The following discussion is divided into traumatic and nontraumatic conditions of the hand. Traumatic disorders include soft-tissue wounds, tendon injuries, nerve injuries, vascular injuries, and injuries to the ligaments and joints. Nontraumatic disorders consist of noninfectious inflammatory conditions, constrictive or compressive injuries, and infections of the hand.
It is important to take a thorough history to determine how the injury occurred. The type of wound frequently impacts management decisions. Incised wounds are those caused by a sharp object such as a knife or glass. Although these are usually clean wounds that can be closed primarily, they can be contaminated in certain occupations such as fish-handling.
Puncture wounds must be assessed and treated carefully. Foreign bodies are assumed present and the risk of infection considered high, especially when the puncture occurs secondary to a human or animal bite. Refer to the specific sections in this chapter on human “Fight Bite Injuries” and “Animal Bites” for further details.
Blast wounds are very serious injuries owing to the forceful penetration of foreign objects. Early closure may seal in necrotic tissue as well as foreign material. The first step in treatment is to evaluate nerve and tendon function with careful documentation and local debridement. The hand should be rechecked 36 to 72 hours after injury for final debridement and wound closure in the operating room, because there is a latent period before the impact of the concussive force on the circulation is clinically apparent.
Crush injuries, amputations, and high-pressure injection injuries are discussed later.
To assess a wound, one must have control of bleeding. This is usually possible with the application of a sterile pressure dressing. When this is not feasible, however, proximal control is best achieved by the use of a pneumatic tourniquet (Fig. 11–56A). If one is unavailable, a blood pressure cuff placed in the normal position over the arm can be used, but these may deflate during the procedure. Prior to placing the tourniquet, a precursory evaluation of nerve and tendon function is performed. Cast padding is placed under the cuff and the arm is elevated to improve venous drainage of the limb after which the cuff is rapidly inflated to 250 to 300 mm Hg or 100 mm Hg above systolic pressure. This provides good control of bleeding for 20 to 30 minutes and permits enough time to clean the wound and ligate bleeding vessels.22
A. Pneumatic tourniquet used to stop hemorrhage in a patient with a hand amputation. B. Digital tourniquet using a latex glove and hemostat.
If a single digit is injured and hemostasis is required to repair an injury, a sterile glove can be used by cutting off a latex “digit” and wrapping it around the base of the patient’s finger. The latex is secured firmly using a hemostat (Fig. 11–56B). Alternatively, commercially available finger tourniquets may be used. The amount of time that the tourniquet is applied should be limited.
Local anesthesia with epinephrine injected into the hand and digits will also decrease bleeding. The use of epinephrine in such a manner has been considered taboo since the 1950s. Recent studies using the typical concentrations included with commercially available local anesthetics (1:100,000) have not uncovered a single case of digital ischemia despite thousands of uses.23 Based on these data, epinephrine, in the proper concentration, is safe to use in the digit.
Contamination and Wound Closure
Initial care of the wound includes careful assessment and evaluation of the extent of injury followed by pressure irrigation. An examination of nerve and tendon functions should be performed in addition to direct inspection for tendon or joint involvement (Fig. 11–57). The surrounding skin is cleansed with an antibacterial solution such as povidone-iodine (Betadine). Judicious debridement and removal of foreign material and any nonviable tissue should follow when indicated. The patient’s perception of a foreign-body sensation in a digit or the hand suggests that one is present even if not visualized on radiographs.22
Laceration of the hand involving the joint of the MCP.
Whether or not to close the wound is then decided on the basis of patient factors (e.g., age, diabetes), time since injury, mechanism of injury, and the degree of contamination. A clean wound can be converted to a dirty one by poor care within the ED and a dirty wound can be converted to a clean one by careful debridement and irrigation. The nature of the offending agent must also be considered; wounds from a knife or glass are generally clean, whereas wounds secondary to bites from animals are not. Crush injuries have macerated tissue and are at a higher risk of infection.
Clean wounds have little contamination and can be closed after irrigation with saline. Dirty wounds are cleansed thoroughly, debrided, and delayed closure is preferred if there is any question about continued contamination. The interval between the insult and the time of treatment is rendered, is ascertained, because a delay in seeking care is a risk factor for a wound infection.
Prophylactic antibiotics are not recommended in simple soft-tissue wounds of the hands. The infection rate is no different with or without their use.24,25
Glass, metal, and wood are the most common foreign materials seen in hand wounds (Fig. 11–58). Although some foreign bodies are inert and cause little reaction, others can cause significant problems. On examination, a small laceration or puncture wound with local hemorrhage may be present. The foreign body is usually located within the area of maximal tenderness. All wounds, especially of the hands, should be considered to have a foreign body present until proven otherwise.
Hand laceration with a metal foreign body.
The work-up begins with a plain radiograph. Fluoroscopy may be of benefit for both foreign-body localization and removal. Ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) are more advanced techniques for identification. Refer to Chapter 5 for a full discussion.
Glass is radiopaque.26 Small pieces of glass may not require removal, whereas larger ones tend to migrate and become symptomatic as fibrous reaction envelops them. Metallic particles may remain inert, and if asymptomatic do not require removal. Symptomatic metal fragments may be allowed to remain until a capsule forms around them which facilitates their removal.
Wood and plastic are radiolucent. Ultrasound and CT may demonstrate these substances. Plastic is perhaps the most difficult substance to detect, often requiring MRI. Wood can be inert but is frequently stained with toxic dyes or contains oils or resins that induce an inflammatory response.
If the emergency physician is unable to remove the foreign body, the injured hand should be splinted and the patient referred. Often, waiting several days to explore the area may prove beneficial as small fragments may encapsulate and gradually migrate to the surface.
Subungual Hematoma and Nail Bed Injuries
The fingertip is defined as the area distal to the insertions of the flexor and extensor tendons on the distal phalanx.27 Injuries of the fingertip are classified here as subungual hematoma, nail bed injuries, and fingertip amputations. To assess the fingertip after injury, gauze applied by the patient or in triage must first be removed. When a fingertip or nail bed is adherent to gauze, it can be removed easily by soaking the fingertip in a 1% solution of lidocaine for 20 minutes.28
A subungual hematoma, regardless of the size, does not require nail removal as long as the nail plate is intact.6,7 Trephination of symptomatic subungual hematomas using electrocautery or an 18-gauge needle is recommended (Fig. 11–22).
If the nail plate is lacerated or avulsed, the nail is removed and any lacerations to the nail bed are repaired (Fig. 11–59). If a distal phalanx fracture is associated with disruption or laceration of the nail plate, it is considered an open fracture, but may be treated in the ED.
A. Nail bed laceration. B. Absorbable 5-0 suture is used to approximate the wound edges. C. If the nail plate is unavailable, a single layer of nonadhesive gauze is used to keep the eponychium separated from the nail bed.
The technique for repairing nail bed lacerations includes:
Regional anesthesia using a digital block. The hand is then prepared and draped in a sterile manner.
Using a pair of fine scissors, the nail is dissected bluntly from the nail bed.
With the nail removed, the nail bed laceration is explored and thoroughly irrigated with normal saline (Fig. 11–59A). The nail bed is then sutured using a minimum number of 5-0 absorbable interrupted sutures (Fig. 11–59B). Alternatively, a tissue adhesive (e.g., Dermabond) may be used.
A nonadherent gauze (e.g., Xeroform) or the patient’s recently removed nail is placed back in the nail fold to separate the dorsal roof matrix from the nail bed (Fig. 11–59C). The material is sutured in place with two simple sutures on either side to ensure that it does not dislodge. A tissue adhesive (e.g., Dermabond) has also been used successfully to secure the nail and prevent dislodgement. Separating the bed from the roof prevents the development of adhesions (synechia) that can ultimately result in the regrowth of a deformed nail.
The entire digit should be dressed with gauze and splinted for protection. The outer dressing can be changed as needed, but the material separating the nail bed from the roof matrix remains in place for 10 days.
Prophylactic antibiotics are recommended when there is an associated distal phalanx fracture or significant wound contamination.
Fingertip amputations are classified on the basis of whether or not exposed bone is present. An amputation without exposed bone can be allowed to heal by secondary intention (Fig. 11–60). Management in the ED consists of cleansing the wound and application of a nonadherent (e.g., Xeroform or Vaseline) dressing. When the distal phalanx is exposed, treatment is more complex and may require a Rongeur to trim the bone back. The soft tissue is then sutured so that the bone is no longer exposed, a nonadherent dressing is placed, and the wound is allowed to heal by secondary intention. Consultation with a hand surgeon is recommended if the emergency physician is uncomfortable with the procedure. Prophylactic antibiotics are indicated only in grossly contaminated wounds. Nonmicrosurgical reattachment of a clean, sharply amputated distal tip can be employed as a “biologic” dressing, but the patient should be told that the tip will likely not be viable. In children, treatment is similar except that nonmicrosurgical reattachment has greater success than in adults.27
Other potential treatments include skin grafts, replantation, and flaps. Replantation is an expensive option requiring a surgeon skilled in microvascular techniques. When successful, however, sensation, length, cosmesis, and ROM are preserved, and the incidence of chronic pain is low. Success rates range from 70% to 90% and children do especially well. If the amputation is proximal to the lunula, this is the only procedure that will preserve the nail. Because the amputated tip does not possess muscle, the period of ischemia which allows successful replantation is prolonged (8 hours warm; 30 hours cold).29
Nonetheless, conservative treatment (i.e., healing by secondary intention) alone yields good results in most cases. The authors of studies supporting this approach cite the natural regenerative properties of the fingertip, simplicity, decreased cost, preservation of length, improved cosmesis, low incidence of painful neuromas and stiffness, and good return of sensation. Disadvantages include higher incidence of nail deformity and the need for frequent dressing changes.30–39 Areas of greater than 1 to 1.5 cm2 may require split-thickness skin grafting.
