Challenging and Elusive Orthopedic Injuries: Diagnostic and Treatment Strategies
May 9, 1999
Challenging and Elusive Orthopedic Injuries: Diagnostic and Treatment Strategies for Optimizing Clinical Outcomes
Part II: Lower Extremity Injuries and Pediatric Fractures
Authors: William J. Brady, MD, Assistant Professor of Emergency Medicine and Internal Medicine, Program Director, Emergency Medicine Residency, Department of Emergency Medicine, University of Virginia School of Medicine, Charlottesville, VA; Gregory G. Degnan, MD, Assistant Professor of Orthopedic Surgery, Department of Orthopedic Surgery, University of Virginia School of Medicine, Charlottesville, VA; Leslie P. Buchanon, RN, MSN, ENP, Department of Emergency Medicine, University of Virginia Health System, Charlottesville, VA; Susan Schwartz, RN, MSN, ENP, Department of Emergency Medicine, University of Virginia Health System, Charlottesville, VA; Abhinav Chhabra, MD, Department of Orthopedic Surgery, University of Virginia School of Medicine, Charlottesville, VA.
Peer Reviewer: Dawn Demagone, MD, FAAEM, Assistant Program Director, Assistant Professor of Medicine, Division of Emergency Medicine, Temple University Hospital, Philadelphia, PA.
The second installment of this two-part article on difficult-to-diagnose and challenging orthopedic injuries focuses on lower extremity fractures, dislocations, and tendon disruptions, as well as pediatric injuries. The role of ancillary MRI and CT scanning techniques for evaluation of hip fractures and pediatric orthopedic trauma are outlined in detail.
Because orthopedic injuries involving the lower extremity—from talar and calcaneal fractures to tendon ruptures and occult epiphyseal disruptions in children—are associated with function-threatening complications, the approach to these anatomic regions must be systematic. When evaluating fractures of the lower foot, in particular, the emergency physician must maintain a high index of suspicion for associated tendon and soft-tissue injuries. Complicated fractures may be associated with compartment syndrome, a limb-compromising complication that requires prompt recognition and urgent management.
Because radiographic evaluation is key to optimal management, we have provided a supplement featuring x-rays that characterize difficult-to-identify fractures and which suggest views that will enhance recognition of elusive injuries.
—The Editor
Occult Hip Fracture in the Elderly
Acute fractures of the proximal femur are among the most common orthopedic injuries encountered by the emergency physician. From an anatomical perspective, these fractures include bony injury to the following structures: femoral head, neck, or proximal shaft; intertrochanteric or subtrochanteric regions; and isolated less or greater trochanteric areas. In the elderly patient who has fallen, femoral neck, intertrochanteric and subtrochanteric fractures are the most common bony hip injuries seen; the common mechanistic denominator in these injuries is weakened bone, most often osteoporosis. The elderly patient who sustains a fall and presents to the ED with severe hip pain usually does not present a diagnostic dilemma. Typically, the physical examination will reveal significant tenderness in the hip region with marked discomfort associated with any degree of movement of the affected extremity. Attempts at ambulation are difficult, if not impossible; if ambulation is possible, the gait is usually antalgic. The hip radiographs in these patients invariably demonstrate the suspected fracture.
