Physical Activity Trajectories in the First Year following ACL Reconstruction and Links to Early Markers of...

Time spent in moderate-to-vigorous physical activity (MVPA) is linked to biomarkers associated with knee osteoarthritis development following anterior cruciate ligament reconstruction (ACLR). It remains unclear whether distinct MVPA trajectories exhibited during the first 12 months post-ACLR are linked to early markers of knee osteoarthritis.

To identify distinct MVPA trajectories between 2 and 12 months post-ACLR and compare tibiofemoral articular cartilage composition changes and patient-reported outcomes (PROs) between trajectory groups.

Device-measured MVPA was collected at 2, 4, 6, and 12 months post-ACLR in individuals with ACLR. MVPA trajectories were identified using group-based trajectory modeling. Cartilage composition was measured preoperatively and at 12 months post-ACLR using change in T1ρ (ΔT1ρ) magnetic resonance imaging relaxation times in the lateral (lateral femoral condyle [LFC], lateral tibia) and medial (medial femoral condyle, medial tibia) femoral and tibial compartments. The Knee Injury and Osteoarthritis Outcomes Score (KOOS) was used to assess PROs preoperatively and at 2, 4, 6, and 12 months post-ACLR. Differences in KOOS subscale scores and ΔT1ρ were compared between MVPA trajectory groups.

We identified a consistent MVPA (74.5%) and a high-increasing MVPA trajectory (25.5%). The high-increasing trajectory group engaged in more MVPA at all time points compared with the consistent group. The high-increasing trajectory group demonstrated greater ΔT1ρ in the LFC (i.e., deleterious changes in cartilage composition, P = 0.006) and higher KOOS sport compared with the consistent MVPA group ( P = 0.037).

Individuals between 2 and 12 months post-ACLR most commonly engage in the consistent MVPA trajectory. The high-increasing MVPA trajectory group demonstrated worsening LFC cartilage composition. These data indicate that high MVPA in the first 12 months post-ACLR may be linked to deleterious knee tissue changes but not worse PROs.