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1782 SECTION 22: Orthopedics deficit has been observed clinically. Late complications of undiagnosed vascular injuries include thrombosis, arteriovenous fistulas, aneurysm, false aneurysm, and tissue ischemia with limb dysfunction.  COMPARTMENT SYNDROME After a fracture or a direct blow to an extremity, there may be extrava sation of blood, swelling of muscle tissues, and impairment of venous flow within one or more fascial compartments. The resulting increase in pressure within the limb may lead to circulatory compromise, neu rologic damage, and muscle necrosis, known collectively as compartment syndrome. This is a surgical emergency, and early recognition is crucial. Pain with passive stretching, active contraction against resis tance, or direct pressure over the compartment is cause for alarm and suggests need for immediate surgical intervention. The most common site is the anterior compartment of the lower leg, and tissue ischemia begins when compartment pressures exceed 30 mm Hg. Compart ment syndrome is discussed further in Chapter 278, “Compartment Syndromes. ”  DELAYED AND LATE COMPLICATIONS Patients who have sustained a fracture (usually long bone) may be at risk for pulmonary fat embolus, usually originating from the marrow of a large bone, such as the femur. If fat embolism occurs, it is typically within the first few days after injury, rather than the first hours. This event may have a variable effect on pulmonary function, ranging from mild distress to severe or even fatal respiratory failure. An episode can be characterized by the following symptoms: dyspnea, tachypnea, pul monary edema, confusion, or a petechial rash. Treatment is generally supportive. The most delayed complications of fracture include nonunion, malunion (healing with deformity), joint stiffness, traumatic arthritis, reflex dystrophy, avascular necrosis of bone (scaphoid, capitate, and femoral head are particularly prone), and, in the case of open fracture, osteomyelitis.  IMMOBILIZATION COMPLICATIONS Fracture treatment can often result in prolonged periods of immobili zation, which can present further medical problems, especially in the geriatric population. Complications can include infection, deep vein thrombosis, pulmonary embolism, muscle atrophy, and even psychiatric disorders requiring further medical care and possible hospitalization. Avoiding unnecessary immobilization and encouraging early ambula tion should be major goals of optimal orthopedic care. DISPOSITION AND FOLLOW-UP There is no universally prescribed follow-up interval for specific inju ries. Orthopedists differ in their opinions regarding how soon patients should be seen. In general, patients with unreduced fractures or inju ries that may require surgical intervention should be seen within a few days. Sometimes the situation may be discussed with the follow-up physi cian and an appointment arranged while the patient is still in the ED. Alternatively, the emergency physician may instruct the patient to con tact the follow-up physician or clinic as soon as possible. If the name of the injury is written on the discharge instruction sheet, the patient can convey it at the time of the call. This information may help the follow-up physician decide when the patient should be seen. Acknowledgments: The author wishes to thank the following: Jef frey S.

cian or clinic as soon as possible. If the name of the injury is written on the discharge instruction sheet, the patient can convey it at the time of the call. This information may help the follow-up physician decide when the patient should be seen. Acknowledgments: The author wishes to thank the following: Jef frey S. Menkes, MD, who authored this chapter on multiple previous editions; Eleanore Denton Rhodes, AMI, for original artwork; and Joe Driscoll for original photography. REFERENCES The complete reference list is available online at www.TintinalliEM.com. Injuries to the Hand and Digits Brit Long Alex Koyfman ANATOMY The hand consists of 27 bones: 14 phalangeal bones, 5 metacarpal bones, and 8 carpal bones arranged in five rays of metacarpals and phalanges having its base at the carpometacarpal (CMC) articulation (Figure 268-1). The carpal bones are made up of two rows, each with four bones. The bones are concave volarly and are bridged by the flexor retinaculum. This forms the carpal tunnel through which the median nerve and the nine long flexor tendons of the fingers pass (flexor pollicis longus [FPL]; flexor digitorum profundus [FDP] from the index, middle, ring, and small fingers; and flexor digitorum superficialis [FDS] from the index, middle, ring, and small fingers) (Figure 268-2). The index and middle finger CMC articulations have relatively little mobility, whereas the thumb, ring, and small finger CMC articulations have greater mobility at the CMC joint, which allows grasping and adaptive movements of the hand. More metacarpal deformity can be accepted due to the greater mobility of the CMC joints. FIGURE 268-1. A. Bones of the hand and wrist. B. Carpal tunnel. Distal, middle, and proximal phalanges Metacarpals Hook of hamate Hamate Triquetral Pisiform Lunate Distal phalanx of thumb Proximal phalanx of thumb Metacarpal of thumb Trapezoid Trapezium Capitate Scaphoid Flexor retinaculum Opponens pollicis Flexor tendons Median nerve Carpal bones CHAPTER Tintinalli_Sec22_p1767-1880.indd 1782 8/2/19 6:13 PM

al phalanges Metacarpals Hook of hamate Hamate Triquetral Pisiform Lunate Distal phalanx of thumb Proximal phalanx of thumb Metacarpal of thumb Trapezoid Trapezium Capitate Scaphoid Flexor retinaculum Opponens pollicis Flexor tendons Median nerve Carpal bones CHAPTER Tintinalli_Sec22_p1767-1880.indd 1782 8/2/19 6:13 PM CHAPTER 268: Injuries to the Hand and Digits 1783 Multiple soft tissue structures support the bones and joints of the hand: capsules and ligaments provide stability, whereas muscles/tendons of the hand and forearm generate mobility (Figures 268-2, 268-3, and 268-4). The collateral ligaments of the metacarpophalangeal (MCP) joints are tightest in flexion in the index through small fingers (to allow stability in grasp), while the collateral ligaments of the MCP thumb are tight in flexion and extension (which also provide stability for the thumb in all positions) (Figure 268-3). The collateral ligaments of the interphalangeal (IP) joints are also tight throughout the entire range of motion.  INTRINSIC HAND MUSCLES The intrinsic muscles of the hand are those that have both their ori gins and insertions within the hand. They consist of the thenar and hypothenar muscles, the adductor pollicis, the interossei, and the lum bricals (Figures 268-3, 268-4, and 268-5). The thenar muscles (from superficial to deep: abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis) originate in the flexor retinaculum and carpal bones and insert on the radial base of the thumb proximal phalanx and the radial aspect of the first metacarpal. The motor branch of the median nerve innervates all three muscles except for the deep head of the flexor pollicis brevis, which is innervated by the ulnar nerve. The adductor pollicis is innervated by the ulnar nerve and originates from the capitate and second and third metacarpals and inserts on the ulnar base of the thumb proximal phalanx. The hypothenar muscles include, from superficial to deep, the abductor digiti minimi, the flexor digiti minimi, and the opponens digiti minimi. These muscles, innervated by the ulnar nerve, originate in the Lateral band of extensor tendon Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Central slip of extensor tendon Distal interphalangeal joint Proximal interphalangeal joint Collateral ligament Metacarpophalangeal joint Metacarpal bone Proximal phalanx Volar plate Middle phalanx Distal phalanx FIGURE 268-2. Joints, ligaments, and tendons of the digits. FIGURE 268-3. A. Palmar (volar) view of the hand showing the relationship of the some of the intrisic muscles, and flexor tendons and sheaths. B. Cross-sectional view of digit at the middle phalanx. C. Lumbricals. Flexor tendons Tendon sheaths Flexor retinaculum Hypothenar muscles Thenar muscles Lumbricals Dorsal digital artery and nerve 3rd dorsal interosseous Palmar digital artery and nerve Dorsal extensor expansion 2nd dorsal interosseous Flexor digitorum superficialis Flexor digitorum profundus Tintinalli_Sec22_p1767-1880.indd 1783 8/2/19 6:13 PM

