Hip impingement, or Femoro acetabular impingement (FAI)

Hip impingement, also known as femoro acetabular impingement (FAI) occurs when there is a deformity in one or both of the bones in the hip joint, causing friction in the joint. Over time, this friction or movement can cause cartilage tears in the labrum (the seal that lines the hip joint) and cartilage damage, causing pain and sometimes arthritis. 


There are two types of FAI: 


  1. Cam impingement (deformity of the thigh bone) happens when the abnormally shaped femoral head (ball) and head-neck junction jam into the hip socket during daily activities like bending, sitting for long periods of time, or riding a bike. 
  2. Pincer impingement happens when the hip socket is deep or is facing backwards. The femoral neck jams on the acetabular margin causing extensive labral tears and damage to the articular cartilage. Continued direct contact to the labrum and cartilage causes pain and arthritis.

 Most children have a combination of both types of FAI. When identified early, joint degeneration and arthritis can be prevented by early and timely intervention. Early results are encouraging in preventing arthritis and providing a pain free hip.


What can cause femoro acetabular impingement (FAI)?

  • Legg-Calvé-Perthes, which changes the shape of the ball and socket of the hip joint
  • Slipped Capital Femoral Epiphysis, which changes the shape of the femoral head and acetabulum
  • Repetitive motion of the hip (running, ice skating, weight lifting)
  • Extreme hip flexion (dance, gymnastics)
  • Trauma to the hip

Arthritis can often be prevented if the deformities leading to it are corrected before irreversible cartilage damage has been done. Most mechanical abnormalities in the hip can be treated if they are diagnosed correctly and fixed early enough with joint realignment (osteotomy) or bone trimming procedures.


What tests might my child need?

Special hip x-rays, CT scan and MRI may be required for evaluation of the problem and the status of the labrum and the cartilage.


What treatment options are available for children with FAI?

Treatment can be non-surgical or surgical depending on the symptoms, deformity and the expected damage in the joint.


Non-Surgical Treatment

These treatments include activity modification and physical therapy (to strengthen muscles), weight loss, and/or pain medication. Although they can alleviate some symptoms, the underlying abnormality is not corrected.


Surgical Treatment

Early and timely intervention can prevent further damage to the joint. The purpose of surgery is to correct a mechanical problem (such as FAI or hip dysplasia) with a mechanically based joint preservation surgery to provide pain relief and improve function and longevity of the hip joint. 


Hip Arthroscopy

Hip Arthroscopy is a minimally invasive technique for treating intraarticular problems in the hip such as mild to moderate FAI. The procedures include labral debridement, labral repair and/or shaving of the bone. 


Mini Arthrotomy 

Mini Arthotomy is a procedure in which the capsule surrounding the hip joint is opened. Mild FAI could be treated with shaving of the bone. Some labral tears can be repaired through this approach.


Surgical Hip Dislocation

Surgical Hip Disclocation is a more invasive procedure where the capsule surrounding the hip joint is opened and the femoral head is completely separated from the socket. This approach gives the best view of the femoral head and the socket. Procedures such as shaving of the bone from the head neck junction (osteoplasty), labral repair, trimming of a deep socket and/or microfracture of the damaged cartilage may be used to fix the dislocation.