Change in knee cartilage T2 in response to mechanical loading

Area of Science:

• Biomedical Engineering
• Radiology
• Orthopedics

Background:

• Assessing knee joint load-bearing function is crucial for diagnosing cartilage degeneration.
• Cartilage T2 values serve as a sensitive indicator of matrix changes.
• Developing non-invasive imaging techniques for in-vivo evaluation is a key research area.

Purpose of the Study:

• To evaluate the clinical feasibility of magnetic resonance (MR) imaging combined with a mechanical loading system.
• To assess load-bearing function in knee joints by using cartilage T2 as a surrogate for matrix changes.
• To investigate site-specific alterations in cartilage T2 under static loading conditions.

Main Methods:

• Sagittal T2 maps of the medial and lateral femorotibial joints were acquired from 22 healthy volunteers using 3.0T MR imaging.
• Static loading conditions were applied, simulating 50% of body weight axial compression force during imaging after preloading.
• T2 values of femoral and tibial cartilage in weight-bearing areas were compared between unloading and loading states.

Main Results:

• Mean cartilage T2 values decreased under loading conditions, with location-dependent variations.
• A significant decrease in femoral cartilage T2 was observed (5.4%, P < 0.0005) specifically at the load-bearing contact region with the tibia.
• Significant decreases in tibial cartilage T2 were widespread (4.3%-7.6%, P < 0.005) in both medial and lateral compartments, irrespective of meniscal coverage.

Conclusions:

• MR imaging with mechanical loading is clinically feasible for evaluating knee joint load-bearing function.
• This technique can detect site-specific changes in cartilage T2 values during static loading.
• The findings support the use of cartilage T2 as a biomarker for assessing cartilage matrix integrity under physiological load.