True degenerative aneurysms (including all three layers of the arterial wall) must be distinguished from false aneurysms or pseudoaneurysms . True degenerative aneurysms of the common femoral artery are relatively rare, with aneurysms of the superficial and deep femoral arteries being even less common. Femoral aneurysms are frequently asymptomatic and can be discovered incidentally as pulsatile masses or may present with localized pain or distal ischemia secondary to thromboembolic events. It is rare that a femoral aneurysm would rupture or bleed spontaneously. Once discovered, they should be evaluated with duplex ultrasound or contrast-enhanced CT scan with additional objective to evaluate for other concurrent aneurysms and the anatomic extent of the aneurysm. Contrast angiography and MRA can be used as adjunctive diagnostic tests to further provide information regarding the patency of outflow vessels if concern for thromboembolism exists.

All symptomatic femoral aneurysms regardless of etiology should be repaired. True aneurysms larger than 2.5 cm at presentation should be considered for repair; aneurysms less than 2.5 cm typically have a benign natural history and can be followed serially with duplex ultrasound. Open surgical repair for aneurysms isolated to the common femoral artery remains the gold standard of management with excellent early- and long-term results. Endovascular options are generally not recommended due to the flexion crease at the groin, which can subject endovascular prostheses to potential kinking, migration, and stent fatigue. Reconstruction depends on the extent of the aneurysm, the patency of the femoropopliteal segment, and the aneurysm patency. Type I femoral aneurysms (limited to the proximal common femoral artery) are often repaired with an interposition graft. Aneurysms that involve the origin of the deep femoral artery (type II) will require more complex reconstruction that involves revascularization of both the deep and superficial femoral arteries. Prosthetic grafts with 8–10 mm polyester or expanded polytetrafluoroethylene (ePTFE ) can be used for most cases, although if concern for infected or mycotic aneurysms exists reversed saphenous vein graft would be the conduit of choice. Exposure can be achieved through a vertical groin incision to allow for proximal control of the common femoral artery as well as control of the superficial femoral artery and deep femoral artery branches. For aneurysms of the deeper branches of the deep femoral artery, ligation may be used or endovascular techniques with coil embolization can be utilized. Treatment of aneurysms of the superficial femoral artery depends on location with open surgical techniques preferred with interposition grafting of the proximal superficial femoral artery. Alternatively, bypass in conjunction with proximal and distal ligation of the aneurysmal segment is another viable option. Endovascular stent grafts have also been reported in the mid to distal superficial femoral artery.

Individual institution results have shown a 5-year patency rate of up to 85 % for open surgical repair of common femoral artery aneurysms, with choice of conduit not affecting results. Deep and superficial femoral artery aneurysms are rarer and do not have long-term results reported. Endovascular repairs have been recently reported with satisfactory short-term patency rates, but long-term patency remains unknown. Lack of adequate distal outflow appears to be negative prognostic factor when determining long-term patency .

Popliteal artery aneurysms are uncommon, with an estimated incidence of 1 % in the general population [3]. They account for almost 70 % of lower extremity aneurysms [4] and are most commonly true degenerative aneurysms. They can be bilateral in up to 50 % of patients and can be associated with abdominal aortic aneurysm in 30–50 % [4, 5]. They are frequently asymptomatic at time of presentation, with 25–50 % of popliteal artery aneurysms found incidentally. They can also present with symptoms from local compression, thromboembolism or acute limb ischemia, and ischemic rest pain or rarely rupture (less than 2 %). Symptoms from compression usually occur when the aneurysm reaches a size greater than 3 cm and can cause posterior knee fullness, nerve-related pain with paresthesias and foot drop, and congestive venous swelling from associated deep venous thrombosis. Diagnostic modalities are often dependent on initial presentation and will include physical exam findings, duplex ultrasound, and contrast-enhanced CT scans or MRI, which may assist in procedural planning. Vascular ultrasound can be used to evaluate the size of aneurysm, presence of mural thrombus and velocities through the vessel, as well as evidence of leg perfusion with ankle-brachial indices. Contrast angiography alone is limited by showing only luminal flow (when compared to 3D modalities of CT and MRI), but can be useful in demonstrating distal outflow, especially in cases in which there is evidence of distal thromboembolism or when endovascular intervention is considered.

Popliteal artery aneurysms can present as a limb-threatening event, usually caused by thrombosis of the aneurysm with concomitant loss of runoff vessels. From 40 to 50 % of patients present in this manner, an overall have the worst prognosis in respect to limb salvage. If patients present with symptomatic popliteal artery aneurysm or evidence of extremity ischemia, they should undergo urgent repair. In asymptomatic patients with aneurysms greater than 2 cm, elective repair is often recommended. The choice of repair is often dependent on patient-specific issues such as medical comorbidities, functional status, and life expectancy. Elective open repair can be accomplished via two different exposures: medial and posterior. The medial approach can be performed with non-tunneled saphenous vein graft with ligation of the intervening aneurysmal segment of artery. Although the medial approach allows greater ease at greater saphenous vein harvest, it permits the genicular branches to continue to feed the aneurysm sac and can lead to endotension and increased aneurysm size in few cases. The posterior approach with the patient in the prone position allows the surgeon to perform open repair of the aneurysm with ligation of geniculate branches—with complete aneurysm excision, ligation of all branches, and relief of compression symptoms by larger aneurysms. Vein harvest can be more challenging with the patient in the prone position, and the tibial nerve is at risk with a posterior approach.

Endovascular repair is an option for patient with suitable anatomy and adequate outflow vessels and may have a major role in patients with major medical comorbidities. As with any endograft, adequate proximal and distal seal zones are required with freedom from thrombus, excessive calcifications, or tortuosity. CT angiography is usually performed to assist in pre-procedural planning to determine diameter, length, and number of stent grafts necessary for the procedure. Access can be performed percutaneously in patients with normal-sized proximal and distal landing zones , but in patients with arteriomegaly and larger diameter landing zones requiring larger diameter devices, open arterial exposure may be required. When planning endovascular intervention that crosses the knee joint, proper stent graft overlapping can minimize graft slippage and kinking. After repair, patients should remain on dual antiplatelet therapy (clopidogrel and aspirin) with close follow-up with duplex ultrasonography or CT angiogram usually recommended. In patients with acute ischemia from thrombosis or distal embolism, mechanical thrombectomy and catheter-directed thrombolysis are recommended to restore distal runoff and are more likely to be successful with recent thromboembolic events. If there is severe limb ischemia at the time of diagnosis, then endovascular therapy would be contraindicated due to the increased amount of time required to establish distal perfusion, and surgical mechanical thrombectomy would instead be indicated.

Overall 30-day amputation rates are reported as 14.1 % with approximately 20 % of those amputations performed as the primary procedure without attempt at thrombectomy , thrombolysis, or surgical revascularization . Ruptured popliteal aneurysms tend to have higher risk of amputation, with rates as high as 50–75 %. Open operative therapy remains the gold standard for elective repair of popliteal artery aneurysms with long-term limb salvage rates of up to 90 % at 10 years for asymptomatic aneurysms. Success rates decrease significantly with symptomatic popliteal aneurysms, in particular those with acute limb ischemia. Endovascular repair is becoming a more popular option, especially in patients with significant comorbidities, and success rates are dependent on number of patent outflow vessels, with at least two vessels necessary for favorable short-term outcomes. Although patency rates tend to be similar to open repair, there is an increased incidence of interventions required to maintain patency .