Bony ingrowth fixation of the acetabular component in canine hip joint arthroplasty.

Five mature dogs were studied five to eight months after insertion of a newly designed acetabular component that eliminates the use of bone cement in total hip arthroplasty (THA). The component was hemispheric, with a layer of porous metal on its outside surface. It initially was fixed to the innominate bone by screws passed through projections from the edge of the metal substrate. When the dogs were killed five or eight months after implantation, all components were fixed rigidly to the bone. Bony ingrowth covered an average of 53% of the porous surface of the implant, penetrating three layers of balls.