio: 2.995, P = 0.000) and endplate sclerosis (odds ratio: 18.131, P = 0.000), with an AUC of 0.879., Conclusions: Our findings suggest that a comprehensive preoperative assessment is essential when patients with apparent endplate sclerosis and low preoperative disc height are being considered for CDR., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Study Design: Retrospective cohort study., Objective: To compare the demographics, perioperative variables, and complication rates following cervical disk replacement (CDR) among patients with and without metabolic syndrome (MetS)., Summary of Background Data: The prevalence of MetS-involving concurrent obesity, insulin resistance, hypertension, and hyperlipidemia-has increased in the United States over the last 2 decades. Little is known about the impact of MetS on early postoperative outcomes and complications following CDR., Methods: The 2005-2020 National Surgical Quality Improvement Program was queried for patients who underwent primary 1- or 2-level CDR. Patients with and without MetS were divided into 2 cohorts. MetS was defined, according to other National Surgical Quality Improvement Program studies, as concurrent diabetes mellitus, hypertension requiring medication, and body mass index ≥30 kg/m 2 . Rates of 30-day readmission, reoperation, complications, length of hospital stay, and discharge disposition were compared using χ 2 and Fisher exact tests. One to 2 propensity-matching was performed, matching for demographics, comorbidities, and number of operative levels., Results: A total of 5395 patients were included for unmatched analysis. Two hundred thirty-six had MetS, and 5159 did not. The MetS cohort had greater rates of 30-day readmission (2.5% vs. 0.9%; P =0.023), morbidity (2.5% vs. 0.9%; P =0.032), nonhome discharges (3% vs. 0.6%; P =0.002), and longer hospital stays (1.35±4.04 vs. 1±1.48 days; P =0.029). After propensity-matching, 699 patients were included. All differences reported above lost significance ( P >0.05) except for 30-day morbidity (superficial wound infections), which remained higher for the MetS cohort (2.5% vs. 0.4%, P =0.02)., Conclusions: We identified MetS as an independent predictor of 30-day morbidity in the form of superficial wound infections following single-level CDR. Although MetS patients experienced greater rates of 30-day readmission, nonhome discharge, and longer lengths of stay, MetS did not independently predict these outcomes after controlling for baseline differences in patient characteristics., Level of Evidence: Level III., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: This was a retrospective study with prospective patient contact attempted to collect current data., Objective: The purpose was to investigate the incidence and reasons for lumbar total disk replacement (TDR) removal or revision., Summary of Background Data: A concern regarding lumbar TDR was safety, particularly the need for device removal or revision. This may be particularly important considering removal/revision requires repeat anterior exposure with an increased risk of vascular injury., Methods: Data were collected for a series of 2141 lumbar TDR patients, beginning with the first case experience in 2000. The mean follow-up was 78.6 months. For each case of device removal/revision, the reason, duration from index surgery, and procedure performed were recorded., Results: Of 2141 patients, 27 (1.26%) underwent TDR removal or revision. Device removal was performed in 24 patients (1.12%), while three patients underwent revision (0.14%). Of the 24 removals, 12 were due to migration and/or loosening, three developed problems post-trauma, two developed lymphocytic reaction to device materials, two had ongoing pain, and there was one case of each: TDR was too large, vertebral body fracture (osteoporosis), lytic lesion, device subsidence and facet arthrosis, and infection seeded from a chest infection 146 months post-TDR. The three revisions were for Core repositioning (technique error), device repositioning after displacement, and core replacement due to wear/failure. With respect to timing, 37.0% of removals/revisions occurred within one-month postimplantation. Of note, 40.7% of removals/revisions occurred in the first 25 TDR cases performed by individual surgeons. There was one significant vascular complication occurring in a patient whose TDR was removed due to trauma. This was also the only patient among 258 with ≥15-year follow-up who underwent removal/revision., Conclusion: In this large consecutive series, 1.26% of TDRs were removed/revised. The low rate over a 20 year period supports the safety of these devices., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background Context: Anterior cervical disc replacement (ACDR) and minimally invasive posterior cervical foraminotomy (MI-PCF) have emerged as two increasingly popular alternatives to anterior cervical discectomy and fusion (ACDF) for the management of cervical radiculopathy. Both techniques provide advantages of segmental motion preservation and lower rates of adjacent segment degeneration (ASD) compared to ACDF., Purpose: The purpose of this study was to analyze the clinical and functional outcomes of patients undergoing ACDR or MI-PCF for the treatment of unilateral cervical radiculopathy., Study Design/setting: Retrospective Cohort Review., Patient Sample: A total of 152 patients were included (86 ACDR and 66 MI-PCF)., Outcome Measures: (1) Patient demographics; (2) perioperative data; (3) rates of complications and revisions; (5) visual analogue scale (VAS) and Neck Disability Index (NDI) scores., Methods: A retrospective cohort review was performed to identify all patients at a single institution between 2012-2020 who underwent 1- or 2- level ACDR or MI-PCF from C3-C7 with a minimum follow-up of 24 months. Patient demographics, perioperative data, postoperative complications, and revisions were analyzed. Patient reported outcome measures including VAS and NDI scores were compared., Results: The ACDR group had a significantly greater mean operative time (99.8 minutes vs 79.2 minutes, p<.001), but comparable estimated blood loss and length of stay following surgical intervention (p=.899). The overall complication rate was significantly greater in the ACDR group than the MI-PCF group (24.4% vs 6.2%; p=.003) but was largely driven by approach-related dysphagia in 20.9% of ACDR patients. The MI-PCF group had significantly greater revision rates (13.6% vs 1.2%; p=.002) with an average time to revision of 20.7 months in the MI-PCF group compared to 40.3 months in the ACDR group. The ACDR cohort had significantly greater improvements in NDI scores at the final follow-up (25.0 vs 21.3, p<.001)., Conclusion: Our results suggest that ACDR offer clinically relevant advantages over MI-PCF in terms of long-term revision rates despite an increased approach-related risk of transient postoperative dysphagia. Additionally, patients in the ACDR cohort achieved greater mean improvements in NDI scores but these results may have limited clinical significance due to inability to reach minimally clinically important difference (MCID) thresholds., Competing Interests: Declaration of competing interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: This retrospective study was designed to evaluate the incidence and predisposing factors of heterotopic ossification (HO) after cervical disc arthroplasty (CDA) with a specific implant at 1 and 2 levels, and to investigate the biomechanical effects related to HO. The study goal was to identify ways to reduce the likelihood of HO formation after surgery., Methods: The study included patients who underwent only 1- or 2-level CDA with the Baguera C disc between November 2014 and December 2021 at a single medical center. All patients were operated on by the same neurosurgeon. The surgical indication included 1-level or 2-level disc herniation between C3 and C7 with radiculopathy, myelopathy, or both, with minimal spondylosis. The various factors were assessed by evaluating plain radiographs and cervical CT scans. The presence of HO was evaluated at different intervals postsurgery, and HO severity was graded using the McAfee classification., Results: Of 107 patients who underwent CDA, 47 (43.9%) had HO at 63 of 171 levels (36.8%). Most cases with HO were grade 1, and no grade 4 was observed. Statistically significant risk factors for HO were the length of endplate coverage ratio and inferior anterior residual exposed endplate (AREE); sex, age, implant height and width, shell angle, and pre- and postoperative functional spinal unit (FSU) angle were not significant. More AREE and greater kyphotic postoperative FSU angle in the flexion position were significant factors differentiating HO grades 0 and 1 from grades 2 and 3. Furthermore, the non-HO group showed a trend of higher range of motion at any postoperative time compared to the HO group, especially at 1 month after surgery., Conclusions: The HO incidence after CDA was correlated with the residual length of endplate coverage and inferior AREE. Additionally, the AREE and kyphotic postoperative FSU angle in the flexion position were associated with HO grade progression. Patients with HO also showed a trend of lower range of motion at 1 month after surgery. Using an adequately sized implant and encouraging neck motion may help prevent HO development and progression.

