Soft Tissue Injuries of the Hand Treatment & Management

The prevalence and acute nature of soft tissue injuries to the hand require that the emergency physician understand the principles of evaluation and treatment. Mutilation of the hand may be taken to include injuries that result in significant damage to several tissues at once. The patterns of these injuries are highly variable because of the numerous permutations and combinations of the severity, extent, and the number of tissues involved that the treatment. ^[15]  The final functional outcome of each injury is unique and varies with the severity of structural damage and contamination, as well as surgery and rehabilitative care. The overall goal of reconstruction is restoration of maximal function in the shortest possible time with the minimum number of procedures. ^[15]

Time considerations

The time that a patient was injured and the time of presentation to the ED should be recorded. Certain types of injuries require rapid response to prevent unfavorable outcomes. The following injuries require immediate treatment after diagnosis:

• Vascular injuries that cause hemorrhage

• Vascular injuries that compromise perfusion

• Compartment syndromes

• Amputations with potential for reimplantation

• Hydrofluoric acid burns

• High-pressure injuries

• Self-inflicted injuries: Multiple lacerations that are partial thickness and parallel to each other are known as hesitation marks. Hesitation marks are indicative of self-inflicted injury. Psychiatric consultation is recommended for any intentionally self-inflicted wound.

Lacerations

Skin wounds of the hand, although commonplace, should not be trivialized. They must be handled with a methodical and thorough approach to optimize outcome and minimize morbidity.

After the initial examination and a decision regarding need for radiologic studies, anesthetize the hand wound with buffered lidocaine. A digital block is preferable for digital injuries but only after a careful sensory exam, including 2-point discrimination.

Next, irrigate the wound profusely using clean or sterile water under pressure. Care should be taken not to infiltrate the wound with the irrigant.

Drape the wound and examine it carefully under proper lighting, including visualization of the entire wound during a full range of motion. Search vigorously for foreign bodies or evidence of tendon injuries.

To achieve hemostasis during wound exploration, fasten a sterile Penrose drain to the base of a digit. Do not use a rubber band, which can easily be overlooked and lead to an ischemic digit. Inflate a blood pressure cuff to over 200 mm Hg, then clamp the tube to achieve good hemostasis. Total tourniquet time in the ED should not exceed 2 hours.

Close the skin wound with a single layer of simple or horizontal mattress sutures. ^[7] Deep sutures should seldom, if ever, be placed in the ED because of the risk of infection and granuloma formation.

Hand wounds older than 6-8 hours should not be closed primarily, because of an increased likelihood of infections. Irrigate and explore such wounds and apply a sterile dressing. Recheck the wound in 2-4 days, with consideration of delayed primary closure at 4 days.

Similarly, most bite wounds and wounds sustained by blunt injury to another person's mouth (a "fight-bite") should not be closed primarily but should be given serial wound checks with delayed closure at 4 days if needed.

Antibiotic prophylaxis is indicated in human (including fight-bites) and cat bites and may be of benefit in dog bites as well. The use of antibiotics in other hand wounds is controversial but generally is best reserved for contaminated wounds and puncture wounds with possible retained foreign bodies.

Nerve injury

A completely disrupted nerve should be repaired microsurgically. However, in the acute setting, distinguishing the severity of nerve damage often is impossible. Consultation with a hand surgeon is advised.

Primary repair is optimal, but if delayed repair is advised because of a dirty wound, multiple injuries, or logistic constraints, the finger/hand involved should be splinted and the patient should receive prompt follow-up with a hand surgeon.

Sprains

Patients with an unstable joint need referral to a hand surgeon for nonurgent follow-up.

The collateral ligaments of the MCP joints are tensed when the joints are flexed and relaxed in extension, just the opposite of most other collateral ligaments. Prolonged immobilization in extension may shorten these ligaments and result in reduced mobility of the joints. Therefore, MCP joints usually are immobilized in 50-60° of flexion. PIP joints should be splinted in 20-30° of flexion.

Injuries to the collateral ligaments are treated according to the degree of injury:

• Dynamic splinting, also known as buddy taping, may be used for first-degree sprains.

• A second-degree sprain should be placed in an aluminum splint.

• Third-degree injuries, involving the collateral ligaments and volar plate, require an aluminum splint or a plaster gutter splint and referral to a hand surgeon.

• Volar plate injuries should be immobilized in a plaster or aluminum splint and the patient referred to a hand surgeon.

