Risk factors for ceramic liner fracture after total hip arthroplasty.

The aim of this study was to detect risk factors for ceramic liner fractures. 26 cementless ceramic on ceramic (COC) total hip arthroplasties (THA) revised because of ceramic liner fracture in 24 patients were compared with 49 well-functioning COC THA performed in 49 patients. Demographic parameters, type of ceramic of the liner, size and neck length of the femoral head, cup abduction angle, cup anteversion, femoral off-set, height of the centre of rotation and the incidence of noisy hips during follow-up examination were compared. A greater number of cups placed outside the optimal range of cup anteversion was found in the fracture group (p = 0.03). An audible noise was detected in 21 cases (80.7%) in the fracture group and in 3 cases (6.1%) in the non-fracture group (p = 0.001). A cup anteversion angle out of the optimal range of 15˚+/-10˚ was found to be a risk factor for ceramic liner fracture and the presence of a noisy hip frequently anticipated the failure. In our opinion neck-to-cup impingement with head subluxation and edge loading on the liner rim could have an important role in the onset of noise and subsequent liner failure, and cup malposition contributes to this mechanism of failure.