Quantitative Assessment of Distal Radioulnar Joint Stability With Pressure-Monitor Ultrasonography

Patients and healthy volunteers will be tested sitting with the elbow flexed and the forearm pronated. The forearm of the examinee will be secured to the table. The hand will be positioned on an adjustable block such that the forearm will be in a horizontal position. At the distal radioulnar joint level, the transducer will be maintained perpendicular to the longitudinal axis of the ulna. The dorsal surface of the distal radius and the center of the ulnar head will be displayed on a monitor.To determine the same measurement level in each volunteer, the highest aspect of the ulnar head will be taken. The DRUJ motion during cyclic loading toward the palmar direction at the distal ulna will be recorded. The compression-release cycles will be applied with the pressure-monitor ultrasound system. The cycle will be set to 1.5Hz. The pressure in the palmar direction will be applied with different levels of transducer displacements, i.e. 1 mm, 2 mm, and 3 mm.