Chapter 6 – Musculoskeletal Injury




Abstract




Orthopedic injuries are found in approximately 85% of blunt trauma victims; thus knowledge of their evaluation and treatment is important. Some of these injuries are also acutely life- or limb-threatening and need to be treated in an expedited fashion. Despite the importance of early treatment, the standard primary survey promulgated by the ATLS course is necessary to detect other injuries that have a higher priority. During the primary survey, the only attention to musculoskeletal injury is acute hemorrhage control with direct pressure.





Chapter 6 Musculoskeletal Injury


Carl R. Chudnofsky and Edward J. Newton



Introduction


Orthopedic injuries are found in approximately 85% of blunt trauma victims; thus knowledge of their evaluation and treatment is important. Some of these injuries are also acutely life- or limb-threatening and need to be treated in an expedited fashion. Despite the importance of early treatment, the standard primary survey promulgated by the ATLS course is necessary to detect other injuries that have a higher priority. During the primary survey, the only attention to musculoskeletal injury is acute hemorrhage control with direct pressure.



Clinical Examination


The physical exam is an integral component of detecting acute orthopedic injuries. Examine the overlying skin for contusions and lacerations. Explore all lacerations for neurovascular injury, tendon injury, foreign bodies, and proximity to fracture sites. Cool, pale skin may indicate acute vascular insufficiency. Check capillary refill and peripheral pulses of injured extremities and compare them to the unaffected limb whenever possible. In some cases, doppler ultrasound may be required to detect poor pulses. Palpate muscle compartments for firmness that may indicate an acute compartment syndrome. General range of motion and areas of tenderness help guide necessary radiographs. Careful peripheral nerve exam is also important, as nerve injury may be part of the injury complex.



Investigations




  1. 1. Plain X-rays are indicated for most orthopedic injuries. Fractures are usually evident on plain radiographs, but occasionally the fracture is occult, requiring further imaging (i.e., CT) that is generally guided by the clinical exam. Obtain X-rays of the affected bone in at least two perpendicular planes and be sure that the films provide a full view of the involved bone, including the joints above and below the suspected injury. Depending on the spectrum of injuries, full radiographic evaluation may need to be delayed in order to treat life-threatening injuries.



  2. 2. CT scan is useful in evaluating patients with continued pain and normal X-rays, such as in acute hip injuries. CT scans also provide much more detail of an identified injury and allow 3-D reconstruction.



  3. 3. MRI is rarely needed to acutely evaluate musculoskeletal injuries. It is useful in detecting occult fractures, as in hip injuries, and is also useful in delineating ligamentous and cartilaginous injuries, such as may be seen with acute knee trauma. It also has a prominent role in the evaluation of spinal injuries.



  4. 4. Bone scanning at 72 hours is occasionally used to follow-up patients who may have occult fractures of the scaphoid.



  5. 5. Doppler ultrasound or CTA are used to evaluate patients with possible vascular injury.



  6. 6. Intracompartment pressure can easily be measured with portable equipment and can help guide the management of patients with possible compartment syndrome (see Chapter 10, Extremity Compartment Syndrome).



General Management


Life-threatening injuries receive priority, and thus many orthopedic injuries receive more extensive evaluation and treatment after initial stabilization and treatment of more critical injuries. Some orthopedic injuries, however, may be life-threatening and require similar prioritization. Major pelvic fractures are associated with significant retroperitoneal hemorrhage, which is often difficult to control. Liberal blood transfusions, expedited stabilization of the fracture, and emergency angiography with embolization may be necessary to restore hemodynamic stability. Major arterial injury with exsanguination may occur with penetrating injury or by blunt force with fracture or dislocation-induced vessel laceration. Depending on the involved vessel and the clinical status of the patient, emergency operative therapy may be necessary to control bleeding. Significant soft tissue destruction may cause rhabdomyolysis that can lead to acute renal failure if not promptly managed with vigorous intravenous hydration, diuretics, and alkalinization of the urine.


