A girl with an abnormal gaitBMJ 2016; 355 doi: https://doi.org/10.1136/bmj.i5216 (Published 19 October 2016) Cite this as: BMJ 2016;355:i5216
- 1Department of Paediatrics, the Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
- 2Department of Infection and Liver Diseases, Liver Research Center, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
- Correspondence to: M-H Zheng
A 1 year old girl presented to the paediatric orthopaedic clinic with abnormal gait. Her parents noticed that she had a “duck-like” waddle when she had first started to walk a month previously. On examination, there were asymmetrical skin creases on her buttocks, and her legs were of similar length. There were no other external congenital malformations. Anteroposterior radiography of the infant’s pelvis was carried out (fig 1⇓). What is the diagnosis?
Bilateral developmental dysplasia of the hip.
The image shows changes typical of developmental dysplasia of the hip (DDH). Bilateral delayed ossification at the centre of the femoral head is visible in the lower outer quadrant (fig 2⇓, arrows A and B), which indicates bilateral developmental subluxation of the hip. The acetabular index (AI) was calculated using the angle formed by the acetabular roof line and the Hilgenreiner’s line (fig 2⇓, angles 1 and 2).1 A large AI (>30°) suggests a tendency towards hip dislocation. Also visible were bilateral disrupted Shenton’s lines, which are defined by the superior border of the obturator foramen and the medial border of the femoral neck (fig 2⇓, arrow C). This finding indicates cranial displacement of the femoral head from the acetabulum. Two shallow acetabulums and asymmetrical skinfolds were evident (fig 2⇓, arrow D).
DDH refers to a continuum of abnormalities in the immature hip, ranging from mild instability or subluxation to permanent dislocation. About 20% of cases are bilateral, which causes the legs to be non-discrepant in length. It is unusual for parents to identify the deformity at an early stage. To facilitate early diagnosis of DDH, ultrasonography is routinely performed for infants aged less than 6 months who are at risk (breech presentation, or a strong family history of DDH or breech birth). Multiple characteristics on plain radiographs of the pelvis are useful to diagnose the condition in infants older than 6 months. In addition, asymmetrical skin creases may be a useful indicator for unilateral or bilateral DDH.
Competing interests: We have read and understood the BMJ policy on declaration of interests and declare the following: none.
Provenance and peer review: Not commissioned; externally peer reviewed.
Patient consent: Obtained.