It is a condition of too much friction in theIt is a condition of too much friction in the
hip joint. Basically, the femoral head andhip joint. Basically, the femoral head and
acetabulum rub abnormally creatingacetabulum rub abnormally creating
damage to the hip joint. The damage candamage to the hip joint. The damage can
occur to the articular cartilage or the labraloccur to the articular cartilage or the labral
Activities CAUSING FAIActivities CAUSING FAI
Ice HockeyIce Hockey
Horseback RidingHorseback Riding
Football (American)Football (American)
Field HockeyField Hockey
Bike Riding/CyclingBike Riding/Cycling
Martial ArtsMartial Arts
Deep squatting activities such as power liftingDeep squatting activities such as power lifting
Significant athletic activity before skeletalSignificant athletic activity before skeletal
maturity increases the risk of FAI.maturity increases the risk of FAI.
Prior Biomechanical theories suggest thatPrior Biomechanical theories suggest that
cartilage damage is initiated by Concentric orcartilage damage is initiated by Concentric or
Eccentric overload.Eccentric overload.
- Eccentric overload- Eccentric overload
- easily explained by- easily explained by
non-congruent articulations caused bynon-congruent articulations caused by
developmental dysplasias and post-traumaticdevelopmental dysplasias and post-traumatic
- Concentric overload- Concentric overload
- not as easy to explain- not as easy to explain
Ganz et al. CORR. 2003Ganz et al. CORR. 2003
-- Summarized the concept of FAISummarized the concept of FAI
- Mechanism for development of- Mechanism for development of
osteoarthritis based on subtle aberrant bony morphologyosteoarthritis based on subtle aberrant bony morphology
-- Acetabular Retroversion / CoxaAcetabular Retroversion / Coxa
-- Femoral Head non-sphericityFemoral Head non-sphericity
-- Abnormal ContactAbnormal Contact in Normal / Nearin Normal / Near
Normal Appearing HipsNormal Appearing Hips
-- Abutment of the Proximal FemurAbutment of the Proximal Femur
on the Acetabular Rim during terminal motion of the hipon the Acetabular Rim during terminal motion of the hip
leading to lesions of the labrum and/or the adjacentleading to lesions of the labrum and/or the adjacent
-- Chondral and Labral lesionsChondral and Labral lesions progressprogress
and result in degenerative diseaseand result in degenerative disease
FAI FormsFAI Forms
Generally occurs as two Cam and Pincer.Generally occurs as two Cam and Pincer.
TheThe Cam formCam form (Cam comes from the(Cam comes from the
Dutch word meaning “cog”) describes theDutch word meaning “cog”) describes the
femoral head and neck relationship asfemoral head and neck relationship as
This loss of roundness contributes toThis loss of roundness contributes to
abnormal contact between the head andabnormal contact between the head and
CAM ImpingementCAM Impingement
- Abnormal Femoral Head/Neck- Abnormal Femoral Head/Neck
junction with increased radius at the waistjunction with increased radius at the waist
- Motion- Motion
- Impingement occurs primarily during- Impingement occurs primarily during
flexion, adduction, IRflexion, adduction, IR
- Contact between the femoral neck- Contact between the femoral neck
and acetabular rim induces compressionand acetabular rim induces compression
- Shear stress generated at the junction- Shear stress generated at the junction
between the labrum and the cartilage and at thebetween the labrum and the cartilage and at the
subchondral tidemarksubchondral tidemark
- Outward avulsion of the labrum- Outward avulsion of the labrum
and/or an inward compression of the articular cartilageand/or an inward compression of the articular cartilage
at Anterosuperior Rimat Anterosuperior Rim
Etiology of CAM ImpingementEtiology of CAM Impingement
- Elliptical Femoral Head- Elliptical Femoral Head
- Slipped Capital Femoral- Slipped Capital Femoral
Epiphysis -Epiphysis - SCFESCFE
-- Legg Calve PerthesLegg Calve Perthes
-- Adult OsteonecrosisAdult Osteonecrosis
- Malunited Femoral Neck- Malunited Femoral Neck
The Pincer FormThe Pincer Form
Pincer comes from the French word meaning “toPincer comes from the French word meaning “to
describes the situation where the socket ordescribes the situation where the socket or
acetabulum has too much coverage of femoralacetabulum has too much coverage of femoral
This over-coverage typically exists along theThis over-coverage typically exists along the
front-top rim of the acetabulum,front-top rim of the acetabulum,
results in the labral cartilage being “pinched”results in the labral cartilage being “pinched”
between the rim and the anterior femoral head-between the rim and the anterior femoral head-
neck junction.neck junction.