Open fractures and open joints are limb-threatening and need irrigation, tetanus immunization, and parenteral antibiotics. Formal operative debridement is done on an emergent basis. Traumatic amputations will need to be considered for emergency reimplantation, and the amputated part appropriately cared for. Compartment syndrome may develop over hours, and thus high-risk injuries need serial physical examinations and compartment pressure monitoring. Dislocations need prompt reduction, often with deep sedation. Check the neurovascular status of the involved limb before and after the reduction. Closed fractures need at least gross alignment with splinting in the emergency department to decrease bleeding and pain, and prevent further displacement and injury of the adjacent neurovascular structures. Definitive closed or open reduction can be completed once the patient has been stabilized from other injuries.



Tips and Pitfalls




  1. 1. Significant occult blood loss can occur with fractures of large bones such as the femur and pelvis and can often account for acute hemorrhagic shock. Anticipate large blood loss with these injuries while excluding other causes of hemorrhage.



  2. 2. Compartment syndrome may insidiously develop in the multiple trauma patient, and thus frequent reassessment of the injured part is paramount. Pain out of proportion to the apparent injury is an early symptom necessitating compartment evaluation. Segmental fractures in long bones such as the tibia are especially susceptible to compartment syndrome.



  3. 3. Neurovascular injury complicates many fractures and needs to be carefully sought. The ankle-brachial index (ABI), doppler-determined arterial pressure in the affected limb divided by the pressure in the unaffected limb (API), doppler ultrasound, or CTA may be needed to delineate acute vascular injury.



  4. 4. Occult fractures should be suspected in patients with significant pain and normal radiographs. Additional plain X-rays, CT scan, and MRI, may be necessary for fracture identification.



  5. 5. Pediatric X-rays are inherently more difficult to interpret because of osseous growth plates and incomplete ossification. At times, comparison views of the other extremity will be necessary. Suspect occult fractures in children with tenderness over the physis.



  6. 6. Long bone fractures should be splinted before transferring the patient to the radiology suite or other location. Immobilization of the fracture reduces pain and bleeding and prevents further damage to surrounding neurovascular structures.



Classification of Fractures


Correct terminology is necessary and allows clear communication when describing orthopedic injuries. Fractures are first described by anatomic location, and long bones are usually divided in thirds, describing the location of the injury. Open or compound fractures refer to fractures with a break in the overlying skin, in contrast to closed fractures, which have normal skin integrity.


The fracture line or pattern is then described and adheres to the following common convention (Figure 6.1):





Figure 6.1 Illustration of fracture pattern types.





  1. 1. Transverse: fracture line perpendicular to the long axis of the bone



  2. 2. Oblique: fracture line oblique to the long axis of the bone



  3. 3. Spiral: fracture line curved in a spiral fashion



  4. 4. Comminuted: fracture with two or more pieces



  5. 5. Segmental: fracture at two distinct levels



  6. 6. Torus: wrinkling or buckling of the bone cortex seen in children



  7. 7. Greenstick: incomplete fracture, seen in children


Displacement refers to the degree of offset of the bone ends relative to one another, and is described by the position the distal bone relative to the proximal end. A bayonet deformity refers to injuries with 100% displacement and overriding bone ends with shortening of the affected extremity. Completely displaced fractures tend to be more unstable.


Angulation refers to the angle between the longitudinal axes of the main fracture segments. Fractures with significant angulation generally require reduction to maintain proper function.



Open Fractures


Open fractures are true orthopedic emergencies. They are defined as fractures in contact with the outside environment and thus require a break in the skin overlying the fracture site. The skin break may be large and obvious or small and obscure (e.g., puncture wound), and determining whether or not a fracture is open can sometimes be difficult (Figure 6.2 AC).





Figure 6.2 A–C Open fracture of mid-tibia (A), elbow (B), and knee (C).


Osteomyelitis, often due to staphylococcus, is a concerning complication of open fractures. Thus all patients with open fractures should receive antibiotic therapy at minimum, active against this organism. Emergency therapy also includes covering the wound with saline moistened sterile dressings, tetanus immunization (if required), and pain management. All open fractures of large bones require early operative irrigation and debridement, while mangled extremities may require more complex emergent operation or amputation.



