Component Size Mismatch Of Metal On Metal Hip Arthroplasty: An Avoidable Never Event

Recent advances in hip replacement design, in particular the trend towards greater modularity in hip systems, have increased the risk of component size mismatch (CSM). CSM occurs when incorrectly sized femoral heads and acetabular cups are coupled together or when the dimensions of the paired stem trunnion and head differ to that intended by the manufacturer.

CSM is a serious, preventable patient safety incident of which the true prevalence is unknown as many cases are not detected. Retrieval analysis of failed MOM hip implants may offer a better understanding of how often CSM occurs and how it affects the integrity of the implant.