Purpose
The aim of this study was to determine the prevalence of radiographic findings suggestive
of femoroacetabular impingement (FAI) in asymptomatic individuals.
Methods
A systematic review was performed using Preferred Reporting Items for Systematic Reviews
and Meta-Analyses (PRISMA) guidelines. Studies reporting radiographic, computed tomographic,
or magnetic resonance imaging (MRI) findings that were suggestive of FAI in asymptomatic
volunteers were included. Cam, pincer, and combined pathologic conditions were investigated.
Results
We identified 26 studies for inclusion, comprising 2,114 asymptomatic hips (57.2%
men; 42.8% women). The mean participant age was 25.3 ± 1.5 years. The mean alpha angle
in asymptomatic hips was 54.1° ± 5.1°. The prevalence of an asymptomatic cam deformity
was 37% (range, 7% to 100% between studies)—54.8% in athletes versus 23.1% in the
general population. Of the 17 studies that measured alpha angles, 9 used MRI and 9
used radiography (1 study used both). The mean lateral and anterior center edge angles
(CEAs) were 31.2° and 30°, respectively. The prevalence of asymptomatic hips with
pincer deformity was 67% (range 61% to 76% between studies). Pincer deformity was
poorly defined (4 studies [15%]; focal anterior overcoverage, acetabular retroversion,
abnormal CEA or acetabular index, coxa profunda, acetabular protrusio, ischial spine
sign, crossover sign, and posterior wall sign). Only 7 studies reported on labral
injury, which was found on MRI without intra-articular contrast in 68.1% of hips.
Conclusions
FAI morphologic features and labral injuries are common in asymptomatic patients.
Clinical decision making should carefully analyze the association of patient history
and physical examination with radiographic imaging.
Level of Evidence
Level IV, systematic review if Level II-IV studies.
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Article info
Publication history
Published online: January 28, 2015
Accepted:
November 26,
2014
Received:
July 2,
2014
Footnotes
See commentary on page 1205
The authors report the following potential conflict of interest or source of funding: S.N. receives support from Össur, Stryker, AlloSource, Arthrex, Athletico, DJ Orthopaedics, Linvatec, Miomed, and Smith & Nephew and M.S. receives support from Smith & Nephew and Linvatec.
Identification
Copyright
© 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
