A 3-month-old female infant born to a 28-year-old primigravida is brought to the pediatric orthopedic clinic by her mother. The child was breech-presented at delivery. On examination, the left hip shows restricted abduction (30° instead of normal 60°), and a palpable clunk is felt when the hip is flexed and gently abducted. Ultrasound of the hip (Graf classification) shows a Type IIc hip. What is the most appropriate next step in management?