Superiority of 2-Level Total Disk Replacement Using a Cervical Disk Prosthesis Versus Anterior Cervical Diskectomy and Fusion

The Statistical Fragility of Trials Comparing Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion: A Meta Analysis

STUDY DESIGN

Meta-analysis.

OBJECTIVE

To assess the robustness of randomized controlled trials (RCTs) that compared cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic degenerative cervical pathology by using fragility indices.

SUMMARY OF BACKGROUND DATA

RCTs comparing these surgical approaches have shown that CDA may be equivalent or even superior to ACDF due to better preservation of normal spinal kinematics.

MATERIALS AND METHODS

RCTs reporting clinical outcomes after CDA versus ACDF for degenerative cervical disc disease were evaluated. Data for outcome measures were classified as continuous or dichotomous. Continuous outcomes included: Neck Disability Index, overall pain, neck pain, radicular arm pain, and modified Japanese Orthopedic Association scores. Dichotomous outcomes included: any adjacent segment disease (ASD), superior-level ASD, and inferior-level ASD. The fragility index (FI) and continuous FI (CFI) were determined for dichotomous and continuous outcomes, respectively. The corresponding fragility quotient (FQ) and continuous FQ were calculated by dividing FI/CFI by sample size.

RESULTS

Twenty-five studies (78 outcome events) were included. Thirteen dichotomous events had a median FI of 7 [interquartile range (IQR): 3-10], and the median FQ was 0.043 (IQR: 0.035-0.066). Sixty-five continuous events had a median CFI of 14 (IQR: 9-22) and a median continuous FQ of 0.145 (IQR: 0.074-0.188). This indicates that, on average, altering the outcome of 4.3 patients out of 100 for the dichotomous outcomes and 14.5 out of 100 for continuous outcomes would reverse trial significance. Of the 13 dichotomous events that included a loss to follow-up data, 8 (61.5%) represented ≥7 patients lost. Of the 65 continuous events reporting the loss to follow-up data, 22 (33.8%) represented ≥14 patients lost.

CONCLUSION

RCTs comparing ACDF and CDA have fair to moderate statistical robustness and do not suffer from statistical fragility.

Effect of Fusion and Arthroplasty for Cervical Degenerative Disc Disease in Active Duty Service Members Performed at an Overseas Military Treatment Facility: A 2-Year Retrospective Analysis

INTRODUCTION

Among U.S. military active duty service members, cervicalgia, cervical radiculopathy, and myelopathy are common causes of disability, effecting job performance and readiness, often leading to medical separation from the military. Among surgical therapies, anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are options in select cases; however, elective surgeries performed while serving overseas (OCONUS) have not been studied.

MATERIALS AND METHODS

A retrospective analysis of a prospectively collected surgical database from an OCONUS military treatment facility over a 2-year period (2019-2021) was queried. Patient and procedural data were collected to include ACDF or CDA surgery, military rank, age, tobacco use, pre- and post-operative visual analogue scales for pain, and presence of radiographic fusion after surgery for ACDF patients or heterotopic ossification for CDA patients. Chi-square and Student t-test analyses were performed to identify variables associated with return to full duty.

RESULTS

A total of 47 patients (25 ACDF and 22 CDA) underwent surgery with an average follow-up of 192.1 days (range 7-819 days). Forty-one (87.2%) patients were able to return to duty without restrictions; 10.6% of patients remained on partial or limited duty at latest follow-up and one patient was medically separated from the surgical cohort. There was one complication and one patient required tour curtailment from overseas duty for ongoing symptoms.

CONCLUSIONS

Both ACDF and CDA are effective and safe surgical procedures for active duty patients with cervicalgia, cervical radiculopathy, and cervical myelopathy. They can be performed OCONUS with minimal interruption to the patient, their family, and the military unit, while helping to maintain surgical readiness for the surgeon and the military treatment facility.

Safety and Validity of Anterior Cervical Disc Replacement for Single-level Cervical Disc Disease: Initial Two-year Follow-up of the Prospective Observational Post-marketing Surveillance Study for Japanese Patients

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

Metal-on-metal versus metal-on-plastic artificial discs in two-level anterior cervical disc replacement: a meta-analysis with follow-up of 5 years or more

BACKGROUND CONTEXT

Although highlighted in joint arthroplasty studies, long-term outcomes between differing biomaterial composites, such as metal-on-metal (MoM) and metal-on-plastic (MoP) in anterior cervical disc replacement (ACDR) have not been thoroughly investigated.

