Vascular endothelial growth factor for the treatment of femoral head osteonecrosis: An experimental study in canines

AIM To evaluate the treatment of osteonecrosis of the femoral head (ONFH) with the use of vascular endothelial growth factor (VEGF). METHODS In 30 mature beagles (6 groups of 5 beagles) ONFH was induced cryosurgically and one of the following solutions was administered locally in the femoral head (FH) in each group: Single injection of 500 mu g VEGF (t-VEGF mu group); single injection of 500 ng VEGF (t-VEGFn group); continuous delivery of 500 mu g VEGF through osmotic micropump (t-VEGFpump-mu group); continuous delivery of 500 ng VEGF through osmotic micropump (t-VEGFpump-n group); single injection of 0.9% sodium chloride (t-NS group), while one group that served as control group did not receive any local solution (No-t group). FHs were retrieved 12 wk postoperatively, underwent decalcification and hematoxylin/eosin and toluidine blue staining. In two canines per group, one half of FH was processed without decalcification and stained with modified Masson Trichrome. Histological sections were observed by light microscopy and measured with a semi-automatized bone histomorphometry system and Bone Volume/Total Volume (BV/TV), Marrow Volume/Total Volume (MaV/TV), and Trabecular Thickness (TbTh) were assessed. Standard and robust tests (Welch, Brown Forsythe) of analysis of variance along with multiple comparisons, were carried out among the categories. RESULTS The untreated (No-t) group had signs of osteonecrosis, whereas the VEGF groups revealed reversal of the osteonecrosis. Statistical analysis of the decalcified specimens revealed a significantly better BV/TV ratio and a higher TbTh between the VEGF treatment groups (except the t-VEGFn group) and the No-t group or the control t-NS group. Single dose 500 mu gVEGF group had significantly better BV/TV ratio and higher TbTh when compared to the No-t group (50.45 +/- 6.18 vs 29.50 +/- 12.27, P = 0.002 and 151.44 +/- 19.07 vs 107.77 +/- 35.15, P = 0.161 respectively) and the control t-NS group (50.45 +/- 6.18 vs 30.9 +/- 6.67, P = 0.004 and 151.44 +/- 19.07 vs 107.14 +/- 35.71, P = 0.151 respectively). Similar differences were found for the prolonged VEGF delivery/pump groups of 500 mu g and 500 ng. Analysis of the totality of specimens (decalcified/non-decalcified) enhanced the aforementioned differences and additionally revealed significant differences in the comparison of the TbTh. CONCLUSION In an experimental model of ONFH in canines it was found that local treatment with VEGF leads to bone tissue remodeling and new bone formation.