Despite improvements in prosthesis design, the clinical outcome of total hip arthroplasty still has 10% failure rate after 10 years. Component malpositioning can lead to instability, impingement, excessive wear and loosening. Computer-assisted procedures are expected to improve the accuracy of component positioning, and therefore the long-term outcome. We present an original hip navigation system that allows controlling leg lengthening, offset and stability without the use of the pelvic anterior plane. Because the reliability of the pelvic anterior plane (Lewinnek plane) remains discussed, we present a computer-assisted hip replacement using a functional femoral reference plane. Direction and depth of the acetabular reaming and progression of the femoral rasp are calculated by a sophisticated algorithm, as well as the components' final position, in order to control leg lengthening and offset. In addition, the ROM to impingement (and therefore the stability) is continuously displayed relative to the position of the components. Simple graphical and numerical data in addition to virtual instruments displayed on the screen aid the surgeon during the entire procedure.Introduction
Material and Methods
