CAM-Type Femoroacetabular Impingement

Demographic and clinical details: 32 years old male, with a bilateral hip pain

Image Details; AP radiograph of pelvis shows asphericity of the bilateral femoral head (pistol grip deformity) (white arrows). Aspherical femoral head shape which gives the appearance of a “pistol grip “deformity (b) is a typical radiographic sign of cam-type femoroacetabular impingement (FAI). Axial T1W images through cranial acetabulum on the first axial image that includes the femoral head shows the anterior rim of acetabulum lying medial to the posterior rim (black arrows) consistent with normal acetabular anteversion which excludes the pincer type of FAI.(Illustration (b)was drawn by Dr.Gokce Annac)

FAI, which causes mechanical hip pain, is characterized by early pathologic contact of the proximal femur with the acetabulum. FAI is classified as pincer-type,  cam-type and mixed type in which both  pincer and cam-type coexists. Cam-type of FAI is characterized by an aspherical femoral head that leads to a decrease in the femoral head neck offset. FAI is an important cause of early hip osteoarthritis. Early diagnosis and treatment of FAI can prevent progression of hip joint osteoarthritis. Iimpingement  syndromes is a clinical diagnosis, radiological examinations are helpful in revealing the auxiliary findings of impingement syndromes.

In my experience, Plain radiographies are important for determination of pistol grip deformity that is helpful for  the diagnosis of cam- type FAI. The diagnosis of impingement sydromes should be established by clinical examination findings.