In certain situations, however, the radiograph does not demonstrate a fracture (see Figure 1 in the special insert with this issue); in these cases, the emergency physician is then left with an osteoporotic patient who has experienced trauma and is unable to ambulate. The majority of these patients have inconsequential soft tissue injuries; however, the minority of elderly patients with this presentation, in fact, will have a fracture of the proximal femur that is not visualized on the radiograph—the so-called occult hip fracture. When this fracture is not detected, occult fracture has an even higher rate of morbidity and mortality; in particular, the orthopedic outcome may be compromised as a result of avascular necrosis. Numerous strategies have been recommended for evaluating these patients, including bed rest with repeat plain-film radiography in 7-10 days, and, if required, computed tomographic scanning, bone scan, and/or magnetic resonance imaging (MRI). Perhaps, the most appropriate diagnostic approach involves early application of the MRI (see Figure 2).1-3 This approach has been employed in many EDs with substantial success. A sound strategy includes use of MRI in the patient with a suggestive mechanism of injury and significant pain with hip movement and/or ambulation (i.e., a reasonably strong clinical impression of hip fracture coupled with a negative plain film). The time window during which the MRI will reliably demonstrate occult fracture is unknown, although many series suggest this injury may be identified as early as four hours after occurrence.1-3
Tibial Plateau Fractures
The medial and lateral tibial condyles form a plateau that transmits the weight of the body from the femoral condyles to the tibial shafts. Proximal tibial fractures include fractures above the tibial tuberosity. These fractures may be described as extra-articular, among them tibial spine, tubercle, and subcondylar fractures, or articular fractures, including the condylar injuries. Proximal tibial fractures may be divided into five categories on the basis of anatomy.
The normal forces that are applied to the tibial plateau include axial compression and rotation. Fractures occur when these forces exceed the strength of the bone. Automobile-pedestrian accidents in which the automobile bumper makes direct impact over the proximal tibia represent the most frequent mechanism of injury. A direct blow, such as a fall from a significant height, is responsible for approximately 20% of condylar fractures.4 The remaining 30% of the fractures result from a combination of axial compression and rotational strain. Fractures of the lateral tibial plateau are the result of an abduction force on the leg. Medial plateau fractures usually result from an adduction force applied to the lower leg. If the knee is in extension at the time of injury, the fracture tends to be anterior. Conversely, if the knee is flexed at the time of impact, the fractures tend to involve the posterior condyle.
Clinical Presentation. The patient with tibial plateau fracture will present with a history consistent with the aforementioned mechanism of injury, and will complain of pain and swelling; the knee may be slightly flexed. On inspection, there may be an abrasion, laceration, or area of ecchymosis indicating the point of impact. Typically, an effusion and decreased active range of motion are present. A varus or valgus deformity indicates a depressed fracture. Tibial plateau fractures frequently are associated with soft-tissue injuries to the collateral and cruciate ligaments, menisci, and/or surrounding neurovascular structures. One study evaluated 30 tibial plateau fractures and found a 56% rate of associated soft-tissue injuries, including involvement of the medial collateral ligaments (20%), the menisci (20%), the anterior cruciate ligaments (10%), the lateral collateral ligaments (3%), and the peroneal nerve (3%).4 The physical examination should include assessment of joint laxity. Distal neurovascular status should be assessed and documented.
Radiographs. Anteroposterior (AP), lateral, and oblique radiographic views of the knee usually are adequate for demonstrating a tibial plateau fracture. A specific film, the tibial plateau view, is helpful for assessing the degree of depression. Anatomically, the tibial plateau slopes from the anterior aspect superiorly to the posterior area inferiorly. Routine AP views may not detect this slope and, therefore, may not demonstrate some depression fractures. Plain film tomography, CT scanning, or MRI may be necessary to detect occult fractures or to assess the degree of depression of a fracture that is apparent on regular films. Multiple studies have compared MRI, CT, tomography, and plain-film radiography. One study found that MRI was more accurate than standard radiography in classification of the fracture, identification of occult fracture, and accurate measurement of the displacement and depression of fragments.5 MRI also provides reliable identification of associated intra- and periarticular soft-tissue injuries pre-operatively.5 Another trial investigated 30 patients with 31 tibial plateau fractures that were diagnosed with standard radiography, comparing tomography and MRI. MRI was found to be as effective as tomography in quantitating the amount of articular depression and was found to be more effective in determining the extent of comminution. Again, it was noted that MRI demonstrated associated ligamentous and meniscal injuries.6
Management. The therapeutic goal in managing tibial plateau fractures is precise reconstruction of the articular surfaces, stable fragment fixation allowing early motion, and repair of all concomitant lesions. The four most common treatment modalities include 1) compressive dressing; 2) closed reduction and casting; 3) skeletal traction; or 4) open reduction and internal fixation. Therapy depends upon on the type of fracture. A type I, nondisplaced fracture in an ambulatory patient with no associated ligamentous injuries may be managed with aspiration of the hemarthrosis, application of a compressive dressing, ice, and elevation for 48 hours. The patient will have to remain non-weight bearing until healing is complete. If after 48 hours x-rays remain unchanged, range of motion exercises and quadriceps exercises may be initiated. Casting is not recommended at the time of injury until 4-6 weeks because of the high incidence of knee stiffness. Early orthopedic consultation is advised.