Pincer form of the ImpingementPincer form of the Impingement
Secondary to “retroversion”, or “profunda”,Secondary to “retroversion”, or “profunda”,
Most of the time, the Cam and PincerMost of the time, the Cam and Pincer
forms exist together.forms exist together.
Pincer ImpingementPincer Impingement
- Excessive Acetabular Coverage- Excessive Acetabular Coverage
- Motion- Motion
- Dependent on acetabular morphology- Dependent on acetabular morphology
- Linear Contact between the labrum and femoral- Linear Contact between the labrum and femoral
head/neck junctionhead/neck junction
- Anterior = Acetabular Retroversion- Anterior = Acetabular Retroversion
- Circumferential = Coxa Profunda- Circumferential = Coxa Profunda
- Force from the femoral neck is transferred through the- Force from the femoral neck is transferred through the
labrum to the acetabular cartilagelabrum to the acetabular cartilage Results is chronic degeneration ofResults is chronic degeneration of
anterior labrum and subsequent ossificationanterior labrum and subsequent ossification Further deepens theFurther deepens the
Resultant leverage of head in acetabulum with excessiveResultant leverage of head in acetabulum with excessive
ROM can result in contre-coup lesion in posteroinferior acetabulumROM can result in contre-coup lesion in posteroinferior acetabulum
and posteromedial femoral headand posteromedial femoral head
- Leading to Circumferential involvement- Leading to Circumferential involvement
- Acetabular Retroversion- Acetabular Retroversion
- Coxa Profunda- Coxa Profunda
- Protrusio Acetabuli- Protrusio Acetabuli
- Iatrogenic- Iatrogenic
overcorrection forovercorrection for
- Coxa Vara- Coxa Vara
- Os Acetabuli- Os Acetabuli
ASSOCIATED CARTILAGEASSOCIATED CARTILAGE
FAI is associated with cartilage damage,FAI is associated with cartilage damage,
labral tears,labral tears,
early hip arthritis,early hip arthritis,
sports hernias, andsports hernias, and
low back pain.low back pain.
FAI is common in high level athletes, butFAI is common in high level athletes, but
also occurs in active individualsalso occurs in active individuals
Most patients can be diagnosed with aMost patients can be diagnosed with a
good history,good history,
AA patient’s historypatient’s history ..
TheThe physical examphysical exam
TheThe plain x-rayplain x-ray filmsfilms
Gait should be closely scrutinized looking forGait should be closely scrutinized looking for
an abductor lurch,an abductor lurch,
a shortened stance phase,a shortened stance phase,
circumduction, or steppage.circumduction, or steppage.
Leg lengths should be measured using accurateLeg lengths should be measured using accurate
The patient's posture should be noted, includingThe patient's posture should be noted, including
examination of the back for scoliosis.examination of the back for scoliosis.
Anterior femoral-acetabularAnterior femoral-acetabular
the affected hip is flexed to ninty degrees and the leg isthe affected hip is flexed to ninty degrees and the leg is
internally rotated and adducted.internally rotated and adducted.
If there is abnormal contact between the anterior-If there is abnormal contact between the anterior-
superior acetabular rim and femoral neck, pain may besuperior acetabular rim and femoral neck, pain may be
Posterior impingement may be tested by having thePosterior impingement may be tested by having the
patient dangle their legs off the end of an examinationpatient dangle their legs off the end of an examination
with the affected leg externally rotated by the examiner,with the affected leg externally rotated by the examiner,
and the opposite limb held flexed by the patient. In aand the opposite limb held flexed by the patient. In a
positive exam, the femur contacts the posteriorpositive exam, the femur contacts the posterior
acetabular rim eliciting pain.acetabular rim eliciting pain.
The range of motionThe range of motion
A decreased range of motion of the hip,A decreased range of motion of the hip,
especially in cases of an external rotationespecially in cases of an external rotation
contracture, can point to an intra-articular causecontracture, can point to an intra-articular cause
of the pain.of the pain.
Patients with hip pathology often also develop aPatients with hip pathology often also develop a
flexion contracture. The Thomas test is a helpfulflexion contracture. The Thomas test is a helpful
A thorough neurovascular exam should beA thorough neurovascular exam should be
conducted to rule out spine and other neuralconducted to rule out spine and other neural
causes of the patient's pain.causes of the patient's pain.
The AP pelvis X-ray must be well centeredThe AP pelvis X-ray must be well centered
and well developed as to show a clearand well developed as to show a clear
outline of the acetabulum.outline of the acetabulum.
The coccyx should point toward theThe coccyx should point toward the
symphysis pubis, and there should besymphysis pubis, and there should be
about 1-2 cm between them.about 1-2 cm between them.
