Imaging of Carpal Instability

Imaging plays a vital role in the workup of patients with suspected carpal instability. Initial evaluation should always include radiographs, which can demonstrate fractures and carpal malalignment. CT is able to show fractures and subluxation of the carpal bones, and 3D CT images can be very helpful for pre-surgical planning. 3 T MRI provides high resolution images of the intrinsic and extrinsic carpal ligaments and is excellent at showing occult fractures or osseous contusions that may be missed on CT. CT arthrography and MR arthrography both have a high diagnostic accuracy in the detection of carpal ligamentous injuries and are important considerations when higher strength MRI scanners are not available. Ultrasound is able to show injury to the dorsal fibers of the scapholunate ligament, and dynamic ultrasound may be used to detect early scapholunate instability. However, ultrasound is less well suited for ligamentous injuries to other carpal ligaments. This chapter will review the imaging findings of the different types of carpal instability and stress the advantages and disadvantages of the different imaging modalities available to evaluate instability at the wrist.