Physical Activity Trajectories Following Anterior Cruciate Ligament Reconstruction Linked To Worsening Femoral Cartilage Composition

There is increasing evidence that time spent in moderate to vigorous physical activity (MVPA) is associated with knee osteoarthritis (KOA) development following anterior cruciate ligament reconstruction (ACLR). It remains unclear if distinct MVPA trajectories exhibited during the first 12 months post-ACLR are linked to deleterious changes in femoral articular cartilage composition linked to early KOA. PURPOSE: Identify distinct MVPA trajectories between 2 and 12 months post-ACLR and compare femoral cartilage composition changes preoperatively (preop) to 12 months post-ACLR between MVPA trajectory groups. METHODS: Physical activity was measured over 7 days in 51 individuals with primary, unilateral ACLR at 2, 4, 6, and 12 months post-ACLR using an ActiGraph GT9X monitor. Daily MVPA was calculated using Troiano cut points. Group-based latent trajectory modeling identified distinct MVPA trajectory groups. T1ρ magnetic resonance imaging was applied to evaluate cartilage matrix composition, with elevated T1ρ values indicating cartilage matrix degradation. Change in T1ρ (ΔT1ρ) was determined between preop and 12 months post-ACLR in the lateral (LFC) and medial femoral compartment. Differences in ΔT1ρ between groups were compared. RESULTS: We identified 2 MVPA trajectories (Figure 1) characterized as 1) a consistent MVPA group (n = 38, 57.9% female, age = 22.9 ± 5.0 yrs, BMI = 24.0 ± 2.9 kg/m2), and 2) an increasing MVPA group (n = 13, 61.5% female, age = 19.6 ± 2.9 yrs, BMI = 24.3 ± 4.4 kg/m2). The increasing MVPA group (ΔT1ρ = 5.78 ± 4.54 ms) demonstrated greater ΔT1ρ between preop and 12 months post-ACLR in the LFC than the consistent MVPA group (ΔT1ρ = 0.69 ± 5.86 ms, p = 0.01). CONCLUSION: Increased MVPA trajectories between 2 and 12 months post-ACLR may be linked to early KOA development in the first 12 months post-ACLR. Limiting high MVPA in the first 12 months post-ACLR may be beneficial for reducing early negative changes in cartilage composition linked to KOA development. Supported by: Arthritis Foundation, National Institute of Arthritis and Musculoskeletal and Skin Diseases (P30AR072580)