14 YEARS’ FOLLOW-UP IN A SHORT HIP IMPLANT WITH LATERAL FLARE.

Abstract

The lastest biomechanical studies have shown that the load in the proximal femur is transferred not only medially but also laterally. Following these new philosophies, an original ultra-short stem with extensive proximal load transfer was developed. The main features of this implant are: an almost complete absence of the diaphyseal portion of the stem; a well defined lateral flare with load transfer also on the lateral column of the femur; and a high femoral neck cut which allows the preservation of most of the anterior, posterior and medial wall of the femoral neck (giving a complete proximal circumferencial bone in-growth). The implant, which we began to use in 1995 as a custom made prosthesis based on pre-operative CT data (140 cases), and later as a standard prosthesis (Proxima Hip 347 cases) was, in the first years, recommended only for young and active patients before being extended with very large indications also to elderly ones. Purpose of this paper is to present clinical and radiological results of 487 implants with an 7 yrs average follow-up. (14 yrs to 3 months). Harris Hip Score (HHS) formed the basis of the clinical assessment. Serial post-operative AP and lateral radiographs were taken for all patients.

Excellent results were reported: patients were followed-up for up to 14 years in all the series there were no revisions for aseptic loosening and only one case was revised for a deep infection. The mean HHS increased from 44.8 pre-operatively to 98.6 post-operatively at the latest follow-up. Tight pain was recorded only in one case. Other complications included 3 dislocations and 2 superficial wound infections. Radiographically good periprosthetic bone remodelling with increase of the bone stock around the implant. No radiolucent lines, subsidence or loosening have been observed.

In conclusion after a 14 year experience we can assert that neck preservation combined with a proximal lateral flare support guarantees a more natural loading of the femur and large indications. The absence of the stem makes this implant ideal not only for conventional surgical approach but also for MIS.