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292 SECTION 6: Wound Management Motor Function Evaluate active motion and resistance to passive movement. Patients with a painful injury may be unwilling to move the affected extremity. After checking sensory function, local anesthesia may be required to obtain an adequate motor exam. The belief that a local anesthetic with epinephrine should not be used for digital nerve blocks is without evidence, and clinical observation studies have found agents containing epinephrine safe for digital nerve blocks. 1,2 The most distal pure motor function of each major nerve should be tested against resistance (Table 43-1). Individually assess each tendon within, and adjacent to, the injured area. For injuries to the hand and fingers, individually examine the extensor digitorum, flexor digitorum profundus, and the flexor digito rum superficialis of each digit. The flexor digitorum superficialis, which splits and inserts at the proximal interphalangeal joint, can be examined by holding all other digits in extension and flexing the proximal inter phalangeal joint against resistance. The flexor digitorum profundus, which runs below the flexor digitorum superficialis past the split to attach at the distal interphalangeal joint, can be examined by holding the proximal interphalangeal joint in extension and flexing the distal interphalangeal joint against resistance. The extensor digitorum can be assessed by sequentially flexing the digit at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints and having the patient extend the digit. Extension should be performed first against gravity and then against resistance applied by the examiner. Weak, limited, or painful movement suggests partial involvement of a tendon. Abnormality in motor nerve or tendon function testing warrants a more in-depth evaluation, including visual exploration of the wound after anesthesia. Sensory Function Assess pain and touch sensation in the median, ulnar, and radial nerve distributions ( Table 43-2 and Figure 43-1). For injuries distal to the midpalm, assess the digital nerves by static twopoint discrimination, testing longitudinally along the ulnar and radial aspect of the volar pad of the potentially involved digits. Static two-point discrimination is evaluated by using ECG calipers or a paper clip bent into a “V” shape with the two ends separated by approximately 5 to 6 mm. During testing, the two points should not cross the midline, and each stimulus should be timed 3 to 4 seconds apart. Normal two-point discrimination is defined as <6 mm; good is 6 to 10 mm, fair is 11 to 15 mm, and poor is >15 mm. Two-point spatial acuity of touch dimin ishes with age. Y oung (18 to 33 years) patients have a mean two-point acuity of 2 mm, whereas elderly (>66 years old) patients have a mean acuity of 5 mm. 3 The two most important areas to maintain sensation are the ulnar side of the distal thumb and the radial side of the index volar pad to preserve pinch sensation. Vascular Supply Intact radial and ulnar pulses and capillary refill are usually adequate to exclude significant vascular injury. However, an arterial injury proximal to the wrist may not be obvious as a result of collateral circulation. Perform the Allen test to better assess the integrity of the radial and ulnar arteries.

ular Supply Intact radial and ulnar pulses and capillary refill are usually adequate to exclude significant vascular injury. However, an arterial injury proximal to the wrist may not be obvious as a result of collateral circulation. Perform the Allen test to better assess the integrity of the radial and ulnar arteries. The test is performed by first instructing DISPOSITION AND FOLLOW-UP Where possible, the wound should be dressed with either an antibiotic ointment or nonadherent dressing material to maintain moisture and encourage wound healing. 54-56 Patients should be discharged with routine wound-care instructions (see Chapter 47, “Postrepair Wound Care”) and, if the injury resulted from a major blunt impact, closed head injury precautions. Remove scalp sutures or staples in 14 days, and remove nonabsorbable percutaneous sutures in the forehead, external ear, or lips in 5 days. Underlying absorbable sutures will maintain structural integrity for wounds that were under tension. Percutaneous nonabsorbable sutures placed in the eyelid, nose, or face should be removed in 3 to 5 days. A thin layer of ophthalmic antibiotic ointment may be applied in place of a dressing; do not apply antibiotic ointment intended for routine use elsewhere around the eye. Remove intranasal packing in 1 to 2 days. Auricular pressure dressings should be left undisturbed for 24 hours and then removed for inspection of the wound site. If the wound is healing without infection or hematoma, replacement of the pressure dressing is not necessary. Patients with intraoral lacerations should practice good oral hygiene and rinse their mouth several times a day. There is no evidence to sup port the use of prophylactic antibiotics for intraoral lacerations and through-and-through facial wounds; their use is a matter of physician preference. 57,58 REFERENCES The complete reference list is available online at www.TintinalliEM.com. Arm, Forearm, and Hand Lacerations Moira Davenport GENERAL MANAGEMENT PRINCIPLES Specific concerns relative to wounds and lacerations of the arm and hand include potential injury to the arteries, nerves, and tendons that lie close to the skin and the impact of these injuries on the use of the hands in daily and occupational life. Injuries may be classified as either isolated or combinations of closed crush, simple lacerations, open crush, partial amputation, and complete amputation.  HISTORY AND EXAMINATION Specific considerations in the history include patient age, occupation, mechanism of injury, and hand dominance. Age is important because the potential for bony injury increases with decreasing bone density, and the likelihood for healing and functional recovery decreases with age due to loss of elasticity. Mechanism of injury identifies wounds that are more prone to infection or injury to deeper structures. Note the time from injury to repair; there is no distinct threshold for infection from time of injury to closure, but wounds sutured >12 hours after injury could be more prone to infection (see Chapter 39, “Wound Evaluation”). (See Videos: Hand Exam and Digital Nerve Block.) Inspection Observe the position and stance of the arm, hand, and digits. Identify exposed tendon or bone and note the location of the wound relative to major arteries, nerves, and tendons. Inspect the wound care fully for possible foreign body, debris, or other visible contaminants. Note significant soft tissue avulsion or loss of length of the injured part, as these findings may be indications for operative repair. Remove rings from the affected arm.

