Patient: Male, 54-year-old Final Diagnosis: Femoral fracture due to gigantic pseudoaneurysm secondary to the rupture of a previously ligated and bypassed popliteal artery aneurysm Symptoms: Swelling and pain Clinical Procedure: — Specialty: Orthopedics and Traumatology • Surgery Objective: Unusual clinical course Background: This case report describes a giant pseudoaneurysm that grew in size during the years following surgical treatment of a popliteal artery aneurysm, eventually causing a femoral fracture. Bone fractures secondary to vascular injuries are rarely described in the literature. Case Report: A 54-year-old man underwent surgical ligation and bypass for left popliteal artery aneurysm. Seven years later, he suffered a left distal femur pathologic fracture surrounded by a giant soft-tissue mass. The patient came to us with a diagnostic hypothesis of angiosarcoma from another hospital at imaging evaluation. After computed tomography angiography (CTA) and angio-magnetic resonance imaging (MRI), we made a diagnosis of femoral pathologic fracture caused by a giant pseudoaneurysm of a treated popliteal artery aneurysm refilled by an aberrant anterior tibial artery (IIA2, Kim classification). We performed excision of the mass and open reduction and internal fixation, with anatomic plate, of the fracture. Fracture healing and good functional outcome were observed at follow-up. Conclusions: A possible complication of surgical treatment of popliteal artery aneurysms is refilling of the excluded aneurysm due to collateral blood flow or, such as in the present case, aberrant vessels. Therefore, the knowledge of anatomical variants of the vessels is important in surgery. Follow-up evaluation after surgery is advisable and a growing mass should be further investigated with an angio-CT scan. In case of a non-pulsating soft-tissue mass causing pathologic bone fracture, a biopsy is mandatory to exclude malignancy.