Cervical disc arthroplasty is safe across various obesity levels

Background context: As surgical indications for cervical disc arthroplasty (CDA) continue to expand, a growing patient population is now becoming indicated for this procedure. Little is known about whether CDA is safe in the overweight and obese populations, and how this procedure compares to anterior cervical discectomy and fusion (ACDF) in this particular demographic.

Purpose: To evaluate the outcomes of CDA across varying levels of body mass indices and to compare these to ACDF.

Design: Retrospective cohort study.

Patient sample: A total of 12,454 patients who underwent CDA and 45,513 patients who underwent ACDF between 2011 and 2020 were included in this study.

Outcome measures: The following data were observed for all cases: patient demographics, complications, revisions.

Methods: The PearlDiver database was queried to identify all adults who underwent single-level CDA. Patients were stratified by body mass index (BMI), defined as Healthy Weight (<25kg/m2), Overweight (25-30kg/m2), Obese (30-40kg/m2), and Morbidly Obese (>40kg/m2). Patient demographics and comorbidities were compared before matching, and medical and surgical complications were compared after matching for age, sex, and Charlson Comorbidity Index (CCI). Similar comparative analyses were performed on all obese patients (>30kgm/2) who underwent single-level CDA and single-level ACDF.

Results: In total, 1907 Healthy Weight, 3295 Overweight, 5431 Obese, and 1821 Morbidly Obese patients were included. The mean age was between 45.43 and 47.41 years, 57.12% and 71.68% were female, and mean CCI was 1.16-1.73 across groups (all p<.001). Mean CCI (Healthy Weight=1.16, Overweight=1.31, Obese=1.47, Morbidly Obese=1.63) and rate of comorbidities, such as diabetes (19.19%, 25.74%, 37.51%, 48.65%), hypertension (45.20%, 56.18%, 69.21%, 76.22%), and hyperlipidemia (49.34%, 60.61%, 65.33%, 64.96%), generally increased with increasing BMI (p<.001). After matching, mean age was 44.59 years, 70.98% were female, and mean CCI was 1.07 for all groups. At 90 days postoperatively, medical complications, including infection, wound dehiscence, and readmissions, were comparable (p>.05). At 2 years postoperatively, anterior revision was higher in Healthy Weight patients (30.27%, 28.11%, 24.71%, 24.96%, p=.005) but other surgical complications, including dysphagia, dysphonia, and implant failure, were otherwise comparable (p>.05). Comparison of all obese patients across cervical procedures revealed higher rates of 90-day emergency department visits (ACDF=21.56% vs 16.65%, p<.001) and 1-year hardware removal (1.49% vs 0.81%, p=.002), wound exploration (0.73% vs 0.35%, p=.018), and posterior fusion (1.14% vs 0.44%, p<.001) and lower rates of anterior revision (18.82% vs 23.68%, p<.001) in ACDF patients compared to CDA patients.

Conclusion: CDA may be safe across varying levels of obesity without any appreciable change in medical and surgical complications. In addition, single-level ACDF may result in higher complications than single-level CDA in the obese population.