High-Pressure Injection Injuries
These injuries are surgical emergencies and occur to individuals who work with a machine that sprays liquids at high pressure. Examples of such instruments include paint guns, grease guns, concrete injectors, plastic injectors, and diesel fuel jets.40 The nondominant hand is most often affected when the patient attempts to clean the nozzle of the gun while it is still operating.
Initially, the patient may have minimal symptoms and the skin wound is usually small (Fig. 11–61). Despite the trivial wound externally, the emergency physician should be aware that significant tissue injury has occurred below the surface. With time, the extremity becomes swollen, pale, and excruciating pain develops. Severe tenderness to palpation or pain with passive motion is elicited.
High-pressure injection injury to the hand secondary to a paint gun. Note the small entrance wound (arrow). This patient required operative debridement.
Injection injuries may cause extensive loss of tissue, have a high infection rate, and a high rate of amputation. Factors that increase the risk of amputation include the type of material, amount injected, and the pressure of the injection. Oil-based paints appear to be particularly harmful. Injections with water under pressure may be observed in the hospital. A pressure >7000 lb/in2 has been associated with a 100% amputation rate.41 Also, the time to treatment is significant, with some authors suggesting that patients treated in less than 10 hours after the injury fare better than those with delayed treatment.
A radiograph of the extremity should always be performed as it may help to determine the spread of the material and the extent of surgical exploration and debridement necessary. Grease will appear as a lucency.42 Treatment in the ED consists of administering a prophylactic broad-spectrum antibiotic and, if needed, tetanus immunization. High-pressure injection injuries secondary to water can be treated conservatively without surgical debridement in many cases.43 High-pressure injections due to organic solvents, however, are a major source of tissue irritation.44 Not all injuries result in significant injection of foreign material. If there is no tenderness at or around the injection site several hours after the injury, then a significant injection has not occurred and operative intervention is not necessary. Surgery is usually necessary, however, when tenderness is noted proximal and distal to the site of injection. Surgical consultation is required for these cases, and will most often result in irrigation and debridement of necrotic tissue in the operating room.40
Crush injuries to the hand are common. The underlying tissue is congested and ischemic, whereas the surface wounds often appear quite simple and may mislead the emergency physician as to the full extent of the injury. If extensive soft-tissue injury is present, primarily closed lacerations have a high rate of infection. Potential occult soft-tissue injuries include closed tendon ruptures and, in the case of a finger, digital artery injury.45,46 The hand should be placed in a universal hand dressing (Appendix A–5), elevated, and referred to a hand surgeon.22,47
Mangled hand injuries occur secondary to the use of farming equipment, the use of industrial equipment (e.g., punch press), gunshot wounds, motor vehicle collisions, firecrackers, and the use of household equipment (e.g., lawn mowers) (Fig. 11–62).42,48 Treatment of these injuries is difficult. Only a precursory assessment of the extremity circulation and gross neurologic assessment is performed in the ED. Preliminary radiographs are obtained and the hand should be covered with sterile dressings and immobilized while awaiting patient transfer or the consultation of a hand surgeon.
Mangled hand injury following a firecracker exploding in the hand.
Blind clamping of vascular structures should never be performed. If direct pressure does not work, the hand should be elevated and a blood pressure cuff applied proximal to the zone of injury and inflated to a pressure 100 mm Hg above systolic pressure. Immediate surgery is needed when external hemorrhage cannot be controlled.
Pain control with parenteral narcotics or regional anesthesia is usually warranted. Prophylactic broad-spectrum parenteral antibiotics are indicated.48 Tetanus prophylaxis is administered as needed. Operative replantation to salvage the amputated portion can be attempted and has become increasingly more successful with the evolution of surgical techniques and instruments.49
Hand injuries associated with the use of snow blowers and lawn mowers are generally less severe, but seen more frequently.50–52 Injuries occur to the dominant dorsal side of the hand and fingers in almost all cases with extensive lacerations and contusions. Usually, the long and ring fingers are injured. The majority of these injuries can be managed in the ED, although some require operative intervention for debridement and repair.50
A degloving injury occurs when the soft tissue of the hand or digit is separated from the underlying bone. In a “pure” degloving injury, the tendons, bones, and joints remain intact and only the skin is removed. This is often called a ring injury because the ring finger is the most commonly involved digit when jewelry becomes hooked and torn from the digit.53 Treatment includes replantation when the degloved skin is available and the vessels are not damaged. If unsuccessful, secondary reconstruction using a skin flap is required.54,55
Amputation of the hand or finger is not common. Care of the stump includes achieving hemostasis first. Point control of a bleeding vessel with a pressure dressing is usually the initial method. Proximal tourniquets are discouraged unless being used for temporary control or in a patient with life-threatening bleeding. Use for more than 3 hours may lead to irreversible ischemia. Blind ligation or clamping may lead to unnecessary damage to the nerves or vessels.56 Prophylactic antibiotics and tetanus are indicated.
Care of the amputated part involves gentle cleansing if heavily contaminated, wrapping in saline soaked gauze, and storage in a sealed plastic bag. The bag is then placed into another bag filled with ice water (Fig. 11–63). Properly maintained digits have approximately 12 hours of viability.
Proper storage of an amputated part requires that the tissue is wrapped in moist gauze, placed in a bag, and then placed in another bag full of ice water.
The classic indications for replantation include amputation between the PIP and DIP joints, thumb, multiple digits, children, midpalmar amputation, and wrist or forearm (Fig. 11–64). However, all amputated parts proximal to the fingertip should be considered for replantation, and consultation with a hand surgeon should occur. Success is not only related to viability, but also the restoration of a functional hand. It should always be emphasized that the replanted digit will never function normally, and will likely have some sensory problems, as well as chronic stiffness and weakness.
A. Thumb amputation between the MCP and IP joints. B. Hand amputation. Both of these amputations were replanted.
Hand Compartment Syndromes
Acute compartment syndrome of the hand is a relatively rare phenomenon that occurs when the tissue pressure within an enclosed space is elevated to the extent that there is decreased blood flow within the space, decreasing tissue oxygenation. This syndrome is most often a result of a traumatic condition, but nontraumatic entities such as an infectious process may also be causative. The most common causes include fractures, crush injuries, burns, major vascular injury, prolonged hand compression, and iatrogenic injuries such as a cast or compressive dressing.
There are a total of 10 compartments within the hand (Fig. 11–65).57 The volar and dorsal interosseous muscles are enclosed in fascia between the metacarpals. These compartments constitute 7 of the 10 hand compartments—4 dorsal interosseous and 3 volar interosseous compartments. The remaining three compartments comprise the thenar muscles, hypothenar muscles, and the adductor pollicis muscle.
Cross section of the palm, through the metatarsal shafts, showing the compartments of the hand.
The clinical findings are similar to those of other compartment syndromes in the body: disproportionate pain, which is increased on passive muscle stretch and unrelieved by immobilization. The intrinsic interosseous compartments of the hand are tested individually to adequately exclude a limited syndrome. Note that passive stretching of the muscle should occur in the direction opposite to the muscle’s normal actions. The volar interosseous muscles are tested by passive abduction of the second, fourth, and fifth digits. The dorsal interosseous muscles are tested by passive adduction of the second and fourth digits, in addition to medial and lateral movements of the third digit. When testing these interosseous compartments, the MCP joint is placed in full extension and the PIP joint in flexion. The adductor compartment is tested by palmar abduction of the thumb, thereby stretching the adductor pollicis muscle. In a similar manner, the thenar and hypothenar compartments are stretched when the examiner radially abducts the thumb (thenar) and extends and adducts the small finger (hypothenar).57
Compartment pressure measurements provide more objective information and are used in conjunction with clinical findings. Measurements can be taken using a Stryker device or the infusion technique.58 The needle is inserted on the dorsal surface of the hand between the metacarpals to measure the interosseous compartment pressures. For the remaining three compartments, a palmar approach is preferred. Compartment pressure measurements within the hand are difficult and best performed after consultation with a hand surgeon.
Left untreated, compartment syndrome within the hand will result in muscle necrosis and fibrosis. The function of the hand will be severely limited with significant contracture deformities at both the PIP and MCP joints. For more details regarding the diagnosis and treatment of compartment syndromes, refer to Chapter 4.
Open tendon injuries usually result from a sharp object that lacerates the skin and underlying tendon. Evaluation of a tendon in this setting should include an examination of the function of the tendon as well as a visual examination of the tendon within the wound. There are many pitfalls to the diagnosis of open tendon injuries.
The functional assessment of the flexor and extensor tendons is presented at the beginning of this chapter. Further tips to properly diagnose tendon injuries in the face of skin laceration are provided below.
When examining a tendon, always test both active motion and strength (against resistance). In both partial and complete tendon lacerations, tendon motion may be preserved and the only clue to the diagnosis is loss of strength. For partial lacerations, a tendon may have 90% of its width transected and still have normal motion. Therefore, to adequately assess a tendon for injury, one must test motion against resistance.
In lacerations to the dorsal surface of the hand, several pitfalls exist:
Lacerations over the PIP joints and the MCP joints may transect the central slip of the extensor tendon and the diagnosis is not made until the hood mechanism decompensates and leads to deformity.