PURPOSE

The purpose of this study was to evaluate the patient-reported clinical outcomes, overall reoperation rates, complications, and rates of ASD of MoM versus MoP artificial discs in two-level ACDR for the treatment of cervical DDD.

STUDY DESIGN/SETTING

Meta-analysis and systematic review.

PATIENT SAMPLE

Nine hundred eighty patients (442 MoM, 538 MoP) across seven studies.

OUTCOME MEASURES

Patient reported clinical outcomes (NDI, VAS-n, VAS-a), overall reoperation rates, complications, and rates of ASD.

METHODS

A systematic search strategy of three electronic databases (PubMed, CINAHL Plus, and SCOPUS) was conducted utilizing terms related to two-level ACDR. All studies included had a sample size of >10 patients, had a minimum 5-year follow-up, and reported data on adjacent segment disease. Cadaver studies, non-English manuscripts, articles with less than 5-year follow-up and studies in which only single-level ACDR was investigated were excluded. A total of seven studies were included in this analysis. Studies were analyzed for demographic data, clinical outcome scores (NDI, VAS-neck, and VAS-arm), overall reoperation rates, complications, and rates of ASD. A random-effects model of meta-analysis was used for groups that were determined to be heterogenous and a fixed-effects model was utilized for groups that were not. An overlap of 95% confidence intervals suggests no statistically significant difference at the p<.05 level.

RESULTS

Seven studies were included with data on 980 patients (442 MoM, 538 MoP). The study population was 52.84% female, with a mean age of 48.01 years, and a mean follow-up of 85.66 months. The mean improvement in NDI was 34.42 (95% CI, 32.49-36.36) and 29.72 (95% CI, 27.15-32.29) for the MoM and MoP groups, respectively. The mean improvement in VAS-neck was 11.20 (95% CI, 10.69-11.70) and 8.78 (95% CI, 7.81-9.74) for the MoM and MoP groups, respectively. The mean improvement in VAS-arm was 10.73 (95% CI, 9.83-11.63) and 8.49 (95% CI, 7.59-9.39) for the MoM and MoP groups, respectively. 3.85% (95% CI, 2.40-6.10) of patients who underwent ACDR with a MoM implant required reoperation compared to 5.33% (95% CI, 3.68-7.65) of patients with a MoP implant. Heterotopic ossification and dysphagia were the most common complications in both groups. The MoM cohort showed a higher incidence of HO (72.62% vs. 21.07%), but a lower incidence of dysphagia (0.96% vs. 16.31%) compared to the MoP cohort. The MoM cohort had a larger proportion of patients with ASD who underwent subsequent surgery at an adjacent level (7.89% MoM versus 1.91% MoP).

CONCLUSIONS

Our present meta-analysis suggests that the use of MoM artificial discs in two-level ACDR results in superior clinical outcome score improvement, but higher rates of ASD requiring secondary surgery compared to MoP discs after a follow-up period of 5 years or more.

Occurrence and clinical implications of heterotopic ossification after cervical disc arthroplasty with the Prestige LP Cervical Disc at 2 contiguous levels

OBJECTIVE

The authors sought to assess the impact of heterotopic ossification (HO) on clinical outcomes and angular range of motion (ROM) after cervical disc arthroplasty (CDA) performed with the Prestige LP Cervical Disc (Prestige LP disc) at 2 levels.

METHODS

HO was assessed and graded from 0 to IV for increasing severity on lateral neutral radiographs at each visit in 209 patients who underwent implantation of Prestige LP discs at 2 cervical levels in a clinical trial with extended 10-year follow-up. ROM was compared by using HO grade, and clinical outcomes were compared between HO subgroups (grade 0-II vs III/IV) based on HO severity at 2 and 10 years after surgery.

RESULTS

The grade III/IV HO incidence at either or both index levels was 24.2% (48/198) at 2 years and 39.0% (57/146) at 10 years. No statistical difference was found in overall success; neurological success; or Neck Disability Index (NDI), neck pain, arm pain, or SF-36 Physical Component Summary (PCS) scores between the HO subgroups (grade 0-II vs III/IV) at either 2 or 10 years. The cumulative rate of possible implant-related adverse events (AEs) was higher in patients having grade III/IV HO at 2 years (56.3%) and 10 years (47.8%) compared with those having grade 0-II HO at 2 years (24.4%) and 10 years (17.9%), specifically in 2 subcategories: spinal events and HOs reported by the investigators. No statistical difference was found between the HO subgroups in possible implant-related serious AEs or secondary surgeries at the index or adjacent levels. The average angular ROMs at index levels were lower in subjects with higher-grade HO at 2 and 10 years. The average ROMs at the superior level were 8.8°, 6.6°, 3.2°, and 0.3°, respectively, for the HO grade 0/I, II, III, and IV groups at 10 years, and 7.9°, 6.2°, 3.7°, and 0.6°, respectively, at the inferior level.

