Pelvic tilt from supine to standing in patients with symptomatic acetabular retroversion of the hip

Abstract

Aims Acetabular retroversion is a recognized cause of hip impingement and can be influenced by pelvic tilt (PT), which changes in different functional positions. Positional changes in PT have not previously been studied in patients with acetabular retroversion. Methods Supine and standing anteroposterior (AP) pelvic radiographs were retrospectively analyzed in 69 patients treated for symptomatic acetabular retroversion. Measurements were made for acetabular index (AI), lateral centre-edge angle (LCEA), crossover index, ischial spine sign, and posterior wall sign. The change in the angle of PT was measured both by the sacro-femoral-pubic (SFP) angle and the pubic symphysis to sacroiliac (PS-SI) index. Results In the supine position, the mean PT (by SFP) was 1.05° (SD 3.77°), which changed on standing to a PT of 8.64° (SD 5.34°). A significant increase in posterior PT from supine to standing of 7.59° (SD 4.5°; SFP angle) and 5.89° (SD 3.33°; PS-SI index) was calculated (p < 0.001). There was a good correlation in PT change between measurements using SFP angle and PS-SI index (0.901 in the preoperative group and 0.815 in the postoperative group). Signs of retroversion were significantly reduced in standing radiographs compared to supine: crossover index (0.16 (SD 0.16) vs 0.38 (SD 0.15); p < 0.001), crossover sign (19/28 hips vs 28/28 hips; p < 0.001), ischial spine sign (10/28 hips vs 26/28 hips; p < 0.001), and posterior wall sign (12/28 hips vs 24/28 hips; p < 0.001). Conclusion Posterior PT increased from supine to standing in patients with symptomatic acetabular retroversion. The features of acetabular retroversion were less evident on standing radiographs. The low PT angle in the supine position is a factor in the increased appearance of acetabular retroversion. Patients presenting with symptoms of hip impingement should be assessed by supine and standing pelvic radiographs to highlight signs of acetabular retroversion, and to assist with optimizing acetabular correction at the time of surgery. Cite this article: Bone Joint J 2022;104-B(7):786–791.

Acetabular retroversion: functional or anatomical?

“…The change in pelvic tilt from supine to standing demonstrated in this study is in keeping with previous research into the relationship of pelvic tilt with AR. A previous study from our institution reported a low pelvic tilt angle in the supine position which contributed to the appearances and symptoms of retroversion, 10 and a change in pelvic tilt from supine to standing has previously been extensively reported at a similar magnitude to this study in patients with hip dysplasia. 18,20,21 The correction in pelvic tilt required to orientate the CT images between APP and supine or standing positions has not previously been reported.…”

“…It has been suggested that acetabular retroversion results from an external rotation of the hemipelvis, which has previously been described after analysis of plain radiographs 5 and CT imaging of patients with hip dysplasia. 6 It is also well accepted that the pelvic position, particularly in terms of rotation in the sagittal plane, does significantly affect the appearance and interpretation of plain radiological signs, [7][8][9][10] as well as measurements from cross-sectional imaging. 3,11,12 In order to counteract this, imaging analysis is often preceded by correction of pelvic sagittal rotation to a predetermined plane.…”

Arthroscopic Treatment of FAI in Patients With Borderline Dysplasia: Letter to the Editor

“…Furthermore, patients experiencing anterior impingement might exhibit pelvic retroversion as a compensatory mechanism to alleviate pain, a situation that could potentially result in dynamic acetabular anteversion. 3 It has been reported that patients within the instability group experienced instances of femoral/acetabular version, as discussed earlier. Nonetheless, a commentary by Hohmann 2 proposed that excessive femoral anteversion and anterior acetabular undercoverage could be risk factors for unfavorable outcomes, potentially prompting acetabular anteversion as a compensatory response.…”

A leap towards personalized orthopaedic surgery and the prediction of spinopelvic mechanics in total hip arthroplasty

“…9-13 Surgeons who undertake this procedure must recognize that changes in the sagittal profile and balance could influence decisions about the functional orientation of the acetabular component. 14 Additionally, the classification proposed by Tang et al 1 may provide valuable insights into the longstanding debate regarding the sequence of surgical interventions – whether to address the hip or spine first in patients presenting with significant symptoms in both areas. For some of these patients, all compensatory reserves will have been exhausted, making THA unlikely to rectify the global balance significantly.…”