Disruption of an extensor digitorum communis tendon proximal to the juncturae tendinea may preserve some finger extension due to the function of the other extensor digitorum communis tendons.
The index and little fingers each have two extensor tendons. Finger extension may be preserved when there is laceration to only one of the tendons.
The intrinsic muscles of the hand can extend the PIP and DIP joints despite an extensor tendon laceration.
In lacerations to the flexor surface of the hand, finger flexion may be preserved despite complete disruption of the flexor digitorum superficialis as long as the flexor digitorum profundus is intact. In this scenario, strength will be limited.
Control of bleeding and good lighting is required to obtain an adequate examination. When the skin wounds are small, the tendon may be difficult to locate and the skin must be stretched with a hemostat for proper visualization. In larger lacerations, the tendon injury may be overlooked in the face of other more obvious injuries. Lastly, patient cooperation is essential and is often lacking, particularly in the intoxicated patient.
In open wounds, an incomplete injury to the tendon is common and may be difficult to assess. The position of the hand when the injury occurred is important to determine. If the volar aspect of the hand is lacerated while the fingers are held in flexion, then a partial injury to the flexor tendons will be distal to the skin wound if the hand is examined in extension. However, if the hand were in the extended position at the time of injury, the tendon injuries would lie at the wound edges with hand extension. Therefore, when a tendon is visualized at the base of a laceration, its surface should be inspected while the fingers undergo a full range of motion.
Axiom: A negative examination of a patient with a suspected tendon injury should always be reevaluated to be certain of the diagnosis, particularly in the uncooperative patient.
In lacerations to the hand where tendons are transected, the expected outcome is determined to a large extent by how dirty and complex the wound is. Adhesions are accentuated by touching the tendons or even by blood extravasation around the tendon. Therefore, every attempt is made to avoid unnecessary manipulation of the injured tendon.
In general, definitive repair of an open complete tendon injury can be performed primarily, delayed primarily, or secondarily. Over the past 30 years, the length of time that a tendon can be repaired primarily has been gradually extended.59 There is no conclusive evidence that suggests that immediate repair results in better clinical outcome than delayed primary repair (within 7 days of injury).59,60 A secondary repair is performed after edema has subsided and the scar has softened, usually more than 4 weeks after injury. Secondary tendon repairs result in worse functional outcome.
Delayed primary repairs are performed when other trauma exists and repair of the hand must be deferred or the wound is not optimal for repair because of infection or swelling. Secondary repairs are performed when associated injuries compromise the patient or wound complications are likely.
Partial Tendon Lacerations
Open partial tendon injuries can be splinted without surgical repair. Controversy exists as to the best treatment of partial tendon injuries and therefore consultation with a hand surgeon is recommended.61 Some hand surgeons repair flexor tendons that have injury to >50% of the tendon surface, although little evidence supports this practice. The perceived benefits include avoiding future entrapment, rupture, or triggering. Even less evidence exists regarding the best treatment of partial extensor tendon injuries and therefore many adopt the same principles as flexor tendons—repair of extensor tendons with >50% of the surface lacerated.2 There is some evidence that partial tendon lacerations, regardless of the percentage of tendon injury, heal well without sutures, as long as a portion of the tendon is apposed.62
For partial extensor tendon injuries, the position to splint the hand is important and contrary to routine practice. With these injuries, the hand is splinted with the MCP joint in full extension to avoid additional strain on the already injured tendon. The digit should remain in this position for 3 to 4 weeks, and then slowly returned to full flexion. Partial flexor tendon injuries are splinted in the position of function with the MCP joint at 50 degrees of flexion and the IP joints at 20 degrees of flexion for 3 to 4 weeks.
Flexor Tendon Lacerations
Flexor tendon injuries have been categorized into five zones in order to assist in planning treatment (Fig. 11–66).
Flexor tendon laceration classification.
Zone I extends from the distal insertion of the profundus (FDP) tendon to the site of the superficialis (FDS) insertion. Injuries here generally result in the proximal tendon retracting.
Zone II injuries are in the area often referred to as “no man’s land” because these injuries are very difficult to repair and previously were treated with secondary grafting.63 Unfortunately, they are the most commonly seen flexor tendon lacerations in emergency medicine and technically the most difficult to repair.64 The profundus and superficialis tendons interweave closely and injuries here may injure the vinculum providing the blood supply to the tendons. Repairs in this area are quite complex and should be attempted only by a qualified hand surgeon.
Zone III injuries extend from the distal edge of the carpal tunnel to the proximal edge of the flexor sheath. These injuries generally have a good result with primary repair.
Zone IV injuries include the carpal tunnel and its related structures. Injuries here require careful exploration for associated injuries.
Zone V flexor tendon injuries are those that occur proximal to the carpal tunnel. In zone V injuries, it is essential that the surgeon has adequate exposure and conducts an exhaustive search for major structures that are injured.
Patients with complete flexor tendon injuries require consultation with a hand surgeon for repair within the operating room (Fig. 11–67). Complete flexor tendon lacerations are usually repaired within 12 to 24 hours, although this timeframe can be extended and may be dependent on your institution or the individual surgeon.2 Following repair, the hand is splinted with extension blocked.
A. This patient sustained flexor tendon lacerations zone I (2nd digit) and zone II (3rd digit). B. When flexion was tested, it was clear he had lacerated the FDP of the 2nd digit (unable to flex at the DIP joint while maintaining PIP flexion) and both the FDP and FDS of the 3rd digit (unable to flex finger at all).
Extensor Tendon Lacerations
A classification system used to divide extensor tendon injuries into eight zones and aid in treatment decisions has been devised by Kleinert and Verdan (Fig. 11–68).64–66 The zones of injury are remembered more easily if the physician considers that starting at the DIP joint (zone I); odd-numbered zones are over joints and even-numbered zones are over bones (Fig. 11–69). The thumb is numbered in a similar fashion into five zones.
Extensor tendon laceration classification.
This patient sustained a zone V extensor tendon laceration. Note the flexed resting position of the digit compared to the other digits.
Zone I injuries are over the distal phalanx. Treatment of open zone I injuries involves repair of the tendon laceration if loss of extension is present at the DIP joint. A dorsal splint is applied maintaining the DIP joint in extension for 6 weeks. During this time, the PIP and MCP joints are allowed to move freely.67
Zone II injuries are over the middle phalanx. The treatment here is identical to that for zone I injuries.
Zone III is over the PIP joint. These injuries can be either open or closed, with the central tendon being the most commonly injured structure in both scenarios. This injury frequently leads to a boutonniere deformity if untreated. Open injuries are treated with primary repair and splinted with the wrist in 30 degrees of extension, the MCP at 15 to 30 degrees of flexion, and the PIP in a neutral position. Zone III injuries are associated with a high rate of associated injuries (80%) and generally have a poor outcome.66 These injuries should undergo primary repair by a hand surgeon.
Zone IV injuries include the area over the proximal phalanx. These injuries are treated with primary or delayed repair with a volar splint for 3 to 6 weeks, as described for zone III injuries. A high rate of complications and associated injuries are noted with zone IV tendon lacerations.66
Zone V injuries are over the MCP joint. When from a human bite, the wound must be explored, thoroughly irrigated, and left open. If the joint capsule is not injured and the wound is not secondary to a human bite, it can be repaired with 4-0 or 5-0 absorbable suture. Following repair, the finger should be splinted with the wrist in 45 degrees of extension and the MCP joint in a neutral position.
Zone VI injuries involve the extensor tendons over the dorsum of the hand. The extensor tendons are very superficial in this zone and even apparently minor wounds may involve the tendons. Following repair, 4 weeks of immobilization is required with the wrist at 30 degrees of extension, the MCP joint in a neutral position, and the DIP and PIP joints free. Tendons at this site tend not to retract because they are connected to adjacent structures and tendons. On the dorsal hand, lacerations causing extensor tendon rupture will often lead to adhesions.53
Zone VII injuries occur over the carpal bones and are uncommon. These lacerations often involve the extensor retinaculum and are at risk for developing adhesions after repair. A volar splint is applied with the wrist in 20 degrees of extension and the MCP joint placed in neutral position. These injuries should undergo primary repair by a hand surgeon.64
Zone VIII injuries involve the extensor tendon at the level of the distal forearm and are usually a result of deep lacerations. The tendon may retract due to the elasticity of the musculotendinous junction. These injuries should undergo primary repair by a hand surgeon. A volar splint is placed with the wrist in 20 degrees of extension and the MCP joint placed in neutral position.
Most open extensor tendon lacerations are repaired by an experienced hand surgeon. Successful repair can be accomplished either immediately or after a delay of up to 7 days following the injury. 66 After 7 days, the tendon ends retract or soften. If the tendon will not be repaired on the day of presentation, the wound should be irrigated and debrided, the skin closed loosely with simple interrupted sutures, and the hand splinted, as previously described. Prophylactic antibiotics are prescribed.
The emergency physician may choose to repair certain extensor tendon lacerations if they have the skill and experience to do so. Zones IV, V, and VI tendon lacerations without joint involvement, bony fracture, or human bite wounds may be sutured using a mattress, figure-of-eight, or modified Kessler or Bunnell stitch. Nonabsorbable, 4-0 or 5-0 suture is recommended. Following repair and splinting, the patient is referred to a hand surgeon to initiate a rehabilitation program.
Great forces are required for a closed injury to cause tendon rupture. Closed tendon injuries are the result of either a blunt impact or an opposing force sustained by a contracting muscle-tendon unit. Forces acting against the tendon while it is contracting may avulse the bone at the insertion of the tendon or rupture the tendon without bony injury. Closed tendon injuries are easily missed and, unfortunately, chronic deformities often result if they go untreated.
