Abstract
Introduction:
Acetabular component orientation has been linked to hip stability as well as bearing mechanics such as wear. Previous studies have demonstrated wide variations of cup placement in hip arthroplasty using conventional implantation techniques which rely upon either anatomic landmarks or the use of commercial positioning guides. Enabling technologies such as navigation have been used to improve precision and accuracy. Newer technologies such as robotic guidance have been postulated to further improve accuracy. The goal of our study was to evaluate the clinical reproducibility of a consecutive series of haptically guided THR.
Methods:
119 patients at 4 centers were enrolled. All patients had preoperative CT scans for the purpose of planning cup placement in lateral opening and version using proprietary software (Mako, Ft. Lauderdale, FL). All procedures were performed using a posterolateral approach. Following bone registration, acetabular preparation and component position is performed using haptic guidance. Final implant postion is ascertained by obtaining 5 points about the rim of the acetabular component and recorded. At 6 weeks, all patients had AP and cross-table lateral radiographs which were then analyzed for cup abduction and anteversion using the Hip Analysis Suite software. The goal was to determine the variability between desired preoperative plan, intraoperative measurement and postoperative results.
Results:
Of the 119 hips replaced, 9 hips were excluded due to problems using the Hip Suite software leaving 110 hips for analysis. As seen in Table 1., the mean cup inclination was planned for 40.0 degrees. Intraoperative recorded inclination was 39.9 degrees and using the Martell software, 40.4 degrees. Planned cup anteversion was 18.7 degrees, with intraoperative measurement of 18.6 degrees and postoperative Hip Suite analysis 21.5 degrees. There was no significant difference between any of these measurements.
Conclusion:
The use of a haptically guided robot to prepare and implant an acetabular component during total hip arthroplasty is both precise and accurate based upon this multicentered study. While further research determining optimal cup position is needed, these results suggest that the ability to achieve desired position is possible utilizing this enabling technology.
