Slipped Capital Femoral Epiphysis

A 13-year-old boy presents to the orthopedic clinic with a 3-week history of progressive left groin pain and a limp. His mother reports he has gained significant weight over the past year. On examination, the left hip is held in flexion, abduction, and external rotation. Internal rotation of the left hip is markedly limited and painful. Plain radiographs of the pelvis show displacement of the left femoral head posteromedially with respect to the femoral neck. What is the most appropriate initial management for this patient?

A 14-year-old girl with a history of hypothyroidism presents with bilateral hip pain and a waddling gait of 6 months' duration. She reports pain in the groin and medial thigh, worse with activity. On examination, both hips show limited internal rotation and abduction. Pelvic radiographs reveal bilateral posteromedial displacement of the femoral heads with respect to the femoral necks, more pronounced on the right side. The right slip measures 40° on the lateral view. What is the most likely complication if this patient does not receive appropriate treatment?