Surgical and endovascular repair of popliteal artery aneurysm

INTRODUCTION — Popliteal artery aneurysm (figure 1) presents in a variety of ways. Many patients are asymptomatic, while others have symptoms referable to the aneurysm such as pain with ambulation (claudication) or acute limb ischemia due to aneurysm thrombosis or distal embolization [1-3]. When popliteal aneurysm repair is indicated, an open surgical or endovascular approach can be used. The choice of repair depends upon the clinical presentation, anatomic factors, and patient comorbidities.

The approach to popliteal artery aneurysm repair, perioperative care, complications of repair, and surgical outcomes will be reviewed here. The diagnosis and nonsurgical management of popliteal artery aneurysm are discussed elsewhere. (See "Popliteal artery aneurysm".)

INDICATIONS — Surgical or endovascular repair for popliteal aneurysms is indicated under the following circumstances:

●Symptomatic (eg, acute limb ischemia, disabling claudication) popliteal aneurysm of any size

●Selected asymptomatic popliteal aneurysm (patent) depending upon diameter and presence of thrombus

These management of popliteal artery aneurysm (algorithm 1) is discussed in more detail elsewhere. (See "Popliteal artery aneurysm", section on 'Symptomatic patients' and "Popliteal artery aneurysm", section on 'Asymptomatic patients'.)

Contraindications — Contraindications (absolute or relative) to repair of popliteal artery aneurysm include asymptomatic patients with completely thrombosed popliteal artery aneurysm, nonambulatory patients, and those with acutely thrombosed aneurysms with persistently poor runoff in spite of thrombolysis.

Asymptomatic patients with a completely thrombosed popliteal aneurysm are not repaired, regardless of the diameter of the popliteal artery aneurysm. These patients can be managed in a manner similar to patients with lower extremity peripheral artery disease if symptoms (eg, claudication) develop, with surgical bypass reserved only for disabling symptoms or critical limb ischemia. (See "Popliteal artery aneurysm", section on 'Asymptomatic patients' and "Popliteal artery aneurysm", section on 'Chronic ischemia'.)

Although most patients with appropriate indications for repair are candidates for open or endovascular repair, patients who are nonambulatory and those with prohibitive risks for intervention should be treated conservatively. (See "Popliteal artery aneurysm", section on 'When to and not to intervene'.)

Patients with acutely thrombosed popliteal aneurysms who have persistently poor (or no) runoff through the tibial vessels despite thrombolysis (preoperative or intraoperative) may be poor candidates for popliteal artery repair and may require subsequent amputation. In one retrospective review, poor runoff (as measured by runoff score [4]) was one of only two variables associated with loss of graft patency; ongoing smoking was the other [5]. However, in this study, nearly one half of the grafts used were synthetic. In another review in which only vein grafts were used, the outcome did not correlate with runoff anatomy [6]. Thus, in patients with acutely thrombosed popliteal aneurysms, poor runoff following thrombolysis may be a relative contraindication to popliteal artery aneurysm repair if a suitable vein conduit is not available. (See "Popliteal artery aneurysm", section on 'Role of antithrombotic therapy and thrombolysis' and 'Outcomes' below.)

ANATOMY OF THE POPLITEAL FOSSA — The popliteal fossa is a diamond-shaped space located posterior to the knee joint. The superior and inferior margins are defined by the supracondylar line of the femur and soleal line of the tibia, respectively. From a posterior view (figure 2), the space is bounded above the knee by the biceps femoris tendon, which inserts laterally, and semimembranous tendon, which inserts medially. Below the knee, the medial and lateral margins are formed by the insertions of the medial and lateral heads of the gastrocnemius muscle.

The popliteal fossa contains the popliteal artery, popliteal veins, and tibial nerve. The popliteal artery is the continuation of the superficial femoral artery. Anatomic landmarks demarcating the popliteal artery include the tendinous insertion of the adductor magnus muscle in the distal femur superiorly, and the bifurcation of the popliteal artery into the anterior tibial artery and tibioperoneal trunk at the level of the tibial tuberosity inferiorly. Anatomic variations of the distal popliteal artery include a high origin of the anterior tibial artery; trifurcation of the vessel into the anterior tibial, peroneal, and posterior tibial arteries (ie, no tibioperoneal trunk); and a hypoplastic or aplastic posterior tibial artery [7].

Collateral flow around the knee is critical in maintaining lower extremity perfusion when a popliteal aneurysm thromboses (figure 3). Collateral pathways are provided by the superior and inferior genicular (medial and lateral), anterior recurrent tibial, and descending genicular arteries.

The popliteal vein is typically paired, traveling adjacent the popliteal artery with numerous interconnections (venae comitantes); one of the veins usually predominates in size. The popliteal vein originates at the confluence of the anterior and posterior tibial veins; the peroneal veins empty into it more superiorly. The popliteal vein becomes the femoral vein at the adductor canal.

The tibial nerve is derived from the sciatic nerve. In the popliteal fossa, the tibial nerve gives off muscular branches (ie, gastrocnemius, popliteus, soleus, plantaris), and a sensory branch (ie, soleal nerve) that innervates the lateral aspect of the foot. The tibial nerve traverses distally in the leg along the surface of the soleus muscle supplying the muscles that plantar flex the foot.

PREOPERATIVE EVALUATION — Prior to open surgical or endovascular repair of the popliteal artery, the patient's clinical condition; medical comorbidities; and vascular anatomy, including the presence of other large vessel aneurysms (eg, abdominal aortic aneurysm, iliac aneurysm); are evaluated. These factors influence the timing of repair and the choice between open surgical or endovascular repair of the popliteal aneurysm.

Clinical assessment — Popliteal aneurysm is often asymptomatic, but many patients have symptoms referable to the aneurysm, ranging from pain with walking (ie, intermittent claudication) to symptoms of acute limb ischemia due to acute aneurysm thrombosis, or distal embolization [1,2]. (See "Popliteal artery aneurysm", section on 'Clinical presentation' and "Clinical features and diagnosis of acute lower extremity ischemia", section on 'Clinical presentations'.)

