Elsevier

Journal of Orthopaedic Science

Volume 28, Issue 5, September 2023, Pages 1165-1168
Journal of Orthopaedic Science

Original Article
Location of the ovaries in children and efficacy of gonadal shielding in hip and pelvis radiography

https://doi.org/10.1016/j.jos.2022.07.012Get rights and content

Abstract

Background

Patients with hip disorders undergo multiple radiographic examinations, so gonadal radiation risk should be minimized. Inaccurate shield placement, including obscuring landmarks, has been widely reported, and some studies reported that covering the true pelvis was inappropriate to shield young girls’ ovaries. However, no reports on ovaries in Asian patients identified on magnetic resonance imaging exist. We aimed to identify the location of the ovaries in Japanese children and assess the efficacy of gonadal shielding.

Methods

Female patients aged ≤16 years who underwent magnetic resonance imaging for hip disorders that displayed at least one ovary were included. Sixty ovaries from 31 patients were classified into two age groups: <2 years and >2 years, and the ovaries' position was classified according to the following four zones on the anteroposterior pelvic radiograph: zone 1 (true pelvis) — area surrounded by the line of the anterior superior iliac spines, inner side walls of the ilium, and symphysis pubis; zone 2 — areas lateral to zone 1; zone 3 — sacral area superior to zone 1; and zone 4 — areas lateral to zone 3. The ovaries’ position was analyzed according to age group.

Results

Thirty-one ovaries in 16 patients were <2 years, and 29 ovaries in 15 patients were >2 years. Thirteen ovaries in the true pelvis, 18 ovaries in the false pelvis were <2 years, and 27 in the true pelvis and 2 in the false pelvis were in >2 years. In girls aged <2 years, most ovaries in the false pelvis were located in zone 3.

Conclusions

Girls aged >2 years mostly have their ovaries in the true pelvis, and ovaries in infants tend to be located superior to the true pelvis. Covering the true pelvis is plausible for shielding ovaries. Shields should be placed slightly more cranially than the true pelvis for infants.

Introduction

Children's organs are more sensitive to radiation than adults, and the radiation dose should be limited to as low as reasonably achievable. Patients with hip disorders such as developmental dysplasia of the hip (DDH) undergo multiple pelvic radiographic examinations; therefore, each gonadal radiation risk should be minimized.

Accurately placing a gonadal shield on the girls' pelvis can be difficult. Many studies have reported a high rate of inaccurate placement of shields, including obscuring critical landmarks [[1], [2], [3], [4], [5], [6], [7]]. Some institutions even abandon gonadal shielding to avoid re-examination due to incorrect placement of the shield. Some studies have reported that young children's ovaries are often located outside the true pelvis, and covering the true pelvis is inappropriate to shield their ovaries [8,9]. These previous reports have raised the concern that shielding does more harm than good.

Reports that have identified ovaries on magnetic resonance imaging (MRI) are scarce, and no study has been conducted in Asians. Therefore, we aimed to identify the location of the ovaries in Japanese children and assess the efficacy of gonadal shielding.

Section snippets

Materials and methods

This study has been approved by the IRB of the authors’ affiliated institution.

Female patients aged ≤16 years who underwent pelvic MRI examinations for hip disorders between January 2010 and July 2021 were included in the study. MRI scans showing at least one ovary were analyzed. Repeated examinations of the same patient were excluded.

Sixty ovaries from 31 patients were analyzed in the study. Both ovaries were identified in 29 patients, and only one ovary was identified in two patients. The

Results

Sixty ovaries from 31 patients were evaluated. No cases with a chromosomal abnormality or gonadal disease were included. Right or left ovaries were identified in 30 patients each. No significant difference was observed between the positions of the right and left ovaries (p = 0.940) (Table 1).

In the <2 years group, 31 ovaries in 16 patients with a mean age of 0.5 (range, 0.2–1) years were included. In the >2 years group, 29 ovaries in 15 patients with a mean age of 8.9 (range, 3–16) years were

Discussion

Pelvic radiography is essential for the diagnosis and observation of pediatric hip disorders. Although gonadal radiation exposure must be minimized, accurate positioning of the gonadal shield on the pelvis of girls is difficult. Especially for DDH, obscuring the landmarks that are necessary to evaluate the acetabular index or the Shenton line is a critical failure, and re-examination might be necessary. Inaccurate gonadal shield placement has been reported previously [[1], [2], [3], [4], [5],

Conclusions

Girls after infancy mostly have their ovaries in the true pelvis, and ovaries in infants tend to be located slightly superior to the true pelvis. Covering the true pelvis may shield the ovaries of girls. Thus, gonadal shields should not be abandoned and should be placed slightly more cranially than the true pelvis to more accurately shield the ovaries of infants and avoid obscuring the critical landmarks for diagnosis.

Ethical approval

This study was approved by the institutional review board of our institution. Informed consent has been obtained in the form of opt-out for this retrospective study.

Declaration of competing interest

None.

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