Constitutional alignment of the leg (varus or valgus knee or foot rotation) may be a significant factor in determining the development and distribution of knee osteoarthritis (OA) but not isolated hip OA, according to researchers at Academic Rheumatology, University of Nottingham, City Hospital, in Nottingham, UK. McWilliams and associates1 sent participants in the Genetics of Osteoarthritis and Lifestyle case-control database a questionnaire that contained line-drawing instruments for self-reported knee and foot alignment at ages 20 to 29 years. Respondents were categorized as having straight, valgus, or varus knee and straight, toe-in, or toe-out foot. Radiographic criteria were used to define current isolated knee or hip OA, combined knee and hip OA, and non-OA controls.
An increased risk of isolated knee OA was evident with early adult varus and valgus knees. A positive association between knee OA and toe-in foot was explained by varus knee. There was an increased risk of combined knee and hip OA with varus and valgus knees. Varus knee was associated with the risk of medial tibiofemoral OA and valgus knee with the risk of lateral tibiofemoral and lateral patellofemoral OA. In addition, toe-out foot was associated with reduced medial patellofemoral OA.