An avulsion injury of the FDP tendon is called a jersey injury, named because it often occurs when an athlete grabs an opponent’s jersey. The mechanism of injury is forceful extension of a flexed DIP joint. Although rare, this injury is the most common closed flexor tendon injury.46 The index finger is involved in 75% of cases, but any finger can be affected.68 On examination, a subtle flexion deformity is noted at the DIP joint and the patient will be unable to flex the distal phalanx when the PIP joint is extended (Fig. 11–70). If this injury goes untreated, a flexion contracture at the PIP joint may result or the patient will complain that he/she is unable to make a fist.46 A radiograph is obtained to assess for an avulsion fracture. In the ED, the patient should be splinted using a dorsal splint with 30 degrees of wrist flexion, 70 degrees of MCP flexion, and 30 degrees of IP flexion. A jersey finger is best treated surgically.69 Referral to a hand surgeon is needed within 7 to 10 days.46
Jersey finger. The normal cascade of flexion is disrupted. In this patient, flexion at the DIP joint of the fifth digit is absent. (From Brunicardi FC, Andersen DK, Billiar TR, et al. Schwartz’s Principles of Surgery. 8th ed. © New York, NY: McGraw-Hill; 2005.)
A mallet finger is a flexion deformity at the DIP joint in which there is incomplete active extension of the DIP joint (Fig. 11–71). This injury is usually sustained from a sudden blow to the tip of the extended finger. The insertion of the extensor tendon may be avulsed or there may be an avulsion fracture of the distal phalanx with the tendon still attached. For this reason, a radiograph of the finger should be obtained. Acutely, the patient will have minimal pain and little functional disability. The classic flexion deformity may not be present until several days post injury.
A mallet finger deformity (A) without associated fracture (B).
Treatment is to splint the DIP joint in extension (Fig. 11–27). Hyperextension, as has been previously suggested, is avoided. In addition, the patient is allowed to have normal range of motion at the PIP joint. The splint remains in place for 6 weeks. If the splint is removed at any time during this treatment period and the DIP joint is allowed to flex, another 6 weeks of immobilization is warranted. In patients who use the hand a great deal and depend on finger motion at their fingertips, plaster immobilization may be recommended. If left untreated, a flexion deformity of the DIP joint is seen when the PIP is extended and is called a mallet finger. Occasionally, a chronic mallet finger will develop into a swan-neck deformity of the digit.70
Disruptions of the central slip of the extensor tendon at the dorsal base of the middle phalanx should be identified because failure to do so may result in a boutonniere deformity of the digit (Fig. 11–72). Central slip disruption can be caused by three closed mechanisms: deep contusion of the PIP joint, acute forceful flexion of the extended PIP joint, or palmar dislocation of the PIP joint. Thus, one should suspect this injury whenever one encounters a painful swollen PIP joint with any of the aforementioned mechanisms.
The boutonniere deformity. A. The lateral bands of the extensor tendon slip volarly and cause PIP flexion and DIP extension. B. Clinical photo.
On examination, extension at the PIP joint is tested. A 15- to 25-degree loss of extension with decreased strength against resistance should make one suspect this injury. Tenderness at the PIP joint is maximal over the central slip on the dorsal aspect of the PIP joint.
The boutonniere deformity (flexion of the PIP joint and hyperextension of the DIP joint) may be present acutely, but usually does not show up for 7 to 14 days following the injury. Gradually, the lateral bands stretch and slip volar to the axis of the PIP joint, and become flexors of the PIP joint.
Ultrasound, performed by experienced providers, has proven useful in diagnosing these injuries.71
The treatment is to keep the PIP joint in constant and complete extension, while the DIP and MCP joints are allowed to move freely.53 Referral to a hand surgeon is indicated as operative repair is required in some cases.
A traumatic blow to the dorsal aspect of the MCP joint may result in rupture of the extensor hood. 72,73 This injury is also referred to as “boxer’s knuckle” or “boxer’s finger” because it is commonly associated with blunt trauma seen with the act of punching. The extensor tendon injury is disruption of the peripherally located sagittal bands that hold the longitudinal central tendon in place. When rupture of these fibrous bands occurs, the result is subluxation of the tendon either ulnarly (common) or radially (Fig. 11–73 and Video 11–2).
Boxer’s finger. Note the ulnar position of the extensor tendon as it passes the MCP joint.
On examination, marked swelling, decreased joint mobility, and extensor lag are seen. Subluxation of the extensor tendon is made worse by joint flexion and a palpable defect is noted at the site of the sagittal band rupture. The tendon may relocate, causing pain at the MCP joint, as the finger is extended.
Surgery is almost universally successful, but a trial of conservative management with splinting may be attempted. The emergency physician should bring the MCP joint into extension until the tendon relocates, and then the hand is splinted in that position. Other injuries to the MCP joint to be included in the differential diagnosis include contusions, synovitis, collateral ligament ruptures, articular fractures, and capsular tears.72
Three nerves supply the hand with sensory and muscular branches: radial, ulnar, and median. The sensory innervation of the ulnar nerve is very constant whereas others vary. Of all the sensory nerves, the significance of the median nerve is the most important to normal hand function, whereas the radial nerve is the least significant with regard to sensory distribution.
There are varying degrees of nerve injury. In a neurotmesis, the nerve is completely disrupted. This is due to penetrating trauma or a fracture fragment. In an axonotmesis, there is variable motor and sensory dysfunction. In these patients, the proximal and distal ends of the nerves are separated; however, the Schwann cells are maintained. In a neurapraxia, there is no loss of continuity of the nerve and dysfunction is temporary.
Nerve injuries can result from contusions, lacerations, and puncture wounds to the hand. Check for nerve function in every hand injury to avoid delay in diagnosis. Contusions usually result in a neurapraxia with no loss of continuity of the nerve, in which case function is usually regained and treatment is simply observation. Lacerations can result in an axonotmesis or a neurotmesis.74
Lacerations of the ulnar nerve at the distal forearm and wrist result in hypothenar muscle weakness, loss of finger abduction, adduction (interosseus muscles), and flexion, as well as adduction of the thumb. Sensory loss at the tip of the fifthth digit is typical of ulnar nerve dysfunction. Laceration of the ulnar nerve in the proximity of MCP joints of the thumb, ring finger, and middle finger will result in loss of finger abduction and adduction, weakness of thumb flexion, and adduction, while the hypothenar muscles and ulnar sensation remain intact. Deep volar hand lacerations of the MCP joints can cause isolated injury to the digital nerves and distal sensory loss with normal motor function.1
The specific signs of ulnar nerve injury are as follows:
Loss of sensation at the tip of the fifth digit
Deformity of the hand such as Duchenne sign (clawing of the ring and little fingers)
Inability to actively adduct the little finger
Hyperflexion of the IP joint of the thumb on a powerful pinch (Froment sign) (Fig. 11–9)
Intrinsic and hypothenar muscle paralysis with muscle wasting and loss of digital abduction and adduction may also occur. Bouvier’s sign, the inability to actively extend the IP joint on passive flexion of the MCP joint, is also present.75
Ulnar neuropathy in bicyclists is a common overuse injury. Patients experience insidious onset of numbness, weakness, and loss of coordination in one or both hands, usually after several days of cycling. The most common sites are the ring and little fingers on the ulnar side. To prevent this problem, cyclists should wear padded gloves and a pad on the handlebars. In addition, the top bar of the handlebar should be level with the top of the saddle. If symptoms continue, these individuals must stop riding.
The radial nerve supplies little sensory innervation to the hand and its motor contribution is primarily wrist extension. Refer to Chapter 8 for further discussion of radial nerve injury.
Lacerations to the motor branches of the median nerve require repair by a hand surgeon. Median nerve injury commonly occurs at the wrist. Refer to Chapter 8 for further discussion of median nerve injury.
Neuromas are composed of disorganized axons interwoven with scar tissue. They may be quite painful, particularly when they occur over pressure points. Neuromas usually occur after injury to the nerve when the nerve remains intact. Neuromas may follow years after an injury. When the sensory branches of a nerve are involved, neuromas can be very painful and often enlarge insidiously.
The most common sites of neuromas are the sensory branches of the radial nerve at the distal third of the forearm and the wrist. A neuroma in this area may follow trivial trauma that the patient may not recall. Other common sites are the main median nerve, the palmar cutaneous branches at the wrist, and the main ulnar nerve with its dorsal sensory branches to the wrist. The treatment usually depends on how symptomatic the patient is and may include surgical intervention.
Vascular injury is often caused by repetitive trauma. The ulnar artery is susceptible to injury at the segment between the distal margin of the tunnel of Guyon and the palmar aponeurosis where the superficial palmar arch begins. Repetitive impact among baseball catchers, touring cyclists, and handball players may cause an aneurysm with either thrombosis or vascular spasm. Symptoms of vascular injury include one or more cold digits, pain, intermittent mottling, and stiffness. An aneurysm may present with a mass.76
Ligamentous Injuries and Dislocations
Ligamentous injuries to the hand are very common and often missed. The consequence of these injuries is chronic joint stiffness, pain, and swelling.
Collateral Ligament Injury
The collateral ligaments provide support against lateral displacement of the joints of the finger. On examination, one will note ecchymosis or localized tenderness to one or both sides of the IP joint. A vital part of the assessment is to check stability by lateral stress tests (Fig. 11–74 and Video 11–3) and active motion at the IP joints and the MCP joints of the hand. Stable joints that are painful on lateral stress testing indicate a partial tear or sprain of the collateral ligaments supporting the joint.
