Long-term Results Comparing Cervical Disc Arthroplasty to Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Impact of Postoperative Dysphagia on Health Care Resource Utilization Following Single-Level Cervical Disc Arthroplasty

Study DesignRetrospective cohort study.ObjectivesThis study seeks to highlight differences in 1) postoperative complications, 2) recovery course, and 3) associated costs between patients with and without postoperative dysphagia who underwent single-level CDA.MethodsThe National Inpatient Sample (NIS) was queried to identify patients who underwent single-level CDA between 2016 and 2020. Patients were divided into dysphagia and control groups based on the presence or absence of postoperative dysphagia. Propensity score-matching (1:5) was performed, accounting for age, sex, race, and comorbidities. Primary outcomes included length of stay (LOS), hospital costs, and discharge disposition. Chi-square and t-tests were used for statistical comparisons. Significance was set at the P < .05 level.ResultsThe final analysis included 640 patients in the dysphagia group and 3,200 controls after matching. Patients in the dysphagia group experienced a significantly higher rate of perioperative complications (7.8% vs 2.8%; P = .006). The mean LOS was longer for the dysphagia group (2.9 ± .3 days vs 1.5 ± .1 days; P < .001), and hospitalization costs were significantly higher ($27,100 vs $21,700; P < .001). Additionally, dysphagia patients were more likely to have a non-routine discharge (15.6% vs 9.2%; P = .030).ConclusionsPostoperative dysphagia following CDA significantly escalates healthcare resource utilization, leading to prolonged hospital stays, increased costs, and a greater risk of non-routine discharge. This underscores the need for targeted interventions to reduce the incidence of dysphagia and improve recovery outcomes, ultimately enhancing patient care and reducing the financial burden on healthcare systems.

The Future of Arthroplasty in the Spine

The evolution of spinal arthroplasty, a significant journey that began in the 1960s and 1970s, has seen remarkable progress. Initially designed to preserve motion at spinal segments and avoid complications associated with fusion surgeries, early designs faced setbacks due to rudimentary concepts and limited materials. However, the 1980s marked a turning point with the development of modern total disc replacement concepts, utilizing advanced materials such as titanium and polyethylene to improve implant longevity and integration. The early 2000s saw crucial approvals by the U.S. Food and Drug Administration, leading to broader clinical adoption.By the 2010s, cervical disc arthroplasty (CDA) had been refined through innovations such as patient-specific implants and the integration of robotics and surgical navigation. Cervical disc arthroplasty and lumbar disc arthroplasty are effective alternatives to fusion, particularly in preserving motion and reducing adjacent segment disease. Ongoing research continues to focus on viscoelastic arthroplasty and the integration of biologics to enhance outcomes, providing reassurance about the continuous improvement in spinal arthroplasty and instilling optimism about its future.Selecting patients for arthroplasty is a critical process that requires careful consideration. Ideal candidates display symptoms unresponsive to conservative treatments, have adequate disc height, and possess good bone quality. As arthroplasty typically preserves motion, it is less suited for patients with severe joint diseases or significant spinal stiffness. This emphasis on patient selection underscores the need for thorough evaluation and the importance of considering individual patient factors.Despite its benefits, the adoption of disc arthroplasty faces barriers such as high costs, stringent inclusion criteria, and the need for specialized surgical training. Overcoming these barriers requires advocacy, improved training, and potentially revising inclusion criteria to ensure more patients can benefit from these advanced treatments. The future of spinal arthroplasty looks promising, with potential advancements in biokinetics, biomaterials, and the broader application of minimally invasive techniques. This ongoing evolution promises to improve clinical outcomes and significantly enhance patient quality of life, offering hope for a better future in spinal arthroplasty.

Surgical versus Nonsurgical Treatment for Cervical Radiculopathy

BACKGROUND

Cervical radiculopathy is typically caused by disc herniation or spondylosis. Few trials have compared the efficacy of surgical versus nonsurgical treatment for these conditions.

METHODS

We conducted two randomized clinical trials among 180 patients presenting to the Oslo University Hospital in Norway with disabling radicular arm pain and cervical disc herniation (trial 1; n=89) or spondylosis (trial 2; n=91) proven by magnetic resonance imaging or computerized tomography. Patients were randomly assigned in a 1:1 ratio to receive either surgical or nonsurgical treatment. Surgery involved anterior cervical discectomy and fusion. Nonsurgical treatment involved three sessions with physical medicine/rehabilitation physicians and three sessions with physiotherapists for functional and cognitive behavioral support. The primary outcome in both trials was the Neck Disability Index (NDI) score (range, 0 to 100; higher scores indicate greater disability; minimal important difference is 15) at 12 months, which was self-reported by the patients.

RESULTS

Among the 87 patients in the disc herniation trial with 12-month data (surgical group, n=45; nonsurgical group, n=42), the mean difference in NDI adjusted for baseline was 7.4 (95% confidence interval [CI], 1.6 to 13.3; P=0.01) in favor of surgical treatment. Among the 88 patients in the spondylosis trial with 12-month data (surgical, n=44; nonsurgical, n=44), the mean difference in NDI adjusted for baseline was 2.3 (95% CI, -4.9 to 9.6; P=0.52). In the disc herniation trial, two patients in the nonsurgical group crossed over to have surgery. In the spondylosis trial, 11 patients in the nonsurgical group crossed over to have surgery. There were no serious adverse events.

CONCLUSIONS

In patients with cervical radiculopathy, we found a statistically significant difference for NDI at 12 months in favor of surgical versus nonsurgical treatment in the disc herniation trial, but no difference in the spondylosis trial. (Funded by the Southern and Eastern Norway Regional Health Authority; HSØ#2017057; ClinicalTrials.gov number, NCT03674619.).

Complications and reoperations in young versus old patients undergoing cervical disc arthroplasty

Background

Despite the growing popularity of cervical disc arthroplasty (CDA), there remains a lack of literature investigating outcomes in older patients and no consensus exists on an age threshold beyond which CDA is not recommended. This study aimed to compare outcomes between patients younger than 65 and those aged 65 and older undergoing CDA.

Methods

Patients who underwent CDA at a major spine center (January 2009-December 2023), with at least 1 year of follow-up, were included. Two age-based cohorts were analyzed: younger (<65) and older (≥65). Both single and multilevel disc replacements were considered. Primary outcomes included comparing 90-day complications and all-cause reoperation rates in the 2 cohorts. Secondary outcomes included comparisons of patient characteristics, operative data, and length of stay (LOS). Frequencies, chi-squared analysis, and Student's t-test were used to compare cohorts.

Results

A total of 298 CDAs were evaluated among 188 patients. There were 132 patients in the younger cohort (mean age: 48.9±10.2) and 56 in the older cohort (mean age: 69.5±3.8). Cohorts were similar with regards to body mass index, sex, and length of follow up. The overall 90-day complication rate was 23.8%. There was no difference in complication rates (younger: 23.3%, older: 25.0%, p=.60). Older cohort averaged more levels operated (older 1.8±0.6, younger 1.5±0.7, p=.006). The overall reoperation rate was 12.2% (young: 13.5%, older: 8.9%, p=.38). Subsidence was the most common cause of reoperation in both the younger (n=4, 3.0%) and older (n=2, 3.6%) cohorts.

Conclusion

In this series, we found no statistically significant differences in 90-day complication or reoperation rates between younger (<65 years) and older (≥65 years) patients undergoing CDA. Subsidence emerged as the most common complication, occurring at similar rates in both cohorts. While further large-scale, long-term analysis is warranted to determine clinical outcomes of CDA in older patients, this study provides comparable complication and reoperation rates as in the younger population.

Cervical Disc Arthroplasties Fail to Maintain Physiological Kinematics Under Lateral Eccentric Loads

STUDY DESIGN

In vitro human cadaveric biomechanical analysis.

OBJECTIVES

Optimization of prostheses for cervical disc arthroplasties (CDA) reduces the risk of complications. The instantaneous helical axis (IHA) is a superior parameter for examining the kinematics of functional spinal units. There is no comprehensive study about the IHA after CDA considering all 3 motion dimensions.

METHODS

Ten human functional spinal units C4-5 (83.2 ± 7.9 yrs.) were examined with an established measuring apparatus in intact conditions (IC), and after CDA, with 2 different types of prostheses during axial rotation, lateral bending, and flexion/extension. Eccentric preloads simulated strains. The IHA orientation and its position at the point of rest (IHA0-position) were analyzed.

RESULTS

The results confirmed the existing data for IHA in IC. Lateral preloads showed structural alterations of kinematics after CDA: During axial rotation and lateral bending, the shift of the IHA0-position was corresponding with the lateral preloads' applied site in IC, while after CDAs, it was vice versa. During lateral bending, the lateral IHA orientation was inclined, corresponding with the lateral preloads' applied site in the IC and oppositely after the CDAs. During flexion/extension, the lateral IHA orientation was nearly vertical in the IC, while after CDA, it inclined, corresponding with the lateral preloads' applied site. The axial IHA orientation rotated to the lateral preloads' corresponding site in the IC; after CDA, it was vice versa.

CONCLUSION

Both CDAs failed to maintain physiological IHA characteristics under lateral preloads, revealing a new aspect for improving prostheses' design and optimizing their kinematics.

Are Patients With Segmental Cervical Kyphosis Appropriate Candidates for Cervical Disc Arthroplasty (CDA)? A Clinical and Radiographic Analysis Compared to Anterior Cervical Discectomy and Fusion (ACDF)

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To compare the clinical and radiographic outcomes of Anterior Cervical Discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) in patients with preoperative segmental kyphosis.

METHODS

Patients with segmental cervical kyphosis at the operative levels undergoing 1- or 2-level ACDF or CDA from 2017 to 2020 with 2 years of follow were identified. Patient demographics, perioperative data, complication rates, radiographic findings and reported outcomes were analyzed.

RESULTS

A total of 48 patients met inclusion criteria and were included in our study (ACDF: n = 24, CDA: n = 24). Patient demographic data between the 2 cohorts was similar expect for proportion of males (ACDF: 62.5% vs CDA: 33.3%, P = .043). There was no statistical significance in the change of segmental lordosis (ACDF: +8.09° vs CDA: +5.88°, P = .075) between the preoperative and final postoperative period. Additionally, the change in cervical lordosis was similar between groups (ACDF:+ 9.86° vs CDA: +7.60°, P = .226). VAS scores were similar between the 2 groups at every follow-up interval. NDI scores were significantly different at the 6-month, 12 month and the final follow-up. Mean improvements between preoperative and final postoperative periods were statistically superior in the CDA cohort compared to the ACDF cohort (ACDF: 22.8 vs CDA: 24.1, P = .0375).

