Femoroacetabular Impingement

Hip Preservation and Femoroacetabular Impingement (FAI)

Femoroacetabular impingement (FAI) is also known as a hip impingement. The first part of the term refers to the ball on top of the femur (thighbone) that sits in the acetabulum (hip socket); the second part means tissue in that joint is pinched, causing pain.

FAI occurs when there is an abnormal amount of bone on either the ball of the thighbone or in the socket. The extra bone can cause tears to the soft tissue, which, over time, wears down the protective tissue around the bone called cartilage. When this happens, the bones rub together, causing pain, limited function and possibly early arthritis.

FAI first appears in the early teen years through adulthood, and can be present in either hip.

Causes of FAI

FAI develops when the hipbones fail to form normally and have activity beyond the limit of what they can tolerate. The exact causes of abnormal hip joint development are multifactorial.

FAI sometimes develops after someone has had Legg-Calve-Perthes (LCP) disease, slipped capital femoral epiphysis (SCFE), or other related pediatric diseases of the hip.

Although FAI is not directly caused by exercise, it can develop in growing children due to increased activity. There is evidence it is related to activity.

FAI and AHD (adolescent hip dysplasia) are often seen together in patients.

Signs and Symptoms of FAI

FAI may not be noticed early on if it is very mild and does not cause any symptoms.

FAI symptoms include:

  • Trouble participating in sports or recreational activities due to hip pain or fatigue
  • Increasing pain in the hip or groin
  • Trouble sitting or riding in a car for long periods of time
  • Interruption of normal everyday activities due to pain
  • Poor endurance
  • Hip joint catching or locking
  • A limp or change in how the person walks
  • A difference in the length of each leg

Symptoms can range from mild to severe and usually worsen over time.

Diagnosis of FAI

Doctors perform a physical exam to diagnose FAI. To rule out other conditions and better view the hip anatomy, they may also include one or more of the following:

  • X-ray
  • MRI (magnetic resonance imaging)
  • CT (computed tomography) scan

Types of FAI

The four types of FAI are:

  • Pincer, where too much bone exists at the edge of the hip socket
  • Cam, where too much bone is on the ball of the hip
  • Combined, where both pincer and cam impingements are present
  • Femoral torsion, specifically retrotorsion

Treatment of FAI

Treatment varies depending on the severity of FAI. The care team at Cincinnati Children’s, tailors treatment to each patient. Treatment can include:

  • Adjusting levels of activity
  • Physical therapy
  • Anti-inflammatory medications
  • Surgery (see different types described below)

Hip arthroscopy is a surgical treatment for the hip joint. The goal is to correct the abnormal bone growth on the hip joint. To do this, the surgeon makes small incisions at the hip. Through these incisions, the surgeon will reshape the bones and/or repair tears to the cartilage. More severe cases of FAI might need an open surgery that requires a larger incision.

Our surgeons have specialized training in both types of surgery used to treat FAI and perform these procedures routinely.

At Cincinnati Children’s, we treat patients with FAI ranging in age from the early teens up to the early 40s. We treat adults with this condition because FAI starts during childhood and we have extensive experience managing it over a lifetime.

Recovery from Surgery for FAI

Recovery depends upon the amount of damage found in the hip joint and the type of procedure performed. After hip surgery, the patient will need crutches for one to two weeks. For teen and adult patients, rehabilitation after surgery typically involves four to six months of physical therapy. Exercises help strengthen the hip joint and prepare the hip to carry weight again. Individuals often return to selected activities in four to six months.

What Is the Long-Term Outlook for Children with FAI?

If symptoms are left untreated, FAI will cause injury to the hip. This can lead to more pain, decreased function and the possible development of osteoarthritis. Over time, chances that the joint will worsen quickly increase. If this happens, the patient may need a total hip replacement. With treatment, patients are commonly able to return to prior activities with less pain.

For patients undergoing surgery, the long-term results of hip surgery are very good. Both arthroscopic and open surgery typically result in improved hip function with less pain in even the most severe cases. Results can vary depending on how severe the disease is and the expectations of the patient.

FAI is a leading cause of arthritis in adults and some patients may develop arthritis later in life. Others may need a hip replacement in the future, depending on how bad the FAI was at the time of surgery.

Last Updated 05/2020

Reviewed by Patrick Whitlock, MD, PhD, and Rachel Breitenstein, APRN

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