Abstract
Introduction
Robotic-assisted total knee replacement (RA-TKR) was the most performed primary TKR in Australia in 2023 (AOA, 2024). Operative duration is clinically important, as longer procedures correlate with increased risk of readmission, reoperation, surgical site infection, wound complications, and transfusion (George et al., 2018). Instumented mechanically aligned TKRs have previously been shown to have shorter operative times than technology-assisted procedures (Tompkins et al., 2022), However, the use of technology assistance allows for individualised alignment techniques including objective soft tissue balancing, such as functional alignment. Comparative data on operative timing between RA-TKR and navigated (N-TKR) in functionally aligned knees is limited. The Stryker Triathlon system, the most utilised knee implant in Australia, supports both MAKO robotic and OrthoMap Precision navigation platforms, allowing direct comparison.
Objectives:
To compare overall and step-specific operative times for MAKO RA-TKR versus OrthoMap Precision N-TKR using functional alignment for both groups.
Methods:
A single health service retrospective study was conducted on consecutive patients undergoing unconstrained primary TKR for osteoarthritis between June 2024 and July 2025, assisted by Stryker MAKO or Precision navigation. Exclusion criteria included non-osteoarthritis indications, prior knee trauma or surgery, constrained prostheses, and revision procedures. Local ethics approval was obtained. Baseline demographics, surgeon seniority, and operative time points (surgical commencement, pin placement, skin incision, registration, balancing, bone cuts, trialling, implantation, wound closure) were recorded. Independent t-tests were used to assess differences.
Results:
136 patients were studied (RA-TKR n=72; N-TKR n=64), with comparable age, sex, BMI, and ASA score. Mean total operative time was 11.2 minutes shorter for RA-TKR (74.2 ± 2.9 min [95% CI]) compared to N-TKR (85.5 ± 4.6 min; p < 0.00001). Excluding wound closure, RA-TKR was 8.3 minutes faster than N-TKR (54.2 ± 2.7 vs 62.5 ± 3.9] min; p < 0.0003). The greatest time difference was seen during bone cuts, with RA-TKR 6.3 minutes faster than N-TKR (10.0 ± 0.89 vs 16.3 ± 1.5 min; p < 0.00001). Subgroup analysis of consultant-led and uncemented tibio-femoral components showed similar significant reductions.
Conclusions:
In this single health service series using the Stryker Triathlon system, MAKO RA-TKR demonstrated significantly shorter operative times than OrthoMap Precision N-TKR, driven primarily by reduced bone cutting duration. These findings show a significant time efficiency advantage of robotic assistance over computer navigation in functionally aligned primary TKRs.