ound relative to major arteries, nerves, and tendons. Inspect the wound care fully for possible foreign body, debris, or other visible contaminants. Note significant soft tissue avulsion or loss of length of the injured part, as these findings may be indications for operative repair. Remove rings from the affected arm. (See Video: Ring Removal.) CHAPTER TABLE 43-1 Motor Testing of the Peripheral Nerves of the Upper Extremity Nerve Motor Exam Radial Dorsiflexion of wrist Median Thumb abduction away from the palm Thumb interphalangeal joint flexion Ulnar Adduction/abduction of digits TABLE 43-2 Sensory Testing of Peripheral Nerves in the Upper Extremity Sensory Nerve Area of Test Radial First dorsal web space Median Volar tip of index finger Ulnar Volar tip of little finger Tintinalli_Sec06_p0267-0328.indd 292 8/2/19 7:15 PM

lm Thumb interphalangeal joint flexion Ulnar Adduction/abduction of digits TABLE 43-2 Sensory Testing of Peripheral Nerves in the Upper Extremity Sensory Nerve Area of Test Radial First dorsal web space Median Volar tip of index finger Ulnar Volar tip of little finger Tintinalli_Sec06_p0267-0328.indd 292 8/2/19 7:15 PM CHAPTER 43: Arm, Forearm, and Hand Lacerations 293 the patient to make a fist as tightly as possible. Then, apply digital pres sure to both the radial and ulnar artery at the volar aspect of the wrist. Next, while maintaining compression of the radial and ulnar artery, have the patient open the hand—a blanched palm indicates that arterial inflow is occluded. Now release the radial artery and note the time for the hand to return to normal color. Repeat the entire process, this time releasing the ulnar artery. If the patient cannot make a fist, occlusion of both arteries will still blanch the hand, but the color change will not be as evident or pronounced. Refill times >3 seconds raise suspicion for a significant vascular injury. A Doppler probe is useful to detect a diminished pulse, detect flow in digital arteries, and calculate an arterial pressure index. The arterial pressure index is the ratio of the systolic blood pressure between the injured and the uninjured side. It is useful to assess the vascular integ rity of an injured arm or leg. To obtain the index, place a blood pressure cuff proximal to the ankle or wrist of the injured limb and distal to the wound. Then use a Doppler probe to determine the systolic pressure at the radial or ulnar artery. In the absence of a diminished pulse or an arterial pressure index ratio <1.0, the likelihood of a clinically significant arterial injury is <5%. 4,5 Lack of obvious arterial bleeding does not rule out arterial injury because cleanly transected arteries may contract and prevent obvious bleeding. Abnormal findings warrant consultation with a vascular surgeon as well as with a hand surgeon.  IMAGING Obtain radiographs with anteroposterior, oblique, and lateral views if bony injuries, foreign bodies, or joint penetration are suspected. Addi tional oblique views of the hand and digits are useful to visualize small areas with overlapping bones. For isolated finger injuries, dedicated anteroposterior and lateral radiographs of the involved digit(s) are preferred, as the detail on hand films alone is often not adequate for complete visualization of small, subtle fractures. Plain radiography visualizes radiopaque objects as small as 1 mm. When there is suspicion for a radiolucent retained foreign body, especially wood, other imaging modalities (US, CT, or MRI) may be necessary (see Chapter 45, “Soft Tissue Foreign Bodies”). US is gaining popularity as a means to evaluate for fracture, foreign body, and tendon/ligament integrity. 6 Tendon function can be evaluated using US and the water bath technique. (See Video: Waterbath for Finger Exam.)  WOUND VISUALIZATION AND TOURNIQUET APPLICATION Because wounds and the affected structures are often small, patient positioning, bright lighting, and a bloodless field are necessary for wound evaluation. Local anesthesia or nerve blocks are needed to adequately examine the wound. Test sensation and motor function prior to anesthesia if at all possible. (See Video: Forearm Nerve Blocks.) For some injuries, a bloodless field may require a proximal tourniquet to temporarily halt arterial inflow and allow adequate visualization of Ulnar N Radial N Median N FIGURE 43-1. Sensory innervation to the hand. N = nerve. the injury.7 Penrose (rubber) drains are typically used to tourniquet an injured finger, and pneumatic tourniquets placed around the arm are used with forearm and wrist injuries. To tourniquet a digital injury, place a 1-in.

