Non-traumatic osteonecrosis of the femoral head
is a potentially devastating condition, the prevalence of which
is increasing. Many joint-preserving forms of treatment, both medical
and surgical, have been developed in an attempt to slow or reverse
its progression, as it usually affects young patients. However, it is important to evaluate the best evidence that is
available for the many forms of treatment considering the variation
in the demographics of the patients, the methodology and the outcomes
in the studies that have been published, so that it can be used
effectively. The purpose of this review, therefore, was to provide an up-to-date,
evidence-based guide to the management, both non-operative and operative,
of non-traumatic osteonecrosis of the femoral head. Cite this article:
Pathological assessment of periprosthetic tissues is important, not only for diagnosis, but also for understanding the pathobiology of implant failure. The host response to wear particle deposition in periprosthetic tissues is characterised by cell and tissue injury, and a reparative and inflammatory response in which there is an innate and adaptive immune response to the material components of implant wear. Physical and chemical characteristics of implant wear influence the nature of the response in periprosthetic tissues and account for the development of particular complications that lead to implant failure, such as osteolysis which leads to aseptic loosening, and soft-tissue necrosis/inflammation, which can result in pseudotumour formation. The innate response involves phagocytosis of implant-derived wear particles by macrophages; this is determined by pattern recognition receptors and results in expression of cytokines, chemokines and growth factors promoting inflammation and osteoclastogenesis; phagocytosed particles can also be cytotoxic and cause cell and tissue necrosis. The adaptive immune response to wear debris is characterised by the presence of lymphoid cells and most likely occurs as a result of a cell-mediated hypersensitivity reaction to cell and tissue components altered by interaction with the material components of particulate wear, particularly metal ions released from cobalt-chrome wear particles. Cite this article: Professor N. A. Athanasou. The pathobiology and pathology of aseptic implant failure.
