Classification of lower extremity venous malformations and risk of knee involvement: A retrospective cohort study

Abstract

Venous malformation (VM) is the most common vascular anomaly in the lower extremity. VMs can be classified as focal, multifocal, or diffuse types. Intraarticular VM (IA-VM) of the knee portends morbidity. Association of the lower extremity VM type with IA-VM is not well defined. To classify a large cohort of lower extremity, nonsyndromic VMs by type and determine associations with IA-VM. Retrospective cohort study. We assessed 156 patients with nonsyndromic, lower extremity VM; 71 (46%) were focal and 85 (54%) were diffuse type VM, and 97 (62%) were IA-VM. Of diffuse VMs, 26 (31%) were Bockenheimer and 59 (69%) were localized subtypes. Pure VM had a significantly elevated risk of IA-VM (relative risk [RR], 2.34; 95% confidence interval [CI], 1.42-3.89). IA-VM was more common in diffuse (73%) versus focal (49%) types. Risk of IA-VM in diffuse type VM was significantly elevated (RR, 1.48; 95% CI, 1.13-1.94). One hundred percent of diffuse Bockenheimer type VM had IA-VM, and this subtype had the highest risk (RR, 1.83; 95% CI, 1.56-2.14) of IA-VM. Retrospective, single-institution study. Intraarticular involvement of the knee should be considered in all lower extremity VMs. Pure VM and the Bockenheimer diffuse VM subtype had the highest risk of IA-VM.