Soft Tissue Injuries of the Hand Clinical Presentation

The general history for soft tissue hand injuries includes age, hand dominance, occupation/hobbies, history of previous hand problems, other past medical history (especially diabetes, vascular problems), and smoking history.

In cases involving trauma, ascertain when and where the injury occurred to determine the likelihood of severe injury and probability of contamination with foreign matter.

How the trauma was sustained provides clues to the most likely injury. For example, a water skier who injured a hand when the towing line was removed forcefully from that hand is likely to have an injury to the flexor tendon mechanism.

Determine the posture of the hand at the time of the injury. Structures in the hand slide with movement. The tissue under a bruise or laceration may not be the same tissue that was present when the injury was sustained because of movement of structures in the hand (eg, extensor tendons injured with the digits in flexion may not be visible in the wound when digits are extended).

Past history of treatment or surgery in the hand should be noted.

The entire upper extremity should be exposed. Note any of the following findings:

• Muscle wasting

• Color change

• Surgical or nonsurgical scars

• Asymmetry

• Deformities that suggest dislocation

Look for differences in flexion/extension in the relaxed hand. The relaxed hand is in moderate flexion. The digits on both sides should be in about the same amount of flexion. The little finger usually is in more flexion than the other fingers. If a digit has a marked difference in flexion, the examiner should be suspicious for tendon injury. This finding may be useful in identifying the injury of the patient who is a poor historian.

Dry patches of skin may indicate loss of innervation.

Dimpling over the thenar eminence suggests complex dislocation of the MCP joint of the thumb.

Check range of motion in every joint in the hand, shoulder, and elbow. Ability to pronate and supinate the forearm should be tested actively and passively.

Test grip and pinch strength.

The best way to diagnose a tendon injury in an open wound is by direct visualization during a thorough exploration of the wound.

Examination of extrinsic flexors

Each of these tests is performed with and without resistance.

Flexor pollicis longus: Instruct the patient to bend the tip of the thumb against resistance.

Flexor digitorum profundus: While holding the PIP joint in extension, instruct the patient to bend the tip of the finger.

Flexor digitorum superficialis: While stabilizing the rest of the fingers to block the action of flexor digitorum profundus, instruct the patient to bend the middle joint of the finger.

Palpate the tendons of flexor carpi ulnaris, flexor carpi radialis, and palmaris longus (which is not present in about 15% of individuals) while the patient holds the wrist and fingers in hyperflexion.

Extrinsic extensors

Extrinsic extensors arise from the forearm and insert into the hand. The extrinsic extensors pass from the wrist to the hand in 6 tendon compartments, as follows:

• The first compartment contains the abductor pollicis longus and extensor pollicis brevis. Evaluate by instructing the patient to move the thumb away from the other fingers.

• The second compartment contains the extensor carpi radialis longus and extensor carpi radialis brevis. Examine by asking the patient to make a fist and extend the hand at the wrist.

• The third compartment contains the extensor pollicis longus. Ask the patient to place the hand palmar side down on a table and raise the thumb off the surface.

• The fourth compartment contains the MCP joint extensors, extensor digitorum communis, and extensor indices proprius (EIP) tendons. Evaluate by asking the patient to extend the fingers. The EIP can be evaluated alone by instructing the patient to make a fist, then extend the index finger.

• The fifth compartment contains the extensor digit minimi. Evaluate by asking the patient to make a fist and then to extend the little finger.

• The sixth compartment contains the extensor carpi ulnaris. Evaluate by instructing patient to deviate the hand in ulnar direction.

Extrinsic extensors may form adhesions secondary to old trauma. This phenomenon is referred to as extensor tightness. Extensor tightness is evaluated by passive extension of the MCP joint and flexion of the PIP joint with the wrist in anatomic position. The PIP joint should flex. Repeat the test with the MCP joint in passive flexion. If the PIP joint will flex when the MCP joint is extended but not when it is flexed, adhesions are present in the extensors, stopping the simultaneous flexion of the finger MCP and PIP joints.

Intrinsic muscles

Intrinsic muscles have their origins and insertions in the hand. They include thenar muscles, lumbricals, interosseous muscles, and hypothenar muscles.

The thenar muscles include the abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis. These muscles oppose the thumb. Test by asking the patient to place the back of the hand on the table and raise the thumb until it rests perpendicular to the hand or to touch the thumb to each finger. Palpate the muscles of the thumb and compare findings to the other side.

For the adductor pollicis, test separately by asking the patient to grasp 2 ends of a piece of cloth and hold them tightly between the thumb and index finger. Flexion of the thumb at the IP joint is called the Froment sign and indicates damage to the adductor pollicis or the ulnar nerve.

Interosseous and lumbrical muscles flex the MCP joints and extend the IP joints. The interosseous muscles are innervated by the ulnar nerve. Evaluate by asking the patient to spread the fingers and by checking the resistance to ulnar and lateral deviation of each digit in abduction. The extrinsic extensors can be used to abduct-adduct the digits if the interossei are deranged. To block their action, ask the patient to place the palm on the table and to hyperextend the digits at the MCP joints.

The hypothenar muscles include the abductor digiti minimi, flexor digiti minimi, and opponens digiti minimi. Evaluate by asking the patient to deviate the small fingers in an ulnar direction. Palpate the hypothenar eminence while the digit is in abduction.

Joint assessment

The stability of a joint is assessed by active and passive motion. Pain causes some patients to consciously or unconsciously limit the range of motion of an injured joint. Therefore, administering a digital block may be necessary prior to assessing joint stability.

Evaluate stability by applying anterior, posterior, radial, and ulnar stress to each IP and MCP joint in the extended and flexed positions. Evaluation in the flexed and extended positions is necessary, as the volar plate may stabilize a dislocated or subluxated joint in certain positions.

Sensory examination

Thoroughly inspect the skin. Denervated areas are often dry because of loss of sympathetic innervation. This may be useful in children or other patients who cannot give a history.

The immersion test also may be useful in patients who cannot give a history. Denervated skin does not wrinkle after being exposed to water for 5-10 minutes.

Two-point discrimination is the best overall test of sensory function. The distance between 2 prongs, beginning at 6 mm, is increased and decreased during the course of the exam. Abnormal discrimination values are less than 6 mm static and less than 3 mm moving. An abnormal discrimination examination implies axonal loss and sensory deficit that may be due to laceration, compression, or contusion of the nerve. If exam findings are abnormal, repeat the test on the unaffected side because the sensitivity and specificity vary from patient to patient.

Circulation

Look for color changes in the nails and skin of the hand.

The Allen test has variable sensitivity, but it may be used to help assess perfusion to the hand. Compress radial and ulnar arteries at the wrist. Instruct the patient to open and close the fist to exsanguinate the hand. Have the patient open the hand. Release the radial artery. If the hand fills with blood within 5 seconds, the radial artery is patent. Repeat the test for the ulnar artery.