Introduction: A recent study reported a 34% mid-term revision rate after M6-C™ cervical total disc replacement (CTDR) for wear-related osteolysis. Here, we aim to investigate the prevalence, risk factors, and radiographic characteristics of periprosthetic bony changes and implant failure of the M6-C™ artificial disc., Methods: We retrospectively analysed radiographic (conventional X-ray, CT scan) and clinical outcomes (EQ-5D-5L, Neck Disability Index (NDI), and Visual Analog Scale (VAS) for neck and arm pain) data collected during routine follow-up of patients who underwent CTDR with the M6-C™ between 2011 and 2015., Results: In total, 85 patients underwent CTDR with the M6-C™. Follow-up data were available for 43 patients (54% female, mean age 44 years) with 50 implants and a mean follow-up of 8.1 years (6.5-11 years). Implant failure with the presence of severe osteolysis was identified in 5 (12%) patients who were all male (p = 0.016) and implanted at the C5/6 level (p = 0.11). All failed implants required revision surgery. The overall prevalence of osteolysis was 44% (22/50 implants) and 34% (17/50 implants) for significant heterotopic ossification. Patients with high-grade osteolysis showed higher VAS arm pain (p = 0.05) and lower EQ-5D-VAS health VAS (p = 0.03)., Conclusion: We report a lower reoperation rate for failed M6-C™ implants than previously published, but confirmed that osteolysis and heterotopic ossification are common following CTDR with the M6-C™ and may be asymptomatic. Therefore, we strongly recommend ongoing clinical and radiographic monitoring after CTDR with the M6-C™, particularly for male patients implanted at the C5/6 level., (© 2024. The Author(s).)

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, FDA-approved 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., Competing Interests: Declaration of competing interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To characterize the change of adjacent segment degeneration (ASD) after cervical total disc replacement (CTDR) with more than 12-year follow-up, and identify the risk factors for ASD., Method: This process included 75 patients underwent CTDR from February 2004 to December 2012, with the follow-up of 151.9 ± 36.0 (m). The artificial disc included ProDisc-C, Prestige-LP and Mobi-C. ASD was followed up at 1 week, 6 months, 1 year, 2 years, 5 years, 10 years after CTDR and at the endpoint of June 2022. The radiographic measurements were cervical mobility, intervertebral disc height (IDH), cervical lordosis and balance status. The complications were implant migration, subsidence and heterotopic ossification (HO)., Results: Cervical mobility in adjacent segments, IDH and lordosis showed no statistical differences between ASD and NASD group. Balance status, subsidence and migration showed no relationship with ASD. Postoperative ASD increased at 6 m and especially between 6 m to 2y. There was no difference between the incidence of upper ASD and lower ASD all the time and few ASD-related reoperation. The majority of adjacent segments were C4/5 (33.6%) and C6/7 (34.2%), and ASD of C5/6 had the highest incidence (61.5%). Cox regression showed ASD was not related to the types of prosthesis or operated numbers. Generalized estimating equations (GEE) analysis showed severe HO had a higher (2.68 times) probability to suffer from ASD., Conclusions: After over 12-year follow-up of CTDR, the occurrence of ASD and HO had temporal synchronization. ASD was not merely a natural progression but with the pathological process such as HO., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background Context: Anterior cervical discectomy and fusion (ACDF) is the leading surgical treatment for cervical radiculopathy. However, ACDF surgery has been suggested for to accelerate the degeneration of the adjacent cervical discs, which causes so-called adjacent segment disease (ASD). Over the past 2 decades, total disc replacement (TDR)/cervical disc arthroplasty (CDA) has become an increasingly common method for treating degenerative cervical diseases. The rationale is that a synthetic disc prosthesis may preserve motion at the operated level, which is expected to lead to reduced stress on the other cervical levels and thus decrease the risk of developing ASD. However, since the method was first introduced in the early 2000s, the long-term outcome after it is still not completely understood., Purpose: Our goal was to compare the long-term outcomes of TDR and ACDF procedures., Study Design: Retrospective case-control study., Patient Sample: All patients who underwent TDR due to degenerative cervical disease at Helsinki University Hospital between 2006 and 2012 (38 patients) and matched control patients who underwent ACDF during this period (76 patients) for degenerative disc disease., Outcome Measures: The primary outcome measure was the rate of reoperations and further cervical surgeries. Secondary outcome measures included neck symptoms (Neck Disability Index, or NDI), health-related quality of life (EQ-5D-3L), satisfaction with the surgery, radiological outcomes, and employment status., Methods: The medical records of all patients who underwent TDR due to degenerative cervical disease at Helsinki University Hospital between 2006 and 2012 and those of the matched control patients were analyzed retrospectively. Questionnaires were sent to all available patients at the end of the follow-up (median 14 years) to evaluate their employment status, levels of satisfaction with the surgery, current neck symptoms, and health-related quality of life. Radiological outcomes were evaluated from the cervical plain radiographs, which were taken either at the end of the follow-up as a part of the present study or earlier on for other clinical reasons, but at least 2 years after index surgery., Results: The total rate of reoperations and further cervical surgeries during the follow-up of a median of 14 years was 7/38 (18%) in the TDR group and 6/76 (8%) in the ACDF group (p=.096, ns.). Total disc replacement patients were reoperated earlier, and the 5-year reoperation rate was significantly higher in the TDR group (11% vs 1.3%, p=.026). None of the TDR patients underwent further cervical surgery more than 6 years after index surgery, whereas 5/6 (83%) of the reoperated ACDF patients were reoperated after that time. There were no significant differences in the NDIs between the patient groups. The employment rate and health-related quality of life were slightly higher in the TDR group, but the differences were statistically nonsignificant. TDR was significantly better at maintaining the angular range of motion at the operated level, and the fusion rate was significantly lower among this group., Conclusions: There were no significant differences in the long-term outcomes of ACDF and TDR when measured by reoperation rates, employment status, NDI, EuroQoL, and satisfaction with surgery. Reoperation rate and, on the other hand, employment rate and health-related quality of life, were higher in the TDR group, but the differences were statistically nonsignificant. However, TDR patients were reoperated earlier, and the 5-year reoperation rate was significantly higher in the TDR group. Randomized long-term studies in which these methods are compared are needed to further clarify the differences between them., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Purpose: Low back pain is a significant socio-economic problem which is expected to deepen. Degenerative disc disease is considered to be one of its main causes. Unsuccessful conservative treatments usually lead to surgical treatments, including methods providing pain relief by vertebral fusion in the affected segment. However, this leads to changes in biomechanics, which is why approximately 30 years ago total disc replacements appeared. This work aims at determining the current state of treatments with this kind of replacement, comparing the results with those of fusion methods and assessing why fusion continues to dominate. Current treatments of degenerative disc disease by advanced procedures (regenerative and gene therapy, 3D printing) is also examined and evaluated, and future developments are considered., Methods: A critical review based on available scientific articles from online databases. The main keywords used were "lumbar", "total", "disc" and "replacement", supplemented according to the individual, monitored areas ("follow-up", "fusion", "future" etc.). For the articles found through database search (n = 895), narrower selection was made and the result was 33 articles included in review., Review: Total disc replacements have not yet satisfactorily demonstrated that they are superior to fusion methods in long term follow-up. Advanced methods are in their infancy., Conclusions: Additional research and development of total disc replacements is still necessary. For implants, the 3D scan - 3D model - 3D printing chain and its related technologies are increasingly important. The development of regenerative procedures using induced pluripotent stem cells and gene therapies is important, but conservative treatments and primary prevention should also be developed because regenerative procedures and gene therapies apparently will not be used routinely until the future.

