Metallic wear in failed titanium-alloy total hip replacements: A histological and quantitative analysis

Abstract

This study involved thorough histological examination of peri prosthetic tissues in nine hips that had failed total arthroplasty. The prostheses were composed of titanium alloy (Ti-6Al-4V) and ultra-high molecular weight polyethylene. The time between insertion and failure varied from 11 to 57 months (mean time 33.5 months). Reasons for failure included aseptic loosening in 7 hips and infection in 2. Cement had been used in eight hips. On histological analysis an intense histocytic and plasmacell reaction was seen in the pseudocapsular tissue with extensive metallic staining of the lining cells. In fi ve hips a giant cell reaction with polyethylene debris and cement were seen. With atomic absorption spectrophotometry the following measurements were made, (mean levels found per gram of dry tissue and the normal value in parentheses): titanium 56-3,700 (mean 1,047; normal zero), aluminum 2.1-396 (mean 115; normal zero), vanadium 2.9-220 (mean 67; normal 1.2). The highest metal ion levels occurred in the hip prosthesis, which had been in the longest. The proportions of the three elements in the tissues refl ected that of the prostheses. Reasons suggested for failure of the hips included fi ve cases of vertical position of the acetabular component, three cases of poor cementing on the femoral side, two cases of infection and one case of a separation of a pure titanium sintered pad. The authors point out that femoral components made of titanium alloy may become toxic locally and lead to infection and loosening.