The case report presents a 12-year-old boy who developed two years after a nondisplaced fracture of the femoral neck a polar avascular necrosis of the femoral head (ANFH), with partial closure of capital physis and progressive limb shortening of 2 cm. Based on preoperative MRI scans in the frontal and sagittal planes, the intertrochanteric valgus-extension osteotomy was performed two years after injury.
Postoperative MRI scans confirmed correct preoperative planning, 7 years after osteotomy there are no signs of ANFH. This case documents that MRI is a suitable method for preoperative planning and postoperative follow-up in adolescent patients with partial ANFH.