Anatomic study of femoral vein occlusion during simulated hip arthroplasty.

An anatomic study was undertaken to establish whether positioning of the leg and surgical approaches for total hip replacement (THR) cause changes in the femoral v. which may contribute to the development of deep vein thrombosis (DVT). The patency of 32 femoral vv. of 18 cadavers was inspected at different levels during simulated THR. Before and after removal of the femoral head through a transgluteal or posterior approach, a wide-angle endoscope was inserted into the femoral v. via the external iliac v. Blood flow was simulated by proximal irrigation with saline through the popliteal v. After removal of the femoral head distinct changes were observed in both approaches. In the transgluteal approach the changes were dependent on the degree of adduction and the body build of the cadaver. Initially, an oval form was seen in a constricted lumen with an increasingly oblique oval deformation and a final facet-like closure, usually at about 5 to 7.5 cm below the inguinal ligament. In total adduction this stenosis occurred regardless of build. Using a posterior approach, the necessary internal rotation caused a closure of the vein in 50% of cases. In combination with flexion and adduction there was stenosis in all cadavers regardless of body build. Our results indicate that the duration of the adducted position of the thigh during THR via a transgluteal approach should be minimised, as there is a reduction in blood flow with even minor degrees of adduction. In the posterior approach the stenosis occurs earlier, and is independent of the build of the cadaver.