COMPUTER NAVIGATION ASSISTED TOTAL HIP REPLACEMENT PROVIDES PREDICTABLE AND REPRODUCIBLE RESULTS WITH ACCURATE COMPONENT PLACEMENT.

Abstract

Introduction: The long-term results of total hip replacement can be improved by accurate placement of the implants, leading to restoration of hip biomechanics and prevention impingement from of implant malposition. Pelvic obliquity from patient positioning during surgery prevents accurate intra-operative assessment of component placement. Computer navigation assisted total hip replacement can potentially eliminate these problems by providing feedback on prosthetic placement during surgery. The purpose of our study was to assess the accuracy of the component placement in computer navigation assisted THRs performed in our institution.

Methods: A total of 154 computer navigation assisted total hip arthroplasties performed between January 2004 and January 2005 were prospectively included in this study. Image free optical based navigation system (Navitrack™) was used. All procedures were performed by the senior author using MIS and open posterior approaches. Two independent observers performed analysis of the position of components and leg length discrepancy from standardized hip radiographs. Navigation values during surgery were compared with postoperative radiographic evaluation.

Results: The mean abduction and anteversion angles of acetabular component in postoperative radiographs were 41.4 ± 6.1 and 22.6 ± 3.8 degrees respectively, in comparison to the navigation values of 40.9 ± 4.0 and 22.9 ± 3.6 degrees respectively. The femoral neck offset and leg length discrepancy calculated from navigation were with in a mean of 1.5mm and 2.8mm, respectively. There was one complication consisting of a peri-prosthetic femoral fracture that was recognised during surgery and treated with revision of the femoral component to a long-stem prosthesis. There was no early post-operative dislocation or deep infection in this series.

Discussion: This study showed that computer navigation assisted THR provided predictable and reproducible results with accuracy in component placement and restorations of femoral neck offset and leg length.