LAUSR

OBJECTIVE To determine if individuals with chronic ankle instability (CAI) demonstrate different talar cartilage T1ρ relaxation times compared to uninjured controls. DESIGN Fifteen CAI (21.13 ± 1.81 years, 4.00 ± 2.07 previous ankle sprains) and fifteen controls (21.07 ± 2.55 years, no previous ankle sprains) participated. CAI inclusion criteria was in accordance with the International Ankle Consortium guidelines. Greater T1ρ relaxation times were interpreted as greater degenerative changes. Participants were non-weight bearing for 30-minutes prior to scanning to unload the cartilage. Voxel by voxel T1ρ relaxation times were calculated from a five image sequence. Segmentation of the talar cartilage was performed manually using ITK-SNAP software. T1ρ relaxation time means and variability across the entire talus and in the anteromeidal, anterolateral, posteromedial, and posterolateral regions of interest (ROIs) were compared between groups using mean differences and effect sizes (ES) with their corresponding 95% confidence intervals (95%CI). RESULTS Individuals with CAI demonstrated higher T1ρ relaxation times (mean ± standard deviation) across the entire talus (CAI: 65.97 ± 10.45 ms, Control: 58.84 ± 7.68 ms; ES = 0.76, 95%CI = 0.02-1.50), in the anterolateral (ES = 1.00, 95%CI = 0.24-1.48), posteromedial (ES = 0.74, 95%CI = 0.01-1.49), and posterolateral region of interest (ES = 3.84, 95%CI = 2.63-5.04). The T1ρ relaxation time variability (mean ± standard deviation) also differed across the overall talus (CAI: 32.78 ± 4.06 ms, Control: 28.23 ± 4.45 ms; ES = 1.04, 95%CI = 0.28-1.80), in the anteriolateral, (ES = 1.07, 95%CI = 0.31, 1.84) and posteriolateral (ES = 1.00, 95%CI = 0.24-1.75) ROIs. CONCLUSIONS Individuals with CAI demonstrate greater T1ρ relaxation times and higher T1ρ variability compared to uninjured controls. This finding supports the existing literature illustrating early degenerative joint tissue changes consistent with early onset posttraumatic osteoarthritis in individuals with CAI.