89 Hand and Wrist Injuries

• Irrigation is the greatest ally in preventing wound infections.

• The final step in the management of almost all hand and wrist injuries is effective splinting.

• All but the most minor hand and wrist injuries merit scheduled follow-up.

Perspective

Effective use of the hand is such a fundamental human skill that none of us can imagine living without it. Injuries that threaten this vital function have an impact on patients of all ages and walks of life but tend to cluster in productive young adults who use their hands to make a living. It goes without saying that the stakes are high for both the patient and physician. Emergency physicians (EPs) must develop a sophisticated understanding of hand anatomy and function, as well as injury patterns and optimal management strategies.

Epidemiology

Annually, more than 16 million people suffer some form of hand injury, and more than 4.8 million will seek treatment of these injuries at the emergency department (ED).¹ Traumatic injuries may include lacerations, fractures, and tendon or ligamentous injuries. Most injuries are readily identified in the ED, provided that the assessment is effective.² Because the morbidity associated with undiagnosed, misdiagnosed, or mistreated hand injuries is significant, a high level of expertise is required of the EP.

Pathophysiology

This chapter assumes that the reader is familiar with the basic structures of the hand. The back of the hand is referred to as the dorsal surface; the palm is called either the palmar or volar surface. The lateral borders of the hand are referred to as radial or ulnar. Movement may occur in any of these planes. Additionally, fingers may abduct away from or adduct toward an imaginary plane bisecting the third finger. The thumb has further planes of movement. In general, we refer to the digits by their numerical designations, but the common names are also acceptable—first (thumb), second (index finger), third (middle finger), fourth (ring finger), and fifth (little finger).

Presenting Signs and Symptoms

When assessing hand injuries, the history should focus on the mechanism of the injury, hand position at the time of the insult, perceived resultant functional impairment, and the time elapsed since the injury. Some mechanisms yield classic injury patterns, such as the jersey finger and mallet finger. Other injury patterns are known for their poor outcomes, such as fight bites or high-pressure injection injuries, and require specific managements. Some wounds are more prone to infection, such as crush injuries and grossly contaminated wounds.

During the history the patient’s hand dominance and career should also be ascertained and documented. Factors that may compromise wound healing, such as smoking, drug use, or an immunocompromised state, are important to document.² Tetanus status should be verified.

Despite its complicated nature, the hand can be examined adequately in a short period. Developing a rapid, reproducible hand examination strategy and performing it regularly will decrease the chance of missing subtle injuries. Even when a specific injury is obvious, it is important to examine the entire hand to avoid overlooking less obvious, coincident injuries. Box 89.1 lists one approach to comprehensive assessment of the hand.

Box 89.1 Two-Minute Hand Examination

General

General appearance

Obvious deformity

Vascular

Hemorrhage control

Ulnar and radial pulses

Capillary refill less than 2 seconds

Neurologic

Ulnar

• Sensation: light touch distal, volar fifth digit

• Motor: interosseous—abduction of the second digit

Median

• Sensation: light touch distal, volar second digit

• Motor: thenar eminence—adduction of the first digit toward the ceiling

Radial

• Sensation: light touch to the dorsal web space between the second and third digits

• Motor: wrist extension, otherwise sensation only in the hand

Digital

• Two-point discrimination—2 to 5 mm at the fingertip

Musculoskeletal

Bony palpation of all digits and joints

Active range of motion: make a fist; fully extend all digits

Passive range of motion: passively take all digits and joints through all ranges

Resistance: test all joints, all ranges with resistance to diagnose partial ligament injuries

Ligamentous

Flexor digitorum profundus tendon—hold the proximal interphalangeal joint in extension; flex the distal interphalangeal joint against resistance

Flexor digitorum sublimis tendon—hold the metacarpophalangeal joint in extension; flex the proximal interphalangeal joint against resistance

Extensor tendons—place the hand palm down; extend the digit with resistance at the nail bed

Ulnar collateral ligament—adduct the thumb against resistance

Assuming that no active bleeding is occurring and requires immediate attention, examination of the hand begins with inspection. All rings, watches, and other potentially constricting devices should be removed immediately.³ Lacerations and other disruptions in skin integrity are usually recognized easily; erythema, soft tissue swelling, and ecchymoses should also be noted. It is important to compare the general position of the hand with that of the unaffected side inasmuch as many fractures or tendon disruptions will cause characteristic deformities that are recognizable on inspection.

Vascular integrity should be determined by comparing skin temperature with that of the opposite hand, feeling for ulnar and radial pulses, and documenting intact and symmetric distal capillary refill.

Neurologic testing should be performed before local or regional anesthesia. Radial, median, and ulnar nerve function should be individually assessed and the digital nerves interrogated via both light touch and two-point discrimination. Comparison with the unaffected side can be useful. To evaluate for radial neuropathy, the dorsal aspect of the second and third web space is tested for decreased sensation. Proximal limb radial nerve lesions will cause wristdrop. However, the superficial radial nerve, as it courses through the hand, is sensory only. To test for median neuropathy, the distal, palmar surface of the second digit is assessed for decreased sensation. Placing the hand dorsal side down and abducting the fifth digit toward the ceiling tests motor function. Resistance is applied to the thenar eminence, followed by palpation, to test for contraction of the abductor pollicis brevis muscle. To test for ulnar neuropathy, the distal, palmar surface of the fifth digit is assessed for decreased sensation. Challenging the interosseous muscles best tests ulnar motor function. One method is to ask the patient to place the injured hand on a surface with the fifth digit down and the thumb pointing at the ceiling. The patient then abducts the second finger (spreads the fingers) against resistance; weakness of the first interosseous muscle verifies contraction.

