The femoral head is supplied by the medial femoral circumflex artery and the obturator artery, and the supply is chiefly characterized by the prolonged intra-articular course of the vessels, partly in folds of the synovial membrane and partly in the ligamentum teres. The vessel branches to the head are comprised of parallel arteries and veins. Trochanteric fractures course lateral to the medial circumflex vessel, as distinguished from the fractures of the true neck, all of which are medial to this vessel. In the former type of fracture, therefore, this vessel with all its branches remains on the central fragment, while in neck fractures its branches must bridge the fracture in remnants of the synovial membrane.

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The method described for the performance of intra-osseous phlebography of the femoral head in neck fractures makes it possible to study the residual vascularity of the head fragment in different types of fractures. The types of venograms in neck fractures are positive in which the circumflex and ligamentum teres veins are filled with contrast material, and negative, in which no venous filling occurs. The negative venogram indicates avascularity but a good position of the cannula is required to show this.

Non-displaced fractures differ from displaced fractures mainly in that in the former the remaining circumflex vascularization is considerably better. There are fewer cases of this type of vascularization among patients with displaced fractures and in these the circumflex vascularization is usually limited to the inferior retinacular vessels. In these displaced fractures there is instead a ligamentum teres type of vascularization to a large extent, especially in older patients.

Forty-three patients with displaced neck fractures examined venographically were followed. There were twelve negative venograms which all showed early signs of necrosis. There were thirty-one patients with positive venograms of whom ten eventually showed manifestation of necrosis but a different type than the necrosis found after negative venograms. The method herein described makes possible the early definitive diagnosis of avascularity in at least half of the patients in whom it will later occur.