Normal Anatomy of the Extrinsic Capsular Wrist Ligaments by 3-T MRI and High-Resolution Ultrasonography

Abstract

The anatomy of the extrinsic capsular wrist ligaments is complex. These ligaments are probably as important as the intrinsic interosseous ligaments for the maintenance of carpal stability. The extrinsic capsular wrist ligaments are frequently divided into dorsal, palmar, and collateral depending on their anatomical location. They have known origin and attachment sites with recognized anatomical variants. However, there is controversy in the literature related to their anatomy and nomenclature. In the past two decades, imaging has gained an important role in the evaluation of the extrinsic capsular wrist ligaments. Both 1.5-T magnetic resonance imaging (MRI) and magnetic resonance arthrography can provide good evaluation of the extrinsic capsular wrist ligaments; 3-T MRI with improved resolution provides better visualization of the same anatomical structures. Ultrasonography using high-resolution linear transducers allows good visualization of the extrinsic capsular wrist ligaments with results that are comparable with MRI. This article describes the normal anatomy of the dorsal, palmar, and collateral extrinsic capsular wrist ligaments on 3-T MRI and high-resolution ultrasonography.

MR Imaging of Wrist Ligaments

“…43,101,102 Both intrinsic ligaments, referred to as primary stabilizers, and extrinsic ligaments, referred to as secondary stabilizers, are important for maintaining carpal stability. 6,18,103,104 Isolated intrinsic ligament tears are not associated with carpal instability. 6 As in other parts of the body, imaging evidence of disorder must be carefully correlated with the patient's symptoms; in a recent study, an average of 3.15 abnormalities, including ligament tears, per asymptomatic wrist were identified on MR imaging.…”

“…Both form a V, flanking the proximal normal zone of volar capsular deficiency, in the carpal tunnel floor, known as the space of Poirier, through which volar lunate dislocation occurs. 18,43,44,57 Although technically separate structures, particularly proximally, the arcuate and deltoid ligaments blend imperceptibly with each other as they approach their common attachment on the capitate, making them practically indistinguishable distally. 20 In the literature, the arcuate ligament is sometimes referred to as the deltoid ligament 44 and the deltoid ligament referred to as the arcuate ligament.…”

“…9). 18,34,39 Both ligaments take a distal and ulnar oblique course, traversing a groove in the scaphoid waist, most easily shown in the sagittal plane. 17,25 As previously noted, the RSL attaches to the palmar aspect of the distal scaphoid pole and the central palmar capitate, whereas the LRL inserts widely on the palmar lunate (Fig.…”

Magnetic Resonance Arthrography of the Wrist and Elbow

“…13,22,23 These ligaments generally demonstrate homogeneously low signal intensity on MR imaging. 13,22,23 Volar extrinsic ligaments include the radioscaphocapitate ligament (RSCL), radiolunotriquetral ligament (RLTL, also known as the long radiolunate ligament), and the short radiolunate ligament. The RSCL is the most important volar extrinsic ligament, and the RSCL and RLTL can contain normal bands of higher signal on MR imaging/MR arthrography.…”

“…The RSCL is the most important volar extrinsic ligament, and the RSCL and RLTL can contain normal bands of higher signal on MR imaging/MR arthrography. 13,22,23 The radial collateral ligament (RCL) of the wrist arises as a focal condensation of the joint capsule, just deep to the extensor tendon sheath; it originates from the radial styloid and inserts onto the scaphoid waist. 13,22 Carpal instability may occur when there is concomitant injury to the intrinsic and extrinsic interosseous ligaments.…”