for the RECOS InvestigatorsThe incidence of venous thromboembolism (VTE) after hip and knee major surgery without prophylaxis ranges from 29% to 60% for deep vein thrombosis (DVT) and from 1% to 3% for fatal pulmonary embolism (PE) 1-3 ; consequently, thromboprophylaxis in this clinical setting is strongly recommended by experts and international consensus guidelines. Conversely, limited information is available on the rate of VTE complications and thromboprophylaxis use in other orthopaedic surgeries, such as shoulder arthroscopy. 4 To the best of our knowledge, the incidence and risk factors for VTE in shoulder arthroscopy haven't been investigated in prospective epidemiological studies. Some independent, retrospective, observational studies and case series have reported a quite low VTE rate in shoulder arthroscopy [5][6][7][8][9][10][11][12] ; moreover, a few information is available on the safety and efficacy of thromboprophylaxis in this setting. Thus, current guidelines on the prevention of VTE in patients undergoing orthopedic surgery do not have a specific recommendation for those undergoing shoulder arthroscopy. In the recently published RECOS registry, we prospectively evaluated the incidence of symptomatic VTE following different types of shoulder surgery (arthroscopy, hemiarthroplasty, total replacement, and fixation for proximal humeral fracture.13 Furthermore, risk factors for VTE and thromboprophylactic practices in this population have also been analyzed.Here, we report the results of the RECOS registry in the specific group of patients undergoing shoulder arthroscopy. Study protocol and inclusion and exclusion criteria were already explained in a previous publication. 13 Briefly, from June 2009 to June 2011, 9 Italian centers participated in the registry and 1366 patients were enrolled. For each included patients, demographic characteristics, data regarding surgery, use of antithrombotic prophylaxis, potential VTE risk factors, and symptomatic objectively diagnosed VTE during 90 days follow-up were recorded. The decision to initiate thromboprophylaxis (as well as type, dose, and duration) was left to the investigators. Due to the low incidence (0.66%) of VTE in the whole population, only the following common potential VTE risk factors were evaluated for this study: gender, age, duration of surgery > 60 minutes, and body mass index (BMI) > 30 kg/m 2 . For the study purpose, the incidence of VTE after surgery in the whole population, and in the subgroups of patients in which antithrombotic prophylaxis was or was not prescribed, was assessed. Furthermore, results of subgroup analyses of patients with and without potential risk factors for VTE were presented to characterize subgroups at particular high or low risk of VTE. Incidences of VTE at the end of follow-up in the whole population and in specific subgroups were provided as percentages with the corresponding 95% confidence intervals (with continuity correction).Of the whole population, 982 (71.9%) patients underwent shoulder arthroscopy. The ...