***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objectives : The objective is to report the feasibility and technique of treating popliteal artery aneurysms ( PAA ) with a stent made of nitinol rings externally supported by thin polyester ( Anaconda limbs ) . Background : PAA are the most common peripheral aneurysms . The main limitations of stents used in these setting s are : short lengths , longitudinal and horizontal compliance mismatch ; graft failure from angulation and movement at the joint level ; and dislodgment . Methods : This is a prospect i ve multicenter cohort study of consecutive symptomatic and asymptomatic PAA treated in tertiary vascular centers . Outcomes included patency of the stent and postoperative time‐to‐independent‐ambulation and to‐climb‐a‐flight‐of‐stairs . Results : Fourteen PAA were treated in 12 men , age 72 ± 3 years . The median ASA classification was 2.5 . The length of artery covered was 147 ± 41 mm . The PAA diameter was 31 ± 5 mm , 6 were symptomatic . One stent was used in 6 aneurysms , two in 7 , and three in 1 . The average stent diameter was 10 ± 1 mm . The length of the proximal neck was 24 ± 6 mm with a diameter of 9.8 ± 1.9 , and length of the distal neck 23 ± 3 mm with a diameter of 8.7 ± 1.2 mm . In 6 aneurysms , the stent crossed the knee joint . There was no mortality , and one stent occluded ( primary patency 93 % at 6 ± 3 months ) . The median hospital stay was 1.7 days , time to independent ambulation was 3 hr and the time to climbing a flight of stairs was 1 day . Conclusions : The use of Anaconda limbs for endovascular repair of PAA is feasible and safe . © 2008 Wiley‐Liss , AIM The aim of this prospect i ve comparative study was to compare the results of 8-years experience of endovascular treatment ( ET ) of popliteal aneurysms ( PAs ) using the Hemobahn/Viabahn endograft with those achieved with open repair ( OR ) . Endpoints were primary and secondary patency rate . METHODS The study was a prospect i ve r and omized clinical trial from January 1999 to December 2003 and a prospect i ve comparative study from January 2004 to December 2006 . Patients with an asymptomatic aneurismal lesion in the popliteal artery 2 cm at angio-computed tomography were included in the study . Indication for ET was PA ( proximal and distal neck length > 1 cm ) ; contraindications were : 1 ) age < 50 years ; 2 ) poor distal run-off ; 3 ) contraindication to antiplatelet , anticoagulant or thrombolytic therapy .  RESULTS Between January 1999 and December 2006 , of a total of 42 patients with 48 PA , 27 were treated with OR ( group A ) and 21 with ET ( group B ) . The primary patency rate was 100 % in group A and 80.9 % in group B at 12 months and 71.4 % and 88.1 % , respectively , at 72 months ; the secondary patency rate at 72 months was 88.15 % and 85.9 % in groups A and B , respectively . No statistical differences were observed at the log-rank test . During the entire study period , 3 ( 14.3 % ) patients in group B required conversion to open surgery because of endograft occlusion . CONCLUSION Within the power limitations of this study , ET for asymptomatic PA in patients with suitable anatomy can be considered safe , with long-term results comparable with those of OR OBJECTIVE The purpose of this study was to compare outcomes after endovascular repair ( ER ) and contemporary open repair ( OR ) of  popliteal artery aneurysms ( PAAs ) . METHODS Clinical data of PAA patients treated between 2005 and 2012 were review ed . Primary end points were major adverse events ( MAEs ) including mortality , major amputation , patency , complications , and re interventions . RESULTS A total of 149 PAAs were treated in 120 patients ( mean age , 74 ± 10 years ) .  ER was performed in 42 limbs of 35 men ( mean age , 81 ± 6.5 years ) , in 32 electively and in 10 emergently . Technical success was 98 % . The 30-day MAEs were more frequent after emergent repair ( 50 % vs 9 % ; odds ratio [ OR ] , 9.67 ; 95 % confidence interval [ CI ] , 1.74 - 54 ; P = .01 ) ; mortality and amputation rate was 0 % after elective repair , 20 % after emergent repair . Mean follow-up was 2.6 years ( 1 month-6.5 years ) ; 3-year freedom from MAEs was lower after emergent repair than after elective repair ( 40 % vs 66 % ; hazard ratio [ HR ] , 3.13 ; 95 % CI , 1.10 - 8.85 ; P = .03 ) . OR was performed in 107 limbs of 91 patients ( 90 men ; mean age , 71 ± 9.6 years ) , in 93 electively and in 14 emergently . The 30-day MAEs were more frequent after emergent repair ( 43 % vs 5 % ; OR , 13 ; 95 % CI , 3.29 - 53 ; P < .001 ) ; mortality was 1 % after elective repair , 0 % after emergent cases . Amputation rate was 0 % for both elective and emergent repairs . Mean follow-up was 3.8 years ( 1 month-8.4 years ) ; 3-year freedom from MAEs was lower after emergent repair ( 50 % vs 80 % ; HR , 3.78 ; 95 % CI , 1.55 - 9.20 ; P = .003 ) . The 30-day MAE rates were equivalent between ER and OR independent of urgency of repair ( elective : OR , 1.82 ; 95 % CI , 0.41 - 8.09 ; P = .43 ; emergent : OR , 1.33 ; 95 % CI , 0.26 - 6.81 ; P = .73 ) . In elective interventions , ER had a trend to decreased freedom from MAEs ( 66 % vs 80 % at 3 years ; HR , 1.93 ; 95 % CI , 0.92 - 4.07 ; P = .08 ) ; freedom from reintervention was lower after ER ( 72 % vs 88 % ; HR , 2.41 ; 95 % CI , 1.02 - 5.70 ; P = .046 ) . In emergent interventions , 1-year freedom from MAEs was similar ( 40 % vs 50 % ; HR , 1.36 ; 95 % CI , 0.49 - 3.74 ; P = .55 ) . Emergent ER and poor runoff predicted MAEs . CONCLUSIONS Our study