Changes in acoustic parameters at 30 MHz of human and bovine articular cartilage following experimentally-induced matrix degradation to simulate early osteoarthritis

Matrix degradation and proteoglycan loss in articular cartilage is a feature of early osteoarthritis. To determine the effect of matrix degradation and proteoglycan loss on ultrasound propagation in cartilage, we used papain and interleukin-1α to degrade the matrix proteoglycans of human and bovine cartilage respectively. There is also minor collagen alteration associated with these chemical degradation methods. We compared the speed of sound and frequency dependent attenuation (20 to 40 MHz) of control and experimental paired samples. We found that a loss of matrix proteoglycans and collagen disruption resulted in a 20-30% increase in the frequency dependent attenuation and a 2% decrease in the speed of sound in both human and bovine cartilage. We conclude that the attenuation and speed of sound in articular cartilage are sensitive to experimental modification of the matrix proteoglycans and collagen. These findings suggest that ultrasound can potentially be used to detect morphologic changes in cartilage associated with the progression of osteoarthritis