Role of Ligament Stabilizers of the Proximal Carpal Row in Preventing Dorsal Intercalated Segment Instability

Abstract

Background: Isolated injuries of the scapholunate interosseous ligament (SLIL) are insufficient to produce dorsal intercalated segment instability. There is no consensus about which additional ligamentous stabilizers are critical determinants of dorsal intercalated segment instability. The aim of this study was to evaluate the role of the long radiolunate (LRL), scaphotrapeziotrapezoid (STT), and dorsal intercarpal (DIC) ligaments in preventing dorsal intercalated segment instability. Methods: Thirty fresh-frozen forearms were randomized to 5 ligament section sequences to study the SLIL, LRL, STT, and DIC ligaments. The DIC-lunate insertion (DICL) and scaphoid insertion (DICS) were studied separately; the DIC insertions on the trapezium and triquetrum were left intact. Loaded posteroanterior and lateral fluoroscopic images were obtained at baseline and repeated after each ligament was sectioned. After each sequence, the wrists were loaded cyclically (71 N). The radiolunate angle was measured with load. Dorsal intercalated segment instability was defined as an increase of >15° in the radiolunate angle compared with baseline. Results: Division of the SLIL did not increase the radiolunate angle. Section of the SLIL+LRL or SLIL+DICL significantly increased the radiolunate angle but did not produce dorsal intercalated segment instability. Section of the SLIL+STT or SLIL+DICL+DICS produced dorsal intercalated segment instability. Conclusions: In order to produce dorsal intercalated segment instability, complete scapholunate injuries require the disruption of at least 1 critical ligament stabilizer of the scaphoid or lunate (the STT or DICL+DICS). Clinical Relevance: When treating SLIL tears with dorsal intercalated segment instability, techniques to evaluate the volar and dorsal critical stabilizers of the proximal carpal row should be considered.

Four-Dimensional CT Analysis of Dorsal Intercalated Segment Instability in patients with Suspected Scapholunate Instability

“…Pérez et al, in a cadaveric study, evaluated the role of the scaphotrapeziotrapezoid, and dorsal intercarpal (DIC) ligaments in preventing DISI. 18 To produce that deformity, SLL injuries require the associated disruption of at least one extrinsic ligament, stabilizer of the scaphoid or lunate. Mitsuyasu et al had already highlighted the essential role of the DIC in stabilizing the scaphoid and lunate and preventing DISI deformity in cases of SLI.…”

Postoperative Pain Is Correlated with Scaphoid Dorsal Translation following Scapholunate Interosseous Ligament Reconstruction

“…DST is related to the dorsal scaphoid translation that occurs in Watson's "scaphoid shift test" 21 and to the dynamic scaphoid subluxation that occurs with wrist flexion in patients with SL dissociation. 22,23 We believe that static or dynamic dorsal scaphoid translation causes abnormal shear stress across the cartilaginous scaphoid proximal pole, with resultant painful cartilage degradation and eventual arthritic change. Various cadaveric 24,25 and clinical 26,27 studies have shown that patients with complete SLIL injuries exhibit abnormal kinematics of the carpal bones including dorsal and radial translation of the scaphoid, flexion and pronation of the scaphoid, extension and supination of the lunate, and also dorsal translation of the capitate, trapezoid, and trapezium.…”

The application of computer-based quantitative analysis to explain carpal biomechanics

“…The specific defects can be characterized by a variable loss of the scaphoid trapezium ligaments, the LRL, the dorsal scapholunate connection and the connection of the lunate to the DIC. Recent studies have provided additional support for the important role of the LRL and dorsal ligamentous connections (Pérez et al., 2019). A detailed explanation is beyond the summary in this article and is covered by other publications (Sandow, 2020b; Sandow and Fisher, 2020).…”