Extrinsic radiocarpal ligaments: magnetic resonance imaging of normal wrists and scapholunate dissociation.

OBJECTIVE

To determine whether magnetic resonance imaging [MRI] in planes of imaging parallel to the known course of the extrinsic radiocarpal ligaments of the wrist aids in the visualization of these structures.

SUBJECTS AND METHODS

MRI was performed on 32 wrists: a single normal cadaveric wrist, 23 normal wrists in volunteers and 8 wrists in patients with known scapholunate dissociation and rotatory scaphoid subluxation. Proton-density and T2-weighted images were obtained in the sagittal plane and gradient recalled echo images in an oblique sagittal plane, selected to parallel the extrinsic radiocarpal ligaments. The images were interpreted by two musculoskeletal radiologists. Each of the six main extrinsic ligaments was assessed for visualization or nonvisualization, and the morphologic features of those visualized were documented.

RESULTS

With the exception of the dorsal radioscaphoid ligament, the volar and dorsal extrinsic radiocarpal ligaments were all consistently visualized in the normal wrists. For the eight cases of scapholunate dissociation, MRI demonstrated underlying rupture or thickening of the volar radioscaphocapitate ligament in all wrists and of the dorsal radiolunate ligament in five.

CONCLUSION

MRI in the true and oblique sagittal planes can consistently demonstrate the extrinsic radiocarpal ligaments of the wrist. With this technique, extrinsic ligamentous abnormality can be demonstrated in patients with scapholunate dissociation and rotatory scaphoid subluxation.