Asymptomatic patients and those with viable limbs that are not threatened (table 1) can undergo outpatient preoperative evaluation and repair. For patients who present acutely with a threatened extremity, urgent or emergent inpatient evaluation and repair are undertaken. In patients with acute thrombosis, an intravenous systemic anticoagulation should be initiated to limit the extension of thrombus. (See "Popliteal artery aneurysm", section on 'Role of antithrombotic therapy and thrombolysis'.)

Limb salvage rates following repair of popliteal artery aneurysm (open surgical or endovascular) correlate with an increasing number of patent tibial outflow vessels [1,8,9]. To improve outflow, thrombolytic therapy (catheter-directed or intraoperative) or thromboembolectomy is routinely performed. Catheter-directed thrombolysis is less appropriate for immediately threatened extremities because length of time needed to dissolve the clot is usually prolonged (12 to 24 hours). (See 'Open versus endovascular repair' below.)

Anatomic assessment — Imaging the patient's vascular anatomy is necessary prior to repair. Arterial imaging with computed tomography angiography, magnetic resonance angiography, or invasive arteriography assesses the suitability for endovascular repair, evaluates proximal and distal arterial patency, and may identify coexisting aneurysm. Although duplex ultrasound may identify the presence of an aneurysm, it does not show sufficient detail to plan a repair but is essential for mapping the venous system to identify suitable veins to serve as a bypass conduit. (See "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Duplex ultrasound' and "Advanced vascular imaging for lower extremity peripheral artery disease".)

Suitability for endovascular repair — The tortuosity and extent of aneurysm and the presence of adequate stent-graft landing zones should be carefully evaluated. At least 15 to 20 mm of normal artery should be available proximal and distal to the aneurysm to obtain adequate stent-graft fixation [10]. Clinicians should review the instruction for use (IFU) for the particular endovascular device being used. (See 'Endovascular aneurysm repair' below.)

The aneurysm may be limited to the popliteal fossa or extend proximally to the distal superficial femoral artery or distally to popliteal artery bifurcation. Focal aneurysms more typically have normal appearing proximal and distal popliteal artery segments, but popliteal artery aneurysms are frequently associated with diffuse arteriomegaly. Focal aneurysms are amenable to a short bypass or placement of a single stent-graft. Angulation may be present (most commonly at the adductor canal) if the aneurysm extends proximally into the superficial femoral artery. Although mild angulation may straighten with a stent, severe angulation (>45 degrees) is likely to cause future kinking of the stent, and open surgical repair may be more appropriate.

Proximal and distal circulation — Low flow due to proximal stenosis or occlusion and/or decreased outflow from a stenotic/thrombosed popliteal artery or occluded tibial vessels decreases patency rates of open surgical and endovascular repair [9,11,12]. Restoration of arterial inflow with stenting or bypass and/or restoration of arterial outflow with thrombectomy/thrombolysis (in the acute setting) should be performed prior to, or at the same setting as, popliteal aneurysm repair [2,13]. (See "Management of chronic limb-threatening ischemia".)

Atherosclerotic peripheral artery disease is present in a significant proportion of patients with popliteal artery aneurysm and should be managed concomitant with popliteal artery aneurysm to improve the outcomes of repair. In one retrospective review, 40 percent of patients had severe atherosclerosis of the femoral artery. Atherosclerosis-related occlusion of the superficial femoral artery was present in 17 percent [5].

Tibial vessel occlusion in patients with popliteal artery aneurysm is most likely due to thromboembolism. Catheter-directed or direct intraoperative thrombolytic therapy may restore patency of the anterior tibial, posterior tibial, or peroneal arteries in patients presenting with acute ischemia, thus improving the likelihood of a successful popliteal artery aneurysm repair. Patients with acutely thrombosed popliteal artery aneurysms who have poor runoff in spite of thrombolysis may be poor candidates for popliteal artery aneurysm repair and subsequently require amputation [5]. (See "Popliteal artery aneurysm", section on 'Role of antithrombotic therapy and thrombolysis' and 'Contraindications' above.)

Coexistent aneurysms — Popliteal aneurysm is a marker for a large artery aneurysm diathesis. An estimated 75 percent of patients with a popliteal aneurysm will have another aneurysm at a separate site (contralateral popliteal artery, femoral arteries, abdominal aorta, iliac arteries) [3]. (See "Popliteal artery aneurysm", section on 'Diagnosis'.)

The presence of other aneurysms (aortic, iliac, or femoral) influences the timing and nature of the popliteal aneurysm repair. Generally, for asymptomatic patients, aneurysms proximal to the popliteal aneurysm should be managed first, if indicated, as these have a potential to embolize distally and may occlude the popliteal bypass or stent. (See "Iliac artery aneurysm" and "Femoral artery aneurysm".)

Availability of conduit — Long-term patency rates are higher when autogenous vein rather than prosthetic graft is used for lower extremity bypass below the knee [5,14], and thus, the availability of vein may determine the approach to popliteal aneurysm repair. The diameter, length, and patency of the great saphenous vein ipsilateral and contralateral to the popliteal aneurysm should be evaluated. The ipsilateral saphenous vein may be preferred in patients with bilateral aneurysms and in those with more extensive popliteal aneurysms (ie, requiring a long bypass). The femoral vein is an acceptable conduit if great saphenous vein is not available bilaterally and the patient is not a candidate for endovascular repair. (See "Lower extremity surgical bypass techniques", section on 'Vascular conduits'.)

Medical risk assessment — The risk factors for popliteal artery aneurysm are similar to those of other major vascular aneurysms (ie, abdominal aortic, iliac, and femoral aneurysms) and include smoking, hypertension, hyperlipidemia, cerebrovascular disease, and coronary heart disease, among others [3]. However, in contrast to atherosclerotic occlusive disease, diabetes mellitus is associated with a decreased risk for aneurysmal disease. (See "Popliteal artery aneurysm", section on 'Risk factors'.)

Because of these associations, a complete medical history with particular attention to risk factors for cardiovascular disease should be obtained since comorbidities may impact the choice of repair. (See "Evaluation of cardiac risk prior to noncardiac surgery" and "Management of cardiac risk for noncardiac surgery".)

