Self-reported knee malalignment in early adult life as an independent risk for knee chondrocalcinosis

To determine if self-reported current and early adult life knee malalignment is associated with knee chondrocalcinosis (CC).

A case-control study embedded in the Genetics of Osteoarthritis and Lifestyle (GOAL) study was performed. A validated self-reported line-drawing instrument was mailed to 3,022 participants of GOAL, inquiring about knee malalignment (straight, valgus, varus) in their third decade (20s) and currently. Self-reported weight in 20s and present weight and height measured at the initial visit were used to calculate body mass index (BMI) in 20s and currently. Occupational risk was present if participants self-reported mechanically demanding activities in their longest held job. Cases were participants with radiographic CC at any tibiofemoral (TF) joints. Osteoarthritis was defined as a Kellgren/Lawrence score of ≥3 at TF joints or patellofemoral joints. Odds ratio (OR), adjusted OR, and 95% confidence interval (95% CI) were calculated for associations with knee CC.

A total of 2,167 participants responded to the questionnaire, of which 7.5% respondents had knee CC. Knee CC was associated with self-reported varus (adjusted OR 1.77 [95% CI 1.05, 2.98]) and any knee malalignment in 20s (adjusted OR 1.64 [95% CI 1.02, 2.64]). This association was not restricted to the mechanically loaded TF compartment. There was no association between current knee malalignment and knee CC. Age (adjusted OR 1.73 [95% CI 1.36, 2.19]) and knee OA (adjusted OR 2.88 [95% CI 1.89, 4.38]) were associated with knee CC. There was no association between BMI in 20s (adjusted OR 1.14 [95% CI 0.92, 1.42]), occupational risk (adjusted OR 1.32 [95% CI 0.94, 1.85]), and knee CC.

Early life knee malalignment, predominantly varus, is an independent risk factor for knee CC. This association is not restricted to the mechanically loaded compartment, implying a generalized predisposition throughout the knee.