The natural degeneration course in the T1rho values of normal knee cartilage.

The purpose of our study is to investigate whether there is an age-related change in T1 rho values and to evaluate the effects of weight bearing on age-related increase in T1 rho values of normal cartilage. Thirty-two asymptomatic patients were examined using a 3.0T MRI to determine knee cartilage T1 rho values. Femorotibial and patella cartilage was defined as weight-bearing cartilage (WB-C) and non-weight-bearing cartilage (NWB-C), respectively. The femoral cartilage was divided into weight-bearing (WB-P) and less-weight-bearing (LWB-P) portions. Pearson's correlation coefficient and single regression analysis were used to assess the relationship between cartilage T1 rho values and age. The slopes of the regression lines of cartilage T1 rho values and age were compared between WB-C and NWB-C and between WB-P and LWB-P. Cartilage T1 rho values correlated positively with aging for all cartilage regions and all age groups (p<0.001). In the medial femoral cartilage, the age-related increase in T1 rho values was significantly greater for WB-P than for NWB-P (p<0.05). For several cartilage regions, this increase was greater for WB-C than for LWB-C (p<0.05). The T1 rho value is very sensitive to age-related cartilage degeneration and weight bearing-related degeneration, and hence may be a very sensitive and useful measure for the early diagnosis of osteoarthritis.