Association between abnormal native tibial torsion and poorer clinical outcomes following robotic-assisted total knee arthroplasty: follow-up of at least two years.

The study aimed to compare clinical outcomes of robotic-assisted total knee arthroplasty (RA-TKA) between patients with tibial rotational malalignment and those with normal tibial rotational alignment. From 2022 to 2023, the retrospective cohort included 382 patients who received RA-TKA using a functional alignment (FA) strategy for end-stage varus knee osteoarthritis (KOA). One surgeon performed all procedures. A tibial torsion angle (TTA) > 30° defined the abnormal tibial torsion (ATT) group, whereas a TTA ≤ 30° defined the normal tibial torsion (NTT) group. Following 1:1 matching, each group comprised 77 patients. Clinical outcomes were evaluated with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), Knee Society Score (KSS) function, and Forgotten Joint Score (FJS); anterior knee pain (AKP) and patellofemoral crepitus were also recorded. Postoperative data collection occurred after patients reached the minimum 2-year follow-up. Similar WOMAC, OKS, and KSS function scores were observed for the ATT and NTT groups at both the preoperative assessment and postoperative follow-up. Postoperative FJS was significantly lower for the ATT group relative to the NTT group (75.5 ± 23.5 vs. 83.4 ± 18.4, P = 0.045). The incidences in the ATT and NTT groups were 25% and 10%, respectively, for patellofemoral crepitus (P = 0.020) and 19% and 8%, respectively, for AKP (P = 0.035), with both outcomes occurring more frequently in the ATT group. Patient dissatisfaction was numerically higher in the ATT group (16%) than in the NTT group (6%), but the between-group difference was nonsignificant (P = 0.072). Clinical outcomes improved after RA-TKA in both the ATT and NTT groups. At a minimum 2-year follow-up, excessive native tibial torsion was associated with lower FJS and higher incidences of patellofemoral crepitus and AKP. Notably, the observed FJS difference did not reach the prespecified minimal clinically important difference (MCID), and its clinical significance requires further investigation.