A Novel Method for Assessing the 3-dimensional Morphology of Cartilaginous Acetabulum Via Childhood Magnetic Resonance Imaging

Tomoyuki Nakamura; Akifusa Wada; Takahiro Natori; Kengo Kawaguchi; Kazuyuki Takamura; Haruhisa Yanagida; Toru Yamaguchi

doi:10.1097/BPO.0000000000002510

A Novel Method for Assessing the 3-dimensional Morphology of Cartilaginous Acetabulum Via Childhood Magnetic Resonance Imaging

J Pediatr Orthop. 2023 Nov-Dec;43(10):640-648. doi: 10.1097/BPO.0000000000002510. Epub 2023 Sep 8.

Authors

Tomoyuki Nakamura¹, Akifusa Wada², Takahiro Natori¹, Kengo Kawaguchi¹, Kazuyuki Takamura¹, Haruhisa Yanagida¹, Toru Yamaguchi¹

Affiliations

¹ Department of Othopaedic and Spine Surgery, Fukuoka Children's Hospital, Fukuoka.
² Department of Othopaedic Surgery, Saga Handicapped Children's Hospital, Saga, Saga Prefecture, Japan.

PMID: 37681305
DOI: 10.1097/BPO.0000000000002510

Abstract

Background: Periarticular cartilage is abundant in children, making evaluations of 3-dimensional (D) cartilaginous acetabular morphology using x-ray or computed tomography (CT) difficult. The study aimed to visualize the 3D cartilaginous acetabular morphology in normal children and patients with pediatric developmental dysplasia of the hip (DDH).

Methods: Magnetic resonance imaging (MRI) of 17 female children without acetabular dysplasia at 7.5 years and CT of 33 normal female adolescents with mature bones at 14.6 years were used as controls. Subjects were 26 female patients with unilateral DDH who underwent angulated Salter innominate osteotomy (A-SIO) at 5.5 years. Preoperative and postoperative MRIs were performed at 5.2 and 7.0 years, respectively. The MRI sequence was 3D-MEDIC. The medial intersection (point A) of the line connecting the centers of the bilateral femoral head and the femoral head were defined as point zero. The 3D coordinates (X, Y, Z) of the cartilaginous acetabular edge (point C) from anterior to posterior were calculated. Subsequently, a 3D scatter plot was created using 3D graph software. The subjects were divided into 6 groups, including control MRI, control CT, unaffected DDH before and after A-SIO, and affected DDH before and after A-SIO. The femoral head coverage ratio (FHCR: AC/AB) was used to quantify coverage and was compared in each group.

Results: In the control MRI group, the acetabular coverage was small anteriorly, largest anterolaterally, and gradually decreased posteriorly, similar to the bony acetabulum in adolescents. In the affected DDH before A-SIO group, the coverage was significantly lower than that of the control MRI and unaffected DDH groups. After A-SIO, the morphology improved beyond the unaffected DDH and the control MRI group.

Conclusions: The global defect of the cartilaginous acetabulum in the affected DDH group was significantly improved to normal morphology after A-SIO. Evaluating the cartilaginous acetabulum using MRI was useful for assessing hip morphology in childhood.

Level of evidence: Level III-retrospective comparative study.