Prior to elective repair, the patient should be referred to a smoking cessation program. Active smoking at the time of surgery is associated with an increased risk for pulmonary complications and is an independent risk factor for bypass graft failure. (See "Popliteal artery aneurysm", section on 'Management' and "Strategies to reduce postoperative pulmonary complications in adults", section on 'Smoking cessation'.)

OPEN VERSUS ENDOVASCULAR REPAIR — The goal of popliteal artery aneurysm repair is to eliminate the aneurysm from the circulation and maintain perfusion to the extremity. Open surgical bypass and endovascular stent-grafting each accomplish these goals. Whether an open surgical or endovascular approach is preferred is the subject of much debate [15]. Clinical practice varies widely [16]. Limited data are available comparing popliteal artery aneurysm repair techniques, and major society guidelines provide no guidance in choosing between open surgical versus endovascular repair [2,17]. We advocate an individualized approach taking into account the clinical presentation (elective versus emergent), the degree of limb ischemia, the patient's medical comorbidities, and their vascular anatomy (suitability for endograft, status of the proximal/distal circulation, coexistent aneurysm, availability of vein conduit) (algorithm 2) [18,19].

The benefit of endovascular stent-grafting may be the greatest in patients with indications for elective repair who have a high perioperative risk for surgery. We suggest endovascular repair in these patients provided the popliteal segment is suitable for endograft placement (see 'Suitability for endovascular repair' above). Compared with endovascular repair, open repair is associated with increased mortality, particularly in patients with medical comorbidities, although some have argued that the outcomes of studies comparing open and endovascular repair may be biased since open repair of popliteal artery aneurysm is more commonly used for managing patients with acute popliteal aneurysm thrombosis. Nevertheless, we feel that avoiding the risks associated with anesthesia and potentially the need for transfusion in high-risk patients is highly desirable. (See 'Outcomes' below.)

Whether patients with indications for elective repair who are not at high risk for open surgery should undergo open surgical or endovascular repair is more controversial [20-23]. For these patients, we suggest open surgical repair, provided the patient has adequate vein conduit. If adequate vein is not available, a short segment of prosthetic graft is an alternative, particularly when placed with the patient in the prone position. An endovascular approach may also be an acceptable alternative if appropriate proximal and distal landing zones are present in the popliteal artery. Open surgical repair is the accepted standard and is a durable procedure that has been shown in retrospective studies to be associated with low perioperative morbidity and mortality [8,15,19,21,24,25]. A database review from the Vascular Quality Initiative suggested better outcomes for elective open compared with endovascular repair (asymptomatic patients) [26]; however, some [27], but not all, retrospective reviews have found no significant differences [28]. Early graft failure is uncommon with open repair, and long-term rates for limb loss are low [28,29]. Systematic reviews have identified one randomized trial comparing open surgical and endovascular repair of popliteal aneurysms (not acutely thrombosed) [18,21,28,30-32]. In this trial, although there were no significant differences in the overall patency of popliteal bypass grafts compared with endovascular stent-grafts, endovascular repair had a significantly increased risk of early (30 day) reintervention (odds ratio [OR] 18.8, 95% CI 1.4-245.9) and a trend toward early (30 day) graft thrombosis. The main advantage of endovascular repair was a shorter length of hospital stay (weighted mean difference -3.9 days, 95% CI -4.3 to -3.4). An update of this randomized trial assessed longer-term outcomes in 27 open and 21 endovascular repairs [33]. Primary patency rates in patients undergoing open popliteal aneurysm repair compared with endovascular repair were not significantly different at 12 or 72 month follow-up. Secondary patency rates at 72 months were 88 and 86 percent for open and endovascular repair, respectively. The latest systematic review, including the randomized trial and 13 other observational studies, evaluated the outcomes of 4880 cases (1210 endovascular, 3915 open surgical) [32]. Primary patency at one year was significantly better for open repair (88.3 versus 71.2 percent at one year [11 studies], and 79.4 versus 68.2 percent at three years [6 studies]), but there were no differences for secondary patency rates (92.3 versus 86.3 percent at one year [9 studies], and 86.6 versus 80 percent at three years [5 studies]). Open repair was more likely to be performed in younger patients and those with worse tibial runoff compared with those who underwent endovascular repair. This meta-analysis found that while endovascular repair had a lower wound complication rate and shorter length of stay, it comes at the cost of inferior primary patency, but not secondary patency out to three years.

Other factors need to be taken into consideration in patients undergoing popliteal artery aneurysm repair for emergent indications (acute thrombosis, rupture). Thrombolytic therapy is appropriate for thrombosed popliteal artery aneurysms causing acute limb ischemia to improve outflow, provided the limb is not immediately threatened. Patients with an immediately threatened limb are treated with an open surgical approach that includes thromboembolectomy and intraoperative infusion of lytic agents rather than using a percutaneous method of thrombolysis due to the prolonged time needed to lyse a heavy burden of thrombus that could further compromise the extremity [9,34,35]. (See "Popliteal artery aneurysm", section on 'Role of antithrombotic therapy and thrombolysis' and 'Outcomes' below and "Embolism to the lower extremities", section on 'Immediately threatened extremity'.)

In patients for whom adequate distal runoff (two or three vessel runoff) is restored following percutaneous thrombolytic therapy, a decision for open versus endovascular repair can be made based upon an assessment of perioperative surgical risk and anatomic factors, as discussed above for elective repair. If distal runoff is not adequately restored following thrombolysis, we suggest an aggressive attempt at surgical revascularization provided that a distal target for revascularization is identified and the patient has adequate vein conduit.

Ruptured popliteal artery aneurysms are uncommon (3 percent in one study [19]) and may be best managed using a hybrid approach, with endovascular techniques for initial control of hemorrhage and/or repair of the vessel, and open techniques to manage the hematoma, as needed [36]. However, ruptured popliteal aneurysms may be associated with infection, which necessitates complete excision of the aneurysm and ideally autogenous reconstruction, although an endovascular approach has also been used for high-risk patients [37]. (See "Overview of infected (mycotic) arterial aneurysm", section on 'Lower extremity'.)

