Varus knee alignment was correlated with radiographic indicators of the severe knee osteoarthritis (OA), including joint space narrowing and Kellergan-Lawrence (K-L) grading scale, in a retrospective cross-sectional analysis of patients in Korea.
Knee alignment has been implicated as a biochemical factor influencing the development and progression of knee OA. Malalignment has been linked to decreases in knee cartilage volume, radiographic progression of tibiofemoral OA, and patellofemoral OA. Varus knee alignment has also been tied to knee pain in more advanced cases of OA.
Thinning of the articular cartilage, a marker for OA progression, can be assessed with joint space width (JSW). The K-L grading scale incorporates features of the knee radiograph to assess the severity of knee osteoarthritis.
Dr Gun-Il Im, MD, of the Department of Orthopedics at Dongguk University Ilsan Hospital in Goyang, Republic of Korea, and colleagues conducted a cross-sectional study to explore the relationship between static varus knee alignment, joint space narrowing, K-L grade, and other radiographic measures of knee OA.
Weight-bearing anteroposterior (AP) radiographs were obtained on 251 Korean participants with symptoms and radiographic signs of OA to calculate knee alignment. The researchers assessed potential correlations between knee alignment and JSW and K-L grades.
The investigators found varus knee alignment was negatively correlated with JSW at the patellofemoral joint (r=0.168, P=.0008), the medial tibiofemoral joint in 45 degree flexion (r=-0.476, P=.0001), and the medial tibiofemoral joint in extension (r=0.460, P=.0001).
Similarly, multiple linear regression demonstrated varus alignment was negatively associated with joint space narrowing at medial tibiofemoral joints in both 45 degree flexion Posterior-anterior (PA) view and extension on AP view (P=.0001, both). This association was not observed for the patellofemoral JSW (P=.13).
Finally, analysis of covariance demonstrated significantly greater varus alignment in patients with K-L grade 4 compared to participants with K-L grades 1 to 3 (P=.0001 for all three views).
Summary and Clinical Applicability
The investigators in this cross sectional study found a negative association between varus knee alignment and medial tibiofemoral joint space width. Varus alignment was more prevalent in participants with K-L grade 4 tibiofemoral and patellofemoral joints.
The authors write, “The current study provides further evidence of the strong association of knee alignment to OA severity grades, and also offers a valuable reference from a Korean population in addition to already reported Chinese and Japanese data.”
Limitations and Disclosures
The authors note several limitations including its retrospective design, a small sample size for valgus alignment, and a lack of longitudinal data. However, the results suggest an association between knee alignment and OA severity in this population.
This study was supported by the Medical Technology Development Program of the National Research Foundation, Republic of Korea
1. Im GI, Kim MK, Lee SH. Relationship between knee alignment and radiographic markers of osteoarthritis: a cross-sectional study from a Korean population. Int J Rheum Dis. 2016;19(2):178-83.