Robotic-assisted total knee arthroplasty improves the rotational mismatch between femoral and tibial components, but not the forgotten joint score 12: a single-center retrospective cohort study.

PURPOSE: The primary aim of this study was to compare postoperative short-term patient reported outcome measurements (PROMs) and rotational mismatch between femoral and tibial following conventional jig-based total knee arthroplasty (Conv-TKA) versus robotic-assisted TKA (RA-TKA) using three-dimensional computed tomography (3DCT) measurements. METHODS: This retrospective, consecutive case-control trial included 83 patients with varus osteoarthritis of the knee undergoing Conv-TKA versus RA-TKA using bi-cruciate stabilized TKA. The rotational mismatch of the femoral and tibial components between the two groups were compared using 3DCT measurements. PROMs (2011 Knee Society Score (KSS), forgotten joint score-12 (FJS-12), patella score were compared in patients between 1 and 2 years postoperatively. RESULTS: The two groups did not exhibit significant differences in any of the following preoperative factors: age at surgery, body mass index (BMI), preoperative range of motion (ROM), hip-knee-ankle (HKA) angle. There were no significant differences in postoperative HKA angle and tibial rotation angle, the absolute values of the femoral rotational angle and rotational mismatch were significantly smaller in the RA-TKA group than in the Conv-TKA group (both p < 0.01). Neither Postoperative PROMs (2011 KSS: pain, patient satisfaction, patient expectation, advanced activities score) nor patella score differed significantly between the groups, but FJS-12 was significantly better in the Conv-TKA group than in the RA-TKA group (p < 0.01). CONCLUSIONS: RA-TKA did not improve FJS-12 compared to Conv-TKA, but did result in more accurate rotational alignment of femoral component and rotational mismatch between the femoral and tibial components. LEVEL OF EVIDENCE: IV.