Comparison of navigation accuracy in THA between the mini-anterior and -posterior approaches

Background The accuracy of a CT-based hip navigation might depend on surgical approaches, resulting in varying accuracy of implant alignment. Methods We performed primary cementless total hip arthroplasty (THA) with mini-incision surgery (MIS) to 40 well-matched patients (anterior or posterior approaches, 20 hips each), using navigation with surface registration. We investigated cup alignment using postoperative computed tomography (CT) and compared the navigation accuracy between the two approaches, i.e. the difference between intra-operative and postoperative alignments of the cup. Results There was no significant difference between the two approaches. The mean navigation accuracies in abduction and anteversion were 2.0 degrees (SD 1.4 degrees) and 2.7 degrees (SD 1.9 degrees), respectively, in the anterior approach, and 2.4 degrees (SD 2.0 degrees) and 2.0 degrees (SD 1.4 degrees), respectively, in the posterior approach. All cup alignments were within 100 of the target orientation. Conclusions This CT-based navigation for MIS-THA provides navigation accuracy without significant differences between the two approaches and with favourable alignment of the cup. Copyright (C) 2008 John Wiley & Sons, Ltd.