Mangled Extremity


Mangled extremities are commonly the result of severe crush trauma, high-velocity missiles, or shotgun injuries. There is a combination of orthopedic trauma, extensive soft tissue damage, and injury to the neurovascular structures. The most immediate priority is hemorrhage control, often by the use of tourniquets in the appropriate cases. The initial clinical evaluation should include assessment of the extent of skeletal and soft tissue injury, the presence of peripheral pulses and skin perfusion, and motor and sensory function. Patients with obvious nonsalvageable limbs should be transferred to the operating room for bleeding control and amputation. Investigations should be reserved only for cases with possibly salvageable limbs. In these cases, X-rays should be obtained to determine the extent of the fractures. Color flow doppler studies, CTA, or conventional angiography may be necessary to assess the vascular structures and plan any vascular reconstruction.


The severity of the mangled extremity and the prediction of the need for amputation are commonly assessed with the Mangled Extremity Severity Score (MESS), which takes into account the extent of the skeletal/soft tissue injury, the presence and duration of limb ischemia, the presence of shock on admission, and the age of the patient. High scores (e.g., >7) are predictive of the need for amputation. Although this scoring system is a useful tool, it has significant limitations and should not be the sole criterion in determining the need for amputation or salvage operations (Figure 6.3 AE).





Figure 6.3 A–E Mangled right arm with severe crush injury. This patient accidentally placed his arm into an industrial mixer. Amputation was required (A). Mangled lower legs bilaterally, following a train accident. The patient required bilateral amputations (B). Mangled leg following a motorcycle accident. There is extensive soft tissue loss with neurovascular injury. The patient required amputation (C). Mangled lower leg with fairly limited crushing and loss of skin and muscle. The popliteal vessels were transected. Note the tourniquet above the knee, which was placed to control severe bleeding. The patient underwent successful reconstruction (D). Near-complete amputation of the leg following a motorcycle accident. There is only a bridge of skin holding the leg in one piece (E).



Open Joint Injury


Open joint injuries are serious orthopedic emergencies, with septic arthritis and osteomyelitis being common complications. Detection may be obvious on physical exam or findings may be subtle, requiring adjunctive testing. Any deep wound in proximity to a joint should be considered intra-articular until proven otherwise (Figure 6.4 AD).





Figure 6.4 A–D Open volar dislocation of the metacarpal joint (A). Photograph (left) and radiograph (right) of an open joint and fracture of the ankle (B). Open joint and fracture of the ankle following a motorcycle accident (C). Photograph of a methylene blue arthrogram of the knee with leakage through the proximal wound signifying an open joint (D).


Plain X-ray after open joint injury can show an associated fracture, air, or a foreign body within the joint, but also may be normal. Careful exploration under sterile conditions may reveal a wound track directly penetrating the joint capsule. In questionable cases, a saline or methylene blue arthrogram may provide the answer by revealing dye leakage through the wound site. Emergency therapy includes broad spectrum parenteral antibiotics, tetanus immunization (if needed), and analgesia. All major open joints require formal exploration and irrigation in the operating suite.



Epiphyseal Injuries


In a growing child, the epiphyseal plate is a weak cartilaginous structure and is predisposed to injury. Injuries most often occur in the zone of hypertrophic cartilage cells, while the germinal cells are usually undamaged, thus, growth is often not affected (Figure 6.5 A-C).





Figure 6.5 A-C (A) Illustration of the Salter–Harris pediatric fracture classification. (B) Radiograph of Salter–Harris fracture involving the proximal phalanx of the thumb. (C) Radiograph of a juvenile Tillaux fracture. This is a Salter–Harris III fracture of the ankle.


The most commonly used classification of epiphyseal injuries is the Salter–Harris classification. In this classification, prognosis becomes progressively worse from Salter-Harris I through Salter-Harris V.




  • Type I: A very common slip through the zone of provisional calcification without fracture. No germinal layer is involved, and the fracture usually heals without consequence. Comparison X-rays are often necessary for diagnosis.



  • Type II: An epiphyseal plate slip with an associated fracture through the metaphysis, forming a triangular fragment. This is a very common fracture type and accounts for three-quarters of all epiphyseal injuries. The prognosis is good.



  • Type III: An epiphyseal plate slip with a fracture through the epiphysis involving the articular surface. This fracture involves the germinal layer, and thus accurate reduction is necessary but does not guarantee avoidance of growth complications.



