Morphological Asymmetry of Pelvic Rings: A Study Based on Three‐Dimensional Deviation Analysis

Abstract

Objective: To evaluate the morphological asymmetry of pelvic rings existing in healthy individuals in terms of threedimensional (3D) geometric shapes.Methods: This study was a retrospective self-control study. CT images of healthy pelvises, scanned from Jan 2014 to Jan 2019, were taken from 159 subjects (88 males and 71 females) aged 20 to 59 years (39.1 AE 8.7 years). Digital pelvic ring models were reconstructed from CT images and then flipped over the corresponding sagittal planes to obtain their mirrored models. A 3D deviation analysis of a pelvic ring was conducted between the original model and its mirrored model via model registration and quantification of the geometric differences. Next, the pelvic rings were split to the left and right hipbones. The same flipping procedures as done by pelvic rings were performed for left hipbones to obtain their mirrored models. A 3D deviation analysis was also performed between the left and right hip bones. Quantitative variables representing deviation mainly included the average deviation (AD) and the maximum deviation (MD). MDs over 4 mm and 10 mm were deemed as critical levels for evaluating the severity of asymmetry as per Matta's scoring system. The quantitative assessments of the asymmetry covered pelvic rings, bilateral hip bones and the specific anatomic regions of a hip bone.Results: 157 out of 159 pelvic rings (98.74%) had more than 4 mm of the MD and 27 (16.98%) of them exceeded 10 mm of the MD. The MD of pelvic rings was 1.23 times as high as that for the bilateral hip bones (7.46 mm vs. 6.08 mm, P < 0.05). The ADs of pelvic rings and bilateral hip bones were 1.28 mm and 0.94 mm, respectively (P < 0.05); 2.27% of the surface points of a pelvic ring had more than 4 mm geometric deviations compared with its mirrored model, while 0.59% (P < 0.05) of bilateral hip bones were on the same level of deviation. 119 out of 159 pelvic iliac crests (74.8%) had MDs more than 4 mm, and 15 (9.4%) reached 10 mm or more. Only 15 (9.4%) pelvises presented asymmetric features in the area of obturator foramen where the MDs exceeded 4 mm.Conclusions: Pelvic asymmetry exists in the general population, but 3D geometric symmetry is present in specific anatomic regions. It implies that restoring the 3D symmetry of specific anatomic regions is more reliable than "restoring the symmetry of pelvic ring" in pelvic ring reduction or pelvic fixation design.

Asymmetry of the pelvis in Polish young adults

“…Greater asymmetry was found in men. Such a high percentage of iliac crest asymmetry confirms the previous observations of the authors as well as other researchers ( Brady et al, 2003 ; Kurki, 2017 ; Mundorf et al, 2021 ; Zhang et al, 2022a ). ASIS asymmetries were observed equally often.…”

“…Based on them, diagnostic schemes and therapy recommendations are developed. They are reliable, repetitive and accurate ( Lee et al, 2015 ; Kurki, 2017 ; Handrich et al, 2021 ; Zhang et al, 2022a ). Parallel to the radiologic examinations, methods based on palpation of the selected landmarks in the pelvic girdle area are used.…”

Both‐column Acetabular Fractures with Posterior Wall Involved can be Managed through Single Anterior Approach by Evaluation of Computer‐assisted Virtual Surgery Technique

“…Although, Zhang et al . published data that the pelvic ring was asymmetrical, yet the difference in number was small 34 . Hence, the mirrored acetabulum could be selected as a template for reduction.…”

The mystery of morphometric measurements of the coxal bone

“…Although the pelvic ring is considered to be a symmetrical entity, asymmetry in the pelvic ring may occur due to changes in its anatomy, function or biomechanics, or when clinical cases are affected by treatment. This condition can also be caused by degenerative or inflammatory processes [14].…”