Gupta et al Mar • Apr 2014
“cam” deformity. Each type of bony abnormality can be seen
in isolation or in combination and can lead to FAI.11,15,17,23 In
the past 2 decades, many advances have been made in the
recognition and management of this condition that have led
to improved patient outcomes. Despite improved outcomes,
there remains the opportunity for future advancements. The
purpose of this review is to describe the current evidence and
future directions of the anatomy and pathophysiology, imaging,
biomechanics, clinical decision making, and clinical outcomes
of FAI treatment options.
emoroacetabular impingement (FAI) is a common cause
of hip pain in young adults. FAI can be the result of an
acetabular-sided “pincer” deformity or a femoral-sided
AnAtomy And PAthoPhysiology
Femoroacetabular impingement can result from a cam
deformity,11,13 where there is loss of sphericity of the femoral
head, or from a pincer deformity,11,52 where there is focal or
global acetabular overcoverage of the femoral head. There is a
sex-related difference, with cam lesions more prevalent in
men and acetabular overcoverage more prevalent in
women.13,42,53 Recent studies, however, have demonstrated that
such findings are less likely to be seen in isolation.11,13 Rather,
a combination of these pathologies is more commonly present,
and failure to identify and treat this can lead to undesirable
What’s New in Femoroacetabular
Impingement Surgery: Will We Be
Better in 2023?
Anil K. Gupta, MD, MBA,† Geoffrey D. Abrams, MD,‡ and Shane J. Nho, MD, MS*§
Context: Femoroacetabular impingement (FAI) has been described as a common cause of hip pain in young adults. This
leads to abnormal hip joint mechanics and contact pressures. The associated pathomechanics can lead to the development
of early osteoarthritis. Better understanding of the anatomy and pathophysiology, biomechanics, and diagnostic and thera-
peutic advances has led to improved clinical outcomes. A growing body of evidence has set the foundation for future prog-
ress in the treatment of this commonly encountered condition.
Evidence Acquisition: The PubMed database was searched for English-language articles pertaining to FAI over the past
15 years (1998-2013).
Study Design: Retrospective literature review.
Level of Evidence: Level 4.
Results: The authors evaluated and discussed the current evidence regarding the anatomy, physiology, biomechanics,
imaging, and clinical outcomes of surgical intervention for FAI. Based on this information, future directions for improving
the diagnosis and management of FAI are proposed.
Conclusion: There remains a diverse approach to the diagnosis and management of cam- and/or pincer-type FAI. Recent
advances in clinical diagnosis, imaging, indications, and arthroscopic techniques have led to improved outcomes and have
set the foundation for future progress in the management of this condition.
Strength of Recommendation Taxonomy (SORT): B
Keywords: femoroacetabular impingement; surgical; biomechanics; imaging
[ Orthopaedic Surgery ]
From †Sports Medicine and Shoulder Surgery, Florida Orthopaedic Institute, Tampa, Florida, ‡Department of Orthopedic Surgery, Stanford University, and Veterans
Administration, Palo Alto, California, and §Department of Orthopedic Surgery, Division of Sports Medicine, Rush University Medical Center, Chicago, Illinois
*Address correspondence to Shane J. Nho, MD, MS, Department of Orthopedic Surgery, Division of Sports Medicine, Rush University Medical Center, 1611 West Harrison
Street, Suite 300, Chicago, IL 60612 (e-mail: firstname.lastname@example.org).
The following author declared potential conflicts of interest: Shane J. Nho, MD, MS, is a consultant for Stryker, Pivot Medical, and Ossur. He has grants pending for the
Arthroscopic Association of North America, Stryker, and Allosource. He holds stock or stock options in Pivot Medical.
© 2013 The Author(s)
vol. 6 • no. 2 SPORTS HEALTH
Up to 90% of patients with labral pathology have a
morphologic abnormality of the femoral head-neck junction
or acetabulum.13,16,19,23 Asphericity of the femoral head can lead
to early contact and shear stresses of the anterior-superior
acetabular rim as the hip is brought into flexion and internal
rotation.2,6,7 This can lead to prearthritic pain, early chondral
delamination, and associated labral pathology.8 Similarly,
acetabular overcoverage, both focal and global, can cause
abnormal impaction at the labrum during hip joint motion, as
well as a contrecoup injury to the posteroinferior acetabulum.23
Bedi et al8,9 described static and dynamic factors associated
with prearthritic hip pain. Static factors include anterior
or lateral acetabular undercoverage, femoral anteversion,
and femoral valgus. These factors lead to asymmetric
joint loading and chondral wear during static activities (ie,
stance).8,9 Dynamic factors include cam-type deformity and
acetabular overcoverage. As the hip is dynamically flexed,
there is abnormal engagement between the femoral head
and acetabulum. This alters the mechanics of the joint
and surrounding musculature, leading to pain and early
chondrolabral degeneration.8,9 Dynamic extra-articular
impingement factors, including femoral retroversion, femoral
varus, trochanteric impingement, and anterior-inferior iliac
spine (AIIS) impingement, also occur as the hip is brought into
flexion and/or abduction.8,9
Radiographic assessment of FAI, including true anteroposterior
pelvis, false-profile, cross-table lateral, frog-leg lateral, and 45°
lateral Dunn views, provides useful static evaluation for femoral
or acetabular-sided bony lesions.5,12,58 The ability to extrapolate
spherical pathology from 2-dimensional imaging, however, can
be difficult. For this reason, multiple radiographic views have
been suggested to diagnose cam and pincer deformities. In a
comparative study, Nepple et al48 evaluated the sensitivity and
specificity of specific radiographic views in predicting cam-
type FAI diagnosed by radial-oblique CT reformats (considered
gold standard). They found that a complete radiographic series,
including an anteroposterior pelvis, 45° lateral Dunn, cross-
table lateral, and frog-leg lateral, was 86% to 90% sensitive in
detecting abnormal alpha angles on CT. In an evaluation of the
alpha angle measured on a cross-table lateral view with the leg
in 15° of internal rotation or on the Dunn view, Beaule et al5
found that patients with an alpha angle greater than 65° had
significantly increased risk of cartilage damage.
