Thromboembolic complications after arthroscopic knee surgery. Incidence and risk factors in 101 patients

Deep venous thrombosis (DVT) and pulmonary embolism (PE) are less common after knee arthroscopy than after elective hip and knee arthroplasties. There is no consensus on the optimal prophylaxis. In this prospective cohort study, we used ultrasound, phlebography and lung scan pre- and postoperatively to assess the incidence of thromboembolic complications in 101 consecutive patients who underwent knee arthroscopy. Preoperatively, patients were screened for typical risk factors for DVT such as age, obesity, varicose veins, contraceptive pills and nicotine abuse. All patients received a once-daily injection of 5000 IU of low molecular weight heparin, at least 12 hours prior to surgery. 5 weeks after surgery, the same screening tests were repeated. In 12 of the 101 patients either DVT or PE was diagnosed. DVT occurred in 8 cases, 4 of which were silent and 4 symptomatic. The number of PEs was 9, 8 silent and 1 symptomatic. We found no correlation between DVT or PE and individual clinical risk factors, but there was a tendency towards the development of DVT and PE, with a higher number of risk factors. We found no correlation between DVT and intraoperative risk factors such as use of a tourniquet, type of anesthesia or duration of surgery. The relatively high rate of thromboembolic events after knee arthroscopy in our study suggests the need of all patients for routine use of thromboprophylaxis, probably in a higher dose than given.