Musculoskeletal assessment is targeted at identifying injuries to bones, joints, and ligaments. Bone structures should be palpated thoroughly, as should all joints, to look for signs of pain, laxity, and limited range of motion. Every digit and joint should be put through complete active and passive range of motion. All extensor and flexor tendons should be tested individually. Specific tendon function is evaluated by ranging every joint individually. Extensor tendon function is tested by extending all interphalangeal and metacarpophalangeal (MCP) joints against resistance. Flexor digitorum profundus tendon injury limits flexion at the distal interphalangeal (DIP) joint; its presence is confirmed by holding the proximal interphalangeal (PIP) and MCP joints in extension and flexing the DIP joint against resistance. Flexor digitorum sublimis tendon injury limits flexion at the PIP joint. This injury is confirmed by holding the MCP joint in extension and flexing the PIP joint against resistance. False-negative results occur if all the other digits are not held in complete extension. The uninjured thumb will have complete active range of motion without pain and should be able to oppose the fifth digit. Full flexion to a fist and full extension should be normal.

Differential Diagnosis and Medical Decision Making

Fractures of the Hand

Metacarpal Bone Fractures

Metacarpal bone fractures cannot be discussed simply as a single group because of the vast differences in inherent mobility and function among them. For each, the tolerance for unreduced angulation varies. The first metacarpal is very mobile and fractures are relatively uncommon. Management includes proper reduction, placement of a thumb spica splint, and follow-up with hand surgery. The second and third metacarpals are the fixed center of the hand, and proper reduction of fractures is important for full return of function. The fourth and fifth metacarpals are more mobile and have greater ability to compensate for angular deformities. Hand surgery consultation is necessary for all metacarpal fractures; for unstable reductions; for irreducible, open, or intraarticular fractures; and for any fracture with rotational malalignment.

Metacarpal base fractures are uncommon and usually of little significance.² The exception is at the base of the fifth metacarpal bone, where there can be associated subluxation of the metacarpal-hamate joint. The injured hand should be immobilized in an ulnar gutter splint and scheduled for referral to hand surgery.

Bennett/Reverse Bennett and Rolando Fractures

A Bennett fracture is a fracture of the proximal first metacarpal bone (Fig. 89.1). The classic mechanism is an axial load onto a flexed and adducted thumb. For example, a football quarterback strikes the helmet of an opposing player after releasing a throw. In this avulsion injury, the strong abductor pollicis longus muscle fractures the bone at the point of its insertion at the ulnar aspect of the first metacarpal bone. This causes displacement of a bony fragment, which can be seen on a plain film radiograph. It is usually an unstable fracture, and ED management should consist of referral to a hand surgeon and immobilization in a thumb spica splint. Potential long-term morbidity includes malunion, decreased function, and significant arthritis.

Fig. 89.1 Bennett fracture (arrows).

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

The same injury pattern and mechanism of injury can also occur in the fifth metacarpal bone and is called a reverse Bennett fracture, which is as unstable as a Bennett fracture because of the traction exerted by the extensor carpi ulnaris muscle on the distal aspect of the fifth metacarpal. Traction tends to pull the distal segment ulnarly. Closed reduction with ulnar gutter splinting may be attempted, but any articular incongruity must be recognized and referred on an emergency basis to a hand surgeon for potential immediate operative repair.

A Rolando fracture is similar to a Bennett fracture; however, it is comminuted and by definition extends into the joint space. ED management is identical to that for a Bennett fracture.

Boxer’s Fracture

Although many people refer to any fracture of the fifth metacarpal as a boxer’s fracture, the specific injury is a fracture through the neck of the bone (Fig. 89.2). This injury is most frequently seen when a solid object is forcefully struck with a closed fist. True boxer’s fractures may carry significant morbidity because in addition to being an unstable fracture, the injury often has a rotational component. If allowed to heal in this position, the hand will be deformed and weakened.

Fig. 89.2 Boxer’s fracture (arrow).

(From Mettler Jr FA. Essentials of radiology. 2nd ed. Philadelphia: Saunders; 2004.)

ED management consists of an attempt at closed reduction and placement of a dorsal-volar splint. Regardless of the type of splint used, at a minimum the fourth and fifth MCP joints should be splinted at 90 degrees of flexion. Because of the instability of this fracture, all patients should be referred to a hand surgeon and warned of the significant likelihood that the injury will require operative management.

Proximal and Middle Phalanx Fractures

Proximal and middle phalanx fractures are managed similarly. The degree of instability depends on the nature of the fracture. Transverse and spiral fractures have greater instability than simple fractures do and are therefore more likely to require percutaneous fixation. It is important to keep in mind that rotational deformity cannot be tolerated. When the hand is held in a relaxed fist, the fingers should all point to the scaphoid region. Visible deviation from this plane suggests a rotational deformity of greater than 10%. All nondisplaced proximal and middle phalanx fractures should be splinted in the ED and referred for outpatient follow-up. Rotated, transverse, displaced, or intraarticular fractures should be reduced and splinted, and contemporaneous hand surgery consultation should be obtained.

Distal Phalanx Fractures

The most common distal phalanx fracture is a tuft fracture, and nail bed injuries are the most common complication of this fracture.² There is some controversy regarding the need to repair nail bed injuries; however, most authors recommend performing trephination only for nail bed hematomas involving 30% to 50% or greater of the nail bed surface. When the nail bed is involved, tuft fractures are considered open fractures. Although some physicians prescribe antibiotics empirically, evidence suggests that prophylactic antibiotics are not indicated.⁴ Proximal distal phalanx fractures are often unstable and require hand surgeon referral for percutaneous wire placement. An attempt to reduce any rotational deformity or angulation should be made before splinting. Splinting should isolate the DIP joint alone.