Make the Diagnosis: Summer 2022

TD is a 25-month-old female who presented to clinic with a complaint of bowed legs. Mom reports that throughout infancy, both legs were bowed, but the right one straightened out while the left appears to have worsened. She was an early walker at 10 months and is of Latino background. Mom feels she may in-toe a bit more on the left as well. She does not appear to have pain and has met all her developmental milestone appropriately. She has no known nutritional deficiencies.

On examination, she has varus of the left leg. She has a lateral thrust on the left side when walking. Her foot progression angle is 0 on the right, and 5 degrees in on the left. Prone internal rotation of the hip is 75 degrees bilaterally, external is 50 degrees bilaterally. Thigh foot angle is 0 on the right, 5 degrees in on the left. She is 50th percentile for height and 90th percentile for weight. She has a normal neurologic exam.

An X-ray was performed and is shown here.

What is the most likely diagnosis?