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Published on: February 27, 2018
Robotic-assisted total knee arthroplasty achieves better alignment goals compared to the conventional technique
Narayan Hulse1, Jesmick Ponniah1, Rahul Desai1
1Department of Bone and Joint Surgery, Fortis Hospital, Bangalore, India.
Background:
Robotic arm-assisted total knee arthroplasty (TKA) aims to improve potential inaccuracies in implant positioning and alignment. Newer alignment targets involve complex calculations and minute adjustments in component positioning that are difficult with conventional techniques.
Methods:
A consecutive series of 400 primary TKAs performed in a single institution between August 1, 2024, and December 31, 2024, were studied retrospectively. Coronal plane alignment was assessed using long-leg standing anteroposterior radiographs taken preoperatively and eight weeks postoperatively. In the robotic group, functional alignment principles were used, and target alignment data were obtained from the robotic system. Postoperative alignment exceeding ±3° from the intraoperative alignment was defined as an outlier. In the conventional group, alignment exceeding ±3° from the neutral mechanical axis was considered an outlier.
Results:
During the study, 200 TKAs were performed using the Mako robotic system (Stryker, Fort Lauderdale, Florida, USA) following functional alignment principles, and 200 using conventional mechanical alignment. The mean coronal alignment recorded in the robotic system was 178.39° (SD = 1.71). The postoperative mean alignment in the robotic group was 178.07° (SD = 1.85), and in the conventional group, 177.04° (SD = 2.87). Nineteen patients (9.5%) were outliers in the robotic group (mean 179.3°, SD = 4.9), compared to 83 (41.5%) in the conventional group (mean 174.9°, SD = 3.1), showing statistical significance. Robotic TKA also preserved posterior condylar offset (3.53 ± 0.37 vs 3.36 ± 0.40; p < 0.001), achieved lower tibial slope (2.37° ± 1.16 vs 4.36° ± 2.18; p < 0.001), and slightly lower femoral flexion (3.42° ± 2.27 vs 4.24° ± 3.81; p = 0.009).
Conclusions:
Robotic TKA shows significantly fewer alignment outliers than conventional techniques. It achieves better target alignment using functional alignment principles. Although not free of outliers, robotic TKA offers greater accuracy for newer alignment goals, warranting long-term evaluation.
