THE EFFECT OF ACTIVE MOVEMENT OF THE FOOT ON VENOUS-BLOOD FLOW AFTER TOTAL HIP-REPLACEMENT

Surgeons often encourage patients to move their feet in an attempt to prevent venous stasis, but there is little evidence that this measure is beneficial, We investigated the effect of active movement of one fo ot on the venous blood flow four days after total hip replacement. The actual venous outflow at rest was measured with use of venous occlusi on strain-gauge plethysmography in thirty-eight patients, The patients were randomly allocated to the control group (eighteen patients) or t he exercise group (twenty patients). A baseline measurement was follow ed by a one-minute period of rest (control group) or of maximum planta r flexion and dorsiflexion of the foot, ankle, and foes at a rate of t hirty cycles per minute (exercise group), The venous outflow was measu red again at two, seven, twelve, and thirty minutes in both groups. Mo vement of the foot for one minute produced a significant and sustained increase (p < 0.002) in the venous outflow (mean maximum increase, 22 per cent), The value remained greater than the baseline level for thi rty minutes (mean increase, 6.5 per cent) (p < 0.2), The increase was gradual, reaching a maximum twelve minutes after the completion of exe rcise. Our results confirm the beneficial hemodynamic effects of activ e movement of the foot in the postoperative period and suggest that pa tients should move the feet and ankles postoperatively as part of a pr ophylactic regimen directed at decreasing the risk of venous thrombosi s.