ABSTRACT: To determine the stability of the injury, examine phalangeal and metacarpal fractures for intra-articular involvement. Suspect carpal bone fracture in any patient with wrist pain and tenderness; proper splinting is essential to prevent avascular necrosis of the bone, arthritis, and chronic disability. After successful reduction of a distal or proximal interphalangeal joint dislocation, order follow-up x-ray films. Apply stress testing of the joint space to all injured joints to ensure ligamentous integrity. Carpal and carpometacarpal dislocations require immediate consultation with a hand specialist. Therapy for bite wounds includes copious irrigation, debridement (in the operating room if necessary), and antibiotic prophylaxis. A patient with an infected bite wound requires hospitalization and intravenous antibiotics.
Each year, hand injuries on the job or on the playing field force millions of people to seek medical care. Prompt assessment of the damage is essential to promote quick healing while preventing permanent disability.
In this third article of our 3-part series on hand injuries, we offer our approach to managing fractures, dislocations, nail bed injuries, and bite wounds. Our first article focused on the general evaluation of the injured hand and described the specifics of wound care. In the second article, injuries to the nerves, vasculature, tendons, and ligaments took center stage.
Wrist, hand, and finger fractures often accompany many kinds of traumatic hand injuries. Several types of fractures are particularly important, either because of their frequency or because of the seriousness of potential complications if timely diagnosis and treatment are not provided.
Phalangeal and metacarpal fractures are common. With both, it is important to identify any intra-articular involvement. Displaced fractures of phalanges or metacarpal bones that involve more than 25% of an articular surface are generally considered to be unstable; these merit evaluation by a hand surgeon for possible open reduction and internal fixation.1
Phalangeal fractures. Proximal phalangeal fractures are usually accompanied by volar angulation or displacement, and they require accurate reduction and proper splinting.
Using adequate anesthesia, place traction on the distal fragment while it is flexed. In essence, this recreates the injury, thereby reuniting the fractured ends. The angulation of a middle phalangeal fracture is not easy to predict, but apply the same principles of reduction nonetheless. After reducing a phalangeal fracture, place the finger in a splint that extends across the palm to immobilize the metacarpophalangeal joint in 90 degrees of flexion and the interphalangeal joints in 45 degrees to 60 degrees of flexion.
Metacarpal fractures. Because of the tension of the interosseous muscles, these injuries usually angulate dorsally. The boxer's fracture commonly occurs when a patient punches a solid object, such as a wall or an opponent's face. A transverse fracture results at the distal fourth or fifth metacarpal shaft (Figure 1).
Both boxer's and transverse fractures require reduction if the angulation exceeds 30 degrees. Apply pressure on the digits from the volar surface and put counterpressure on the proximal fragment from the dorsal surface. Then immobilize the hand until a hand surgeon can examine the patient (preferably within 3 to 5 days). The ulnar gutter splint, a short plaster arm splint placed along the ulnar region with extension under the phalanx of the involved digit(s), is ideal for this purpose. Position the wrist so that it is held in 15 to 30 degrees of extension while the metacarpal and interphalangeal joints are held, respectively, in 45 to 60 degrees and 10 to 20 degrees of flexion.2
Carpometacarpal fractures. These are of particular concern, especially when the index and little fingers are involved. Rotational deformity at the fracture site often causes overlapping of digits; it may also be identified by the patient's inability to properly clench his or her fist. A hand surgeon is usually required to precisely reduce and internally fixate the bones to ensure correction of the rotational component of the fracture. Splint the injury and see that the patient is examined by a hand surgeon within 3 days.
Carpal bone fractures. Suspect one of these fractures in any patient who presents with wrist pain and tenderness (eg, a "sprained wrist"). Plain radiography is indicated, but since it is not sufficiently sensitive to detect all acute carpal bone fractures, do not rely on it to exclude the diagnosis.
All patients with significant wrist pain and localized tenderness merit a presumptive diagnosis of carpal bone fracture and immobilization in a splint. Immediately refer to a hand specialist any patient who still complains of pain and tenderness after 7 to 10 days, if you have not already done so.
A follow-up plain film at days 7 to 10 will show bony resorption-the first sign of fracture healing-thereby rendering the fracture more visible than it was originally. Inadequately immobilized fracture sites can lead to avascular necrosis of the bone, arthritis, and chronic disability.