Objective: Headache relief after anterior cervical spine surgery has been reported. No study, however, has followed patients out to 10 years to assess the durability of headache improvement. The authors analyzed a group of patients with a 10-year follow-up after one- or two-level cervical disc arthroplasty (CDA) from an FDA investigational device exemption (IDE) study., Methods: The authors performed a post hoc analysis of 189 patients treated with CDA from the 9 highest enrolling sites in a prospective multicenter randomized US FDA IDE clinical trial. Patients had one- or two-level CDA at contiguous levels from C3 to C7 using the Mobi-C device. The authors evaluated headache scores from the headache section of the Neck Disability Index (NDI), along with associated demographic variables (age, sex, race, ethnicity, and BMI). Preoperative and 10-year postoperative headache scores were analyzed. Primary analysis was conducted via the Wilcoxon rank-sum test, followed by univariate and multivariable logistic regression., Results: After accounting for age, BMI, race, ethnicity, and sex, there was sustained headache improvement 10 years after CDA (p = 0.04). Preoperatively, the median NDI score was 3.00 (IQR 1.00-4.00) and after 10 years it was 1.00 (IQR 0.00-2.00), with a decrease in the NDI score by 1.00 point (95% CI 0.00-2.00, p = 0.04). For one-level CDA, the median NDI score was 3.00 (IQR 1.00-4.00) preoperatively but 1.00 (IQR 0.00-2.00) at 10 years, with an estimated reduction in the NDI score of 1 point (95% CI 1.00-2.00, p < 0.0001). For two-level CDA, the median NDI score was 3.00 (IQR 1.75-4.00) preoperatively and 1.00 (IQR 0.00-2.00) at 10 years, with an estimated reduction in the NDI score of 1 point (95% CI 1.00-2.00, p < 0.0001)., Conclusions: Headache relief provided by cervical CDA, for symptomatic C3-7 cervical spondylosis, was sustained even 10 years after surgery. There was no difference in headache improvement between the one- and two-level CDA groups, or among BMI, sex, race, and ethnicity strata.

Purpose: We evaluated the long-term safety, mobility and complications of cervical total disc arthroplasty with the Baguera ® C prosthesis over 10 years., Methods: We included 91 patients treated by arthroplasty for cervical degenerative disc disease. A total of 113 prostheses were implanted (50 one-level, 44 two-level and 19 hybrid constructs). They were assessed for complications, clinically, with NDI and SF-12 questionnaires and by independent radiologists for ROM, HO, disc height and adjacent level degeneration., Results: No spontaneous migration, loss of fixation, subsidence, vascular complication or dislocation were observed. The reoperation rate was 1%. About 82.7% of the patients were pain free. About 9.9% were taking occasional grade I painkillers. Motricity and sensitivity were preserved in 98.8% and 96.3%. The NDI showed an average functional disability of 17.58%, 26% lower than preoperatively. The SF-12 scores were close to normal health. The average ROM at the treated level was 7.4°. Motion was preserved in 86.6%. Lack of motion was observed in 13.4%. Grades II and III H0 were present in 53.7% and 31.7%, respectively, Grade IV was present in 13.4%. Motion was preserved in 100% of the grades 0-III. The preoperative adjacent level disc height of 4.3 mm remained stable during all the follow-ups at 4.4 mm and 4.2 mm, respectively, at 5 and 10 years., Conclusions: After 10 years, cervical arthroplasty with the Baguera ® C prosthesis presents excellent safety and functional results and low complications. Motion was preserved in 86.6%, with a 7.4° ROM. Although common, HO did not hinder motion. Adjacent disc height preservation confirms some adjacent level degeneration protection., (© 2023. The Author(s).)

Study Design: Systematic review and meta-analysis., Objective: This study aimed to assess the incidence of heterotopic ossification (HO) 10 years after cervical disk replacement (CDR)., Summary of Background Data: HO is a common complication after CDR and may limit the range of motion of the artificial disk. As HO usually progresses slowly, a long-term follow-up is required to better understand its incidence. In recent years, the increasing number of original articles reporting 10-year outcomes gives us the opportunity to better understand the long-term incidence of HO., Materials and Methods: We searched PubMed, Medline, Embase, and Cochrane Library databases to identify eligible studies. The incidence of HO was pooled, and subgroup analysis was performed. Meta-regression analyses were conducted to identify factors contributing to heterogeneity., Results: Eleven studies with at least 10 years of follow-up comprising 1140 patients who underwent CDR were included. The pooled incidence of overall HO was 70% (95% CI, 60%-81%) at 10 years postoperatively, 60% (95% CI, 44%-75%) at five or six years postoperatively, and 50% (95% CI, 27%-72%) at one or two years postoperatively. The pooled incidence of severe HO (grade 3 or 4) was 37% (95% CI, 29%-45%), and mild HO (grade 1 to 2) was 30% (95% CI, 17%-44%) at 10 years of follow-up. Pooled range of motion decreased from 8.59° before surgery to 7.40° 10 years after surgery. Subgroup analysis showed that HO incidence differed according to the prosthesis type. The earlier publication was associated with a higher pooled incidence of severe HO in the meta-regression analysis., Conclusions: This is the first meta-analysis providing detailed information on the pooled 10-year incidence of HO after CDR. The incidence of HO seems to increase with the length of follow-up., Level of Evidence: 3., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Cervical disc replacement (CDR) is an alternative treatment to anterior cervical discectomy and fusion (ACDF), which is the current gold standard, for degenerative cervical diseases such as cervical spondylotic myelopathy and cervical radiculopathy. CDR has several theoretical benefits over ACDF, including preservation of motion, earlier return to unrestricted activity, and potentially a lower risk of adjacent-segment disease. Recent literature has reported positive clinical results for CDR, but few studies have investigated the long-term risk of revision surgery of CDR versus ACDF. The purpose of this study was to identify and analyze the epidemiological, clinical, and operative risk factors that affect revision rates following single-level CDR and ACDF procedures., Methods: A retrospective cohort was extracted from the Statewide Planning and Research Cooperative System using ICD-9 and CPT codes. Inclusion criteria were adult patients undergoing primary, subaxial (C3-7), single-level ACDF or CDR for cervical radiculopathy and/or cervical spondylotic myelopathy between 2005 and 2013. Survivability was defined as the time between the index procedure and the presence of a subsequent discharge record for cervical spinal fusion or disc replacement. Statistical analyses were performed using chi-square tests, t-tests, Cox proportional hazards models, and a Kaplan-Meier plot., Results: A total of 7450 patients were included in this study (6615 ACDF and 835 CDR). When adjusted for patient demographics, the hazard ratios showed no significant differences in the incidence of revision risk between the two cohorts. The CDR cohort had a higher incidence of postoperative dysphagia (p < 0.05). Patients undergoing ACDF had a longer average hospital stay (2.8 vs 1.9 days, p < 0.001). There was no significant difference in time to revision surgery (p = 0.486)., Conclusions: CDR and ACDF have both been shown to be effective treatments for cervical spine disease. CDR patients had a shorter average inpatient hospital stay compared with ACDF patients but tended to experience dysphagia more frequently. There was a tendency toward increased survivability of CDR; however, this was not found to be statistically significant at any time point. The large size and heterogeneity of each cohort and the availability of > 10 years of surveillance data differentiate this study from other published literature. This investigation has limitations inherent to large data analysis studies, including the implementation and inaccuracy of diagnosis and procedural coding; however, this reflects real-world use of coding by practitioners.

