Venous malformations (VM) are the most common vascular anomaly in the lower extremity. VM can be classified as focal, multifocal or diffuse types. Intraarticular VM (IA-VM) of the knee portends morbidity. Association of lower extremity VM type with IA-VM is not well defined.To classify a large cohort of lower extremity nonsyndromic VM 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 VM, 26 (31%) were Bockenheimer and 59 (69%) localized subtypes. Pure VM had a significantly elevated risk of IA-VM (RR 2.34 95% 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]). 100% of genuine diffuse VM had IA-VM, 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 VM. Pure VM and the Bockenheimer diffuse VM subtype had the highest risk of IA-VM.