Femoral vein occlusion during hip arthroplasty.

The mechanism of femoral vein occlusion when the hip joint is dislocated and manipulated during arthroplasty has been studied in fresh anatomic specimens. Flow studies show that moderate degrees of flexion and adduction in association with dislocation obstruct venous flow just distal to the femoral sheath at normal pressures and flow rates. Internal femoral rotation during a posterior approach to the hip causes "scissoring" of the femoral vein between femur and pubic bone. External femoral rotation during an anterior approach does not occlude flow. Injection of Batson's acrylic and neoprene latex showed that obstruction is also due to about 4 cm of shortening caused by proximal migration of the femur after dislocation in association with adduction and flexion. The femoral vein in the unsupported segment distal to the femoral sheath subsequently buckles and kinks. During operative manipulation, intermittent obstruction at this level is therefore likely to cause intermittent venous distension distally. This mechanism depletes the femoral vein of fibrinolytic activity distal to the occlusion and may explain the incidence of deep femoral thrombosis peculiar to this procedure.