REIDER PART 1
18

108 Charter 4_Hand and Wrist

Figurę 4-11. Active extension to demonstrate extensor pollicis longus tendon (arrow).

rangę from just barely palpable to golf ball-sized. They most commonly appear immediately adjacent to the radial wrist extensors, but they may dissect morę proxi-mally and distally as they enlarge (see Fig. 4—12D). Ganglia become morę prominent with wrist flexion. The transillumination test can confirm the diagnosis of a gan-glion cyst, as the ganglion glows when a pen light is shown through it (see the Manipulation section).

Radial (Lateral) Aspect

Thumb. Rotating the patient’s forearm into the neutral, thumb up, position allows the examiner to study the radial aspect of the hand and wrist directly (Fig. 4-13). This position allows a morę direct vicw of the dorsum of the thumb. As with the fingers, the examiner looks for abnormalities about the thumb, first at the fingernail or areas for swelling or ecchymosis that might signify a frac-ture or joint injury. The metacarpophalangeal joint of the thumb, the first metacarpophalangeal joint, is normally quite prominent and easily visualized. Injuries to the ulnar collateral ligament of the first metacarpophalangeal joint, often called skier’$ thumb or gamekeeper^ys thumb, arc a common cause of swelling at that location.

Although the thumb has only two phalanges, its metacarpal is much morę mobile than the metacarpals of the other fingers and thus assumes sonie of the functions of a third phalanx. The proximal end or base of the first metacarpal, which serves as the insertion site of the abductor pollicis longus tendon, produces a visible step-off in the contour of the hand. Abnormal enlargement of this prominence is a common sign of arthritis of the basi-lar joint (Fig. 4-14) between the base of the first metacarpal and the trapezium.

Figurę 4-12. A, Wrist swelling in rhcumatoid arthritis [arrow). B, Swelling from nondisplaced fracture of the distal radius [arrows). C, $ilver fork deformity. D, Dorsal wrist ganglion [arrow).