Correlation Between VTE Risk and Venous Congestion in Microvascular Reconstruction of the Lower Extremity.

BACKGROUND Risk for VTE formation and the relationship to post-operative free flap venous congestion and flap failure has not been adequately evaluated in a trauma population. We aim to use the Caprini Risk Assessment Model (C-RAM) to evaluate the association between VTE risk and post-operative flap venous congestion following lower extremity free tissue transfer. METHODS A retrospective analysis was conducted of all patients who underwent lower extremity free flap reconstruction of traumatic defects at a single institution between 2007 and 2016. A Wilcoxon rank sum test was used for non-parametric analysis of aggregate C-RAM scores and flap outcomes. Flap venous congestion and failure rates as associated with the categorical variables underlying the C-RAM were further studied. Logistic regression was used to evaluate each of these outcomes and other flap-related covariates relative to the C-RAM categorical variables which had the greatest effect on our patient sample. RESULTS 112 patients underwent lower extremity free flap reconstruction. 109 free flaps were analyzed. 7 patients were excluded. The majority of patients were male (75.9%) and required reconstruction due to acute trauma (68.1% vs 31.9% for chronic wounds). There was no statistically significant association found between age, BMI, or timing of trauma with venous congestion, flap failure, or other flap related covariates. CONCLUSION In patients with significantly elevated C-RAM scores, there was no significant association between VTE risk and flap failure following free tissue reconstruction of lower extremities.