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What is FAI?    

What is Femoral Acetabular Impingement (FAI)?

  1. condition

Femoral acetabular impingement (FAI) has been identified as one of the causes of hip pain, hip labrum injury, cartilage injury, and early osteoarthritis1. In FAI, it is known that repeated impact between the femoral head/neck and the acetabular rim causes damage to the labrum and articular cartilage, and further induces arthropathic changes (OA). ing. 1 Minimally invasive treatment is desired, especially for athletes and sports enthusiasts, because pain and restricted range of motion result in decreased performance. In elite athletes, the frequency of bone morphology suggestive of FAI on X-rays is extremely high, 60% to 95%, compared to the general population. Until now, it was thought that only Europeans and Americans had this problem, but Japanese had few.

In athletes, impingement is likely to be induced in all sports activities, such as endurance sports such as track and field and triathlon, sports with many pivot movements such as basketball, martial arts, collision and contact sports. If you see an athlete who has complained of hip or groin pain, do so with caution.

Prior to the FAI report, the hip labrum was often treated only for its name. However, 87-90% of hip labrum injuries are thought to be caused by bone malformation such as impingement due to FAI or acetabular dysplasia, and treatment results are satisfactory even if only hip labrum injuries are treated. It should not be overlooked that FAI is an underlying disease, as there have been many reports of poor results.

  1. Diagnosis guidelines (from the Japan Hip Society)

Roentgenological diagnoses are divided into Pincer and Cam. Imaging findings suggestive of Pincer type FAI include (1) a CE angle of 40° or more, (2) a CE angle of 30° or more and an acetabular roof obligation (ARO) of 0° or less, and (3) a CE angle of 25° or more and a positive cross-over sign. Therefore, it is suggested that cases with a CE angle of 25° or less should be excluded from FAI as acetabular dysplasia.

Imaging findings suggestive of cam-type FAI include 2 or more of the following main items: alpha angle of 55° or more, sub-item Head-neck offset ration (less than 0.14), pistol grip deformation, and Herniation pit. mentioned.

It is necessary to measure each parameter of plain radiographs in detail.

Physical findings include a positive anterior impingement test (evaluating pain induction during hip flexion and internal rotation) and a decrease in the hip flexion and internal rotation angle. According to the diagnostic guidelines of the Japan Hip Society, cases that meet these imaging findings and have clinical symptoms are clinically judged as FAI. In addition, this is a diagnostic guideline for FAI in the narrow sense, excluding bone morphological abnormalities secondary to obvious hip joint diseases, and known hip joint diseases including hip joint trauma and a history of hip joint surgery are listed as exclusion items._cc781905-5cde -3194-bb3b-136bad5cf58d_

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