Emergency management of Type II, local compression fractures depends upon the presence of associated ligamentous injuries, the location of the fracture, and the degree of depression. A depression of 8 mm or more requires operative intervention to elevate the fragment. Anterior or middle depression injuries are more ominous than posterior fractures. Conservative therapy of nondisplaced local compression fractures without ligamentous injuries includes aspiration of the hemarthrosis, compression dressing or posterior splint, and non-weight bearing for up to three weeks. Early orthopedic consultation is recommended.
Primary management of Type III, local compression, Type IV, total condylar depression, and Type VI, comminuted fractures includes ice, elevation, aspiration of hemarthrosis, and immobilization in posterior splint. The patient must remain non-weight bearing. Accurate radiographic assessment of the degree of displacement will determine therapy by the orthopedist. Type V split fractures will need immediate consultation, since open reduction with internal fixation is the recommended therapy.
Complications. Tibial plateau fractures are prone to the development of several serious complications. Because loss of full range of motion of the knee may follow prolonged immobilization, the importance of early non-weight bearing range of motion and quadriceps exercises cannot be overemphasized. Angular deformity of the knee may develop in the first several weeks, even with nondisplaced fractures. Early orthopedic referral and follow-up are essential. Persistent subluxation or instability may complicate these injuries if there is ligamentous damage. Post-operative infection is a risk to open reduction and internal fixation or hemarthrosis.
Degenerative arthritis is a potential, long-term complication of tibial plateau fractures. Secondary osteoarthritis after tibial plateau fracture is found in approximately one-half of patients 10 years after the initial injury.7 Narrowing of the joint space was noted during the first seven years after injury, usually in the same compartment as the fracture. The incidence increases with age of the patient at the time of the injury. Removal of the meniscus resulted in secondary degeneration in 74% of the patients. When the meniscus was intact or repaired, the percentage of degenerative changes decreased to 37%.7 Normal or slight valgus alignment of the tibial plateau with an intact meniscus protected best against degenerative disease. However, medial or lateral tilt of the plateau after removal of a meniscus was complicated by osteoarthritis in many cases. Associated ligamentous injuries and postoperative infection increased the incidence of secondary degeneration. Neurovascular complications usually are the result of compartment syndromes.7,8 The complication of compartment syndrome after tibial plateau fracture is relatively rare because of the dissipation of tissue pressures into the knee joint compartments.
Knee Extensor Mechanism Disruptions
The extensor mechanism disruptions involving the knee include rupture of the quadriceps tendon, patellar fracture, patellar tendon rupture, and tendon avulsion at the tibial tubercle. The most commonly encountered disruption involves rupture of the patellar tendon. (See Figure 3.) Extensor mechanism disruption generally occurs as the result of the quadriceps muscle suddenly contracting forcefully against a slightly flexed knee; biomechanical study has shown that when the knee is slightly flexed, the forces across the patellar tendon are maximal. Direct trauma to either the patella or the proximal tibia may also result in extensor mechanism disruption, which usually involves a patellar fracture or avulsion of the patellar tendon. Misdiagnosis by the primary care provider has been reported to be as high as 38%.9 Accurate early diagnosis is essential to ensure the best outcome, which requires early surgical repair and intensive physical therapy.
