ORTHOPEDIC AND SOFT TISSUE TRAUMA (also see Chapter 61 )

Musculoskeletal injuries with life- or limb-threatening potential or significant functional impairment are present in more than 50% of all hospitalized trauma patients. Lower extremity fractures are the leading cause of all trauma admissions. Musculoskeletal trauma usually requires a prolonged recovery phase to maximize functional and psychological outcome. Hospital costs from orthopedic trauma alone may be as high as $1.2 billion.^[180] A musculoskeletal trauma patient can be classified into one of three distinct types. The first type has an isolated closed musculoskeletal injury that requires surgical intervention on an elective basis. Trauma team involvement is optional. The second type has multiple fractures of major long bones and joints or significant injury potential. Management includes resuscitation by the trauma team and exclusion of life-threatening injuries before proceeding with early fracture stabilization. The third type involves multiple fractures of the major long bones, spinal column, and joints associated with multisystem injuries. These patients require skillful decision making by the trauma team, anesthesiologists, and intensivists over a protracted episode of care.

Dislocations of the hip are common after high-energy trauma and are frequently accompanied by fracture of the acetabulum. Whereas the fracture itself can be safely managed on a delayed basis, the dislocation is a medical emergency that must be promptly addressed if the patient is to have a good functional outcome. Failure to promptly diagnose and reduce a dislocated hip joint is a significant risk factor for avascular necrosis of the femoral head. Reduction typically requires a very deep level of sedation and may be facilitated by chemical paralysis of the patient. For this reason, the anesthesiologist is commonly involved.^[181] Although it is possible to reduce a dislocated hip in a spontaneously breathing patient sedated with fentanyl, midazolam, ketamine, propofol, or a combination of two or more agents, the anesthesiologist must remember that an acutely injured patient is at high risk for aspiration. Any patient who will be undergoing surgery in the near future (as for an open long bone fracture or an exploratory laparotomy) should be intubated at the time of reduction and maintained under a light general anesthetic until reaching the OR. Other patients who should be intubated even for uncomplicated reductions include those who are inebriated or uncooperative, hemodynamically unstable, or suffering from pulmonary dysfunction.

Fracture of the pelvic ring is caused by many of the same high-energy injuries that produce acetabular and long bone fractures. Whereas acetabular fractures are caused by impact on the knee, foot, or greater trochanter, with the energy transmitted to the acetabulum by the femur, pelvic fractures are the result of a direct blow to the pelvis. Unlike most acetabular fractures, fracture of the pelvis requires immediate recognition and management by the trauma team. Hemorrhage, even exsanguination, is common after major pelvic ring fracture and is a leading

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Other orthopedic injuries may be obvious or cryptic at the time of trauma center admission. One of the goals of the secondary survey is to assess the patient from head to toe for subjective pain and objective tenderness. Any indication of discomfort should be pursued with appropriate plain film radiography. Even so, closed orthopedic injury is a commonly missed diagnosis in trauma patients, particularly those with an altered level of consciousness or other, more serious injuries at the time of admission. When a bony injury is identified, a thorough neurovascular examination of the involved extremity should be conducted because of the potential for coexisting neurologic and vascular trauma. An angiogram may be needed to establish the patency of peripheral vessels and determine the need for urgent vascular surgery.

Limb salvage is possible in two thirds of patients with combined orthopedic and vascular injuries of the lower extremity, but a history of shock or crush injury with vascular compromise is an unfavorable prognostic sign.^[184] Open fractures should be pulse lavaged and débrided as soon as possible after injury to minimize the risk of infectious complications. If ongoing resuscitation or unstable TBI precludes the patient from early management in the OR, this procedure should be performed at the bedside.

Most orthopedic trauma patients will require analgesic therapy as soon as safely possible after injury. Small doses of narcotics should be titrated to control pain without clouding assessment of the neurologic examination or putting the patient at risk for respiratory depression. Patients with open fractures should receive a tetanus toxoid booster if immunizations are not up to date, as well as appropriate antibiotic prophylaxis. Patients with long bone fracture are at high risk for the formation of deep venous thrombosis because of both local trauma and edema in the involved extremity and enforced immobility until surgical fixation has occurred. These patients should receive prophylaxis with serial compression stockings and subcutaneous heparin. Fractionated low-molecular-weight heparin or warfarin should not be administered preoperatively unless a long delay before surgery is anticipated because these drugs may preclude the use of regional anesthetic techniques.