sheaths Flexor retinaculum Hypothenar muscles Thenar muscles Lumbricals Dorsal digital artery and nerve 3rd dorsal interosseous Palmar digital artery and nerve Dorsal extensor expansion 2nd dorsal interosseous Flexor digitorum superficialis Flexor digitorum profundus Tintinalli_Sec22_p1767-1880.indd 1783 8/2/19 6:13 PM 1784 SECTION 22: Orthopedics Extensor indicis Lateral bands Central slip Dorsal digital extension First dorsal interosseous Abductor pollicis Expansion of abductor pollicis brevis Dorsal branch of radial artery Extensor pollicis longus Abductor pollicis longus Superficial radial nerve Extensor pollicis brevis Abductor pollicis longus Extensor digitorum communis Abductor digiti minimi Extensor digiti minimi Extensor digiti minimi Extensor carpi radialis longus and brevis Dorsal cutaneous branch of ulnar nerve Extensor retinaculum Extensor carpi ulnaris Extensor digitorum communis Extensor indicis proprius 3 - Extensor pollicis longus 4 - Extensor digitorum communis and extensor indicis 1 - Abductor pollicis longus and extensor pollicis brevis 2 - Extensor carpi radialis longus and brevis 6 - Extensor carpi ulnaris 5 - Extensor digiti minimi FIGURE 268-4. A. Dorsal view of the hand showing the extensor tendons and retinaculum, and intrinsic musculature. B. Cross-sectional view with the six extensor compartments. flexor retinaculum and carpal bones and insert at the ulnar base of the small finger proximal phalanx and the ulnar aspect of the fifth metacarpal. There are seven interosseous muscles, all innervated by the ulnar nerve (Figure 268-5). The three palmar and four dorsal interossei lie between the metacarpal bones and originate from them. The palmar interosseous muscle and the palmar portion of the dorsal interosseous muscle have an insertion into the extensor hood. The palmar interosseous muscle adducts the index, ring, and small finger to the midline, which is designated as the middle finger. The dorsal portion of the dorsal interosseous muscle has a tendinous insertion into the base of the proximal phalanx. The dorsal interosseous muscles abduct the fingers away from the midline. The lumbrical muscles (Figure 268-3) do not attach to bone. They arise from the FDP tendons in the palm, course radially near the MCP joints, and attach to tendons or expansions, reinforcing the interosseous lateral band on the radial side of the digit. The median nerve innervates the radial two lumbricals, and the ulnar nerve innervates the ulnar two. The lumbricals flex the MCP joint and extend the IP joints of the index to the small fingers. Lumbrical muscles also play a critical role coordi nating the flexor and extensor systems of the digits.  EXTENSOR AND FLEXOR TENDONS The extensor tendons course over the dorsal side of the forearm, wrist, and hand (Figure 268-4). Nine extensor tendons pass under the extensor retinaculum and separate into six compartments. In the dorsum of the hand, the extensors digitorum communis are connected by juncturae (Figure 268-6). Based on this anatomy, finger extension may still be possible with a complete tendon laceration that is proximal to the juncture. In the finger, the extensor mechanism divides into a central slip that attaches to the middle phalanx and into two lateral bands that join with the tendons of the lumbrical and interosseous muscles, which then attach to the dorsal base of the distal phalanx as the terminal ten don. The central band extends the PIP , while the lateral bands extend the DIP . 1,2 The flexor tendons (flexor carpi radialis, flexor carpi ulnaris, and palmaris longus) course over the volar side of the forearm, wrist, and hand and primarily flex the wrist. The remaining nine tendons (four FDP , four FDS, and the FPL) pass through the carpal tunnel (Figure 268-1).

e lateral bands extend the DIP . 1,2 The flexor tendons (flexor carpi radialis, flexor carpi ulnaris, and palmaris longus) course over the volar side of the forearm, wrist, and hand and primarily flex the wrist. The remaining nine tendons (four FDP , four FDS, and the FPL) pass through the carpal tunnel (Figure 268-1). The FPL goes to the base of the distal phalanx of the thumb. The other four digits have two tendons each ( Figure 268-2). The FDS inserts into the volar, proximal half of the middle phalanx and flexes all the joints it crosses, including the proximal interphalangeal (PIP) joint and MCP joints. The FDP runs deep to the FDS until the level of the MCP joint, at which point it bifurcates. The FDP inserts at the volar base of the distal phalanx and acts primarily to flex the distal interphalangeal (DIP) joint as well as all the PIP and MCP joints. Unlike the extensor tendons, the flexor tendons are enclosed in synovial sheaths, making them prone to deep space infections. Tintinalli_Sec22_p1767-1880.indd 1784 8/2/19 6:13 PM

the volar base of the distal phalanx and acts primarily to flex the distal interphalangeal (DIP) joint as well as all the PIP and MCP joints. Unlike the extensor tendons, the flexor tendons are enclosed in synovial sheaths, making them prone to deep space infections. Tintinalli_Sec22_p1767-1880.indd 1784 8/2/19 6:13 PM CHAPTER 268: Injuries to the Hand and Digits 1785 Dorsal interossei Palmar interossei FIGURE 268-5. Origins, insertions, and actions of the palmar and dorsal interossei. ECU EDQ EDC EIP Juncturae tendinum EPL EPB ECRL APL ECRB Retinaculum Synovial sheaths FIGURE 268-6. Dorsal view of the hand showing juncturae tendinum. APL = abductor pollicis longus; ECRB = extensor carpi radialis brevis; ECRL = extensor carpi radialis longus; ECU = extensor carpi ulnaris; EDC = extensor digitorum communis; EDQ = extensor digitorum quinti; EPB = extensor pollicis brevis; EPL = extensor pollicis longus; EIP = extensor indicis proprius.  VASCULAR SUPPLY The hand and digits are perfused by the radial and ulnar arteries. The radial artery forms the deep palmar arch, whereas the ulnar artery forms the superficial palmar arch. The common digital arteries (in the second, third, and fourth web spaces) arise from the superficial palmar arch (Figure 268-7) and provide blood supply to the fingers. The blood supply to the thumb arises from the princeps pollicis, which is the radial artery as it turns into the palm. The radialis indicis, which is on the radial side of the index finger, arises from the radial artery or the princeps pollicis.  NERVE SUPPLY The radial, ulnar, and median nerves innervate the hand (Figure 268-8). In the hand, the median and ulnar nerves have mixed motor and sen sory function. The superficial radial nerve (C5-T1) provides sensation to the dorsal radial aspect of the hand. The radial nerve extends the fingers and wrist, supinates the hand, and innervates the posterior interosseous nerve. The ulnar nerve (C7-T1) supplies sensory function to the small finger and the ulnar volar half of the ring finger and motor function to the hypothenar muscles, ulnar two lumbricals, interos sei, adductor pollicis, and deep head of the flexor pollicis brevis. The median nerve (C5-T1) supplies sensory function to the thumb, index, middle, and radial volar half of the ring fingers and motor function to the abductor pollicis brevis, opponens pollicis brevis, superficial head of flexor pollicis brevis, two radial-side lumbricals, and thenar muscles. The recurrent median nerve innervates the OAFT muscles (opponens, abductors, flexors of thumb, and thenar eminence) and is pure motor. As the digital nerves course across the palm, they are superficial structures and thus easily injured. Digital nerve sensation and two-point Tintinalli_Sec22_p1767-1880.indd 1785 8/2/19 6:13 PM

