Improved Functional Outcomes with Robotic Compared with Manual Total Hip Arthroplasty.

INTRODUCTION Functional outcome following total hip arthroplasty (THA) is affected by accurate component positioning and restoration of hip biomechanics. Robotic-assisted THA (rTHA) has been shown to improve accuracy of component positioning, but its impact on functional outcomes has not been demonstrated. The purpose of this study was to compare: 1) operative time; 2) estimated blood loss; 3) postoperative complications; and 4) patient-reported outcome measures (PROMs) between patients who either underwent rTHA or manual THA (mTHA). MATERIALS AND METHODS In this retrospective cohort study, a single-center database was used to identify all patients who underwent primary THA since introduction of rTHA at a large academic medical center. Surgical factors including operative time and estimated blood loss as well as postoperative complications were recorded. Validated PROMs following rTHA (n = 100) were compared with consecutive mTHA cases (n = 100) performed by the same fellowship-trained surgeon at a minimum one-year follow-up (24 ± 6 months). PROMs included the Short-Form 12 Health Survey (SF-12), UCLA activity score (UCLA), Western Ontario and McMaster (WOMAC) Osteoarthritis Index, and modified Harris Hip Score (mHHS). A categorical analysis was performed to determine differences in proportions of patients with mHHS scores of 90 to 100, 80 to 89, 70 to 79, and < 70 points between the two groups. Chi-square and two-tailed t-tests were used to compare categorical and continuous data between cohorts. RESULTS Mean operative time was nine minutes longer for the rTHA group compared with the mTHA group (131 ± 23 min vs. 122 ± 29 min, respectively, p = 0.012). Estimated intraoperative blood loss was significantly reduced for the rTHA group when compared to the mTHA group (374 ± 133 mL vs. 423 ± 186 mL, p = 0.035), and there was no difference in overall complication rates between the two groups (p = 0.101). Robotic-assisted THA demonstrated significantly higher mean postoperative mHHS (92.1 ± 10.5 vs. 86.1 ± 16.2, p = 0.002) and mean UCLA scores (6.3 ± 1.8 vs. 5.8 ± 1.7, p = 0.033) compared with mTHA. The difference between pre- and postoperative mHHS scores was statistically significant when comparing rTHA with mTHA (43.0 ± 18.8 vs. 37.4 ± 18.3, p = 0.035). There were no significant differences in SF-12 or WOMAC scores. There was a significantly higher proportion of patients with mHHS scores between 90 to 100 points (75% vs. 61%, p = 0.034) and a lower percentage with scores < 70 points (6% vs. 19%, p = 0.005) in the rTHA cohort compared with the mTHA cohort. DISCUSSION The rTHA cohort demonstrated significantly higher mean postoperative UCLA scores, higher mean postoperative mHHS scores, and a greater percentage of patients with mHHS of 90 to 100 points compared with mTHA at a minimum one-year follow-up. To our knowledge, this is the first study to demonstrate that robotic-assisted THA leads to improved patient-reported outcomes. The observed improvement in functional outcomes following rTHA is encouraging and warrants additional multi-center studies to determine if these advantages are maintained at longer follow-up intervals.