Knee arthroscopy and venous blood flow in the lower leg

We conducted a series of duplex ultrasound examinations to evaluate the venous blood flow in the lower leg during arthroscopic knee surgery. All knees were placed in loosely fitted leg-holder, without a tourniquet. The flow velocity in and the diameter and area of one of the posterior tibial veins and the great saphenous vein were measured just above the ankle at 0, 100, and 180 mmHg of intraarticular pressure (IAP). All recordings were done with the lower leg dependent and the thigh both supported and unsupported by the leg-holder. The diameter and cross-sectional area of the veins were not influenced by the IAP or by the position of the thigh in the leg-holder. There was, however, a significant increase in the venous blood flow velocity in the great saphenous vein each time the thigh was placed in the leg-holder. A simultaneous decrease in the flow velocity was seen in the posterior tibial vein and this was statistically significant at 180 mmHg IAP. Our findings indicate an additive effect of external compression of the thigh by a leg-holder and an increased IAP, which causes a redistribution of the venous flow in the lower leg from the deep system to the superficial one.