rrent median nerve innervates the OAFT muscles (opponens, abductors, flexors of thumb, and thenar eminence) and is pure motor. As the digital nerves course across the palm, they are superficial structures and thus easily injured. Digital nerve sensation and two-point Tintinalli_Sec22_p1767-1880.indd 1785 8/2/19 6:13 PM 1786 SECTION 22: Orthopedics Deep arch Radial artery Flexor carpi radialis muscle Common digital arteries Proximal palmar crease Superficial arch Ulnar artery Flexor carpi ulnaris muscle Abductor pollicis longus muscle Paried (proper) volar digital arteries FIGURE 268-7. The dual blood supply to the hands and digits. PCM DCU FIGURE 268-8. The cutaneous nerve supply in the hand. DCU = dorsal cutaneous branch of ulnar nerve; M = median nerve; PCM = palmar cutaneous branch of median nerve; R = superficial radial nerve; U = ulnar nerve. discrimination should be routinely assessed when evaluating lacera tions of the palm (Figure 268-8). Normal two-point discrimination is 5 mm. Sensation is best tested at the tip of the fifth digit (little finger) for the ulnar nerve, the tip of the second digit (index finger) for the median nerve, and at the dorsal side of the first web space (superfi cial radial nerve). Consult a hand specialist if the extent of injury is uncertain. In the digits, the digital nerves divide into volar and dorsal branches. Knowing the location of these nerves is important to properly perform a digital block (Figure 268-3, cross-sectional view) (See Video: Digital Nerve Block). CLINICAL FEATURES A striking hand injury must not delay the identification and treatment of other potentially life-threatening injuries. After hemorrhage control, assessment involves a detailed history, general hand examination, test ing of nerves and tendons, anesthesia, and direct wound inspection (See Video: Hand Exam). Remove rings from the injured hand/digits (See Video: Ring Removal). Compare with the uninjured hand, especially to identify partial motor or sensory deficits.  HISTORY The history should include the time and cause of injury as well as the position of the hand at the time of injury. Ask about the possibility of associated crush, burn, injection, or chemical exposure. When appli cable, determine the type and amount of chemical to which the patient was exposed. Document the patient’s occupation, avocations, prior hand injuries, and hand dominance to determine the functional impact of the injury. Obtain past medical history including baseline functional status, immunosuppression (diabetes, vascular disease, asplenia), rheumato logic disease, bleeding history, medications, allergies, and smoking, as these factors all affect healing. 1,2  PHYSICAL EXAMINATION Detail the extent of injury by examining and documenting the vascularity, skin integrity, posture of the fingers, and presence of deformity or active bleeding. Table 268-1 provides key elements of the history and physical examination. Ask the patient to demonstrate the hand position at the time of injury. Evaluate injuries with skin violation in a bloodless field. Injuries with the digits in flexion may result in retraction of the cut end of the tendon when the digit is examined in extension. Check bilateral grip strength. Compare general appearance, motor, sensory, Tintinalli_Sec22_p1767-1880.indd 1786 8/2/19 6:14 PM

. Evaluate injuries with skin violation in a bloodless field. Injuries with the digits in flexion may result in retraction of the cut end of the tendon when the digit is examined in extension. Check bilateral grip strength. Compare general appearance, motor, sensory, Tintinalli_Sec22_p1767-1880.indd 1786 8/2/19 6:14 PM CHAPTER 268: Injuries to the Hand and Digits 1787 TABLE 268-1 Hand Physical Examination Examination Finding General inspection Swelling, discoloration, open wound, deformity, penetrating injury, bleeding Puncture wound consistent with fight bite Boutonnière deformity, Jersey finger, mallet finger Rotation deformity of the digits Range of motion (passive and active) Digits 2–5 MCP, PIP, DIP Thumb MCP and IP Palpation Point tenderness Crepitus Anatomical snuffbox tenderness due to scaphoid fracture Tendon (extensor and flexor) FDS and FDP tendon function in all digits Extensor tendon function Ligamentous stability Valgus/varus stress of PIP, DIP, MCP Joint laxity 30-degree with radial stress of thumb MCP joint Vascular Evidence of bleeding, with control of pulsatile bleeding Capillary refill and skin color compared to other extremity, or Doppler assessment Nerve function Median: Thumb opposition/abduction, light touch/two-point discrimination at distal second digit Ulnar: Thumb adduction, Froment sign, light touch/two-point discrimination at distal fifth digit Radial: Extension of all digits and wrist, light touch/two-point discrimination at dorsal thumb CMC joint Abbreviations: CMC = carpometacarpal; DIP = distal interphalangeal; FDP = flexor digitorum profundus; FDS = flexor digitorum superficialis; IP = interphalangeal; MCP = metacarpophalangeal; PIP = proximal interphalangeal. with the volar pulp of the thumb against the radial side of the PIP joint of the index finger. If the patient can maintain the key pinch of the paper against resistance, then the adductor pollicis is relatively strong. Froment’s sign occurs with weak adductor pollicis function and ulnar nerve pathology, displayed when the patient cannot hold the paper and uses the FPL and flexes the IP joint to compensate. All these reviewed maneuvers for the ulnar nerve test intrinsic muscles so that an ulnar nerve injury at the level of the wrist would be revealed by these test maneuvers. To test the radial nerve, have the patient hyperextend the finger MCP joints against resistance, which will test the extensor digitorum com munis tendons. One way to test this is to have the patient put the palm on a table, with fingers flat and hyperextended, and then lift each digit straight up and extend up from the table while keeping the palm flat. Finger resistance can also be checked in this extended, upright position. During this maneuver, it is important to keep the finger MCP joints in hyperextension because the interossei extend the IP joints of the fingers (but flex the MCP joints), and failure to keep the digit in full extension can mislead the examiner into believing the radial nerve is intact. The interossei cannot hyperextend the finger MCP joints. By extending the thumb against resistance, the extensor pollicis longus integrity is con firmed. If a patient has a posterior interosseous nerve (which innervates the majority of the extensor muscles) palsy, the patient will be unable to hyperextend his or her fingers, but may be able to extend the wrist in a radial direction because the extensor radialis longus and extensor radialis brevis are innervated by the radial nerve proper before the posterior interosseous nerve branches. Sensation is determined by two-point discrimination. Normal twopoint discrimination is 5 mm at the volar fingertips. Older patients may have 6 mm of two-point discrimination .

