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 degrees 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.