Domestic Meeting of the European Hip Society edition:8 location:Madrid, Spain date:11-13 June 2008
Femoral neck impingement with the acetabular component is a well known phenomenon in total hip replacement. Impingement with a polyethylene acetabular component may lead to increased wear and osteolysis, impingement with a ceramic on ceramic couple may cause breakage of the ceramic cup liner. With a metal on metal articulation (MOM) however the metal liner is much harder than the femoral component due to the presence of carbides. The metal cup liner will not break but levering of the neck against the cup may progress to femoral component loosening. In addition notching of the femoral neck generates metal debris and poses a risk for fracture of the neck of the femoral component.
Forty-eight patients less than 50 years old with 52 THR with a 28mm MOM articulation were followed for 5 years or more. Within 5 years following the index operation we observed notching of the femoral neck in 7 THR (13.5%) in this 28mm MOM articulation. In one patient impingement caused femoral component loosening requiring revision surgery.
Conclusions: We definitely discourage the use of small diameter MOM articulation in THR because of the risk of femoral neck impingement. This may lead to femoral neck notching, metal debris generation, femoral component loosening and poses a risk for femoral neck fracture.