IMPORTANT: We currently have a number of bugs related to image cropping and are actively trying to resolve them. In the meantime, we have disabled cropping. Apologies for any inconvenience. Stay informed: radiopaedia.org/chat

Femoroacetabular impingement - pincer-type

Case contributed by Domenico Nicoletti
Diagnosis almost certain

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.

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.