A review of aseptic loosening in total hip arthroplasty

Total hip arthroplasty has grained worldwide acceptance over the last few d ecades in humans and in dogs. Although long-term success is high in most st udies, aseptic loosening of components is still a serious complication. Ase ptic loosening can affect either the acetabular or femoral component of bot h cemented and cementless systems. The process is usually characterized by an interface membrane which develops between the adjacent bone and bone cem ent of the prosthesis, or in cementless components, between the bone and th e implant itself. The process leading to the formation of this interface me mbrane and its function is still unclear; although much has been written ab out this topic in recent years. Biomechanical factors including: prosthesis design and material composition and cellular mechanisms such as signaling pathways of cytokines, local mediators or matrix metalloproteinases, have b een incriminated to be responsible for the process. None of these factors, alone, have been conclusively proven to be the cause of aseptic loosening.