PREPARATION

Anticoagulation — For patients with acute thrombotic occlusion or distal embolization, systemic anticoagulation and/or thrombolytic agents will have been instituted. (See "Popliteal artery aneurysm", section on 'Role of antithrombotic therapy and thrombolysis' and "Intra-arterial thrombolytic therapy for the management of acute limb ischemia".)

Once a decision to proceed to open surgery to repair popliteal artery aneurysm has been made, the thrombolytic agent should be discontinued to minimize intraoperative bleeding. Systemic anticoagulation should be resumed after the thrombolytic agent has been discontinued and maintained up to the time of the operation to decrease the risk for re-thrombosis.

Prophylactic antibiotics — Prophylactic antibiotics are recommended within one hour of the skin incision for patients undergoing vascular surgical procedures that involve a groin incision or the use of prosthetic material [38]. Antibiotic choices are given in the tables (table 2 and table 3). (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults".)

DVT prophylaxis — Patients undergoing major vascular procedures are at moderate to high risk for developing deep vein thrombosis (DVT; older age, bed rest postoperatively, major surgery >45 minutes) (table 4) and should receive prophylaxis if not already receiving systemic anticoagulation. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

For patients who present with DVT as a manifestation of popliteal aneurysm, we treat the DVT according to standard protocols and delay elective open repair. (See "Overview of the treatment of proximal and distal lower extremity deep vein thrombosis (DVT)".)

Patient counseling — Although the risk of procedure-related complications is overall low, patients undergoing elective popliteal artery aneurysm repair are counseled regarding their individual risk for morbidity/mortality compared with the benefits of popliteal artery aneurysm repair (ie, lowered risk of future limb-threatening ischemia). (See "Popliteal artery aneurysm".)

For patients undergoing endovascular repair, the most common complications are related to the percutaneous access site, but the possibility of stent-graft thrombosis (early or late) or device-related complications such as stent migration or kinking requiring reintervention or conversion to open surgical bypass should be discussed. (See 'Stent-graft complications' below.)

For open surgery, complications include bleeding requiring transfusion, infection, and graft thrombosis. The potential need for further surgery to revise or manage graft infection or thrombosis should be conveyed. Graft thrombosis and graft infection increase the risk for future amputation. (See 'Surgical complications' below.)

Patients requiring emergent popliteal aneurysm repair due to acute popliteal aneurysm thrombosis have a greater risk for complications, including graft thrombosis, and are informed of the high risk of limb loss. (See 'Outcomes' below.)

SURGICAL BYPASS — Two approaches are described for open repair of popliteal artery aneurysm, a medial approach involving exclusion of the aneurysm and bypass, and a posterior approach, which involves a direct in-line repair with an interposition graft. There are no randomized data to support one approach over the other. In a systematic review of observational studies involving 1427 repairs (338 posterior, 1089 medial), although primary patency rates favored a posterior approach, there were no significant differences between the approaches for long-term patency, amputation rates, or complications [39].

In one retrospective review of 571 patients, 87 percent were managed with a medial approach and 8 percent with a posterior approach [40]. In another review of 234 open surgical repairs, a posterior approach was used in 71 patients, and in the remaining 163, a medial approach was preferred [19]. Aneurysmal ligation and bypass grafting was used in 122 interventions, aneurysmectomy with graft interposition was used in 108, and four patients underwent aneurysmectomy with an end-to-end anastomosis. An autologous vein was used in 49 interventions, and a prosthetic graft was used in 181. Primary vein graft patency rates were not significantly different between the medial and posterior approach (85 versus 90 percent). (See 'Anatomic assessment' above and 'Open versus endovascular repair' above.)

Patency rates notwithstanding, anatomic considerations may indicate a preference for one approach over the other [40-43]. When an initial surgical approach is indicated in patients with acutely thrombosed popliteal aneurysms (ie, threatened limb), or there is evidence of embolization of the tibial vessels, we suggest a medial approach, which facilitates thromboembolectomy or intraoperative thrombolytic therapy. Graft patency is improved when the burden of thrombus is minimized [1,8,9]. It may be more difficult to effectively clear thrombus using a posterior approach. On the other hand, for patients with focal aneurysms confined to the popliteal fossa, we suggest a posterior approach, which minimizes the length of the graft required (see 'In-line reconstruction' below). For practitioners who are not familiar with the posterior approach, the medial approach is an acceptable alternative.

Aneurysm exclusion and bypass — With the medial approach, the popliteal artery aneurysm is left in situ and bypassed using a segment of saphenous vein (figure 4) [44]. The popliteal artery is ligated proximal and distal to the aneurysm to exclude it from the circulation [45]. Ligation of the popliteal artery is performed close to the aneurysm to minimize the loss of collateral vessels [46]. (See 'Anatomy of the popliteal fossa' above.)

The conduit of choice for lower extremity bypass is ipsilateral great saphenous vein (reversed or nonreversed). In a study of the Vascunet Registry, vein graft was used in 87 percent of patients [16]. Below-the-knee prosthetic (polytetrafluoroethylene [PTFE]) grafts have an increased risk of thrombosis and are avoided, whenever possible, for the repair of popliteal artery aneurysm. In one single institution review, primary patency at 24 months for saphenous vein was 95 percent compared with 79 percent for PTFE [17]. (See 'Bypass patency' below and "Lower extremity surgical bypass techniques".)

The vein graft can be positioned adjacent the popliteal artery (ie, anatomic), or tunneled subcutaneously along the medial aspect of the knee, depending upon the extent of the bypass, patient anatomy, and operator preference. Anatomic placement allows a straighter graft with less potential for kinking around the knee and may be more suitable for patients with muscular legs; however, the popliteal graft segment may be more difficult to appreciate on ultrasound surveillance. (See 'Graft surveillance' below.)

Extensive aneurysmal degeneration or atherosclerotic disease that affects the superficial femoral artery proximally or popliteal artery distally (ie, at the origin of the anterior tibial artery) necessitates originating a bypass graft from the common femoral artery or extending the graft distally to one of the tibial vessels, respectively. Aggressive distal bypass to the tibial vessels may be important for optimizing outcomes. In a retrospective review of 51 popliteal aneurysm repairs (37 elective, 14 emergent), overall primary patency rates at one-year and five-year follow-up were 96 and 85 percent, and secondary patency rates were 100 and 97 percent, respectively [47]. In this study, the percentage of patients who had a distal infrapopliteal target for lower extremity bypass was particularly high at 57 percent. However, no significant differences in primary patency were found for popliteal versus more distal bypass targets (84 versus 87 percent at five years).

