Background:The angiography with micro-computed tomography (micro-CT) has been proved its great advantages on investigating the intra-osseous vascularity of carpal bones.But few researches have focused on the intra-hamate vascularity.This study aimed to illustrate the intra-osseous arteries of the hamate and the relationship between the intra-hamate vascularity and the avascular risk of different types of hamate fractures.Methods:Six normal cadaveric hamates were investigated with red lead (Pb3O4) micro-CT angiography.The intra-osseous arteries of specimens were clearly enhanced and the three-dimensional model was reconstructed.In order to study the features of the arterial entrances and intra-hamate vascularity,the diameters,quantities,locations of enhanced arteries,and the locations of transversal/proximal pole fracture lines on the body of the hamate were statistically compared.Besides,in order to analyze the relationship between intra-hamate vascularities and different hamate fractures,127 cases of hamate fractures who presented in our hospital from March 2003 to June 2017 were retrospectively studied.Results:A total of 94 cases were followed up (range:4-37 months;mean:12.4 months) effectively.The overall union rate of hamate fractures was as high as 92.6％ (87 of 94 cases),while non-union of fracture on hamate hook was more common (P =0.031).The arterial entrances were located around the dorsal,volar,radial,ulnar non-articular surfaces of the hamate body and the hook of the hamate.Generally,there were one to two trunk arteries on the volar non-articular surface and one to three trunk arteries on the dorsal non-articular surface.They formed one or two arterial arches,from which some branches were emitted and supplied the proximal parts.The intra-osseous vascularities of the hamate body were generally located in the radial part.The blood supply of the hook was mainly from the volar non-articular surface in most specimens.Hamate fractures could be classified into four types:fractures of the transversal/proximal pole,medial tuberosity,dorsal coronal ofthe hamate body,and fractures of the hamate hook.Conclusions:This study showed new features of intra-hamate vascularity and the results will guide surgeons to reduce the vascular damage during the hamate fracture operations.The fracture lines of different types of hamate fractures may disrupt the intra-hamate arteries.The intra-hamate vascularities will have different influences on the avascular risks of different hamate fractures.