alization of Ulnar N Radial N Median N FIGURE 43-1. Sensory innervation to the hand. N = nerve. the injury.7 Penrose (rubber) drains are typically used to tourniquet an injured finger, and pneumatic tourniquets placed around the arm are used with forearm and wrist injuries. To tourniquet a digital injury, place a 1-in. Penrose drain around the base of the finger, stretch the drain away from the hand, and secure the drain with a clamp or hemostat. Excessively high pressures and tourniquet times >15 to 20 minutes can cause neurovascular damage and may be avoided by limiting the stretch of the drain to no more than 50% of the original length. For more proximal injuries, especially those with brisk arterial bleeding, an inflated manual blood pressure cuff is used. Esmarch’s technique is used to exsanguinate the limb and prevent backflow bleeding. Elevate the injured extremity and apply an elastic bandage starting distally and wrapping proximally to the area where the cuff will be applied. The cuff is applied around the upper arm and inflated to pressures above the systolic blood pressure of the patient, but not to exceed 250 mm Hg (33 kPa). The cuff tubing is clamped with a hemostat instead of clos ing the air release valve to prevent slow air leakage. The maximum cuff inflation time is limited to 30 minutes to avoid ischemic damage to the distal muscles and nerves. Once adequate visualization is obtained, examine the area for foreign bodies and tendon and joint capsule injuries. Examine the arm and hand in a variety of positions, including the position of injury and a full, passive range of motion, to avoid missing injuries that may move out of the field of view when the extremity is examined in a neutral position. Examine lacerations near a joint carefully to identify violation of the joint capsule. If the location and depth of the injury raise the question of extension into the joint capsule, joint injection for a saline load test can be done, although there is minimal evidence for its sensitivity in upper extremity joints other than the elbow. 9 Inject sufficient amounts of saline to adequately stress the capsule; false-negative results may be obtained if too little fluid is injected. Fluid dripping from the joint indicates an open joint capsule and requires specialty consul tation. For small joints or questionable exams, a few drops of sterile fluorescein for IV use (Ak-Fluor ® ) may be added to the injected saline and the joint examined with a Wood’s lamp for evidence of fluorescent effluent. There is no advantage of adding methylene blue to the injected saline, and it may affect operative management by staining the intra-articular surfaces.  WOUND DRESSING AND POSTREPAIR CARE After the injury is repaired, apply antibiotic ointment to the repaired incision/sutures and cover the wound with a nonadherent dressing. Wrap the area loosely with a soft dressing to allow for adequate circulation. Leave a small portion of the fingernail or volar pad visible to allow serial assessment of capillary refill in patients with digital injuries. Tubular gauze over a finger wound should not be applied in more than two layers or twisted between layers to prevent a tight bandage producing ischemic damage to the digit. 10,11 Certain injuries, especially large lacerations in close proximity to a joint and those with tendon involvement, may be splinted for protection and limitation of pain. Provide adequate analgesia and remind the patient to keep the injured extremity elevated above the level of the heart for the first 24 hours to reduce edema. A follow-up wound check is recommended within 48 to 72 hours. Sutures are usually removed 8 to 10 days after the injury. Provide tetanus immunization or booster as needed.

dequate analgesia and remind the patient to keep the injured extremity elevated above the level of the heart for the first 24 hours to reduce edema. A follow-up wound check is recommended within 48 to 72 hours. Sutures are usually removed 8 to 10 days after the injury. Provide tetanus immunization or booster as needed. Infection of simple hand lacerations is low, between 1% and 5%. 12,13 Prophylactic antibiotics are not needed for uncomplicated hand lacerations. Uncomplicated hand lacerations are those that: (1) are not caused by a human or animal bite; (2) are not complicated by a fracture through bone or a joint; (3) do not involve tendons, bones, large ves sels, or nerves; or (4) have no severe soft tissue damage or maceration. Antibiotics are generally given for mammalian bite wounds (see Chapter 46, “Puncture Wounds and Bites”) and are considered for injuries >12 hours old, contaminated wounds, or injuries with exposed bone. 15 There is a lack of evidence regarding the use of antibiotics following simple hand lacerations in patients with concurrent medical problems that may affect wound healing (i.e., diabetes, renal or peripheral vascular disease, immunocompromise). Antibiotics should be chosen to cover suspected contaminants and pathogens and should be given Tintinalli_Sec06_p0267-0328.indd 293 8/2/19 7:15 PM

simple hand lacerations in patients with concurrent medical problems that may affect wound healing (i.e., diabetes, renal or peripheral vascular disease, immunocompromise). Antibiotics should be chosen to cover suspected contaminants and pathogens and should be given Tintinalli_Sec06_p0267-0328.indd 293 8/2/19 7:15 PM 294 SECTION 6: Wound Management early in the ED by a route that quickly achieves high blood and tissue concentrations. Indications for admission to the hospital include injuries that require repair in the operating room, those that require a course of IV antibiot ics for infection, or the presence of social issues such as abuse cases, homelessness, or other factors affecting the patient’s ability to follow basic aftercare instructions.  INJURIES IN CHILDREN Because of the presence of an open epiphysis in children, a fracture can be difficult to identify using plain radiographs. It is often necessary to obtain radiographs of the unaffected side for comparison. Procedural sedation may be required if the child is unable to tolerate the procedure after local anesthesia alone. The continuous high activity level of chil dren makes keeping dressings intact a problem, rendering routine hand dressings and splints ineffective. If the dressing and immobilization are essential to wound healing, the child can be placed in a long-arm splint or bi-valved cast. UPPER ARM AND ELBOW LACERATIONS Lacerations of the upper arm and elbow account for about 9% and 7%, respectively, of upper extremity lacerations presenting to the ED. 16 The major issues with lacerations in these areas are potential for (1) arte rial laceration, (2) nerve laceration, and (3) elbow joint penetration. After excluding such injuries, wounds in this region can be closed with absorbable monofilament (e.g., 4-0 polydioxanone) for deep layer clo sure and 4-0 nylon or surgical staples for skin closure. DORSAL FOREARM, WRIST, AND HAND LACERATIONS The forearm has six extensor compartments located dorsally, all of which are innervated by the radial nerve ( Table 43-3). The dorsal skin on the forearm and hand is thin and lacks underly ing tissue, which allows avulsions to easily occur, making wound edge approximation sometimes difficult. For most lacerations, simple 5-0 nonabsorbable percutaneous sutures should be adequate for closure. To provide better cosmesis for injuries to the dorsum of the hand, con sider subcuticular stitches with 5-0 absorbable material (see Figure 41-6). Closure of the fascial defect with 4-0 absorbable sutures for deep wounds that penetrate through the muscle fascia and lacerate the muscle belly is generally recommended. However, deep sutures increase the potential for infection in a contaminated wound. CLENCHED FIST INJURIES Patients with lacerations to the dorsum of the hand should be ques tioned about the possibility of a clenched fist injury, “fight bite, ” or tooth-knuckle injury, wounds created by the patient throwing a punch, impacting the front teeth of the intended target, and producing a small laceration (3 to 5 mm) over the dorsal metacarpophalangeal joint. Extension of the affected digit after the fight deeply inoculates oral bac teria into the wound with a high risk for complications. 18 Staphylococcus aureus is the most common bacterial species isolated from human bite wounds, followed by Streptococcus spp., Corynebacterium spp., and Eikenella corrodens. In clenched fist injury infections, polymicrobial involvement is the rule. 19 Human bites can also transmit herpes, actinomycosis, syphilis, tetanus, and hepatitis B and C. Bites are not the only way to inoculate the hand with human oral flora; significant hand and finger infections have been reported after toothpick injuries.

