Intermittent Calf Compression: A Randomized Trial In Elective Hip Replacement

Abstract

We have evaluated venous thrombosis prevention with intermittent calf compression in 78 patients aged over 50 years having elective hip replacement. 38 patients were randomly allotted to intermittent calf compression with a “BOC-Roberts Venous Flow Stimulator”, begun at the start of surgery and continued for 7 days, while 40 patients had no prophylaxis. Age, weight, length of surgery, and other risk factors were similar in the two groups. All patients had ascending venography of the operated leg on the seventh day, or bilateral venography if routine 125I fibrinogen legscanning and impedance plethysmography suggested thrombosis on the unoperated side.Venography showed thrombosis in 12/38 patients treated with intermittent calf compression (32%) and 21/40 untreated patients (53%). The difference is not statistically significant, but further analysis showed some interesting treatment effects: (a) calf vein thrombosis was found in 13% of treated and 35% of untreated patients (p <0.05), (b) femoral or popliteal vein thrombosis developed in 24% of treated and 38% of untreated patients, while isolated femoral vein thrombosis (without calf vein thrombosis) developed in 18% of treated and untreated patients, but (c) the femoral vein thrombi were smaller in treated patients - 8% of treated and 30% of untreated patients had femoral vein thrombi with an estimated length above 5 cm (p <0.05).This suggests that intermittent calf compression prevents calf vein thrombosis and prevents extension of femoral vein thrombi after elective hip replacement, although it cannot prevent the initiation of femoral vein thrombi which is presumably due largely to local vein trauma. This limited effect may be clinically valuable, allowing delay in starting anticoagulant prophylaxis until this is safe.