Adaptive bone remodeling around cementless femoral stems with two different designs: fitmore and Alloclassic

Abstract

Introduction. We hypothesized that a short stem preserves periprosthetic bone mass in the proximal femur after total hip arthroplasty (THA). We performed a comparative analysis of clinical efficiency and X-ray results of the BMD around two cementless femoral stems with two different designs. Purpose. To compare the clinical and radiographic results of the study of adaptive bone remodeling in the proximal femur in patients after implantation of the femoral component and Alloclassic Fitmore Material and methods. We evaluated two groups of patients (mean age 58,3): 26 patients with a short femoral stem Fitmore (Zimmer) and 20 patients with a standard stem Alloclassic (Zimmer). Clinical assessment of the hip condition was made according to Harris scale, supplemented by the evaluation of the pain level for femur by a visual analog scale at three levels. The radiological result was studied according to radiogrammetry and dual-energy X-ray absorptiometry (DXA). Results. Independently from design of the femoral component in both groups of patients was observed a significant clinical improvement. The BMD on the surgery side was measured using of analysis in Gruen zones. The first postoperative measurement was performed after surgery and further in 3, 6 and 12 months. DXA after 3 mo showed progressive loss BMD in all Gruen zones, but more significant in Gruen zones 2, 7 for Fitmore stem group, in Gruen zones 6, 7 for Alloclasic stem group. At 6 mo after THA in all Gruen zones of Fitmore vs Alloclasic femoral stems there were the phase of moderate stabilization. At 12 mo we observed decreased periprosthetic BMD in Gruen zone 1 and 7, however that there are no clinically relevant changes around two different designs of cementless femoral stems. Discussion. It isn’t dependent on design of a metal stem we showed progressive remodeling periprosthetic BMD in the proximal parts of hip (Gruen zone 1, 7) and we observed а slighter hypertrophy in the distal parts of femoral stem (stress-shielding). We conclude that using short stems have not benefit in preservation bone of proximal femur.