Video 11-3: Wide opening indicates that the collateral ligament and the volar plate are both ruptured.
The lateral stress test is performed by holding the phalanx on either side of the joint and attempting to open the joint. Minimal opening indicates that the collateral ligament is ruptured on that side.
In performing a stress test of the collateral ligaments of the digits, one must always compare the same joint on the opposite hand. Minimal opening of a few millimeters with a good end point indicates that the collateral ligament is ruptured but that the volar plate is intact. If one notices wide opening on stress testing, the volar plate must be ruptured because of the boxlike nature that the collateral ligaments and volar plate form around the joint (Fig. 11–75). Thus, wide opening indicates that both the collateral ligament and volar plate are ruptured. Wide opening of the joint should be treated in a gutter splint and referred for assessment by a hand surgeon to determine whether surgical repair is necessary. Functional stability is evaluated by active motion. If the patient cannot perform motion due to pain, or stress testing is limited by pain, a digital block will facilitate the examination. Supplemental stress radiographs may be helpful in difficult cases.
The collateral ligaments on either side of the joint and the volar plate form a boxlike support around the joint.
If a partial tear is indicated by appropriate stress testing, as previously described, the treatment is rest with complete immobilization for 10 to 14 days in a malleable finger splint (Appendix A–2). Immobilization should be with the PIP joint splinted at 30 degrees of flexion and the MCP splinted at 45 degrees of flexion. When the thumb MCP is involved, it should be splinted in 30 degrees of flexion. After immobilization of the involved digit, active motion is encouraged for the remainder of the hand.
Capsular thickening and chronic swelling of the involved joint at the end of the immobilization period suggests the initial damage was greater than at first thought and that more protection is needed. This should be provided by buddy (dynamic) splinting the digit to the adjacent normal one for 5 to 7 days (Appendix A–2). The problem at this point is no longer instability, but stiffness, decrease in range of motion, and pain at the involved joint. Swelling may persist for several weeks after a sprain to the finger joints.
Acute complete ruptures require splinting for 3 to 5 weeks with the joint flexed 35 degrees followed by guarded active motion with buddy splinting for protection for an additional 3 weeks.77 Some authors prefer surgical repair of unstable injuries. Consultation with an orthopedist is indicated.
Distal Interphalangeal Joint Injuries
The DIP joint is stabilized by strong collateral accessory ligaments laterally and the fibrous plate volarly. Dorsal support is minimal and includes the extensor mechanism that blends with the dorsal capsule. The collateral ligaments are thick, rectangular bands that arise laterally from the condyle and pass distally and volarly to insert into the volar lateral articular margin and the volar plate. The volar plate provides support to the distal joint and is square shaped and 2- to 3-mm thick.
Disruption of these ligamentous structures is only clinically important if it produces joint instability, which can be assessed by active motion and lateral stress testing. These tests are most valid under digital anesthesia after the reduction of a dislocation. If reduction is maintained through full range of motion, then adequate ligamentous support can be assumed and only 10 to 14 days of immobilization is needed. If, however, displacement occurs in the last 15 degrees of joint extension, then major disruption must be assumed and immobilization in 30 degrees of flexion for a full 3 weeks is indicated.
Dislocations are most commonly dorsal (Fig. 11–76). Reduction is by simple longitudinal traction and manipulation into its normal position (Video 11–4). Reduction is usually without complication; however, irreducible dislocations due to soft-tissue entrapment have been reported.78,79
Dorsal dislocation of both the PIP and DIP joints.
Proximal Interphalangeal Joint Injuries
The integrity of the PIP joint is maintained by the two collateral ligaments on either side and the volar plate on the volar aspect, which together form a boxlike support around the joint (Fig. 11–75). For instability to occur at the joint, there must be disruption of two of these three supporting structures. The PIP joint is prone to develop stiffness after injury, even with good immobilization, and this complication should be communicated to the patient.
There are three types of injuries that occur at the PIP joint:
Dislocations: dorsal (common), volar (rare), and lateral
Volar plate injuries
Lateral dislocations are classified as collateral ligament injuries (rupture) because spontaneous reduction is the rule here. Dorsal dislocations of the PIP joint are quite common, whereas volar (palmar) dislocations are rare (Fig. 11–77). Volar dislocations are invariably associated with disruption of the central slip of the extensor tendon from its insertion at the base of the middle phalanx.80
Volar dislocation of the PIP joint of the finger.
Dorsal dislocations are caused by hyperextension of the PIP joint such as occurs when the outstretched finger is struck by a ball. For this injury to occur, there must be rupture of the volar plate or collateral ligaments. Lateral dislocations are caused by abduction or adduction stresses to the finger, usually while it is in the extended position. The radial collateral ligament is more commonly injured than the ulnar collateral. Volar dislocations are caused by a combination of (1) varus or valgus forces causing a rupture of the collateral ligament and the volar plate and (2) an anteriorly directed force displacing the base of the middle phalanx forward and rupturing the central slip of the extensor mechanism.
Acute swelling and pain may camouflage a dislocation; however, this is not often the case and the deformity is usually obvious. A radiograph of the digit should be obtained before reduction is performed. Following reduction, the emergency physician should examine the collateral ligaments and the volar plate by stress testing to assess the full extent of the injury.
If there is suspicion of rupture of the collateral ligament or a questionable examination, stress views may be taken and compared with the normal side.
Dorsal dislocations are reduced by longitudinal traction and manipulation back to its normal position (Fig. 11–78 and Video 11–5A and B). This may require some initial hyperextension, which avoids entrapment of the torn volar plate. If the joint is stable, after reduction, then early motion (dynamic splinting) is indicated after an initial period of immobilization. If unstable, then it is splinted for 3 weeks with the PIP joint in 15 degrees of flexion, after which an extension block splint should be used for an additional 3 weeks.
Video 11-5a: Lateral PIP joint reduction.
Video 11-5b: Open dorsal PIP joint dislocation reduction.
A. Interphalangeal joints are reduced by gentle longitudinal traction and manipulation back to its normal position. Frequently hyperextension is used initially to avoid trapping the volar plate.
Volar dislocations are usually easily reduced, but are commonly associated with a boutonniere deformity, which results when the central slip ruptures. The volar plate or collateral ligament may also be injured. Because surgical intervention may be needed, referral is indicated.81
Irreducible dislocations are uncommon, but may occur with any of the aforementioned dislocations. In most cases, soft tissue or a bony fragment becomes interposed in the joint space and blocks reduction of the dislocation.82,83 This is suspected in any case in which one or two attempts at reduction prove unsuccessful. These cases may require open reduction to extract and repair the interposed ligament, tendon, or volar plate.
Open dislocations require antibiotic therapy and thorough debridement (Fig. 11–79). One study of 18 open dislocations of the PIP joint suggested that these injuries are best cared for in the operating room because treatment in the ED is associated with a poorer prognosis.84 Repair of the collateral ligaments and reattachment of the volar plate are performed as needed.
Open dorsal dislocation of the proximal IP joint.
The complications of PIP joint injuries and dislocations are restricted joint motion, which is a common sequel. The most common complication is persistent thickening of the PIP joint. Volar plate and collateral ligament instability are further problems.
PIP Joint Volar Plate Injury
The volar plate of the PIP joint may be ruptured when a blow occurs at the end of the finger, causing a hyperextension force. The volar plate may be torn from its distal attachment at the base of the middle phalanx, and a small piece of bone may be avulsed with it.
Injuries to the volar plate will cause a hyperextension deformity at the PIP joint on extension of the finger, whereas pain and catching or locking is noted with flexion of the digit. If the hyperextension deformity is severe, the patient may have a compensatory flexion deformity of the DIP joint secondary to the action of the FDP tendon (swan-neck deformity). Maximal tenderness is observed over the volar aspect of the finger joint, and pain is increased on passive hyperextension and relieved by passive flexion. In addition, there is loss of the normal end point of finger extension provided by an intact volar plate. To perform an adequate examination, a digital or metacarpal block is usually indicated.
Radiographs in patients with a volar plate avulsion may reveal a small bone fragment avulsed from the base of the middle phalanx.
Volar plate injuries are treated with splinting the PIP joint in 30 degrees of flexion for 3 to 5 weeks.
PIP Joint Fracture Dislocation
Fracture dislocations occur when the extended finger is struck in such a way that longitudinal compression occurs along with hyperextension. The end result is a fracture through the volar lip of the middle phalanx and dorsal displacement of the middle phalanx and distal portion of the finger. This commonly occurs when the extended finger is struck by a ball.85
Patients with fracture dislocations are unable to flex the PIP joint and have swelling, pain, and deformity. On radiographs, there is dorsal subluxation of the middle phalanx with a fracture of the volar lip of the middle phalanx that may involve up to one-third of the articular surface.
Fracture dislocations may be reduced as per the routine method. If the fragment is large or unstable, open reduction and fixation are indicated. All of these injuries should be referred.
Metacarpophalangeal Joint Injuries
The MCP joints are condyloid joints that have, in addition to flexion and extension, as much as 30 degrees of lateral motion while the joint is extended. Because of the shape of this articulation, the joint is more stable in flexion when the collateral ligaments are stretched than in extension.
