Accuracy of planar anteversion measurements using anteroposterior radiographs

Abstract

BackgroundSeveral methods using simple anteroposterior (AP) radiographs have been suggested for the measurement of anteversion of the cup component after total hip arthroplasty. Herein, we compared six widely used anteversion measurement methods using two different types of AP radiograph, the conventional pelvis AP and hip-centered AP radiographs, to identify the measurement method and the type of radiograph that would provide the highest accuracy and reliability.MethodsWe developed two custom-made bi-planar anteversion measurement models for the validation test. The models were designed for pelvis AP and hip-centered AP radiographs, respectively. The radiographs were acquired using the inclination angles of both models, changing from 10° to 70° at 10° increments. For each inclination angle, anteversion was changed from 0° to 30° at 5° increments. The measurements were obtained independently by two orthopedic surgeons blinded from each other’s measurements, using the methods of 1) Pradhan et al., 2) Lewinnek et al., 3) Widmer et al., 4) Liaw et al., 5) Hassan et al., and 6) Ackland et al. The measurements were repeated after 2 months. The accuracy, compared with that of the reference angle, and intra-observer and inter-observer reliabilities of each method were calculated.ResultsThe highest accuracy was found when the method of Liaw et al. was used with hip-centered AP radiographs, which showed a difference of 1.37° ± 1.73 from the reference angle. Moreover, regardless of the type of radiograph, the methods by Pradhan et al., Lewinnek et al., and Liaw et al. showed excellent correlations with the reference anteversion. However, substantial differences were found when the methods by Widmer et al., Hassan et al., and Ackland et al. were used, regardless of the type of radiograph used. When anteversion was measured in an inclination between 30° and 50°, the method of Pradhan et al., when used with pelvis AP radiographs, showed the highest accuracy (1.23° ± 0.92°). We also found no significant difference in anteversions between the measurements made on pelvic and hip-centered AP radiographs. Both interobserver and intraobserver reliabilities were high for all the measurements tested.ConclusionsThe methods by Pradhan et al., Liaw et al., and Lewinnek et al. may provide relatively accurate anteversion measurements with high reliability, regardless of the type of radiograph.

How to analyze postoperative radiographs after total hip replacement

“…On the other hand, AI over 45° reduces adduction and rotation. There is also higher wear of acetabular polyethylene when the AI is over 45° [ 13 , 14 ]. It cannot be univocally stated, without additional studies, what is a safe range for AI [ 15 , 16 ].…”

“…Because of that, plain radiographs are in common use. Plenty of methods can be used to measure anteversion, and there is no validated and most efficient one [ 14 ]. This is due to the fact that pelvic tilt has a greater impact on measuring anteversion on anteroposterior radiographs rather than determining abduction angle on anteroposterior radiographs.…”

Improving Acetabular Component Positioning in Supine Direct Anterior Total Hip Arthroplasty with a Transparency Template: A Novel, Simple, and Cost-effective Technique

“…Therefore, it can be hypothesized that there could be up to six degrees of difference depending on how the X-ray is acquired. The authors have chosen to use Lewinnek's method of anteversion measurement as studies have shown high inter- and intra-observer reliabilities and no significant differences in anteversion between measurements made on pelvis and hip-centered AP radiographs 28 29) . Lastly, there is a lack of clinical data at short- and long-term follow-up to determine if this accuracy in implant position translates to better clinical outcome in terms of reduced dislocation or revision rate.…”

Reliability and Validity of Standing Lateral Radiograph Method for Measuring Acetabular Component Version: A Modified Cross‐table Lateral Radiograph Method

“… 8 While computed tomography (CT) scanning accurately evaluates the component position and is regarded as the golden standard technique, 9 , 10 , 11 plain radiographs continue to be commonly used due to the relatively low cost and radiation exposure. 12 , 13 , 14 Anteroposterior (AP) pelvic radiography is the standard method used for inclination angle measurement. 15 The component version was generally measured using AP radiographs 12 , 16 , 17 or cross‐table lateral (CL) radiographs.…”

“… 12 , 13 , 14 Anteroposterior (AP) pelvic radiography is the standard method used for inclination angle measurement. 15 The component version was generally measured using AP radiographs 12 , 16 , 17 or cross‐table lateral (CL) radiographs. 18 , 19 However, the optimal plain radiographic method for cup version measurement is not preferred.…”