xtensor radialis longus and extensor radialis brevis are innervated by the radial nerve proper before the posterior interosseous nerve branches. Sensation is determined by two-point discrimination. Normal twopoint discrimination is 5 mm at the volar fingertips. Older patients may have 6 mm of two-point discrimination . Compare both injured and contralateral fingers to establish a reasonable baseline, because patients may have preexisting compressive neuropathies such as carpal and cubital tunnel syndrome or previous nerve injuries. Examine the radial and ulnar sides of each finger to determine which digital nerve is injured. Hand specialists recommend repeating two-point discrimina tion testing two to four times on each side of the digit, because patients can guess sensation correctly by chance. At least 80% accuracy is con sidered acceptable. Less than 80% or indeterminate accuracy suggests the possibility of digital nerve injury. A sensory deficit also implies a potential digital artery laceration because of the close proximity of the two.  TESTING OF TENDONS Assess full range of motion of each tendon against resistance and compare with the uninjured side. It is important to test resistance because up to 90% of a tendon can be lacerated with preservation of range of motion without resistance. In addition, the juncturae tendinum contributes to digital extension, so patients with lacerations to the extensor digitorum communis may be able to extend the digit but may not have the same motor power. Pain along the course of the tendon during resistance testing suggests a partial laceration even if strength appears adequate. US of the digits in a waterbath , using a linear high frequency transducer, provides high-resolution images of small-digit structures and can identify tendon lacerations, foreign bodies, and fluid or blood collections (See Video: Waterbath for Finger Exam). US waterbath testing also causes minimal patient discomfort. Test FDP function by checking flexion of the DIP joint against resis tance while holding the PIP and MCP joints in extension. Test the FDS by having the patient flex the PIP joint against resistance while the remaining fingers are held in full extension. When the rest of the fingers are in extension, the FDP of the tested finger cannot fire and the FDS function is isolated. If the test is not performed this way, PIP joint flex ion may be due to the FDP because this tendon also traverses the PIP joint, whereas the FDS does not. To determine whether the central slip is intact, perform the Elson’s test. Hold the PIP joint of the affected finger in flexion (therefore tightening the central slip and loosening the lateral bands) and ask the patient to extend the finger at the PIP . The examiner should resist and tendon function of both hands to assess baseline function. Test range of motion and strength against resistance. Have the patient make a clenched fist to observe the orientation and rotation of the middle and distal phalanxes. All phalanges should be oriented parallel to each other with the nails positioned in the same plane and be pointing toward the scaphoid when the fist is clenched. Circulation is assessed by regional pulses and capillary refill. 1 Doppler assessment can also help assess digital artery flow.  NERVE TESTING To test the median nerve, have the patient flex the IP joint of the thumb against resistance, which tests FPL function. Alternatively, hold the index or middle finger PIP and MCP joints in extension and have the patient flex the DIP joint, which tests FDP function of the index and middle fingers. The “OK” sign will reveal the ability to flex the IP joint of the thumb and the DIP joint of the index finger.

ance, which tests FPL function. Alternatively, hold the index or middle finger PIP and MCP joints in extension and have the patient flex the DIP joint, which tests FDP function of the index and middle fingers. The “OK” sign will reveal the ability to flex the IP joint of the thumb and the DIP joint of the index finger. To test the motor branch of the median nerve, position the thumb in palmar abduction with the palm up. Have the patient resist a force directing the thumb toward the palm, and assess the motor power while palpating the belly of the abductor pollicis brevis muscle to ensure it is contract ing. Abnormal function of the median nerve can result in weakness of thumb opposition and anterior interosseous function. Note that a laceration at the level of the wrist or distal forearm may demonstrate intact FDP function of the index and middle fingers and FPL function to the thumb, because these muscles have been innervated at the proximal forearm. A median nerve injury at the level of the wrist or distal forearm can only be determined by examining two-point discrimina tion in the three and a half radial digits or motor branch integrity to the thenar muscles. To assess ulnar nerve integrity, have the patient spread the fingers apart (finger abduction) and assess motor power by resisting a force pushing the index and small fingers to midline. Alternatively, have the patient cross the fingers. To test thumb adduction (the ulnar nerve innervates the adductor pollicis muscles ), have the patient hold a piece of paper Tintinalli_Sec22_p1767-1880.indd 1787 8/2/19 6:14 PM

and assess motor power by resisting a force pushing the index and small fingers to midline. Alternatively, have the patient cross the fingers. To test thumb adduction (the ulnar nerve innervates the adductor pollicis muscles ), have the patient hold a piece of paper Tintinalli_Sec22_p1767-1880.indd 1787 8/2/19 6:14 PM 1788 SECTION 22: Orthopedics Plane of cross-section Palm Digital nerves Digital artery Lumbrical muscle in sheath Flexor tendon in sheath Palmar aponeurosis Opponens muscles 1st metacarpal Thenar space Palmar interosseous muscles Dorsal subaponeurotic space Dorsal interosseous muscles Digital arteries and nerves Hypothenar muscles 5th metacarpal Flexor tendon on sheath Midpalmar space Extensor tendons FIGURE 268-9. Relationship of nerves, arteries, tendons, and muscles at the level of the metacarpals. TABLE 268-2 Immediate Hand Surgery Consultation Guidelines •  Vascular  injury with signs of tissue ischemia or poorly controlled hemorrhage •  Irreducible  dislocations •  Grossly  contaminated wounds •  Severe  crush injury •  Open  fracture •  Compartment  syndrome •  High-pressure  injection injury •  Hand/finger  amputation extension; if the DIP is loose, then Elson’s test is negative, meaning the central slip is intact and the extension force is being transmitted to the central slip. If the DIP is rigid and the PIP does not extend, Elson’s test is positive, meaning the central slip is not intact and the extension force is being transmitted through the lateral bands to the terminal tendon to the DIP joint. The contralateral finger should be examined. Sometimes the patient can overpower the examiner and should be asked to decrease the extension force on the finger. Lastly, if the patient resists PIP flexion due to pain, a digital block can be placed and the test repeated. ANESTHESIA AND DIRECT WOUND EXAMINATION Anesthesia and direct wound inspection are necessary because partial tendon lacerations or intra-articular injuries are not always readily apparent. Perform the initial motor and sensory exam before anesthesia (Figure 268-9). If pain limits the motor exam, a digital block can be performed and then motor function reassessed. A bloodless field can be facilitated by milking the digit proximally and then applying a local tourniquet or Penrose drain around the base of the digit. The tourniquet should not be stretched to more than 150% of its length and can be held in place with a hemostat. The digit can be milked by wrapping another Penrose drain circumferentially around the entire digit, going from distal to proximal, or by reconfiguring a 4 × 4-inch gauze dress ing into a narrow band and wrapping that circumferentially around the entire digit. Only moderate compression should be used to avoid com pression injury to the digit. Do not leave the tourniquet in place for >20 minutes. If repair may require greater time, intermittent tourniquet release is recommended. Irrigate contaminated wounds copiously with normal saline, and administer antibiotics. Cephalosporins are often the first choice, but tailor antibiotic selection to the particular contaminant. Administer tetanus toxoid as needed.  IMAGING, CONSULTATION, AND DISPOSITION Radiologic evaluation should include at a minimum posteroanterior, lateral, and oblique projections of the hand. Similar projections are used for the digits, except that the radiographic beam is centered over the affected digit(s), so that true posteroanterior and lateral views should be obtained of the affected digit. Evaluate all radiographs for adequacy of view, bony alignment, and individual bone morphology. CT displays greater sensitivity and specificity for fracture than radiograph, although it is usually not required in the emergency setting and can be obtained as an outpatient.

