Application of real-time ultrasound swelling measurement in articular cartilage research

Articular cartilage (AC) is a biological weight-bearing tissue covering the bone ends of articulating joints. Under normal conditions the proteoglycan elasticity keeps balance with the collagen tension in articular cartilage. Subtle changes of this balance may lead to the degeneration of AC. Quantification of these swelling effects in AC, particularly in superficial zones, can be used to characterize degenerative changes associated with osteoarthritis. This paper introduces a new real-time ultrasound swelling measurement system used for investigation of AC. The system with 50MHz ultrasound was used to monitor in real-time the inhomogeneous transient and depth-dependent swelling behavior of bovine patellar AC which was bathed by trypsin and 0.15M saline solution respectively. The experimental results show that the method of real-time ultrasound measurement provided a particular tool to study the degeneration of articular cartilage. This technique can be potentially used for early diagnosis of cartilage degeneration in vivo through an arthroscope.