Usefulness of Radial Contrast-Enhanced Computed Tomography for the Diagnosis of Acetabular Labrum Injury

Purpose: The purpose of this study was to evaluate the usefulness of radial contrast-enhanced computed tomography (CT) in the diagnosis of acetabular labrum injury. Methods: We studied 21 hip joints in 21 patients (8 joints in 8 male patients and 13 joints in 13 female patients), aged between 16 and 81 years (mean, 43 years) at examination, who underwent both radial contrast-enhanced CT and hip arthroscopy. Plain radiography showed no abnormalities in the bone and joint in 19 joints and acetabular dysplasia in 2 joints. When we performed radial contrast-enhanced CT, a mixture of 5 mL of 2% lidocaine chloride and 10 mL of 64% iotrolan was injected intra-articularly under x-ray fluoroscopy. CT was conducted with a 4-slice multidetector CT system operated at a voltage of 120 kilovolt peak, current of 300 mA, collimation beam of 2 mm, field of view of 320 mm, slice thickness of 0.5 mm, table speed of 44 mm/s, and helical pitch of 5.5. Images were reconstructed by computer software for radial slices at 15° intervals perpendicular to the labral rim. The mean interval between the CT scan and arthroscopy was 13.2 days. Results: By contrast-enhanced CT, acetabular labrum tears were observed in 12 joints, loss of acetabular labrum was found in 1 joint, and no abnormalities were present in 8 joints. By arthroscopy, acetabular labrum tears were observed in 13 joints, loss of acetabular labrum was found in 1 joint, and no abnormalities were present in 7 joints. When the results of the 2 methods were compared, 12 joints had true-positive findings, 8 joints had true-negative findings, and 1 joint had a false-negative finding. Therefore contrast-enhanced CT had a sensitivity of 92.3%, specificity of 100%, and accuracy of 95.2%. Conclusions: The sensitivity, specificity, and accuracy of radial contrast-enhanced CT for the diagnosis of acetabular labrum injury are 92.3%, 100%, and 95.2%, respectively. We recommend radial contrast-enhanced CT for the diagnosis of acetabular labrum injury in patients in whom magnetic resonance imaging is contraindicated. Level of Evidence: Level IV, diagnostic study.

Key Words: Hip, Labrum tear, Computed tomography, Arthroscopy