The Impact of Endplate Coverage on Heterotopic Ossification Following Cervical Disc Replacement: A Systematic Review and Meta Analysis.

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.

Risk factors of bone loss after Prestige-LP cervical disc arthroplasty.

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.

Clinical management of bone loss in cervical total disc arthroplasty: literature review and treatment recommendations.

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.

Effect of device constraint: a comparative network meta-analysis of ACDF and cervical disc arthroplasty.

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.

Clinical Outcomes and Complication Rates for Noncontiguous Anterior Cervical Discectomy and Fusion, Cervical Disc Arthroplasty, and Hybrid Cervical Surgery: A Systematic Review.

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.

Impact of Age on the Occurrence of Vascular Complications in Patients Undergoing Anterior Lumbar Approach Surgery.

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.

Reasons for Revision Surgery After Cervical Disk Arthroplasty Based on Medical Device Reports Maintained by the US Food and Drug Administration.

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.

Incidence and risk factors of heterotopic ossification after cervical Baguera C disc arthroplasty.

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.

Predictive Value of Cervical Degenerative Quantitative Scoring System on Postoperative Disc Height Loss After Cervical Disc Replacement.

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.

Anterior cervical discectomy and fusion versus cervical disc arthroplasty: an epidemiological review of 433,660 surgical patients from 2011 to 2021.

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.

Heterotopic ossification, osteolysis and implant failure following cervical total disc replacement with the M6-C™ artificial disc.

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.

Impact of Metabolic Syndrome on Early Postoperative Outcomes After Cervical Disk Replacement: A Propensity-matched Analysis.

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.

Comparing outcomes between anterior cervical disc replacement (ACDR) and minimally invasive posterior cervical foraminotomy (MI-PCF) in the treatment of cervical radiculopathy.

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.

Lumbar Total Disk Replacement Device Removals and Revisions Performed During a 20-Year Experience with 2141 Patients.

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.

Adjacent segment degeneration after single- and double-level cervical total disc replacement: a cohort with an over 12-year follow-up.

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.

Headache relief 10 years after cervical disc arthroplasty: multicenter randomized clinical trial post hoc analysis.

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.

Prospective, multicenter clinical trial comparing the M6-C compressible cervical disc with anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical radiculopathy: 5-year results of an FDA investigational device exemption study.

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.

Intervertebral (lumbar) disc replacement:the current state and future perspectives.

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.

Comparable long-term outcomes in patients undergoing total disc replacement or anterior cervical discectomy and noninstrumented fusion.

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.

Cervical disc arthroplasty with the Baguera C prosthesis: clinical and radiological results of a 10-year follow-up study.

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.