Effect of wrist position on distal radioulnar joint stability: A biomechanical study

Abstract

We investigated distal radioulnar joint (DRUJ) stability in different wrist positions and examined the relative contribution of each ligamentous component of the triangular fibrocartilage complex (TFCC) to DRUJ stability. We used nine fresh-frozen cadavers. The humerus and ulna were fixed at 90˚elbow flexion. The radiocarpal unit was translated relative to the ulna in dorsopalmar directions with the wrist in five positions. Displacement of the unit was measured by an electromagnetic tracking device. Magnitudes of displacement were compared between different wrist positions in various sectioning stages: ulnocarpal ligament (UCL) sectioning, radioulnar ligaments (RUL) sectioning, and extensor carpi ulnaris (ECU) floor sectioning. Wrist position and sectioning stage significantly influenced the displacement. In intact wrists, the displacement in wrist extension was significantly lower than that in neutral. However, after UCL sectioning, there were no longer any significant differences. After RUL sectioning, the displacement in radial deviation was significantly lower than that in neutral. Following ECU floor sectioning, there were no longer any significant differences. Thus, in intact wrists, DRUJ stability in wrist extension is likely due to tightening of the UCL. After complete RUL sectioning, DRUJ is stabilized in radial deviation due to tightening of the ECU floor. the DRUJ capsule, 6 and musculotendinous structures. 7,8 The dominant stabilizing structures are the ligamentous components of the triangular fibrocartilage complex (TFCC), and the primary stabilizers are the dorsal and volar radioulnar ligament (RUL). 4 The other ligamentous components of the TFCC are the ulnocarpal ligament (UCL) and the floor of the extensor carpi ulnaris (ECU).2,9 The ulnar collateral ligament consists of a component of the floor of the ECU. 10The UCL arises from the ulnar fovea and palmar RUL and inserts distally into the palmar aspects of the lunate, capitate, and triquetrum.11 The UCL supports the ulnar carpus from the palmer aspect, stabilizing the ulnocarpal joint. Several biomechanical studies revealed that the UCL does not contribute significantly to DRUJ stability in wrist neutral position. 4,5,13 Although, the UCL itself does not stabilize the DRUJ, the UCL might contribute to stability of the DRUJ in specific wrist positions.11,12 Moritomo et al.14 investigated the lengths of the UCL in wrist radial deviation and extension with 3D in vivo analysis using computed tomography. They found that the UCL elongates and is likely stretched more in these positions. Therefore, we speculated that the UCL stabilizes the DRUJ in wrist radial deviation and extension. Moreover, the ECU floor includes fibers of ulnar collateral ligament, contributing ulnar collateral stability of the ulnocarpal joint. Therefore, we also speculated that when the wrist is radially deviated, increasing tension of the floor stabilizes the DRUJ by radial shift of the distal ulna.To our knowledge, only a single previous clinical study investigated D...

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Effect of decrease in radial inclination of distal radius fractures on distal radioulnar joint stability: a biomechanical study

“…Radial deviation of the carpus decreases DRUJ shear, implying increased stiffness (Iida et al, 2014;Pickering et al, 2016). As the wrist may have tendency to a radial deviated position with the radial angulation deformity, the radial deviation may contribute to an increase in DRUJ stiffness.…”

A Biomechanical Perspective on Distal Radioulnar Joint Instability

“…2. Wrist extension and radial deviation: Our previous biomechanical study revealed that wrist position significantly influenced DRUJ laxity, 25 DRUJ was more stable in wrist extension than neutral position before the UCL sectioning. After the UCL sectioning, there were no longer any significant differences in laxity.…”

“…We investigated DRUJ stability in different wrist positions and examined the relative contribution of each ligamentous component of the TFCC to joint stability with applying 40 N of force of dorsopalmar translation of the ulna with respect to the radius. 25 The magnitudes of displacement while in a neutral wrist position were compared with the intact wrists (7 mm of translation) and those at various stages of sequential ligament sectioning: UCL sectioned, RUL sectioned, and ECU floor sectioned (►Table 2). UCL sectioning only had no significant influence on joint stability in a neutral position (7 mm).…”