CONCLUSION

CDA was superior to ACDF in regards to NDI scores following index procedure in patients with preoperative segmental cervical kyphosis. Those in the CDA cohort had similar complication rates, revision rates and radiographic outcomes as those who underwent ACDF.

Is Cervical Disc Arthroplasty an Effective Treatment for Cervical Degenerative Disease With Osteopenia?

STUDY DESIGN

Retrospective case-control study.

OBJECTIVES

To evaluate postoperative outcomes of single-level cervical disc arthroplasty (CDA) in patients with osteopenia and compare these results with a matched cohort of normal bone mineral density (BMD).

METHODS

Patients who had undergone single-level CDA were collected and screened. Included patients were divided into the osteopenia group and the normal group. 38 eligible patients with osteopenia were included in the final analysis. Subsequently, a 1:1 match was utilized. Clinical, radiographic data, and complications were recorded. Appropriate statistical methods were applied to conduct analysis using SPSS version 24.0.

RESULTS

The mean follow-up time was 30.5 ± 27.3 months. The osteopenia group achieved satisfactory clinical outcomes, with no significant intergroup differences. Additionally, there were no significant differences between groups in any of the radiological parameters, either in cervical alignment or segmental height, or range of motion. The radiological incidence rate of adjacent segmental degeneration and heterotopic ossification (HO) was comparable in both groups, respectively, with a similar composition of ROM-limiting HO. However, the osteopenia group had a tendency of more implant subsidence (2.7% vs 15.2%). The logistic regression analysis showed the osteopenia group had a significantly higher incidence rate of anterior bone loss (ABL) (OR = 5.37, 95% CI: 1.50 - 19.22).

CONCLUSIONS

Single-level CDA for patients with osteopenia achieved similar satisfactory clinical outcomes compared with the normal BMD group. Meanwhile, the osteopenia group maintained adequate sagittal balance and segmental height. Based on this observation, this option may be feasible for selected patients with osteopenia.

Operative Time Associated With Increased Length of Stay After Single-level Cervical Disk Arthroplasty: An Analysis of 3681 Surgeries

STUDY DESIGN

Level III evidence-retrospective cohort.

OBJECTIVE

The purpose of this study was to (1) determine whether longer CDA operative time increases the risk of 30-day postoperative complications, (2) analyze the association between operative time and subsequent health care utilization, and (3) discharge disposition.

BACKGROUND

Cervical disk arthroplasty (CDA) most commonly serves as an alternative to anterior cervical discectomy and fusion (ACDF) to treat cervical spine disease, however, with only 1600 CDAs performed annually relative to 132,000 ACDFs, it is a relatively novel procedure.

METHODS

A retrospective query was performed identifying patients who underwent single-level CDA between January 2012 and December 2018 using a nationwide database. Differences in baseline patient demographics were identified through univariate analysis. Multivariate logistic regression was performed to identify associations between operative time (reference: 81-100 min), medical/surgical complications, and health care utilization.

RESULTS

A total of 3681 cases were performed, with a mean patient age of 45.52 years and operative time of 107.72±49.6 minutes. Higher odds of length of stay were demonstrated starting with operative time category 101-120 minutes (odds ratio: 2.164, 95% CI: 1.247-3.754, P =0.006); however, not among discharge destination, 30-day unplanned readmission, or reoperation. Operative time <40 minutes was associated with 10.7x odds of nonhome discharge, while >240 minutes was associated with 4.4 times higher odds of LOS>2 days ( P <0.01). Increased operative time was not associated with higher odds of wound complication/infection, pulmonary embolism, deep venous thrombosis, or urinary tract infections.

CONCLUSIONS

Prolonged CDA operative time above the reference 81-100 minutes is independently associated with increased length of stay, but not other significant health care utilization parameters, including discharge disposition, readmission, or reoperation. There was no association between prolonged operative time and 30-day medical/surgical complications, including wound complications, infections, pulmonary embolism, or urinary tract infection.

Risk Factors for Reoperation Following Single-Level Cervical Disc Arthroplasty as Utilized in a Representative Sample of United States Clinical Practice: A Retrospective PearlDiver Study

STUDY DESIGN

Retrospective Cohort.

OBJECTIVES

Most data regarding cervical disc arthroplasty (CDA) outcomes are from highly controlled clinical trials with strict inclusion/exclusion criteria. This study aimed to identify risk factors for CDA reoperation, in "real world" clinical practice using a national insurance claims database.

METHODS

The PearlDiver database was queried for patients (2010-2020) who underwent a subsequent cervical procedure following a single-level CDA. Patients with less than 2 years follow-up were excluded. Primary outcome was to evaluate risk factors for reoperation. Secondary outcome was to evaluate the types of reoperations. Risk factors were compared using descriptive statistics. Multivariate regression analyses were used to ascertain the association among risk factors and reoperation.

RESULTS

Of 14,202 patients who met inclusion criteria, 916 (6.5%) underwent reoperation. Patients undergoing reoperation were slightly older with higher Elixhauser Comorbidity Index (ECI) scores, however both were not risk factors for reoperation. Patients with diagnoses such as smoking, myelopathy, inflammatory disorders, spinal deformity, trauma, or a history of prior cervical surgery were at greater risk for reoperation. No association was found between the year of index surgery and reoperation risk. The most common reoperation procedure was cervical fusion.

CONCLUSIONS

As billed for in the United States since 2010, CDA was associated with a 6.5% reoperation rate over a mean follow-up time of 5.3 years. Smoking, myelopathy, inflammatory disorders, spinal deformity, and a history of prior cervical surgery or trauma are risk factors for reoperation following CDA. Though patients who underwent a reoperation were older, age was not found to be an independent risk factor for a subsequent procedure.

Delayed Infection After Cervical Disc Arthroplasty: A Case Report and Review of the Literature

STUDY DESIGN

Case report and literature review.

OBJECTIVE

To report the relatively rare complication of delayed infection after cervical disc arthroplasty (CDA).

BACKGROUND

Delayed infection of the M6 device has been a rarely reported complication, with all cases described outside of the United States. The reliability of positive intraoperative cultures remains an ongoing debate.

METHODS

Cases were reviewed, and findings were summarized. A literature review was performed and discussed, with special consideration to current reports of delayed M6 infection, etiology, and utility of intraoperative cultures.

RESULTS

We present a case of delayed infection 6 years after primary 1-level CDA with the M6 device. At revision surgery, gross purulence was encountered. Intraoperative cultures finalized with Staphylococcus epidermidis and Cutibacterium acnes. The patient was revised with removal of the M6 and conversion to anterior cervical discectomy and fusion. A prolonged course of intravenous antibiotics was followed by an oral course for suppression. At the final follow-up, the patient's preoperative symptoms had resolved.

CONCLUSION

Delayed infection after CDA is a rare complication, with ongoing debate regarding the reliability of positive cultures. We describe an infected M6 and demonstrate the utility of implant removal, conversion to anterior cervical discectomy and fusion, and long-term antibiotics as definitive treatment.

LEVEL OF EVIDENCE

Level V-case report and literature review.

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.

Safety and Efficacy of Outpatient Anterior Cervical Disk Replacement (ACDR) in an Ambulatory Surgery Center Versus Hospital Setting: A 2-year Retrospective Analysis

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVE

To compare clinical outcomes of outpatient anterior cervical disk replacements (ACDR) performed in free-standing private ambulatory surgery centers versus tertiary hospital centers.

SUMMARY OF BACKGROUND DATA

ACDR is an increasingly popular technique for treating various degenerative pathologies of the cervical spine. There has been an increase in the utilization of ambulatory surgery centers (ASCs) for outpatient cervical procedures due to economic and convenience benefits; however, a paucity of literature exists in evaluating long-term safety and efficacy of ACDRs performed in ASCs versus outpatient hospital centers.

METHODS

A retrospective cohort review of all patients undergoing 1- or 2-level ACDRs at 2 outpatient ASCs and 4 tertiary care medical centers from 2012 to 2020, with a minimum follow-up of 24 months, was performed. Approval by each patient's insurance and patient preference determined distribution into an ASC or non-ASC. Demographics, perioperative data, length of follow-up, complications, and revision rates were analyzed. Functional outcomes were assessed using VAS and NDI at follow-up visits.

RESULTS

One hundred seventeen patients were included (65 non-ASC and 52 ASC). There were no significant differences in demographics or length of follow-up between the cohorts. ASC patients had significantly lower operative times (ASC: 89.5 minutes vs. non-ASC: 110.5 minutes, P <0.001) and mean blood loss (ASC: 17.5 mL vs. non-ASC: 25.3 mL, P <0.001). No significant differences were observed in rates of dysphagia (ASC: 21.2% vs. non-ASC: 15.6%, P <0.001), infection (ASC: 0.0% vs. non-ASC: 1.6%, P =0.202), ASD (ASC: 1.9% vs. non-ASC: 1.6%, P =0.202), or revision (ASC: 1.9% vs. non-ASC: 0.0%, P =0.262). Both groups demonstrated significant improvements in VAS and NDI scores ( P <0.001), but no significant differences in the degree of improvement were observed.

CONCLUSIONS

Our 2-year results demonstrate that ACDRs performed in ASCs may offer the advantages of reduced operative time and blood loss without an increased risk of postoperative complications.

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.

Influence of cervical total disc replacement on motion in the target and adjacent segments

BACKGROUND CONTEXT

The motion limitation after cervical discectomy and fusion alters the spine´s kinematics. Unphysiological strains may be the result and possible explanation for adjacent segment degeneration. Alterations to cervical kinematics due to cervical total disc replacement (TDR), especially two-level, are still under investigated.

PURPOSE

To investigate cervical motion including coupled motions after one-level and two-level TDR in the treated and also the adjacent segments.

STUDY DESIGN

An in-vitro study using pure moment loading of human donor spines.