Collateral ligament and volar plate injuries of the MCP joint usually occur with hyperextension stresses applied to the MCP joint with the finger extended. The patient presents with massive ecchymosis and swelling of the joint. The radiograph is usually negative, but an avulsion fracture may be noted. The treatment of this injury is a gentle compressive dressing with light plaster reinforcement. These patients may require prolonged immobilization depending on the degree of injury and are referred for follow-up care. Nondisplaced fractures due to collateral ligament avulsion can be treated conservatively if the fragment involves less than 25% of the articular surface.19
Dislocations at the MCP joint are usually dorsal (Fig. 11–80). The complex anatomy of the MCP joint protects against dislocation, but also leads to a higher incidence of irreducible dislocations. There are two types of dorsal MCP joint dislocations: simple and complex.
Complex MCP joint dislocation of the second digit. This dislocation could not be reduced by closed methods. A. Note the subtle appearance of this dislocation. B. Radiograph.
Simple dorsal dislocations have a dramatic appearance clinically, with the MCP joint held in 60 to 90 degrees of hyperextension and the finger ulnar-deviated. The index finger is most commonly involved and the metacarpal head is prominent. This dislocation is usually reduced with closed techniques. Reduction is achieved by further hyperextension of the MCP joint, followed by dorsal pressure at the base of the proximal phalanx. Longitudinal traction may convert a simple dislocation into a complex one. After successful reduction, immobilize the MCP joint in 60 degrees of flexion.
Complex dorsal dislocations appear subtle clinically, with the proximal phalanx nearly parallel to the metacarpal. Other findings include a palpable metacarpal head on the volar surface with dimpling of the palmar skin. They are often impossible to reduce with closed techniques due to the interposition of the volar plate and the arrangement of ligaments and lumbrical muscles that actually tighten around the head of the metacarpal as traction is applied.
Subluxation at the MCP joint occurs when the proximal phalanx is locked in hyperextension and the articular surfaces are in partial contact. Reduction is performed by flexion of the digit after longitudinal traction using finger traps with 5 lb of weight applied to disengage the proximal phalanx.
Carpometacarpal Joint Injuries
These rare injuries are caused by forceful dorsiflexion combined with a longitudinal impact. Dorsal dislocation is most common (Figs. 11–81 and Figs. 11–82). A high-energy force is required and this injury is more common in boxers or after motorcycle crashes. Examination reveals considerable swelling in the dorsum of the hand that may cause the diagnosis to go undetected. When swelling is not as severe, the proximal metacarpals are palpated dorsally. Treatment includes reduction by traction with manipulation of the proximal metacarpal to its normal position (Video 11–6). The hand is immobilized (Appendix A–11) and the patient is referred. Unsuccessful or unstable closed reductions require open reduction and fixation. Complications include hand compartment syndrome, chronic stiffness, and nerve injury.
Video 11-6: Carpometacarpal dislocation reduction technique (this patient is shown in Figure 7-78).
Carpometacarpal dislocation of the fourth and fifth digits. A. Acutely, swelling obscures the diagnosis of this injury. B. The lateral radiograph demonstrates this dislocation best.
A rare posterior dislocation of all of the carpometacarpal joints.
Thumb Ligamentous Injuries and Dislocations
IP joint injuries of the thumb are handled similarly to distal IP joint injuries of the fingers. The most common injury is a dorsal dislocation with lateral dislocations being less frequent. Dorsal dislocations are often open. Reduction is usually simple after a median nerve block. The joint usually remains stable because the volar plate remains attached to the distal phalanx. The joint is immobilized for 3 weeks in slight flexion.
The MCP joint of the thumb is very mobile, and dislocations here are quite common (Fig. 11–83). The collateral ligaments are thick and provide good support for the joint. The volar plate contains two sesamoid bones that serve as the insertions for the flexor pollicis brevis (radial sesamoid) and the adductor pollicis (ulnar sesamoid). Because of the mobility of this joint, dislocations here are far more common than at the digits and are of two types, dorsal and lateral, each with an equal frequency.
MCP dislocation of the thumb. A. Clinical photo. B. Radiograph.
Dorsal dislocation of the thumb MCP joint occurs with extreme hyperextension or shearing forces, and disruption of the volar-supporting structures almost always occurs. Displacement varies from a subluxation of the phalanx to complete dislocation with the proximal phalanx resting over the metacarpal head. For the latter to occur, the volar plate and the collaterals must completely tear. When dislocation is associated with this degree of disruption of the supporting structures, reduction is usually easy and proceeds as follows: Flexion of the metacarpal relaxes the muscles and extension of the IP joint tightens the flexor tendon. Longitudinal traction is then applied until distraction occurs, and the MCP joint is flexed. After reduction, the digit is splinted for 3 weeks in flexion. If there is more than 40 degrees of lateral instability, surgical repair may be indicated. The amount of instability must always be assessed after reduction.
Lateral dislocations of the thumb MCP joint present with only local pain and swelling because they frequently have spontaneously reduced. To diagnose this injury, perform stress examinations of the ulnar and radial collateral ligaments of the thumb.
Trapezio-Metacarpal Joint Injuries
Dislocation of the trapezio-metacarpal joint of the thumb is an uncommon injury (Fig. 11–84). The mechanism is usually indirect, where a longitudinal force is directed along the axis of the thumb with the joint in flexion. Associated injuries include carpal and metacarpal fractures. Treatment is immediate reduction followed by immobilization in a short thumb spica splint (Appendix A–7) initially, and then a cast (Appendix A–6) for 6 weeks. Failure to maintain closed reduction or delayed presentation warrants fixation with percutaneous pinning.
Carpometacarpal dislocation of the thumb.
Ulnar collateral ligament rupture is 10 times more common than injury to the collateral ligament on the radial side. This injury can be very disabling, whereby the patient has a weak pinch and cannot resist an adduction stress. This injury is called gamekeeper’s thumb based on a description of ulnar collateral ligament laxity in Scottish gamekeepers due to their method of breaking the necks of wounded hares.86 It is also seen commonly in skiers (skier’s thumb) who have fallen where the ski pole abducts the thumb at the MCP joint. If this injury is missed, it may result in significant disability.
To diagnose ulnar collateral ligament injury, the examiner provides a radial-directed stress with the MCP joint in flexion (Fig. 11–85). Flexion allows the volar plate to relax and makes the test more sensitive. The degree of opening is compared with the normal side. Whether a partial or complete tear is suspected, the patient is placed in a thumb spica splint. A radiograph should be obtained, especially after acute injuries, to exclude an avulsion fracture at the base of the proximal phalanx, “gamekeeper’s fracture” (Fig. 11–86).
Examining for disruption of the ulnar collateral ligament of the thumb at the MCP joint.
Avulsion fracture in a patient with Gamekeeper’s thumb.
Definitive treatment depends on the degree of joint opening present. If the joint opens <20 degrees, no surgically correctable instability exists. The thumb should be splinted in the position of function for 3 weeks. If there is >20 degrees of instability, the patient is referred for repair of this ligament. Unfortunately, when >20 degrees of instability exists, splinting alone is ineffective in two-thirds of cases because the aponeurosis of the adductor pollicis becomes interposed between the ends of the disrupted ligament and the ligament cannot heal (Fig. 11–87).
If the aponeurosis of the adductor pollicis of the thumb becomes interspersed between the two ruptured ends of the ulnar collateral ligament, healing will not occur.
Although some surgeons believe that 40 degrees of opening can be treated without surgery, we recommend that all those with >20 degrees of opening at the joint be referred. Patients with gamekeeper’s thumb have been successfully treated with a special thumb splint designed to reduce motion simulating the injury.87 Surgical ligamentous reconstruction has been shown to be effective in achieving painless stability, even if delayed for years after the injury.88
Muscle soreness in the hand can occur with activity in an unconditioned patient. Treatment generally consists of rest, nonsteroidal anti-inflammatory agents, and future avoidance of similar activity. If the pain and soreness persist, other sources such as strains, sprains, stress fractures, or chronic exertional compartment syndrome are considered.89
Tendonitis is present when active and passive tension of the tendons accentuates the pain. The tenderness is usually well localized over the involved tendon. The condition may occur de novo, but usually presents after repetitive stress of the involved tendon. Swelling and erythema are infrequent with simple tendonitis. When the flexors of the digits are involved, the tenderness is most often over the MCP joint area. The treatment is local injection with a steroid, which affords excellent relief.
Tenosynovitis generally occurs without a recognized precipitating cause; however, a history of excessive stress on the tendon is often obtained. The most common site for this form of tendonitis is the extensor tendon sheath. On examination, the patient has a soft, nontender, diffuse subcutaneous swelling over the base of the hand confined to the area proximal to the extensor retinaculum. In some cases, one may get a dumbbell deformity with swelling seen on either side of the extensor retinaculum. The same condition may be seen with the flexors but is often not recognized due to the fat padding and the thickened skin of the palm. Commonly, the flexor tendons distal to the MCP joint are affected and this is easily recognized. The treatment for this form is rest and injection with steroids. Steroid injection usually affords prompt relief. A change in any precipitating activity is advisable.
Tendonitis involving the extensor tendons usually affects one of the six extensor tendon compartments. Tendonitis within the first compartment, containing the abductor pollicis longus and extensor pollicis brevis, is referred to as de Quervain tenosynovitis. Further discussion of this condition is provided in Chapter 8. Intersection syndrome is a more proximal tendonitis within the second extensor compartment commonly seen in rowers and weightlifters.90 Tendonitis within the third compartment affecting the extensor pollicis longus is rare, but when it does occur, it is usually at Lister tubercle. This may occur after a Colles fracture.91 Patients with tendonitis of the extensor digiti indicis (fourth) or minimi (fifth) present with pain at the wrist that can be reproduced by full passive flexion of the wrist. Patients who present with stenosing tenosynovitis of the extensor carpi ulnaris tendon (sixth) often require surgical release.
