Aim: To investigate the incidence and type of venous thromboembolic event (VTE) diagnosed in patients undergoing total knee arthroplasty (TKA) and the trends over time following the introduction of a rigorously enforced thromboprophylaxis protocol.

Methods: Data from all 3260 TKAs performed in our unit between April 1996 and March 2003 were prospectively collected by the Scottish Arthroplasty Project (SAP). The SAP data identified 84 of these patients as having being admitted with or died from a VTE episode. A unified thromboprophylaxis protocol was introduced in 1999, from 2001 it was included as part of the integrated care pathway. We retrospectively reviewed all available casenotes of these patients to identify the assessment and thromboprophylaxis given, the precise diagnosis of VTE, the treatment and adverse outcomes.

Results: Of the 84 VTEs identified, 29 had pulmonary emboli (PE), 12 had above knee deep vein thrombosis (DVT), 24 had calf DVT and 10 had no evidence of VTE though were coded as such (but not treated) by physicians elsewhere. Data were unavailable for the remaining 9 but these were assumed to have had VTE for the purposes of this study. Of the 24 patients with calf only DVT, 16 were given therapeutic anticoagulation of whom five developed haemorrhagic complications. From 2001 the thromboprophylaxis protocol was followed in 100% of patients. The rate of VTE in our unit has fallen steadily from 2.26% in 1996–7 to 1.05% in 2002–3.

Conclusions: There has been a steady decline in the rate of venous thromboembolism in our unit over the seven years of the study. A thromboprophylaxis protocol has been successfully introduced in our unit and consistently applied since 2001. There is considerable overdiagnosis and treatment of calf DVT with significant resultant morbidity.