METHODS

Seven fresh frozen human cervical spine specimens (C4-T1, median age 46 with range 19-60 years, four female) were included in this study. Specimens were tested in the intact condition first, followed by one-level TDR at C5-6 which was subsequently extended one level further caudal (C5-7). Each specimen was quasistatically loaded with pure moments up to 1.5 Nm in flexion/extension (FE), lateral bending (LB), and axial rotation (AR) in a universal spine tester for 3.5 cycles at 1 °/s. During the tests three dimensional motion tracking was performed for each vertebral body individually. From that, the primary and coupled ROM of each spinal level during the third full cycle of motion were evaluated. Nonparametric statistical analysis was performed using a Friedman-test and post hoc correction with Dunn-Bonferroni-tests (p<.05). Ethics approval was obtained in advance.

RESULTS

In FE, one-level TDR (C5-6) moderately increased primary FE in all four segments, but only significantly at the cranial adjacent level C4-5. Additional TDR at C6-7 further increased the ROM at the target segment without much influence on the other levels. Increasing implant height at C6-7 partially counteracted the increased FE. Coupled motions were minimal in all test conditions at all levels. In LB, coupled AR was observed in all test conditions at all levels. One-level TDR decreased primary LB at the target segment C5-6 significantly, without much influence on the other levels. Extending TDR to C6-7 decreased ROM in the target segment but without gaining statistical significance. Increasing implant height at C6-7 further decreased primary LB at the target segment, still without significance. Notably, coupled AR was significantly decreased at the cranial adjacent segment C4-5 compared to the intact condition. In AR, coupled LB was observed in all test conditions at the levels C4-5, C5-6, and C6-7, while the transition level to the thoracic spine C7-T1 showed only little coupled LB. Both one-level and two-level TDR showed little influence on primary AR or coupled motions at any level. Only after increasing implant height at C6-7 was the motion of the caudally adjacent level C7-T1 significantly altered.

CONCLUSION

Evaluating primary FE, LB, and AR together with the associated coupled motions revealed widespread influence of cervical TDR not only on the motion of the treated level but also at the adjacent segments. The influence of two-level TDR is more widespread and involves more levels than one-level TDR.

CLINICAL SIGNIFICANCE

The prevention of unphysiological strains due to altered kinematics after cervical fusion, which could possibly explain adjacent segment degeneration, were a driving factor in the development of TDR. These experimental findings suggest cervical TDR influences the whole cervical spine, not only the treated segment. The effect becomes more extensive, involving more levels and motion directions, after two-level than after one-level TDR.

Cervical Disc Arthroplasty (CDA) versus Anterior Cervical Discectomy and Fusion (ACDF) for Two-Level Cervical Disc Degenerative Disease: An Updated Systematic Review and Meta-Analysis

Background: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are both considered to be efficacious surgical procedures for treating cervical spondylosis in patients with or without compression myelopathy. This updated systematic review and meta-analysis aimed to compare the outcomes of these procedures for the treatment of cervical degenerative disc disease (DDD) at two contiguous levels. Methods: The PubMed, EMBASE, and Cochrane CENTRAL databases were searched up to 1 May 2023. Studies comparing the outcomes between CDA and ACDF in patients with two-level cervical DDD were eligible for inclusion. Primary outcomes were surgical success rates and secondary surgery rates. Secondary outcomes were scores on the Neck Disability Index (NDI) and Visual Analogue Scale (VAS) for neck and arm pain, as well as the Japanese Orthopaedic Association (JOA) score for the severity of cervical compression myelopathy and complication rates. Results: In total, eight studies (two RCTs, four retrospective studies, and two prospective studies) with a total of 1155 patients (CDA: 598; ACDF: 557) were included. Pooled results revealed that CDA was associated with a significantly higher overall success rate (OR, 2.710, 95% CI: 1.949-3.770) and lower secondary surgery rate (OR, 0.254, 95% CI: 0.169-0.382) compared to ACDF. In addition, complication rates were significantly lower in the CDA group than in the ACDF group (OR, 0.548, 95% CI: 0.326 to 0.919). CDA was also associated with significantly greater improvements in neck pain VAS than ACDF. No significant differences were found in improvements in the arm VAS, NDI, and JOA scores between the two procedures. Conclusions: CDA may provide better postoperative outcomes for surgical success, secondary surgery, pain reduction, and postoperative complications than ACDF for treating patients with two-level cervical DDD.

Cervical disc arthroplasty versus anterior cervical discectomy and fusion: an analysis of the Michigan Spine Surgery Improvement Collaborative Database

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are established surgical options for the treatment of cervical radiculopathy, myelopathy, and cervical degenerative disc disease. However, current literature does not demonstrate a clear superiority between ACDF and CDA.

PURPOSE

To investigate procedural and patient-reported outcomes of ACDF and CDA among patients included in the Michigan Spine Surgery Improvement Collaborative (MSSIC) database.

DESIGN

Retrospective study of prospectively collected outcomes registry data.

PATIENT SAMPLE

Individuals within the MSSIC database presenting with radiculopathy, myelopathy, or cervical spondylosis refractory to typical conservative care undergoing primary ACDF or CDA from January 4, 2016, to November 5, 2021.

OUTCOME MEASURES

Perioperative measures (including surgery length, length of stay, return to OR, any complications), patient-reported functional outcomes at 2-year follow-up (including return to work, patient satisfaction, PROMIS, EQ-5D, mJOA).

METHODS

Patients undergoing ACDF were matched 4:1 with those undergoing CDA; propensity analysis performed on operative levels (1- and 2- level procedures), presenting condition, demographics, and comorbidities. Initial comparisons performed with univariate testing and multivariate analysis performed with Poisson generalized estimating equation models clustering on hospital.

RESULTS

A total of 2,208 patients with ACDF and 552 patients with CDA were included. Baseline demographics were similar, with younger patients undergoing CDA (45.6 vs 48.6 years; p<.001). Myelopathy was more frequent in ACDF patients (30% vs 25%; p=.015). CDA was more frequently planned as an outpatient procedure. Length of stay was increased in ACDF (1.3 vs 1.0 days; p<.001). Functional outcomes were similar, with comparable proportions of patients meeting minimal clinically important difference thresholds in neck pain, arm pain, PROMIS, EQ-5D, and mJOA score. After multivariate regression, no significant differences were seen in surgical or functional outcomes.

CONCLUSIONS

This study demonstrates similar outcomes for those undergoing ACDF and CDA at 2 years. Previous meta-analyses of CDA clinical trial data adhere to strict inclusion and exclusion criteria required by clinical studies; this registry data provides "real world" clinical outcomes reflecting current practices for ACDF and CDA patient selection.

Restoration of Range of Motion in the Cervical Spine through Single-Segment Artificial Disc Replacement Using the Baguera®C Prosthesis

Background: Anterior cervical discectomy and fusion (ACDF) is a standard procedure for degenerative diseases of the cervical spine, providing nerve decompression and spinal stabilization. However, it limits cervical spine motility, restricts fused segment activity, and may lead to adjacent degeneration. Cervical disc arthroplasty (CDA) is an accepted alternative that preserves the structure and flexibility of the cervical spine. This study aimed to explore the dynamic changes in the range of motion (ROM) of the cervical spine after CDA using a viscoelastic artificial disc, as well as the factors affecting mobility restoration. Methods: A retrospective analysis was conducted on 132 patients who underwent single-level anterior cervical discectomy and CDA from January 2015 to June 2022. Result: Analysis of data from 132 patients revealed a significant improvement in clinical outcomes. The mean ROM of C2-C7 and functional spinal unit (FSU) segments significantly increased from 2 to 36 months post-operatively. Cervical spine flexibility was preserved and enhanced after prosthesis implantation. However, it took six months for the cervical spine motility to stabilize. In addition, sex and age were found to impact motility restoration, with female and younger patients exhibiting larger ROMs post-surgery. Additionally, CDA at the C5-C6 level resulted in the greatest increase in ROM, potentially improving overall kinematic ability. Conclusions: Single-segment artificial disc arthroplasty effectively restores the ROM in degenerative cervical spine conditions.

[Translated article] Less superior adjacent syndrome and lower reoperation rate. Medium- and long-term results of cervical arthroplasty versus anterior cervical arthrodesis: Systematic review and meta-analysis of randomized clinical trials

OBJECTIVE

To compare medium- and long-term postoperative surgical results, especially the adjacent syndrome rate, adverse event rate, and reoperation rate, of patients operated on with cervical arthroplasty or anterior cervical arthrodesis in published randomized clinical trials (RCTs), at one cervical level.

METHODS

Systematic review and meta-analysis. Thirteen RCTs were selected. The clinical, radiological and surgical results were analyzed, taking the adjacent syndrome rate and the reoperation rate as the primary objective of the study.

RESULTS

Two thousand nine hundred and sixty three patients were analyzed. The cervical arthroplasty group showed a lower rate of superior adjacent syndrome (P<0.001), lower reoperation rate (P<0.001), less radicular pain (P=0.002), and a better score of neck disability index (P=0.02) and SF-36 physical component (P=0.01). No significant differences were found in the lower adjacent syndrome rate, adverse event rate, neck pain scale, or SF-36 mental component. A range of motion of 7.91° was also found at final follow-up, and a heterotopic ossification rate of 9.67% in patients with cervical arthroplasty.

CONCLUSION

In the medium and long-term follow-up, cervical arthroplasty showed a lower rate of superior adjacent syndrome and a lower rate of reoperation. No statistically significant differences were found in the rate of inferior adjacent syndrome or in the rate of adverse events.

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.

Less superior adjacent syndrome and lower reoperation rate. Medium- and long-term results of cervical arthroplasty versus anterior cervical arthrodesis: Systematic review and meta-analysis of randomized clinical trials

OBJECTIVE

To compare medium- and long-term postoperative surgical results, especially the adjacent syndrome rate, adverse event rate, and reoperation rate, of patients operated on with cervical arthroplasty or anterior cervical arthrodesis in published randomized clinical trials (RCTs), at one cervical level.

METHODS

Systematic review and meta-analysis. Thirteen RCTs were selected. The clinical, radiological and surgical results were analyzed, taking the adjacent syndrome rate and the reoperation rate as the primary objective of the study.

RESULTS

Two thousand nine hundred and sixty three patients were analyzed. The cervical arthroplasty group showed a lower rate of superior adjacent syndrome (P<0.001), lower reoperation rate (P<0.001), less radicular pain (P=0.002), and a better score of neck disability index (P=0.02) and SF-36 physical component (P=0.01). No significant differences were found in the lower adjacent syndrome rate, adverse event rate, neck pain scale, or SF-36 mental component. A range of motion of 7.91 degrees was also found at final follow-up, and a heterotopic ossification rate of 9.67% in patients with cervical arthroplasty.

