[Clinical fracture of joint prostheses]

Ten Ti6Al4V joint prostheses, including 8 hips and 2 knees, were fractured after 1 to 13 years in vivo service following the primary arthroplasty. The metallographs and electronic microscopies, taken from the retrieved components, demonstrated that there are typical characteristics of stress corrosion fatigue. The excessive chemical content of raw material, the presence of interior defects, such as inclosures and porosities, incorrect design features, which violate biomechanic principles, the overheating and improper surface finishing of the parts, and the clinical varus positioning of the hip stem contribute to the device failure. Policies are proposed to overcome this problem. Among them are drawing national mandatory standards on surgical implants, taking strigent administration measures to ensure the quality of joint prostheses and the establishment of training centers for arthroplasty.