MRI of the Wrist

Marcos Loreto Sampaio, MD; Nicholas M. Kolanko, MD

Disclosures

Appl Radiol. 2014;43(10) 

In This Article

Ligaments

The scapholunate ligament (SLL) is the most relevant intrinsic ligament of the wrist that can be assessed with MRI. The SLL comprises 3 bands, of which the dorsal is mechanically the most important, followed by the volar and central bands. The volar band, protected by a strong adjacent extrinsic ligament, is less prone to injury. The third and less relevant central band, a membranous portion, is frequently perforated in adult individuals without clear consequence for wrist biomechanics. For this reason, communication between the radiocarpal and midcarpal compartments during fluoroscopic or MR arthrograms does not necessarily represent a symptomatic finding or reflect a traumatic tear of the ligament. As a result, the different bands should be assessed separately with MRI.

The dorsal band is easily seen on axial-plane and coronal-plane images, where it often presents some degree of partial-volume artifact. In normal cases, it is a continuous, thin, low-signal-intensity band bridging the chondral margins of the lunate and scaphoid. The insertion in the hyaline cartilage should not be mistaken for a tear. Signal changes and altered thickness may represent degeneration or even previous partial injuries, and are sometimes associated with a ganglion. The accuracy of these findings is, however, controversial.[15] Disruption or indistinction of the fibers indicates a full-thickness tear of the component. Tears of the dorsal component or complete tears (disruption of all 3 components) are also more frequently symptomatic and secondary to trauma (Figure 7).[16] Widening of the scapholunate interval may be seen, but this finding implies an associated injury of the extrinsic ligaments.[17] A similar rationale is applied to the volar component, except that it may demonstrate intermediate signal intensity in normal cases.[18]

Figure 7.

Complete tear of the scapholunate ligament. Axial PD-weighted image with fat suppression. High signal intensity and indistinction of the fibers of both dorsal (arrow) and volar (dashed arrow) components. The membranous portion was also torn.

The lunotriquetral ligament (LTL) is also composed of three components, but the volar band is the most relevant for stability. The whole extension of the ligament and its tears may be difficult to detect; the presence of a step-off between the lunate and triquetrum, central tears of the triangular fibrocartilage, and findings compatible with ulnocarpal abutment warrant careful LTL examination.[19]

The multiple dorsal and volar extrinsic ligaments are low-signal bands overlying the carpal bones and intrinsic ligaments.[20] Signal changes along their topography in cases of posttraumatic injury may indicate sprain.[19] Often, a ganglion cyst may also be seen traversing ligamentous fibers toward the superficial soft tissues.

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