Self-reported knee and foot alignments in early adult life and risk of osteoarthritis

Authors


Abstract

Objective

To determine whether self-reported early adult life malalignment of knees or feet are risk factors for knee or hip osteoarthritis (OA).

Methods

Participants in the Genetics of Osteoarthritis and Lifestyle case–control database were sent a questionnaire (n = 3,022) containing line-drawing instruments for self-reported knee and foot alignment at ages 20–29 years. Respondents were categorized as having straight, valgus, or varus knee, and straight, toe-in, or toe-out feet. Radiographic criteria were used to define current isolated knee or hip OA, combined knee and hip OA, or non-OA controls. Odds ratios (ORs), adjusted ORs, and 95% confidence intervals (95% CIs) were calculated and logistic regression was performed.

Results

The response rate was 72%; 87.5% of responders (n = 1,901) completed the alignment questions. Increased risk of isolated knee OA occurred with early adult varus (adjusted OR 5.16, 95% CI 2.87–9.41) and valgus knees (adjusted OR 3.16, 95% CI 1.04–9.64). The positive association between knee OA and toe-in foot was explained by varus knee. There was an increased risk of combined knee/hip OA from varus (adjusted OR 4.52, 95% CI 2.39–8.53) and valgus knees (adjusted OR 3.07, 95% CI 0.99–9.54). Varus knee was associated with risk of medial tibiofemoral OA, whereas valgus knee was associated with risk of lateral tibiofemoral and lateral patellofemoral OA. Toe-out foot was associated with reduced medial patellofemoral OA. For knee OA, a multiplicative interaction analysis between occupational risks and varus/valgus yielded an ORint of 3.20 (95% CI 1.08–9.49).

Conclusion

Constitutional alignment of the leg in terms of varus or valgus knee or foot rotation may be a significant factor in determining development and distribution of knee but not hip OA.

Ancillary