Primary Robotic-Arm Assisted Total Hip Arthroplasty: An Analysis of 501 Hips With 44-Month Follow-up

The aim of this study was to report patient-reported outcome measurements in a large group of patients who underwent robotic-arm assisted primary total hip arthroplasty (THA). Prospectively collected data were retrospectively reviewed between April 2012 and May 2017. Primary THAs using the Mako robotic-arm assisted (Mako Surgical Corp [Stryker]) with minimum 2-year follow-up for Harris Hip Score (HHS) and Forgotten Joint Score-12 (FJS-12) were included. Exclusion criteria were body mass index (BMI) of 40 kg/m(2) or greater, age younger than 21 years, workers' compensation, or unwillingness to participate. Visual analog scale (VAS) score for pain and patient satisfaction score were obtained. Intraoperative measurements for leg length, global offset, acetabular inclination, and version were documented. A total of 501 hips were included, with 57.29% of the patients being female. Mean follow-up was 43.99 +/- 15.59 months. Mean age was 58.70 +/- 9.41 years. Mean BMI was 28.41 +/- 4.55 kg/m(2). Mean HHS was 90.87 +/- 13.45, mean FJS-12 was 79.97 +/- 25.87, mean VAS score was 1.20 +/- 2.06, and mean patient satisfaction score was 8.85 +/- 2.08. Intraoperative values for acetabular inclination and version were 40.0 degrees +/- 2.2 degrees and 20.5 degrees +/- 2.4 degrees, respectively. The rate of revision due to instability was 0.2%. Patients who received primary robotic-arm assisted THA reported excellent results at 44-month follow-up for multiple patient-reported outcome measurements. Consistency in acetabular cup placement accuracy was achieved regarding the Lewinnek and Callanan safe zones.