hed fist injury infections, polymicrobial involvement is the rule. 19 Human bites can also transmit herpes, actinomycosis, syphilis, tetanus, and hepatitis B and C. Bites are not the only way to inoculate the hand with human oral flora; significant hand and finger infections have been reported after toothpick injuries. Patients sustaining such puncture wounds should receive antibiotics to protect against the above-mentioned bacteria. Obtain radiographs on clenched fist injuries to evaluate for embedded teeth, air in the joint/soft tissues, and fractures. Patients who delay evaluation and develop obvious infection require exploration, open irrigation, and debridement in the operating room followed by admission for IV antibiotics and elevation. Patients presenting soon after the injury and without evident infection can undergo evaluation, exploration, and irrigation in the ED with appropriate equipment and physician expertise. It is important to visualize the full extent of the wound, evaluate the hand through full range of motion, and exclude injury to the extensor tendon and joint capsule. If no injury to these structures is seen, the wound should be copiously irrigated. Most practitioners do not close fresh closed fist injury wounds; instead, the wound is covered with a nonadherent dressing and allowed to heal by secondary intention or undergo delayed primary closure in 4 to 5 days or revision at a later date. Fresh, uninfected wounds may be closed, although that decision is best made by a hand surgery specialist who has adequately explored the wound. Splint the hand in a position of function (Figure 43-2). A 3- to 5-day course of prophylactic antibiotics should be prescribed, usually amoxicillin-clavulanic acid. Give the first antibiotic dose in the ED. Instruct the patient to elevate the extremity and return for reevaluation in 24 to 48 hours. Consult a hand surgeon if there is already evidence of infection or joint/tendon involvement, and consider an initial dose of IV antibiotics, typically ampicillin-sulbactam or cefoxitin. EXTENSOR TENDON LACERATIONS The dorsal skin of the hand is thin and freely mobile with the extensor tendons located very superficially. A careful examination through a full range of motion at the site of injury in a neutral position and in the position of injury is necessary to avoid missing a tendon injury. Consult 5° 10° 30° 25° FIGURE 43-2. Wrist and hand position when splinted in “position of function.” The wrist is extended 25 degrees so that the thumb metacarpal is in alignment with the forearm. The thumb is abducted away from the palm. Metacarpophalangeal joints are flexed to 30 degrees. Proximal interphalangeal joints are flexed to 10 degrees. Distal interphalangeal joints are flexed to 5 degrees. TABLE 43-3 Extensor Compartments in the Forearm Compartment Muscle Function First compartment Abductor pollicis longus Extensor pollicis brevis Abducts and extends thumb Extends thumb at MCP joint Second compartment Extensor carpi radialis longus Extensor carpi radialis brevis Extends and radially deviates wrist Extends and radially deviates wrist Third compartment Extensor pollicis longus Extends thumb at interphalangeal joint Fourth compartment Extensor digitorum communis Extensor indicis proprius Splits into four tendons at level of the wrist; extends index, long, ring, and little digits Extends index finger Fifth compartment Extensor digiti minimi Extends little finger at MCP joint Sixth compartment Extensor carpi ulnaris Extends and radially deviates wrist Abbreviation: MCP = metacarpophalangeal. Tintinalli_Sec06_p0267-0328.indd 294 8/2/19 7:15 PM