In-line reconstruction — In-line reconstruction using a posterior approach may be preferred if the aneurysm is focal and confined to the popliteal fossa (figure 5), especially if the aneurysm is large and compressing adjacent structures [48,49]. However, this approach limits proximal vascular control, and embolectomy may be incomplete owing to an inability to direct the catheter distally into the individual tibial vessels. As such, most surgeons would not approach a thrombosed popliteal aneurysm posteriorly in the acute setting or if outflow is compromised.

With the posterior approach, a vein or prosthetic graft is used to reconstruct the popliteal artery. In a retrospective review of 571 patients, 45 of whom were managed with a posterior approach, vein graft and PTFE had similar one-year patency rates (85 and 81 percent, respectively) [40]. A "lazy" S-shaped incision is made over the popliteal fossa to minimize problems with scar contracture. After gaining vascular control, the popliteal artery is opened and the graft sutured to normal artery proximally and distally. Upon completion of the repair, the aneurysm sac is closed over the graft, provided enough arterial wall remains (similar to other aneurysm repairs). (See 'Outcomes' below.)

Surgical complications — Complications following elective open repair of popliteal aneurysms are uncommon. The most common postoperative problems involve the surgical wound, occurring in about 5 percent of cases [8]. Both local and systemic complications are greater in patients undergoing open repair of popliteal aneurysms for acute ischemia [8,24]. Early graft failure is uncommon. Complications of lower extremity bypass grafting are discussed separately. (See "Lower extremity surgical bypass techniques", section on 'Complications'.)

Graft patency rates depend upon the clinical situation leading to popliteal aneurysm repair, the status of the tibial outflow, and the type of conduit used. (See 'Outcomes' below.)

Complications that are unique to lower extremity bypass for popliteal artery aneurysm include late expansion of the residual aneurysm sac, aneurysm extension, and vein graft aneurysms.

●Late expansion of aneurysm sac – In spite of popliteal artery exclusion (ligation proximal and distal to the aneurysm at the time of popliteal artery bypass), aneurysm sac expansion occurs in up to 30 percent of patients due to persistent backflow from one or more of the geniculate vessels [45,50-55]. This complication usually occurs later in the postoperative course. In one retrospective review, perfusion of the aneurysm sac was identified at a median of six years after primary repair (range 1 to 20 years) [56]. Rupture of the residual popliteal aneurysm has been reported. If the residual sac continues to expand or the patient becomes symptomatic, the vessel(s) providing flow into the excluded aneurysm need(s) to be identified and ligated. This is usually accomplished using a posterior approach. The aneurysm sac is identified and opened, and the branches are ligated from within the sac.

Because of the nature of the open posterior approach, in-line reconstruction is associated with a much lower risk of postoperative sac expansion compared with the medial approach. In one retrospective review of 571 patients, the risk of expansion following posterior repair was 8 percent compared with 33 percent for the medial approach [40].

●Aneurysm extension/vein graft aneurysm – Aneurysmal degeneration of the arterial wall may continue following aneurysm repair. Further aneurysmal expansion of the proximal and/or distal popliteal artery has the same risks for thrombosis or embolization as the original aneurysm. Lifelong follow-up is important to identify and treat the ongoing disease process [57,58]. (See 'Graft surveillance' below.)

●Vein graft aneurysm – Vein bypass grafts used in patients treated for aneurysmal disease may be more prone to aneurysmal degeneration [57,59]. Vein graft aneurysms are more common after the repair of popliteal artery aneurysm compared with vein bypass grafting for atherosclerotic occlusive disease. In one study of 138 patients, 4 percent of patients with popliteal artery aneurysms managed with vein bypass grafts developed a vein graft aneurysm. (See 'Graft surveillance' below.)

ENDOVASCULAR ANEURYSM REPAIR — Focal popliteal aneurysms that do not extend into the distal popliteal artery are the most suitable for endovascular repair. More aggressive uses of endovascular stent-grafts include multiple stents for the repair of more extensive aneurysms that involve the superficial femoral artery, and stenting of ruptured popliteal artery aneurysm [36].

Early stent-grafts for the repair of popliteal artery aneurysm were homemade and fashioned from balloon-expandable stents attached to a 6 mm polytetrafluoroethylene (PTFE) graft, and on occasion, this type of graft may still be used [60]. Commercially available stent-grafts are composed of a self-expanding metal (eg, nitinol) framework covered with fabric. There are no randomized trials to guide specific device selection.

Stent-graft placement — Stent-grafts are placed percutaneously in an interventional suite or an appropriately equipped operating room, or if the need dictates, via a common femoral artery cut-down in the operating room. Fluoroscopy is used to guide stent-graft positioning.

Common femoral artery access can be obtained on the same side of the aneurysm (antegrade puncture), navigating the guidewires and catheters down the leg to the aneurysm, or contralateral to the aneurysm (retrograde puncture), navigating the guidewire and catheters up and over the aortic bifurcation and down to the aneurysm [61].

Once femoral access is achieved, an arteriogram is performed to evaluate the vasculature proximal and distal to the aneurysm. Patients who have evidence of prior embolization may benefit from thrombolytic therapy. Inadequate restoration of flow in continuity with the popliteal artery precludes placement of a stent-graft. These patients will require bypass to one of the tibial vessels. (See 'Surgical bypass' above.)

A soft guidewire is advanced through the popliteal aneurysm into one of the tibial vessels. The initial wire is replaced with a catheter through which a stiffer wire is placed. An adequate diameter and longer sheath is placed to protect the stent-graft as it is passed to the aneurysm site. The device is advanced over the stiff wire and additional imaging performed to ensure accurate placement of the device. The stent-graft should overlap the proximal and distal normal artery by at least 1 cm (figure 6). Care is taken to avoid points of vessel flexion to avoid kinking the stent, which can potentially lead to stent-graft thrombosis. Some studies have shown that the primary site of arterial flexion occurs at the superior margin of the patella [62]. When multiple stents are needed, stent overlap in this region needs to be long enough to ensure that kinking does not occur and that components do not separate. (See 'Suitability for endovascular repair' above.)

