ABSTRACT
Osteoarthritis (OA) is the most common musculoskeletal disorder affecting over 8 million people in the UK. OA primarily involves the knee, hip, hand, spine and foot. The wrists, shoulders and ankles are less frequently affected. The clinical features of OA include joint pain, tenderness, limited movement, crepitus, occasional effusion, deformity and variable degrees of low-grade inflammation without systemic effects. The macroscopic changes of articular cartilage in OA are softening, fibrillation, pitting, erosion (ulceration), delamination and eventually denudation to subchondral bone. Loss of the large aggregating proteoglycan, aggrecan, is a consistent and early biochemical finding. The ultrastructure and organization of the type II collagen mesh is significantly disturbed. Fibre size and orientation become variable and disordered. An increase in water content is one of the earliest detectable changes in OA, albeit by only a few per cent over normal cartilage. The biochemical and structural alterations in the matrix of OA cartilage result in inferior mechanical properties compared to normal articular cartilage.
