Ceramic femoral head fractures in total hip arthroplasty.

A failure analysis was performed of 4341 alumina ceramic heads articulating with 2693 alumina ceramic and 1464 polymer sockets implanted over 20 years (1974 to 1994). From 1974 to 1982, a mushroom shaped head with ceramic neck was used in 1069 cases, and from 1982 to 1994 a ball type head was used in 3272 cases. In the ceramic/ceramic cases, the average followup was 11 years, and in the polymer pairing cases, the average followup was 6 years. In ceramic self pairing with the mushroom shaped head, the fracture rate was 0.4% (5 of 1069). With the ball type head, the fracture rate was 0.06% (1 of 1763). In articulation with polymer sockets, only 1 head fracture occurred (0.07%). In the group of cases with ceramic/ceramic pairing, the reason for fracture was direct trauma in 4 cases, recurrent neck impingement in 2 cases, and fatigue failure in 1 case. The only case with ceramic head fracture in polymer pairing also was caused by direct trauma. Fractures of the alumina ceramic heads cannot be avoided, but the use of ball type neckless heads brought the fracture rate close to 0. Under the aspect of material safety, it seems to be possible to use the great advantage of the superior low wear of the alumina/alumina couple with negligible fracture risk.