Once the proper position is confirmed, the graft is deployed from its sheath and an appropriately sized balloon is inflated within the proximal and distal graft to ensure an adequate seal. Repeat arteriography is performed to confirm graft position and absence of any endoleaks. Due to the size of the graft delivery sheath, a percutaneous closure device is often used.

Stent-graft complications — Complications of popliteal artery stent-grafting are similar to those of any peripheral artery stent. These include bleeding, hematoma, pseudoaneurysm, stent-graft kinking, migration or fracture, or stent thrombosis (early or late). Endoleak is a complication that is unique to endograft repair of arterial aneurysm.

●Stent-graft thrombosis – In the early experience of popliteal aneurysm stent-grafting, immediate postintervention failures due to thrombosis were common. The administration of periprocedural antiplatelet agents has decreased the incidence of early thrombosis (see 'Antiplatelet therapy' below). Aggressive graft over-sizing can also cause thrombosis due to incomplete graft unfolding [57]. Other factors that increase the risk for thrombosis include stent kinking, stent fracture, the use of multiple stents, and poor outflow [5,63]. One review of 102 procedures reported a higher amputation rate in the endovascular repair population at one-year follow-up compared with the open surgery group; however, amputation-free survival did not differ at the end of follow-up [64].

●Endoleak – Endoleaks are classified in a similar manner to those complicating the endovascular repair of abdominal aortic aneurysm (figure 7). (See "Complications of endovascular abdominal aortic repair", section on 'Endoleak' and "Endoleak following endovascular aortic repair", section on 'Etiology and classification'.)

Endoleak occurs in 10 to 20 percent of patients following popliteal artery aneurysm repair [3,10,15,20,65]. Endoleak most commonly develops at the stent-graft fixation points (type I). If a type I endoleak is identified at the time of completion arteriography, additional balloon angioplasty or stent-graft placement is performed to remedy the leak. With time, arterial wall aneurysmal degeneration may change the configuration of the popliteal aneurysm, potentially leading to stent-graft migration and a delayed type I leak [33]. Ongoing surveillance is necessary to detect these leaks. Additional stenting or conversion to an open surgical bypass may be required. (See 'Graft surveillance' below.)

Type II endoleaks are due to retrograde flow from branch vessels off the aneurysm sac. Type II endoleak can be managed with ultrasound-guided thrombin injection into the aneurysm sac. Ongoing type II leak that does not resolve with thrombin injection can be approached using percutaneous coil embolization (similar with endoleak associated with endovascular abdominal aortic aneurysm repair) or a surgical approach that involves opening of the sac and oversewing the leaking branches, as described above for expanding sacs following open bypass and exclusion [10]. (See "Complications of endovascular abdominal aortic repair", section on 'Endoleak' and 'Surgical complications' above and "Endoleak following endovascular aortic repair", section on 'Etiology and classification'.)

●Stent fracture – Stent fractures can occur at points of severe flexion and may also be seen in overlapping stents. One study found stent fracture incidences in 16 percent of the patients studied [63]. However, overall stent-graft patency in those with stent fracture was not significantly different compared with those without stent graft fracture.

PERIOPERATIVE MANAGEMENT — The postprocedural course depends upon the initial clinical presentation and type of repair.

Following elective endovascular repair, the patient is admitted for observation and maintained at bedrest for four to six hours following the procedure to ensure adequate hemostasis at the groin puncture site. The patient is allowed to ambulate thereafter. Although there are no studies directly evaluating the optimal period of bedrest following endovascular popliteal aneurysm repair, randomized trials following percutaneous intervention (mostly cardiac) have used protocols that immobilize the patient for three to eight hours following removal of the groin sheath [66-71]. One randomized trial found no difference in access site complications for three hours compared with longer periods of immobilization [67]. However, we prefer to immobilize the patient for four hours post-procedure if a vascular closure device has not been used [72]. A shorter period of immobilization may be allowed if a closure device is used [73,74]. (See "Complications of diagnostic cardiac catheterization", section on 'Closure devices' and "Percutaneous arterial access techniques for diagnostic or interventional procedures", section on 'Vascular closure devices'.)

Following open surgical repair of popliteal artery aneurysm, the patient is transferred to a monitored care setting. The patency of the vascular repair is monitored with frequent pulse checks. The patient is placed at bedrest overnight and is generally allowed to ambulate the next day.

Extremity compartment syndrome — Patients with acute limb-threatening ischemia from popliteal artery aneurysm thrombosis who have not already undergone fasciotomy are monitored for compartment syndrome. (See "Acute compartment syndrome of the extremities".)

Those who have fasciotomy wounds are managed accordingly. (See "Patient management following extremity fasciotomy".)

Antiplatelet therapy — For patients in whom popliteal artery aneurysm stenting is scheduled or anticipated, we recommend periprocedural antiplatelet therapy. In retrospective reviews, antiplatelet therapy is associated with a lower incidence of early stent-graft thrombosis following endovascular repair of popliteal artery aneurysm [60,75-77]. Patients with lower extremity bypass may also benefit from antithrombotic therapy. (See "Prevention of cardiovascular disease events in those with established disease (secondary prevention) or at very high risk" and "Overview of lower extremity peripheral artery disease", section on 'Adjuncts to improve patency of revascularization'.)

Antiplatelet therapy (aspirin or clopidogrel) is recommended for all patients with peripheral artery disease, including those with large artery aneurysms, and should be initiated for those not already on chronic therapy, and continued indefinitely [2,13,78]. We give aspirin 325 to 650 mg daily starting at least 48 hours before the procedure or, if within 48 hours of the procedure, a loading dose of aspirin 650 mg given at least four hours before the procedure.

