++
The physical examination of the hand begins with observation. Look for lacerations, puncture wounds, soft-tissue swelling, deformity, and color. The resting hand should demonstrate increasing flexion from the index through little finger and increasing flexion of the joints, from the distal interphalangeal (DIP) through metacarpophalangeal (MCP) joints. Disruption of this normal cascade implies a laceration to an extensor or flexor tendon. A complete flexor tendon laceration results in straightening of the finger due to the unopposed extensors. A complete extensor tendon laceration results in flexion of the finger due to the unopposed flexors.
++
Malrotation as a result of a phalangeal or metacarpal fracture will occur occasionally. Alignment may appear normal in extension but be grossly abnormal with the fingers flexed. Malrotation may lead to significant cosmetic and functional impairment, so the diagnosis should be made on initial presentation to avoid permanent disability. A useful method to test for malrotation is to have the patient alternately flex the fingers to the palm. Each finger converges to the same place on the palm, the tubercle of the scaphoid. Patients with significant malrotation will violate this pattern with the affected finger. Another method is to compare the planes of the fingernails with the fingers in flexion. The nail plates should be approximately parallel and symmetric to the opposite hand. Any abnormal tilting is evidence of a rotational deformity.
++
Gently palpate the injured hand. The examination should be performed with the patient's hand resting comfortably on a flat surface. One may use a fingertip or an object such as the eraser end of a pencil or the end of a cotton-tipped applicator to find the exact area of maximal tenderness. Maximal tenderness over the radial or ulnar aspect of an interphalangeal joint indicates a collateral ligament tear. Tenderness over the volar aspect of an interphalangeal joint indicates volar plate injury. Tenderness over the ulnar aspect of the thumb MCP joint indicates a gamekeeper's thumb (torn ulnar collateral ligament of the thumb). Pain elicited with palpation over the anatomic snuff-box is presumptive evidence for a scaphoid fracture.
++
Circulation is best assessed by observing color, testing for capillary refill, and determining skin temperature. A cyanotic, edematous hand indicates venous insufficiency. A pale cool hand or a finger with poor capillary filling indicates arterial insufficiency. Doppler ultrasound or an Allen test may determine adequacy or circulation. Brisk arterial bleeding can be managed by pressure. Blindly clamping arterial bleeders may cause further harm by damaging nerves, arteries, tendons, and muscle. Arterial bleeding from a volar laceration implies laceration of the digital nerve since these nerves are located superficial to the artery.
++
Sensation in the cooperative patient is best tested by two-point discrimination. Each digital nerve is tested. This may be performed with a bent paper clip gently touching the tip of the finger along the longitudinal axis. Normal two-point discrimination is 3 to 5 mm. In children too young or too afraid to cooperate, two other methods of sensory testing have been reported: loss of skin wrinkling and loss of sweating. After the hand is soaked in warm water for 30 minutes, the skin wrinkling is lost after digital nerve injury. Skin sweating is responsible for the “tackiness” of the fingertips and relies on intact sympathetic innervation. Following digital nerve injury, the ability to sweat is lost, and the skin takes on a smooth, silky texture. This may be tested by moving a smooth object, such as the barrel of a pen, over the fingertip. In the injured finger, the barrel will move smoothly; in the normal finger, there will be resistance. As always, a high index of suspicion is required for successful diagnosis.
++
The ulnar nerve is tested by having the patient abduct the index finger against resistance while palpating the first dorsal interosseous muscle. The median nerve is tested by having the patient palmar abduct the thumb against resistance while the examiner palpates the belly of the abductor pollicis brevis muscle, located on the radial aspect of the thenar eminence. The radial nerve is tested by having the patient extend the fingers and wrist against resistance. The anterior interosseous nerve (a branch of the median nerve) is evaluated by flexion of the distal phalanx of the index finger.
++
Examination of the hand for tendon injury is particularly difficult in small children. The child's pain, anxiety, and unwillingness to cooperate, as well as partial tendon lacerations, can thwart the unwary examiner. The flexor digitorum profundus is tested by immobilizing the PIP and MCP joints and allowing the patient to flex the DIP joint against resistance. The flexor pollicis longus is tested by immobilizing the MCP joint of the thumb and allowing the patient to flex the interphalangeal (IP) joint. The flexor digitorum superficialis is tested by immobilizing the MCP joint and allowing the patient to flex the PIP joint against resistance. This test does not work for the index finger since the flexor digitorum profundus cannot be immobilized. To test the index finger, have the patient hyperextend the DIP joint with force against the thumb (thumb index pinch). If the patient is able to do this, the superficialis is intact. Patients with a superficialis laceration will not be able to hyperextend the DIP joint but will accomplish pinch by flexion of the DIP joint. The flexor carpi radialis is tested by flexion and radial deviation of the wrist against resistance. The flexor carpi ulnaris is tested by flexion and ulnar deviation of the wrist against resistance.
++
Since evaluating young patients is difficult, depending on age and willingness to cooperate, other tests may be required to determine tendon function. With the elbow resting on the table, allow the wrist to naturally fall into flexion. It is noted that the fingers fall into extension. When the wrist is relaxed in extension, the fingers fall into the normal cascade of flexion. This normal flexion and extension of the fingers relies on an intact tendon system. Another method to assess the flexor tendons is palpation of the forearm to create passive motion of the fingers. This is performed by pressing or squeezing the forearm at the junction of the middle and distal thirds on the ulnar–volar surface. This will cause flexion of the fingers, especially the three ulnar fingers. A similar test can be performed for the flexor pollicis longus by pressing on the distal forearm on the midvolar aspect. An intact flexor pollicis longus will result in flexion of the interphalangeal joint of the thumb. The flexor tendons and associated functions are listed in Table 30-4. The extensor tendons are tested as described in Table 30-5. Note that the extensor tendons are divided into six different compartments.
++
++
++
Obtain oblique views of the fingers along with the standard AP and lateral views of the hand. The epiphyses of the phalanxes and first metacarpal are located proximally. The epiphyses of the rest of the metacarpals are distal. Accessory bones should not be confused as fractures. In the lateral view, each finger should have more flexion than the next to avoid overlapping of finger images. A scaphoid or navicular view elongates the profile of the scaphoid and may improve fracture identification.