Association of Wearable Sensor-Derived Gait Measures with Cartilage Damage over Two Years among Adults with or at Risk of Knee Osteoarthritis.

OBJECTIVE: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 to worsening cartilage damage. METHODS:We studied participants from the Multicenter Osteoarthritis Study (MOST) ages 45 to 90 years with, or at risk for, knee osteoarthritis (OA). Gait assessment used inertial measurement units (APDM, Inc) on the pelvis and ankles during a 20-m walk. Knee magnetic resonance imaging (MRI) was acquired at baseline and two years later. Cartilage damage worsening was assessed using MRI Osteoarthritis Knee Scores 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 1,703 participants (mean [±SD] age 61.4 [±9.4] years, 56% female). At two 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 two years. Interventions to shorten step length might reduce risk of worsening cartilage damage.