Study Design Correlational study.

Objectives To determine if T1ρ MRI is associated with ultrasonography(US) measurements of talar cartilage in those with chronic ankle instability (CAI).

Background Recurrent ankle injuries are a leading cause of post-traumatic ankle osteoarthritis (PTAOA). Reduced proteoglycan density (PGD) measured using T1ρ MRI is an early indicator of PTOA. US has been used to monitor joint health in people with knee OA, but the relationship between US and T1ρ MRI in CAI patients remains unknown.

Methods and Measures 9 CAI patients participated. T1ρ MRI was performed using a Siemens Magnetom TIM Trio 3T scanner. Segmentation of the T1ρ MRI images was done using ITK-SNAP software. Four regions of interest (ROI): anteromedial (AM), anterolateral (AL), posteromedial (PM), and posterolateral (PL) were identified. Talar cartilage thickness was measured using ultrasound while patients were positioned supine on the examination table. The ultrasound transducer was positioned for a longitudinal view over the medial, middle, and lateral aspect of the talocrural joint. The thickness was measured using the ImageJ software program at the midpoint of each image. Correlations between mean T1ρ relaxation times and cartilage thickness values in each ROI were analysed using Pearson correlation coefficients. Statistical significance was set at p<0.05 for all analyses.

Results A significant correlation between T1ρ relaxation time (r=0.786, p=0.012) in the PL ROI and middle talar cartilage thickness was noted and a trend was noted for middle talar cartilage and T1ρ relaxation times in the PM (r=0.647, p=0.060) ROI. No other significant correlations were found.

Conclusions Positive correlations between T1ρ relaxation times (higher T1ρ=less PGD density) and greater talar cartilage thickness may be explained by increased water content (swelling) in the cartilage due to greater cartilage breakdown. US measurements may be able to detect early degenerative change in CAI patients but further research is needed.