T2 Relaxation Values of the Talar Trochlear Articular Cartilage: Comparison Between Patients With Lateral Instability of the Ankle Joint and Healthy Volunteers.

OBJECTIVE

The purpose of this study was to evaluate the difference between the T2 relaxation values of the talar trochlear cartilage in patients with lateral instability of the ankle joint and the values in healthy volunteers.

MATERIALS AND METHODS

A retrospective assessment was conducted of images from 13 MRI examinations of the ankles of 12 patients who underwent lateral ankle ligament repair with an arthroscopically proven normal talar trochlear cartilage. Thirteen ankle MRI examinations of 12 healthy age- and sex-matched volunteers were prospectively performed. Two radiologists independently measured the T2 relaxation values of the talar trochlear cartilage in two layers (superficial and deep) in the following six compartments: medial anterior (M1), medial middle (M2), medial posterior (M3), lateral anterior (L1), lateral middle (L2), and lateral posterior (L3). The T2 relaxation values of patients were compared with those of healthy volunteers.

RESULTS

Both readers found that the mean T2 relaxation values of all six compartments of the superficial layer were significantly higher in patients than in control subjects. For reader 1, the M1 findings were 46.2 for patients and 39.6 for healthy volunteers; M2, 50.4 and 41.1; M3, 52.1 and 46.2; L1, 43.1 and 37.9; L2, 47.8 and 41.8; and L3, 53.8 and 49.8. For reader 2, the M1 findings were 45.0 and 40.2; M2, 48.8 and 41.1; M3, 53.2 and 45.6; L1, 42.8 and 38.5; L2, 48.0 and 42.1; and L3, 55.0 and 49.0 (p < 0.05). For the deep layer, the mean T2 relaxation values of M2 (patients, 32.6; volunteers, 27.8 [p = 0.004]) and M3 (patients, 38.3; volunteers, 35.0 [p = 0.046]) for reader 1 and M2 (patients, 31.6; volunteers, 28.7 [p = 0.041]) for reader 2 were significantly higher in patients than in control subjects. Intraobserver and interobserver variability were excellent, except for interobserver variability for M1 deep (0.79) and L1 deep (0.75).

CONCLUSION

The T2 relaxation values of arthroscopically proven normal talar trochlear cartilage of patients with lateral instability were higher than those of healthy volunteers, especially in the superficial layer and the M2 deep layer.