CONCLUSION

In the medium and long-term follow-up, cervical arthroplasty showed a lower rate of superior adjacent syndrome and a lower rate of reoperation. No statistically significant differences were found in the rate of inferior adjacent syndrome or in the rate of adverse events.

The move-C cervical artificial disc can restore intact range of motion and 3-D kinematics

BACKGROUND CONTEXT

In contrast to cervical discectomy and fusion, total disc replacement (TDR) aims at preserving the motion at the treated vertebral level. Spinal motion is commonly evaluated with the range of motion (ROM). However, more qualitative information about cervical kinematics before and after TDR is still lacking.

PURPOSE

The aim of this in vitro study was to investigate the influence of cervical TDR on ROM, instantaneous centers of rotation (ICR) and three-dimensional helical axes.

STUDY DESIGN

An in vitro study with human spine specimens under pure moment loading was conducted to evaluate the kinematics of the intact cervical spine and compare it to cervical TDR.

METHODS

Six fresh frozen human cervical specimens (C4-5, median age 28 years, range 19-47 years, two female and four male) were biomechanically characterized in the intact state and after implantation of a cervical disc prosthesis (MOVE-C, NGMedical, Germany). To mimic in vivo conditions regarding temperature and humidity, water steam was used to create a warm and humid test environment with 37°C. Each specimen was quasistatically loaded with pure moments up to ±2.5 Nm in flexion/extension (FE), lateral bending (LB) and axial rotation (AR) in a universal spine tester for 3.5 cycles at 1 °/s. For each third cycle of motion the ROM was evaluated and an established method was used to determine the helical axis and COR and to project them into three planar X-rays. Statistical analysis was conducted using a Friedman-test and post hoc correction with Dunn-Bonferroni-tests (p<.05).

RESULTS

After TDR, total ROM was increased in FE from 19.1° to 20.1°, decreased in LB from 14.6° to 12.6° and decreased in AR from 17.7° to 15.5°. No statistical differences between the primary ROM in the intact condition and ROM after TDR were detected. Coupled rotation between LB and AR were also maintained. The position and orientation of the helical axes after cervical TDR was in good agreement with the results of the intact specimens in all three motion directions. The ICR in FE and AR before and after TDR closely matched, while in LB the ICR after TDR were more caudal. The intact in vitro kinematics we found also resembled in vivo results of healthy individuals.

CONCLUSION

The results of this in vitro study highlight the potential of artificial cervical disc implants to replicate the quantity as well as the quality of motion of the intact cervical spine.

CLINICAL SIGNIFICANCE

Physiological motion preservation was a driving factor in the development of cervical TDR. Our results demonstrate the potential of cervical TDR to replicate in vivo kinematics in all three motion directions.

Should patient eligibility criteria for cervical disc arthroplasty (CDA) be expanded? A retrospective cohort analysis of relatively contraindicated patients undergoing CDA

BACKGROUND CONTEXT

Cervical disc arthroplasty (CDA) is a safe and effective alternative to anterior cervical discectomy and fusion (ACDF) in the treatment of various degenerative pathologies with advantages of motion preservation and lower rates of adjacent segment degeneration (ASD). Absolute contraindications for CDA have been well outlined in order to prevent adverse outcomes in patients. However, in cases of patients with relative contraindications (kyphotic deformity, prior cervical surgery, etc.), there remains controversy. There is minimal literature evaluating long-term outcomes in this patient population.

PURPOSE

To compare long-term clinical and functional outcomes of CDA in typical patients versus those with relative contraindications.

DESIGN

Retrospective cohort review.

PATIENT SAMPLE

Eighty-nine patients were included in the study: 55 (no contraindications) in Group 1 and 34 (relatively contraindicated) in Group 2 and 26 (preoperative segmental kyphosis) in Group 3.

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

Patients were placed in the relatively contraindicated cohort if they possessed at least one of the following: (1) segmental kyphosis of 5° to 10°, (2) significant loss of disc height (between 50% and 75% of initial measurements or 1.5-3mm), (3) bridging osteophytes, and (4) prior cervical spine surgery based on preoperative cervical radiographs. The other cohort included patients without any relative contraindication who underwent CDA over the same time frame. Additionally, a subgroup analysis was used to compare those without any contraindications to those with only preoperative segmental kyphosis. Patients were included in this study if they met the following criteria: over 18 years of age, minimum follow-up of 24 months, and availability of complete medical records. Patient demographics, levels operated on, and perioperative outcomes were assessed between the two groups. Revision and complication rates were recorded. Functional outcomes scores were compared using VAS and NDI scores at 6-months, 12-months and final follow-up.

RESULTS

Mean follow-up was 40.8 months in Group 1 and 38.3 months in Group 2 (p=.569). Complication rates were 21.8% in Group 1 and 26.4% in Group 2 (p=.615). Complication rates in a comparison between Groups 1 and 3 were statistically insignificant (p=.383). The most common complication was transient approach-related postoperative dysphagia (Group 1: 20% vs Group 2: 23.5%, p=.693). No significant differences were observed in the rates of transient dysphonia (Group 1: 0.0% vs Group 2: 2.9%, p=.201), adjacent segment degeneration (ASD) (Group 1: 1.8% vs Group 2: 0.0%, p=.429), infection (Group 1: 1.8% vs Group 2: 2.9%, p=.712), heterotopic ossification (Group 1: 49.1% vs Group 2: 50.0%, p=.934) or spontaneous fusion (Group 1: 1.8% vs Group 2: 2.9%, p=.728). No revision surgeries were observed in either cohort. All three groups demonstrated significant improvements in their VAS and NDI scores compared with preoperative measurements (p<.001), but no significant differences were found in the degree of improvement between groups at any point in time.

CONCLUSIONS

Our study found no significant differences in clinical and functional outcomes between patients undergoing 1- and 2-level CDA with relative contraindications versus typical patients. These findings suggest that patient eligibility criteria for CDA may warrant expansion. However, future prospective studies over a longer period of follow-up are necessary to corroborate our results.

Relative Efficacy of Cervical Total Disc Arthroplasty Devices and Anterior Cervical Discectomy and Fusion for Cervical Pathology: A Network Meta-Analysis

STUDY DESIGN

Systematic Review and Meta Analysis.

OBJECTIVE

This study sought to compare patient-reported outcomes, success, complications, and radiographic outcomes directly and indirectly between different cervical total disc arthroplasty (TDA) devices and anterior cervical discectomy and fusion (ACDF).

METHODS

Patients of prospective randomized controlled trials of 1-level cervical TDA with a minimum of 2 years follow up were identified in the literature. A frequentist network meta-analysis model was used to compare each outcome across the different TDA devices included and ACDF using the mixed effect sizes.

RESULTS

15 studies were included for quantitative analysis, reporting the outcomes of 2643 patients with an average follow-up was 67.3 months (range: 24-120 months), 1417 of whom underwent TDA and 1226 of whom underwent ACDF. Nine TDA devices were compared to ACDF, including the Bryan, Discover, Kineflex, M6, Mobi-C, PCM, Prestige ST, ProDisc-C, and Secure-C cervical prostheses. Several devices outperformed ACDF for certain outcomes, including Visual Analog Scale (VAS) Arm, Physical Component Score of the Short-Form Health Survey (SF PCS), neurological success, satisfaction, index-level secondary surgical interventions (SSI), and adjacent level surgeries. Cumulative ranking of each intervention assessed demonstrated the highest performance with the M6 prosthesis (P = .70), followed by Secure-C (P = .67), PCM (P = .57), Prestige ST (P = .57), ProDisc-C (P = .54), Mobi-C (P = .53), Bryan (P = .49), Kineflex (P = .49), Discover (P = .39), and ACDF (P = .14).

CONCLUSION

Cervical TDA was found to be superior on most outcomes assessed in the literature of high-quality clinical trials. While most devices demonstrated similar outcomes, certain prostheses such as the M6 were found to outperform others across several outcomes assessed. These findings suggest that the restoration of near-normal cervical kinematics may lead to improved outcomes.

Management Considerations for Total Intervertebral Disc Replacement

The burden of disease regarding lumbar and cervical spine pain is a long-standing, pervasive problem within medicine that has yet to be resolved. Specifically, neck and back pain are associated with chronic pain, disability, and exorbitant health care use worldwide, which have only been exacerbated by the increase in overall life years and chronic disease. Traditionally, patients with significant pain and disability secondary to disease of either the cervical or lumbar spine are treated via fusion or discectomy. Although these interventions have proved curative in the short-term, numerous longitudinal studies evaluating the efficacy of traditional management have reported severe impairment of normal spinal range of motion, as well as postoperative complications, including neurologic injury, radiculopathy, osteolysis, subsidence, and infection, paired with less than desirable reoperation rates. Consequently, there is a call for innovation and improvement in the treatment of lumbar and cervical spine pain, which may be answered by a modern technique known as intervertebral disc arthroplasty, or total disc replacement (TDR). Thus, this review aims to describe the management strategy of TDR and to explore updated considerations for its use in practice, both to help guide clinical decision making.

Biomechanics of Cervical Disk Replacement: Classifying Arthroplasty Implants

Cervical disk arthroplasty has been employed with increased frequency over the past 2 decades as a motion-preserving alternative to anterior cervical discectomy and fusion in select patients with myelopathy or radiculopathy secondary to degenerative disk disease. As indications continue to expand, an understanding of cervical kinematics and materials science is helpful for optimal implant selection. Cervical disk arthroplasty implants can be classified according to the mode of articulation and df , articulation material, and endplate construction. The incorporation of translational and rotational df allows the implant to emulate the dynamic and coupled centers of movement in the cervical spine. Durable and low-friction interfaces at the articulation sustain optimal performance and minimize particulate-induced tissue reactions. Endplate materials must facilitate osseous integration to ensure implant stability after primary fixation. These cardinal considerations underlie the design of the 9 implants currently approved by the FDA and serve as the foundation for further biomimetic research and development.

Short-term and Long-term Complications of Cervical Disc Arthroplasty

STUDY DESIGN

A narrative review.

OBJECTIVE

This review discusses the short and long-term complications associated with cervical disc arthroplasty (CDA).

SUMMARY OF BACKGROUND DATA

CDA is a safe and effective motion-sparing alternative to fusion for the treatment of cervical disc pathology in patients with cervical radiculopathy or myelopathy. Although CDA offers advantages over fusion within a narrower set of indications, it introduces new technical challenges and potential complications.