Following the procedure, we suggest dual antiplatelet therapy (aspirin plus clopidogrel) for at least four weeks if the risk for bleeding is low. Clopidogrel is commonly used following endovascular stenting at other sites and has been adopted by some following endovascular repair of popliteal artery aneurysm [60,75-77]. Postoperative clopidogrel may improve outcomes of popliteal aneurysm stent-graft repair, but randomized trials are needed to verify these observational data [75,76]. (See 'Stent-graft patency' below.)

Graft surveillance — Following popliteal aneurysm repair, patients are followed with physical examination and noninvasive vascular lab studies. A duplex scan of the bypass graft or stent-graft (image 1) is performed initially postoperatively to establish a baseline, and then at three to six months to identify areas of vein graft or stent-graft stenosis, aneurysm sac enlargement, or endoleak. Thereafter, the study is obtained annually, or more frequently initially if an open surgical bypass was used for popliteal artery aneurysm repair [23,79]. (See "Lower extremity surgical bypass techniques", section on 'Graft surveillance'.)

OUTCOMES — The major endpoints of popliteal aneurysm repair (eg, patency, limb salvage, mortality) are affected by the nature of the presenting symptoms and signs, type of repair, quality of distal runoff, and risk factors for disease progression (eg, smoking) [1,5,8,9].

Definition of terms — In discussing outcomes of open and endovascular popliteal aneurysm repair, several terms need to be understood. These include primary patency, assisted-primary patency, and secondary patency [80], each of which is defined for a specified period of follow-up (eg, three-year primary patency).

●Primary patency means that the revascularized region (bypass or stent) is open and has not required any form of reintervention.

●Assisted-primary patency means that the revascularized region (bypass or stent) is open but has required reintervention (surgery or stent) to prevent impending occlusion or progression of stenosis.

●Secondary patency means that the revascularized region (bypass or stent) has occluded at some point in the past but patency of the revascularized region was restored with some form of intervention.

Surgical repair

Bypass patency — Retrospective reviews of popliteal aneurysm bypass report overall five-year primary patency rates between 76 and 95 percent and secondary patency rates between 78 and 87 percent [5,8,40,56,81-83]. Cumulative primary and secondary patency rates at 10 years are 59 and 66 percent [56]. (See 'Definition of terms' above.)

Patency rates are higher with great saphenous vein grafts compared with polytetrafluoroethylene (PTFE) grafts. In one large retrospective review, primary and secondary patency rates for vein grafts were significantly better compared with PTFE grafts (85 and 94 percent versus 50 and 63 percent, respectively) [8].

In other reviews, the presence of adequate runoff (three vessels patent to the ankle) and a more proximal site of the distal anastomosis correlate with better long-term patency [5,84,85]. One retrospective review found that primary bypass failure was associated with smoking and poor distal runoff [5]. However, another study found no significant correlation with runoff status and primary graft patency at five years [6]. In this study, cumulative five-year patency was 95 percent; none of the patients were treated with prosthetic grafts. Ten patients with single vessel runoff did not experience graft-related problems.

The greatest influence on outcome and patency following open bypass for popliteal aneurysm repair appears to be the clinical circumstance under which the repair is performed. Elective popliteal artery bypass is associated with significantly improved outcomes (ie, graft patency, limb salvage) compared with bypass performed for acute ischemic symptoms [1,83,84]. In a retrospective review of 289 patients followed over a mean of four years, perioperative (30 day) graft thrombosis rates were 1, 4, and 9 percent for asymptomatic patients, patients with chronic symptoms, and those with acute ischemia, respectively [8].

A systematic review of 32 observational studies of acutely thrombosed popliteal aneurysms identified a significant difference in one-year primary graft patency rates in patients who had some form of thrombolysis (preoperative or intraoperative) compared with those who did not (79 versus 71 percent) [34]. However, a significant difference in limb salvage rates was not seen.

Limb loss following surgical bypass — Limb loss following elective popliteal artery bypass grafting is rare (<1 percent). Overall long-term limb salvage rates (elective and emergent) are between 96 and 98 percent [5,47]. One-year and three-year amputation rates range from 0 to 11 percent and 0 to 22 percent, respectively [3]. In a review of 1471 popliteal artery aneurysm repairs from the Vascunet registry, the amputation rate was 2 percent after elective repair and 6.5 percent after emergent repair [16].

In a large retrospective review, a Cox regression model determined that advancing age, emergency procedure, and prosthetic graft were independently associated with an increased incidence of amputation in the long-term [40]. When the indication for repair is acute aneurysm thrombosis, amputation rates range from 5 to 15 percent [5,8,34,84]. Limb loss is most likely to occur within the first month following bypass [84]. In a retrospective review of 289 patients followed over a mean of 4.3 years, outcomes for differing clinical presentations were evaluated. These included patients with no symptoms (40 percent), chronic symptoms (39 percent), or acute ischemia (21 percent) [8]. All early amputations occurred in patients with acute ischemia, and there was no limb loss in patients with chronic symptoms when great saphenous vein was used as a conduit [8]. The overall five-year limb salvage rate was 85 percent in patients with acute ischemia [8].

In a retrospective review of 234 open surgical repairs of popliteal artery aneurysm for elective and emergency indications at a single institution, the rate of amputation at 30 days was 3.8 percent (9 of 234 limbs), mostly due to thrombosis of the repair [19]. Perioperative thrombosis occurred after 18 procedures (7.7 percent). A successful thrombectomy was performed in 10 of 11 patients taken to the operating room. The remaining seven patients underwent major amputation without any attempt at thrombectomy. An adjunctive major amputation was necessary in a patient with a patent bypass for irreversible foot ischemia.

Over a mean follow-up period of 62 months (range 1 to 312 months), there were 45 thromboses and 10 additional amputations. The estimated 13 year survival rate was 50.8 percent, and the same interval, primary patency, secondary patency, and limb salvage were 55.1, 68, and 86 percent, respectively.

Mortality following bypass — Elective popliteal aneurysm repair is associated with low (<1 percent) mortality [8,19,56]. Mortality rates for patients undergoing emergent repair range from 3 to 5 percent [5,34] and are higher after rupture (11 percent in one review [16]). Late survival is similar to that of patients with atherosclerotic peripheral artery disease with studies finding 5 year and 10 year survival rates of 70 to 85 percent and 44 percent, respectively [5,47,56].

