The evolution of the trunnion.

Implant modularity has recently come under increasing scrutiny due to concerns regarding wear, corrosion and potential adverse reactions to metal debris. This review outlines the evolution and development of the femoral stem trunnion and relates this to contemporary issues now encountered.Despite different manufacturers producing what appear to be similar trunnion designs, there is still a lack of standardisation, with small but significant design variations. Wear and corrosion is certainly not a new phenomenon, but recent changes in design and the use of larger metal head sizes has potentially made the problem more prevalent. These issues along with steps to avoid these problems are discussed.