Robot-assisted total knee arthroplasty using modified sub-vastus approach: A series of 120 knees

The application of the Sub-vastus (SV) approach in Robot-assisted total knee arthroplasty (RATKA) is a relatively new practice with many potential benefits. This study aimed to assess the cases that underwent robot-assisted knee replacement through the sub-vastus approach, using functional and clinical parameters.

This monocentric, single-surgeon, retrospective observational study included 81 consecutive cases (120 knees) who had undergone Robot-assisted total knee arthroplasty with the Sub-vastus approach. Their Postoperative evaluation included hemoglobin levels, functional outcomes like the straight leg raising test (SLRT), walking ability, and the Oxford Knee Score (OKS).

The average age of participants was 63.3 years. The mean hospital stay was 3.4 days (median 3 days). Perioperative drop in Hemoglobin concentration averaged 1.27 g/dl for unilateral and 1.5 g/dl for bilateral cases. By the second postoperative day, 85 % of the study group were able to perform active straight leg raising and 66 % were able to walk with support. These numbers increased to 95 % by the third day. The mean OKS was 45.832 (SD: 1.29).

The SV approach, when combined with RATKA, can yield improved functional results by showing the short-term benefits of a quadriceps-sparing technique, like less blood loss, faster recovery, and shorter hospital stay, while also enhancing surgical precision and accuracy in implant placement, thereby improving longevity. This combination is also effective in addressing severe deformities and obese cases, which previously were a limitation of the SV approach. Incorporating an oblique under-vastus release of the suprapatellar pouch and capsule was found to facilitate surgical access and may enhance procedural efficiency.