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Background: Clinical outcomes of total hip arthroplasty (THA) for Crowe type IV are poorer than for Crowe type I, because it is more difficult to accurately position the acetabular components. This study aimed to examine the accuracy of the computed tomography (CT)-based navigation system for acetabular component positioning in primary THA for Crowe type IV., Methods: From 2006 to 2018, 29 patients who underwent 34 primary THAs for Crowe type IV were enrolled in the "Type IV" group and 32 patients who underwent 34 THAs for Crowe type I were enrolled in the "Type I" group, formed by matching patients in the Type IV group on age, gender, body mass index, and surgical approach. We investigated (1) the accuracy of the cup size between that at preoperative planning and that actually implanted and (2) the mean deviation of the cup angle and 3-dimensional position of acetabular components between preoperative plan and postoperative records., Results: The accuracy of the cup size was 79.4% and 94.1% in the Type IV and Type I groups, respectively, without a statistically significant change detected (P = .075). The mean deviations of the cup angle and 3-dimensional position were comparable in both groups., Conclusion: Using the CT-based navigation system, it was possible to accurately implant the acetabular component for Crowe type IV, and the accuracy was comparable to that for Crowe type I. The CT-based navigation system is a useful intraoperative tool to accurately implant the acetabular component, especially with severe pelvic deformities such as Crowe type IV., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Introduction: The influence of stem sagittal alignment on clinical outcomes is unclear in total hip arthroplasty (THA). The purpose of this study is to assess the relationship between stem sagittal alignment and clinical and radiographic outcomes using 3D-CT., Materials and Methods: We performed 370 consecutive primary THAs between 2009 and 2013. After exclusion, 102 hips in 89 patients using single tapered-wedge stem were included. Mean follow-up was 4.7 years. Stem sagittal alignment was measured using CT, and patients were divided into flexion and neutral alignment groups. Clinical and radiographic outcomes were compared between two groups. Furthermore, we evaluated the anterior femoral offset and initial contact state., Results: There were no significant differences in clinical or radiographic outcomes between two groups. CT data analysis and multiple regression analysis showed flexion alignment increased anterior femoral offset (AFO) and Gruen zone 4 contact area., Conclusions: There was no significant difference in clinical or radiographic outcomes between flexion and neutral alignment of the tapered-wedge stem at an average of 4.7 years of follow-up. The increase of AFO and distal contact area in flexion alignment could affect the improvement of impingement-free range of flexion and intraoperative fracture.

Purpose: A computed tomography (CT)-based hip navigation system is a useful tool for achieving precise implant alignment angle. However, it has the disadvantage of prolonged procedure duration. A prolonged procedure duration may increase the incidence of postoperative surgical site infection (SSI) or periprosthetic joint infection (PJI) following primary THA. Studies identifying whether CT-based hip navigation system increases the incidence of SSI and PJI compared to the free-hand technique for total hip arthroplasty (THA) are rare. The study aimed to assess whether the CT-based hip navigation system can cause SSI and PJI compared to the free-hand technique. Methods: We investigated 366 patients with osteoarthritis who completed the minimum 2-year follow-up and underwent primary THAs (n = 435), including 70 hips in 62 patients of the non-navigation group and 365 hips in 304 patients of the navigation group. We compared the incidence rate of SSI and PJI between the non-navigation group and navigation group. Results: Only three patients in the navigation group (0.8%) developed SSI or PJI, while no patient developed SSI or PJI in the non-navigation group. There was no significant difference in the incidence rate of SSI or PJI between the two groups (P = 1.0), although the mean operation time in the navigation group was about 20 min longer. Conclusions: CT-based hip navigation system may not be associated with SSI or PJI after primary THA, although it prolongs the operation time. [ABSTRACT FROM AUTHOR]