Surgical implants. Physiological response.

Following the surgical insertion of all prosthetic implants, an identical sequence of events occurs, although the magnitude of each response is variable. Initially, to maintain hemostasis, the coagulation system is stimulated and platelet activation occurs. Within minutes, leukocytes accumulate in an attempt to neutralize the foreign body. Although these phagocytic cells are generally unsuccessful at breaking down the biomaterials comprising an implant, macrophages coalesce and wall-off the foreign body from surrounding tissues. Once the inflammatory response is quiescent, fibroblasts invade the granuloma, lay down connective tissue and contract to minimize the volume occupied by the implant. Although most implant patients experience uneventful recoveries, complications resulting from chronic activation of the inflammatory response or the mechanisms involved in maintaining hemostasis can occur.