Abstract
Purpose: Between 1979 and 2000, we performed 115 total hip arthroplasties with a bone block, mainly for degenerative hips secondary to congenital dislocation. Up to 1992, we used the classical bone block fixed with a screw and a cemented all-polyethylene Charnley cup inserted in the paleoacetabulum. The drawback of this technique was the two-month delay required for bone healing before weight bearing could be attempted. Since 1992, we have modified this technique, using an embedded bone block impacted into the dihedral angle between the capsule – neoacetabulum and the non-cemented press-fit cup with a screw in the paleoacetabulum. This method allowed immediate postoperative weight bearing, just like after first-intention total hip arthroplasty.
Material: Between 1992 and 2002, we operated 56 patients (63 hips) using this technique, 50 (56 hips) were reviewed at a mean five years (range 1 – 9.5). Three patients had died (three hips) and three (four hips) were lost to follow-up. The purpose of this work was to check integration of the bone block and absence of acetabular complications related to early weight bearing. Mean age at surgery was 58.5 years (range 17 – 88). There had been one earlier intervention for 17 hips, two for 13 and three for four.
Methods: Physical examination and standard x-rays (AP, lateral, Lequesne oblique views) were available at last follow-up. In addition to the radiographic assessment of the bone block, the Postel Merle d’Aubigné (PMA) objective clinical score and subjective patient satisfaction were recorded.
Results: The mean PMA score was 11.7 preoperatively and 17.6 at last follow-up. Ninety-four percent of the patients were very satisfied or satisfied, 6% were dis-satisfied (three postoperative dislocations). Radiographically, we noted block lysis (n=1), non-integrated block (n=8), perfect osteointegration (n=47). The cup showed no radiographic sign of ascension. There were two lucent lines in zone 1 (14.8%) and three in zone 3 (16.8%). There was no relation between bone block integration and presence of acetabular lucent lines. Four complications were recorded: one loosening at eight months, one sudden loosening treated by changing the cup, and three dislocations including one treated four years after implantation by anti-dislocation crescent. There was no relationship between complications and block behaviour.
Discussion: The advantage of the embedded block technique with a hybrid prosthesis using a metal-backed polyethylene cup (22.225) is that the postoperative rehabilitation is the same as after a standard prosthesis in good position. Immediate weight bearing on the press-fit cup without cement did not lead to deleterious complications whether clinically or for bone block behaviour.
Conclusion: This technique is a reliable method allowing early weight bearing and a shorter recovery time with satisfactory cup stability.
The abstracts were prepared by Docteur Jean Barthas. Correspondence should be addressed to him at Secrétariat de la Société S.O.F.C.O.T., 56 rue Boissonade, 75014 Paris.
