The Comparison of Paired Point Matching and Fluoroscopic Matching

Background The main factor of osteoarthritis (OA) of the hip in Japan is secondary due to developmental dislocation of the hip and hip dysplasia. For this reason, navigation is useful to treat complicated cases. Purpose We performed total hip arthroplasty (THA) for the secondary OA of the hip using paired point matching and fluoroscopic matching, and compared the accuracy between them. Materials and Methods We retrospectively reviewed 91 hips who underwent THA for the secondary OA of the hip. We measured the angle of the cup (anteversion and inclination) from intraoperative verification and postoperative computed tomography (CT), and calculated the difference. Then, we compared 71 hips in the paired point matching with 20 hips in the fluoroscopic matching. Results According to the Crowe classification, the cases consisted of 64 hips in Crowe1, 19 hips in Crowe2, and 8 hips in Crowe3. The differences of the degrees defined with the intraoperative verification and the postoperative CT were as follows: As for inclination difference, the paired point matching showed 3.9 mm (range, 0.1–11.4) while the fluoroscopic matching showed 3.7 mm (range, 0.9–9.7), which showed no significant difference (Fig. 1). As for anteversion, the paired point matching showed 5.2 mm (range, 0.2–23.5), whereas the fluoroscopic matching showed 2.7 mm (range, 0–8.2), thus the fluoroscopic matching was significantly accurate in anteversion. (Fig. 2). Conclusion Fluoroscopic matching provides greater accuracy than paired point matching in navigation THA.