  • Type IV: Epiphyseal fracture involving both the plate and metaphysis. These fractures are complicated, and significant growth disturbance can occur unless good anatomic reduction is achieved. Operative intervention is often needed in this type of fracture.



  • Type V: Impaction injury in which the epiphyseal plate is destroyed. They are rare and difficult to diagnose. Unfortunately, growth arrest is the rule in this injury.


As with any pediatric injury, consideration should be given to the possibility of nonaccidental trauma.



Torus and Greenstick Fractures


Pediatric bones are much less brittle than adult bones and thus are less likely to have complete fractures through the bone. A torus fracture is an incomplete fracture with a small fold or buckle in the cortex. It is often seen at the end of long bones. A greenstick fracture is an incomplete angulated fracture of a long bone recognized by a bowing appearance. These pediatric variants are common and can be easily missed (Figure 6.6 A,B).





Figure 6.6 A,B Anteroposterior and lateral radiograph of a distal radius torus fracture (A). Lateral radiograph of a distal radius greenstick fracture (B).



Supracondylar Fracture


Distal humerus fractures that are proximal to the epicondyles are termed supracondylar fractures, and most often occur in children age 5–10 years. In children, the ligaments and joint capsule are stronger than the bone, and thus hyperextension injury often causes bone fracture, while adults with a similar mechanism often suffer a posterior dislocation of the elbow (Figure 6.7 AC).





Figure 6.7 A–C Photograph of a swollen elbow of a child suffering a supracondylar fracture. Radiograph of the elbow shows displaced extension supracondylar fracture (A). Radiograph of a minimally displaced transverse supracondylar fracture with the anterior humeral line passing anterior to the capitellum (B). Illustration of the anterior humeral line. Normally this line intersects the middle of the capitellum. With an extension fracture, this line intersects the anterior one-third of the capitellum or passes entirely anteriorly (C).


There are two types of supracondylar fractures; the flexion type, which occurs less often, and the more common extension type. Extension injuries are often the result of a fall on an arm with the elbow fully extended. On exam, the elbow will be swollen, often with a joint effusion and with significant pain and tenderness. In addition, the olecranon will be more prominent, as it is attached to the posteriorly displaced distal fragment. Careful neurovascular examination of the arm is essential, as many of these fractures are complicated by brachial artery and median, radial, or ulnar nerve injury. In addition, compartment syndrome can be seen with displaced fractures and must be considered. If compartment syndrome continues unchecked, ischemic necrosis of muscle and nerves can result in Volkmann’s contracture, leading to permanent dysfunction of the arm and hand. Consequently, children with supracondylar fractures are frequently admitted to the hospital for serial compartment checks.


Radiographically, these fractures are often detected on the lateral view of the elbow. Because many of these fractures are transverse, they may not be readily visible on the anteroposterior view. In addition, up to 25% are of the greenstick variety with the posterior cortex remaining intact. The only abnormality seen may be a posterior fat pad sign or an abnormal anterior humeral line. Supracondylar fracture must be suspected in any child with acute elbow trauma, swelling, and pain, in spite of normal radiography. Most nondisplaced fractures are treated nonoperatively with casting, while most displaced fractures undergo percutaneous pinning.



Amputations


Amputations are devastating injuries and require expert knowledge in the care of the patient and the amputated part. The area affected is important in the decision to attempt reimplantation. Lower extremity reimplantation is rarely indicated, given the frequency of associated crush injury and the efficacy of current prostheses. In contrast, upper extremity traumatic amputations, especially those involving the thumb, are often reimplanted, given the severe disability that occurs with the loss of that single digit. Time elapsed since the injury is an important consideration, as reimplantation is less likely to be successful if the warm ischemia time has been more than 6–8 hours. If the amputated segment has been properly cooled and cared for, then this window of time may be successfully extended to 12–24 hours. In addition, clean, sharp amputations are more likely to be successful than crush injuries. In general, all amputated parts should be considered for reimplantation, since even severely crushed parts can be used for skin coverage (Figure 6.8 AF).





Figure 6.8 A–F Extremity amputations. Photograph of a hand with thumb amputated secondary to a power saw injury (A). The amputated part in saline-moistened gauze (B). Reimplantation was performed. Amputated hand and multiple fingers (secondary to the hand being caught in a gear mechanism). Reimplantation was performed (C, D). Amputated forearm. Reimplantation was performed (E). Amputated foot being cooled in ice-water slurry (F).