Background: Cervical disk arthroplasty replacement (CDA) was developed to avoid specific disadvantages of cervical fusion. The purpose of this paper is to provide 10-year follow-up results of an ongoing prospective study after CDA., Methods: Three hundred eighty-four patients treated using the Mobi-C (ZimVie, Troyes, France) were included in a prospective multicenter study. Routine clinical and radiologic examinations were reported preoperatively and postoperatively with up to 10-year follow-up. Complications and revision surgeries were also documented., Results: At 10 years showed significant improvement in all clinical outcomes [Neck Disability Index, visual analog scale (VAS) for arm and neck pain, physical component summary of SF36, and mental component summary of SF36). Motion at the index level increased significantly over baseline (mean range of motion=7.6 vs. 8 degrees at five years and 6.0 degrees preoperatively; P <0.001) and 71.3% of the implanted segments remained mobile (range of motion>3 degrees). Adjacent disks were also mobile at 10 years with the same mobility as preoperatively. At 10 years, 20.9% of the implanted segments demonstrated no heterotopic ossification. Thirty-four patients (8.9%) experienced 41 adverse events, with or without reoperation during the first five years. We found only two additional surgeries after five years. We observed an increased percentage of working patients and a decrease in medication consumption. Regarding the overall outcome, 94% of patients were satisfied., Conclusions: Our 10-year results showed significant improvement in all clinical outcomes, with low rates of revision or failure. This experience in patients with long-term follow-up after CDA endorses durable, favorable outcomes in properly selected patients., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background Context: Motion preserving anterior cervical disc arthroplasty (ACDA) in patients with cervical radiculopathy was introduced to prevent symptomatic adjacent segment disease as compared to anterior cervical discectomy and fusion (ACDF)., Purpose: To evaluate the long-term outcome in patients with cervical radiculopathy due to a herniated disc undergoing ACDA, ACDF or ACD (no cage, no plate) in terms of clinical outcome measured by the Neck Disability Index (NDI). Likewise, clinically relevant adjacent segment disease is assessed as a long-term result., Study Design: Double-blinded randomized controlled trial., Patient Sample: A total of 109 patients with one level herniated disc were randomized to one of the following treatments: ACDA, ACDF with intervertebral cage, ACD without cage., Outcome Measures: Clinical outcome was measured by patients' self-reported NDI, Visual Analogue Scale (VAS) neck pain, VAS arm pain, SF36, EQ-5D, perceived recovery and reoperation rate. Radiological outcome was assessed by radiographic cervical curvature and adjacent segment degeneration (ASD) parameters at baseline and up until five years after surgery., Methods: To account for the correlation between repeated measurements of the same individual Generalized Estimated Equations (GEE) were used to calculate treatment effects, expressed in difference in marginal mean values for NDI per treatment group., Results: Clinical outcome parameters were comparable in the ACDA and ACDF group, but significantly worse in the ACD group, though not reaching clinical relevance. Annual reoperation rate was 3.6% in the first two years after surgery, declined to 1.9% in the years thereafter. The number of reoperations for ASD was not lower in the ACDA group, while the number of reoperations at the index level was higher after ACD, when compared to ACDF and ACDA., Conclusions: A persisting absence of clinical superiority was demonstrated for the cervical disc prosthesis five years after surgery. Specifically, clinically relevant adjacent level disease was not prevented by implanting a prosthesis. Single level ACD without implanting an intervertebral device provided worse clinical outcome, which was hypothesized to be caused by delayed fusion. This stresses the need for focusing on timely fusion in future research., Competing Interests: Declaration of competing interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background Context: The theoretical advantage of cervical disc arthroplasty includes preserved motion at the cervical level, which may reduce degeneration of the adjacent segments. The long-term follow-up results are still controversial., Purpose: The present study aimed to retrospectively study the long-term efficacy and complications of cervical disc arthroplasty using a single commercially-available device in a single center., Study Design: This was a propensity-score matched cohort study., Patient Sample: This study enrolled 148 single-level cervical degenerative disease patients from January 2009 to March 2012. After 1:1 propensity score matching, 39 patients remained in the ACDF or ACDR groups., Outcome Measures: The outcome measures were neurological functions (Neck Disability Index (NDI) and Japan Orthopedic Association (JOA) scores), radiographic evaluations (cervical curvature, operative segment range of motion, degenerative condition of adjacent segments, heterotopic ossification (HO) of the surgical segment), and complications., Methods: NDI and JOA scores were used to evaluate patient neurological functions. Cervical curvature (C2-C7 Cobb angle) and operative segment range of motion (ROM) were compared between the two groups. Grading criteria for osteophyte formation were used to evaluate the degenerative condition of adjacent segments. HO after ACDR was graded according to the McAfee grading method., Results: The average follow-up time was 119.3 ±17.2 months. Satisfactory improvements in neurological function were obtained for both the ACDR and ACDF groups. There were no significant differences in VAS or NDI scores between the two groups. In the ACDR group, the ROM of the operative segment increased from 6.7 ±4.3° before the operation to 8.9 ±3.5° on the second day after the operation (p<.001). The ROM of the operative segment was 8.1 ±4.0° at the 1-year follow-up, 7.2 ±3.6° at the 2-year follow-up, 5.7 ±4.5° at the 5-year follow-up and 4.3 ±3.9° at the last follow-up. ASD was more likely to develop in the caudal adjacent segments and progressed with the follow-up time. At the last follow-up, HO was present in 27 patients (69.23%), while high-grade HO (McAfee scores III and IV) was detected in 6 patients (15.38%)., Conclusions: Through nearly 10 years of follow-up, ACDR was as effective as ACDF for treating single-level degenerative cervical disc disease. However, HO and the role of ACDR in the protection of ASD remains to be further observed and followed up., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2022. Published by Elsevier Inc.)

Objectives: The objectives of this study were to identify the risk factors and incidence of anterior bone loss (ABL) after Baguera C cervical disc arthroplasty (CDA) and identify whether design differences in artificial discs affect ABL., Methods: In this retrospective radiological review of patients who underwent single-level Baguera C CDA in a medical center, the extent of ABL and the following radiological parameters were recorded: global and segmental alignment angle, lordotic angle (or functional spinal unit angle), shell angle, global range of motion (ROM), and ROM of the index level. ABL at the index level was grade 0-2. Grade 0 was defined as no remodeling, grade 1 as spur disappearance or mild change in body contour, and grade 2 as obvious bone regression with Baguera C Disc exposure., Results: Combining grade 1 and grade 2, ABL was found in 56 upper adjacent vertebrae and 52 lower adjacent vertebrae of the 77 patients. Only 18 patients (23.4%) had no ABL. Shell angle differed significantly between ABL grades of both the upper and lower adjacent level: 0.0° in grade 0 and 1 ABL vs. 2.0° in grade 2 ABL of the upper adjacent level ( p < 0.05); and 0.0° in grade 0 and 1 ABL vs. 3.5° in grade 2 ABL of the lower adjacent level ( p < 0.05). A female predominance of ABL was found. Hybrid surgery and artificial disc size were also related to ABL., Conclusions: ABL is more common in Baguera C Disc arthroplasty than Bryan Disc arthroplasty. Larger shell angle was related to ABL after CDA with Baguera C Discs, which may indicate that shell angle is pivotal in determining the incidence of ABL after CDA. Females had more ABL with Baguera C Disc arthroplasty; this might be related to shorter endplate lengths as well as a smaller endplate-implant mismatch., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Chih-Chang Yang et al.)

