Abstract

Background: Traditionally mechanical alignment has been the gold standard for total knee replacement (TKR). Patients with moderate to severe varus deformity undergoing TKR, often require soft tissue release. The use of robotic assisted (RA)-TKR and functional alignment, should allow the surgeon to make less soft tissue releases to restore patients to constitutional varus. The purpose of this study is to assess clinical outcomes for patients undergoing RA-TKR, who had ≥15 degrees of varus deformity while manipulated under anaesthesia. Methods: Data from all patients, with osteoarthritis, who underwent a RA-TKR under a single surgeon between December 2016 and January 2022 was collected. Data were collected pre-operatively and at 1 year follow up, for patient reported outcome measures including the Forgotten Joint Score (FJS) and Oxford Knee Score (OKS). Results: There were 92 patients with ≥15 degrees varus who received RA-TKR. Of these, 51 had a body mass index (BMI) ≥30 kg/m2 and 41 had a BMI <30 kg/m2. There were 13 (14.1%) patients who required soft tissue release. The average varus measured intra-operatively pre-implantation was 16.4°±1.8° and post implantation was 7.9°±2.8°. Fifty-nine patients were assessed at 1 year follow up, the average FJS was 78.6±20.4 and the average OKS at 1 year follow up was 44.3±4.3. Conclusions: Following primary RA-TKR, patients with varus deformity ≥15 degrees, had good patient reported outcomes with low numbers of soft tissue release. Patients with a BMI ≥30 kg/m2 also had satisfactory patient reported outcomes.