Association of wearable‐sensor derived gait measures with cartilage damage over 2 years in the Multicenter Osteoarthritis Study

Purpose Gait affects knee loading. Modifying gait could reduce load and protect against cartilage loss. Our objective is to look for modifiable gait parameters and determine their relation with worsening cartilage damage. Methods We studied participants from the Multicenter Osteoarthritis Study (MOST) age 45‐90 with, or at risk for, knee osteoarthritis (OA). Gait assessment used inertial measurement units (APDM) on the pelvis and ankles during a 20‐meter walk. Knee magnetic resonance imaging (MRI) images were acquired at baseline and 2 years later. Cartilage damage worsening was assessed using MRI Osteoarthritis Knee Scores (MOAKS) in 14 knee subregions. We examined change (yes/no) in each subregion. We used ensemble machine learning to discriminate subregions with and without cartilage damage. Predictors tested included gait variables, radiographic OA, baseline cartilage damage, age, sex, height, weight, depressive symptoms, and race/clinic site. Data were split 70% training and 30% test sets. We identified the 10 variables that, across 100 repetitions, most frequently contributed to risk of damage. We used G‐computation to evaluate causal risk differences of worsening cartilage damage for each variable. Results We studied 1703 participants (mean age 61.4 [SD: 9.4] years, 56% female). At 2 years, 46% had worse cartilage damage in at least one knee subregion. Of gait variables, longer step length was associated with increased risk of damage, especially in knees with more baseline damage. Conclusion Longer step length was associated with worse cartilage damage over 2 years. Interventions to shorten step length might reduce risk of worsening cartilage damage.