Endovascular repair — The primary factors affecting the outcome of stent-graft repair of popliteal artery aneurysms are suitable aneurysm anatomy, outflow vessels, and postoperative antiplatelet therapy.

Stent-graft patency — Immediate technical success is achieved in 96 to 100 percent of patients [20,60,76,86-91]. Following endovascular repair of popliteal artery aneurysm, small series show primary patency rates ranging between 80 to 94 percent at one year [15,21,60,75,90-95]. Secondary patency ranges from 75 and 100 percent at one year and 82 to 88 percent at three years [10,15,21,60,75,87,89-95]. In a small series of 65 patients undergoing endovascular repair for which one third of cases were emergent, the three-year primary patency was 57 percent, the secondary patency was 73 percent, and the limb salvage rate was 83 percent [96]. Durability of endovascular repair was reduced for patients with diabetes, those who were intervened upon acutely, and those with poor tibial runoff.

Limb loss — The incidence of limb loss following elective popliteal artery endovascular aneurysm repair is low (<1 percent) [10,95]. Overall amputation rates are 0 to 3 percent at one-year follow-up and 3 to 4 percent at three-year follow-up [3].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic and other peripheral aneurysms".)

SUMMARY AND RECOMMENDATIONS

●Popliteal artery aneurysm presents in a variety of ways. Many patients are asymptomatic, while others have symptoms referable to the aneurysm, such as pain with ambulation (claudication) or acute limb ischemia due to aneurysm thrombosis or distal embolization. (See 'Introduction' above and "Popliteal artery aneurysm".)

●Repair of popliteal artery aneurysm is indicated for patients with symptomatic popliteal artery aneurysms (eg, acute limb ischemia, disabling claudication), and in selected asymptomatic patients depending upon the size of the aneurysm and presence of thrombus. (See 'Indications' above and "Popliteal artery aneurysm", section on 'When to and not to intervene'.)

●The goal of popliteal artery aneurysm repair is to eliminate the aneurysm from the circulation and maintain perfusion to the extremity. Open surgical bypass and endovascular stent-grafting each accomplish these goals with differing advantages, disadvantages, and types of complications. (See 'Surgical bypass' above and 'Endovascular aneurysm repair' above.)

●Prior to repair of popliteal artery aneurysms, the patient's clinical condition, vascular anatomy (including the presence of other aneurysms), and medical comorbidities are evaluated to define the patient's risk for repair and to aid in choosing the approach to repair. (See 'Preoperative evaluation' above.)

●We advocate an individualized approach to popliteal aneurysm repair taking into account the degree of any acute limb ischemia, the patient's medical comorbidities, and their vascular anatomy (suitability for endograft, status of the proximal/distal circulation, coexistent aneurysm, availability of vein conduit). (See 'Open versus endovascular repair' above and 'Outcomes' above.)

•Under elective circumstances:

For patients with a high perioperative surgical risk and suitable anatomy for endografting, we suggest endovascular repair rather than open repair (Grade 2C). (See 'Suitability for endovascular repair' above.)

For patients with low perioperative surgical risk and who have adequate vein conduit, we suggest open surgical repair rather than endovascular repair (Grade 2C). Endovascular repair is associated with an increased risk of early (30 day) reintervention and early (30 day) graft thrombosis, but longer-term secondary patency rates appear to be similar to open repair. In those without adequate vein conduit, endografting is an acceptable alternative provided the patient's vascular anatomy is suitable for endograft placement.

For patients in whom an open surgical approach is chosen and the popliteal artery aneurysm is focal and confined to the popliteal fossa, we suggest a posterior approach rather than a medial approach (Grade 2C). For practitioners who are not familiar with the technique, a medial approach is an acceptable alternative. More extensive aneurysms that involve the superficial femoral artery or distal popliteal artery necessitate a medial approach.

•Under emergent circumstances (ie, acute thrombosis, rupture):

Thrombolytic therapy is appropriate for most patients with acute limb ischemia of less than 14 days duration who have a low risk for developing myonecrosis and ischemic nerve damage during the period required to achieve revascularization. This issue is discussed in more detail elsewhere. (See "Clinical features and diagnosis of acute lower extremity ischemia", section on 'Summary and recommendations'.)

For patients with distal runoff (two or three vessel runoff) that is adequate following thrombolytic therapy, the decision for open repair versus endovascular repair is based upon the level of perioperative surgical risk and anatomic suitability, as with elective repair.

For patients with distal runoff that is not adequate to support endovascular repair following thrombolysis but a target distal to the popliteal artery is identified, we suggest revascularization to that target (Grade 2C). For these patients, we further suggest using a medial approach, which facilitates thromboembolectomy or intraoperative thrombolytic therapy, rather than a posterior approach (Grade 2C).

●For patients in whom popliteal artery aneurysm stenting is scheduled or anticipated, we recommend periprocedural antiplatelet therapy (aspirin or clopidogrel) (Grade 1B). For those patients not on chronic aspirin therapy, we give aspirin 325 to 650 mg daily starting at least 48 hours before the procedure or, if within 48 hours of the procedure, a loading dose of aspirin 650 mg given at least four hours before the procedure. Following popliteal artery aneurysm stenting for patients in whom the risk of bleeding is low, we suggest dual antiplatelet therapy (aspirin plus clopidogrel) for at least four weeks (Grade 2C). (See 'Antiplatelet therapy' above.)

●Following open or endovascular repair of popliteal artery aneurysm, duplex ultrasound surveillance should be performed postoperatively to establish a baseline, and then at six months postoperatively to identify areas of stenosis in the graft or stent-graft, aneurysm sac enlargement, and for endovascular repair, endoleak, or stent-graft fracture. Thereafter, duplex surveillance is obtained annually unless symptoms develop. (See 'Graft surveillance' above.)

●The outcomes of popliteal artery aneurysm repair (eg, graft patency, limb salvage, mortality) are affected by the nature of the presenting symptoms and signs, type of repair, quality of distal runoff, and risk factors for aneurysmal disease progression (eg, smoking). (See 'Outcomes' above.)