The anterior and posterior walls, the tearThe anterior and posterior walls, the tear
drop and the lateral edge of thedrop and the lateral edge of the
acetabulum should be noted.acetabulum should be noted.
may be taken to evaluate for hip dysplasiamay be taken to evaluate for hip dysplasia
including theincluding the Tönnis angleTönnis angle (abnormal < 10(abnormal < 10
the lateral center-edge angle of Wibergthe lateral center-edge angle of Wiberg
(abnormal < 25 degrees), and(abnormal < 25 degrees), and
thethe Anterior center-edge angle of LequesneAnterior center-edge angle of Lequesne
(abnormal < 25 degrees) as measured on a(abnormal < 25 degrees) as measured on a
false-profile radiograph.false-profile radiograph.
The neck shaft angleThe neck shaft angle of the proximal femur isof the proximal femur is
considered normal between 120 and 140considered normal between 120 and 140
Coxa ProfundaCoxa Profunda
When the floor of the acetabular fossa is inWhen the floor of the acetabular fossa is in
line with the ilioischial line;line with the ilioischial line;
Protrusio is present when the medial mostProtrusio is present when the medial most
femoral head overlaps the ilioischial line.femoral head overlaps the ilioischial line.
The crossover signThe crossover sign is a sensitive and specificis a sensitive and specific
indicator of native acetabular version.indicator of native acetabular version.
On anOn an AP pelvis radiographAP pelvis radiograph, the outlines of, the outlines of
the edges of the anterior and posterior wallsthe edges of the anterior and posterior walls
of the acetabulum should meet superiorlyof the acetabulum should meet superiorly
and laterally.and laterally.
COXA PROFUNDACOXA PROFUNDA
In cases ofIn cases of acetabular retroversionacetabular retroversion, this, this
crossover of the anterior and posteriorcrossover of the anterior and posterior
acetabular wall outlines is more distal.acetabular wall outlines is more distal.
Changes in the acetabular rim may alsoChanges in the acetabular rim may also
be noted.be noted.
AA 'double line'double line' is seen in labral' is seen in labral
AnAn os acetabulios acetabuli may also be an indicatormay also be an indicator
of pathologyof pathology
Alterations of the proximal femoral anatomy, such asAlterations of the proximal femoral anatomy, such as
head neck offset and bump formation can be observed inhead neck offset and bump formation can be observed in
addition to acetabular and labral pathology.addition to acetabular and labral pathology.
A pistol grip deformity of the femoral head is often seenA pistol grip deformity of the femoral head is often seen
in Cam Type impingement.in Cam Type impingement.
In this situation the superior-lateral head neck junction isIn this situation the superior-lateral head neck junction is
convex instead of concave.convex instead of concave.
A high fovea can also indicate asphericity of the femoralA high fovea can also indicate asphericity of the femoral
head that is not able to be appreciated on the AP films.head that is not able to be appreciated on the AP films.
A cross table lateral may show an abnormality in theA cross table lateral may show an abnormality in the
anterior head neck junction in cases of impingement.anterior head neck junction in cases of impingement.
The Alpha AngleThe Alpha Angle
Drawn on the AP pelvis radiograph, is formedDrawn on the AP pelvis radiograph, is formed
by a line drawn from the center of the femoralby a line drawn from the center of the femoral
head through the center of the femoral neck,head through the center of the femoral neck,
A line from the center of the femoral head toA line from the center of the femoral head to
the femoral head/neck junction, found by thethe femoral head/neck junction, found by the
point by which the femoral neck diverges from apoint by which the femoral neck diverges from a
circle drawn around the femoral head.circle drawn around the femoral head.
A normal patients' alpha angle is around 45A normal patients' alpha angle is around 45
whereas patients withwhereas patients with FemoroacetabularFemoroacetabular
impingement may be around 70 degrees.impingement may be around 70 degrees.
ALPHA ANGLEALPHA ANGLE
Often an MRI of the hip is used to confirmOften an MRI of the hip is used to confirm
a labral tear or damage to the jointa labral tear or damage to the joint
The MRI is most helpful in eliminatingThe MRI is most helpful in eliminating
certain causes of non FAI hip paincertain causes of non FAI hip pain
including avascular necrosis (dead bone)including avascular necrosis (dead bone)
and tumors.and tumors.
A course of non-operative treatment forA course of non-operative treatment for
most hip pathology may be tried first.most hip pathology may be tried first.
Patients presenting with femoroacetabularPatients presenting with femoroacetabular
impingement or labral disease may tryimpingement or labral disease may try
modification of activitymodification of activity
avoiding excessive hip movementavoiding excessive hip movement
regular non-steroidal anti-inflammatoryregular non-steroidal anti-inflammatory
Arthroscopic assessment of the hip can includeArthroscopic assessment of the hip can include
examination of both the central and peripheralexamination of both the central and peripheral
The central compartment includes the labrum and allThe central compartment includes the labrum and all
structures located further medially.structures located further medially.
