To The Editor: I read with great interest the article entitled “Influence of Acetabular Coverage on Hip Survival After Free Vascularized Fibular Grafting for Femoral Head Osteonecrosis,” (2006;88:2152-8), by Roush et al., and the commentary by Steinberg and Steinberg1. Indeed, this article and the commentary by Marvin Steinberg1 represent the views and thoughts of two senior authors with opposing opinions on how to treat osteonecrosis. Urbaniak2 supports vascularized bone-grafting, whereas Steinberg3 supports avascular cancellous bone-grafting. While the intent of the article by Roush et al. was not to document the clinical efficacy of either type of bone-grafting, the conclusions made therein invariably influence one's ability to recognize a potential limitation of free vascularized fibular grafting, and it is from this observation that I would like to offer a few comments. Roush et al. retrospectively reviewed a consecutive series of 200 hips in 160 patients with osteonecrosis of the femoral head who had undergone free vascularized fibular grafting. They found that, of the hips with a center-edge angle of ≤30°, 55% demonstrated progression of collapse and 45% were converted to a total hip arthroplasty. In contrast, of the hips with a center-edge angle of >30°, only 10% demonstrated progression of collapse and only 6% were converted to a total hip arthroplasty. Roush et al. encouraged the reader to consider acetabular dysplasia as an independent risk factor with a negative influence on prognosis and …