Popliteal entrapment syndrome Sidhartha Sinha, MA, MRCS,a Jon Houghton, MRCP, MFSEM,b Peter J. Holt, PhD, FRCS,a Matt M. Thompson, MD, FRCS,a Ian M. Loftus, MD, FRCS,a and Robert J. Hinchliffe, MD, FRCS,a London and Surrey, United Kingdom Introduction: Popliteal entrapment syndrome (PES) is a rare but important cause of intermittent claudication in young people. Controversy exists about optimal strategies for diagnosis and management, particularly for variants such as functional popliteal entrapment. The aim of this review was to systematically catalog the published English-language literature on PES and to determine if evidence-based guidelines for management could be formulated. Methods: An electronic search using the MEDLINE, EMBASE, Cochrane Library, AMED, and CINAHL databases was performed to identify articles about PES published from 1947 to December 2010. The systematic review conformed to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement standards. Prospective studies and retrospective case series with more than five patients with arterial, venous, nerve, and combined neurovascular entrapment were analyzed on a study-by-study narrative basis. Results: The search identified 291 articles, and 44 were included. Of these, 30 studies were on popliteal artery entrapment syndrome (PAES). No relationship was found between duration of symptoms and the presence of irreversible arterial injury. Each study used a median of three diagnostic tests (range, 1-6). Arteriography was used in 28 of 30 studies to diagnose PAES, with an estimated mean sensitivity of 97% (range, 85%-100%). Twenty-three studies described arterial reconstructive procedures, with a median failure rate of 27.5% (range, 0%-83%). The proportion of patients asymptomatic after surgery was reported in only 12 of 30 studies, with a median value of 77% (range, 70%-100%). Conclusions: A large volume of predominantly retrospective clinical data exists on PES. A subset of studies describe a significant failure rate after surgery, but study quality is insufficient to derive robust conclusions allowing recommenda- tion of any one particular diagnostic modality or operative procedure over another. Improvements in management of this condition are unlikely to result from publication of further retrospective case series, and clinicians should concentrate on prospectively collected data with predefined inclusion criteria, outcome measures, follow-up protocols, and transparent standardized reporting criteria. (J Vasc Surg 2012;55:252-62.) Intermittent claudication (IC), as a manifestation of progressive injury to the popliteal artery with subsequent atherosclerotic peripheral vascular disease (PVD) in limb loss has been described.3,4 older patients, is a frequently encountered symptom in Although the anatomic basis for entrapment of the vascular surgical practice. However, IC may also be popliteal artery was first described in 1879, the clinical described by a younger subset of patients without any condition associated with such anatomic abnormalities was risk factors for PVD and can present a diagnostic chal- not described until 1958.3 Knowledge of the syndrome— lenge.1 Popliteal entrapment syndrome (PES) describes and of variations in the underlying anatomic abnormalities—was a group of conditions in which compression of the subsequently advanced through sporadic publication of popliteal artery, popliteal vein, and tibial nerve (singly or case reports and small case series.3 The formation of the in combination) in the popliteal fossa by surrounding Popliteal Vascular Entrapment Forum in 1998 was an musculoskeletal structures occurs to a degree sufficient attempt to gain some consensus on the anatomic classifica- to cause vascular and neurogenic symptoms.2 Popliteal tion of the different types of PES (Fig 1), but it was artery entrapment syndrome (PAES) is believed to be acknowledged that the quality of available studies on which responsible for a significant proportion of IC in young to base management guidelines was poor, and attempts at patients and should not be considered benign, because evidence synthesis have previously been through narrative commentary rather than systematic review.3,5 PES can be difficult to differentiate from other causes of From the St George’s Vascular Institute, Londona; and Defence Medical Rehabilitation Centre, Headley Court, Surrey.b exertional lower leg pain in young patients, and proposed Competition of interest: none. management algorithms are complex or based on guide- Additional material for this article may be found online at www.jvascsurg.org. lines for atherosclerotic PVD, with particular inconsisten- Reprint requests: Robert J. Hinchliffe, MD, FRCS, Senior Lecturer, Con- cies in the diagnosis of functional