Risk factors for varus knee osteoarthritis and their relationship with disease severity based on Kellgren-Lawrence classification.

Objective: To explore the hazard element of varus knee osteoarthritis (OA) and its relationship with Ailment severity based on the Kellgren-Lawrence classification.

Methods: This study selected a cohort of patients who initially presented without clinical signs of arthritis and did not exhibit knee valgus or varus deformities when assessed from a hip-knee-ankle alignment perspective, focusing on the internal side. As the study progressed some individuals developed OA. Eligible participants were those who had undergone a standard whole lower extremity weight-bearing X-ray examination at our orthopedic outpatient clinic. The study period spanned from January 2021 to April 2022, and the selection criteria were strictly applied throughout this timeframe. Data on clinical and X-ray indices, including fibular head height, Kellgren-Lawrence grade, joint line convergence angle (JLCA), proximal medial tibial angle (MPTA), and Hip-knee-ankle angle, were collected from patients.

Results: The study included 23 grade 0, 22 grade I, 32 grade II, 32 grade III, and 97 grade IV Kellgren-Lawrence classified patients. Significant differences in age, gender, and BMI were observed across groups (all P<0.05). With increasing OA severity, fibular head height and MPTA decreased, while JLCA and Hip-knee-ankle angle increased significantly (all P<0.05). Patients with OA exhibited larger fibular head height and MPTA but smaller JLCA and Hip-knee-ankle angle than those without arthritis (all P<0.05). Logistic regression analysis confirmed age, fibular head height, MPTA, JLCA, and Hip-knee-ankle angle as independent risk factors for varus knee OA (all P<0.05). Additionally, there was a strong positive correlation between age and fibular head height with disease severity, but a strong negative correlation between Hip-knee-ankle angle and disease severity (all P<0.05).

Conclusion: Patients with varus knee OA have larger fibular head height and MPTA than those without arthritis. Age, fibular head height, and Hip-knee-ankle angle are risk factors for the development of varus knee OA. The severity of arthritis and varus deformity increases with age and fibular head height.