failed to prove the superiority of ER over OR . If anatomy is suitable , ER of PAA in the elderly and high-risk patients is justified . For emergent PAA repairs , MAEs are frequent after both ER and OR ; ER has not changed the severe prognosis of acute limb ischemia from PAA . A multicenter r and omized controlled trial of PAA patients with acute presentation is warranted BACKGROUND Aim of this study was to retrospectively compare perioperative ( < 30 days ) and 2-year results of open and endovascular management of popliteal artery aneurysms ( PAAs ) in a single-center experience . METHODS From January 2005 to December 2010 , 64 PAAs in 59 consecutive patients were operated on at our institution ; in 43 cases , open repair was performed ( group 1 ) , whereas the remaining 21 cases had an endovascular procedure ( group 2 ) . Data from all the interventions were prospect ively collected in a dedicated data base , which included main preoperative , intraoperative , and postoperative parameters . Early results in terms of mortality , graft thrombosis , and amputation rates were analyzed and compared by χ(2 ) text or Fisher exact text . The surveillance program consisted of clinical and ultrasonographic examinations at 1 , 6 , and 12 months and yearly thereafter . Follow-up results ( survival , primary and secondary patency , limb salvage ) were analyzed by Kaplan-Meier curves , and differences in the two groups were assessed by log-rank test . RESULTS There were no differences between the two groups in terms of sex , age , risk factors for atherosclerosis , and comorbidities ; PAAs were symptomatic in 48 % of cases in group 1 and in 29 % in group 2 ( P = 0.1 ) . Fifteen patients with mild-to-moderate acute ischemia due to PAA thrombosis underwent preoperative intra-arterial thrombolysis , 13 in group 1 and 2 in group 2 . In open surgery group , nine cases were treated with aneurysmectomy and prosthetic graft interposition , and in seven cases , the aneurysm was opened and a prosthetic graft was placed inside the aneurysm . In 27 cases , ligation of the aneurysm with bypass grafting ( 21 prosthetic grafts and 6 autologous veins ) was carried out . In group 2 , 20 patients had endoprosthesis placement , whereas in the remaining patient , a multilayer nitinol stent was used . There was one perioperative death in a patient of group 2 who underwent concomitant endovascular aneurysm repair and PAA endografting . Cumulative 30-day death and amputation rate was 4.5 % in group 1 and 4.7 % in group 2 ( P = 0.9 ) . Follow-up was available in 61 interventions ( 96 % ) with a mean follow-up period of 22.5 months ( range : 1 - 60 ) . Estimated primary patency rates at 24 months were 78.1 % in group 1 and 59.4 % in group 2 ( P = 0.1 ) . Freedom from reintervention rates at 24 months were 79 % in group 1 and 61.5 % in group 2 ( P = 0.2 ) ; estimated 24-month secondary patency rates were 81.6 % in group 1 and 78.4 % in group 2 ( P = 0.9 ) , and freedom from amputation rates were 92.7 % and 95 % , respectively ( P = 0.7 ) . CONCLUSIONS Endovascular treatment of PAAs provided , in our initial experience , satisfactory perioperative and 1-year results , not significantly different from those obtained with prosthetic open repair in patients with similar clinical and anatomical status . There is , however , a trend toward poorer primary patency rates among patients endovascularly treated , who also seem to require more frequently a reintervention BACKGROUND We describe the organization of a prospect i ve , r and omized , multicenter trial comparing the effectiveness of  open popliteal artery aneurysm repair ( OPAR ) and endovascular popliteal artery aneurysm repair ( EPAR ) of asymptomatic popliteal artery aneurysms ( PAAs ) as an example for how to use the Vascular Quality Initiative ( VQI ) framework . Given that many centers participate in the VQI , this model can be used to perform multicenters ' prospect i ve trials on very modest budget . METHODS VQI prospect ively collects data on many vascular procedures . These data include many important perioperative , intraoperative , and postoperative details regarding both patients and their procedures . We describe a study where minimal changes to the collected data by participating centers can provide level-1 evidence regarding a significant clinical question . Data will be collected using modified VQI forms within the existing VQI data reporting structure . We plan to enroll 148 patients with asymptomatic PAAs into the open and endovascular surgery cohorts . Patients from participating VQI centers will be r and omized 1:1 to either OPAR or EPAR and will be followed for an average of 2.5 years . Our primary hypothesis is that major adverse limb event-free survival is lower in the EPAR cohort and that EPAR is associated with more secondary interventions , improved quality of life , and decreased length of stay . The budget for this trial is fixed at $ 10,000/year for the course of the study , and the trial is judged to be feasible because of the functionality of the VQI platform . CONCLUSIONS Using the existing VQI infrastructure , Open versus Endovascular Repair of Popliteal Artery Aneurysm will provide level 1 data for PAA treatment on a modest budget . The proposed trial has an adequately powered comparative design that will use objective performance goals to describe limb-related morbidity and procedural reintervention rates 
    Output:
    
Endovascular repair is associated with inferior perioperative and postoperative outcomes compared with open repair