Quadriceps tendon rupture is more common in patients with systemic disease, such as chronic renal failure, gout, hyperparathyroidism, diabetes, and obesity; patients with degenerative arthritic changes in the knee also are susceptible. Patellar tendon injuries in this patient group are less common; in general, individuals with this injury tend to be younger and less likely to have degenerative disease or systemic illness. Bilateral patellar tendon rupture has been reported and is associated with systemic lupus erythematosus and rheumatoid arthritis. Extensor mechanism disruption has been reported as an unusual complication of Paget’s disease; the patellar tendon usually is avulsed from the tibial tubercle in the region of pagetic bone.9 In other cases, rupture of the tendon occurs through a pathologic area of the tendon; several studies have implicated steroid injections and microscopic damage to the tendon’s vascular supply as a cause of failure.9
The clinical presentation of extensor mechanism disruption generally includes complaints of acute onset of knee pain accompanied by loss of function. The history includes either stumbling or jumping followed by sudden buckling of the knee and extreme pain. The patient usually gives a history characterized by forceful axial loading on a partially flexed knee; the inability to extend the knee results in loss of function. Furthermore, a careful medical history is essential to alert the examiner to associated systemic illnesses.
Physical examination may reveal a palpable defect in the quadriceps or patellar tendon; accordingly, the position of the patella should be assessed. Quadriceps tendon ruptures will present with inferior displacement of the patella (patella baja), proximal ecchymosis, and swelling. In contrast, proximal patellar displacement (patella alta), inferior pole tenderness, and swelling indicate patellar tendon rupture. Evaluation of range of motion will reveal markedly depressed active extension at the knee, inability to maintain passive extension against gravity, or complete loss of knee extension. Patients with partial ruptures may have active extension, but it will be markedly weakened. Hematoma or hemarthrosis may mask these clinical signs. In most cases, the diagnosis is made on the basis of the patient’s inability to extend the knee in the setting of an appropriate mechanism of injury.
Radiographs. Radiographic findings in patients with quadriceps tendon rupture include inferior patellar displacement (patella baja), superior pole boney avulsion fragment, and degenerative spurring of the patella seen on the tangential view (tooth sign). Complete disruption of the patellar tendon is suggested by superior displacement of the patella (see Figure 4) and inferior boney avulsion fragment. Comparison views may be necessary for diagnosing subtle patellar displacement. In cases involving bony injury, either a patellar fracture or an avulsed bone fragment will be seen on the radiograph. In many cases, the radiograph may be entirely normal; this finding should not dissuade the clinician from the diagnosis of patellar tendon rupture.
Additional radiographic imaging may be required, usually after referral to the orthopedic surgeon. The quadriceps and patellar tendons are easily visualized using MRI. Partial tears and tendinosis may be difficult to diagnose, but complete tears are easily visualized. Patellar fractures, bone bruises, and avulsion of the tibial tubercle are revealed as changes in marrow signal intensity. MRI is also extremely useful for identifying associated meniscal tears and chondromalacia patella. Ultrasound and CT have also been used to evaluate continuity of the extensor mechanism.
Accurate diagnosis of partial or complete patellar tendon ruptures, avulsion fractures of the patella or tibial tubercle, and complete quadriceps tendon tears is essential because optimal outcomes are obtained with early surgical repair. The primary treatment issues for the emergency physician include accurate diagnosis and timely orthopedic referral. Orthopedic consultation should be initiated at the time of injury or within 24 hours of presentation. Knee immobilization with crutch walking should be advised until orthopedic follow-up is accomplished. Definitive repair usually involves surgery. Delay in treating a quadriceps tendon tear for 4-6 weeks may result in the tendon being difficult to mobilize. Patients with patellar tendon ruptures that have gone undetected for more than two weeks may develop significant proximal retraction of the patella, with quadriceps contracture and adhesion. Most surgical repair techniques are followed by immobilization in a long leg cast in extension for 4-6 weeks, with partial weight bearing using crutches. Intensive physical therapy is prescribed, beginning with active flexion and passive extension exercises. Strengthening exercises are advanced as knee flexion returns. Patients can return to sporting activities in 4-6 months, when knee flexion is at least 120° and strength deficits are less than 10%.