Radiographic imaging to detect pincer-type deformity can be
challenging. For example, alterations in pelvic tilt and rotation
can influence interpretations of acetabular pathomorphology;
as a result, pincer deformities can be either unrecognized or
falsely identified. In a cadaveric assessment of the normal
pelvis, Siebenrock et al55 demonstrated a correlation between
pelvic tilt and acetabular version. At 9° of pelvic inclination,
all specimens demonstrated positive crossover and posterior
wall signs despite a lack of acetabular retroversion. This study
exposed the need for standardized techniques in radiographic
imaging to account for this variability. Furthermore, in a recent
retrospective study, Nepple et al47 found that coxa profunda,
a commonly accepted radiographic finding demonstrating
global acetabular overcoverage, should be considered a normal
radiographic finding in women.
Computed Tomography and 3-dimensional
Inaccurate or inconclusive preoperative assessment of plain
radiographs can lead to inadequate or excessive resection of
presumed lesions contributing to FAI. Failure to adequately
address the offending 3-dimensional (3D) deformity causing
FAI is the most common reason for failed arthroscopy and
need for revision.29,52 High-resolution CT allows for precise
evaluation of osseous morphology about the hip joint (Figure
1). Three-dimensional modeling is a recent advancement that
has demonstrated promise with regard to dynamic hip analysis
for preoperative planning (Figure 2). Using a noninvasive 3D
CT-based kinematic technique to create a virtual hip model,
Kubiak-Langer et al35 were able to identify the location of
impingement and assess the changes in range of motion before
and after virtual resection of isolated cam, pincer, or combined
lesions. Similarly, Bedi et al9 performed patient-specific 3D CT
modeling of hips with cam and/or pincer deformities. Models were
dynamically assessed for location and extent of impingement.
The location of impingement was unique in each case and did
not correlate with radiographic imaging. Virtual acetabular rim
trimming and/or femoral head-neck osteochondroplasty was
performed to remove areas of impingement, which improved hip
kinematics and range of motion.9
Dynamic 3D CT modeling may also help decipher deformities
that are symptomatic from those that are asymptomatic. Two
recent studies demonstrated the prevalence of cam-type
deformities in asymptomatic individuals. In an evaluation of
200 asymptomatic volunteers who underwent MRI, Hack
Figure 1. Three-dimensional computed tomography scan
demonstrating combined cam and pincer deformities.
Gupta et al Mar • Apr 2014
55. Siebenrock KA, Kalbermatten DF, Ganz R. Effect of pelvic tilt on acetabular
retroversion: a study of pelves from cadavers. Clin Orthop Relat Res.
Siebenrock KA, Schoeniger R, Ganz R. Anterior femoro-acetabular
impingement due to acetabular retroversion: treatment with
periacetabular osteotomy. J Bone Joint Surg Am. 2003;85:278-
Smith MV, Panchal HB, Ruberte Thiele RA, Sekiya JK. Effect of acetabular
labrum tears on hip stability and labral strain in a joint compression model.
Am J Sports Med. 2011;39:103S-110S.
58. Tannast M, Kubiak-Langer M, Langlotz F, Puls M, Murphy SB, Siebenrock
KA. Noninvasive three-dimensional assessment of femoroacetabular
impingement. J Orthop Res. 2007;25:122-131.
Walker JA, Pagnotto M, Trousdale RT, Sierra RJ. Preliminary pain and
function after labral reconstruction during femoroacetabular impingement
surgery. Clin Orthop Relat Res. 2012;470:3414-3420.
Zingg PO, Ulbrich EJ, Buehler TC, Kalberer F, Poutawera VR, Dora C.
Surgical hip dislocation versus hip arthroscopy for femoroacetabular
impingement: clinical and morphological short-term results. Arch Orthop
Trauma Surg. 2013;133:69-79.
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