Intraoperative Guidance for the Surgical Correction of Cam Deformities Using Hip Arthroscopy Based on Alpha Angle Measurement.

Residual femoroacetabular impingement syndrome due to incomplete resection of a cam deformity is the leading cause of failed hip arthroscopy. The reliability of the alpha angle has been shown for quantifying cam deformities in femoroacetabular impingement syndrome. An intraoperative navigation tool that provides the ability to compare alpha angle measurements side by side on pre- and post-resection fluoroscopic images has recently been introduced. This tool uses fluoroscopic images obtained in 6 different hip positions. The reliability of these standardized hip positions has been shown by correlation with computed tomography in localization and visualization of cam deformities. The purpose of this Technical Note is to give technical tips about the application of this tool.