In descending order, the 3 most common carpal bone fractures are scaphoid, triquetrum (dorsal chip), and lunate fractures.1
A scaphoid bone fracture results from a fall onto an outstretched hand. Tenderness in the anatomic snuff-box is classic (Figures 2 and 3). Avascular necrosis and nonunion are not uncommon complications of an untreated scaphoid fracture; chronic pain and disability may ensue (Figure 4), leading to an unstable or dysfunctional hand.
A triquetrum (dorsal chip) fracture arises from an injury involving hyperextension and ulnar deviation of the wrist or a direct blow to the wrist. The triquetrum may be fractured transversely, but the fracture usually is minor and affects the dorsal aspect of the bone; it is usually best visualized on a lateral film view (Figure 5). Immobilization with a volar splint in the emergency department and referral to a hand surgeon are recommended.
A lunate fracture also results from a dorsiflexion-related injury; pain and tenderness over the mid-dorsal aspect of the wrist at the radiolunate articulation are characteristic of the fracture. Because plain radiography may not reveal the fracture, base the diagnosis on the clinical finding of localized radiolunate tenderness.
With the patient's wrist and thumb held in a neutral position, place a thumb spica splint on the injured forearm and wrist. Improperly managed, a lunate fracture may lead to avascular necrosis (Kienbck disease) similar to that seen with untreated scaphoid and hamate fractures (Figures 6 and 7). The long-term complication of greatest consequence is loss of wrist stability and proper function.
Distal and proximal interphalangeal joint dislocations. Dislocations in the hand most frequently affect the distal and proximal interphalangeal joints. The distal inter- phalangeal joint is well supported on all sides except dorsally-the usual direction of dislocation. The volar plate is usually disrupted with dorsal dislocations.
Following the initial roentgenographic evaluation, reduce the dislocation by placing the distal phalanx in longitudinal traction and extension of the distal end of the phalanx. Step the proximal end of the dislocated phalanx back into proper alignment with the distal tip of the middle phalanx. Complete the reduction by flexion of the distal tip of the distal phalanx to achieve the proper anatomic alignment of the joint.
Dislocations of the proximal interphalangeal joint usually occur in the dorsal or lateral directions.3 Use the same reduction technique as for the distal interphalangeal joint.
After successful reduction of either a distal or proximal interphalangeal joint dislocation, follow-up x-ray films are necessary, as is stress testing of the joint space to rule out an unstable ligamentous injury. Splinting for 3 to 5 weeks, depending on the extent of suspected ligamentous injury, and immediate referral of patients with unstable ligamentous injuries to a hand surgeon are indicated.
Metacarpophalangeal dislocations. Closed reduction of these uncommon finger injuries is very difficult and should be undertaken only by a physician experienced in their treatment. An ulnar collateral ligament rupture, or gamekeeper's thumb, is easy to miss and thus requires a high index of suspicion, especially when treating metacarpophalangeal dislocations of the thumb. The injury is detected only by stress testing of the metacarpophalangeal joint of the thumb to ensure the integrity of the ulnar collateral ligament at this level.
Carpal and carpometacarpal dislocations. Always rule out these injuries when wrist tenderness or swelling is present, because inappropriate treatment carries the risk of potentially disastrous consequences. The complexities of these dislocations mandate immediate consultation with a hand specialist. Use anteroposterior and lateral x-ray films of the wrist to eliminate the possibility of displaced lunate and perilunate dislocations, and correlate the radiographic and clinical findings (Figure 8).
NAIL BED INJURIES
Both blunt and penetrating trauma to the hands commonly injures the nail bed (Figure 9). When evaluating the injury, first obtain x-ray views of the injured fingers to rule out underlying fracture. Test for function of the flexor digitorum profundus over the distal interphalangeal joint, as we described in the first article of this series.4
If an acute subungual hematoma is present, assume that there is an underlying nail bed laceration. Most nail bed lacerations produce only subungual hematomas or minor wrinkles of the new nail plate as it regrows over time. In these cases, the intact nail plate serves as a stent for the healing nail bed injury, thus promoting a satisfactory result without intervention.
We drain a subungual hematoma that involves more than 25% to 30% of the nail plate area because even small hematomas that are not associated with serious nail bed injury may cause intense pain. You can use a microcautery device to bore a hole through the nail to release the subungual pressure of the hematoma, or you can elevate the free edge of the nail plate with an 18-gauge needle to establish a drainage tract at the distal nail edge itself.
