Femoroacetabular impingement: Difference between revisions

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== Femoroacetabular Impingement ==
{{SI}}
 
{{Infobox medical condition
[[File:FAI.theora.ogv|thumb|right|Video explaining femoroacetabular impingement]]
| name            = Femoroacetabular impingement
 
| synonyms        = FAI
| specialty      = [[Orthopedic surgery]]
| symptoms        = [[Hip pain]], [[stiffness]], [[limitation of movement]]
| complications  = [[Osteoarthritis]]
| onset          = Typically [[young adults]]
| duration        = Chronic
| causes          = Abnormal contact between the [[femur]] and [[acetabulum]]
| risks          = [[Athletic activities]], [[genetic predisposition]]
| diagnosis      = [[Physical examination]], [[X-ray]], [[MRI]]
| differential    = [[Hip dysplasia]], [[labral tear]], [[osteoarthritis]]
| prevention      = Avoidance of activities that exacerbate symptoms
| treatment      = [[Physical therapy]], [[arthroscopic surgery]]
| medication      = [[NSAIDs]]
| prognosis      = Variable, depending on severity and treatment
| frequency      = Common in [[athletes]]
}}
'''Femoroacetabular impingement''' (FAI) is a condition involving abnormal contact between the [[femur]] and the [[acetabulum]] of the [[hip joint]], which can lead to joint damage and pain. This condition is often seen in young and active individuals and can be a precursor to [[osteoarthritis]] of the hip.
'''Femoroacetabular impingement''' (FAI) is a condition involving abnormal contact between the [[femur]] and the [[acetabulum]] of the [[hip joint]], which can lead to joint damage and pain. This condition is often seen in young and active individuals and can be a precursor to [[osteoarthritis]] of the hip.
== Types of Impingement ==
== Types of Impingement ==
FAI is generally classified into three types:
FAI is generally classified into three types:
=== Cam Impingement ===
=== Cam Impingement ===
[[File:X-ray_of_cam.jpg|thumb|left|X-ray showing cam impingement]]
[[File:X-ray_of_cam.jpg|left|thumb|X-ray showing cam impingement]]
Cam impingement occurs when the femoral head is not perfectly round and cannot rotate smoothly inside the acetabulum. This results in abnormal contact and damage to the cartilage and labrum.
Cam impingement occurs when the femoral head is not perfectly round and cannot rotate smoothly inside the acetabulum. This results in abnormal contact and damage to the cartilage and labrum.
=== Pincer Impingement ===
=== Pincer Impingement ===
[[File:X-ray_of_pincer_impingement.jpg|thumb|right|X-ray showing pincer impingement]]
[[File:X-ray_of_pincer_impingement.jpg|left|thumb|X-ray showing pincer impingement]]
Pincer impingement is characterized by excessive coverage of the femoral head by the acetabulum. This can lead to the labrum being pinched between the acetabulum and the femoral head.
Pincer impingement is characterized by excessive coverage of the femoral head by the acetabulum. This can lead to the labrum being pinched between the acetabulum and the femoral head.
=== Combined Impingement ===
=== Combined Impingement ===
In many cases, individuals may have a combination of both cam and pincer impingement, leading to a more complex clinical presentation.
In many cases, individuals may have a combination of both cam and pincer impingement, leading to a more complex clinical presentation.
== Diagnosis ==
== Diagnosis ==
Diagnosis of FAI typically involves a combination of clinical examination and imaging studies.
Diagnosis of FAI typically involves a combination of clinical examination and imaging studies.
=== Clinical Examination ===
=== Clinical Examination ===
Patients often present with hip or groin pain, especially during activities that involve hip flexion. A thorough physical examination can reveal limited range of motion and pain during specific movements.
Patients often present with hip or groin pain, especially during activities that involve hip flexion. A thorough physical examination can reveal limited range of motion and pain during specific movements.
=== Imaging Studies ===
=== Imaging Studies ===
==== X-rays ====
==== X-rays ====
X-rays are commonly used to assess the bony structures of the hip and identify signs of FAI.
X-rays are commonly used to assess the bony structures of the hip and identify signs of FAI.
==== Center-Edge Angle ====
==== Center-Edge Angle ====
[[File:Center-edge_angle_of_Wiberg.jpg|thumb|left|Diagram showing the center-edge angle of Wiberg]]
[[File:Center-edge_angle_of_Wiberg.jpg|left|thumb|Diagram showing the center-edge angle of Wiberg]]
The center-edge angle of Wiberg is used to assess the coverage of the femoral head by the acetabulum.
The center-edge angle of Wiberg is used to assess the coverage of the femoral head by the acetabulum.
==== Crossing Sign ====
==== Crossing Sign ====
[[File:Crossing_ratio_of_the_hip.jpg|thumb|right|Diagram showing the crossing sign of the hip]]
[[File:Crossing_ratio_of_the_hip.jpg|left|thumb|Diagram showing the crossing sign of the hip]]
The crossing sign is an indicator of acetabular retroversion, which can be associated with pincer impingement.
The crossing sign is an indicator of acetabular retroversion, which can be associated with pincer impingement.
==== Alpha Angle ====
==== Alpha Angle ====
[[File:Alpha_angle_measured_in_45_degrees_Dunn_view.jpg|thumb|left|Diagram showing the alpha angle in a 45-degree Dunn view]]
[[File:Alpha_angle_measured_in_45_degrees_Dunn_view.jpg|left|thumb|Diagram showing the alpha angle in a 45-degree Dunn view]]
The alpha angle is used to quantify the asphericity of the femoral head-neck junction, which is indicative of cam impingement.
The alpha angle is used to quantify the asphericity of the femoral head-neck junction, which is indicative of cam impingement.
==== Hip Offset Percentage ====
==== Hip Offset Percentage ====
[[File:Hip_offset_percentage_measured_in_cross-lateral_view.jpg|thumb|right|Diagram showing hip offset percentage]]
[[File:Hip_offset_percentage_measured_in_cross-lateral_view.jpg|left|thumb|Diagram showing hip offset percentage]]
The hip offset percentage is a measure used to evaluate the lateralization of the femoral head.
The hip offset percentage is a measure used to evaluate the lateralization of the femoral head.
==== Tönnis Angle ====
==== Tönnis Angle ====
[[File:Tönnis_angle_of_the_hip.jpg|thumb|left|Diagram showing the Tönnis angle of the hip]]
[[File:Tönnis_angle_of_the_hip.jpg|left|thumb|Diagram showing the Tönnis angle of the hip]]
The Tönnis angle is used to assess the inclination of the acetabulum.
The Tönnis angle is used to assess the inclination of the acetabulum.
== Treatment ==
== Treatment ==
Treatment for FAI can be conservative or surgical, depending on the severity of the condition and the patient's symptoms.
Treatment for FAI can be conservative or surgical, depending on the severity of the condition and the patient's symptoms.
=== Conservative Management ===
=== Conservative Management ===
Conservative treatment includes activity modification, physical therapy, and non-steroidal anti-inflammatory drugs (NSAIDs) to manage pain and improve hip function.
Conservative treatment includes activity modification, physical therapy, and non-steroidal anti-inflammatory drugs (NSAIDs) to manage pain and improve hip function.
=== Surgical Intervention ===
=== Surgical Intervention ===
Surgical options, such as hip arthroscopy, aim to correct the bony abnormalities and repair any damage to the labrum or cartilage.
Surgical options, such as hip arthroscopy, aim to correct the bony abnormalities and repair any damage to the labrum or cartilage.
 