e wrist; extends index, long, ring, and little digits Extends index finger Fifth compartment Extensor digiti minimi Extends little finger at MCP joint Sixth compartment Extensor carpi ulnaris Extends and radially deviates wrist Abbreviation: MCP = metacarpophalangeal. Tintinalli_Sec06_p0267-0328.indd 294 8/2/19 7:15 PM CHAPTER 43: Arm, Forearm, and Hand Lacerations 295 a hand surgeon for wounds with gross contamination, that are large, or that result from crush injury; these need emergent exploration in the operating room. 21 For most other extensor tendon injuries of the digits, irrigate the wound, close the skin, splint with wrist and digit in exten sion, and refer the patient to a hand specialist for repair later. Extensor tendon injuries between the distal wrist and metacarpophalangeal joints can be repaired in the ED. It is recommended to consult the hand surgeon for treatment preferences and ensure continuity of care. Small partial extensor tendon injuries (<50% transected) should be repaired with absorbable synthetic material. Larger partial tendon inju ries (>50% transected) and complete extensor tendon lacerations should be sutured with 4-0 (5-0 for smaller tendons) colorless nonabsorbable material, such as polypropylene or nylon, and the skin closed with 5-0 nonabsorbable suture material. A figure-of-eight stitch with the knot placed at the edge of the tendon is recommended to repair lacerated extensors (Figure 43-3). After repair of the tendon and overlying skin, splint the hand or digit in a position of function with instructions to maintain elevation of the extremity for 24 hours (Figure 43-2). Follow-up with a hand surgeon is recommended. Complications can be seen with disrupted extensor mechanisms. The mallet finger deformity (inability to extend the distal interphalangeal joint, resulting in the joint being held in flexion) and swan neck deformity (hyperextension of the proximal interphalangeal joint resulting from unrepaired mallet finger deformity) are caused by the complete disruption of the terminal extensor mechanism and subsequent proximal and dorsal displacement of the lateral bands ( Figures 43-4A and 43-4B). A boutonniere deformity (hyperflexion of the proximal inter phalangeal joint with hyperextension of the distal interphalangeal joint) is usually a delayed complication after injury to the proximal inter phalangeal joint. The central slip of the extensor tendon is disrupted, allowing the lateral bands to move volarly and operate as flexors at the proximal interphalangeal joint while still producing extension at the distal interphalangeal joint (Figure 43-4C ). If these injuries are open, operative repair is required. Closed injuries may be treated by splint ing the digit in extension (distal interphalangeal joint for mallet finger and both proximal interphalangeal and distal interphalangeal joints for boutonniere deformity) for up to 6 weeks or until operative repair. 22,23 Patients should be referred to a hand surgeon for follow-up. VOLAR FOREARM, WRIST, AND HAND LACERATIONS Patients with volar wrist lacerations should be questioned about suicidal attempts, and potentially suicidal patients require psychiatric evalua tion after wound repair. 24 There are 12 flexor tendons innervated by the median and ulnar nerves located on the volar surface of the forearm that cross the wrist (Table 43-4). Injuries in the elbow region may affect the radial and ulnar nerves, which run in close proximity to the lateral and medial epicondyles, respectively. The radial nerve emanates from the spiral groove in the FIGURE 43-3. Extensor tendon laceration repair with a figure-of-eight stitch. A Mallet finger B Swan neck C Boutonniere FIGURE 43-4. A. Mallet finger. B. Swan neck finger. C. Boutonniere deformity.

ose proximity to the lateral and medial epicondyles, respectively. The radial nerve emanates from the spiral groove in the FIGURE 43-3. Extensor tendon laceration repair with a figure-of-eight stitch. A Mallet finger B Swan neck C Boutonniere FIGURE 43-4. A. Mallet finger. B. Swan neck finger. C. Boutonniere deformity. Tintinalli_Sec06_p0267-0328.indd 295 8/2/19 7:15 PM

ose proximity to the lateral and medial epicondyles, respectively. The radial nerve emanates from the spiral groove in the FIGURE 43-3. Extensor tendon laceration repair with a figure-of-eight stitch. A Mallet finger B Swan neck C Boutonniere FIGURE 43-4. A. Mallet finger. B. Swan neck finger. C. Boutonniere deformity. Tintinalli_Sec06_p0267-0328.indd 295 8/2/19 7:15 PM 296 SECTION 6: Wound Management humerus approximately 10 cm proximal to the lateral epicondyle. The ulnar nerve travels behind the medial epicondyle as it runs between the two heads of the flexor carpi ulnaris into the forearm. The median nerve in the elbow region is more protected, as it runs in close proxim ity to the brachial artery and crosses anteriorly to the ulnar artery at the origin of the anterior interosseous nerve in the forearm. Although injuries to these nerves are more common with fractures and dislocations, simple soft tissue injuries at the elbow may result in nerve damage due to the superficial location and lack of overlying protective soft tissue in this area. For most simple lacerations to the volar surface of the forearm and wrist, 4-0 or 5-0 nonabsorbable monofilament percutaneous sutures, such as nylon or polypropylene, should be used. For gaping injuries or injuries under high stress, a layer of deep sutures using 4-0 absorbable material may be required. Alternatively, mattress sutures can be used as well. For deep wounds that penetrate through the muscle fascia and lacerate the muscle belly, closure of the fascial defect with 4-0 absorbable suture is generally recommended. Injuries that involve more than one parallel laceration, classic for suicide attempts, may require horizontal mattress sutures to cross all lacerations for closure to prevent compromising the vascular supply of the island of skin located between incisions (Figure 43-5). Alternatively, adhesive tapes or tissue adhesives alone or in conjunction with sutures may be used. PALM LACERATIONS The palmar skin surface is well adapted for contact with objects in the environment. Palmar skin is thicker than dorsal skin and has an under lying connective tissue fascial layer, making it much more adherent to bone. The thenar, palmar, and digital creases are connections between the skin and underlying fascia, and these areas have no intervening adipose tissue. Because tendons, nerves, and arteries course through this area, palm lacerations have great potential to damage these deep struc tures through small and innocuous-appearing lacerations. 25,26 Carefully assess digital flexor tendon function and two-point discrimination. Carefully approximate creases during skin closure. The thickness of palmar skin makes eversion of the edges especially difficult. For this reason, interrupted horizontal mattress sutures with 5-0 nonabsorb able monofilament are recommended to ensure that sutures do not pull through the skin. FLEXOR TENDON LACERATIONS Flexor tendon injuries are usually repaired in the operating room by a hand surgeon because of the complexity of the anatomy and the reparative procedures required. Early consultation is important, as many sur geons prefer to repair complete flexor tendon lacerations within 24 hours after injury. If operative repair of the flexor tendon is going to be delayed, the wound should be appropriately cleaned and irrigated, the skin closed, and the affected extremity splinted. Splint with the wrist and metacarpophalangeal joint flexed and the proximal interphalangeal and distal interphalangeal joints in extension to prevent contraction of the surrounding muscles. The hand surgeon can follow up with the patient in 2 to 3 days to schedule the flexor tendon repair within 7 days of the injury.

