Arthroscopic management of dorsal radiocarpal ligament tears

Relevant anatomy and biomechanics

The DRCL is an extracapsular ligament on the dorsum of the wrist. It originates on the Lister tubercle and moves obliquely in a distal and ulnar direction to attach to the tubercle of the triquetrum. Its radial fibers attach to the lunate and lunotriquetral interosseous ligament (LTIL). The dorsal intercarpal (DIC) ligament originates from the triquetrum and extends radially to attach to the lunate, the dorsal groove of the scaphoid, and then the trapezium. Viegas et al. have observed that the lateral V configuration of the DRCL and the DIC function as a dorsal radioscaphoid ligament. It can vary its length by changing the angle between the two arms and maintain its stabilizing effect on the scapholunate (SL) joint during wrist flexion and extension. This would require changes in length far greater than any single fixed ligament could accomplish. Elsaidi and Ruch demonstrated the importance of the DRCL on scaphoid kinematics through a series of sectioning studies. They sequentially divided the radioscaphocapitate, long radiolunate, radioscapholunate, and short radiolunate ligaments. They next divided the central and proximal scapholunate interosseous ligament (SLIL), and then the dorsal SLIL, and finally the dorsal capsule (DC) insertion on the scaphoid. There was no appreciable change in the radiographic appearance of this wrist. When the DRCL was then divided, a dorsal intercalated segmental instability (DISI) deformity occurred. In a biomechanical study using 24 cadaver arms, Short et al. determined that the SLIL is the primary stabilizer of the SL articulation and that the DRCL, the DIC, the scaphotrapezial (ST) ligaments, and the radioscaphocapitate (RSC) ligaments are secondary stabilizers. They found that dividing the DIC or the ST ligaments alone followed by 1000 cycles of wrist flexion-extension and radial-ulnar deviation had no effect on scaphoid and lunate kinematics. Dividing the DRCL alone did cause increased lunate radial deviation when the wrist was in maximum flexion. Dividing the SLIL after any of the ligaments tested produced increased scaphoid flexion and ulnar deviation while the lunate extended. They also hypothesized that cyclic motion appears to cause further deterioration in carpal kinematics due to plastic deformation in the remaining structures that stabilize the SL.

The DRCL tear described in this chapter consists of a detachment of the epiligamentous portion of the ligament. Tomita et al. have shown that more than 76% of the nerve endings were found in the two ends of the DRCL with 23.3% in the central third and approximately 80% distributed in the superficial layer. Hagert et al. have shown that the DRCL is richly innervated with Ruffini- and Pacini-like mechanoreceptors (sensory corpuscles) as well as nerve fascicles/free nerve fibers, which may be important in wrist proprioception. In cases where a dorsal capsulotomy was performed, the dorsal part of the ligament always appeared normal. I have come to believe that the pain secondary to a DRCL tear represents an impingement phenomenon of the torn DRCL that is caught between the radius and lunate during wrist motion, and that an arthroscopic repair does not necessarily restore normal wrist kinematics—but there is no biomechanical data to support either theory.

Diagnosis

An isolated DRCL tear is a diagnosis of exclusion. The typical patient presents with a history of intermittent dorsal wrist pain, without any obvious inciting event. A history of recurrent 1- to 2-day flare-ups of pain followed by an asymptomatic period of weeks or months is common. There is usually no clear history of injury or a fall. The physical examination reflects the findings that are present with any associated pathology, such as a positive Watson test with a SL instability, or foveal tenderness with a triangular fibrocartilage complex (TFCC) tear. A patient with an isolated DRCL tear typically has no localizing physical findings, and often presents with an entirely normal examination. None of the wrists in my series showed a static carpal instability pattern on radiographs. None of the DRCL tears were identified with preoperative arthrography or MRI. A preoperative MRI in one patient with a DRCL tear, however, was misinterpreted as representing a dorsal wrist ganglion ( Fig. 8.1 A–B). The diagnosis was always established at the time of wrist arthroscopy by direct visualization of the tear through the volar radial (VR) portal.