USMLE® Step 1 style questions USMLE
A 4-year-old girl is brought to the emergency department by her parent after a fall. The patient was running on the playground when she tripped and fell onto the mulch. She did not hit her head or lose consciousness. Past medical history is significant for several fractures that occured after minor trauma. Her parent also has a history of multiple fractures. The patient has been meeting most developmental goals but is experiencing language delays, for which she is scheduled to receive a hearing test in the upcoming week. The patient is at 15th and 20th percentile for height and weight, respectively. Vitals are within normal limits. Physical examination shows bruising along the left lateral thigh, knee, and elbow. Kyphoscoliosis is also noted. Examination of the patient’s oropharynx reveals the following finding:
Image reproduced from Wikimedia Commons
Laboratory results are within normal limits. Plain radiograph shows a fracture of the olecranon. Which of the following is the most likely explanation for the patient’s presentation?
Osteogenesis imperfecta (OI) is a genetic bone disorder characterized by impaired production of type 1 collagen, an essential protein in the development and maintenance of bones and connective tissue. Collagen provides strength and support to the bones, and in individuals with OI, the collagen produced is weak, leading to bones that are brittle and prone to fractures.
OI may present with shorter height and neurological features, including communicating hydrocephalus, basilar invagination, seizures, blue sclerae, hearing loss, and other complications. Associated fractures may cause acute or chronic pain, reduced quality of life, and depression.