[Personal experience with the Wagner revision stem in hip joint reoperations].

PURPOSE OF THE STUDY: Since 1993 we have been using the Wagner revision stem, initially in the length of 265 mm and 305 mm and later also the short stem of 190 mm and 225 mm, for revision surgery with the destruction of proximal femur. This technique provided for primary fixation of the stem in the unaffected femoral bone and creates prerequisites for the bone regeneration and bone formation of the destructed host bone by the loosened implant in the metaphysis and proximal part of diaphysis.

MATERIAL AND METHODS: In the period of 1993-1998 we operated on and followed a group of 35 patients (18 men and 17 women), average age 69 years (age range, 52-89). In 32 patients we performed revision surgery of Poldi-Cech stem, twice CF-30 stem and once cementless J + J stem. The average time interval between the primary operation and revision surgery was 10 years (range, 2-22 years). Thirty patients had to be reoperated due to aseptic loosening of the implant and five patients due to infection. Wagner stem was applied no sooner than 6 months after the infect had healed. In the application of the short stem (190 mm or 220 mm) we use Bauer approach (4 times) or extended Bauer approach (4 times), in long stems we use transfemoral approach in our modification: osteotomy is performed from the extended Bauer approach in the frontal plane and the anterior part of femoral cortex is retracted. The retracted anterior part of the femoral cortex femoral bone is fixed back only by hemi-wire loops.

RESULTS: Of the total number of 35 operated on 2 patients required revision surgery due to the subsidence of the stem and one removal of the stem in case of complete protrusion of the cup into pelvis. In short stems there were no post-operative complications. Dislocation of the hip occurred in three patients after the implantation of the long stem. After the closed reduction the surgery was not necessary. In one patient there developed an infection 5 months after operation. It was a hematogenous infect resulting from a pyogenic affection of the operated on limb. A two-step revision surgery was performed with a spacer and a subsequent reimplantation of a stem of greater diameter.

DISCUSSION: Wagner presents results of 69 patients after the application of his own stem 265 mm and 305 mm long. In 62 patients of the total number no subsidence was encountered, in two cases post-operative dislocation was recorded. Isakson et al. do not consider subsidence resulting in fixation of the stem as a significant factor and correct the difference in the length by shoes. They point out that this method is suitable for the solution of defects of proximal femur in such a way that the implant has a stable fixation and provides for bone formation, restoration of the destructed part of proximal femur in the extent of the original loosened stem. We consider the Wagner technique a significant contribution to the solution of these severe complications. As compared to Wagner, instead of the sagittal plane we perform transfemoral approach in the frontal--horizontal plane which allows operation in the supine position of the patient and a more precise replacement of the cup. In our group of patients we incorrectly used the long stem without transfemoral approach in 3 patients, one patient required revision surgery, in the remaining two patients the period of osteointegration of the stem was substantially longer.

CONCLUSION: The Wagner revision stem allows treatment of the destructed proximal part of femur caused by loosening of the stem and polyethylene granuloma. Of great importance is the preservation of the contact of muscles and residual parts of the destructed femoral bone. The short version of the Wagner stem (190 mm and 225 mm) has fully justified itself in revision surgeries of the replacement of the stem in cases of a preserved bone stock. Wagner stem sufficiently bridges the trepanation hole and is safely engaged in the femoral shaft. The long Wagner stem (265 mm and 305 mm) has proved suitable in revision surgeries in cases of thinner cortex and defects in the whole length of the loosened implant. This stem requires a transfemoral approach and a perfect stable anchoring of the stem in the stable skeleton of the femoral shaft. Bone formation and remodelling of proximal femur does not affect the length of the limb. Of great importance is its accurate planning. This procedure is a considerable contribution to the solution of these severe complications.