MAKO Robotic-Arm-Assisted Versus Conventional Dual-Incision Total Hip Arthroplasty: A Propensity-Score-Matched Retrospective Study

TL;DR

This study compares robotic-assisted and conventional hip replacement surgeries, finding that robotic assistance improves implant placement accuracy but not early patient recovery.

Contribution

The study demonstrates that robotic-arm assistance in hip surgery improves radiographic precision and biomechanical restoration without enhancing short-term functional outcomes.

Findings

Robotic assistance resulted in smaller deviations from planned acetabular orientation and higher proportion of cups within the Lewinnek safe zone.

Functional outcomes like HHS and OHS were comparable between robotic and conventional groups at six months.

Greater radiographic precision was independently linked to better patient-reported outcomes.

Abstract

Background: This propensity-score-matched retrospective study compared radiographic accuracy and short-term functional outcomes between MAKO robotic-arm-assisted and conventional dual-incision minimally invasive total hip arthroplasty (THA). It was hypothesized that robotic assistance would provide superior radiographic accuracy, primarily smaller absolute deviations from the planned acetabular inclination and anteversion and a higher proportion of cups within the Lewinnek safe zone, without improving early functional outcomes. Methods: Consecutive patients who underwent dual-incision total hip arthroplasty were retrospectively analyzed at two affiliated institutions between March 2023 and March 2025. The study included 52 robotic-arm-assisted cases. The dual-incision technique used an anterolateral incision for acetabular preparation and cup implantation and a posterolateral incision for femoral preparation and stem implantation. Propensity score matching (1:1) generated 52 balanced pairs for age, sex, body mass index (BMI), preoperative Harris Hip Score (HHS), ASA class, and diagnosis. Operative time, blood loss, radiographic accuracy (acetabular anteversion, inclination, leg-length discrepancy [LLD], femoral and combined offsets, and stem subsidence), and functional outcomes (HHS, Oxford Hip Score [OHS], Forgotten Joint Score-12 [FJS-12]) were compared. Results: The robotic group achieved smaller deviations from the planned anteversion (1.15° vs. 3.0°, p < 0.001) and inclination (1.33° vs. 4.5°, p < 0.001), with a higher proportion of cups within the Lewinnek safe zone (98.1% vs. 82.7%, p = 0.016). Significant improvements were also seen in femoral stem subsidence (p = 0.006) and offset restoration, although the reduction in leg-length discrepancy did not reach statistical significance. Operative time was longer (77.8 vs. 65.0 min, p = 0.001), while blood loss and 6-month functional scores were comparable (HHS, p = 0.144; OHS, p = 0.328). Multivariable regression confirmed that greater deviations in acetabular orientation, higher LLD, and increased subsidence were independent predictors of poorer functional outcomes. Conclusions: MAKO robotic-arm assistance was associated with improved radiographic accuracy and biomechanical restoration in dual-incision THA, but no direct short-term functional advantage was observed. Greater radiographic precision was independently associated with better patient-reported outcomes, suggesting that technical precision is a key factor in optimizing early postoperative outcomes, highlighting the importance of technical accuracy in total hip arthroplasty.

Figures