Proper care of the amputated part will maximize the chance of successful reimplantation. Avoid antiseptics, debridement, and excessive handling. Irrigate the amputated part with normal saline and then wrap it loosely in saline moistened sterile gauze. Place the gauze-wrapped part in a watertight plastic bag and place the bag in an ice-water mixture.


Similarly, irrigate the patient’s stump with normal saline and apply direct pressure to control any bleeding. As with the amputated part, do not apply antiseptics to the stump. Administer broad-spectrum antibiotics and tetanus immunization as appropriate.



Tendon Injury


Tendon lacerations are important injuries to detect, and full examination of the hand will usually detect complete lacerations. Diagnosis of partial injuries is more difficult, as tendon function often remains intact. A careful examination of the laceration through the full range of motion is necessary, as the injured area of tendon may retract out of the field of view (Figure 6.9).





Figure 6.9 This photograph illustrates the classic position of extension in a patient with finger flexor tendon injury.


Flexor tendon repair in the hand is difficult and fraught with complications. Flexor tendon repair should be performed by an experienced hand surgeon in an operating room, whereas extensor tendon injuries of the hand and fingers can be repaired in the emergency department. Prophylactic antibiotics, tetanus immunization (if needed), and splinting are essential components of emergency management.



Peripheral Vascular Injury


Most peripheral vascular injuries occur as a result of penetrating trauma, with gunshot wounds being more damaging than stab wounds. Fortunately, blunt trauma rarely causes vascular injury except with markedly displaced fractures and dislocations. Prompt identification and repair is important, given the relatively short “golden period” of about 6 hours, after which irreversible ischemic insult will occur.


Physical examination is important for early diagnosis, and most authors divide examination findings into “hard” and “soft” signs. Hard signs of vascular injury include pulsatile bleeding, unexplained hypotension, absent peripheral pulse, expanding hematoma, palpable thrill, audible bruit, or evidence of regional ischemia, such as a pale, cool extremity. In the presence of any of these signs, operative exploration is usually recommended (Figure 6.10 AD, Figure 6.11 AD, Figure 6.12 A,B, Figure 6.13 AD, Figure 6.14, Figure 6.15 A,B).





Figure 6.10 A–D Photograph of a patient with a gunshot wound of the elbow with obvious demarcation of cyanosis distally and absent distal pulses. Pulse oximetry is being used but is not sensitive for detecting vascular injury (A). Gunshot wound with an entry in the posterior thigh and a large groin hematoma anteriorly. The left foot was cool and pale (left). Operative view revealing associated femoral artery injury (right; B). Patients with gunshot wounds to the arm with large hematomas and diminished peripheral pulses. Both patients had injury to the brachial artery (C, D).





Figure 6.11 A–D Gunshot wound to the arm with a bullet tract near the brachial vessels (A). CT angiogram with 3-D reconstruction shows a normal brachial artery. Gunshot wound to the thigh with a stable hematoma (B). CT angiogram with 3-D reconstruction shows a normal superficial artery. Patients with gunshot wounds to the upper thigh. In both patients, CT angiography with 3-D reconstruction shows transection and thrombosis of the superficial femoral artery (arrow; C, D).





Figure 6.12 A,B Gunshot wound to the knee. The patient had diminished peripheral pulses and a bruit on auscultation. Angiography shows an arteriovenous fistula (circle; A). Patient with a stab wound to the right antecubital fossa presenting with a large hematoma, diminished peripheral pulses, and a bruit on auscultation. CT angio shows false aneurysm of the distal brachial artery and an arteriovenous fistula (circle; B).





Figure 6.13 A–D Gunshot wound to the knee and no peripheral pulse on palpation (A). Angiography shows transection and thrombosis of the popliteal artery (arrow). Collateral vessels provide a satisfactory peripheral perfusion. Gunshot wound to the popliteal fossa with no peripheral pulse (B). The leg was cold. Angiography shows transection and thrombosis of the popliteal artery (arrow). Note the absence of collateral circulation. Shotgun injury to the knee with absent peripheral pulses. Angiography shows transection and thrombosis of the popliteal artery (arrow; C). Gunshot wound to the mid-thigh (D). The patient had diminished peripheral pulses and a bruit on auscultation. Angiogram shows injury to the superficial femoral artery and a pseudoaneurysm (circle).





