A 14-month-old boy is brought to the orthopedic clinic by his parents with complaints of an asymmetric gait and frequent falls over the past 2 months. The child was born via normal vaginal delivery and is the second child in the family (first child had no orthopedic issues). On examination, the left hip shows limited internal rotation (15° instead of normal 40°) and positive Trendelenburg sign. Plain radiographs of the pelvis show a shallow acetabulum on the left side with delayed ossification of the femoral head epiphysis. The child has no history of trauma or systemic illness. What is the most likely diagnosis?