HIP REPLACEMENT WITH SPECIAL MODULAR ZMR STEM: FIRST EXPERIENCES

Abstract

Different revision stems are described in literature: from the primary systems, with or without cementation, used for minor defects of the proximal femoral region, to special revision stems employs in order to by-pass meta-epiphyseal zones with high loss of bone-stock and to search a distal fit.

The Authors describe their experience with modular system ZMR (Zimmer, Warsaw, IN, USA), in Titanium alloy, available in two “configurations”: porous, in three distinct porous body styles with variable inclination neck to pair with straight or porous bowed spline stems available in different lengths and diameters optimising axial and rotational stability, and Taper, designed to provide a better distal fixation transmitting axial, torsional and bending loads to the adjacent bone through a splined taper stem, a more physiological cervical-diaphyseal angle and a neck planned in order to save the calcar zone. The mid-stem junction uses a Morse-type taper connection with a dynamometric system to assure locking of the body and stem components.. The Authors underline the benefit to use a versatile system able to allow the intraoperatory choice of antiversion, diameter and length more adapted diminishing the risks of a post-operative sinking and avoiding the corrosion phenomena of splice sites.