Ultra-Short Stems with Proximal Load Transfer: Clinical and Radiographic Results at Five-Year Follow-Up

Abstract

Bone stock preservation is crucial when performing THR in young patients. Following this philosophy, an original ultra-short custom-made implant with extensive proximal load transfer was developed. It presents three very innovative features: absence of the diaphyseal portion of the stem, a well defined lateral flare with load transfer on the lateral column of the femur and a very high femoral neck cut. These innovations resulted in a very conservative implant both of the bone stock and the soft tissues. In this study we reviewed the X-rays of 111 patients with 131 primary total hip replacements performed with this implant. The average pain score using the Harris Hip Score system, at an average of five years after surgery, was 42 of 44 points; 95 per cent (124) of the patients had no or slight pain. We had no cases of thigh pain. None of the patients required a femoral stem revision. Two cases had to be re-operated for polyethylene liner exchange but the femoral implant was stable and left in place. At five years, all implants appeared radiographically stable with well maintained proximal bone stock. It was concluded that the geometry of this implant provides significant initial stability, which seems to be preserved throughout a long follow-up period. This study validates the assumption that torsional loads can be controlled even without the diaphyseal portion of the stem and that neck preservation combined with lateral flare support guarantees a more natural loading of the femur.