Associations among ankle cartilage composition and ultrasound based measures of cartilage health in those with chronic ankle instability.

INTRODUCTION/OBJECTIVES: Chronic ankle instability (CAI) is a significant contributor to articular degeneration at the ankle. Identifying early pathogenic articular changes is limited to compositional MRI techniques which are not clinically feasible. Ultrasound is cost-effective, and echo-intensity (EI) measures may be an indicator of cartilage health. Therefore, we aimed to (i) quantify changes in ultrasound measures of talar cross-sectional area (CSA) and EI following standardized loading protocols and recovery periods and (ii) quantify the associations between ultrasound measures and talar and subtalar cartilage composition in those with CAI.

METHOD

Thirty-seven individuals with CAI (22.6 ± 4.2 years, 3.8 ± 2.7 sprains) completed a T1ρ MRI and two ultrasound assessments. The talar cartilage was imaged with US before, immediately after, 15-min after, and 30-min after separate static and dynamic loading protocols.

RESULTS

Ultrasound outcomes acutely changed in response to load (p < 0.05). The CSA and EI means remained altered throughout the recovery period (p < 0.05) while the EI standard deviation recovered to baseline levels. Greater subtalar T1ρ relaxation times (i.e., worse composition) were significantly (p ≤ 0.05) associated with lower thickness (r = -0.409) and EI variability (r = 0.419) baseline values, greater EI mean responses to load (r = -0.558), and smaller EI mean recoveries (r ≥ -0.360) which all suggest worse cartilage health.

CONCLUSIONS

In those with CAI, ultrasound-based outcomes acutely respond to load but have unique recovery patterns. Ultrasound may serve as a valid clinically accessible tool to evaluate ankle cartilage composition, particularly Subtalar cartilage. Key Points • In those with CAI, talar cartilage CSA and EI, measured via ultrasound, are acutely sensitive to load but recovery patterns are outcome specific. • Ultrasound measures of thickness and EI may serve as valid clinically accessible surrogates of subtalar cartilage composition.