FRACTURE OF THE FEMORAL-HEAD AFTER CERAMIC-ON-POLYETHYLENE TOTAL HIP-ARTHROPLASTY

Four of 184 ceramic femoral heads that the authors used in total hip a rthroplasty fractured from 5 to 9 months after surgery. A polyethylene -lined acetabular component was used in all cases. The fracture rate, 2.2%, was much higher than previously reported for ceramic head fractu res when used with a polyethylene cup. The fractures occurred during n ormal daily activities. Possible causes included manufacturing defects , neck length (short in all cases), bearing diameter (28 mm in all cas es), cone-trunnion mismatch, excess hoop stresses from impaction, or m aterial deterioration. All patients were treated by removal of debris, wide excision of capsular tissue containing tiny abrasive fragments, exchange of the modular polyethylene liner, and implantation of a coba lt-chrome femoral head. The trunnion had been somewhat damaged by rela tively brief exposure to the ceramic particles in every case. The auth ors' experience suggests that ceramic femoral heads be used with cauti on.