Objective: American College of Surgeons National Surgical Quality Improvement Program Participant Use File data from 2014 through 2019 were used to compare 1- and 2-level anterior cervical discectomy and fusion (ACDF) and cervical total disc replacement (cTDR) with respect to: patient demographics, comorbidities, adverse events, and 30-day morbidity rates., Methods: One- and 2-level ACDF and cTDR patients were identified by current procedural terminology codes. Demographics, comorbidities, and adverse events were summarized. Unmatched cohorts were compared using Wilcoxon Rank Sum test for continuous variables, Pearson χ 2 test for categorical variables, and 30-day morbidity using inverse probability of treatment weighted log-binomial regression., Results: American College of Surgeons National Surgical Quality Improvement Program 2014 through 2019 Participant Use File datasets represent 4,862,497 unique patients, identifying 13,347 1-level, 6933 2-level ACDF, 3114 1-level, and 862 2-level cTDR patient cohorts. Statistically significant differences between cohorts are extensive: age, sex, race, admission status, patient origin, discharge disposition, emergent surgery, surgical specialty, American Society of Anesthesiologists classification, wound class, operative time, hospital LOS, BMI, functional status, smoking, diabetes, dyspnea, chronic obstructive pulmonary disease, congestive heart failure, hypertension, renal failure, dialysis, cancer, steroid use, anemia, bleeding disorders, systemic sepsis, and number of concurrent comorbid conditions. Inverse probability of treatment weighted log-binomial models, demonstrated increased risk of deep venous thrombosis/thrombophlebitis, pulmonary embolism, deep incisional surgical site infection, pneumonia, and unplanned return to operating room associated with ACDF while increased risk of cerebral vascular accident/stroke with neurological deficit and myocardial infarction associated with cTDR. The composite complications outcome favors cTDR over ACDF for 30-day morbidity. No mortalities occurred within the cTDR cohort., Conclusions: Adjusting for demographics and comorbidities; ACDF has a higher average risk of adverse event. When ACDF and cTDR are equipoise, consideration for cTDR may be indicated in populations with higher rates of comorbid conditions., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: We sought to characterize trends in demographics, comorbidities, and postoperative complications among patients undergoing primary and revision cervical disc replacement (pCDR/rCDR) procedures., Methods: In this retrospective database study, the Premier Healthcare database was queried from 2006 to 2019. Annual proportions or medians were calculated for patient and hospital characteristics, comorbidities, and postoperative complications associated with CDR surgery. Trends were assessed using linear regression analyses with year of service as the sole predictor., Results: A total of 16,178 pCDR and 758 rCDR cases were identified, with a median (IQR) age of 46 (39; 53) and 51 (43; 60) years among patients, respectively. The annual number of both procedures increased between 2006 and 2019, from 135 to 2220 for pCDR (p < 0.001), and from 17 to 49 for rCDR procedures (p < 0.001), with radiculopathy being the main indication for surgery in both groups. Mechanical failure was identified as a major indication for rCDR procedures with an increase over time (p = 0.002). Baseline patient comorbidity burden (p = 0.045) and complication rates (p < 0.001) showed an increase. For both procedures, an increase in outpatient surgeries and procedures performed in rural hospitals was seen (pCDR: p = 0.045; p = 0.006; rCDR: p = 0.028; p = 0.034)., Conclusion: PCDR and rCDR procedures significantly increased from 2006 to 2019. At the same time, comorbidity burden and complication rates increased, while procedures were more often performed in an outpatient and rural setting. The identification of these trends can help guide future practice and lead to further areas of research., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Anterior cervical disc replacement (ACDR) using cervical artificial disc (CAD) has the advantage of maintaining the range of motion (ROM) at the surgical level, subsequently reducing the postoperative risk of adjacent disc disease. Following the approval for the clinical use in Japan, a post-marketing surveillance (PMS) study was conducted for two different types of CAD, namely, Mobi-C (metal-on-plastic design) and Prestige LP (metal-on-metal design). The objective of this prospective observational multicenter study was to analyze the first 2-year surgical results of the PMS study of 1-level ACDR in Japan. A total of 54 patients were registered (Mobi-C, n = 24, MC group; Prestige LP, n = 30, PLP group). Preoperative neurological assessment revealed radiculopathy in 31 patients (57.4%) and myelopathy in 15 patients (27.8%). Preoperative radiological assessment classified the disease category as disc herniation in 15 patients (27.8%), osteophyte in 6 patients (11.1%), and both in 33 patients (61.1%). The postoperative follow-up rates at 6 weeks, 6 months, 1 year, and 2 years after ACDR were 92.6%, 87.0%, 83.3%, and 79.6%, respectively. In both groups, patients' neurological condition improved significantly after surgery. Radiographic assessment revealed loss of mobility at the surgical level in 9.5% of patients in the MC group and in 9.1% of patients in the PLP group. No secondary surgeries at the initial surgical level and no serious adverse events were observed in either group. The present results suggest that 1-level ACDR is safe, although medium- to long-term follow-up is mandatory to further verify the validity of ACDR for Japanese patients.

Objective: Although cervical disc arthroplasty (CDA) has reportedly been associated with similarly low incidences of complications to anterior cervical discectomy and fusion, the phenomenon of anterior bone loss (ABL) is unique to CDA and has only recently gained notice. This study thus aimed to investigate the incidence of ABL and its correlation with cervical alignment post-operation., Methods: Consecutive patients who received CDA for herniated disc or spondylosis were retrospectively reviewed. The development and extent of ABL was detected by comparison of preoperative and postoperative serial images for the relative position of the anterior vertebral body with the CDA devices and graded into 3 levels: grade 1 (minor bone loss), grade 2 (anterior portion of the vertebral body without exposure of the artificial disc), and grade 3 (anterior portion of the vertebral body with exposure of the device)., Results: A total of 41 patients were analyzed with a mean follow-up of 24.1 months. Under serial radiologic examinations during follow-up, all patients (41 of 41 = 100%) had bone loss of various degrees, with grade 3 ABL the most common (30 of 41 = 73.1%). There were 8 and 3 patients who had grades 2 and 1 ABL, respectively. The changes of the Cobb angle (ΔCobb) trended towards higher grades of ABL., Conclusions: During the mean follow-up of 2 years, ABL was a common radiologic finding. More than half of the patients (26 of 41, 63.4%) in the series gained cervical lordosis (ΔCobb >0) after CDA. These patients with increased cervical lordosis (ΔCobb >0) after CDA had higher grades of ABL., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: Anterior cervical discectomy and fusion (ACDF) surgery is commonly performed to treat cervical degenerative disc disease (CDDD). The lost of range of motion (ROM) is also found after ACDF, which contributes to degenerate in adjacent segment disease (ASD). Artificial cervical disc replacement (ACDR), an alternative to ACDF, is developed to preserve the ROM and reduce ASD. This article aims to compare the outcomes between ACDR and ACDF in the short-, mid-, and long-term., Methods: Databases including Cochrane, Embase, PubMed, and Web of Science were searched. Only RCTs were included in this meta-analysis, and the search strategy followed the requirements of the Cochrane Handbook. The strength of evidence was assessed using GRADE. Two reviewers independently assessed the methodological quality of each included study and extracted the relevant data., Results: Thirty prospective RCTs were included. Prolonged operative duration, better overall success, neurological success, and NDI success rates were found in ACDR group in all follow-up periods, with lower dysphagia/dysphonia during short-term follow-up. Moreover, a lower ASD was found in ACDR group during long-term follow-up and overall analysis, with lower reoperation rates in all follow-up periods. Comparable length of hospital stay and blood loss were found in both groups. Moreover, ASD was similar in short- and mid-term follow-ups, while dysphagia/dysphonia incidence was similar in mid- and long-term follow-ups. The incidence of implant events was comparable in all follow-up periods (p > 0.05)., Conclusions: ACDR is as effective as ACDF and superior for some success rates. Disc replacement can reduce the risk of dysphagia/dysphonia, ASD, and re-operation., (© 2022. The Author(s) under exclusive licence to SICOT aisbl.)

