Measurement of pelvic tilt and rotation on AP radiographs using HipRecon: Validation and comparison to other parameters

Abstract

In this paper, we present and evaluate HipRecon, a noncommercial software package that simultaneously calculates pelvic tilt and rotation from an anteroposterior pelvis radiograph. We asked: What is the (1) accuracy and precision, (2) robustness, and (3) intra‐/interobserver reliability/reproducibility of HipRecon to analyze both pelvic tilt and rotation on conventional AP pelvis radiographs? (4) How does the prediction of pelvic tilt on AP pelvis radiographs using HipRecon compare to established measurement methods? We compared the actual pelvic tilt of 20 adult human cadaveric pelvises with the calculated pelvic orientation based on an AP pelvis radiograph using HipRecon software. The pelvises were mounted on a radiolucent fixture and a total of 380 AP pelvis radiographs with different configurations were acquired. In addition, we investigated the correlation between actual tilt and the tilt calculated using HipRecon and seven other established measurement methods. The calculated software accuracy was 0.2 ± 2.0° (−3.6–4.1) for pelvic tilt and 0.0 ± 1.2° (−2.2–2.3, p = 0.39) for pelvic rotation. The Bland–Altman analysis showed values that were evenly and randomly spread in both directions. HipRecon showed excellent consistency for the measurement of pelvic tilt and rotation (intraobserver intraclass‐correlation coefficient [ICC]: 0.99 [95% CI: 0.99–0.99] and interobserver ICC 0.99 [95% CI: 0.99–0.99]). Of all eight analyzed methods, the highest correlation coefficient was found for HipRecon (r = 0.98, p < 0.001). In the future, HipRecon could be used to detect changes in patient‐specific pelvic orientation, helping to improve clinical understanding and decision‐making in pathologies of the hip.

Pelvic tilt after Bernese periacetabular osteotomy—a long-term follow-up study

“…All other authors who investigated the change in pelvic tilt after acetabular reorientation osteotomy used either the sacro-femoral-pubic angle [ 21 ] or the pubic symphysis to sacroiliac index [ 10 ]. These two measurement methods showed a lower correlation with actual pelvic tilt compared with HipRecon [ 13 ].…”

“…This was an institutional review board–approved, single-center, retrospective, longitudinal controlled study conducted at a tertiary center for joint preservation surgery. We analyzed preoperative, postoperative and long-term follow-up AP pelvis radiographs using the previously validated software program HipRecon [ 13 ]. The analysis included a comparison of preoperative pelvic tilt with an asymptomatic control group as well as measurement of pelvic tilt immediately following PAO and during long-term follow-up.…”

“…HipRecon is a software that has been previously validated [ 13 ] and uses a statistical shaped model based on a 2D to 3D deformation–reconstruction method to create a patient-specific 3D model based solely on an AP pelvis radiograph ( Fig. 3 ).…”

“…In addition, studies mainly use 2D measurement methods on anteroposterior (AP) pelvis radiographs [ 10–12 ]. To the best of our knowledge, this is the first study to analyze the long-term evolution of pelvic tilt following PAO using a novel, previously validated 2D–3D deformation–reconstruction software for improved analysis of the 3D pelvic orientation [ 13 ].…”

Influence of acetabular and femoral morphology on pelvic tilt

“…The APP was identified, and APP-PT calculated, for all supine AP pelvic radiographs using the previously validated HipRecon software. 17,18 This non-commercial software is based on a 2D/3D deformation reconstruction algorithm using statistical shape modelling. Based solely on a standard AP pelvic radiograph (Figure 4a), pixel size, and film focus distance, HipRecon allows the creation of a patient-specific, virtual 3D model of the pelvis (Figure 4b).…”