CHAPTER 41 The Dorsal Ligaments of the Wrist
Relatively little attention or significance had been given to the dorsal ligaments of the wrist until more recent studies described the anatomical and mechanical properties of the dorsal radiocarpal ligament and the dorsal intercarpal ligament of the wrist1 and subregions of the scapholunate2–4 and lunotriquetral5 interosseous ligaments. An explanation of the functional design of the dorsal wrist ligament configuration was also offered recently.6 Dorsal approaches to the wrist have also generally ignored the ligament anatomy. Even commonly referenced and used illustrations and diagrams of the dorsal ligaments of the wrist are anatomically inaccurate.7,8
The specific anatomy of the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments of the wrist has been reported, but relatively little attention or importance has been ascribed to these ligaments in the past. The DRC has also been referred to in the literature as the dorsal radiotriquetral and the dorsal radiolunotriquetral ligament9–11 (Fig. 41-1). The distal attachments of the DRC ligament have been described by a number of authors.9–14 Some describe the ligament attaching onto the lunate,9,11,12,14 others describe it attaching onto the lunate and the scaphoid,10 whereas others report it attaching onto the lunate and capitate.13 Berger and Garcia-Elias9 described the DRC ligament attaching to the lunate and intermingling with fibers of the lunotriquetral ligament. The attachment of the DRC ligament proximally was described by all of those authors as being proximally at the dorsal aspect of the radius and its distal attachment, at least in part, including the dorsal tubercle of the triquetrum.9–14 A number of authors9–14 have reported that the DRC ligament was found to consistently have an osseous attachment proximally, at the dorsal aspect of the radius, and, distally, at the dorsal tubercle of the triquetrum. It was also found to consistently have an osseous attachment onto the distal ulnar aspect of the dorsal lunate and dorsal portion of the lunotriquetral interosseous ligament, as described by Berger and Garcia-Elias9 and Viegas and colleagues (Fig. 41-2). There were no attachments onto the scaphoid for the DRC ligament, but there was a dorsal branch or branches of the DRC ligament from the radius to the triquetrum that passed over, but did not attach to, the dorsal aspect of the proximal scaphoid, which may offer some dorsal support to the scaphoid in type II and III DRC ligaments as classified by Viegas and colleagues.6 This anatomical classification system (Fig. 41-3) was a modification of Mizuseki’s classification10 (Fig. 41-4) of the DRC ligament. Types I and IV are classified the same as his classification types 1 and 4. Mizuseki10 described that type 2, in addition to type 1, fibers have thin deltoid fibers covering the scaphoid, converging onto the triquetrum. Viegas and colleagues1 stated that these thin deltoid fibers were not detected in the dorsal structures.
FIGURE 41-2 Anatomy and the osseous/ligamentous attachments of the DRC.
(From Viegas SF, Yamaguchi S, Boyd NL, Patterson RM: The dorsal ligaments of the wrist: anatomy, mechanical properties and function. J Hand Surg [Am]. 1999; 24: 456-468, with permission.)
FIGURE 41-4 Mizuseki’s classification of the dorsal radiocarpal ligament.
(From Mizuseki T, Ikuta Y: The dorsal carpal ligament: their anatomy and function. J Hand Surg [Br]. 1989; 14:91-98, with permission.)
Function of the DRC ligament has been proposed by a number of authors.10,12,13,15 The DRC ligament has been attributed to maintaining the lunate in apposition to the distal radius.16 The direction of the fibers of the DRC ligament implies that the triquetrum is prevented from ulnar translation by the DRC ligament and the volar radiolunotriquetral ligament.10 The DRC ligament also functions as a stabilizer and pronator of the wrist. When the forearm pronates, the DRC ligament draws the attached carpus and hand passively into pronation.12,13 Some biomechanic and kinematic studies have been performed on the DRC ligament. In a 1990 anatomical and biomechanical study by Viegas and colleagues17 that was designed to better understand the pathoanatomy and pathomechanics involved in volar intercalated segment instability (VISI) deformity of the wrist, it was found that the DRC must be attenuated or disrupted for a static VISI to develop. In fact, that study demonstrated that disruption of the DRC alone would result in a nondissociative static VISI deformity. Horii and associates,18 in 1991, also confirmed the importance of the DRC in stabilizing the carpus and preventing a static VISI deformity.
A limited number of anatomical and biomechanical papers on the dorsal intercarpal ligament (Fig. 41-5) have been published. The osseous attachments of the DIC ligament have been described by a number of authors.9,10,13,19,20 Mizuseki and Ikuta described the DIC as having attachments on the dorsal tubercle of the triquetrum and trapezoid, on the capitate, and at the dorsal rough groove of the scaphoid.10 Berger and Garcia-Elias9 reported that the DIC attached to the triquetrum and the scaphoid and, to a lesser degree, on the dorsal surface of the trapezoid. Savelberg and coworkers19 found that the DIC attached to the triquetrum, the scaphoid, and the trapezium. Viegas and colleagues6 also classified the various anatomical types of DIC ligaments and found that the DIC ligament was composed of two sections. One section consisted of a more distal section of generally thinner fibers extending from the dorsal tubercle of the triquetrum to the dorsal aspect of the trapezoid or capitate. Another, more proximal thicker section extended from the dorsal tubercle of the triquetrum to the dorsal distal aspect of the lunate to the dorsal groove of the scaphoid and then to the proximal rim of the trapezium. They found that the attachment to the lunate of the DIC ligament was a consistent finding (Fig. 41-6). In 1997, Berger and Bishop described a surgical approach to the dorsal aspect of the wrist that they called a fiber-splitting or ligament-sparing approach.21 The dorsal arm of this approach follows what Berger previously described as the dorsal scaphotriquetral ligament.3 However, this would not spare the attachments of the DIC ligament, which Viegas and coworkers6 have demonstrated attach to the scaphoid, lunate, and triquetrum.
FIGURE 41-6 Anatomy and the osseous/ligamentous attachments of the DIC.
(From Viegas SF, Yamaguchi S, Boyd NL, Patterson RM: The dorsal ligaments of the wrist: anatomy, mechanical properties and function. J Hand Surg [Am]. 1999; 24: 456-468, with permission.)
Smith20 classified the DIC ligament using three-dimensional Fourier transform magnetic resonance imaging techniques. His classification is similar to that of Viegas and colleagues6 (Fig. 41-7), but the reported incidence of each type was different. Smith20 reported the incidence of three types of DIC ligaments—type 1, 14%; type 2, 44%; and type 3, 38%—which is comparable to Viegas and colleagues’1 type C, 25.6%; type A, 30.0%; and type B, 44.4%, respectively. Smith20 believed that the main portion of the DIC ligament consisted of deep fibers, whereas the superficial fibers were very thin and were not considered to be an important stabilizer of the carpus. Mizuseki and Ikuta10