popliteal entrapment.5,6 sultant in Vascular Surgery, St George’s Vascular Institute, 4th Flr, St James Wing, St. George’s Healthcare NHS Trust, Blackshaw Rd, London Furthermore, although open surgery was traditionally recom- SW17 0QT (e-mail: [email protected]). mended as the treatment of choice for PES, the development The editors and reviewers of this article have no relevant financial relationships of endoluminal revascularization (catheter-directed throm- to disclose per the JVS policy that requires reviewers to decline review of any bolysis) and endovascular techniques has fueled interest in manuscript for which they may have a competition of interest. complementary treatment strategies.7,8 As a consequence, 0741-5214/$36.00 Copyright © 2012 by the Society for Vascular Surgery. there remains a lack of consensus regarding the most effec- doi:10.1016/j.jvs.2011.08.050 tive strategy for diagnosis and treatment of PES. The 252 JOURNAL OF VASCULAR SURGERY Volume 55, Number 1 Sinha et al 253 Type I Popliteal artery running medial to the medial head of gastrocnemius Type II Medial head of gastrocnemiuslaterally attached Type II Accessory slip of gastrocnemius/fibrous bands arising from medial head of gastrocnemius Type IV Popliteal artery passing below popliteus muscle/fibrous bands arising from popliteus Type V Primarily venous entrapment Type VI Other variants Type F Functional entrapment Fig 1. Popliteal Vascular Entrapment Forum classification for popliteal entrapment syndrome (adapted from Di Marzo and Cavallaro,5 figures reproduced from Pillai et al2 with permission). objective of this study was to systematically categorize the relevant titles and complemented by hand searches of ref- published English-language literature on PES, collate the erence lists of the included articles. The literature review evidence, and determine if evidence-based guidelines for conformed to Preferred Reporting Items for Systematic management could be formulated. Reviews and Meta-analyses (PRISMA) statement stan- dards.9 METHODS Articles that met the inclusion criteria were further A systematic review of PES was performed by electron- classified according to the pathology described (ie, entrap- ically searching the medical literature published from 1947 ment of artery, vein, and/or nerve), and two authors (S.S., to December 2010 using EMBASE Classic, EMBASE, R.H.) independently abstracted the data. Data were col- Ovid-MEDLINE, Ovid-MEDLINE in-process and other lected on patient demographics (age, sex), disease presen- nonindexed citations, AMED, CINAHL, the Cochrane tation (symptoms, laterality), diagnostic adjuncts, type of Database of Systematic Reviews, the Cochrane Database of treatment, duration of follow-up, and outcome measures Controlled Trials, and Elsevier’s ScienceDirect catalog. and summarized in evidence tables as a study-by-study The search strategy was limited to English-language articles narrative. Outcome measures of interest were mortality and used the following terms: “popliteal” adj/adj2/adj3 rates, complication rates (eg, graft failure and amputa- “entrapment” and “popliteal” adj/adj2/adj3 “compres- tions), successful relief of symptoms in operated-on symp- sion” in titles and abstract fields for all databases. In addi- tomatic limbs, successful prevention of symptoms in operated- tion for EMBASE and MEDLINE, the exploded term on asymptomatic limbs, and results for conservatively “popliteal” was combined with the keywords “entrap- managed limbs. ment” and “compression”. Study quality was assessed by examining risk of Inclusion criteria for articles were prospective studies bias using validated Cochrane methodology.10 The qual- and retrospective case series with more than five patients. ity of the study was based on the risks of bias and was We excluded case reports, case series with fewer than five translated into a level of evidence according to the patients, letters, review articles, and commentaries. The Scottish Intercollegiate Guidelines Network (SIGN) in- electronic search results were manually reviewed to retrieve strument.11 JOURNAL OF VASCULAR SURGERY Volume 55, Number 1 Sinha et al 255 Table I. Summary characteristics/results of the studies included in the systematic review Patients Limbs Operated Asymptomatic SIGN Study (year) Pathology Study type (No.) (No.) Diagnostic tests used (%) (%) levela Di Cesare (1994)22 PAES Prospective 6 10 Doppler US/ABPI, MRI, 20 NS/UC 2– DSA Forster (1997)23 PAES Prospective 9 17 Doppler US/ABPI, MRA, 100 NS/UC 2– DSA Greenwood (1986)24 PAES Retrospective 7 12 ETT, PVR, DSA 67 NS/UC 3 Kim (2006)25 PAES Retrospective 12 23 Doppler US/ABPI, MRI, NS/UC NS/UC 3 MRA, CT, CTA, DSA Ozkan (2008)26 PAES Retrospective 6 7 MRI, DSA 83 NS/UC 3 Hai (2008)27 PAES Retrospective