Navigation of computer-assisted designed hip arthroplasty

Abstract

Acetabular and stem component mal-position during hip arthroplasty increase the risk of dislocation, reduce range of motion and may cause long-term wear. Computer assisted preoperative planning for total hip arthroplasty is used in our institution since 1990 on the basis of computer- assisted designed custom femoral stem [1]. Due to the recent developments in computer intra-operative assistance, the logical evolution was to obtain three dimensional data for intra-operative cup positioning during total hip arthroplasty (THA). After the initial work of DiGioia [2], numbers of computer-assisted orthopaedic systems have been described based on CT-based navigation or on imageless navigation. CT-based navigation need an intra-operative matching witch increases blood loss and time for surgery [3]. Among the imageless systems, one is based on Bone Morphing® technology initially described by Stindel [4] for computer assisted knee arthroplasty and adapted for THA. The principle is based on plastic intra-operative modeling of a statistical model. Thus anterior pelvic plane is registered intra-operatively by percutaneous palpation and cup impactor navigated in order to reach Lewinnek goals for cup abduction and anteversion angles. These types of imageless system do not require any extra radiation exposure for patients, or any loss of time for intra-operative matching with pre-operative planning. However, the benefits of an imageless system based on Bone Morphing® technology over freehand techniques for cup positioning should be proven. The purpose of this study was to present the concept and evaluate the performance of dedicated software for cup positioning combined to the computer-assisted preoperative planning routinely used in our institution for total hip arthroplasty in a prospective and randomized controlled study. © 2007 Springer Medizin Verlag Heidelberg.