== See also ==
== Related Pages ==
* [[Hip joint]]
* [[Hip joint]]
* [[Osteoarthritis]]
* [[Osteoarthritis]]
* [[Hip arthroscopy]]
* [[Hip arthroscopy]]
{{Medical conditions}}
{{Medical conditions}}
[[Category:Orthopedic conditions]]
[[Category:Orthopedic conditions]]
[[Category:Hip disorders]]
[[Category:Hip disorders]]

Latest revision as of 15:39, 6 April 2025

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD's medical weight loss NYC, sleep center NYC
Philadelphia medical weight loss and Philadelphia sleep clinics

Femoroacetabular impingement
Synonyms FAI
Pronounce N/A
Specialty Orthopedic surgery
Symptoms Hip pain, stiffness, limitation of movement
Complications Osteoarthritis
Onset Typically young adults
Duration Chronic
Types N/A
Causes Abnormal contact between the femur and acetabulum
Risks Athletic activities, genetic predisposition
Diagnosis Physical examination, X-ray, MRI
Differential diagnosis Hip dysplasia, labral tear, osteoarthritis
Prevention Avoidance of activities that exacerbate symptoms
Treatment Physical therapy, arthroscopic surgery
Medication NSAIDs
Prognosis Variable, depending on severity and treatment
Frequency Common in athletes
Deaths N/A


Femoroacetabular impingement (FAI) is a condition involving abnormal contact between the femur and the acetabulum of the hip joint, which can lead to joint damage and pain. This condition is often seen in young and active individuals and can be a precursor to osteoarthritis of the hip.

Types of Impingement[edit]

FAI is generally classified into three types:

Cam Impingement[edit]

X-ray showing cam impingement

Cam impingement occurs when the femoral head is not perfectly round and cannot rotate smoothly inside the acetabulum. This results in abnormal contact and damage to the cartilage and labrum.

Pincer Impingement[edit]

X-ray showing pincer impingement

Pincer impingement is characterized by excessive coverage of the femoral head by the acetabulum. This can lead to the labrum being pinched between the acetabulum and the femoral head.

Combined Impingement[edit]

In many cases, individuals may have a combination of both cam and pincer impingement, leading to a more complex clinical presentation.

Diagnosis[edit]

Diagnosis of FAI typically involves a combination of clinical examination and imaging studies.

Clinical Examination[edit]

Patients often present with hip or groin pain, especially during activities that involve hip flexion. A thorough physical examination can reveal limited range of motion and pain during specific movements.

Imaging Studies[edit]

X-rays[edit]

X-rays are commonly used to assess the bony structures of the hip and identify signs of FAI.

Center-Edge Angle[edit]

Diagram showing the center-edge angle of Wiberg

The center-edge angle of Wiberg is used to assess the coverage of the femoral head by the acetabulum.

Crossing Sign[edit]

Diagram showing the crossing sign of the hip

The crossing sign is an indicator of acetabular retroversion, which can be associated with pincer impingement.

Alpha Angle[edit]

Diagram showing the alpha angle in a 45-degree Dunn view

The alpha angle is used to quantify the asphericity of the femoral head-neck junction, which is indicative of cam impingement.

Hip Offset Percentage[edit]

Diagram showing hip offset percentage

The hip offset percentage is a measure used to evaluate the lateralization of the femoral head.

Tönnis Angle[edit]

Diagram showing the Tönnis angle of the hip

The Tönnis angle is used to assess the inclination of the acetabulum.

Treatment[edit]

Treatment for FAI can be conservative or surgical, depending on the severity of the condition and the patient's symptoms.

Conservative Management[edit]

Conservative treatment includes activity modification, physical therapy, and non-steroidal anti-inflammatory drugs (NSAIDs) to manage pain and improve hip function.

Surgical Intervention[edit]

Surgical options, such as hip arthroscopy, aim to correct the bony abnormalities and repair any damage to the labrum or cartilage.

See also[edit]