title: CT outperforms radiography for determination of acetabular cup version after THA.
abstract: Precise evaluation of acetabular cup version is necessary for patients with recurrent hip dislocation after THA. We retrospectively studied 42 patients, who underwent THAs, with multiple cross-table lateral radiographs and CT scans to determine whether radiographic or CT measurement of acetabular component version is more accurate. One observer measured cup version on all radiographs. CT scans were interpreted by one observer. Twenty radiographs were measured twice each by two observers to determine intraobserver and interobserver reliability. We implanted cups in four model pelvises using navigation and compared measurements of anteversion made with radiographs and CT scans. Intraclass correlation coefficients (ICC) for anteversion measurements of two observers were 0.9990 and 0.9998, respectively, when comparing measurements of identical radiographs (intraobserver). Paired values for two observers measuring the same radiograph had an ICC of 0.9686 (interobserver) compared with 0.7412 for measurements from serial radiographs of the same component. The ICC comparing radiographic versus CT-based measurements was 0.6981. CT measurements had stronger correlations with navigated values than radiographic measurements. Accuracy of anteversion measurements on cross-table radiographs depends on radiographic technique and patient positioning whereas properly performed CT measurements are independent of patient position.
authors.affiliation: Department of Radiology, Hospital for Special Surgery, New York, NY 10021, USA.
authors.forename: Bernard
authors.initials: B
authors.lastname: Ghelman
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Kepler
authors.forename: Stephen
authors.initials: S
authors.lastname: Lyman
authors.forename: Alejandro González
authors.initials: AG
authors.lastname: Della Valle
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000209:etiology; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D015588:Observer Variation; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*