Flexor carpi ulnaris tendonitis may be bilateral and may require surgical excision of the pisiform. Flexor carpi radialis tendonitis causes local tenderness just proximal to the thenar eminence and pain with radial wrist deviation.90 Patients who have flexor tendonitis of the digits present with a stabbing or burning pain proximal to the carpal tunnel that mimics carpal tunnel syndrome.
This condition is due to perineural fibrosis that is caused by compression of the ulnar digital nerve of the thumb. Classically, this condition results due to adaptive changes in response to chronic insertion and compression of the thumb while grasping a bowling ball. Other activities, such as baseball, and occupational injuries have been implicated. An acute form of bowler’s thumb has also been described.92 Patients complain of tingling and hyperesthesia at the pulp of the thumb. Usually, a tender, palpable lump is present on the ulnar side of the thumb.
This condition, also known as stenosing tenosynovitis, is an idiopathic condition that occurs more commonly in middle-aged women. A secondary form occurs in patients with connective tissue disorders. Clinical findings include painful blocking of flexion and extension when a nodule on a flexor tendon catches on the tendon pulley at the MCP joint. At times, the patient complains only about the PIP joint, which is the site of referred pain from the proximal flexor pulley.
The ring and long fingers are the most commonly involved digits, but any digit may be affected, including the thumb. Active closing of the fist reproduces locking or snapping as the tendon slides through the pulley (Fig. 11–88 and Video 11–7). If the swelling is proximal to the pulley, then the digit can flex but not extend easily. However, if the swelling is distal to the pulley, then the digit can passively, but not actively, flex.
A. Trigger finger occurs when a fibrous thickening of the tendon does not allow it to slide through the pulley. B. Clinical photo of a finger locked in place due to trigger finger.
Two types of trigger finger occur: diffuse and nodular.93,94 The distinction is made based on the findings of physical examination. The nodular type is more common and responds to steroid injection with a success rate of 93%.93,95 For the diffuse type, the success rate of steroid injection is less impressive with only half of patients showing improvement.94
Radiographs should not be obtained because they do not change management.96 Treatment consists of massage, ice, nonsteroidal anti-inflammatory medications, and splinting. If the digit is locked, surgical intervention is often required. For lesser degrees of triggering, an injection of lidocaine (1 mL) and triamcinolone 40 mg/mL (0.5 mL) into the tendon sheath is recommended. Some authors prefer betamethasone because it is water-soluble and therefore less likely to cause tenosynovitis or leave a residue in the tendon sheath. The most common site of injection is over the palpable nodule on the palmar aspect of the palm in the region of the metacarpal head. After inserting a 25-gauge needle, the patient is asked to move the finger. Slight grating of the needle will be felt, but paradoxical motion of the needle and syringe suggests the needle is in the tendon and should be withdrawn.97 A palmar approach may also be used, but is felt to be more painful and therefore not recommended.93,98 Ultrasound-guided injection has proven to be very useful.99
Following the injection, extension of the finger is usually possible. The MCP joint should be splinted in extension with free motion of the PIP and DIP joints. This will allow the nodule to rest underneath the flexor tendon pulley. A removable splint is worn for 7 to 10 days (Appendix A–2).
Appropriate follow-up should be arranged as repeat injections and/or surgical release may be required.
This is a benign type of granulomatous vascular tumor that occurs frequently on the volar pulp or periungual area of a digit (Fig. 11–89). It is a solitary, pedunculated or sessile structure that bleeds easily with minimal trauma. It is minimally painful. Pyogenic granulomas often develop over a period of 1 to 3 months at a site where previous injury or foreign-body penetration has occurred. The size of the granuloma may be up to 2 cm in diameter, but is usually approximately 3 to 5 mm. The origin of pyogenic granulomas is unclear, although it is thought that they represent a disorder of angiogenesis.100
Removal of larger lesions is the treatment of choice. Various methods have been described, including silver nitrate application, electrocautery, avulsion, and surgical excision.101 One method for removal is described as follows:
A digital tourniquet is placed.
The lesion is excised flush with the surface of the skin.
The base of the lesion is cauterized with silver nitrate applicators.
Following removal, the patient is instructed to keep the lesion dry for 2 weeks. The lesion is allowed to heal by secondary intention.
This method had a 85% success rate in one study, but required more than one treatment in most cases.102 Recurrence is less likely with complete surgical removal, leaving a margin of normal tissue.100,103
Many things favor the development of infections in the hand, including retained foreign bodies, tight dressings around wounds, or congestive states following fractures. Staphylococcus aureus is isolated from 50% of all hand infections, followed by β-hemolytic Streptococcus, which accounts for 15% (Table 11–1). Other common organisms are Aerobacter aerogenes, Enterococcus, and Escherichia coli. Eikenella corrodens is an organism that is isolated from approximat ely one-third of human bite wounds.94 Pasteurella multocida, a facultative anaerobe, is present in the oral flora of approximately two-thirds of domestic cats and one-half of dogs.94 Infection with these organisms is usually rapid and associated with significant cellulitis and lymphangitis. Multiple organisms, however, are isolated from 70% of all hand infections. Rapid inflammation occurring within hours usually indicates that Streptococcus is the infecting organism in contrast with S. aureus, which usually takes several days to develop into an infection. The hallmarks of infection in the hand are warmth, erythema, and pain. Swelling and tenderness are other signs. Infections involving the tendons cause a limitation of motion and tenderness over the involved tendon.104
TABLE 11–1Common Pathogens in Hand Infections ||Download (.pdf) TABLE 11–1 Common Pathogens in Hand Infections
|Infection ||Most Likely Organism |
|Felon ||S. aureus, oral anaerobes |
|Flexor tenosynovitis ||S. aureus, Streptococci, gram-negative bacteria |
|Herpetic whitlow ||Herpes simplex 1 and 2 |
|Deep space infection ||S. aureus, anaerobes, gram-negative bacteria |
|Cellulitis ||Streptococcus spp. |
|IV drug user ||Gram-positive and -negative, anaerobes, S. aureus |
|Human bite ||S. aureus, Eikenella corrodens, anaerobes |
|Animal bite ||Pasteurella, gram-positive cocci, anaerobes |
The mainstay of treatment of any hand infection includes splinting and elevation as well as appropriate antibiotics. Antibiotic choices have changed recently with the surge in cases of community-acquired methicillin-resistant S. aureus (MRSA). Clindamycin or Bactrim (sulfamethoxazole and trimethoprim) are good initial options for patients who will likely be discharged. In more serious infections, vancomycin should be considered. Augmentin remains the antibiotic of choice for both human and animal bites. The clinician should be familiar with bacterial sensitivity patterns within their community and institution. Wound cultures should be obtained in any ill patient whenever fluid is available.
Elevation of the hand can be accomplished by using a stockinette (Fig. 11–90). This is an inexpensive dressing and works far better than a sling for elevating the hand. Tetanus prophylaxis must be administered when any wound is noted in patients not already immunized. Splinting should be in a position permitting maximal drainage for all hand infections (Appendix A–5).
A dressing used for elevation of the hand. The stockinette is applied along the entire upper extremity and cut at both ends to form a “Y.” The stockinette is fitted onto the upper extremity and the ends are then tied together.
Furuncles or carbuncles of the hand are common and occur over hair-bearing regions (Fig. 11–91A). These infections are usually caused by S. aureus and, when seen early, may be treated with rest, immobilization, elevation, and systemic antibiotics. Once the abscess is well localized, drainage occurs either spontaneously or through a small incision made over the point of maximal fluctuance with an 11-blade scalpel. Applying warm compresses facilitates drainage. If these infections are not treated adequately, they may lead to cellulitis of the hand.
A. Carbuncle on the dorsum of the hand. B. Cellulitis of the second digit.
Cellulitis can occur after an abrasion, puncture, or with any wound of the hand that has been inadequately immobilized or neglected (Fig. 11–91B). This infection is commonly found in intravenous drug users. Cellulitis may develop rapidly or slowly, depending on the offending agent. The hand should be immobilized to control congestion and the limb is elevated. In cases where the cellulitis is progressing rapidly over a period of hours, operative intervention must be considered because of the likelihood of a necrotizing soft-tissue infection. Necrotizing soft-tissue infections require immediate decompression and debridement as well as intravenous antibiotics. Patients with cellulitis of the hand that compromises function should be admitted.
A paronychia is an infection of the fold of the nail on the radial or ulnar side (Fig. 11–92A). The term eponychia is used when there is involvement of the basal fold of the nail (Fig. 11–92B). These may be associated with cellulitis when the infection extends proximally into the tissues around the nail fold. The typical patient comes into the ED with an abscess well localized around the nail fold or at the base of the nail. Most of these are due to staphylococcal infection and are treated by incision and drainage. An 11-blade scalpel is used and the “incision” is carried out by holding the blade against the nail and entering the abscess through the nail fold (Fig. 11–92C and Video 11–8). The nail fold is simply uplifted off the nail and drainage occurs. The patient should be advised to continue warm soaks. If cellulitis is present proximally, the patient is prescribed oral antibiotics.
Video 11-8: Drainage of the eponychia (from Figure 11-88B).
A. Paronychia. (Image used with permission from Kyle Jeray, MD.) B. Eponychia (compare to the normal digit). C. Drainage of a paronychia.
If this condition is not treated appropriately, a subungual abscess or felon may develop. A subungual abscess floats the fingernail off its bed and is drained by removing the base of the fingernail under digital block anesthesia. The distal nail plate is not usually excised. A tiny loose pack of fine meshed gauze is inserted to separate the matrix from the eponychial fold for a few days.
