Intraoperative gap assessment in robotic-assisted bicruciate retaining TKA for knee osteoarthritis

Primary robotic-assisted (RA) TKA is becoming increasingly common worldwide. However, there are currently no reports of RA TKA utilizing a bi-cruciate ligament-retaining (BCR) prosthetic design. The aim of this study was to perform intra-operative gap assessment with the goal of improving post-operative patient-reported outcome measures (PROMs) at a mean follow-up of 20.4 months in patients undergoing RA BCR TKA. The study included 33 knees with knee osteoarthritis who underwent BCR TKA using RA techniques. Intra-operative soft tissue balance was assessed by evaluating the medial joint gap (MJG), lateral joint gap (LJG). The femoro-tibial angle (FTA), tibial posterior slope, and the rotational angles of both the femoral components were measured using three-dimensional computed tomography. LJG at 0° of flexion and correction of tibial posterior slope showed a positive correlation with PROMs. In contrast, LJG at 90° of flexion, correction of FTA, and femoral component rotational angle were negatively correlated with PROMs. The area under the curve (AUC) for MJG at 0° was 0.706, with a cut-off value of 1.6 mm identified using the Youden index.