Fracture propagation propensity of ceramic liners during impingement-subluxation: a finite element exploration.

Although improvements in materials engineering have greatly reduced fracture rates in ceramic femoral heads, concerns still exist for liners. Ceramics are vulnerable to fracture due to impact and from stress concentrations (point and line loading) such as those associated with impingement-subluxation. Thus, ceramic cup fracture propensity is presumably very sensitive to surgical cup positioning. A novel fracture mechanics finite element formulation was developed to identify cup orientations most susceptible to liner fracture propagation for several impingement-prone patient maneuvers. Other factors being equal, increased cup inclination and increased anteversion were found to elevate fracture risk. Squatting, stooping, and leaning shoe-tie maneuvers were associated with the highest fracture risk. These results suggest that fracture risk can be reduced by surgeons' decreasing cup abduction and by patients' avoiding of specific activities.