Rising adoption of imageless navigation in total hip arthroplasty for morbid obesity: do clinical outcomes improve? A matched cohort study.

PURPOSE: Total hip arthroplasty (THA) presents unique technical challenges in patients who have morbid obesity, and benefits of imageless navigation in this population remain unclear. This study compared complications, thromboembolic events, and emergency department utilization between imageless navigation-assisted and manual THA in patients who have morbid obesity.

METHODS

A retrospective cohort study was performed using the PearlDiver database. Patients who have morbid obesity (BMI ≥ 40) undergoing elective primary THA between 2010 and 2021 were identified. Cases performed with robotic assistance or image-based navigation were excluded. Patients were stratified by intraoperative technique into manual and imageless navigation cohorts and matched 1:3 on age, sex, year of procedure, and comorbidities. Surgical complications, thromboembolic events, revision procedures, and emergency department visits were evaluated at multiple postoperative time points and compared using univariable regression.

RESULTS

After matching, 4,499 patients who have morbid obesity were included, comprising 3,367 manual (74.8%) and 1,132 imageless navigation (25.2%) cases. No significant differences were observed between cohorts in rates of surgical complications, including infection, dislocation, periprosthetic fracture, mechanical loosening, chronic pain, or leg length discrepancy at any evaluated time point (P > 0.05). Thromboembolic events were uncommon and did not differ between groups at 30 or 90 days. Emergency department visits and revision rates were also similar at all time points.

CONCLUSIONS

Among patients who have morbid obesity undergoing primary THA, imageless navigation was not associated with improved outcomes compared with manual techniques, suggesting postoperative risk is driven primarily by obesity-related factors. Surgeons should weigh resource utilization and patient characteristics when selecting operative technique.