All You Should Know About Femoroacetabular Impingement

Updated on June 9, 2022

Hip impingement or Femoroacetabular impingement (FAI) is a condition where the hip joint is abnormally shaped. Femoroacetabular impingement symptoms are experienced by a lot of people irrespective of their age. The condition makes the bones rub against each other, which can limit motion, and is painful as well.

What is Femoroacetabular impingement (FAI)?

The abnormally shaped hip joint causing bones to rub together is known as the Femoroacetabular impingement or FAI condition. When the bones in the hip joint rub against each other, the femur, or thigh bone, and acetabulum, or the part of the pelvic bone are affected. The worst symptom of FAI is limited movement and hip pain ranging from mild to severe depending on the impact of the condition.

Reasons behind Femoroacetabular impingement (FAI)

The hip joint is referred to as the ball-and-socket joint that links the femur to the pelvis bone. Individuals suffering from FAI have defects in the top of the femur or the socket joint. The defect or abnormality gives rise to friction during motion that can damage the nearby cartilage and the labrum area. The defects related to FAI are present at birth in the majority of the cases. The condition can also develop later in life, particularly during the teenage years.

Classification of FAI

Based on femoroacetabular impingement symptoms and causes, doctors classify the condition into three divisions.

1. Pincer

The category of FAI is caused due to the growth of extra bone in the hip socket. Bone growth often takes place during the growing and developing stage of a child’s life.

2. Cam

It occurs when there is bone growth located at the top of the femur. In certain cases, such growth results from extreme physical activities.

3. Combined

The third category is the combination of both pincer and cam FAI.

Individuals who are active physically will experience FAI pain symptoms earlier than those with inactive lifestyles. It is considered by doctors that in the majority of the FAI cases, workouts and exercises don’t result in the condition.

Common symptoms of FAI

In several cases, individuals don’t notice any symptoms. Signs of FAI start showing up when the damage in the hip joints is advanced and starts worsening. Some common signs and symptoms include:

·   Hip stiffness

·   Hip pain especially when sitting or standing for a long period

·   Limping


Several tests are used by doctors to diagnose Femoroacetabular Impingement. The doctor enquires about family medical history and levels of physical activities the patient engages in a day. To confirm the condition, the following diagnostic tools are used.

Imaging evaluation

Tests like MRIs and X-rays help doctors to recognize the signs of abnormalities and signs of hip joint damage.

Impingement tests

The doctor brings the knees of the patient up to his/her chest and then rotates toward the opposite shoulder. If the patient experiences pain with the movement, he/she is likely to have FAI.

Anesthetic injection (local)

When the doctor identifies FAI in a patient, he/she injects the affected hip joint with numbing medicine to assess whether it causes any pain relief.

Examining physically

When the doctor performs a complete physical examination, it helps him/her to determine the motion ranges, strength of muscles, and the style of walking. All such factors help to assess whether the hip joint is working properly.


Femoroacetabular impingement symptoms shouldn’t be ignored. Without treatment, it causes joint deterioration, and severe arthritis, and limits mobility to a greater extent. Thus, it is recommended to get medical attention at the earliest.

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