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 crosstable radiographs depends on radiographic technique and patient positioning whereas properly performed CT measurements are independent of patient position.

Use of Morphometry to Quantify Osteolysis after Total Hip Arthroplasty

“…Values of 0.75 to 0.90 have been described as ''good to excellent reliability'' [36], but elsewhere it is suggested the value should be 0.90 or more for clinical use [38]. Our ICCs were all 0.90 or greater for a range of observers which indicates high reliability and is comparable with other orthopaedic radiologic studies [13,14]. This is an acceptable level of agreement for use of the measurement obtained as one part of the decision-making process for a patient when recommending invasive treatment such as revision surgery.…”

The John Charnley Award: Risk Factors for Cup Malpositioning: Quality Improvement Through a Joint Registry at a Tertiary Hospital

“…First is the use of a computer software program to obtain inclination and version angles without accounting for pelvic tilt, which could influence the calculated angles. Recent studies show CT scans measure acetabular version more accurately than radiographs [15] and the combination of CT scans and radiographic information is the most effective tool to accurately measure cup position [31,43,51,57]. Second, we did not measure the rotational position of the femoral stem in the femoral canal.…”

Failed Metal-on-Metal Hip Arthroplasties: A Spectrum of Clinical Presentations and Operative Findings

“…The results of any hip aspirations were recorded if available. Preoperative anteroposterior and cross-table lateral hip radiographs were retrospectively analyzed in blinded fashion by a single reviewer using digital templating software to determine acetabular component abduction and anteversion angles, respectively; plain radiographs have been reported to give good, but not excellent, reproducibility and acceptable interobserver reliability for radiographic measurement of cup position but are less exact than CT measurement [8]. Additional imaging studies (CT or MRI) were not routinely obtained, although they were reviewed for this study if they had been performed.…”