CEMENTED FEMORAL REVISION WITH MORCELIZED ENDOSTEAL BONE ALLOGRAFTS PROTECTED BY A METALLIC MESH - RESULTS IN 19 HIPS AFTER 83 MONTHS FOLLOW-UP

Purpose of the study To assess after 83 months of follow-up, the resul ts of 19 femoral revisions carried out according to an original method combining a cemented stem and bone reconstruction by means of impacte d-morcelized bone allograft protected by a titanium mesh. Materials Tw enty hips (18 patients mean aged 58 at surgery) were included between 1986 and 1991, Five hips had a least one previous prosthetic revision, one hip was revised because of septic loosening. No patient was lost for follow-up, but two had died during the follow-up period: one patie nt died one month after surgery was excluded, one other died 7 years a fter the index procedure and was included with his last hip rating. Lo ss of femoral bone stock was severe according to the SOFCOT four stage rating system : 2 femurs were grade II, 14 grade III, and 3 grade IV. Femoral stem migration was assessed with landmarks recommended by Wal ker. All the measurements were performed with a digitizer (OrthoGraphi cs(TM)). Methods All the procedures were carried out through a postero lateral approach, augmented by 4 trochanteric osteotomies and 5 distal femoral windows. After prosthesis and cement removal, a bone plug was placed into the medullary canal. Then, cancelous bone morcelized allo grafts were impacted in the femoral defects through the medullary cana l, A titanium mesh cylinder was placed into the femur to separate the graft from the cement introduced later to obtain fixation of the revis ion stem. The stem was extended about 5 centimeters over the distal ed ge of the grafts in order to bridge the femoral defects. The mesh was extended only in front of the grafts and was used to protect them from excessive cement penetration. Results Functional improvement was noti ceable since the Merle d'Aubigne Hip score improved from 9.8 to 16,3 a t follow-up. The pain score improved from 2.1 to 5.5 and walking score from 2.3 to 5. Adverse effects occured during the first cases and wer e related to cement removal : 3 greater trochanter fractures, 5 distal femoral perforations and 2 non displaced femoral shaft fractures, The septic revision had recurrence of infection associated with radioluce nt lines > 2 millimeters and the only one graft resorption. One trocha nteric non-union was observed but no prosthetic dislocation. Only one femoral stem migration (4.4 millimeters) was detected without any othe r radiographic features of loosening after 9 years of follow-up, This stem was considered as loosed, but was not revised because of few clin ical symptoms. Only 2 radiolucent lines less than 2 millimeters at the bone cement interface in Gruen's zones 3 to 5. Likewise, no radiograp hic feature of stress-shielding was observed. On follow-up X-rays, 3 h ips had corticalisation of the grafts, and 12 hips demonstrated normal cancelous trabeculations in the grafts. Conclusion Satisfactory funct ional and radiographic results were obtained with this method after 5 to 10 years of follow-up instead of severe preoperative femoral bone s tock impairement. Likewise, we observed only one recurrence of looseni ng diagnosed with the help of digitized X-ray examination. Only one si gnificant (> 3.5 mm) femoral stem migration was detected. Radiographic features of femoral reconstruction were observed but without histolog ic proof of graft integration. This method uses a longer stem than the ''Exeter'', but avoids a high rate of femoral stem migration and appe ars compatible with femoral bone reconstruction.