Wear-induced complications after cervical disc replacement (CDR) are rare. A literature review on this topic found only a few case reports. We present a case of late complications after implantation of two cervical disc replacements, which resulted in infectious/abrasion-induced mixed-type inflammation with extensive osteolysis. The diagnostic workup, surgical therapy and outcome are presented and discussed with a review of the recent literature., Competing Interests: The authors declare that they have no conflict of interest./Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Background: According to published meta-analyses, cervical total disc replacement (CTDR) seems to be superior to anterior cervical decompression and fusion (ACDF) in most clinical parameters. Despite short-term clinical success of CTDR, there are concerns regarding long-term durability of these prostheses., Methods: This prospective study involved 382 patients who received standalone CTDR or a hybrid procedure (ACDF/CTDR). A retrospective comparison between different CTDR devices was conducted regarding patient-reported outcome measures (PROMs), failure scenarios, and revision surgeries. The M6-C™ Artificial Cervical Disc (Orthofix, Lewisville, Texas) cohort was compared to the other CTDR devices clinically. Etiological reasons for revision, and the surgical technique of the revision was investigated., Results: Fifty-three patients received M6-C CTDR. Eighteen patients (34%) were revised at an average of 67 months postoperatively for wear-induced osteolysis. There were three additional cases of pending revision. The PROMs of the two groups were similar, indicating that the failure mode (wear-induced osteolysis) is often asymptomatic. The demographics of the two groups were also similar, with more women undergoing revision surgery than men. There were three one-level CTDR, four two-level hybrids, seven three-level hybrids, and three four-level hybrids revised anteriorly. Sixteen patients underwent removal of the prosthesis and were treated according to the extent of osteolysis. There were four vertebrectomies, six revisions to ACDF, and six revisions to another CTDR. One patient underwent supplemental fixation using a posterior approach. The other CTDR cohort had an incidence of 3.3% at the equivalent time, and none of these were due to osteolysis or wear-related events., Conclusions: There is a concerning midterm failure rate related to ultra-high-molecular-weight-polyethylene wear-induced osteolysis in the M6-C. Patients implanted with the M6-C prosthesis should be contacted, informed, and clinically and radiologically assessed., (© 2022. The Author(s).)

Background Context: Lumbar total disc replacement (TDR) is an alternative to lumbar fusion in the treatment of lower back pain and reduces the risk of adjacent segment degeneration. Heterotopic ossification (HO) has been identified as a common complication following lumbar TDR., Purpose: This systematic review aims to determine the prevalence, risk factors and clinical and radiological impact of HO following lumbar TDR., Study Design: Systematic Review., Methods: MEDLINE, Scopus, PubMed and Cochrane Central were searched for articles that referred to lumbar TDR and HO. The hits were assessed against inclusion and exclusion criteria. Data from each included study was extracted and analysed with respect to the study aims., Results: Twenty-six studies were included in this review and the pooled prevalence of HO was estimated to be between 13.2% (participants) and 15.3% (vertebral levels). TDR clinical outcomes were not found to be reduced by HO and there was insufficient data to identify a given impact upon radiological outcomes. Age and follow up time were identified as potential risk factors for HO., Conclusions: This review was hampered by inconsistencies in the reporting of HO across the studies. We therefore recommend that a set of guidelines should be produced to aid future researchers and reduce the risk of bias., (© 2022. The Author(s).)

Objective: Anterior cervical discectomy and fusion (ACDF) has been considered the standard treatment for degenerative cervical disc disease; however, recent trials have shown comparable outcomes with cervical disc arthroplasty (CDA). This study aimed to observe disparities in treatment paradigms of single-level cervical disc diseases and compare inpatient outcomes between procedures., Methods: A retrospective cohort of patients treated for single-level cervical disc herniation or degeneration without myelopathy was queried from the Nationwide Inpatient Sample spanning 2012-2015. Multivariate logistic regression was performed to assess the effects of demographics, temporality of admission, and hospital characteristics on odds of receiving CDA versus ACDF. Propensity-score matching was performed to compare cost, length of stay (LOS), non-home discharge, and inpatient complications., Results: In total, 1028 CDAs and 44,374 ACDFs were performed for single-level cervical disc disease during 2012-2015. Matched comparison showed that while non-home discharges were not different between CDA and ACDF (P = 0.248), patients who received CDA had a 0.19-day shorter LOS (P < 0.001) and $4694 greater total cost (P < 0.001). There were no statistically significant differences in inpatient complication rates. Multivariate analysis showed that patients in the 26th-50th percentile, 51st-75th percentile, and 76th-100th percentile of median household income had greater odds of CDA compared with patients in the 0-25th percentile (odds ratio [OR] 1.35, P = 0.003; OR 1.31, P = 0.013; OR 1.34, P = 0.011, respectively). Patients with private insurance had greater odds of receiving CDA compared with patients on Medicare (OR 1.91, P < 0.001)., Conclusions: CDA was associated with shorter LOS but greater costs compared with ACDF. Patients with greater median income and private insurance were more likely to receive CDA., (Published by Elsevier Inc.)

