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The Lisbon Agreement on Femoroacetabular Impingement Imaging—part 1: overview

A Correction to this article was published on 17 July 2020

This article has been updated



Imaging assessment for the clinical management of femoroacetabular impingement (FAI) syndrome remains controversial because of a paucity of evidence-based guidance and notable variability in clinical practice, ultimately requiring expert consensus. The purpose of this agreement is to establish expert-based statements on FAI imaging, using formal techniques of consensus building.


A validated Delphi method and peer-reviewed literature were used to formally derive consensus among 30 panel members (21 musculoskeletal radiologists and 9 orthopaedic surgeons) from 13 countries. Forty-four questions were agreed on, and recent relevant seminal literature was circulated and classified in five major topics (‘General issues’, ‘Parameters and reporting’, ‘Radiographic assessment’, ‘MRI’ and ‘Ultrasound’) in order to produce answering statements. The level of evidence was noted for all statements, and panel members were asked to score their level of agreement with each statement (0 to 10) during iterative rounds. Either ‘consensus’, ‘agreement’ or ‘no agreement’ was achieved.


Forty-seven statements were generated, and group consensus was reached for 45 (95.7%). Seventeen of these statements were selected as most important for dissemination in advance. There was no agreement for the two statements pertaining to ‘Ultrasound’.


Radiographic evaluation is the cornerstone of hip evaluation. An anteroposterior pelvis radiograph and a Dunn 45° view are recommended for the initial assessment of FAI although MRI with a dedicated protocol is the gold standard imaging technique in this setting. The resulting consensus can serve as a tool to reduce variability in clinical practices and guide further research for the clinical management of FAI.

Key Points

FAI imaging literature is extensive although often of low level of evidence.

Radiographic evaluation with a reproducible technique is the cornerstone of hip imaging assessment.

MRI with a dedicated protocol is the gold standard imaging technique for FAI assessment.

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Change history

  • 17 July 2020

    The original version of this article, published on 14 May 2020, unfortunately contained a mistake.







Alpha angle


Acetabular index




Cross-over sign


Computed tomography


CT arthrography


Direct MR arthrography


European Society of Musculoskeletal Radiology


Femoroacetabular impingement


Femoroacetabular impingement syndrome


Femoral head-neck


Femoral offset




Hip preservation surgery


Ischial spine sign


Magnetic resonance arthrography


Magnetic resonance imaging




Posterior wall sign


Reference intervals


Centre-edge angle of Wiberg


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Correspondence to Vasco V. Mascarenhas.

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The original version of this article was revised: The spelling of Radhesh Lalam’s name was incorrect.

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Mascarenhas, V.V., Castro, M.O., Rego, P.A. et al. The Lisbon Agreement on Femoroacetabular Impingement Imaging—part 1: overview. Eur Radiol 30, 5281–5297 (2020).

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  • Hip
  • Femoroacetabular impingement
  • Diagnostic imaging
  • Orthopaedics
  • Guideline