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Developmental dysplasia of the hip — USMLE Step 2 CK MCQ

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HardPediatricsDevelopmental dysplasia of the hipUSMLE Step 2 CK

A 7-month-old girl has asymmetric thigh folds and restricted abduction of the left hip. She was born breech and had no newborn hip imaging. She is afebrile and bears weight symmetrically when supported. What is the most appropriate next step?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Obtain anteroposterior and frog-leg pelvic radiographs and refer to orthopedics

Explanation lettering: B = shown as A · D = shown as B · E = shown as C · A = shown as D · C = shown as E

A is correct: after about 4 months, femoral-head ossification makes pelvic radiography appropriate, and limited abduction after the neonatal period warrants orthopedic referral. B uses the preferred modality for a younger infant and inappropriately conditions referral on complete dislocation. C ignores a current abnormal examination and breech risk. D starts treatment without defining anatomy or specialist input. E adds unnecessary sedation and is not first-line.

Reference: American Academy of Pediatrics: evaluation and referral for developmental dysplasia of the hip. https://publications.aap.org/pediatrics/article/138/6/e20163107/52541/Evaluation-and-Referral-for-Developmental