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The hand is innervated by the median, ulnar, and radial nerves. Motor function of the median nerve can be screened by flexing the thumb distal phalanx against resistance, the ulnar nerve by spreading the fingers against resistance, and the radial nerve by maintaining extension of the finger MCP joints against resistance. Sensory innervation (Fig. 170-1) is best screened by the presence of normal two-point discrimination (<5 mm). Injuries requiring hand surgery consultation are listed in Tables 170-1 and 170-2.

Figure 170-1

The cutaneous nerve supply in the hand. DCU, dorsal cutaneous branch of ulnar nerve; M, median nerve; PCM, palmar cutaneous branch of median nerve; R, superficial radial nerve; U, ulnar nerve.

Table 170-1

Immediate Hand Surgery Consultation Guidelines

Table 170-2

Delayed Hand Surgery Consultation Guidelines

Tendon injuries can be easily missed. Up to 90% of a tendon can be lacerated with preserved range of motion without resistance, so test function against resistance and compare to the uninjured side. Pain along the course of the tendon suggests a partial laceration even if strength is normal. Although extensor tendon repair has often been performed by the emergency physician, there is a movement toward operative repair. Flexor tendon repair should be performed by the hand surgeon. It is acceptable to stabilize the injury by closing the skin and splinting until definitive repair by the hand surgeon. Follow-up and rehabilitation of all tendon injuries are necessary, even those not requiring repair.

Mallet finger results when complete rupture of the extensor tendon occurs at the level of the distal phalanx. On examination, the distal interphalangeal (DIP) joint is flexed at 40°. Splint the DIP joint in slight hyperextension.

Boutonniere deformity results from an injury at the dorsal surface of the proximal interphalangeal (PIP) joint that disrupts the extensor hood apparatus. Lateral bands of the extensor mechanism become flexors of the PIP joint and hyperextensors of the DIP joint. Splint the PIP joint in extension.

DIP joint dislocations are uncommon because of the firm attachment of skin and fibrous tissue to underlying bone. Dislocations are usually dorsal. Reduction is performed under digital block anesthesia. The dislocated phalanx is distracted using longitudinal traction, slightly hyperextended, then repositioned. Splint the joint in full extension. An ...

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