CONCLUSIONS

Radiographically severe (grade III or IV) HO after CDA with the Prestige LP disc at 2 levels did not significantly affect efficacy or safety outcomes (severe AEs or secondary surgeries). However, severe HO, particularly grade IV HO, significantly limited ROM, as expected.

Comparison of 2-year follow-up results of the hybrid surgery using Mobi-C combined with ROI-C and anterior cervical discectomy and fusion for the treatment of contiguous two-level cervical degenerative disc diseases

Although the Mobi-C artificial disc and the ROI-C cervical cage have been widely used in the treatment of cervical degenerative disc diseases (CDDD), few reports addressed the features of combined application of both devices. This study is aimed at comparing the clinical and radiological outcomes of treating contiguous two-level CDDD using Mobi-C and ROI-C combined in a hybrid surgery (HS) with anterior cervical discectomy and fusion (ACDF) using ROI-C. We reviewed ninety-one patients who underwent HS (n = 48) or ACDF (n = 43) surgery for symptomatic contiguous two-level CDDD. >2 years' clinical and radiological outcomes were reviewed and evaluated retrospectively. At the last follow-up, significant improvement in the mean VAS, JOA, and NDI scores was found both in the HS and ACDF groups (p < 0.05), while the differences between groups were not significant (p > 0.05). The global range of motion (ROM) in the HS group was significantly larger than that in the ACDF group (p < 0.05). The local lordosis improved significantly after surgery in all patients (p < 0.05). Bone resorption and heterotopic ossification (HO) were found after surgery. The result showed that, for the selected patients, HS may provide an alternative approach for the treatment of contiguous two-level CDDD. HS also offers the benefit of both greater global ROM and greater ROM at the Mobi-C index level. Some degree of bone resorption may be an integral component in the early stage of bony fusion in the cage index level. Further studies and long-term follow-up are still needed.

Comparative analysis of anterior cervical discectomy and fusion in the inpatient versus outpatient surgical setting

OBJECTIVE

In a large, consecutive series of patients treated with anterior cervical discectomy and fusion (ACDF) performed by a single surgeon, the authors compared the clinical and surgical outcomes of patients who underwent ACDF in an inpatient versus outpatient setting.

METHODS

Patients undergoing primary ACDF were retrospectively reviewed and stratified by surgical setting: hospital or ambulatory surgical center (ASC). Data regarding perioperative characteristics, including hospital length of stay and complications, were collected. Neck Disability Index (NDI) and visual analog scale (VAS) scores were used to analyze neck and arm pain in the preoperative period and at 6 weeks, 3 months, 6 months, and 12 months postoperatively. Postoperative outcomes were compared using chi-square analysis and linear regression.

RESULTS

The study included 272 consecutive patients undergoing a primary ACDF, of whom 172 patients underwent surgery at a hospital and 100 patients underwent surgery at an ASC. Patients undergoing ACDF in the hospital setting were older, more likely to be diabetic, and had a higher comorbidity burden. Patients receiving treatment in the ASC were more likely to carry Workers' Compensation insurance. Patients in the hospital cohort were more likely to have multilevel procedures, had greater blood loss, and experienced a longer length of stay. In the hospital cohort, 48.3% of patients were discharged within 24 hours, while 43.0% were discharged between 24 and 48 hours after admission. Both cohorts had similar VAS pain scores on postoperative day (POD) 0; however, the hospital cohort consumed more narcotics on POD 0. One patient in the ASC cohort had a pretracheal hematoma that was evacuated immediately in the same surgical center. There were 8 cases of dysphagia in the hospital cohort and 3 cases in the ASC cohort, all of which resolved before the 6-month follow-up. Both cohorts demonstrated similar NDI and VAS neck and arm pain scores preoperatively and at every postoperative time point.

CONCLUSIONS

Although patients undergoing ACDF in the hospital setting were older, had a greater comorbidity burden, and underwent surgery on more levels than patients undergoing ACDF at an outpatient center, this study demonstrated comparable surgical and clinical outcomes for both patient groups. Based on the results of this single surgeon's experience, 1- to 2-level ACDFs may be performed successfully in the outpatient setting in appropriately selected patient populations.