Robotic-Arm Assisted THA: Improved Acetabular Component Accuracy and Patient-Reported Outcome Measures.

Introduction: Acetabular component placement is critical for total hip arthroplasty (THA) stability and clinical outcomes. We investigated cup placement with robotic-arm assisted (RA) and conventional manual (CM) THA and compared patient-reported outcome measures (PROMs) and dislocations.

Materials and methods: Thirty-seven patients were randomized to undergo RA or CM primary THA. Computed tomography scans were completed preoperatively and at three months. Component version and inclination were analyzed with target anteversion of 20° and inclination of 40°. PROMs were collected to assess early clinical outcomes.

Results: Seventeen RA and 20 CM THAs were performed. Overall, 1/17 RA and 8/20 CM components fell outside the Lewinnek safe zone. No RA components fell outside the safe zone for inclination and one did for version. Three CM components were outside the inclination safe zone and six were outside for version. There were no dislocations in either group. Improvements in all Hip Disability and Osteoarthritis Outcome Score (HOOS) subtype scores reached substantial clinical benefit thresholds in both groups. One-year HOOS symptom and sports score improvements were significantly higher in the RA group. PROMIS-10 mental health improvement was significantly higher in the CM group at six months, but not at one year.

Conclusions: Robotic-arm assistance may result in more consistent placement within the Lewinnek safe zone. There were improvements in PROMs in both groups, but there were different effects on individual PROMS between groups. Further study is necessary to determine the clinical significance of these improvements.