Change of Carpal Alignment under Anaesthesia: Role of Physiological Axial Loading on Carpus

A. Gupta (India)

Keywords

Carpals under anaesthesia, Lunate, Axial Load, Carpal Alignment, Traction Radiograph, Radiolunate angle

Abstract

Patients with distal radial fracture undergoing general anaesthesia for management of their injury were employed for the present study. The contralateral normal wrist was assessed for any change in the carpal alignment under anaesthesia due to the eliminated physiological axial load. Lateral radiographs of the uninjured wrist joint were performed in twenty patients with distal radial fracture. Radiographs were taken before and after giving general anaesthesia along with the muscle relaxants and were repeated after applying the traction in line with the long axis of the radius. Radiographs taken under anaesthesia showed scaphoid and lunate to adapt position of relative extension with decrease in radioscaphoid, radiolunate and scapholunate angles. A further decrease in all three angles was seen in the traction radiographs. Lunate is described to have tendency to extend due to its shape which is thinner dorsally(9). Our observations however, demonstrated lunate to tend to flex in an intact carpus under the effect of the flexion torque from the scaphoid. The capitate's compressive force becomes effective and is able to extend lunate only when there is discontinuity in SLIL not allowing lunate to avail flexion torque from the scaphoid. Our results also failed to support the view that scapholunate interosseous ligament is in continuous tension due to the tendency of the scaphoid and lunate to move in the opposite directions.

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