. Splint with the wrist and metacarpophalangeal joint flexed and the proximal interphalangeal and distal interphalangeal joints in extension to prevent contraction of the surrounding muscles. The hand surgeon can follow up with the patient in 2 to 3 days to schedule the flexor tendon repair within 7 days of the injury. Timely repair is important to restore vascular and synovial flow to the area and because postinjury scarring and tendon retrac tion make flexor tendon repairs more difficult after 10 to 14 days. Patients with suspected partial flexor tendon lacerations should also have follow-up with a hand surgeon because unrepaired partial flexor digitorum superficialis disruption can produce a trigger finger. FINGER LACERATIONS In general, isolated finger lacerations are straightforward injuries to examine and repair. Vascular status is checked by capillary refill, and sensory nerve status is checked by static two-point discrimination. Assess motor function of the extensor and flexor mechanisms. Careful examination and wound exploration of hand and digit lacerations are important, regardless of size. About half of patients with metacarpal or digit lacerations <2 cm in size have an associated deep structure injury, most commonly a tendon, with extensor tendon defects more common than flexor tendon injuries. Simple interrupted sutures with 5-0 nonabsorbable suture provide adequate closure for most digital lacerations. Alternatively, small, <2 cm, clean, and uncomplicated hand and digit lacerations can be treated conservatively without wound closure. 28 Although there appears to be no difference in cosmetic appearance or time to return to normal function without wound closure compared with wound closure, this practice has not been widely adopted. DIGITAL AMPUTATIONS Deep finger lacerations may include partial or complete amputations of the digit. Amputations should involve the consultation of a hand sur geon to discuss the possibility of replantation. Relative indications for replantation are injuries in children, injuries to the thumb, multiple digit TABLE 43-4 Flexor Tendons in the Forearm Flexor Tendon Function Flexor carpi radialis Flexes and radially deviates wrist Flexor carpi ulnaris Flexes and ulnarly deviates wrist Palmaris longus Flexes wrist Flexor pollicis longus Flexes thumb at MCP and interphalangeal joints Flexor digitorum superficialis Flexes index, long, ring, and little digits at MCP and PIP joints Flexor digitorum profundus Flexes index, long, ring, and little digits at MCP, PIP, and DIP joints Abbreviations: DIP = distal interphalangeal; MCP = metacarpophalangeal; PIP = proximal interphalangeal. FIGURE 43-5. Horizontal mattress sutures for multiple parallel lacerations. Tintinalli_Sec06_p0267-0328.indd 296 8/2/19 7:15 PM

itorum profundus Flexes index, long, ring, and little digits at MCP, PIP, and DIP joints Abbreviations: DIP = distal interphalangeal; MCP = metacarpophalangeal; PIP = proximal interphalangeal. FIGURE 43-5. Horizontal mattress sutures for multiple parallel lacerations. Tintinalli_Sec06_p0267-0328.indd 296 8/2/19 7:15 PM CHAPTER 43: Arm, Forearm, and Hand Lacerations 297 amputation, and single-digit amputation proximal to the insertion of the flexor digitorum superficialis.29 The strongest contraindications to replantation are crush and avulsion injuries because neurovascular damage to the amputated digit is significant and functional outcome is poor. Other relative contraindications include multiple levels of injury to the amputated part, prolonged ischemia time (>24 hours) of the amputated part, patients in poor health, or significant comorbid factors, such as diabetes or severe pulmonary or cardiac disease that may lead to significant perioperative mortality. Patient attitudes analyzed by region show a preference for replantation to restore cosmetic appearance despite suboptimal functional outcome noted in Asia compared with Europe and North America. DIGITAL NERVE INJURIES Suspect digital nerve injuries when static two-point discrimination is distinctly greater on one side of the volar pad than the other, or when it is >10 mm. Digital nerve injuries can be repaired using microsurgical techniques either acutely or days to weeks after the injury. Concomitant injuries and wound contamination are the most common indications for delayed repair. Prognosis depends on the specific injury and the age of the patient. Nerve contusions have variable healing, with a range of 12 days to 6 months. Nerve transection injuries do slightly better than crush injuries, but even with microsurgical repair, recovery is often incomplete. FINGERTIP INJURIES Fingertip injuries occur distal to the insertion of the deep flexor and extensor tendons at about the level of the lunula. This location is among the most frequently injured parts of the hand. Such injuries may involve the skin, pulp tissue, distal phalanx, and the perionychium (the nail, nail bed, and surrounding structures) (Figure 43-6). 31,32 The goals of healing are to maintain length and cosmetic appearance and to have the finger tip approach normal sensation and function.  DIGITAL TIP INJURIES WITH SKIN AND PULP TISSUE LOSS ONLY Distal fingertip soft tissue (pulp) amputations that are < 1 cm 2 in size without exposed bone or nail bed involvement can be treated conservatively with serial dressing changes alone (Figure 43-7, line A). 31-33 Apply nonadherent dressing on the wound itself, avoiding the surrounding skin to prevent maceration, followed by standard gauze for additional protection. Instruct the patient to soak the injured fingertip for 10 minutes a day in warm water with added antibacterial soap, followed by tap-water irrigation and application of a new sterile nonadherent dressing. Change dressings daily for the first 10 to 15 days and every other day thereafter. Complete healing may take 4 to 8 weeks. Conservative management of fingertip injuries without bone exposure appears to be superior in terms of cosmetic appearance, improved function, and sensibility of the involved digit, especially in children. For larger avulsions, >1 cm 2, an intact amputated portion can be used as a full-thickness skin graft. The amputated tissue is cleaned and Insertion of extensor tendon Periosteum Nail well Eponychium Lunula Nail bed Hyponychium Insertion of deep flexor tendon Distal interphalangeal joint Ventral floor Nail foldDorsal roof FIGURE 43-6. Anatomy of the perionychium. FIGURE 43-7. Fingertip amputations. (A) Volar angulation without bone exposure. (B) Volar angulation with bone exposure.

