Acetabular Revision with Armature, Allografts and Cemented Prosthesis

ACETABULAR REVISION WITH ARMATURE, ALLOGRAFTS AND CEMENTED PROSTHESIS

M. Kerboull

This technique of acetabular reconstruction in failed total hips was developed 30 years ago in 1974. Since then, it has efficiently stood the test of time, even in the most severe cases of bone loss. Its goal is to reconstruct a bony cavity of normal size in anatomic position into which a standard acetabular component is cemented. Bone reconstruction is composed of fragments of a frozen femoral head: a bulky piece carefully shaped to repair the damaged roof; slices to reconstruct or thicken medial, anterior and posterior walls; morcellized cancellous bone to fill cavitary defects and gaps between structural grafts. This bony reconstruction is reinforced with a metallic cross-shaped armature which is fastened to the bone by its inferior hook and superior screws. This device which also acts as a guide for bone reconstruction, automatically provides the artificial hip with the right anatomical centre. It is stiff enough to secure a pelvic discontinuity, but because it is open, it remains flexible and does not change the elasticity of the acetabulum.

Wide and complex reconstructions can be carried out with this technique. On over 2000 cases operated on in the Orthopaedic Department of Cochin-Hospital Paris, and on 700 cases by myself, since 1974, we always managed to repair the acetabular bone defects even in type IV AAOS with a pelvic discontinuity. Postoperatively, within one year after surgery, grafts have united together and with the host bone. At 2 years, the progressive remodelling of the grafts is obvious in the superior as well as inner part, indicating that they are probably mechanically and biologically incorporated. At long term, there has been up to now no serious problem. In 57 cases there has been no resorption of the graft, no loosening of the socket. In 3 cases a resorption of the graft has been seen, twice due to osteolysis related to polyethylene wear, once to an immunologic problem on a patient who had developed antibodies against HLA of the graft.

The outcome of this type of acetabular reconstruction was published in the Clinical Orthopaedics and Related Research 4 years ago. On a series of 60 acetabular reconstructions with severe bone loss (AAOS type III for 48 hips and type IV for 12) operated on from 1976 to 1986 and reviewed with a mean follow up of 12 years (5 to 24 years), clinical results were satisfactory for 90 % of the patients. Ninety-five percent were radiologically successful; there were 3 failures (5 %) due to resorption of the graft and socket loosening. In any case, with a 92 % survival rate at 16 years (acetabular component loosening as end point) this technique seems valuable and reliable even at long term.