METHODS

A systematic search of several large databases, including Cochrane Central, PubMed, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry, was conducted from January 2005 to August 2023 to identify published studies and clinical trials evaluating cervical disc replacement complications and outcomes.

RESULTS

Short-term complications are primarily related to surgical approach and include dysphagia reported as high as ~70%, laryngeal nerve injury ~0%-1.25%, Horner syndrome ~0.06%, hematoma ~0.01%, gross device extrusion ~0.3%, whereas long-term complications include adjacent segment disease reported at ~3.8%, osteolysis ~44%-64%, heterotopic ossification ~7.3%-69.2%, implant failure ~3.3%-3.7%, and implant wear, which varies depending on design.

CONCLUSIONS

Approaches for mitigating complications broadly include meticulous dissection, intraoperative techniques, and diligent postoperative follow-up. This review emphasizes the need for a comprehensive understanding and management of complications to enhance the safety, reproducibility, and success of CDA. As CDA continues to evolve, there remains a critical need for ongoing research to delve deeper into evaluating risk for complications and long-term patient outcomes.

Cervical Disc Arthroplasty for the Treatment of Noncontiguous Cervical Degenerative Disc Disease: Results of Mid- to Long-Term Follow-up

OBJECTIVE

The long-term results of cervical disc arthroplasty (CDA) for noncontiguous cervical degenerative disc disease (CDDD) are still uncertain. Moreover, it is unclear whether CDA delays or avoids the degeneration of the intermediate segment (IS), leading to controversy in the field. Therefore, this study aimed to investigate the mid- to long-term clinical and radiographic outcomes of CDA in treating noncontiguous CDDD and to explore whether the IS degenerated faster after CDA than other non-surgically treated adjacent segments.

METHODS

We retrospectively analyzed patients with noncontiguous CDDD who underwent CDA in our department between January 2008 and July 2018. The patients were divided into the CDA and hybrid surgery (HS) groups, and clinical and radiographic outcomes were evaluated at routine postoperative intervals. Clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA), neck disability index (NDI), and visual analogue scale (VAS), while radiographic outcomes included cervical lordosis (CL), C2-C7 range of motion (ROM), segmental ROM, and disc angle (DA) at the arthroplasty level. Complications were also evaluated.Pre- and postoperative values were compared using paired t-tests or Wilcoxon rank-sum tests. Independent Student t-tests or Mann-Whitney U tests analyzed continuous data between CDA and HS groups, while chi-square or Fisher exact tests assessed categorical data.

RESULTS

Sixty-four patients with noncontiguous CDDD, with 31 in the CDA group and 33 in the HS group, were evaluated. The mean follow-up time was over 70 months. The most frequently involved levels were C4/5 and C5/6. Both groups showed significant improvements in JOA, NDI, and VAS values after surgery. Although CL was maintained, the CL in the CDA group was consistently lower than that in the HS group (p < 0.05). There was a significant decrease in C2-C7 ROM (p < 0.05), but at the last follow-up, the C2-C7 ROM in the CDA group was greater than that in the HS group (p < 0.05). At the last follow-up, 44.3% of arthroplasty levels had developed heterotopic ossification (HO), and 48.45% had developed anterior bone loss (ABL). In addition, adjacent segment degeneration (ASDeg) was observed in the IS (22.7%), superior adjacent segment (20.6%)and inferior adjacent segment (21.9%).

CONCLUSION

CDA or CDA combined with fusion are viable treatments for noncontiguous CDDD, with satisfactory outcomes after mid-to-long-term follow-up. ASDeg is similar in non-surgical segments after 70 months of follow-up. ROM of the IS issimilar to preoperative levels, indicating CDA does not increase the risk of IS degeneration.

Cervical Disc Arthroplasty Usage Has Leveled Out From 2010 to 2021

STUDY DESIGN

Descriptive epidemiologic study.

OBJECTIVE

To compare trends in utilization and predictive factors for single-level cervical disc arthroplasty (CDA) relative to anterior cervical discectomy and fusion (ACDF) over the years.

BACKGROUND

CDA is an alternative to ACDF for the treatment of cervical spine pathologies. With both procedures performed for similar indications, controversy on best practices exists.

MATERIALS AND METHODS

Patients who underwent single-level CDA or ACDF were identified in the 2010 through 2021 PearlDiver M151Ortho data set. The yearly number of CDAs performed and proportionality was assessed. Predictive patient factors for undergoing CDA as opposed to ACDF were determined. Kaplan Meyer survival analysis with an endpoint of cervical spine reoperation compared 5-year outcomes between CDA and ACDF.

RESULTS

From 2010 to 2021, 19,301 single-level CDAs and 181,476 single-level ACDFs were identified. The proportional utilization of CDA relative to ACDF increased from 4.00% in 2010 to 14.15% in 2018 ( P < 0.0001), after which there was a plateau between 2018 and 2021 where proportional utilization was 14.47% ( P = 0.4654). Multivariate analysis identified several predictors of undergoing CDA rather than ACDF, including: younger age [odds ratio (OR) per decade decrease: 1.72], having surgery performed in the Midwest, Northeast, or West (relative to South, OR: 1.16, 1.13, 2.26, respectively), having Commercial insurance (relative to Medicare, OR: 1.75), and having surgery performed by an orthopedic surgeon (relative to a neurological surgeon, OR: 1.54) ( P < 0.0001 for each). There was no statistically significant difference in 5-year survival to further cervical spine surgery between CDA and ACDF at 5 years (97.6% vs. 97.7%, P = 0.4249).

CONCLUSIONS

Although the use of CDA relative to ACDF rose from 2010 to 2018, its use has subsequently plateaued between 2018 and 2021 and remained a relatively low percentage of the single-level anterior cervical surgeries performed (14.47% in 2021). The causes for such changes in the trend are unclear.

Hybrid fixation versus conventional cage-plate construct in 3-level ACDF: Introduce the "seesaw theory" of stand-alone cage

STUDY DESIGN

A retrospective study.

BACKGROUND

Conventional cage-plate construct (CCP) was widely used in anterior cervical discectomy and fusion (ACDF), but the rigid fixation limits the motion of fused segments. Self-locking stand-alone cage (SSC) was an alternative for ACDF procedures and showed several superiorities. However, the effect of hybrid fixation in 3-level ACDF remains unknown.

OBJECTIVE

To assess the clinical and radiological outcomes of hybrid fixation with SSC and CCP against conventional CCP in 3-level ACDF.

METHOD

A retrospective review of patients who underwent 3-level ACDF at Renji Hospital between January 2018 and December 2019 was performed. Eighty-three patients met the inclusion and exclusion criteria and were stratified into 2 groups based on the fixation methods. The clinical outcomes, functional outcomes, and radiological parameters were collected and analyzed.

RESULTS

No significant difference was observed between the two groups in the mean age, sex, body mass index, hospital stay, and duration of follow-up. The postoperative C2-7 Cobb angle in the CCP group was significantly greater than that in the hybrid group. The rate of cervical proximal junctional kyphosis (CPJK) in the hybrid group was significantly lower than that in the CCP group. The CCP group suffered significantly higher rates of adjacent segment degeneration (ASD) than the hybrid group at 2 years postoperatively. Moreover, the incidence of postoperative dysphagia was lower in the hybrid group. No significant differences were observed in JOA and NDI scores between the two groups.

CONCLUSION

The hybrid fixation achieved comparable clinical outcomes against CCP fixation, indicating that hybrid fixation is an alternative procedure in 3-level ACDF.

Disc prosthesis versus fusion with cage in single level cervical degenerative spine disease - A retrospective case-control patient reported outcome study

AIM

To compare the clinical outcome of single level cervical degenerative spine disease treated surgically with motion preserving anterior cervical disc arthroplasty versus anterior cervical discectomy and fusion (ACDF).

METHODS

Patients treated with cervical disc arthroplasty at Aalborg University Hospital and ACDF at Aarhus University Hospital were matched 1:2. Primary outcome measures were Neck Disability Index (NDI), EQ-5D-3 L and Numeric rating scale (NRS) for arm- and neck pain. Data was collected by telephone interviews regarding present and retrospective data.

RESULTS

50 patients treated with cervical disc arthroplasty were matched to 100 ACDF patients covering November 2011 to December 2018. Mean improvements for NRS neck pain three-months postoperative, and NDI were significantly better in the cervical disc arthroplasty group, with intergroup differences of 1.56 (p = 0.02) and 5.01 (p = 0.01) respectively. A subgroup analysis of the half of the cohort with the longest follow-up (mean 7.6 years) showed, in favour of cervical disc arthroplasty, mean improvements of NDI: 8.80 (p = 0.00), EQ5D: - 0.19 (p = 0.04), NRS neck three months follow-up: 3.70 (p = 0.00) and long follow-up: 2.54 (p = 0.01) and NRS arm three months follow-up: 2.02 (p = 0.01). Radiologic examination indicated preserved mobility in 80% of the implanted protheses at 24-month post-surgical follow-up.

CONCLUSION

Surgical treatment of one level degenerative cervical spine disease with cervical disc arthroplasty or anterior cervical discectomy and fusion has a similar good clinical outcome after a mean follow-up of 5.6 years. However, cervical disc arthroplasty displayed long-term superiority in the half of the cohort with the longest follow-up time averaging 7.6 years.

Incidence and Risk Factor of Implant Dislocation After Cervical Disk Arthroplasty: A Retrospective Cohort Analysis of 756 Patients

BACKGROUND

Implant dislocation after cervical disk arthroplasty (CDA) is obviously a critical complication, but no information about the incidence and associated risk factor has been reported.

OBJECTIVE

To investigate the incidence and risk factor of implant dislocation after CDA by a retrospective cohort analysis.

METHODS

A retrospective review of a consecutive series of CDA performed between January 2009 and March 2021 at a single institution was conducted. Analyses of chart records and radiological data established the incidence and associated risk factor of implant dislocation after CDA. A Kaplan-Meier survival estimation of implant survival was performed.

RESULTS

A total of 756 consecutive patients were included in this analysis. Five patients (0.7%) had a migration and even dropout of the artificial disk. The overall cumulative survival rate of the implant reached approximately 99.3% of the 756 patients. Preoperative kyphosis was significantly related to implant dislocation ( P = .016), with an odds ratio of 15.013.

