Femoroacetabular impingement

The femoroacetabular conflict or “impingement” of the hip, results from an abnormal contact between the femoral head and the acetabular cavity or between the head-neck junction and the labrum.

It is usually associated with:

• Existence of a non-spherical sector in the transition between the head-neck junction and the head of the femur. Can cause chronic compression of the peripheral cartilage and cause severe lesions, even in young people. This morphology is the source of the impingement type "cam", more frequent in males and usually symptomatic in the 2nd or 3rd decade of life (fig. 1 + vid)

Fig.1: Hips with abnormal femoral head sphericity, there is a marked compression effect of cartilage and chondro-labral junction that can be harmful to the joint.

• Excess global acetabular coverage. Is found where there is a deep socket (see section "How to diagnose femoroacetabular impingement?"), or in case of an acetabular with retroversion. In these types of morphology there is an abnormal compression of the anterior labrum or more rarely posterior by the femoral neck, causing the so called “pincer” type femoroacetabular impingement. (fig. 2 + vid). This type appears more in females, usually in the 4th decade of life. Often there is a combination of all these conditions in the same hip, requiring an individualized approach in diagnosis and treatment.
   

Fig.2: In the case of effect "pincer" a significant compression of the labrum occurs, which usually degenerates and loses its elastohydrodynamic function. There may be a subluxation phenomena, particularly in situations of extreme mobility (classical dance).

Though this pathology results from morphological changes occurring during growth of the hip in infancy and youth, often early symptoms develop only after age of 20.

Athletes doing sports that involve significant hip mobility (martial arts, soccer, rhythmic gymnastics, dance and other) are at particular risk of developing symptoms of femoroacetabular impingement. The most frequent complaints are inguinal pain (groin) and / or trochanteric (lateral hip), manifested initially after sport. Later, pain may progress to activities considered to be routine. Normally, there is a pattern of gait claudication (limping), except in severe deformities. There is typically a decrease in internal rotation in flexion. Although it is not absolutely proven that the hips with femoroacetabular impingement always evolve to arthrosis, there seems to be an increased risk, specially associated with excessive mobility. Many cases of "pubalgia" in the athlete may be associated with femoroacetabular impingement.