Postoperative Femoro-tibial Rotational Change and High Rotational Offset Are Associated With Worse Clinical Outcomes in Total Knee Arthroplasty

BACKGROUND: Perioperative changes in femoro-tibial rotational alignment and the optimal postoperative femoro-tibial rotational alignment following total knee arthroplasty (TKA) are not well characterized. This study aimed to evaluate femoro-tibial rotational alignment following TKA and the effects on postoperative patient-reported outcome measures. METHODS: We analyzed 250 knees undergoing TKA for osteoarthritis. Axial femoro-tibial rotation was determined using the anatomical femoro-tibial rotational angle (FTRA) on pre and postoperative computed tomography. Low rotational offset alignment (LO) and high rotational offset alignment (HO) were defined as a postoperative FTRA of within ± 5° and over ± 5° relative to the preoperative, respectively. A greater than 5° change in intraoperative FTRA was defined as a rotational change (RC). The patient-reported outcome measures were evaluated using the pain, symptoms, and activities of daily living (ADL) subscales of the Knee injury and Osteoarthritis Outcome Score before and one year after surgery. All knees were classified into four groups [LO/RC(-), LO/RC(+), HO/RC(+), and HO/RC(-)] to investigate the relationship between LO/HO and RC. RESULTS: The proportion of knees with LO and HO were 45.6 and 54.4%, respectively. The HO was associated with significantly lower change in pain and change in ADL than was LO (P < 0.01, P = 0.03, respectively). The RC, which occurred in 40.4% of the knees (n = 101), was associated with significantly lower values in change in pain, change in symptom, and change in ADL than was its absence (P < 0.01, 0.02, and 0.01, respectively). The distribution of knees with LO/RC(-), LO/RC(+), HO/RC(+), and HO/RC(-) was 32.0, 13.6, 26.4, and 28.0%, respectively. Only HO/RC(+) knees showed significantly decreased change in pain and change in ADL compared to LO/RC(-) knees (P < 0.01 and = 0.03). CONCLUSIONS: Changes in femoro-tibial rotation and high femoro-tibial rotational offset alignment were associated with worse clinical outcomes following TKA. In particular, high femoro-tibial rotational offset alignment with femoro-tibial RC was associated with the worst clinical outcomes. LEVEL OF EVIDENCE: III (Retrospective Cohort Study).