Dislocations

For distal interphalangeal joints, radiographic studies are indicated to rule out fractures. Reduce the dislocation after administering a digital or metacarpal block. While holding the phalanx proximal to the injury, apply a distracting force along the longitudinal axis of the digit. While maintaining traction, hyperextend the phalanx (for dorsal dislocations) and bring it back to its normal anatomic position. Examine the joint thoroughly after reduction. Then immobilize the finger with an aluminum splint. If the joint is irreducible, consultation with a hand surgeon is required. Inability to reduce a digit may be the result of entrapment of the volar plate or an avulsion fracture in the joint space. Irrigation, debridement, bacterial prophylaxis, and wound closure are indicated for open wounds. ^[16]

For proximal interphalangeal joints, lateral and dorsal dislocations may be treated effectively with closed reduction. Anesthetize the digit by digital or metacarpal block. Metacarpal block may be the preferred technique because a digital block causes further swelling of the injured digit. While holding the phalanx proximal to the injury, apply a distracting force along the longitudinal axis of the digit. While maintaining traction, hyperextend the phalanx (for dorsal dislocations) and bring it back to its normal anatomic position. Inability to reduce a PIP dislocation may be the result of entrapment of the volar plate or an avulsion fracture in the joint space. Consultation with a hand surgeon is required. Thorough physical examination with active and passive range of motion is required after reduction. If the joint remains deviated by more than 20° compared to the unaffected side, surgical referral is indicated. If the joint is stable with active and passive range of motion, 3 weeks of immobilization followed by physical therapy is indicated. Pain and stiffness are likely sequelae and the patient should be forewarned. However, long-term prognosis is good.

For metacarpophalangeal joints, the recommended treatment of complex and volar dislocations is a gentle compression dressing and urgent consultation with a hand surgeon because they are likely to require open reduction. Reduction of simple dislocations of the MCP joint may be attempted by an emergency physician, although reduction often is unsuccessful. Entrapment of the metacarpal head between muscles and tendon on the palmar side of the hand often prevents closed reduction. After administration of a metacarpal or wrist block, flex the wrist to relax the flexor tendons. Flex the proximal phalanx while applying mild longitudinal traction. Use care to avoid hyperextension or excessive longitudinal force, which may open the joint space and allow entrapment of the volar plate. Following successful reduction, immobilize the hand in a planar splint and refer the patient to a hand surgeon.

For the interphalangeal joint of the thumb, evaluation and treatment of thumb IP joint injuries are similar to those for the IP joints of the fingers. After reduction, the joint should be immobilized in 20° of flexion for 3 weeks. For the metacarpophalangeal joint of the thumb, simple dislocations may be reduced following administration of a median nerve block. Flex and abduct the MCP joint and apply longitudinal force to the base of the proximal phalanx.  If this method is unsuccessful, flexion of the IP joint and wrist will relax the flexor pollicis longus tendon, which may be complicating the reduction. Thorough examination is necessary after reduction. If the joint is stable, immobilization of the MCP joint in 20° of flexion for 3 weeks is indicated.

Ligament injuries

For ulnar collateral ligament injuries of the thumb, whenever the history or clinical signs cause suspicion for UCL injury, stability of the collateral ligaments of the thumb must be assessed. Assessment usually requires a median nerve block. Compared to the undamaged side, if the thumb is deviated more than 20° or no firm endpoint to the joint opening can be appreciated, referral is prudent. If the thumb MCP joint is unstable or if a complete UCL tear is suspected, the thumb should be immobilized in a thumb spica splint and the patient should be referred to a hand specialist within a few days. If less than 20° of deviation is present as compared to the normal side and if a firm endpoint is appreciated, immobilization in a thumb spica splint should be undertaken.

Evaluation and treatment of radial collateral ligament injury is the same as for UCL injury.

Tendon injuries

The emergency physician should search carefully for tendon injuries. One British study showed significant deficiencies of emergency physicians in identifying tendon and nerve injuries with hand lacerations. ^[17]

The superficial location of extensor tendon injuries facilitates evaluation and permits repair in the ED. Partial tendon injuries (< 40-50% of the tendon width) usually do not require repair. They should be splinted and follow-up arranged with a hand surgeon.

Complete extensor tendon injuries can be repaired using 4.0 nonabsorbable suture material and a figure 8 or modified Kessler suture, with the knot buried on the palmar aspect of the tendon. However, this procedure does not need to be performed urgently, and closure of the skin, splinting of the hand, and referral to a hand surgeon for delayed repair is often the best option.

Flexor tendons are very sensitive to manipulation and prone to form adhesions. Restoration of a smooth gliding function is essential to future normal use of the hand. For this reason, primary repair should never be attempted in the ED. Repair should be done by a qualified hand surgeon in an operating room equipped for microsurgery.