Preoperative Three-dimensional CT Predicts Intraoperative Findings in Hip Arthroscopy

Currently, plain radiographs and MRI are the standard imaging modalities used for diagnosing femoroacetabular impingement (FAI) and preoperative planning for arthroscopic treatment of FAI. The value of three-dimensional (3D) CT for these purposes is unclear. We therefore determined the reliability of CT assessment of FAI and whether CT findings of hip disease predict arthroscopic findings. We retrospectively assessed the preoperative CT scans of 118 patients who underwent primary hip arthroscopy. Intraoperative findings, including size of the cam lesion, presence of an acetabular labral articular disruption lesion, and one of four types of labral tear were recorded and compared with the retrospectively read CT findings. Agreement analysis between CT and intraoperative detection of FAI yielded kappa values of 0.48 for cam lesions and 0.16 for pincer lesions. Increasing values for the CT-based alpha angle correlated with increasing severity of arthroscopically assessed acetabular labral articular disruption grade. Each pattern of FAI predicted a specific labral tear type. Our data suggest CT has moderate value in predicting mechanically based labral tear patterns, although better parameters for assessment of pincer lesions are needed. Diagnostic assessment of patients with suspected FAI may be improved with use of 3D CT. Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.