The use of postoperative bone scintigraphy to predict graft retention

Osteonecrosis of the femoral head commonly occurs in patients aged under 50 years. Because of a high rate of complications associated with joint replacement surgery in this population, surgical techniques, such as vascularized fibular grafting, have been devised in an attempt to salvage the femoral head. The purpose of this study was to investigate the use of bone scintigraphy to predict graft retention after vascularized fibular grafting for osteonecrosis of the hip.

We evaluated single photon emission computed tomography images from 104 subjects whose hips were treated with vascularized fibular grafts between 1994 and 2000. We compared the signal intensity of the graft with the intensity of the ipsilateral proximal femoral diaphysis and assigned a score of 1 if less than diaphysis, 2 if equal to diaphysis and 3 if greater than diaphysis. We defined graft failure as conversion to or on the waiting list for total hip arthroplasty.

Thirty percent of hips failed treatment (n = 31, mean graft survival 34.9 mo), while 70% of grafts were retained (n = 73, mean follow-up 56.6 mo). Bone scan scores were significantly lower in the failed group (mean 7.1, range 6-12), compared with the retained group (mean 8.5, range 6-18; p = 0.03). Logistic regression demonstrated that a bone scan score > 6 was associated with graft retention (p = 0.028), with an odds ratio of 3.08 (range 1.13-8.40).

These results suggest that having a well-perfused graft in the early postoperative period improves the chances of graft retention in the future.