Comparison of Endofemoral and Transfemoral Approach in Revision THA Using a Straight Cementless Ti6A17Nb Grid Blasted Stem Design with Grooves and Ridges

Introduction: The purpose of this study was to determine the clinical and radiographic resuJLs of the cementless Wagner SL revision stem comparing transfemoral approaches with endofemoral approaches. Materials and Mcthods: According to a prospective study protocol ali patients who received consecutively a cementless Ti6A17Nb grid blasted Wagner SL Revision Stem (Protek AG, Bem, Switzerland) for revision total hip reconstrucùon between May 1989 and May 1996 were reviewed. Of the 64 patients with 64 implantations (45 men and 19 women, mean age 67.2 years) 7 patients died for imrelated reasons and 3 patients were not traced anymore. The reason for revision was mechanicaJ failure (aseptic loosening, femoral firacture and femoral component fractuie) in 58 patients and septic loosening in 6 patients. There were 47 first revisions, 13 second revisions and 4 third revisions. Femoral deficiencies were classified according to Paprosky et al. (1990). In 50 patients a posterior approach without trochanteric osteotomy was used. In the remaining patients a transgluteal approach according to Bauer (1990) was used. For the retrieval of the previous component and cement a transfemoral approach with coitical fenestratton was used in 22 patients (Wagner 1989) and an endofemoral approach without fenestration in 42 patients. Resuits: So far no rerevision operadons were necessary. There was no significant dijjerence when the mean blood loss for the two techniques was compared (685ml± 372 versus 703ml ± 386). The mean operating time was significantly shorter with the transfemoral approach (lOSmin vs. 136min). As intraoperative complications in 7.8% femoral stem firactures (mainly in the region of the diaphyseal antecurvation, ali in endofemoral approaches) were encountered. Ali of these fractures healed using long stem components and cerclage wiring. Clinical deep-vein thrombosis occurred in 4.7%. In the radiographic analysis a temporary subsidence of the femoral component without progressive loosening was found in 7.8%. In 18.8% radiolucencies up to Imm in one to three zones was foimd. Bone stock quality improved independent of i additional allografting in cavitary defects but in a lesser degree in segmentai defects. The distribution for The mean i Harris Hip score was preoperatively 57 (25-84) and postoperaùvely 86 (53-100). There was no difference when the transfemoral approach was compared with the endofemoral approach. i ' Discussion: Early resuits on the efficacy of pro>cimally porous coated stems were encouraging (Gustilo 1989). Midterm resuits however were showing rather high subsidence rates (Trousdale 1994) that were increasingly attributed to poor proximal bone quality in revision cases which is inadequate for a proximally porous coated implants that rely on press-fit I G.xation in the metaphyseal area for initial prosthetic stability. In this study a grid blasted stem with sharp ridges that '•• allows diaphyseal fi.xation was used. So fart the resuits up to 7 years are encoiu^ging. However, the straight stem design I has its limit in the antecurvation of the femur This is probably the main reason for the occurrence of diaphyseal fractiu-es ; in this study. To solve this problem in such rare cases an anatomically shaped component is mandatoiy. In this study the transfemoral technique with cortical fenestration abbreviated operating time considerably. The success of bone grafting in femoral revision surgery depended on defect size and defect type. Conclusion: The mid-term clinical and radiographic resuits of the cementless Ti6AI7Nb grid blasted Wagner SL Revision Stem are encouraging. The transfemoral approach appeared to have advantages in respect to intraoperative complications and operatine time.