Bone reconstruction, leg length discrepancy, and dislocation rate in 52 Wagner revision total hip arthroplasties at 44-month (mean) follow-up

Purpose of the study The primary and secondary stability of a revision impl ant is highly compromised in cases with important loss of bone stock from t he proximal femoral after severe femoral loosening. Several methods using i mplants with or without cement have been proposed for reconstruction after femoral bone loss. The purpose of this study was to analyze mid-term clinic al and radiological outcome with the Wagner prosthesis for revision surgery . Material and methods Fifty-two cases of aseptic femoral loosening were trea ted with this method in 36 women and 14 men, mean age 70 years (range 32-92 years). None of the patients was lost to follow-up; five who died after 18 months were retained for analysis. Mean follow-up was 44 months (range 18- 88 months). The mean preoperative Postel Merle d'Aubigne (PMA) score was 10 .5 +/- 0.4. These patients had major bone loss (5 grade II, 24 grade III, 2 3 grade IV in the SOFCOT classification). The transfemoral access was used in 17 cases and bone grafts in 32. Clinical outcome was assessed with the P MA score and leg length discrepancy was measured. Radiographically, stabili ty was assessed by measuring stem impaction and progression of radiolucent lines. Results The overall functional score was significantly improved from 10.5 /- 0.4 preoperatively to 14.6 +/-. 0.5 (p < 0.001). All items on the score improved but pain relief was the most notable. Improvement in the gait scor e was limited due to persistent limping in 39 patients. Leg length discrepa ncies were found in 8 patients with 6 shortenings and 2 lengthenings. The c linical situation remained stable after one year. The implant remained stab le in 48 patients (92 p. 100) and stem impaction was observed in 4 before 1 2 months. Two of these cases required a second revision. Metaphyseal recons truction was observed in 42 patients (81 p. 100), including 24 (46 p. 100) who exhibited homogeneous reconstruction with trabeculation. The reconstruc tion did not progress further after 18 months postoperatively. Complication s included four dislocations and five revision procedures (three for cup lo osening, two for femoral pivot instability). Discussion The functional outcome was similar to results reported in the li terature, including the high frequency of limping that was caused by variou s factors (valgus prosthesis neck, leg length discrepancy, muscle deficits) . Leg length discrepancies resulted from defective positioning or impaction at loading. Standard radiographic series allowed an assessment of stem imp action. Our low rate could be due to delayed weight bearing. La reconstruct ion of bone loss did not progress after 18 months and was independent of bo ne grafting, route of access, and the initial degree of loosening. The high frequency of dislocations with this type of implant can be prevented by ho rizontalization of the acetabulum and use of anti-dislocation inserts at th e first intention revision. Conclusion Our results with the Wagner prosthesis are satisfactory both cli nically and radiographically. The two drawbacks of this implant (limping an d dislocation), partly due to the design of the femoral stem, have led us t o study a new implant that preserves good distal anchoring and optimizes th e proximal biomechanics of the hip joint.