Reproducing the proximal femur anatomy using neck anchorage stem design

Abstract

Neck-sparing stem designs enable a personalised (patient-specific) surgery by reproducing the native proximal femur anatomy. This facilitates physiological soft-tissue tension and hip kinematics, hopefully responsible for higher prosthetic hip function and patient satisfaction, as well as reduced risk of dislocation. Moreover, the bone economy achieved by this implant design is an obvious advantage in terms of easing revision surgery and decreasing stress-shielding-induced bone loss. The authors present their experience of using a neck-only tapered prosthesis with hydroxyapatite (HA) and porous coating: the Silent™ Hip system. The concept of the silent hip (Fig. 5.1) was first considered by Dr. Allan Ritchie in the mid-1990s when the need for a better solution for younger, more active and demanding patients was first recognised. Following this, a group of engineers and surgeons took this concept to development in conjunction with the University of Hamburg [1]. The implant went on to satisfy pre-clinical in vitro evaluation, and in 2003, the clinical study began to assess the stability of the implant, using two surgeons (Dr. Honl and Sullivan) to assist DePuy with the findings. Between January and November of 2003, 41 implantations were performed. Following this, a wider study began to test the validity of the technique with a wider range of surgeons, with encouraging results.