views should be obtained of the affected digit. Evaluate all radiographs for adequacy of view, bony alignment, and individual bone morphology. CT displays greater sensitivity and specificity for fracture than radiograph, although it is usually not required in the emergency setting and can be obtained as an outpatient. It is recommended if intra-articular fracture is suspected but not found on radiograph. 1,2 US is useful to identify fractures, with sensitivity and specificity over 90%, as well as assess reduction of fractures. 3-6 Waterbath US testing may also be used to assess tendon function and presence of rupture. Several studies suggest high sensitivity and specificity for tendon injury, although nerve injury is not assessable with US. 7,8 Actual or suspected injuries of tendons and nerves should be referred to a hand specialist. Whether consultation is provided in the ED or in follow-up (1 to 3 days) depends on local resources. Injuries requiring immediate and delayed follow-up by a hand surgeon are listed in Tables 268-2 and 268-3, respectively. Tintinalli_Sec22_p1767-1880.indd 1788 8/2/19 6:14 PM

rves should be referred to a hand specialist. Whether consultation is provided in the ED or in follow-up (1 to 3 days) depends on local resources. Injuries requiring immediate and delayed follow-up by a hand surgeon are listed in Tables 268-2 and 268-3, respectively. Tintinalli_Sec22_p1767-1880.indd 1788 8/2/19 6:14 PM CHAPTER 268: Injuries to the Hand and Digits 1789 Table 268-4 provides guidelines for immobilization and follow-up for specific hand injuries referred for delayed hand surgery evaluation. Often, the skin can be closed and the hand splinted in the position of function. The wound can be extended and explored at follow-up, with definitive repair performed by the hand specialist. Most hand specialists prefer to do definitive repair of the acute injuries as soon as pos sible so patients should be informed to seek evaluation immediately and not in 2 weeks, as is often instructed. Also, some diagnoses may be missed in the acute stage when patients are in pain and a thorough exam is difficult. Thus, early referral to a hand specialist verifies the diagnosis and can detect other injuries. Although most injuries involving <20% of the tendon are not surgically repaired, hand specialist follow-up and rehabilitation are still necessary to accurately determine the extent of injury, minimize scarring and tendon contraction, and minimize neu roma formation. Primary closure can be completed in the ED for hand lacerations, although contraindications include infected wounds, wounds requiring hand surgery repair, and high infection risk (immunocompromise, bites, puncture wounds, crush injury, open fracture, gross contamination). Patients with dirty wounds and those at risk for infection undergoing primary closure should receive antibiotics. 1,2 For patients with hand or digit lacerations that are sutured in the ED, and when there is no suspi cion of neurovascular or tendon injury, follow-up evaluation and suture removal in the ED should always include repeat hand examination to make sure that significant injuries have not been missed. FLEXOR TENDON INJURIES The most common cause of flexor tendon injury is laceration. Flexor tendon lacerations can be subtle. A hand surgeon should repair all flexor tendon lacerations, and injuries should be referred to a hand surgeon for evaluation within 7 days of injury. 2 Temporary stabilization and loose closure may be performed in the ED, but should occur within 12 hours. Definitive treatment can occur up to 4 weeks after the injury, but as soon as possible is best. In general, flexor tendon lacerations of <25% do not need to be repaired, but it is difficult to make this assessment in the ED. A distal-to-proximal five-zone (I to V) classification system for flexor tendon injuries has been developed based on location, treatment considerations, and prognosis (Figure 268-10). TABLE 268-4 Immobilization for Common Hand Injuries Injury Splint Ligamentous injuries Thumb MCP ulnar collateral ligament rupture

e ED. A distal-to-proximal five-zone (I to V) classification system for flexor tendon injuries has been developed based on location, treatment considerations, and prognosis (Figure 268-10). TABLE 268-4 Immobilization for Common Hand Injuries Injury Splint Ligamentous injuries Thumb MCP ulnar collateral ligament rupture Partial tears Thumb spica, IP free to flex Complete or equivocal Thumb spica (presurgical repair) (See Video: Thumb Spica Splint) Tendon injuries Mallet finger Dorsal splint, full extension at DIP Flexor tendon laceration Dorsal splint, 30-degree wrist flex, 70-degree MCP flexion, 30- to 45-degree PIP flexion (presurgical repair) Dislocations DIP joint Dorsal splint, full extension PIP joint Stable/postreduction Dorsal splint, 30-degree PIP flexion Unstable/postreduction Dorsal splint, 30-degree PIP flexion MCP joint Buddy taping Carpometacarpal joint Dorsal-volar splint Thumb IP joint Dorsal splint, full extension Thumb MCP joint Thumb spica Fractures Distal phalanx Volar or hairpin splint not immobilizing PIP Middle/proximal phalanx Stable/nondisplaced Buddy taping/dynamic splinting Unstable/displaced Radial/ulnar gutter, 90-degree MCP flexion, <15- to 20-degree PIP flexion, <5- to 10-degree DIP flexion Thumb proximal phalanx Thumb spica Metacarpal Index, middle Radial gutter, 20-degree wrist flexion, 90-degree MCP flexion, PIP left mobile (See Video: Radial Gutter Splint) Ring, small Ulnar gutter, 20-degree wrist flexion, 90-degree MCP flexion, PIP left mobile (See Video: Ulnar Gutter Splint) Thumb metacarpal Extra-articular Thumb spica Intra-articular Thumb spica for initial immobilization (presurgical repair) Abbreviations: DIP = distal interphalangeal; IP = interphalangeal; MCP = metacarpophalangeal; PIP = proximal interphalangeal. Note: Hairpin splint: metal-backed splint with foam padding; dynamic splint: spring-loaded splint that allows some motion at unaffected joints while protecting the injured joint, usually available from a hand surgeon or occupational therapist. TABLE 268-3 Delayed Hand Surgery Consultation Guidelines •  Extensor/flexor  tendon laceration (if not repaired in ED) •   Flexor digitorum profundus rupture (closed) (Jersey finger) or extensor digitorum rupture (mallet finger) •  Nerve  injury •  Closed  fractures •  Dislocations •  Ligamentous  injuries with instability Zone I Zone II Zone III Zone IV Zone V No man’s land Lumbrical origin Carpal tunnel Proximal to carpal tunnel Distal to sublimis FIGURE 268-10. Flexor tendon zones and no man’s land. Tintinalli_Sec22_p1767-1880.indd 1789 8/2/19 6:14 PM

