Background
The lateral anatomical and morphological characteristics of knees with varus knee osteoarthritis (OA) have not received sufficient attention. This study used several radiological parameters to describe the morphological characteristics of the lateral knee with OA to determine whether there are relationships between varus knee OA and parameters such as lateral plateau widening (LPW), proximal fibula curvature (PFC), and fibula height (FH).
Methods
The study retrospectively analyzed 1072 subjects [376 males, 696 females; mean age 66.84 ± 7.04 (range 46–83) years; mean body mass index (BMI) 26.98 ± 3.22 kg/m²] who underwent standard radiography for diagnosing or evaluating symptomatic knee joint disease. The 163 Kellgren and Lawrence (K-L) grades 0 and I knees were categorized into the no-knee-OA group, and the 909 K-L grades II–IV knees were classified into the knee-OA group. The medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and hip-knee-ankle angle (HKAA) were measured to investigate varus knee deformity. The LPW, PFC, and FH were measured. T-tests and chi-square tests were used to compare each index between the two groups. Binary logistic regression was performed to examine the correlation between indexes and knee OA occurrence. Principal component analysis was used to calculate the comprehensive principal component score of varus deformity, which was used to comprehensively evaluate the knee varus deformity degree by reducing the original data's dimension. Multiple logistic and linear regression analyses were performed to examine the correlations between the three parameters and K-L grades and the comprehensive principal component score of varus deformit.
Results
LPW and PFC were significantly greater and FH was significantly smaller in the knee-OA group than in the no-knee-OA group. LPW, PFC, and FH were correlated with knee OA occurrence. One principal component, named the comprehensive principal component score of varus deformity, was extracted from the three indexes, and the total variance of the principal component interpretation was 76.60%. Multivariate logistics and linear regression analysis showed that after adjusting for age and BMI, LPW and PFC were positively correlated with K-L grading and varus deformity. FH was significantly and negatively associatedwith K-L grading and varus deformity (all P < 0.05).
Conclusions
Regular morphological changes take place in the lateral knee with varus OA, including lateral dislocation of the tibial plateau, proximal fibula bending, and upward movement of the fibular head. Changes in LPW, PFC, and FH could enable a more comprehensive assessment of varus knee OA occurrence, severity, and deformity.
Level of Evidence
Retrospective Study Level III