about dynamic cone-beam ct imaging of TFCC wrist injury
It’s always difficult to combine clinical aspects and diagnostic imaging, approaching wrist joint pathology; in many circumstances the orthopaedic surgeon needs to directly visualize what’s happened during the joint motion, especially in a complex region such as the wrist.
I show you an example in which a complex tear of the triangular fibrocartilage complex (TFCC) is evident, togheter with a positive ulnar variance. TFCC is a complex of a fibrocartilaginous disk in association with several ligamentous structures, acting as a stabilizers of the distal radioulnar joint, and transmitting axial loading from carpus to the ulna.
Coronal T1w (left) and 3D SHARC (right) Mri scans (0.3 Tesla).
The dedicated Mri examination (0.3 Tesla), depicts the pathologic picture; the ulnar plus defines the reduction of the quadrilateral ulno-carpal space, and the consequent complex tear of the TFCC at its ulnar attachment; but what happens during the active movements? I usually perform also the dynamic evaluation, both with ultrasound and Mri exams. In this case the Cone-beam CT (CBCT) dynamic acquisitions give the answer.
about dynamic mri and ultrasound examination of carpal instability
In my previous post Dynamic Evaluation of Dorsal Scapholunate Ligament I showed the usefulness of both ultrasound and Mri dynamic evaluation in the study of this important ligament structure. Today I want to show you the dorsal scapholunate ligament (SL) tear in a patient that came to my observation after a regular healing of post-traumatic scaphoid fracture.
Coronal Stir (left) and T1w (right) Mri scans (0.3 Tesla): correct visualization with no artifacts of post-surgical treatment with scaphoid screw. Tear of the dorsal scapholunate ligament is evident (red arrow).
For the appropriate treatment is crucial to see also the dynamic behaviour of this kind of injuries. I always perform both ultrasound and Mri dynamic evaluation in these cases.
The dynamic ultrasound exam shows the post-traumatic carpal instability; dorsal SL tear is evident, togheter with the scapholunate dissociation and DISI picture.
The Dynamic Mri evaluation (0.3 Tesla) during flexion-extension and ulnar-radial deviation confirms the clinical picture, better defining all the pathologic findings. The radiology technician plays a crucial role for this kind of examination, explaining to the patient the correct wrist movement during the Mri acquisitions.
The scapholunate ligament (SL) is one of the most clinically signicant ligaments of the wrist and unfortunately, its injuries often are not diagnosed or treated during the acute phase of injury, when direct repair of the ligament would be possible. It has three components – volar, dorsal, and interosseous. The dorsal and volar represent true ligaments, whereas the interosseous component is fibrocartilage. All of the surgeons needs to know as much information as possible about the ligament anatomy and its relationships with other carpal structures, especially under dynamic conditions. In an interesting paper, Wrist MRI and Carpal Instability: What the Surgeon Needs to Know, and the Case for Dynamic Imaging the author closes the abstract with these words: “Providing specifics about the clinical questions that arise with various carpal instabilities serves to highlight the challenges facing current imaging technology, and provides a framework that supports the argument for the development of dynamic MRIas one-and perhaps the only-truly satisfactory solution to this problem“. I agree with him, definitely. In my daily practice I always perform both dynamic Mri and ultrasound examination; I find very attractive the study of carpal stability with dynamic Mri and ultrasound imaging. First knowing the normal appearance of carpal behaviour, then carpal instability.
Normal appearance of dorsal scapholunate ligament: Coronal Ge stir, 3D and X-bone T1w Mri scans (0.3 Tesla).
Axial and Sagittal T2w Mri scans (0.3 Tesla). Perfect allignement of the central osseus carpal chain is evident on sagittal scan.
Dynamic Mri of dorsal scapholunate ligament: radial and ulnar deviation.
During a standard wrist ultrasound exam, it might happen to find a bifid median nerve. According to literature it has an incidence of ~3% and may be accompanied by an accessory artery, the persistent median artery of the forearm, which lies in between the two nerve bundles.
Axial ultrasound and T2w Mri scan (0.3 Tesla)
Especially in case of carpal tunnel release it is essential that this particular anatomy be mentioned in your report in order to avoid iatrogenic injuries. Mri scan togheter with dynamic ultrasound examination and electromyography are the best choice for the evaluation of peripheral neuropathies.