EVALUATION OF PERIPROSTHETIC BONE RESORPTION SECONDARY TO FIRST TOTAL HIP REPLACEMENT WITH METHA® SHORT HIP STEM: FOLLOW-UP EXAMINATION RESULTS AT 48 MONTHS

Purpose: The aim of this study is to evaluate the e ects of the BBraun Metha short hip stem with femoral neck metaphyseal anchoring at the level of the 7 Gruen zones and to de ne the evolu on of periprosthe c bone resorp on associated to this type of stem. Methods: 20 pa ents with average age of 59, were selected in this study in accordance with speci c inclusion and exclusion criteria. Clinical examina- on (Harris Hip Score and Womac Score), radiological evalua on (AP and LL X-ray views) and DXA scan (7 Gruen zones) were performed on each pa ent following a speci c protocol: T0 (within six months from surgery), T12, T24, T36 and T48. Results: Harris Hip Score (HHS) and Womac Score signi cantly improved. All radiological follow-up examina ons did not show evidence of radiolucency. 2 cases of calci ca ons were found on x-ray examina ons, but were not clini- cally relevant. No stem was surgically revised. No episodes of joint disloca- on or infec ons occurred. The densitometry evalua on a er 48 months con rm that the periprosthe c BMD evolu on had a posi ve outcome in every Gruen zones, with the excep on of the calcar region (R7), avoiding the proximal metaphyseal region that over the me could damage the stability and the longevity of the stem itself. There is also evidence of periprosthe c bone density changes, mainly star ng from 24 months a er surgery. Sta s - cally signi cant results (Wilcoxon signed-ranks test, P<0.05) were document- ed at the level of R5 and R6 regions at 24, 36 and 48 months. Conclusions: The Metha® stem is able to reduce the proximal periprosthe c bone resorp on, thanks to its femoral neck metaphyseal anchoring, and to provide a greater longevity of the stem itself. From the comparison between our data and the literature data bone remodelling around the Metha stem appears to be also related to level of the osteotomy and to the stem angu-la on (varus and valgus), showing a variability of the operator dependent results. According to our study, we can conclude that the follow-up evalua- on of the Metha® BBraun hip stem at 48 months, had a posi ve outcome on the periprosthe c bone resorp on especially at the level of the proximal regions, although the DXA scan results could be in uenced by the di erent angula on of the operator dependent stem.