Posterior Pelvic Tilt From Supine to Standing in Patients With Symptomatic Developmental Dysplasia of the Hip

Abstract

Pelvic sagittal inclination (PSI) significantly affects the femoral head coverage by the acetabulum in patients with developmental dysplasia of the hip (DDH), while no reports have quantified PSI in DDH patients in the supine and standing positions. Furthermore, little is known about how PSI changes after periacetabular osteotomies. Herein, PSI in the supine and standing positions was quantified in DDH patients preoperatively and postoperatively. Twenty‐five patients with DDH who had undergone periacetabular osteotomies were analyzed. The preoperative PSI and the PSI 2 years after surgery were measured in the supine and standing positions using the image registration technique between radiographs and computed tomographic images. The percentage of patients who showed PSI changes of more than 10° from the supine to the standing position was quantified. PSI changed 8.2 ± 5.0° posteriorly from the supine to the standing position during the preoperative period. Posterior pelvic tilt of more than 10° was found in nine cases (36%). Two years after periacetabular osteotomies, the postural PSI change was 7.1 ± 3.9° posteriorly. When the preoperative and postoperative PSI values were compared, PSI in the standing position did not differ (p = 0.20). Similarly, the amount of PSI change from the supine to standing position was not significantly different (p = 0.26). In conclusion, posterior pelvic tilt in the standing position was found preoperatively in symptomatic DDH patients, and it remained for 2 years after periacetabular osteotomies. This postural change in PSI does not seem to influence the outcome of periacetabular osteotomy. However, during preoperative planning, surgeons should recognize that acetabular anteversion or anterior acetabular coverage differs between the supine and standing positions in some patients with DDH. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:578–587, 2020

What is the pelvic tilt in acetabular dysplasia and does it change following peri-acetabular osteotomy?

“…Second, the observed pelvic tilt in our cohort is equivalent to that found in the normal population (7.2°–12°) [ 27–29 ], and in patients with acetabular dysplasia (8.3° pre- and 6.2° post-PAO) [ 17 ]. Third, the pre-operative pelvic tilt in our cohort of patients with anterolateral undercoverage was not significantly higher than that seen in patients with symptomatic acetabular retroversion, as demonstrated by Grammatopoulos et al (4° ± 4°) [ 11 ].…”

“…These findings are supported by those of Tani et al . who evaluated the pelvic sagittal inclination (PSI) in patients with acetabular dysplasia with anterolateral under coverage and demonstrated neither significant difference in the pre-operative and post-operative PSI, nor the change in PSI [ 17 ]. Grammatopoulos et al .…”

“…Radiographs were considered adequate if the coccyx was in line with the pubic symphysis, and the iliac wings, obturator foramina and radiographic teardrops appeared symmetrical [ 22 , 23 ]. A distance of 1–3 cm from the coccyx to pubic symphysis was not used to evaluate image quality as this may vary with pelvic tilt, which was the subject of this investigation, and has been shown to vary beyond these limits in approximately half of patients with symptomatic acetabular dysplasia despite standardization of X-ray technique in a previous study [ 17 ].…”

“…However, in patients with acetabular dysplasia, this remains inadequately characterized. Furthermore, whether the pelvic tilt changes following correction of the acetabular deformity is still debated [ 11 , 17 , 18 ].…”

The effect of pelvic tilt on three‐dimensional coverage of the femoral head: A computational simulation study using patient‐specific anatomy

“…Collectively, our results indicate that change in regional coverage can be assumed by understanding the change in the PSI and confirmed the clinical importance of previous studies that quantified PSI in several postures for participants with FAIS and DDH. Recently, one study found a small change in PSI in the standing position following peri‐acetabular osteotomy as the PSI in supine and standing positions varied (Tani et al, 2019). The authors suggested that the PSI in the standing position should be referenced when developing surgical plans for peri‐acetabular osteotomy, which can be supported by our findings that PSI affects head coverage, especially in the anterior region.…”