n Periosteum Nail well Eponychium Lunula Nail bed Hyponychium Insertion of deep flexor tendon Distal interphalangeal joint Ventral floor Nail foldDorsal roof FIGURE 43-6. Anatomy of the perionychium. FIGURE 43-7. Fingertip amputations. (A) Volar angulation without bone exposure. (B) Volar angulation with bone exposure. (C) Transverse or perpendicular angulation with bone exposure. (D) Dorsal angulation with bone exposure. debrided of nonviable tissue, the undersurface of the skin is defatted with sharp scissors, and the graft is sutured to the defect. A split- or full-thickness skin graft harvested from a distant site can provide wound coverage when the severed skin tip is not available. Two approaches are suggested for dermal avulsion injuries with per sistent bleeding. One approach is to soak the fingertip in 10-20 mL of lidocaine 1% with epinephrine until numb and the bleeding stops. Then examine and clean the wound, apply a topical hemostatic pad, and secure with tube gauze. The other approach is to apply a tourniquet around the proximal phalanx to stop bleeding and create a dry wound. Then three to four layers of tissue adhesive are applied over the open area, allowing each layer to dry before applying the next. The tourniquet is released when the final layer is dry and the wound observed for several minutes to ensure hemostasis.  DIGITAL TIP INJURIES WITH EXPOSED BONE Skin grafting will be unsuccessful if a significant loss of tissue at the fingertip exposes the distal phalanx tuft, as bone does not provide adequate vascularity to support donor tissue.33 Several treatment options exist, and the method used should be based on the best way to preserve the digit length and maintain the sensitivity and functionality of the fingertip. The size and geometry of the injury, the angle of the amputation, and the availability of the amputated tip will determine the options available for repair. If the bony protuberance is <0.5 cm in length and the soft tissue defect is <1 cm2, the bone may be trimmed back using a rongeur and the wound left to heal by secondary intention with wound care, as described in the section “Digital Tip Injuries With Skin and Pulp Tissue Loss Only. ” A dorsal, obliquely angulated wound may be treated in the ED with bone shortening followed by primary closure of the wound using the adjacent volar tissue (Figure 43-7, line D). Fat from the local tissue may need to be trimmed to allow wound closure without tension. The nail should be removed, and the nail bed and surrounding structures should be repaired. Although results are comparable to those following conservative management, shortcomings include loss of length as well as tenderness of the fingertip and some degree of functional disability. Amputations that are angled either in a transverse or volar direction have less favorable outcomes, as there is not always adequate soft tis sue and skin coverage to allow for primary closure and preservation of length (Figure 43-7, lines B, C, and D). Consultation with a hand sur geon is necessary, as these injuries often require techniques beyond the scope of practice of most emergency physicians. Incomplete digital tip amputations, defined by the retention of the neurovascular bundle as well as portions of the underlying bone, require consultation with a specialist for fracture reduction, internal pin fixation, and repair of the soft tissue injury in the operating room. Consult a hand surgeon for a complete digital tip amputation occur ring proximal to the lunula, to evaluate the potential for replantation in the operating room. 33 Replantation of a complete amputation distal to the lunula is not usually advocated for adults because the procedure Tintinalli_Sec06_p0267-0328.indd 297 8/2/19 7:15 PM

d surgeon for a complete digital tip amputation occur ring proximal to the lunula, to evaluate the potential for replantation in the operating room. 33 Replantation of a complete amputation distal to the lunula is not usually advocated for adults because the procedure Tintinalli_Sec06_p0267-0328.indd 297 8/2/19 7:15 PM 298 SECTION 6: Wound Management is technically demanding and has a generally poor prognosis. However, specialist consultation is indicated in patients with specific occupational concerns and when the affected digit is the thumb or index finger. Although fingertip injuries are quite common in children, most require only conservative management owing to the rapid healing ability of the young. Repairs in young children should be done using absorb able sutures to eliminate the need for suture removal, as suture removal often requires repeat procedural sedation. INJURIES INVOLVING THE NAIL AND NAIL BED The nail, nail bed, and surrounding soft tissue make up the peri onychium (Figure 43-6). The nail bed is made up of the germinal and sterile matrices. The germinal matrix begins at the proximal base of the nail (typically 3 to 5 mm proximal to the eponychium) and extends to the lunula. From there, the sterile matrix extends distally to the hypo nychium. Nail injuries can be described as simple nail bed laceration, stellate laceration, severe crush, and complete avulsion. Injury to the perionychium is most commonly due to closure of the fingertip in a door and is usually located at the distal portion of the nail bed. The mechanism of injury is a force directed to the dorsum of the nail, caus ing it to bend or break, and crushing the nail bed against the unyielding distal phalanx. Image the involved digit because distal tuft or phalanx fractures are associated with approximately 50% of nail bed injuries. Nail plate deformity permanently affecting nail growth is the most common complication resulting from inadequate treatment.  SUBUNGUAL HEMATOMA Disruption of the blood vessels of the nail bed without fracture of the nail results in accumulation of blood under the nail. A subungual hematoma that covers >50% is treated with trephination of the nail plate to allow decompression and drainage of the hematoma. Various tools for this purpose include a heated paper clip, electric nail drill, hand-held electrocautery, 18-gauge needle, or #11 scalpel. 34-36 (See Video: Subungual Hematoma.) The disadvantages of the heated paper clip include coagulation of the hematoma and introduction of carbon particles into the nail bed, which may delay healing and cause tattooing. Use of a needle, scalpel, or nail drill requires pressure to be applied to the nail and can be painful. A hand-held electrocautery device provides rapid and painless trephina tion. Do not apply alcohol or other flammables to the fingertip before electrocautery, because flames result when cautery is then applied. Simple trephination produces a good to excellent outcome in most patients regardless of subungual hematoma size, injury mechanism, or the presence of fracture. 34,35,37,38 After drainage, instruct patients to soak the affected finger in warm water containing antibacterial soap two to three times a day for 7 days and to follow basic wound-care principles.  NAIL BED INJURIES Nail removal is recommended only if there is associated partial nail avulsion or surrounding nail fold disruption. Nail removal can be accomplished with adequate anesthesia, elevation of the nail off the nail bed using iris scissors, elevation of the eponychium off the nail, and then removal by gentle longitudinal traction with a hemostat. Digital tourniquet application to the digit may be required to adequately visualize the extent of nail bed laceration.