CONCLUSION

The incidence of implant dislocation after CDA is as low as 0.7% or 5/756 patients. Preoperative kyphosis significantly increases the risk of postoperative implant dislocation by a factor of 15. The migrating implants could be revealed on radiographs as early as 0.9 to 1.4 months postoperatively and were revised to anterior cervical diskectomy and fusion within half a year. No new event of implant dislocation occurred half a year postoperatively. The overall cumulative survival rate of the implant reached 99.3% of the 756 patients. In conclusion, CDA remains a safe and reliable procedure.

Restore cervical sagittal alignment by cervical disc arthroplasty and systematic total bilateral uncuscectomy in severe spondylosis: A prospective study

Introduction

Severe spondylosis is common and represents contraindication to achieve cervical disc arthroplasty (CDA).

Research question

Is it possible to restore cervical sagittal alignment using an adequate prosthetic model and performing systematic bilateral total uncuscectomy (or uncinectomy), even in cases of severe spondylosis ?

Material and methods

We propose a prospective clinical and radiological study comparing the evolution of preoperative and postoperative cervical sagittal balance 1 year after the interposition of a prosthesis with mobile bearing and systematic total uncuscectomy. VAS for brachialgia and cervicalgia, NDI, Odom's criteria, C2-C7 Cobb angle, C2-C7 SVA, T1 slope, C2 slope, C1-C2 Cobb angle, and segmental Cobb angle were analyzed preoperatively and 1 year postoperatively.

Results

73 patients for a total of 129 levels treated were analyzed. Patients showed significant improvements in VASb, VASc, NDI, and Odom's criteria one year after surgery without clinical differences in the severe spondylosis subgroup (41 patients for 77 levels treated). Our results showed an increase in the C2-C7 Cobb angle postoperatively and a better correlation between T1 slope and C2-C7 Cobb angle postoperatively than preoperatively. Postoperative radiological results were similar between the spondylosis and non-spondylosis subgroups. However preoperative C2-C7 Cobb angle and preoperative ROM were lower in the severe spondylosis subgroup.

Discussion and conclusion

This study showed the possibility of restoring cervical sagittal balance by performing cervical disc arthroplasty with systematic uncuscectomy, even in cases of severe spondylosis. Moreover, we propose a simplified mathematical formula to preoperatively evaluate the lack of angulation to restore sagittal cervical alignment.

Mechanical characterization of a novel biomimetic artificial disc for the cervical spine

A novel biomimetic artificial intervertebral disc (bioAID) replacement implant has been developed containing a swelling hydrogel representing the nucleus pulposus, a tensile strong fiber jacket as annulus fibrosus and titanium endplates with pins to primarily secure the device between the vertebral bodies. In this study, the design safety of this novel implant was evaluated based on several biomechanical parameters, namely compressive strength, shear-compressive strength, risk of subsidence and device expulsion as well as identifying the diurnal creep-recovery characteristics of the device. The bioAID remained intact up to 1 kN under static axial compression and only 0.4 mm of translation was observed under a compressive shear load of 20 N. No subsidence was observed after 0.5 million cycles of sinusoidal compressive loading between 50 and 225 N. After applying 400 N in antero-posterior direction under 100 N axial compressive preload, approximately 2 mm displacement was found, being within the range of displacements reported for other commercially available cervical disc replacement devices. The diurnal creep recovery behavior of the bioAID closely resembled what has been reported for natural intervertebral discs in literature. Overall, these results indicate that the current design can withstand (shear-compression loads and is able to remain fixed in a mechanical design resembling the vertebral bodies. Moreover, it is one of the first implants that can closely mimic the poroelastic and viscoelastic behavior of natural disc under a diurnal loading pattern.

Cervical disc arthroplasty with systematic total bilateral uncuscectomy - Adapted technique particularly in severe spondylosis: A prospective study

Introduction

Cervical disc arthroplasty (CDA) is mainly used in young patients with soft herniated discs and seems to have several advantages over anterior cervical discectomy and fusion (ACDF). Severe spondylosis is common and represents a contraindication for performing CDA.

Research question

Is it possible to expand the indications for the implantation of cervical prostheses by adapting the surgical technique, particularly for severe spondylosis, to benefit from the advantages of prostheses over ACDF ?

Materials and methods

We propose a prospective two-center study to compare the possible clinical benefit of the placement of a cervical prosthesis with systematic total bilateral uncuscectomy (or uncinectomy) compared to the classical technique of ACDF, particularly for severe spondylosis. Visual analog scales for brachialgia, cervicalgia, and neck disability index were measured before and one year after surgery. Odom's criteria were assessed one year after surgery.

Results

We compared 81 patients treated with CDA and systematic total bilateral uncuscectomy versus 42 patients treated with ACDF for symptomatic radicular or medullary compression. Patients treated with CDA and uncuscectomy showed greater improvements in VASb, VASc, NDI, and Odom's criteria than those treated with ACDF, with statistically significant results. Moreover, no difference was found between the severe spondylosis subgroup and the non-severe spondylosis subgroup treated with CDA and uncuscectomy.

Discussion and conclusion

This study assessed the value of systematic total bilateral uncuscectomy for cervical arthroplasty. Our prospective clinical results suggest a surgical technique to reduce cervical pain and improve function one year after surgery, even in cases of severe spondylosis.

Cervical Disk Arthroplasty and Range of Motion at 7 Years: Impact on Adjacent Level Degeneration

STUDY DESIGN

Secondary analysis of data collected in a prospective, randomized, noninferiority Food and Drug Administration (FDA) Investigational Device Exemption (IDE) clinical trial.

OBJECTIVE

The objective of this study was to evaluate the impact of range of motion (ROM) following single-level cervical disk arthroplasty (CDA) on the development of radiographic adjacent level degeneration (ALD).

SUMMARY OF BACKGROUND DATA

The rationale for CDA is that maintenance of index-level ROM will decrease adjacent level stresses and ultimately reduce the development of ALD compared with anterior cervical discectomy and fusion. However, little information is available on the impact of hypermobility on the development of ALD after CDA.

MATERIALS AND METHODS

Radiographic assessments were evaluated for index-level flexion-extension ROM and ALD. Continuous data was assessed using 1-way analysis of variance. The relationship between ALD progression and ROM was evaluated using χ 2 tests. The α was set at 0.05.

RESULTS

More ALD progression was observed after anterior cervical discectomy and fusion than CDA ( P =0.002 at the superior and P =0.049 at the inferior level). Furthermore, there was an association between ALD progression and ROM ( P =0.014 at the superior level and P =0.050 at the inferior level) where patients with mid-ROM after CDA experienced the lowest frequency of ALD progression at the superior and inferior levels. Patients with the lowest and highest ROM after CDA experienced a greater increase in ALD score at the inferior level ( P =0.046). Sex and age were associated with ROM groups ( P =0.001 and 0.023, respectively).

CONCLUSIONS

While maintenance of index-level ROM is protective after CDA, patients with the highest ROM after CDA have similar rates of ALD progression to the lowest ROM and greater increases in ALD compared with mid-ROM after CDA. High ROM after CDA may contribute to ALD progression.

Cervical Total Disc Replacement and Anterior Cervical Discectomy and Fusion: Comparison of 30-Day Population Comorbidities and Perioperative Complications Using 6 Years of American College of Surgeons National Surgical Quality Improvement Program Participant Use File Data

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 χ2 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.

Cervical Radiculopathy Impact Scale: Translation, cross-cultural adaptation, reliability and validity of the Turkish version

Objectives

The aim of this study was to translate and cross-culturally adapt the English version of the Cervical Radiculopathy Impact Scale (CRIS) and to investigate the validity and reliability of the Turkish version of the CRIS.

Patients and methods

Between October 2021 and February 2022, a total of 105 patients (48 males, 57 females; mean age: 45.4±11.8 years; range, 36.5 to 55.5 years) who were diagnosed with cervical radiculopathy due to disc herniation were included. Disability and quality of life were evaluated with the Neck Disability Index (NDI), Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), and Short Form-12 (SF-12). Pain severity was evaluated using the Numerical Rating Scale (NRS) in three subscales (neck pain, pain radiating to the arm, and numbness in the finger, hand, or arm). The internal consistency for CRIS was assessed using the Cronbach alpha and test-retest reliability by intraclass correlation coefficients (ICCs). Explanatory factor analyses were performed for construct validity. To examine the content validity, the correlations among the three subgroup scores of CRIS and the other scale scores were analyzed.

Results

The internal consistency of CRIS was found to be high (α=0.937). A high reliability was obtained for test-retest reliability for the three subscales of CRIS (Symptoms, Energy and postures, Actions and activities) (ICC: 0.950, 0.941, 0.962, respectively; p<0.001). All three subscale scores of CRIS were correlated with the NDI, QuickDASH, SF-12 (physical and mental) and NRS scores (r=0.358-0.713, p<0.001). Factor analysis showed that the scale had five factors.

Conclusion

The CRIS is a valid and reliable instrument for Turkish patients with cervical radiculopathy due to disc herniation.

Cervical Disk Arthroplasty: Surgical Technique

PURPOSE

Cervical disk arthroplasty (CDA) has emerged as a promising alternative to anterior cervical discectomy and fusion for the management of cervical disk degeneration causing neurological symptoms. This manuscript and accompanying digital content demonstrate the senior author's preferred surgical technique for a single-level CDA.

METHODS

CDA is performed using a standard, left-sided Smith Robinson approach. A complete discectomy is performed, with resection of the posterior longitudinal ligament and decompression of the neuroforamina bilaterally. Careful endplate preparation and trial is performed, and the final implant is impacted under a combination of direct visualization and fluoroscopy. Postoperatively, a soft collar is worn for comfort, and the patient is discharged on postoperative day 1 or 2.

RESULTS

This video, Supplemental Digital Content 1, http://links.lww.com/CLINSPINE/A254 presents the case of a 43-year old woman with mild cervical spondylosis with a paracentral disk herniation causing left C6 radiculopathy refractory to conservative measures. A C5-6 cervical disk arthroplasty was performed.

CONCLUSIONS

CDA presents a motion-sparing alternative to anterior cervical discectomy and fusion and has the potential to reduce adjacent segment disease, though further studies are needed to fully determine its benefits and expanding indications. Careful patient selection and proper surgical technique, as demonstrated here, remain crucial in optimizing outcomes.

