Arthroplasty with a solid bone graft for protrusio acetabuli.

A high percentage of hips in patients with rheumatoid arthritis presenting for total joint replacement have protrusio deformity with extremely thin medial acetabular walls. Biomechanical principles suggest that, to prevent inward migration of the acetabular component, the prosthesis should be positioned laterally near the acetabular rim. To reinforce the medial wall, the femoral head is fashioned into a solid graft which is anchored against the medial wall as a plug, minimising the amount of cement used and making the use of wire mesh and restraining rings about the acetabulum unnecessary. A series of nine operations on seven patients is presented. Serial radiographs, tomograms and scintigrams taken after operation suggest satisfactory incorporation of the grafts, and no complications have been encountered in a follow-up period ranging from three months to two years.