Clinical Review Science, medicine, and the future

Treating joint damage in young people

BMJ 2000; 320 doi: http://dx.doi.org/10.1136/bmj.320.7249.1585 (Published 10 June 2000) Cite this as: BMJ 2000;320:1585
  1. George Bentley, professor of orthopaedic surgery ([email protected])a,
  2. Tom Minas, clinical instructor in orthopaedic surgeryb
  1. a Institute of Orthopaedics, Royal National Orthopaedic Hospital, Stanmore HA74LP
  2. b Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
  1. Correspondence to: G Bentley

    Nearly a quarter of all severe ligament or capsular knee injuries that result in a haemarthrosis are associated with cartilage damage.1 2 Breakdown of the cartilage from trauma or disease results in severe pain and disability and may progress to early osteoarthritis. In young patients this cannot be treated by joint replacement because of the risks of early loosening and “wearing out” of the prosthesis after about 10 years. This article details some of the new techniques that are being developed to restore painless joint function and possibly prevent osteoarthritis.

    Methods

    Our review is based on our personal experience of laboratory and clinical methods of repair of articular cartilage and a review of relevant current literature. We also included studies assessing outcome, the economics of surgery, and patients' quality of life and data from the proceedings of specialist societies.

    Cartilage structure

    The articular cartilage that lines joints is tough and resilient. It is essentially composed of a type II collagen sponge supported by water held in place by proteoglycans produced by the chondrocytes embedded in the matrix. The collagen fibres are firmly embedded in the subchondral bone, giving stability to the cartilage. The fibres are arranged as overlapping leaves arising from the subchondral bone that rise to the surface and then bend over to form arches. The proteoglycans and cells are embedded within the collagen fibres (fig 1).

    Fig 1.

    Spatial relations of collagen, proteoglycans, and cells in cartilage

    Proteoglycans are long chain polysaccharides linked to hyaluronate that are negatively charged and hold water within the cartilage by osmotic pressure, thus maintaining the tension of the collagen mesh. However, if the proteoglycans are damaged by trauma or by other agents such as enzymes in inflammatory disease or infection then the proteoglycan structure disintegrates and the water holding capacity is lost, and progressive breakdown …

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