Treatment of Avascular Necrosis of the Femoral Head with a Vascularized Scapular Bone Graft

Introduction: Treatment of avascular necrosis of the femoral head is still a challenge especially for young patients. Among various surgical options being proposed so far, vascularized bone graft is the most ideal due to its ability of providing both strong mechanical support to prevent collapse of the necrotized area and introducing rich vascularity deep into the necrotized bone. Among common donor sites for vascularized bone graft, scapular has several definite advantages, i.e., 1. the nourishing vessels run a constant course with minimal anatomical variations, 2. long vascular pedicle that can be extended up to 110 mm by including the subscapular artery, 3. due to its direct medullary branch, scapular can be can be fabricated as bone struts with one cortical and three cancellous surfaces without jeopardizing tissue vascularity, which enhances vascular and bone ingrowth into the surrounding areas.

Methodology and Material: With above mentioned characteristics in mind, we have applied vascularized scapular bone grafts to 9 hips in 7 patients. The male to female ratio was 4:3 and average patients’ age at the time of surgery was 24. 7 patients was diagnosed as idiopathic, 1 as post-traumatic, and 1 as steroid induced. The average follow up duration was 12 years. According to the Japanese Ministry of Health, Labor and Welfare type classification and disease staging, two were judged as type B-2, 3 as type C-1, and 4 as type C-2 and all were in stage II before surgery. The hips were followed up using a conventional radiography, CT, and MRI. In addition, circulation of grafted bone strut was evaluated semi-quantitatively with dynamic MRI one week and 7 months after surgery.

Results: At the final follow-up, the average score increased from 56 to 85 during the follow-up period. Five joints remained in Stage2, and 4 joints progressed to Stage III or IV. In all cases dynamic MRI study at 7 months demonstrated a mild to moderate rise suggestive of vascular ingrowth into the subchondral bone of the femoral head.

Conclusions: These results indicate that vascularized scapular bone graft is a valid option for young patients with stage 2 avascular necrosis of the femoral head