COMPERATIVE REVIEW OF ACETABULAR REVISION TECHNIQUES OF IMPACTION GRAFTING WITH AND WITHOUT RECONSTRUCTION CAGES

Abstract

The most challenging aspect of acetabular revision is the management of bone loss compromising implant fixation and stability. Several options, including both nonbiologic and biologic fixation, are available for acetabular revision. Biologic fixation is considered the best solution for revision surgery because it aims to restore the detoriated bone stock by using structural or cancellous allografts and a cemented polyethylene cup with impaction grafting with or without an antiprotrusio cage. With this technique, reliable and durable fixation of cemented acetabular components depend on the incorporation of allografts.

Impaction grafting with use of morselized bone is a biological fixation alternative as defined by Sloof in 1984. He reported 94% survival in 11 years. Best results of this technique are obtained in contained or cavitary defects because the skeleton, while weakened, is basically intact. In these defects the anterior and posterior columns and the peripheral supporting bone for the acetabular component are intact. However, uncontained, or segmental, defects are more of a challenge. If the patient has a large segmental defect and there is no possibility of placing the implant against host bone or of restoring nearly normal anatomy, then the use of a structural bone graft may be indicated.

In our revision arthroplasty series, despite the success of impaction grafting on the femoral side and on cavitary defects of the acetabulum, we had early loosening in segmentary defects with mesh or structural allograft reconstruction of the acetabular wall and impaction. Retrospectively, we have compared the survival of acetabular cup revisions with impaction grafting technique with or without reconstruction cages in 40 hips of 39 patients.

There were 15 hips without cage support and 25 hips with cage reconstruction. Patient demographics and preoperative hip scores were comparable in each group. After 4 years of follow-up we have evaluated 26.3% aseptic loosening in impaction grafting alone, and 8.3% loosening in impaction with cage reconstruction. We have concluded that the metal cage allows for a better stability, protects the cancellous graft micromotion and eventually leading to a better incorporation in segmentary defects. Impaction of the cancellous bone cubes without a cage support in segmentary acetabular defects may prone to fail because of the micromotion between the cement and the graft which is not contained in stable walls.