To explore the differences and roles of fibular morphology in patients with knee osteoarthritis of different severity levels, as well as in knee osteoarthritis with various deformities.

A retrospective analysis was conducted on patients who visited the Dali Bai Autonomous Prefecture People’s Hospital from January 2021 to October 2023. Inclusion criteria: patients aged ≥18 years, with standard standing full-length radiographs of the lower extremities and diagnosis of knee osteoarthritis. Exclusion criteria: history of lower limb trauma or surgery, lower limb skeletal dysplasia or bone diseases. A total of 269 patients (447 knees) were finally included, comprising 75 males and 194 females, with age ranging from 18 to 86 years. The Kellgren-Lawrence (K-L) grading system was used to assess the radiological severity of knee osteoarthritis. Radiological measurement indicators included: hip-knee-ankle angle, total fibular curvature, proximal fibular curvature, distal fibular curvature, fibular-tibial distance, and tibiolfibular interosseous space area. Univariate analysis was first performed to evaluate the differences in fibular morphological indicators in the occurrence and progression of knee osteoarthritis, followed by logistic analysis to determine the role of each fibular morphological indicator in the occurrence and progression of knee osteoarthritis.

With the increase in K-L grading, no significant differences were observed in overall total fibular curvature, proximal fibular curvature, distal fibular curvature, fibular-tibial distance, and tibiolfibular interosseous space area among the groups (P>0.05). The proximal fibular curvature and distal fibular curvature in the varus knee osteoarthritis group were both greater than those in the valgus knee osteoarthritis group, with statistically significant differences (t=1.985, -3.642, both P<0.05), while overall total fibular curvature, fibular-tibial distance, and tibiolfibular interosseous space area showed no significant differences among the groups (all P>0.05). Binary logistic regression analysis indicated that differences in proximal fibular curvature [odds ratio (OR)=1.312, 95% confidence interval (CI) (1.071, 1.607) , P=0.009] and distal fibular curvature (OR=0.712, 95% CI (0.589, 0.861), P<0.001) were statistically significant.

This study found no statistically significant differences in fibular morphological imaging parameters between groups of different severity of knee osteoarthritis. However, differences were observed in the proximal and distal fibular curvatures between varus and valgus knee osteoarthritis. Proximal fibular curvature may be a risk factor for knee osteoarthritis in varus deformity, Distal fibular curvature may also be a protective factor for varus deformity knee osteoarthritis.