A felon is a subcutaneous abscess of the pulp space of the distal fingertip (Fig. 11–93A). This infection resides within the vertically oriented fibrous septa that originate on the periosteum and insert on the skin.105 Left untreated, this infection may spread, infecting the distal phalanx or the flexor tendon sheath. Clinically, there is a rapid onset of throbbing pain and swelling distal to the DIP joint.
A. Felon. B. Drainage via the longitudinal incision. C. Drainage via a high lateral incision.
Early infection is treated by elevation, oral antibiotics, and warm soaks alone, although most patients present later and require drainage. Incision and drainage should be at the point of maximum tenderness in these infections. There is some controversy regarding the best incision to treat a felon.105 A longitudinal midline incision, which spares the flexion crease (Fig. 11–93B) avoids injury to the vessels and the digital nerves. The scalpel is used to penetrate the dermis only, and a mosquito hemostat is used to gently dissect the soft tissues until the abscess cavity is drained. Controversy remains about the painful scar in the pulp of the finger. A unilateral longitudinal incision (“high lateral”) is also acceptable if fluctuance is noted laterally, but care must be taken to avoid injury to the terminal branches of the digital nerves.105,106 A rule of thumb is to bend the DIP joint and the upper extent of the flexion fold defines how high the incision should be. Lower than that puts the neurovascular structures at risk. Other incisions for this common problem have been advocated (fish-mouth, through-and-through, transverse palmar, hockey-stick), all of which invoke necrosis and ischemia, lead to anesthesia of the tip of the digit, and produce a more painful scar than the midline incision.
Following drainage, the finger is dressed, splinted, and the patient is started on a course of antibiotics for 10 days. The patient is instructed to elevate the finger for 48 hours. At this time, the dressing is removed, the wound reexamined, and twice a day dressing changes with saline soaks are begun. The wound is allowed to heal secondarily.
There are five potential spaces located deep inside the hand that represent potential sites of infection (Fig. 11–94). These infections, referred to as deep subfascial space infections, represent 5% to 15% of all hand infections. The emergency physician should distinguish between infections of the web space, midpalmar space, dorsal aponeurotic space, thenar space, and hypothenar space.
Cross-sectional anatomy of the hand, demonstrating the thenar, midpalmar, hypothenar, and dorsal subaponeurotic spaces.
Interdigital web space infections present with painful swelling of the web space and distal palmar regions (Fig. 11–95A). Pain and swelling is noted on both the dorsal or volar surfaces, but is usually more significant on the dorsum. Depending on the degree of swelling, the fingers may be abducted. These infections are also known as a collar button abscess and are most often caused by a puncture wound to the web space.
A. Web space (collar button) abscess (Image used with permission from Kyle Jeray, MD.) B. Thenar space infection.
Treatment includes drainage by a dorsal incision between the fingers. The direction of the incision is controversial, however, a longitudinal incision at the web space has been advocated to avoid contracture107 (Fig. 11–96). A volar incision may also be necessary. This infection often leads to stiffness at the MCP joint, unless treated early with incision and drainage, elevation, and antibiotics. Hand consultation for this infection is appropriate.
A web space infection should be drained by a longitudinal dorsal incision between the fingers.
Midpalmar Space Infection
Infection here is secondary to (1) extension of an infection from the adjacent flexor sheaths or (2) a puncture wound of the palm of the hand. The palmar fascia is under great tension and maximal edema forms over the dorsum of the hand. However, the point of maximal tenderness is the midpalm. The concavity of the palm is lost. This abscess requires immediate drainage in the operating room.
Dorsal Subaponeurotic Space Infection
The dorsum of the hand is covered by loose, redundant skin that permits significant edema to accumulate from any of the infections occurring elsewhere in the hand. This dorsal edema must be differentiated from infections along the dorsum of the hand, namely, the subaponeurotic space that is contained by extensor tendons and the metacarpals. Infection on the dorsum of the hand due to a subcutaneous abscess or a subaponeurotic space infection is accompanied by tenderness, which is not present with simple dorsal edema. These infections usually require drainage through multiple incisions and require hand consultation.108
This infection is diagnosed by noting considerable thenar and first web space swelling and tenderness (Fig. 11–95B). The patient will abduct the thumb because the volume within the thenar space is greatest in this position. The examiner will also elicit pain with passive adduction or opposition. These infections usually require drainage through multiple incisions and require hand consultation.108
Hypothenar Space Infection
This infection is extremely rare. Swelling and tenderness is noted at the hypothenar eminence.107 Treatment involves a longitudinal incision on the ulnar aspect of the palm and is best performed by a consulting hand surgeon.
The flexor tendons are covered by a closed tendon sheath and bursae that may become infected by puncture wounds or lacerations (Fig. 11–97). The joint creases, where the tendon and its surrounding sheath are in close proximity to the skin, are particularly susceptible. S. aureus and Streptococcus are the most common infecting agents. Disseminated gonorrhea should be considered in sexually active patients without a history of trauma. Because there is no obstruction to spread the infection, usually the entire tendon sheath becomes involved.
Flexor tendon sheaths of the hand. Note that the flexor sheath of the flexor pollicis longus communicates with the radial bursa and the sheath of the little finger communicates with the ulnar bursa.
Kanavel described four cardinal signs of acute flexor tenosynovitis that are usually present (Fig. 11–98)108,109:
Flexor tenosynovitis of the second digit. A. Symmetric enlargement of the digit. B. Flexed resting position.
Excessive tenderness over the course of the tendon sheath, limited to the sheath (Video 11–9)
Symmetric enlargement of the whole finger
Excruciating pain on passively extending the finger, along the entire sheath
Flexed resting position of the finger
Video 11-9: Flexor tenosynovitis.
Tenderness is present along the course of the entire tendon sheath as it extends into the palm.
Passive extension of the finger stretches the involved synovial sac and results in pain. This is best accomplished by avoiding palpation of the finger directly and extending the finger by lifting up on the nail alone (Fig. 11–99).
Testing for acute suppurative flexor tenosynovitis. Uplifting the nail of the involved digit without palpating the tendon causes exquisite pain.
These patients are splinted and the hand is elevated. Intravenous antibiotics are administered in the ED. Consultation with a hand surgeon is obtained and the patient is admitted for intravenous antibiotics alone if the infection is early (within 24 hours). If the infection is well established or no improvement is seen with antibiotics, surgical treatment is necessary. Limited incisions and catheter irrigation alone are becoming more common as a means to avoid more invasive surgery.108 If improperly treated, these infections may result in chronic tendon scarring or the development of a deep space infection of the hand.2
A human bite wound is a very serious injury, especially when it occurs over poorly vascularized tissues such as the ligaments, joints, or tendons in the hand. The overall incidence of infection for human bites is 10%.110 Although a variety of organisms are involved, the prime pathogens are anaerobic Streptococcus and S. aureus.
Injuries to the hand, especially the MCP joint, following a fist fight, are typically referred to as “closed (clenched) fist” or “fight bite” injuries. Fight bites are self-sealing and prone to infection of the soft tissues, joint space, and the tendon sheath. The additional challenge to the emergency physician is that the wound is small (3–5 mm) and may appear quite innocuous (Fig. 11–100).108,110 These wounds are treated with the utmost expediency and are never closed.
Infected fight bite injury over the middle-finger MCP joint.
Radiographs are recommended in an effort to search for associated fractures, tooth fragments, or signs of osteomyelitis. Proper treatment of infected fight bite injuries involves debridement, thorough irrigation, immobilization (Appendix A–5), elevation, and systemic antibiotics. Antibiotics include a β-lactamase inhibitor (ampicillinsulbactam) or a second-generation cephalosporin (cefoxitin). Admission for hospitalization and operative debridement are indicated if the wound is infected.
If the wound is not infected at the time of presentation, careful exploration of the wound in the ED is indicated. The wound must be carefully extended and explored to exclude tendon injury or joint involvement (Video 11–10). If these injuries are excluded, the patient may be managed conservatively on an outpatient basis.2,110 Irrigation is performed and the wound is allowed to heal by secondary intention. Prophylactic antibiotics are administered and follow-up arranged in the next 1 to 2 days.
Video 11-10: Extension of a fight bite to examine the extent of injury and irrigate the wound.
Approximately half of all persons in the United States are bit by an animal at some point in their lifetime (Fig. 11–101).103 Dog bites are the most common animal-inflicted bite, accounting for 80% of the total and up to 1.5% of all ED visits.111,112 Approximately 15% to 20% of dog bite wounds become infected.113 Infection is more likely with deeper wounds, crush wounds, puncture wounds, and wounds on the hand. P. multocida, S. aureus, and anaerobic organisms account for most cases. Augmentin is the antibiotic of choice and is administered prophylactically for 3 to 7 days in high-risk wounds and for 2 weeks if cellulitis is present. Tetanus prophylaxis is administered as with any wound. Hospitalization is recommended in systemically ill patients, those with rapidly spreading cellulitis, or involvement of bone, joint, or tendon.
Infected finger due to an animal bite.
Domestic cat bites account for only 5% of all animal bites, but 50% will become infected due to cats’ thin, sharp teeth that drive bacteria deep into tissues.108,111,114 Irrigation and debridement is recommended and the wound is not closed primarily. The most common organism in cat bites is P. multocida, but Staphylococcus, Streptococcus, and anaerobes are also seen. Augmentin is the antibiotic most commonly used for both prophylaxis and infection.
Rabies vaccination or animal quarantine for rabies evaluation should also be considered in an unprovoked attack.