Characteristics of knee rotational alignment and related factors in patients with knee osteoarthritis: A case -...

Lower limb biomechanical abnormality plays a crucial role in the pathogenesis of knee osteoarthritis (KOA). Previous studies have primarily focused on the coronal plane biomechanics of the knee joint, with insufficient investigation into rotational abnormalities. This study investigated the characteristics of knee joint rotational alignment in KOA patients and analyzed its related factors. Computed tomography (CT) images were collected from 249 KOA patients admitted between December 2023 and November 2024, along with demographic data including age, gender, body mass index (BMI), and disease duration. Additionally, knee CT scans were obtained from 117 healthy elderly individuals, and 45 young adult volunteers were recruited for knee CT imaging. Comparative analysis of knee rotation angles was conducted among the 3 groups (KOA patients, healthy elderly controls, and young adult volunteers) to investigate the distribution characteristics of rotational alignment. Correlation analyses were performed between knee rotation angles and clinical parameters (age, sex, BMI, and disease duration) in the KOA patient group. Comparative analysis of knee rotation angles revealed that KOA patients exhibited significantly smaller rotation angles (2.52 [-2.79, 6.81]) compared to both healthy elderly controls (4.65 [3.42, 7.87]; P < .01) and young volunteers (5.23 [4.14, 6.96]; P < .01). Knee rotation angles showed significant positive correlations with disease duration (r = 0.633; P < .001) and BMI (r = 0.822; P < .001). No significant association was found between sex, age and knee rotation angles (P  > .05). Compared with healthy elderly controls and young volunteers, KOA patients demonstrated a bimodal distribution of knee rotation angles, with 1 subgroup exhibiting internal rotation and another showing excessive external rotation. Furthermore, knee rotation angles in KOA patients were significantly associated with disease duration and BMI, but not with sex and age.