Study Design Case-control.

Objectives Examine femoral cartilage thickness in physically active young adults with chronic ankle instability (CAI).

Background A history of lateral ankle sprain that occurred early in life can lead to significant negative impact on joint health. Inadequate energy attenuation capability of the knee joints during a functional task have been observed in young adults with CAI, which can increase compressive impact force at the knee joint, causing early cartilage degeneration at the knee joint. However, a study designed specifically to compare femoral cartilage thickness in those with and without CAI is lacking.

Methods and Measures Fourteen participants with CAI (21.38±2.47 years;174.25±5.30 cm;67.12±7.6 kg) and 20 healthy controls (21.34±1.43 years;173.17±5.91 cm;63.78±6.80 kg) volunteered for this current study. Participants with CAI were required to have experienced their first-time lateral ankle sprain before they turned 18 years old. All participants were free from knee joint injury. With the knee held in maximum flexion, medial and lateral femoral cartilage thickness was assessed bilaterally using a portable ultrasound unit. Using ultrasonography, distal femoral cartilage thickness (mm) was measured at the midpoint of the intercondyle notch as well as 10 mm apart in the medial and lateral directions. Independent t-tests were utilised to compare medial and lateral femoral cartilage thickness of each side between the CAI and control groups. Significance was set a priori at p<0.05.

Results There were no significant differences in intercondylar, medial, and lateral femoral cartilage thickness of right and left sides between the CAI and control groups (p<0.05).

Conclusions The presence of CAI did not alter femoral cartilage thickness in physically active young adults. To identify more specific changes in cartilage composition and structure at the distal femur, further studies are needed to examine the effects of loading on changes in femoral cartilage deformation in CAI population.