Lower limb traumatic pseudoaneurysm and arteriovenous fistula

Case contributed by Dr Eid Kakish

Presentation

Victim of high-energy road traffic accident, sustaining a left femoral shaft fracture with multiple previous orthopedic procedures. Intra-operative arterial bleeder.

Patient Data

Age: 20 years
Gender: Male

Complex comminuted angulated non-united fracture involving the mid-shaft of the left femur with extensive surrounding callus formation and heterotopic ossification. A metallic external fixation device is seen in situ, resulting in marked beam hardening artifact at the region of interest. Global atrophic changes and fatty replacement are seen involving the muscles of the left thigh.

Tiny contrast filled saccular outpouching is seen communicating with the anterolateral wall of the distal left superficial femoral artery, suggestive of a small left distal femoral pseudoaneurysm.

The distal segment of the left superficial femoral vein appears dilated and demonstrates early luminal opacification on the arterial phase, it appears to be communicating with the adjacent distal left superficial femoral artery via a short neck. Findings are in keeping with an arteriovenous fistula.

Incidental lateral duplication of the left superficial femoral vein.

Sagittal: yellow circle around the concomitant post-traumatic AV fistula and pseudoaneurysm 

Axial: red arrow pointing to the incidental duplication of the left SFV.

Case Discussion

Despite the extensive beam hardening artifact at the region of interest, concomitant left superficial femoral artery pseudoaneurysm and AV fistula are beautifully demonstrated in this case, likely secondary to patient's previous trauma. However, this patient has undergone multiple orthopedic procedures, which may as well be a contributing factor in the development of these vascular lesions. 

Most cases of SFV duplication arise at the level of the adductor canal or just slightly more superiorly in the mid-thigh, with equal chances of lateral or medial duplication. A study by Quinlan et al. concluded that only 4% of the duplicated vessels were at a comparable caliber to the native vessel. Knowledge of such variations is imperative to avoid missing potential thromboembolic events in duplicated lower limb deep veins. 

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