Segmental range of motion after cervical total disc arthroplasty at long-term follow-up: a systematic review and meta-analysis

OBJECTIVE

As an alternative procedure to anterior cervical discectomy and fusion, total disc arthroplasty (TDA) facilitates direct neural decompression and disc height restoration while also preserving cervical spine kinematics. To date, few studies have reported long-term functional outcomes after TDA. This paper reports the results of a systematic review and meta-analysis that investigated how segmental range of motion (ROM) at the operative level is maintained with long-term follow-up.

METHODS

PubMed and MEDLINE were queried for all published studies pertaining to cervical TDA. The methodology for screening adhered strictly to the PRISMA guidelines. All English-language prospective studies that reported ROM preoperatively, 1 year postoperatively, and/or at long-term follow-up of 5 years or more were included. A meta-analysis was performed using Cochran's Q and I2 to test data for statistical heterogeneity, in which case a random-effects model was used. The mean differences (MDs) and associated 95% confidence intervals (CIs) were reported.

RESULTS

Of the 12 studies that met the inclusion criteria, 8 reported the long-term outcomes of 944 patients with an average (range) follow-up of 99.86 (60-142) months and were included in the meta-analysis. There was no difference between preoperative segmental ROM and segmental ROM at 1-year follow-up (MD 0.91°, 95% CI -1.25° to 3.07°, p = 0.410). After the exclusion of 1 study from the comparison between preoperative and 1-year ROM owing to significant statistical heterogeneity according to the sensitivity analysis, ROM significantly improved at 1 year postoperatively (MD 1.92°, 95% CI 1.04°-2.79°, p < 0.001). However, at longer-term follow-up, the authors again found no difference with preoperative segmental ROM, and no study was excluded on the basis of the results of further sensitivity analysis (MD -0.22°, 95% CI -1.69° to -1.23°, p = 0.760). In contrast, there was a significant decrease in ROM from 1 year postoperatively to final long-term follow-up (MD -0.77°, 95% CI -1.29° to -0.24°, p = 0.004).

CONCLUSIONS

Segmental ROM was found to initially improve beyond preoperative values for as long as 1 year postoperatively, but then ROM deteriorated back to values consistent with preoperative motion at long-term follow-up. Although additional studies with further longitudinal follow-up are needed, these findings further support the notion that cervical TDA may successfully maintain physiological spinal kinematics over the long term.

Cervical Alignment Analysis Comparing Two-Level Cervical Disc Arthroplasty with Anterior Cervical Discectomy and Fusion with Anterior Plate Fixation

OBJECTIVE

This study assesses cervical alignments after 2-level cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) with anterior plate fixation.

METHODS

Eighty-two patients who underwent 2-level CDA or ACDF in 2014-2019 were identified. Cervical alignment parameters were compared between the 2 cohorts. Subgroup analyses were performed to determine factors that differentiate alignment outcomes between the 2 procedures.

RESULTS

Although both cohorts achieved significant focal lordosis (FL) and overall cervical lordotic (CL) gains, CDA cohorts achieved significantly greater 12-month FL gain (P = 0.022). However, in a multivariate analysis controlling for preoperative variables, FL gain was no longer significant. Although the CDA cervical sagittal vertical axis (cSVA) significantly improved at 3 (P = 0.030) and 12 (P = 0.007) months, these improvements were not superior to the ACDF cSVA. Male patients undergoing CDA achieved greater 12-month CL gain. Patients undergoing CDA with body mass index >25 kg/m² achieved greater 12-month FL gain. Patients undergoing CDA with symptom duration >12 months achieved greater FL gain at 3 and 12 months. Patients undergoing CDA with high baseline T1 slope or cSVA achieved greater 12-month cSVA reduction. Clinical outcomes were comparable between the 2 cohorts. Unlike the ACDF group, CL gain in the CDA group was significantly correlated with the cSVA reduction, which was associated with significant improvement in the Neck Disability Index, arm pain, and 12-Item Short-Form Mental Component Scores. Heterotopic ossification was not found to significantly affect patient outcome and cervical alignment in both cohorts.

CONCLUSIONS

ACDF and CDA are viable options for 2-level degenerative disc disease in carefully selected patients. Both approaches produced equivalent postoperative alignment changes in a 2-level operation.

Early Experiences of One-Level Total Disc Replacement (Prestige LP) in Japan: A Comparison of Short-Term Outcomes with Anterior Cervical Discectomy with Fusion

Introduction

In Japan, cervical total disc replacement (TDR) was approved in 2017. However, because of its short history, no comparative study between cervical TDR and anterior cervical discectomy with fusion (ACDF) has been conducted in the country. Therefore, we examined and compared the surgical outcomes of TDR and ACDF for one-level cervical degenerative diseases.

Methods

In total, 50 patients who had received anterior surgeries for one-level cervical degenerative diseases were investigated. Among them, 25 underwent TDR (Prestige LP; Medtronic), whereas the other 25 patients underwent ACDF. ACDF samples were selected from cases conducted before the approval of TDR (-2017.9) and were retrospectively judged to be indicated for TDR. Before and at 1 year after surgery, clinical and radiological outcomes were evaluated.

Results

No significant differences in terms of patient demographics between the two groups were observed. A longer operative time was observed in the TDR group than in the ACDF group. Postoperatively, no differences in the Japanese Orthopaedic Association score for cervical myelopathy (C-JOA) score, neck pain visual analog scale, C2-7 angle, and C2-7 range of motion (ROM) were determined. TDR tended to show better neck disability index (NDI) scores postoperatively when compared with ACDF. The local angle at operative level was larger in ACDF. In TDR, the local ROMs were maintained postoperatively; however, in ACDF, the local ROM at the operative level was decreased, and the local ROMs at adjacent levels were increased postoperatively. In the TDR group, although heterotopic ossification was observed in 11 patients (44.0%), and anterior bone loss was identified in 14 patients (56.0%), these issues did not affect surgical outcomes.

Conclusions

Conclusively, no differences in terms of C-JOA score and neck pain between patients treated through TDR and ACDF were observed. However, a trend of better NDI scores was identified with TDR. While TDR maintained postoperative ROMs, ACDF showed an increase in the local ROMs at adjacent levels.

Surgical Treatment of Single Level Cervical Radiculopathy: A Comparison of Anterior Cervical Decompression and Fusion (ACDF) Versus Cervical Disk Arthroplasty (CDA) Versus Posterior Cervical Foraminotomy (PCF)

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

The objective of this study is to retrospectively compare the clinical outcomes, complication rates, and reoperation rates among the 4 treatments in patients with cervical radiculopathy.

SUMMARY OF BACKGROUND DATA

Surgical options for cervical radiculopathy include anterior cervical discectomy and fusion (ACDF), open posterior cervical foraminotomy (O-PCF), minimally invasive posterior cervical foraminotomy (MI-PCF), and cervical disk arthroplasty (CDA).

MATERIALS AND METHODS

Retrospective chart review after Review Board approval. Of the 384 patients in the study-257 ACDF, 18 O-PCF, 52 MI-PCF, and 56 CDA. Information was obtained from the charts and compared between the groups.

PATIENT SAMPLE

Patients above 18 years of age with single-level, unilateral cervical radiculopathy correlating with magnetic resonance imaging, failure of nonoperative management, and 1-level ACDF, O-PCF, MI-PCF, or CDA with >24 months of follow-up.

OUTCOME MEASURES

Neck Disability Index (NDI), Visual Analog Score neck and arm pain, minimum clinically significant difference (MCID), complication rates, and reoperation rates.

RESULTS

Operative time was significantly shorter for MI-PCF. Median estimated blood loss was small, but greater with O-PCF compared with other interventions. The length of hospital stay was longest for the ACDF group. At 2 years' follow-up, 36 subjects (9%) had subsequent neck surgery. The most common indication for additional surgery was recurrent symptoms (3.4%) followed by adjacent segment disease (2.6%), pseudoarthrosis (2.1%), adjacent segment disease + pseudoarthrosis (0.5%), and implant-related complications (0.3%). There was no statistically significant difference in complication rates between groups. MCID in NDI was achieved in 40% of MI-PCF subjects, 42% of O-PCF subjects, 66% of CDA subjects and 46% of ACDF subjects.

CONCLUSIONS

All 4 treatment options confer good clinical results on patients for cervical radiculopathy. Intraoperative and postoperative complications were low and comparable in all 4 groups. MI-PCF had the shortest surgical time and length of hospital stay. More CDA patients achieved MCID in NDI compared with the others, and the rate for additional surgery at 2 years was lowest in the CDA group.

Cervical Total Disk Replacement: Available Implant Size Matters

STUDY DESIGN

This study was a post hoc analysis of data collected from 2 Food and Drug Administration (FDA) Investigational Device Exemption (IDE) trials.

OBJECTIVE

The purposes of this study were to: (1) measure disk space heights adjacent to the level to be treated with a total disk replacement (TDR); (2) analyze cervical disk space heights to be replaced with TDR; and (3) investigate the frequency of use of a smaller height TDR when available.

SUMMARY OF BACKGROUND DATA

Cervical TDR produces outcomes noninferior or superior to anterior cervical discectomy and fusion. While the restoration of the height of a collapsed, degenerated disk is a surgical goal, there are potential problems with overdistracting the segment with an implant.

METHODS

Disk heights were measured using radiographs from the 1-level Simplify Cervical Artificial Disk IDE trial, producing values for 259 levels adjacent to the treated level and 162 treated levels. The device is available in 4, 5, and 6 mm heights. The 4 mm height became available only after treatment was 13% complete in the single-level trial and was available for all of the 2-level trial.

RESULTS

Measurements of 259 adjacent levels found that 55.2% of disk spaces had a height of <4 mm. Among operated levels, 82.7% were <4 mm. When a 4 mm TDR was available, it was used in 38.4% of operated levels in the 1-level trial and 54.3% of levels in the 2-level trial.

CONCLUSIONS

Among nonoperated levels, 55.2% were of height <4 mm, suggesting that TDRs of greater heights may potentially overdistract the disk space. The 4 mm TDR was selected by surgeons in 49.4% of all implanted levels, suggesting a preference for smaller TDR height. Further investigation is warranted to determine if the lower height implants are related to clinical and/or radiographic outcomes.

LEVEL OF EVIDENCE

Level III.