Cervical disc arthroplasty (CDA) is an approved surgical treatment option in selected patients with cervical spinal disc degeneration. Even though CDA is a standard procedure since 20 years, there is a lack of information about long term performance. The published reoperation rates after CDA are low and comparable to anterior cervical fusion. The authors describe a severe failure and dysfunction with a partial core dislocation of a cervical prosthesis into the spinal canal (M6-C, Spinal Kinetics, Sunnyvale, CA, USA). Six years after implantation of a cTDR (cervical Total Disk Replacement) of the M6 type at C4/5 level, a 52 year-old women presented herself with new clinical signs of cervical myelopathy and radicular pain. Complete posterior dislocation of the central core of the implant into the spinal canal was identified as a cause. The failed device was removed completely and an ACCF (anterior cervical corpectomy and fusion) was performed. Intraoperatively, rupture of the posterior portion of the mesh tissue with posterior dislocation of the whole prosthesis core was detected. This is the second described case of a severe implant failure with core dislocation in this type of cTDR device. Even though there are thousands of successful implantations and middle term outcomes, it seems to be necessary to continue with long term radiological follow up to exclude similar failure in this type of prosthesis., Competing Interests: The authors declare that they have no conflict of interest./Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Objectives: To evaluate how well the degree of pain relief after discoblock predicts the disability outcome of subsequent fusion or total disc replacement (TDR) surgery, based on short-term Oswestry Disability Index (ODI) scores., Methods: We retrospectively analyzed a set of patients who had undergone discoblock and subsequent fusion or TDR surgery of the same lumbar intervertebral disc due to suspected discogenic chronic LBP between 2011 and 2018. We calculated the degree of pain relief following discoblock (ΔNRS) and the changes in both absolute and percentual ODI scores (ΔODI and ΔODI%, respectively) following fusion or TDR surgery. We analyzed the statistical significance of ΔNRS and ΔODI and the correlation (Spearman's rho) between ΔNRS and ΔODI%. The fusion and TDR group were analyzed both in combination and separately., Results: Fifteen patients were eligible for the current study (fusion n=9, TDR n=6). ΔNRS was statistically significant in all groups, and ΔODI was statistically significant in the combined group and in the fusion group alone. The parameters of both decreased. We found a Spearman's rho of 0.57 (p=0.026) between ΔNRS and ΔODI% for the combined group. The individual Spearman's rho values were 0.85 (p=0.004) for the fusion group and 0.62 (p=0.191) for the TDR group., Conclusions: We suggest that discoblock is a useful predictive criterion for disability outcome prior to surgery for discogenic LBP, especially when stabilizing spine surgery is under consideration., Ethical Committee Number: 174/2019 (Oulu University Hospital Ethics Committee)., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Study Design: Retrospective study., Objective: The aim of this study was to evaluate the long-term clinical and radiographic outcomes of cervical arthroplasty using the ProDisc-C Vivo prosthesis., Summary of Background Data: Previous reports have shown that cervical arthroplasty with ProDisc-C artificial disc has acceptable clinical outcomes at 5-year and 10-year follow-ups., Methods: Clinical and radiographic evaluations, including dynamic flexion-extension lateral images, were performed at baseline and at the 5-year follow-up., Results: Twenty-eight patients who underwent single-level ProDisc-C Vivo arthroplasty were followed-up for a mean period of 65 months. The range of motion at the operated level was 8.9° ± 2.3° at baseline and 8.3° ± 4.8° at the final follow-up (P  = 0.494). Fourteen of 28 levels (50%) developed heterotopic ossification (HO). According to McAfee's classification, one level was classified as grade I, nine levels as grade II, two levels as grade III, and two levels as grade IV. Only four of 28 levels (14.3%) had severe HO. Among patients with cervical spondylotic myelopathy, mJOA score was 13.9 ± 2.5° at baseline and 15.9° ± 1.0° at the final follow-up (P  = 0.001 < 0.05). Among patients with cervical spondylotic radiculopathy, Visual Analog Scale (VAS) neck and shoulder was 5.4 ± 1.4° at baseline and 0.7° ± 1.2° at the final follow-up (p = 0.000 < 0.05), VAS arm was 5.1 ± 2.8° at baseline and 0.5° ± 1.2° at the final follow-up (P  = 0.000 < 0.05). A total of 49 adjacent segments were observed and 13 (26.5%) had adjacent segment degeneration. No patient developed recurrent cervical radiculopathy or myelopathy due to adjacent segment disease. No patient underwent re-operation., Conclusion: ProDisc-C Vivo arthroplasty had satisfactory clinical and radiographic outcomes at 5-year follow-up.Level of Evidence: 4., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective analysis was performed on data from 251 patients that were included in two randomized, double-blinded clinical trials comparing clinical results of anterior cervical discectomy and arthroplasty (ACDA) to anterior cervical discectomy and fusion (ACDF), and anterior cervical discectomy (ACD), for single-level disc herniation., Objective: This study aimed to investigate whether the ACDA procedure offers superior clinical results 2 years after surgery, to either ACDF or ACD without instrumentation, in the entire group of patients or in a particular subgroup of patients., Summary of Background Data: The cervical disc prosthesis was introduced to provide superior clinical outcomes after ACD., Methods: Neck Disability Index (NDI), and subscales of the 36-item short-form health survey (SF-36) and McGill pain score were collected at baseline, 1 year and 2 years after surgery. Reoperations and complications were also evaluated. A preliminary subgroup analysis was performed for age, disc height, body mass index (BMI), smoking, and sex., Results: The NDI decreased comparably in all treatment arms to circa 50% of the baseline value and marginal mean NDI differences varied from 0.4 to 1.1 on a 100 point NDI scale, with confidence intervals never exceeding the 20-point minimal clinical important difference (MCID). Secondary outcome parameters showed comparable results. Preliminary subgroup analysis could not demonstrate clinically relevant differences in NDI between treatments after 2 years., Conclusion: After combining data from two Randomized Controlled Trials it can be concluded that there is no clinical benefit for ACDA, when compared with ACDF or ACD 2 years after surgery. Preliminary subgroup analysis indicated outcomes were similar between treatment groups, and that no subgroup could be appointed that benefited more from either ACD, ACDF, or ACDA.Level of Evidence: 1., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: The purpose of our meta-analyses is to find the most appropriate surgical technique treating lumbar degenerative disc disease (DDD). Spinal fusion is the conventional treatment for lumbar DDD. Total disc replacement (TDR) has been developed to avoid negative effects of fusions by preserving functionality. To our knowledge, there is no evaluation comparing meta-analytically the clinical results of three different surgical techniques with same inclusion and exclusion criteria for treating DDD., Methods: The surgical techniques TDR, anterior lumbar interbody fusion (ALIF) and circumferential fusion (CFF) are pairwise meta-analytically compared. Primary outcomes are pain measured by the Visual Analogue Scale (VAS) and function measured by the Oswestry Disability Index (ODI). Secondary outcomes are the mean number of complications per case (MNOC) at surgery and follow-up and the overall MNOC., Results: In our systematic search, we found finally six prospective studies with the minimum follow-up of two years: four randomized controlled trials and two cohort studies. In VAS and ODI, TDR is proved to be superior to ALIF and CCF (p < 0.05), whereat ALIF is more effective than CFF without statistical significance. CFF presents the best result in complications with the lowest overall MNOC (0.1), followed by TDR (1.2) and ALIF (1.5)., Conclusion: According to our meta-analyses, we regard TDR to be the most appropriate surgical technique treating DDD, followed by ALIF. Further studies with a longer follow-up are needed using the same methodical approach to strengthen the VAS and ODI results and to explain the discrepant result to complications., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Heterotopic ossification (HO) is a common complication after cervical disc replacement (CDR). Biomechanical factors including endplate coverage and intervertebral disc height change may be related to HO formation. However, there is a dearth of quantitative analysis for endplate coverage, intervertebral height change and their combined effects on HO., Methods: Patients who underwent single-level or two-level CDR with Prestige-LP were retrospectively reviewed. Clinical outcomes were evaluated through Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI) score, and visual analogue scale (VAS) score. Radiological data, including the prosthesis-endplate depth ratio, intervertebral height change, posterior heterotopic ossification (PHO) and angular parameters, were collected. Logistic regression analysis was used to identify the potential risk factors. Receiver operating characteristic curves were plotted and the cut-off values of each potential factors were calculated., Results: A total of 138 patients with 174 surgical segments were evaluated. Both the prosthesis-endplate depth ratio (P < 0.001) and post-operative disc height change (P < 0.001) were predictive factors for PHO formation. The area under the curve (AUC) of the prosthesis-endplate depth ratio, disc height change and their combined effects represented by the combined parameter (CP) were 0.728, 0.712 and 0.793, respectively. The risk of PHO significantly increased when the prosthesis-endplate depth ratio < 93.77% (P < 0.001, OR = 6.909, 95% CI 3.521-13.557), the intervertebral height change ≥ 1.8 mm (P < 0.001, OR = 5.303, 95% CI 2.592-10.849), or the CP representing the combined effect < 84.88 (P < 0.001, OR = 10.879, 95% CI 5.142-23.019)., Conclusions: Inadequate endplate coverage and excessive change of intervertebral height are both potential risk factors for the PHO after CDR. Endplate coverage less than 93.8% or intervertebral height change more than 1.8 mm would increase the risk of PHO. The combination of these two factors may exacerbate the non-uniform distribution of stress in the bone-implant interface and promote HO development., (© 2021. The Author(s).)

