Deep-vein thrombosis (DVT) and pulmonary embolism (PE) represent life-threatening postoperative complications frequently responsible for in-hospital mortality following total knee arthroplasty (TKA). Mechanical prophylaxis in the form of a foot pump offers an alternative to pharmacological and physical therapy. The aim of this prospective and randomised study was to examine the clinical efficacy of the A-V Impulse (AVI) system in reduction of soft-tissue swelling of the lower limb following a TKA. A total of 80 patients undergoing cemented TKA between September 2005 and December 2006 were randomised into two groups of 40 patients (n¹ = 40, n² = 40) during the 16-month study period. All patients received a subcutaneous dose of low molecular weight heparin (LMWH) (Enoxaparin/Clexane® 40 mg) once daily beginning 24 hours prior to the operation. The mean age for the groups n¹ and n² were 68.93 and 68.15 years, respectively. The reduction of soft-tissue swelling in the n¹ group was significantly higher (p < 0.05) compared with n². Evaluation of body mass index (BMI) with regard to the average reduction of soft-tissue swelling showed no significant influence (p < 0.05). The better function of the operated knee in group AVI was a significant predictor for improved agility and mobility (p < 0.01). No complications were reported for the application of the AVI. No ultrasonographic evidence of DVT or PE was found in any of the 80 patients during the investigative time period of eight days. After three months, there was no evidence of a symptomatic DVT.