Frictional response of articular cartilage containing crystals.

Many joint diseases are associated with the deposition of crystals in articular cartilage. Three main types are commonly found: calcium pyrophosphate, calcium hydroxyapatite and monosodium urate. The effects of these articular crystals on the frictional properties and the surface condition of the articular cartilage were studied. A total of 43 cartilage specimens cut from 19 post-mortem knee joints have been tested in purpose-designed apparatus. The results show that a high friction coefficient and a high level of crystal deposition tend to occur with a worsening of the surface quality of the articular cartilage.