plished with adequate anesthesia, elevation of the nail off the nail bed using iris scissors, elevation of the eponychium off the nail, and then removal by gentle longitudinal traction with a hemostat. Digital tourniquet application to the digit may be required to adequately visualize the extent of nail bed laceration. Lacerations of the nail bed should be carefully repaired using 6-0 absorbable sutures to provide a smooth surface so the nail can grow without cosmetic deformity. Tissue adhesives can also be used to repair small nail bed lacerations by providing an additional structural anchor and minimizing venous bleeding associated with suturing the delicate nail bed tissue. 39 Crush injuries often result in stellate lacerations, which may require extensive, meticulous repair using magnifying loupes for visualization. Nail bed injuries in children can also be repaired with a good outcome. After nail bed repair, replace the removed nail by first gently clean ing it with saline, taking care to avoid damage to the germinal matrix. Once the nail is clean, trephinate the nail to prevent the development of a postrepair subungual hematoma, and secure the nail in its anatomic position. To secure the nail, place a 5-0 nonabsorbable suture through the proximal end of the nail plate, and then pass the suture underneath and through the center of the eponychial fold. Once the nail is secured in its anatomic position, tie the suture down over the nail. The replaced nail acts as a natural splint to the terminal phalanx, prevents formation of synechiae, and protects the sensitive nail bed. 41 If the nail is not available or is significantly deformed, nonbiologic stents or a sterile piece of aluminum foil (such as that used to wrap suture materials) may be fashioned to resemble the avulsed nail, inserted under the eponychium, and sutured in place similar to a replaced nail. However, use of the native nail is preferred. Once the nail is replaced, dress the fingertip with nonadherent gauze and apply a volar splint to limit distal interphalangeal joint movement. Provide postoperative wound-care instructions (e.g., regarding hand elevation as well as neurovascular checks) and adequate pain relief. Unless obvious purulence is noted, leave the dressing undisturbed for 5 to 7 days. At that time, examine the site for new hematoma forma tion. The suture attached to the nail can be removed after 3 weeks. The replaced nail will be dislodged by the new (growing) nail after an addi tional 1 to 3 months of growth. If an associated distal phalanx or tuft fracture coexists with a nail bed laceration, it usually manifests as an avulsion of the nail out of the proximal eponychial fold. In this case, remove the nail, reduce the fracture as needed, and repair the nail bed as described previously. Once replaced in its anatomic position, the nail serves as a biologic splint to maintain fracture reduction owing to its proximity to the underlying bone. Unstable reductions require consultation with a hand surgeon for internal fixation using Kirschner wires to prevent deformity of the nail bed.  NAIL BED AVULSION INJURIES An avulsion or crush injury may tear the nail completely away from the digit, with fragments of germinal matrix tissue left on the underside of the avulsed nail. These matrix fragments should be preserved for use as free grafts and, when possible, reattached to the nail bed using 6-0 or 7-0 absorbable sutures. When the nail or avulsed nail bed fragments are not available, or if the nail bed defect is large, a full-thickness nail bed graft can be harvested from the patient’s toe and sutured into the nail bed of the affected finger. Consultation with a hand surgeon is needed, as these injuries are complex, and repair is technically challenging.

vulsed nail bed fragments are not available, or if the nail bed defect is large, a full-thickness nail bed graft can be harvested from the patient’s toe and sutured into the nail bed of the affected finger. Consultation with a hand surgeon is needed, as these injuries are complex, and repair is technically challenging. Avulsion injuries may also incompletely tear the proximal portion of the nail out from under the eponychium. Replace the nail root into its anatomic position using horizontal mattress sutures ( Figure 43-8). The suture is placed through the eponychial fold and passed through the proximal portion of the corresponding segment of avulsed germinal matrix and then back out through the nail fold, pulling the matrix back to its anatomic position. FIGURE 43-8. A and B. Technique for repair of an avulsion of the germinal matrix using three horizontal mattress sutures. Tintinalli_Sec06_p0267-0328.indd 298 8/2/19 7:15 PM