The Journal of hand surgery
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The anatomy of the palmar aponeurosis pulley has been well described, but its biomechanical function is not as well characterized. This study describes the functional importance of the palmar aponeurosis pulley by using efficiency parameters. We obtained data by generating load, excursion, and work efficiencies in the intact pulley system and compared these to the efficiencies obtained after sectioning the palmar aponeurosis pulley alone and in combination with the proximal annular pulleys. ⋯ Change in work is due not only to an increase in excursion, but also to the increased resistance that results from the acute angulation that the tendon must endure as it follows behind the remaining pulleys during flexion. Intergroup comparisons show a significant contribution by the palmar aponeurosis pulley. This study demonstrates a significant biomechanical role for the palmar aponeurosis pulleys and suggests that it be considered similar to the annular and cruciate flexor tendon pulleys in importance.
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A biomechanical cadaver study was performed to determine the roles of the stabilizing structures of the distal radioulnar joint during pronation and supination. Subluxation and dislocation of the radius with respect to the ulna were evaluated in seven cadaver forearms placed in supination, pronation, and neutral forearm rotation. The amount of subluxation was measured with all structures intact, and after sectioning in various sequences the dorsal and palmar radioulnar ligaments, the distal portion of the interosseous membrane including the pronator quadratus, and the entire interosseous membrane. ⋯ When the interosseous membrane was disrupted first, the dorsal radioulnar ligament was found to be more important than the palmar radioulnar ligament in stabilizing the distal radioulnar joint in pronation, and conversely the palmar radioulnar ligament was more important than the dorsal radioulnar ligament in supination. Dislocation, and frequently diastasis, occurred only with sectioning of all four structures. This suggests that all four structures contribute to stability of the distal radioulnar joint.