Popliteal artery aneurysms (PAA) are local enlargements of the popliteal artery to more than 12 mm and at least 1.5 times the diameter of the proximal arterial segment [1]. In PAA with a diameter of 20–30 mm, the mean annual growth rate is 3 mm, while for a diameter of more than 30 mm it is 3.7 mm [2].
Although the popliteal artery is the most common location of peripheral arterial aneurysms, PAA nonetheless occurs comparatively rarely. Its prevalence in men over 65 years of age is 1% [3]. PAA in women is extremely rare; almost all patients reported in the literature are male [4]. PAA prevalence is significantly increased in patients with aortic aneurysms [5]. A publication from 2016 reports a PAA prevalence of 19% in patients with abdominal aortic aneurysm (AAA) [6]. In patients with bilateral PAA, the prevalence of AAA is 69% [3].
About 80% of PAA remain asymptomatic until the time of diagnosis [7], but approximately 14% of clinically silent PAA become symptomatic each year [8]. The symptoms correspond to the picture of peripheral arterial occlusive disease with stenoses and occlusions, intermittent claudication, microemboli, pain at rest, and trophic disorders. PAA may also be the cause of acute leg ischaemia, which leads to major amputation in up to 40% of cases [9].
The outcomes after treatment of symptomatic PAA are usually considerably worse than after elective management. The American Heart Association therefore recommends early elective treatment of asymptomatic PAA from a diameter of 2 cm onwards, in order to reduce the risk of thromboembolic complications and limb loss [10].
In 1912, Erich Lexer performed the first PAA exclusion with vein interposition via a posterior approach; in 1969, W.S. Edwards carried out proximal and distal ligation of the PAA together with an autologous greater saphenous vein bypass, which is still regarded as the therapeutic standard today [11, 12].
Endovascular treatment of PAA was first proposed in 1994; however, owing to the rarity of the disease and the lack of large randomised trials, there are still no evidence level A recommendations for the choice of therapeutic procedure.
The Swedish Vascular Registry (Swedvasc) retrospectively analysed 717 PAA repairs with a mean follow-up of 7.2 years. After one year, the primary patency rates were: posterior approach—vein 85%, vascular prosthesis 81%; medial approach—vein 90%, vascular prosthesis 72%. The amputation rate within one year was 8.8%. A further 17 amputations occurred over the long term, so that a total of 11% amputations were registered. The long-term risk of amputation was twice as high with the use of vascular prostheses as with the use of autologous vein material, and about two and a half times as high in emergency procedures for acute ischaemia as in elective procedures. The risk of aneurysm expansion after PAA repair via a medial approach was significantly higher than after repair via a posterior approach (33% vs. 8.3%) [13]. Further studies also concluded that the posterior approach is superior in terms of primary and secondary patency rates as well as reintervention-free survival, and that autologous vein material is to be preferred whenever possible [14–20].