njury •  Closed  fractures •  Dislocations •  Ligamentous  injuries with instability Zone I Zone II Zone III Zone IV Zone V No man’s land Lumbrical origin Carpal tunnel Proximal to carpal tunnel Distal to sublimis FIGURE 268-10. Flexor tendon zones and no man’s land. Tintinalli_Sec22_p1767-1880.indd 1789 8/2/19 6:14 PM 1790 SECTION 22: Orthopedics III VII VIII T V T IV T III T II T I FIGURE 268-11. Extensor tendon zones of the hand. T = thumb.  FLEXOR ZONE I Zone I is distal to the insertion of the FDS so that injuries involve the FDP alone. Patients with such injuries lose flexion at the DIP joint. Jersey finger results from hyperextension of the DIP during active flexion, causing avulsion of the flexor digitorum profundus tendon. This most commonly occurs in the dominant fourth digit, or ring finger, due to its anatomic weakness and increased protrusion while grasping. Flexion is preserved at the PIP and MCP , but not DIP . DIP swelling and volar DIP tenderness are common. 10,11 Surgical referral is recommended.10-12  FLEXOR ZONE II Zone II involves the portion of the digital canal occupied by both FDS and FDP tendons (Figure 268-10). This zone is known as no man’s land because injury in this zone has historically resulted in poor outcomes. This is due to the narrow fibro-osseous tunnel that consists of the metacarpals/phalanges. Lacerations in this zone are common, and partial lacerations are more common than complete injuries.  FLEXOR ZONE III Zone III extends from the distal edge of the carpal tunnel to the proximal edge of the flexor tendon pulley system. The lumbrical muscles originate from the FDP tendons in this region. Outcomes are generally favorable.  FLEXOR ZONE IV Zone IV is at the level of the carpal tunnel. The area must be explored carefully because many vital structures traverse this region. Isolated injuries are the exception.  FLEXOR ZONE V Zone V involves injuries to tendons proximal to the carpal tunnel. Injuries here tend to be severe and often involve multiple tendons as well as the median or ulnar nerve (i.e., “spaghetti wrist”). Examine and test all major structures. EXTENSOR TENDON INJURIES The extensor tendons are the most common site of tendon injuries because of the superficial nature of the tendons on the dorsum of the hand. A separate zone classification system (I to VIII) for extensor tendon injuries has been developed for assessing injury patterns, repair techniques, and rehabilitation 13 (Figure 268-11). There is growing opinion that extensor tendon injuries should now be repaired operatively as well, although ED repair has often been the standard of care. In general, extensor tendon lacerations <25% do not need repair. Discuss injuries with associated fracture, gross contamination, neurovascular injury, thumb involvement, and specific patient populations (rheumatologic conditions, professional athletes/musicians, etc.) with a hand surgeon for definitive care. If repair in the ED is elected, 4-0 or 5-0 nonabsorbable braided suture with tapered needle is recommended. 14,15  EXTENSOR ZONE I Zone I involves the area over the distal phalanx and DIP joint. Injury can occur from blunt or sharp trauma. Complete laceration or rupture of the tendon at this level will result in the inability to extend the DIP joint. This injury, called a mallet finger (Figure 268-12), occurs due to forced flexion of the DIP while the joint is in extension. It is the most common tendon injury in athletes. This injury has been classified as type I if there is tendon-only rupture, type II if there is a small avul sion fracture, and type III if >25% of the articular surface is involved. Type I can be treated with the DIP joint immobilized in continuous full extension for 6 to 8 weeks.

most common tendon injury in athletes. This injury has been classified as type I if there is tendon-only rupture, type II if there is a small avul sion fracture, and type III if >25% of the articular surface is involved. Type I can be treated with the DIP joint immobilized in continuous full extension for 6 to 8 weeks. For the best outcome, no flexion of the DIP joint is permitted for the duration of splinting. Thus, instruct patients to not take off the splint. If they do remove the splint to clean the finger and the splint, the DIP should be held in extension. The DIP cannot be allowed to fall into flexion. Splints for the mallet finger can be a Stax or aluminofoam splint as long as the splint holds the DIP in full extension (Figure 268-13). Type II injuries can be treated the same way if on the radiograph the splinted finger in extension shows congruency with the rest of the noninjured articular surface of the distal phalanx on the distal articular surface of the middle phalanx. Other indications for surgery include an open injury and >30% to 50% articular fracture involvement. Chronic untreated mallet finger may result in a swan neck deformity (Figure 268-14). This occurs when the lateral bands are displaced dorsally, resulting in increased extension forces on the PIP joint.  EXTENSOR ZONE II Zone II involves the area over the middle phalanx. Injuries are usually a result of laceration. Injuries to this area are treated similarly to zone I injuries.  EXTENSOR ZONE III Zone III involves the area over the PIP joint. The central tendon is the most commonly injured structure. Complete disruption of the central tendon may result in the volar displacement of the lateral bands, causing Tintinalli_Sec22_p1767-1880.indd 1790 8/2/19 6:14 PM

ed similarly to zone I injuries.  EXTENSOR ZONE III Zone III involves the area over the PIP joint. The central tendon is the most commonly injured structure. Complete disruption of the central tendon may result in the volar displacement of the lateral bands, causing Tintinalli_Sec22_p1767-1880.indd 1790 8/2/19 6:14 PM CHAPTER 268: Injuries to the Hand and Digits 1791 FIGURE 268-12. A. Mallet finger. B. Clinical appearance. FIGURE 268-13. A and B. Splinting for mallet finger. them to be flexors, along with the unopposed FDP . Additionally, the extensor hood retracts, causing extension of the DIP joint, resulting in the Boutonnière deformity (Figure 268-15). Controversy exists regarding whether treatment of zone III injuries should be conservative or operative. Closed injuries are initially treated with the PIP joint immobilized in continuous extension for 5 to 6 weeks and should be followed closely by a hand specialist.  EXTENSOR ZONE IV Zone IV involves the area over the proximal phalanx. These injuries have clinical findings similar to zone III injuries. These injuries are often less likely to have long-term morbidity because the joint is not involved and the tendon at this level is broad and flat.  EXTENSOR ZONE V Zone V involves the area over the MCP joint. Open injuries to this area should be considered human bites until proven otherwise, although patients may provide a history incongruent with injury. Obtain radio graphs to evaluate for retained foreign body and fracture. Wounds from human bites should have delayed repair following hospital admission for a course of broad-spectrum IV antibiotics. This injury may require operative washout. Clean, nonbite wounds can be repaired primarily using mattress sutures to reapproximate tendon edges.  EXTENSOR ZONE VI Zone VI involves the area over the dorsum of the hand. Because the tendons in this area are so superficial, even minor-appearing lacerations may be associated with one or more tendon injuries. If the laceration is proximal to the juncturae tendineae, the patient may be able to extend the involved MCP joint, because extensor forces are transmitted to the juncturae from adjacent extensor tendons. Injuries to zones VI, VII, and VIII typically require advanced suture techniques.  EXTENSOR ZONE VII Zone VII involves the area over the wrist. Repair can be difficult because of the presence of the extensor retinaculum. This thick, fibrous structure FIGURE 268-14. Swan neck deformity. Boutonnière deformity Flexion Extension FIGURE 268-15. Boutonnière deformity. Tintinalli_Sec22_p1767-1880.indd 1791 8/2/19 6:14 PM

