A 6-month-old infant, born to average-stature parents, presents for a well-child check. Examination reveals rhizomelic limb shortening, a long narrow trunk, and a large head with a prominent forehead. A thoracolumbar gibbus is noted. What is the most likely genetic mechanism underlying this infant’s condition?
A 12-year-old pitcher presents with several weeks of medial elbow pain that is worst during the acceleration phase of throwing. He has focal tenderness over the medial epicondyle. Radiographs show widening of the growth plate at the medial apophysis compared to the contralateral elbow. Which diagnosis is most consistent with these findings?
A 7-year-old boy with Down syndrome presents with a new-onset clumsy gait and increased tripping over the past month. On examination, he has hyperreflexia and a positive Babinski sign. A lateral cervical spine radiograph in flexion reveals an atlanto-dens interval (ADI) of 8 mm. Which of the following is the most appropriate next step in management?
A 4-year-old girl is brought to the clinic due to an in-toeing gait. On prone examination, her hip internal rotation is 80 degrees bilaterally, and external rotation is limited to 10 degrees. Her thigh-foot angle and foot shape are normal. What is the most likely cause of her in-toeing?
An 11-year-old girl presents with several months of activity-related foot pain and recurrent “ankle sprains.” Examination reveals a rigid, painful flatfoot with peroneal muscle spasm. An oblique radiograph of the foot reveals an elongation of the anterior process of the calcaneus, known as the “anteater sign. Which of the following is the most likely diagnosis?
A 4-year-old presents with a limp, and an MRI confirms a diagnosis of pyomyositis of the pelvic muscles. This condition can present similarly to pelvic osteomyelitis with fever and pain. What is the most common causative organism for pyomyositis?
A 6-year-old child sustains a posterolaterally displaced supracondylar humerus fracture after a fall. On examination, the physician notes the child is unable to make an “OK” sign by flexing the interphalangeal joint of the thumb and the distal interphalangeal joint of the index finger. Sensation is decreased over the tip of the index finger. Which nerve is most likely injured?
A 16-year-old female basketball player sustains a noncontact injury to her right knee while pivoting. She reports hearing a “pop” followed by immediate swelling and a feeling of instability. What is the most likely ligamentous injury?
A newborn infant is noted to have a “bean-shaped” foot with a convex lateral border and adduction of the forefoot relative to the hindfoot. Ankle and subtalar motion are normal. The deformity is flexible and can be corrected to a neutral position with gentle pressure. What is the most likely diagnosis?
An infant is diagnosed with a skeletal dysplasia characterized by rhizomelic shortening, frontal bossing, and a depressed nasal bridge. A skeletal survey is performed. Which radiographic finding is pathognomonic for achondroplasia?
