A review of the differences between normal and osteoarthritis articular cartilage in human knee and ankle joints

Abstract 

Background

Osteoarthritis (OA) is the most common joint disease yet its pathophysiology is still poorly understood. It is more prevalent in some lower limb joints than others; in particular the knee is more commonly affected than the ankle. Research into articular cartilage and OA has primarily focussed on using animal models. However, it is apparent that articular cartilage differs between species, so more research is concentrating on human cartilage.

Objective

This paper reviews recent studies that have been undertaken to elucidate the reasons for this, and to discover if the findings would alter the conception that articular cartilage is not capable of repair.

Method

Primary research papers into human knee and ankle cartilage published since 1997 have been reviewed.

Results

Differences in the structure, metabolism, physical properties and response to trauma have been found, implying that ankle cartilage may be more resistant to damage.

Conclusions

More research is needed before definitive conclusions can be reached, but the findings so far suggest that OA should not be accepted as the inevitable outcome of joint injury and individuals and practitioners, such as podiatrists, may be able to use simple measures to prevent or delay its onset.

Abbreviations: CII, Collagen type 2, ECM, Extracellular matrix, Fn-f, Fibronectin fragments, GAG, Glycosaminogen, Il, Interleukin, MMPs, Matrix metalloproteinases, MTPJ, Metatarsophalangeal joint, OA, Osteoarthritis, OP-1, Osteogenic protein-1, PG, Proteoglycan, TNF, Tumour necrosis factor

Keywords: Ankle, Articular cartilage, Knee, Osteoarthritis