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Ulnar wrist pain revisited: ultrasound diagnosis and guided injection for triangular fibrocartilage complex injuries
Ulnar wrist pain revisited: ultrasound diagnosis and guided injection for triangular fibrocartilage complex injuries
REVIEWED BY Sean Yeoh | ASA SIG: Musculoskeletal
REFERENCE | Authors: Wu W, Chang K, Mezian K, Nanka O, Yang Y, Hsu Y, Hsu P & Özçakar L
WHY THE STUDY WAS PERFORMED
Triangular fibrocartilage complex (TFCC) injuries are the most common cause of ulnar wrist pain. Diagnosing TFCC injuries is traditionally reliant on magnetic resonance imaging (MRI). Recently, studies have emerged showing the potential of ultrasound (US) in diagnosing TFCC lesions, but the adaptation has been limited as the US anatomy and pathology of the TFCC are poorly described in the literature, in addition to not having a standardised scanning protocol.
Wu et al. aimed to propose a standardised scanning protocol for the TFCC with respect to:
anatomy
pathology
US-guided injections.
WHAT THE REVIEW DESCRIBED
The review paper described the cadaveric and sonographic anatomy, mechanism of injury and physical examinations, MRI and US imaging appearance, scanning protocol, pathologies and treatments of the TFCC.
TFCC injuries can affect the articular disc, meniscus homologue, juxta-articular ligaments and the extensor carpi ulnaris tendon (ECU) sub-sheath. Wu et al. proposed US evaluation of the TFCC by a seven-image series (five on the dorsal aspect, three in transverse and two in longitudinal, two on the volar aspect, and one in both transverse and longitudinal), which allowed demonstration of all components. They also proposed a modified Palmer classification system for the ultrasound appearances of injuries. Class 1 (traumatic) and class 2 (degenerative), each having five subgroups a–e, which correspond to the location and/or degree of injury.
The articular disc is the major component of the TFCC and appears hypoechoic on ultrasound. In transverse (Figure 1), it appears as a hypoechoic disc-shaped structure and in longitudinal, the disc can be seen thinning towards its radial aspect. Between the styloid process and the articular disc lie (from superficial to deep) the ulnar collateral ligament, meniscus homologue and the two limbs (superficial and deep) of the radioulnar ligament. The layering and relationship between the various components, styloid process, ulnar fovea and ECU, serve as important reproducible sonographic landmarks in both longitudinal and transverse imaging.
Pathology of the TFCC has a broad sonographic appearance. Acute defects of the articular disc appear as hypoechoic clefts/defects. The meniscus homologue, by comparison, is generally heterogenous with injuries typically appearing as inhomogeneous central echoes. Degenerative changes vary from thinning of the articular disc and cortical irregularities to partial to complete tears of the juxta-articular ligaments.
Ultrasound shows promise as a viable imaging modality of the TFCC providing a systematic approach is used in conjunction with a broad understanding of the TFCC components and sonographic appearance of pathologies.
RELEVANCE TO CLINICAL PRACTICE
Ultrasound shows promise as a viable imaging modality of the TFCC providing a systematic approach is used in conjunction with a broad understanding of the TFCC components and sonographic appearance of pathologies. Acceptance of ultrasound for imaging the TFCC would allow clinicians to provide accurate treatment plans sooner, as access to MRI can be limited. Future studies comparing the sensitivity of MRI versus US will be crucial for ultrasound to become a viable first point of call for TFCC imaging. This paper highlights suggestions for the sono-anatomy, and due to the lack of consensus in many studies regarding the subcomponents of the TFCC and their relationships, further studies to clarify the sono-anatomy of the subcomponents of the TFCC are required.