Tearing of the labrum anterolaterally and damage to theTearing of the labrum anterolaterally and damage to the
acetabular cartilage is characteristic.acetabular cartilage is characteristic.
The lesions of the labrum and any areas of chondralThe lesions of the labrum and any areas of chondral
damage are debrided.damage are debrided.
Labral repair may be possible for specific tears.Labral repair may be possible for specific tears.
For areas of exposed subchondral bone a microfractureFor areas of exposed subchondral bone a microfracture
technique may be performed.technique may be performed.
SAFE Surgical Hip Dislocation-SAFE Surgical Hip Dislocation-
Surgical dislocation of the hip has been described.Surgical dislocation of the hip has been described.
A posterior incision (Kocher-Langenbeck) as this approachA posterior incision (Kocher-Langenbeck) as this approach
usually provides better access to posterior parts of the jointusually provides better access to posterior parts of the joint
after the hip is dislocated.after the hip is dislocated.
A trochanteric flip osteotomy is performed. The trochanter isA trochanteric flip osteotomy is performed. The trochanter is
osteotomized from a posterior to anterior direction, the cutosteotomized from a posterior to anterior direction, the cut
exits superficial to the piriformis fossa superiorly and at theexits superficial to the piriformis fossa superiorly and at the
vastus ridge inferiorly.vastus ridge inferiorly.
The gluteus minimus muscle is dissected carefully off theThe gluteus minimus muscle is dissected carefully off the
capsule starting at the piriformis interval.capsule starting at the piriformis interval.
The capsulotomy is Z-shaped (for the right hip), with theThe capsulotomy is Z-shaped (for the right hip), with the
superior limb located along the posterior acetabular rim, andsuperior limb located along the posterior acetabular rim, and
the inferior limb located at the level of the anteromedialthe inferior limb located at the level of the anteromedial
femoral neckfemoral neck
After dislocation of the hip, the acetabular labrum andAfter dislocation of the hip, the acetabular labrum and
the adjacent articular cartilage are assessed, and thethe adjacent articular cartilage are assessed, and the
identified lesions are tested for partial or completeidentified lesions are tested for partial or complete
avulsions from the acetabular rim.avulsions from the acetabular rim.
The severity, extent, and location of these lesions shouldThe severity, extent, and location of these lesions should
be defined, and their association with FAI should bebe defined, and their association with FAI should be
confirmed by provocative maneuvers in flexion andconfirmed by provocative maneuvers in flexion and
internal rotation with the head relocated.internal rotation with the head relocated.
The combination of anterior over coverage and theThe combination of anterior over coverage and the
status of the labrum and the acetabular articular cartilagestatus of the labrum and the acetabular articular cartilage
will determine the type of treatment of the acetabularwill determine the type of treatment of the acetabular
In cases of anterior over coverage contributing to FAI,In cases of anterior over coverage contributing to FAI,
as is frequent with acetabular retroversion, a resectionas is frequent with acetabular retroversion, a resection
osteoplasty of the anterosuperior rim is done.osteoplasty of the anterosuperior rim is done.
Periacetabular OsteotomyPeriacetabular Osteotomy
Reorientation of the articulating surfaces of theReorientation of the articulating surfaces of the
hip joint is an attractive procedure in the patienthip joint is an attractive procedure in the patient
with hip dysplasia.with hip dysplasia.
Increased joint congruity after reorientation ofIncreased joint congruity after reorientation of
the osteotomized fragment allows loadthe osteotomized fragment allows load
transmission through a broader area subjectedtransmission through a broader area subjected
to less pressure.to less pressure.
These changes can be expected to reduce painThese changes can be expected to reduce pain
and possibly protect the articular cartilage fromand possibly protect the articular cartilage from
degenerative changesdegenerative changes
Pelvic OsteotomyPelvic Osteotomy
Corrects the major anatomic abnormalityCorrects the major anatomic abnormality
and has the further advantage overand has the further advantage over
femoral osteotomy of not creating afemoral osteotomy of not creating a
secondary femoral deformity.secondary femoral deformity.
Femoral osteotomy may be added toFemoral osteotomy may be added to
pelvic osteotomy when coexistent femoralpelvic osteotomy when coexistent femoral
anatomic abnormalities are significant.anatomic abnormalities are significant.
Bernese Periacetabular OsteotomyBernese Periacetabular Osteotomy
The is indicated for patients with hipThe is indicated for patients with hip
symptoms of mechanical overload,symptoms of mechanical overload,
impingement, or hip instability as a resultimpingement, or hip instability as a result
of insufficient acetabular coverage.of insufficient acetabular coverage.