Recurrent spinal stenoses after implant removal: A case report

Introduction and importance

Cervical spinal stenoses is becoming more and more common due to the aging population. The degenerative changes in the spine including discopathy or spondylosis will constrict and narrow the spinal canal and the usual site for the stenoses is in the cervical and lumbar region. The mainstay of the treatment is surgical, however there still a controversy regarding which approach is the best for the patient with cervical stenoses.

Case presentation

In this case reports we present a case of 63-year-old male who came to our center due to weakness of arms and legs due to cervical spinal stenoses and underwent treatment after which the implant was removed, and the symptoms worsens.

Clinical discussion

We performed Anterior Cervical Discectomy and Fusion (ACDF) and insertion of a cages to stabilize the spine. ACDF associated with lower intraoperative blood loss, similar surgical duration, and complication rate compared with laminoplasty. From the radiological outcome, ACDF showed a better-preserved cervical lordosis, which could affects patient's quality of life.

Conclusion

ACDF is one of the viable methods for the treatment of the cervical stenoses with lower complication rate and good clinical outcomes.

•

Cervical spinal stenoses is a common degenerative disease in aging population.

•

There still a controversy regarding the best surgical approach for the patient.

•

An option includes Anterior Cervical Discectomy and Fusion (ACDF).

•

ACDF with insertion of cages provides less complication rate.

•

ACDF with insertion of cages also result in better clinical outcomes.

Influence of Predominant Neck vs Arm Pain on ACDF Outcomes: A Follow-Up Study

OBJECTIVE

To assess differences in postoperative PROMs and MCID attainment following single-level ACDF based on predominant preoperative pain symptom.

METHODS

Primary, single-level ACDFs were identified. PROMs included VAS arm and neck/SF-12 PCS/PROMIS-PF/NDI, collected preoperatively and at 6-week/12-week/6-month/1-year/2-year postoperative timepoints. Patients were grouped: pAP (preoperative VAS arm > preoperative VAS neck) vs pNP (preoperative VAS neck > preoperative VAS arm). Chi-square and Student's t-test compared demographic and perioperative characteristics. Student's t-test evaluated change from preoperative to postoperative PROM values, and compared PROMs between groups. MCID achievement was determined using established threshold values. MCID attainment rates were compared using chi-squared.

RESULTS

110 patients were assessed-52 pNP/58 pAP. Demographics did not differ between cohorts. Total 1-year arthrodesis rate was 95.7% and did not differ by grouping. pNP patients improved significantly from preoperative to postoperative at 12-weeks-1-year for PROMIS-PF, 6-months/1-year for SF-12 PCS, 6-weeks-1-year for VAS neck, 6-weeks-6-months for VAS arm, and 6-weeks through 2-years for NDI(p≤0.035, all). pAP patients improved significantly from preoperative to all postoperative timepoints for PROMIS-PF, 6-months-2-years for SF-12 PCS, 6-weeks-1-year for VAS neck, 6-weeks-1-year for VAS arm, and 6-weeks-6-months for NDI(p≤0.040, all). Mean PROMIS-PF was higher for pAP at 6-weeks, preoperative VAS neck lower for pAP, and preoperative VAS arm higher for pAP(p≤0.013, all). MCID attainment was significantly higher among pAP only for PROMIS-PF from 6-weeks-6-months, SF-12 PCS 6-weeks, and VAS arm 12-weeks.

CONCLUSION

Predominant pain symptom demonstrated little effect on perioperative characteristics and postoperative PROMs. ACDF candidates will likely experience similar clinically meaningful postoperative improvements in physical function/disability/pain.

Radiological Changes in Adjacent and Index Levels after Cervical Disc Arthroplasty

PURPOSE

The purpose of this retrospective study was to evaluate radiological and clinical outcomes in patients undergoing cervical disc arthroplasty (CDA) for cervical degenerative disc disease. The results may assist in surgical decision-making and enable more effective and safer implementation of cervical arthroplasty.

MATERIALS AND METHODS

A total of 125 patients who were treated with CDA between 2006 and 2019 were assessed. Radiological measurements and clinical outcomes included the visual analogue scale (VAS), the Neck Disability Index (NDI), and the Japanese Orthopaedic Association (JOA) myelopathy score assessment preoperatively and at ≥2 years of follow-up.

RESULTS

The mean follow-up period was 38 months (range, 25-114 months). Radiographic data demonstrated mobility at both the index and adjacent levels, with no signs of hypermobility at an adjacent level. There was a non-significant loss of cervical global motion and range of motion (ROM) of the functional spinal unit at the operated level, as well as the upper and lower adjacent disc levels, compared to preoperative status. The cervical global and segmental angle significantly increased. Postoperative neck VAS, NDI, and JOA scores showed meaningful improvements after one- and two-level CDA. We experienced a 29.60% incidence of heterotrophic ossification and a 3.20% reoperation rate due to cervical instability, implant subsidence, or osteolysis.

CONCLUSION

CDA is an effective surgical technique for optimizing clinical outcomes and radiological results. In particular, the preservation of cervical ROM with an artificial prosthesis at adjacent and index levels and improvement in cervical global alignment could reduce revision rates due to adjacent segment degeneration.

Cervical Transdural Discectomy with Laminoplasty for the Treatment of Multi-segment Cervical Spinal Stenosis Accompanied with Cervical Disc Herniation: Technical Note and Clinical Outcome

Objective

To describe the surgical technique of cervical transdural discectomy with laminoplasty (CTDL) for the treatment of multi‐segment cervical spinal stenosis (CSS) accompanied with cervical disc herniation (CDH) and investigate its surgical outcomes and complications.

Methods

This was a clinical study. Between 2012 and 2018, 31 patients (13 males and 18 females) with multi‐segment CSS (over two cervical segments) accompanied with huge CDH and underwent CTDL were enrolled in this study. The details of CTDL technique with general anesthesia was described by the authors. The average follow‐up period of patients was 65.03 months (range from 24 to 126 months). Perioperative parameters such as age, sex, operative level, operative time, estimated blood loss, ambulation time, and operative complications were recorded. The results of clinical metrics such as the visual analog scale (VAS) and Japanese Orthopaedic Association (JOA) scores in the preoperative and during the follow‐up period were obtained and used to evaluate clinical outcomes. Radiographic improvement was evaluated by the compression ratio, sagittal maximum spinal cord compression (SMSCC), and cervical range of motion (ROM). The preoperative and postoperative follow‐up parameters (VAS, JOA, Compression ratio, SMSCC, and ROM) were assessed with paired t test. A P‐value <0.05 was considered statistically significant.

Results

In the study, the mean age of the 31 patients was 55.23 ± 10.97 years. The mean operative time was 192.45 ± 24.17 min (ranging from 150 to 245 min), and intraoperative blood loss was 322.58 ± 129.00 mL (ranging from 150 to 600 mL). The VAS neck pain was improved significantly over the follow‐up period (P < 0.05, respectively). The VAS arm pain improved significantly from 6.26 ± 0.93 preoperatively to 1.74 ± 0.63 at 24 months postoperatively (P < 0.001). There was no significant difference in improvement of VAS arm pain between 24 months postoperatively and final follow‐up (P = 0.180). Compared with preoperative JOA score, JOA score was significantly improved at 24 months postoperatively (14.79 ± 1.84 vs 9.66 ± 2.81, P < 0.001). Meanwhile, there were no statistically significant differences between the final follow‐up and the postoperative JOA scores (15.08 ± 1.71 vs 14.79 ± 1.84, P = 0.051). Postoperative patients showed significantly higher index of compression ratio (58.30 ± 8.51 vs 27.17 ± 3.89, P < 0.001) and lower SMSCC (25.12 ± 5.67 vs 33.66 ± 5.38, P < 0.001). In addition, there was no significant difference between preoperative and postoperative cervical ROM (P = 0.740). One patient observed postoperative symptom of C₆ nerve root injury, which was resolved within 24 months after the surgery; meanwhile, the neurological monitoring also reflected the intraoperative stretching of the C₆ nerve root. Two cases involved postoperative cerebrospinal fluid (CSF) leakage which may have been related to laceration of dura mater.

Conclusions

This study suggested that CTDL technique could acquire satisfactory surgical outcomes for patients with multi‐segment CSS accompanied with CDH, but the surgical indications of the patients need to be selected strictly.

The CT assessment of uncovertebral joints degeneration in a healthy population

Background

A retrospective study investigated the degeneration trend of uncovertebral joints in a healthy population based on CT assessment.

Methods

A total of 200 males and 160 females, aged 21–79 years old (50.82 ± 17.06), who underwent CT examination in our hospital from September 2020 to March 2021 were enrolled. Sixty patients were included in each age group. According to the Kellgren and Lawrence classification and CT was used to evaluate the uncovertebral joints degeneration in different groups.

Results

With the increase of age, the degeneration of each segment was gradually aggravated. The uncovertebral joints started degenerating in the 20 s, and the C5–6 is the most degenerative segment, followed by the C4–5 and C6–7. Significant degeneration occurred in each segment between the 40 s and 60 s and became more severe after the 70 s.

Conclusions

The modified Kellgren and Lawrence classification based on CT scan could provide a quantitative assessment of uncovertebral joints degeneration in a healthy population and could provide more details for artificial cervical arthroplasty.

Posterior intraprosthetic dislocation of cervical arthroplasty: illustrative case

BACKGROUND

Cervical disc herniation is a common condition usually treated with anterior cervical discectomy and fusion (ACDF) or, more recently, with cervical disc arthroplasty (CDA). Both treatments offer similar clinical results. However, CDA has been found to offer fewer medium- to long-term complications as well as potential reduction of long-term adjacent disc degeneration.

OBSERVATIONS

A 40-year-old man was treated with cervical discectomy and arthroplasty due to a C6-C7 disc herniation with left C7 radiculopathy. After the treatment, his postoperative follow-up appointments were uneventful for 9 months. However, after 9 months, he reported cervical pain and a right C7 radiculopathy after neck extension. Imaging confirmed a posterior intraprosthetic dislocation, the first case reported to date. The patient was received emergency surgery under neuromonitoring, and the prosthesis was replaced by an ACDF and anterior plate. The insert presented a rupture of the anterior horn. The patient presented no preoperative or postoperative neurological deficit, and his follow-up review revealed no issues.

LESSONS

Posterior intraprosthetic dislocation is an extremely rare complication. It may occur with Mobi-C cervical arthroplasty in the case of rupture and oxidation of the polyethylene insert. Spine surgeons should be aware of this potential major complication.