REIDER PART 1
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116 Chapter 4 Hanc! and Wrist

Figurę 4-21. A, Prominence of flexor carpi radialis (solid arrow) and palmaris longus (open arrow) increascd by active wrist flexion. B, Dcmonstration of palmaris longus tendon by pinching (arrow).

Alignment

Alignment may be first assessed with the fingers and the thumb fully extended and the wrist in a neutral position. Whether viewed from their dorsal or volar aspects, the fingers and the thumb should appear straight and in alignment with their respective metacarpals (Fig. 4-25A).

Figurę 4-22. Yolar wrist ganglion.

Acute or malunited fractures of the phalanges are the most common cause of angular deviations from normal straight alignment. Ulnar deviation of the MCP joints of the fingers is a common deformity in rheumatoid arthri-tis (Fig. 4-26). In this case, the rheumatoid synovitis dis-rupts the extensor hoods over the heads of the digital metacarpals, allowing the extensor tendons to slidc to the ulnar aspect of each metacarpal and thus puli the fingers into flexion and ulnar deviation.

Finger Deformities. Sagittal alignment may be assessed by inspecting the fingers and thumb from either side while the patient holds the digits in fuli cxtension. When fully extended, the normal fingers and thumb should hyperextend slightly, exhibiting a smooth, gentle curve (see Fig. 4-27/2). A number of common deformities are visible from this pcrspective. Avulsion of the insertion of the extensor digitorum communis from the dorsal base of the distal phalanx of one of the fingers is called a mallet finger. When a mallet finger deformity is present, the DIP joint of the involved finger remains in slight flexion when the patient attempts to extend all fingers (Fig. 4-27A).