Anesthetic Technique

Most urgent orthopedic trauma cases will rely on general anesthesia because the patient is already intubated, multiple operations will be performed, the patient has altered mental status or a neurologic deficit, or the patient prefers general anesthesia. Surgical reasons to avoid regional anesthesia include uncertainty regarding the length of the proposed procedure and the need for intraoperative or postoperative assessment of peripheral nerve or spinal cord function. The trauma anesthesiologist should nonetheless offer regional anesthesia or adjunctive analgesia whenever it is an appropriate alternative. The advantages and disadvantages of regional and general anesthesia are summarized in Table 63-15 and Table 63-16 . For many orthopedic trauma cases, a combined approach will provide an optimal solution by incorporating the hemodynamic and analgesic benefits of a regional anesthetic with the flexibility and increased anxiolysis of a general anesthetic.

The choice of regional anesthetic depends on the site of surgery. For upper extremity surgery, the brachial plexus can be approached by the interscalene, subclavian, axillary, or infraclavicular route. Use of a nerve stimulator will help localize the injection of anesthetic in the vicinity of the desired nerves. An additional field block of the anterior and superior aspect of the upper part of the arm can help mitigate tourniquet pain if the procedure is protracted. For short procedures on the distal end of the upper extremity, intravenous regional anesthesia is a useful technique. For lower extremity injuries, options include spinal or epidural anesthesia, a combined spinal-epidural technique, three-in-one femoral and sciatic nerve block, popliteal and saphenous nerve block, and ankle block. Allowing adequate time for the block to take effect is essential to avoid losing the patient's confidence. Judicious use of sedation will facilitate both placement of the block and tolerance of the procedure.

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Conduct of anesthesia for an orthopedic trauma patient is not substantially different from the elective surgical setting. Anesthetic requirements should be comparable to those for similar patients in the nontrauma setting. A reduction in the patient's requirement for anesthesia (i.e., hypotension occurring at lower than expected anesthetic doses) should raise a strong suspicion of hypovolemia. Fluids and blood products should be administered and further diagnostic studies undertaken to establish the adequacy of resuscitation and the presence of any missed injuries. Controlled hypotension will decrease intraoperative bleeding and facilitate surgery in many orthopedic procedures, but it should be used only in patients without contraindications (underlying cardiovascular disease, SCI, TBI) who are known to be adequately resuscitated. MAP can be lowered 20 mm Hg below baseline by increasing anesthetic depth during critical periods of the operation.^[185] Narcotic requirements in trauma patients can vary widely, depending on the extent of injury and the individual history of substance use and abuse. If possible, allowing the patient to breathe spontaneously before the end of the procedure will provide a useful indicator of the patient's need for analgesics; respiratory rates greater than 20 per minute will generally indicate a need for further analgesia. Muscle relaxation may be required to facilitate intraoperative reduction of long bone fractures, but it may be allowed to resolve once the bone is aligned.

Intraoperative transesophageal echocardiography (TEE) has shown that most patients undergoing long bone fracture manipulation experience microembolism of fat and marrow.^[186] Most patients suffer no discernible clinical impact from this phenomenon, but some will experience a significant acute inflammatory response. Fat embolism syndrome is manifested as a triad of dyspnea, confusion, and petechiae and is probably triggered by immune reaction in the lungs. Increased free fatty acid levels in blood are associated with damage to the alveolar capillary membrane, leading to acute lung injury, and ARDS, causing hypoxia. Damage to cerebral capillaries causes edema, confusion, agitation, and even coma. Damaged capillaries in the skin are manifested as petechiae on the chest, upper extremities, and conjunctivae. Clinically apparent fat embolism syndrome is unusual and remains a diagnosis of exclusion.^[187] Treatment is usually supportive, with the use of epinephrine for acute hemodynamic management and continued mechanical ventilation with high levels of PEEP as needed to support oxygenation. The use of steroids to treat fat embolism syndrome is controversial. Therapies to reduce the incidence of fat embolism syndrome include early fixation of long bone fractures, placement of holes in the bone to allow venting of intramedullary contents, the use of reamed intramedullary nails, and limiting the use of cement. Methylmethacrylate cement helps in fixing prosthetic devices to bone. Polymerization of the cement is an exothermic reaction that causes intramedullary hypertension resulting in embolization of fat, bone marrow, and other debris. The cement itself may cause vasodilation and a decrease in systemic vascular resistance.^[188] The cement implantation syndrome may be manifested as hypoxia, hypotension, dysrhythmias, and pulmonary hypertension. Treatment is again supportive, with the use of increased FIO₂ , PEEP, and administration of crystalloids to support an adequate intravascular volume.