Long-term effect of removal of knee joint loading on cartilage quality evaluated by delayed gadolinium-enhanced magnetic resonance imaging of cartilage.

ABSTRACT

OBJECTIVE: Ankle fracture patients were used as a model to study the long-term effect of the removal of joint loading on knee cartilage quality in human subjects. DESIGN: The knees of 10 patients with ipsilateral ankle fractures were investigated using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) at the time of ankle injury. After 6 weeks' prescribed unloading of the affected leg, but no restrictions regarding knee movement, the cast was removed from the ankle and the patient underwent a second dGEMRIC examination. Physiotherapy was then initiated. A third dGEMRIC examination was performed 4 months after remobilization, and a final examination 1 year after the injury. RESULTS: Baseline T1Gd values for the 10 patients were within a narrow range. No significant change in mean T1Gd was observed after 6 weeks' prescribed unloading, but the T1Gd range had increased significantly. Four months after remobilization, the mean T1Gd was significantly lower than in the previous examinations, and the range remained significantly broader than at baseline. At the 1-year follow-up, the mean T1Gd was almost identical to the value after remobilization, and the T1Gd range still showed a significant increase compared to the baseline investigation. CONCLUSIONS: Removal of knee cartilage loading for 6 weeks resulted in a measurable effect on the cartilage matrix, as evidenced by a broader T1Gd range. A decrease in mean T1Gd was observed 4 months after remobilization. These differences persisted a year after injury compared to baseline.