Nail bed repair is indicated when the bed is disrupted by nail plate laceration, fractures of the distal phalangeal tuft, severe crush of the subungual area, and occasionally in the presence of phalangeal tuft fractures. Remove the nail plate itself to obtain access for the repair. Always precede nail removal with an effective digital nerve block. Next, use a small pair of hemostats under sterile conditions to fully separate the nail from the nail bed. Finally, clamp the hemostats at a lateral edge of the nail, and gently roll the hemostats to the opposite side, taking the nail off the nail bed. Be particularly careful not to inadvertently damage any of the nail matrix further.
If the nail matrix was avulsed during the injury, retrieve it from the nail plate and replace it as a graft in the nail bed. Larger pieces of the nail bed may require suturing with 7-0 chromic suture for accurate positioning. This technique often results in the nail bed healing with minimal scarring; however, it is difficult to perform without magnification and special instruments.
Accurate repair of the nail bed laceration with 6-0 or 7-0 absorbable sutures is indicated. If the nail fold is lacerated, use a layered closure to maintain the integrity of the germinal matrix and overlying eponychium; suture the matrix and eponychium independently.
If the removed nail is intact, consider using it as a protective sheath by placing it over the repaired laceration and suturing the proximal and distal ends down to the skin underneath. However, thoroughly scrub the nail with povidone-iodine solution and normal saline beforehand.
If you do not replace the nail plate, insert petrolatum gauze into the proximal nail fold; this prevents premature spontaneous closure of this space during the healing process. Apply a compression dressing, and have the patient wear it for about 2 to 3 weeks. The nail plate stent may be removed after 2 to 4 weeks, depending on the rate of nail regrowth.
Because of the abundant bacteria that thrive as normal flora in the oral cavity, infection is a significant concern when dealing with bite wounds. Moreover, the punctures, crush injuries, and irregular lacerations that result from bite wounds are themselves infection-prone because of the associated tissue destruction. For these reasons, use great caution when managing these injuries.
First, copiously irrigate the wound and thoroughly search for any foreign bodies. Roentgenography may help rule out a fracture or an embedded tooth.
Healing by secondary intention is the ideal way to manage bite wounds. However, if the injury is located in a region of cosmetic importance, consider primary closure following copious irrigation. Debridement in the operating room is indicated when a tendon sheath has been violated, the wound is infected, or an open fracture or joint injury is present.
Familiarize patients with the signs of infection, and advise them to return for follow-up in 24 to 48 hours. We recommend antibiotic prophylaxis with amoxicillin/clavulanate, 875 mg bid for 5 days, to cover the most likely organisms from the offending oropharynx. A patient who does not present until the wound is already infected requires immediate hospitalization and intravenous antibiotics (generally, ticarcillin/clavulanate, 3.1 g q4-6h), since infection can progress rapidly.
Dog bites. The first step is to attend to cleaning and, if necessary, debriding these common injuries. Determine whether rabies and tetanus are a possibility, and administer prophylaxis if necessary.
Organisms commonly responsible for infections in dog bite wounds are viridans streptococci and Pasteurella multocida. We recommend prophylaxis with amoxicillin/clavulanate (875 mg bid for 5 days) or clindamycin (300 mg PO q6h) plus ciprofloxacin (500 to 750 mg PO q12h).5
Cat bites. These have higher rates of subsequent infection than dog bites, and infections are more likely to be caused by P multocida. Whereas most wound infections take 2 to 3 days to develop, Pasteurella infections become clinically evident within 24 hours.
Staphylococcus aureus is another common culprit. For antibiotic prophylaxis, we recommend amoxicillin/clavulanate (875 mg bid for 5 days). Cat bites should rarely, if ever, be sutured, since they are usually puncture wounds and, therefore, highly infection-prone.6
Human bites. The majority of these injuries are sustained while punching someone in the mouth (Figure 10). Sometimes the patient will not offer, or will even deny, a history of this sort.7 Therefore, consider all wounds on the dorsum of the hands as possible human bite wounds. In addition, consider the possibility of coexistent fractures, especially those involving the fourth and fifth metacarpals (boxer's fractures).
A unique organism commonly responsible for human bite wound infections is Eikenella corrodens. Viridans streptococci and Staphylococcus and Corynebacterium species are also often implicated. Start amoxicillin/ clavulanate prophylaxis (875 mg bid for 5 days) as soon as possible.8
Tenosynovitis and deep space abscess formation, which require prompt surgical intervention, are potential complications of bite wounds. Instruct all patients who incur bite wounds to return immediately for surgical evaluation if any signs or symptoms of progressing infection develop. n
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