VII Zone VII involves the area over the wrist. Repair can be difficult because of the presence of the extensor retinaculum. This thick, fibrous structure FIGURE 268-14. Swan neck deformity. Boutonnière deformity Flexion Extension FIGURE 268-15. Boutonnière deformity. Tintinalli_Sec22_p1767-1880.indd 1791 8/2/19 6:14 PM 1792 SECTION 22: Orthopedics on the dorsum of the wrist contains 12 extensor tendons and six syno vial-lined retinacular compartments. Due to the anatomic complexity of this region, operative repair is needed.  EXTENSOR ZONE VIII Zone VIII involves the area of the distal forearm. Injuries to this area require a thorough exploration to identify all injured structures. The tendons frequently retract into the forearm and must be retrieved and repaired. After repairs in zones V through VII, splinting should occur with the wrist in 15-degree extension, the MCP joint in 15-degree flex ion, and the IP joint in 15-degree flexion in the involved and adjacent digits. LIGAMENTOUS INJURIES AND DISLOCATIONS Soft tissue injuries to the hand are extremely common. Accurate diag nosis and treatment are important to avoid complications such as joint luxation, loss of motion, chronic pain, and deformity.  DISTAL INTERPHALANGEAL JOINT Dislocations of the DIP joint are uncommon because of the firm attachments of the skin and subcutaneous tissue to the underlying bone by osteocutaneous fibers. Additional stability is provided by the flexor and extensor tendons. When dislocations do occur, they are usually dorsal. Longitudinal traction and hyperextension followed by direct dorsal pressure to the base of the distal phalanx usually accomplish reduction. Attempts at reduction should be made after a digital nerve block or other means of anesthesia has been performed. Irreducible cases may be due to the entrapment of an avulsion fracture, the profundus ten don, or volar plate.  PROXIMAL INTERPHALANGEAL JOINT Dislocations of the PIP joint are common hand injuries. The mecha nism is usually due to axial load and hyperextension. Dorsal disloca tion occurs when the volar plate ruptures. Lateral dislocations occur when one of the collateral ligaments ruptures with at least a partial avulsion of the volar plate from the middle phalanx. The digit is usually ulnarly deviated because the radial collateral ligament is six times more likely than the ulnar collateral ligament to rupture. Volar dislocations are rare but may be associated with central slip rupture. Dorsal dislocations are reduced in the same manner as dorsal DIP joint dislocations. Active motion and strength should be tested fol lowing reduction. If testing is normal, splint the joint at 30 degrees of flexion for 3 weeks. If the joint is irreducible or there is evidence of complete ligamentous disruption, operative repair is required . Untreated PIP dislocation with volar plate tear can result in swan neck deformity. For volar dislocation, the PIP should be splinted in exten sion after reduction.  METACARPOPHALANGEAL JOINT Dislocations of the MCP joint are usually due to hyperextension forces that rupture the volar plate, causing dorsal dislocation. Subluxation is more common than dislocation. In subluxation, the joint appears to be hyperextended 60 to 90 degrees, and the articular surfaces are still in contact. Reduction for this injury does not involve hyperextension because it might convert a subluxation into a complete dislocation. Reduction is performed by flexing the wrist to relax the flexor ten don and then applying pressure over the dorsum of the proximal phalanx in a distal and volar direction. After reduction, splint the MCP joint in flexion. Multipart dislocations appear less deformed because of the number of disrupted structures.

cation. Reduction is performed by flexing the wrist to relax the flexor ten don and then applying pressure over the dorsum of the proximal phalanx in a distal and volar direction. After reduction, splint the MCP joint in flexion. Multipart dislocations appear less deformed because of the number of disrupted structures. Because the volar plate is interposed in the MCP joint space, closed reduction is usually not possible. Volar dislocations are rare and usually require operative reduction.  CARPOMETACARPAL JOINT Dislocations of the CMC joint are uncommon because the joint is supported by strong dorsal, volar, and interosseous ligaments and is reinforced by the broad insertions of the wrist flexors and extensors. The cause is usually a result of high-speed mechanisms such as motor vehicle crashes, falls, crushes, or clenched fist trauma. If a dislocation occurs, it is usually dorsally oriented and associated with fracture(s). Reduction of dorsal CMC joint dislocations can be attempted after regional anesthesia is administered. Traction and flexion with simultaneous longitudinal pressure on the metacarpal base should reestablish normal anatomic alignment. Early referral after reduction is needed to determine if further fixation is needed. Volar CMC joint dislocations are exceedingly rare and should be referred to a hand specialist.  THUMB INTERPHALANGEAL JOINT Dislocations of the thumb IP joint are rare but, if present, are usually open. The mechanism is typically hyperextension with rupture of the volar plate. Reduction is similar to that of the IP joints of the other digits. After reduction, the joint should be immobilized in 15 to 20 degrees of flexion for 3 weeks.  THUMB METACARPOPHALANGEAL JOINT Dislocations of the MCP joint of the thumb are usually dorsal and result from a hyperextension force causing rupture of the volar plate. The dislocation may be simple or complex. Reduction, after radial nerve block, is accomplished with pressure directed distally on the base of the proximal phalanx with the metacarpal flexed and abducted.  THUMB METACARPOPHALANGEAL (ULNAR) COLLATERAL LIGAMENT RUPTURE Rupture of the ulnar collateral ligament ( gamekeeper’s thumb, skier’s thumb) occurs when the mechanism causes radial deviation (abduc tion) of the MCP joint. This injury is more commonly due to chronic laxity of the MCP , rather than acute tear. The tear usually occurs at the insertion into the proximal phalanx. Often significant injury to the dorsal capsule and volar plate occurs. A Stener lesion refers to interposition of the adductor aponeurosis/adductor pollicis muscle between the ulnar collateral ligament and MCP , which requires sur gery. Hand surgery referral within 7 days is recommended for all patients with suspected complete tears of the ulnar collateral liga ment of the thumb , signs of which are pain, ecchymosis of the thumb MCP , and weakness of pinch. The diagnosis is made with stress testing of the ulnar collateral ligament. The examiner tests the thumb MCP joint, both in full extension and 30-degree flexion, by stabilizing the metacarpal with one hand while applying lateral (radial) stress on the proximal phalanx with the other. More than 30 to 35 degrees of radial angulation or 10 to 15 degrees more than the contralateral thumb indicates complete rupture and requires surgical consultation. Partial tears are treated with splinting. If patients are discharged from the ED, a thumb spica splint should be applied and urgent orthopedic follow-up arranged. Repair is best accomplished within 1 week. Radial collateral ligament rupture is not as common, and the mechanism is forced adduction. This injury can lead to avulsion fracture and chronic instability.

patients are discharged from the ED, a thumb spica splint should be applied and urgent orthopedic follow-up arranged. Repair is best accomplished within 1 week. Radial collateral ligament rupture is not as common, and the mechanism is forced adduction. This injury can lead to avulsion fracture and chronic instability. Examination with the same parameters applied in the ulnar direction is used to make the diagnosis of a complete radial collateral ligament rupture.  THUMB CARPOMETACARPAL JOINT Isolated thumb CMC joint dislocation is rare compared with the more common Bennett’s fracture dislocation (see below). These are easy to reduce but unstable after reduction. After reduction, a thumb spica splint should be applied. These injuries should have a surgical referral for a decision on operative repair. Tintinalli_Sec22_p1767-1880.indd 1792 8/2/19 6:14 PM

