Change in knee cartilage T2 in response to mechanical loading

Purpose: To assess the clinical feasibility of magnetic resonance (MR) imaging with a mechanical loading system for evaluation of load-bearing function in knee joints using cartilage T2 as a surrogate of cartilage matrix changes. Materials and Methods: Sagittal T2 maps of the medial and lateral femorotibial joints of 22 healthy volunteers were obtained using 3.0T MR imaging. After preloading for 6-9 minutes, MR images under static loading conditions were obtained by applying axial compression force of 50% of body weight during imaging. T2 values of the femoral and tibial cartilage at the weight-bearing area were compared between unloading and loading conditions. Results: Under loading conditions, mean cartilage T2 decreased, depending on location of the knee cartilage. For the femoral side a significant decrease in T2 with loading was observed only at the region in direct contact with the opposing tibial cartilage, in the medial femoral cartilage (5.4%, P < 0.0005). For the tibial side a significant decrease in T2 with loading was widely observed in the medial and lateral joint, at regions both covered and not covered by the meniscus (4.3%-7.6%, P < 0.005). Conclusion: MR imaging with mechanical loading is feasible to detect site-specific changes in cartilage T2 during static loading.