The impact of risk assessment on the implementation of venous thromboembolism prophylaxis in foot and ankle surgery

Background: The purpose of this prospective study was to determine whether the more frequently quoted procedure and patient specific risk factors have any impact in the implementation of venous thromboembolism (VTE) prophylaxis following foot and ankle surgery.

Methods: Two hundred and sixteen patients were included in the study. A variety of operative procedures was carried out with the common denominator being a below knee cast for at least 4 weeks and nonweightbearing for an average of 6 weeks in 130 patients. The remainder of the patients (88) had hallux surgery not requiring a cast and were allowed to weightbear. No patient received any form of thromboprophylaxis postoperatively. All patients were subjected to compression ultrasonography for deep vein thrombosis (DVT) between 2 and 6 weeks postoperatively.

Results: There was a 5.09% incidence of VTE (0.9% pulmonary embolism) overall. As no VTE (neither DVT nor pulmonary embolus) developed in the hallux subgroup, i.e. patients not requiring immobilization and were allowed to weightbear, the incidence of VTE in the cast/nonweightbearing group was 8.46%. The results are descriptive and only statistically analyzed where possible, as the sample size of the VTE group was small. There was no significant difference in number of risk factors and no association between gender in the VTE and non VTE groups. 90.9% of patients in the VTE group had a total risk factor score of 5 or more and 73.7% of patients in the non VTE group had a total risk factor score of 5 or more. The average timing to the diagnosis of VTE in this current study was 33.1 days.

Conclusions: In view of the unacceptable incidence of VTE and the average total risk factor score of 5 or more (for which thromboprophylaxis is recommended) in the majority of the patients, the authors feel that the routine use of thromboprophylaxis in foot and ankle surgery requiring nonweightbearing in combination with short leg cast immobilization, is warranted. This prophylaxis should continue until the patient regains adequate mobility either by weightbearing (in or out of the cast) or removal of cast immobilization (weightbearing or nonweightbearing), usually between 28 and 42 days.