ompared with the more common Bennett’s fracture dislocation (see below). These are easy to reduce but unstable after reduction. After reduction, a thumb spica splint should be applied. These injuries should have a surgical referral for a decision on operative repair. Tintinalli_Sec22_p1767-1880.indd 1792 8/2/19 6:14 PM CHAPTER 268: Injuries to the Hand and Digits 1793 FRACTURES OF THE PHALANX AND METACARPALS  DISTAL PHALANX Fractures of the distal phalanx usually result from crush or shearing forces. The fractures can be classified as tuft, shaft, or intra-articular. Tuft fractures are the most common distal phalanx fracture and can be associated with nail bed lacerations. Fractures at the base may be associated with flexor or extensor tendon involvement. Generally, fractures of the distal phalanx are treated as soft tissue injuries with protective splinting. Subungual hematoma with an intact nail plate should be drained if it covers more than 50% of the nail bed. If the nail plate is damaged, it may need to be removed with repair of the nail bed including placement of a protective covering, suturing the covering in place, and splinting. Prophylactic antibiotics offer no benefit to low-risk open tuft fractures.  PROXIMAL AND MIDDLE PHALANX The proximal phalanx has no tendinous attachments, so fractures frequently result in apex volar angulation from the forces of the exten sor and interosseous muscles. Greater than 25 degrees of angulation can cause loss of flexion and extension. 18 For the middle phalanx, the FDS tendon inserts on the proximal volar half and the extensor ten don inserts at the proximal base. Therefore, fractures at the base of the middle phalanx demonstrate apex dorsal angulation, and fractures at the neck result in apex volar angulation. A direct blow mechanism usually causes a transverse or comminuted fracture, whereas a twisting mechanism will more often result in a spiral fracture. Most often, such fractures are stable and nondisplaced and can be treated with early protected motion by buddy taping. Unstable fractures amenable to closed reduction can be splinted from the MCP to the DIP joint with the MCP joint in 70 degrees of flexion and the IP joints in extension. Midshaft transverse fractures, spiral fractures, and intra-articular fractures often require internal fixation.  METACARPAL (SECOND TO FIFTH) FRACTURES The second and third metacarpals are relatively immobile, and fractures require anatomic reduction. Metacarpal fractures account for 30% of hand fractures. 19 The ring and fifth metacarpals have 15- to 20-degree anteroposterior motion, which allows for some compensation for mal union. Metacarpal fractures are categorized as head, neck, shaft, or base fractures. 20 The presence of a metacarpal fracture should prompt close evaluation of the associated CMC joint, because CMC joint dislocation often accompanies these fractures and is often missed at the initial presentation.  METACARPAL HEAD FRACTURES Fractures of the metacarpal head are usually caused by a direct blow, crush, or missile. These fractures are distal to the insertion of the collateral ligaments and are often comminuted with significant joint disruption. If a laceration is present, a human bite must be considered. Treatment consists of ice, elevation, and immobilization with referral to a hand surgeon.  METACARPAL NECK FRACTURES Fractures of the metacarpal neck are usually caused by a direct impac tion force. A fracture of the fifth metacarpal neck is often referred to as a boxer’s fracture. Imbalance of extrinsic and intrinsic musculature from metacarpal neck fracture can result in pseudoclaw deformity. These fractures are usually unstable with volar angulation.

acarpal neck are usually caused by a direct impac tion force. A fracture of the fifth metacarpal neck is often referred to as a boxer’s fracture. Imbalance of extrinsic and intrinsic musculature from metacarpal neck fracture can result in pseudoclaw deformity. These fractures are usually unstable with volar angulation. Angulation of ≤20 to 30 degrees in the fourth and ≤40 degrees in the fifth metacarpal will not result in functional impairment. If greater angulation in these metacarpals occurs, reduction should be attempted. 22 To per form the reduction, flex the wrist and the MCP joint. Apply slight force to the volar aspect of the affected metacarpal while distracting the pha lanx away from the palm. Following splinting, patients may have resid ual cosmetic deformity (decreased prominence of the metacarpal head), but in most cases regain full function. The amount of angulation at the time of injury does not correlate with resultant cosmetic defects. 23 With second and third metacarpal fractures, angulation of <15 degrees is acceptable. 22 However, rotational deformity is not acceptable. 22 Splint metacarpal neck fractures with the wrist in 20-degree extension and the MCP joint flexed at 70 degrees. Extend the splint to cover the DIP . Obtain radiographs after splinting, with neurovascular reassessment. Fractures of the second or third metacarpal that are significantly dis placed or angulated require anatomic reduction and surgical fixation.  METACARPAL SHAFT FRACTURES A direct blow usually results in fractures in the metacarpal shaft region. Rotational deformity and shortening are more likely in shaft fractures than in neck fractures. Minimally or nondisplaced injuries without significant angulation, rotation, or shortening can be immobilized. Typically no angulation is acceptable for the second and third metacarpals, while 20 degrees and 30 degrees are acceptable for the fourth and fifth digits, respectively. 22 If manipulative reduction is necessary, operative fixation is usually indicated.  METACARPAL BASE FRACTURES Fractures at the base of the metacarpal are usually caused by a direct blow or axial force and often associated with carpal bone fractures. CMC joint subluxation or dislocation should be suspected with these injuries. Given the overlap of the bones and joints on the lateral radiograph, a CT scan may be needed to definitively rule out joint subluxation or dislocation. Fractures at the base of the fourth and fifth metacarpals can result in paralysis of the motor branch of the ulnar nerve, although this is rare. 24 Management is controversial, and orthopedic consultation is recommended, as many patients require operative intervention.22  THUMB METACARPAL FRACTURES Because of the mobility of the thumb metacarpal, shaft fractures are uncommon. Fractures usually involve the base. Extra-Articular Fractures Extra-articular fractures are caused by a direct blow or impaction mechanism. The mobility of the CMC joint can allow for 30-degree angular deformity. Angulation greater than this requires reduction and a thumb spica splint for 4 weeks. Spiral fractures often require fixation. Intra-Articular Fractures: Bennett’s Fracture and Rolando’s Fracture Intra-articular fractures are caused by impaction from strik ing a fixed object. Bennett’s fracture is an intra-articular fracture with associated sub luxation or dislocation at the CMC joint. The ulnar portion of the metacarpal usually remains in place (“constant fragment”). The distal portion usually subluxes radially and dorsally from the pull of the abductor pollicis longus and the adductor pollicis. Treatment is application of a thumb spica splint and orthopedic referral. Rolando’s fracture is an intra-articular comminuted fracture at the base of the metacarpal.

(“constant fragment”). The distal portion usually subluxes radially and dorsally from the pull of the abductor pollicis longus and the adductor pollicis. Treatment is application of a thumb spica splint and orthopedic referral. Rolando’s fracture is an intra-articular comminuted fracture at the base of the metacarpal. The mechanism of injury is similar to Bennett’s fracture but less common. Treatment includes a thumb spica splint and orthopedic consultation.  SPECIAL CONSIDERATIONS COMPARTMENT SYNDROME OF THE HAND Crush injury of the hand, with or without associated fracture, may result in compartment syndrome. Iatrogenic causes of compartment syndrome of the hand include extravasation of IV fluids or contrast media or arterial punctures. 25,26 The involved compartments of the hand include the thenar, hypothenar, adductor pollicis, three palmar, and four interossei muscles (see Figure 278-3). Edema of tissues or hemorrhage within any of these compartments may lead to elevated pressures that result in tis sue necrosis and subsequent loss of hand function due to contracture. Classic signs and symptoms of compartment syndrome typically include Tintinalli_Sec22_p1767-1880.indd 1793 8/2/19 6:14 PM