Sodium NMR evaluation of articular cartilage degradation.

One of the first effects of degenerative osteoarthritis is the loss of proteoglycans from the matrix of articular cartilage. Using a model of osteoarthritic change where the cartilage has been enzymatically degraded with trypsin, the sodium NMR characteristics of the cartilage were determined as a function of changes in the proteoglycan content. The results demonstrate that the single quantum sodium signal decreases as the proteoglycan content of the cartilage matrix decreases. In addition, the relaxation characteristics of the sodium change such that the T1 is longer, the T2s is longer, and the T2f is shorter. Short echo-time, T1-weighted sodium images are presented which demonstrate that this information may be utilized to detect the loss of proteoglycans from articular cartilage.