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Femoroacetabular impingement - pincer-type

Case contributed by Dr Domenico Nicoletti

Presentation

Constrictive pain to the proximal portion of the left thigh.

Patient Data

Age: 30 years
Gender: Male

Typical signs of pincer-type femoroacetabular impingement anatomy:

  • The crossover sign is reflected in the AP projection with an overhanging anterior acetabular margin. The anterior and posterior walls of the acetabulum projectionally intersect midway over the femoral head creating a "figure of 8" appearance.
  • There is prominently seen ischial spines indicating acetabular retroversion. These are normally not visible on anterior-posterior radiographs.
Annotated image

Typical signs of pincer-type femoroacetabular impingement anatomy:

  • The crossover sign is reflected in the AP projection with an overhanging anterior acetabular margin. The anterior and posterior walls of the acetabulum projectionally intersect midway over the femoral head creating a "figure of 8" appearance.
  • There is prominently seen ischial spines indicating acetabular retroversion. These are normally not visible on anterior-posterior radiographs.

Case Discussion

This is a case of femoroacetabular impingement (FAI) due to anterior acetabular wall overcoverage, which encounters the femoral neck early with end range of motion. The term "pincer” comes from the acetabulum pinching on the proximal femur.

The pincer effect may be due to a partial acetabular retroversion, acetabular overcoverage with or without coxa profunda, in which the head of the femur is fully covered by the acetabulum.

Impingement type can be congenital, developmental or acquired. In the latter case can be the outcome of a periacetabular osteotomy or fracture.

Pincer-type FAI more often occurs in women.

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Case information

rID: 43886
Published: 27th Mar 2016
Last edited: 18th Nov 2019
Inclusion in quiz mode: Included

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