Background: The newly designed cervical disc prosthesis, Pretic-I, had been finished its limited clinical use for over 5 years. At a short-term follow-up of 2 years, we obtained satisfactory clinical results. The long-term clinical efficacy and safety of Pretic-I will now be analyzed., Methods: Peri-operative parameters included intra-operative blood loss, operation time, off-bed time. Clinical parameters included visual analogue scale (VAS) for arm and neck, neck disability index (NDI), and Japanese Orthopaedic Association (JOA) score. Radiological parameters included C2-7 Cobb angle, Shell angle, and the range of motion (ROM) of C2-7, functional segment unit (FSU), and adjacent FSU. The CDA-related complications included adjacent segment degeneration (ASDeg), adjacent segment disease (ASDis), heterotopic ossification (HO), prosthesis subsidence, prosthesis displacement, and dysphagia., Results: A total 64 patients from two independent centers received a single-level CDA with Discover (n = 32) and Pretic-I (n = 32), and all of patients finished a 5-year follow-up. There're no significant differences between two groups in peri-operative parameters. The clinical parameters improved greatly in Pretic-I group (p<0.0001), and there's no statistical difference from Discover group. Furthermore, Pretic-I could slightly improve the cervical curvature (15.08 ± 11.75 to 18.00 ± 10.61, p = 0.3079) and perfectly maintain the Shell angle (3.03 ± 3.68 to 2.23 ± 4.10, p = 0.1988), cervical ROM (52.48 ± 14.31 to 53.30 ± 11.71, p = 0.8062) and FSU ROM (12.20 ± 4.52 to 10.73 ± 4.45, p = 0.2002). The incidence of high-grade HO (Grade III-IV) at the final follow-up was significantly lower in Pretic-I group than in Discover group (12.50% vs. 34.38%, p = 0.0389, Statistical Power = 95.36%). The incidences of other CDA-related complications in Pretic-I group were also well-accepted, comparable to the Discover group, without significant differences., Conclusion: CDA with Pretic-I demonstrated a well-accepted and sustained clinical outcome, with a significantly lower incidence of high-grade HO. This newly designed prosthesis is expected to become an alternative choice for cervical disc prosthesis in the future., (© 2021. The Author(s).)

Background Context: Although highlighted in joint arthroplasty studies, long-term outcomes between differing biomaterial composites, such as metal-on-metal (MoM) and metal-on-plastic (MoP) in anterior cervical disc replacement (ACDR) have not been thoroughly investigated., Purpose: The purpose of this study was to evaluate the patient-reported clinical outcomes, overall reoperation rates, complications, and rates of ASD of MoM versus MoP artificial discs in two-level ACDR for the treatment of cervical DDD., Study Design/setting: Meta-analysis and systematic review., Patient Sample: Nine hundred eighty patients (442 MoM, 538 MoP) across seven studies., Outcome Measures: Patient reported clinical outcomes (NDI, VAS-n, VAS-a), overall reoperation rates, complications, and rates of ASD., Methods: A systematic search strategy of three electronic databases (PubMed, CINAHL Plus, and SCOPUS) was conducted utilizing terms related to two-level ACDR. All studies included had a sample size of >10 patients, had a minimum 5-year follow-up, and reported data on adjacent segment disease. Cadaver studies, non-English manuscripts, articles with less than 5-year follow-up and studies in which only single-level ACDR was investigated were excluded. A total of seven studies were included in this analysis. Studies were analyzed for demographic data, clinical outcome scores (NDI, VAS-neck, and VAS-arm), overall reoperation rates, complications, and rates of ASD. A random-effects model of meta-analysis was used for groups that were determined to be heterogenous and a fixed-effects model was utilized for groups that were not. An overlap of 95% confidence intervals suggests no statistically significant difference at the p<.05 level., Results: Seven studies were included with data on 980 patients (442 MoM, 538 MoP). The study population was 52.84% female, with a mean age of 48.01 years, and a mean follow-up of 85.66 months. The mean improvement in NDI was 34.42 (95% CI, 32.49-36.36) and 29.72 (95% CI, 27.15-32.29) for the MoM and MoP groups, respectively. The mean improvement in VAS-neck was 11.20 (95% CI, 10.69-11.70) and 8.78 (95% CI, 7.81-9.74) for the MoM and MoP groups, respectively. The mean improvement in VAS-arm was 10.73 (95% CI, 9.83-11.63) and 8.49 (95% CI, 7.59-9.39) for the MoM and MoP groups, respectively. 3.85% (95% CI, 2.40-6.10) of patients who underwent ACDR with a MoM implant required reoperation compared to 5.33% (95% CI, 3.68-7.65) of patients with a MoP implant. Heterotopic ossification and dysphagia were the most common complications in both groups. The MoM cohort showed a higher incidence of HO (72.62% vs. 21.07%), but a lower incidence of dysphagia (0.96% vs. 16.31%) compared to the MoP cohort. The MoM cohort had a larger proportion of patients with ASD who underwent subsequent surgery at an adjacent level (7.89% MoM versus 1.91% MoP)., Conclusions: Our present meta-analysis suggests that the use of MoM artificial discs in two-level ACDR results in superior clinical outcome score improvement, but higher rates of ASD requiring secondary surgery compared to MoP discs after a follow-up period of 5 years or more., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Heterotopic ossification (HO) is a common complication following total disc replacement (TDR). High-grade HO is a clinically relevant complication, however, only a few studies have evaluated risk factors for high-grade HO., Objective: To evaluate potential risk factors for HO and high-grade HO and their impact on clinical outcomes., Methods: We retrospectively reviewed patients who underwent TDR or hybrid surgery (HS) with Prestige-LP (Medtronic), Discover (Depuy), and Prodisc-C (Synthes). Clinical outcomes were assessed using Japanese Orthopaedic Association, Visual Analogue Scale, and Neck Disability Index scores. Radiological variables, including preoperative ossification, global and segmental range of motion (ROM), HO, and adjacent segment degeneration (ASD) were reviewed., Results: A total of 394 patients were evaluated. HO and high-grade HO occurred in 67.77% and 11.17% patients, respectively. Preoperative ossification was significantly associated with the occurrence of HO (P < .001, OR: 3.507, 95%CI: 2.211-5.562) and high-grade HO (P = .019, OR: 2.176, 95%CI: 1.137-4.166). The ROM of replacement levels and C2-7 were significantly lower in the high-grade HO group compared to those without high-grade HO: (3.80° vs 10.18°, P < .001) and (42.81° vs 54.00°, P < .001), respectively. The incidence of ASD was significantly higher in patients with high-grade HO than those without high-grade HO (22.73% vs 11.14%, P = .048)., Conclusion: Preoperative ossification was identified as a potential risk factor for HO and high-grade HO. Patients with high-grade HO had limited ROM of replacement levels and the cervical spine and had a high incidence of ASD compared to those without high-grade HO., (© Congress of Neurological Surgeons 2021.)

Degenerative disc disease and associated cervical spondylosis or stenosis are common conditions encountered in clinical practice. These conditions may cause progressive cervical radicular or myelopathic symptoms leading to significant impairment. Although anterior cervical discectomy and fusion (ACDF) has been a reliable surgical treatment of cervical myelopathy and radiculopathy, but limitations include loss of cervical range of motion, the concern for adjacent segment degeneration and disease, pseudoarthrosis, complications related to the choice of intervertebral graft, dysphagia, as well as standard anterior cervical approach risk. Cervical total disc arthroplasty has emerged as an alternative operative procedure to ACDF., Competing Interests: Disclosure K.E. Radcliff reports the following disclosures: 4 Web Medical, stock or stock options; 4Web, paid consultant; AAOS, board or committee member; Aesculap/B. Braun, research support; Bioventus, other financial or material support; Cervical Spine Research Society, board or committee member; DePuy, A Johnson & Johnson Company, other financial or material support; Globus Medical, intellectual property royalties; Innovative Spine Devices, intellectual property royalties; ISASS, board or committee member; North American Spine Society, board or committee member; Nuvasive, other financial or material support; Orthofix, Inc., research support; Rothman Institute, stock or stock options; Simplify Medical, research support; SMISS, board or committee member; Stryker, paid consultant; Synaptive Surgical, other financial or material support; Zimmer, unpaid consultant. G. Callanan reports no disclosures., (Copyright © 2021 Elsevier Inc. All rights reserved.)