Editorial Commentary: Cam Femoroacetabular Impingement Requires Dynamic Assessment of Beta-Angle (Femoroacetabular Excursion Angle) and Consideration of Femoral and Acetabular Version: Cam Impingement in Patients With Acetabular or Femoral Retroversion May Warrant Greater Osteoplasty.

Abstract

Radiographs, magnetic resonance imaging, and computed tomography scans have been commonly used to evaluate femoroacetabular impingement (FAI) and are well accepted forms of surgical planning. Assessing and addressing both the femoral and acetabular sides result in a combination of "one-sided" treatments that, in sum, net a successful treatment of FAI. However, combining one-sided approaches may not consider the dynamic interaction of the femoral head with the acetabulum. Elevated alpha angles alone can be indicative of a cam-type lesion without necessitating the presence of functional FAI. The presence of a cam-type lesion on lateral radiographs, as suggested by a positive alpha angle, does not necessitate a decrease in clearance between the femoral head and acetabular rim as measured by the beta angle. Assessment of the beta angle, or femoroacetabular excursion angle, has the potential to address dynamic nature of FAI more accurately by directly measuring the degree of clearance between the femoral head and acetabulum. In addition, a comprehensive assessment of physical examination findings, particularly range of motion, as well as a summation of acetabular and femoral version (as measured by the McKibbin Index), are required. Cam-type of FAI poses a larger challenge in the patient with acetabular or femoral retroversion, which may warrant greater and more localized osteoplasty, distally, during hip arthroscopy.