Figure 6.14 Gunshot wound to the thigh with severe active bleeding. Intraoperative photograph shows an injury to the superficial femoral artery (circle; A). The vessel was repaired with a synthetic graft (circle; B).





Figure 6.15 A,B Patient with complex pelvic fractures and absent femoral pulse. Angiography shows thrombosis of the left common iliac artery (circle; A). The thrombosis was successfully managed with an angiographically placed stent-graft (circle; B).


Soft signs include moderate hematoma formation, injury in proximity to major neurovascular tracts, peripheral nerve injury, and diminished but palpable pulses. To assist the evaluation of diminished pulses, the API is often used to screen for injury. An index of >0.9 generally excludes significant injury, and an index of <0.9 mandates further investigation. Though there are variations in the stepwise approach, all patients with soft signs should undergo further diagnostic testing such as color flow doppler, ultrasound, or arteriography to exclude serious injuries requiring operative attention. CTA has become the investigation of choice and has replaced conventional angiography in most cases. It is highly specific and sensitive, not invasive, and can be performed during routine CT scanning.


Besides acute limb loss, patients with peripheral vascular injuries are also at risk for acute compartment syndrome. Late complications of missed injuries include pseudoaneurysm formation, delayed thrombosis, arteriovenous fistula, and intermittent claudication.



Peripheral Nerve Injury


Peripheral nerve injuries, though not life-threatening, can cause significant long-term disability. Nerve injuries are generally classified in the following three groups:




  1. 1. Neuropraxia: Mild transient nerve dysfunction without gross anatomic disruption to the nerve, often secondary to contusion, local ischemia, or prolonged local pressure.



  2. 2. Axonotmesis: More extensive injury with interruption of axons, but with preservation of the neural sheath. Complete loss of motor and sensory function is seen distal to the site of injury. Spontaneous recovery is possible and is dependent on the distance between the site of injury and the peripheral muscles to be reinnervated.



  3. 3. Neurotmesis: Complete severance of the nerve or damage to the point where spontaneous regeneration is impossible. This injury is often seen following direct lacerations, severe contusions, crushing or ischemic compressive injuries, electrical and thermal burns, and chemical injuries (Figure 6.16 AD).





Figure 6.16 A–D Peripheral nerve injuries in the upper extremity. Proximal radial nerve injury with the characteristic wrist drop (A). Ulnar nerve injury with the characteristic abduction and slight flexion of the small flnger (B). Operative view of a transected median nerve before (left) and after repair (right; C) (photograph courtesy of Dr. Milan Stevanovic). Operative view of a partially transected ulnar nerve before (left) and after repair (right; D).


Physical examination can exclude peripheral nerve injury in a conscious, cooperative patient. However, diagnosis of peripheral nerve injury in a comatose or intoxicated patient is extremely difficult and is often delayed. Penetrating injury in proximity to a nerve mandates careful examination and exploration. These injuries are often associated with damage to adjacent blood vessels and tendons. In addition, certain orthopedic injuries are associated with specific peripheral nerve injuries, as outlined in Table 6.1.




Table 6.1 Skeletal injuries and associated nerve injuries




















































Upper extremity injury Lower extremity injury
Nerve injury Upper extremity injury Nerve injury Lower extremity injury
Ulnar Elbow Injury Femoral Pubic rami fracture
Distal median Wrist dislocation Obturator Obturator ring fracture
Median, anterior interosseous Supracondylar fracture Posterior tibial Knee dislocation
Musculocutaneous dislocation Anterior shoulder Superficial peroneal Fibular neck fracture, knee dislocation
Radial Distal humeral shaft fracture, anterior dislocation of shoulder Deep peroneal Fibular neck fracture, compartment syndrome
Axillary Anterior shoulder dislocation, Sciatic Posterior hip dislocation
Proximal humeral fracture Superior and inferior gluteal Acetabular fracture

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Apr 22, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 6 – Musculoskeletal Injury
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