Achilles Tendon Rupture
Emergency physicians are often the first to evaluate Achilles tendon injuries. The diagnosis of Achilles tendon rupture is missed in about 25% of cases.10 An overlooked rupture can lead to discernible loss of long-term function. Achilles tendon is the most commonly ruptured tendon, accounting for 40% of all surgically repaired tendon ruptures.10 A Scandinavian study of 111 closed Achilles tendon ruptures from 1979 through 1994 demonstrated a mean age of 40, and a division by sex of 85% men to 17% women. Seventy percent of the patients were recreational athletes, 18% competitive athletes, and 12% practiced no sport.11
Achilles tendon rupture occurs when stress is applied to a previously contracted muscle/tendon. A rapid push off with the knee extended or a sudden unexpected dorsiflexion have been suggested as mechanisms of injury. These injuries occur most frequently (81%) while playing sports, usually during an activity requiring sudden acceleration or jumping.11 Rarely does the rupture occur from a direct blow to the tendon. Typically, the injury occurs to middle aged men who are weekend athletes. The tendon most often ruptures 2-6 cm proximal to the calcaneus, the area of the tendon with minimal blood supply.12 Although patients may describe symptoms related to Achilles tendinitis prior to the injury, this prodromal complaint is generally not the case. Histologically, however, virtually all patients with acute Achilles tendon rupture have preexisting degenerative changes of their tendon; specifically, these include hypoxic, mucoid, lipomatous, and calcific changes.
The history of the injury frequently is pathognomonic. Typically, patients describe a sudden, audible bang or pop, with immediate burning or searing pain in the posterior ankle. Patients describe a sensation of having been shot or kicked in the heel and often turn around to search for an assailant. Most patients seek immediate medical care since they are unable to walk normally on the affected foot. The initial sharp pain is replaced by a dull ache and stiffness in the ankle. Physical examination of the ankle should include active range of motion, palpation of the length of the tendon from the gastrocnemius muscle to the calcaneus, and the Thompson’s squeeze test. The range of motion may or may not reveal an inability to plantar flex the foot, as the posterior tibialis and intact toe flexors may compensate for the completely ruptured tendon. A palpable defect in the tendon and tenderness at the site of rupture are characteristic of a ruptured Achilles tendon. The most reliable sign of a completely ruptured tendon is a positive Thompson’s squeeze test. (See Figure 5.) The patient is placed with the knees flexed to 90°—a squeeze of the calf muscles will produce passive plantar flexion of the foot in the unaffected tendon. A positive, or abnormal, Thompson’s squeeze test is an absence of passive plantar flexion.
Most often, the diagnosis of a ruptured Achilles tendon usually is made based on the history and physical examination. Radiographic examination is a simple and relatively inexpensive adjunct to diagnosis when the physical examination is equivocal.13 A lateral x-ray view will help identify Kager’s Triangle. A normal Achilles tendon is demonstrated by a clearly perceptible Kager’s triangle, with easily identified smooth edges. Patients suffering from ruptured Achilles tendons demonstrate a smaller, less transparent, fuzzy triangle.12 The utility of MRI in the ED is very limited; however, it does provide a very clear picture of the Achilles tendon and may be employed in difficult cases either in the ED or in the orthopedic office at follow-up.
Management. In the acute setting, at time of initial presentation, two approaches for management of a ruptured Achilles tendon are described in the orthopedic literature.14,15 Lea and Smith14,15 have been advocates for non-operative management with a cast for eight weeks. The patient is initially placed in a posterior splint with the ankle placed in gravity equines (not forced equines). This conservative method of management, however, is complicated by a recurrent rupture in 10-35% of cases. The second option for initial management is surgical repair, using one of many techniques. Surgical repairs are complicated by a much lower re-rupture rate (i.e., less than 6%). Proponents of surgical repair argue that the decreased risk of re-rupture, coupled with a stronger tendon outweighs the risks associated with surgery. Nonetheless, for the emergency physician, either orthopedic consultation in the ED or very close orthopedic follow-up within several days of presentation is required in all suspected cases. Although the patient faces a prolonged convalescence regardless of therapy, the correct initial diagnosis and appropriate management by the emergency physician will have a major impact on the long-term recovery.
Posterior Malleolar (Ankle) Fracture
Isolated posterior malleolus fractures, although rare, have been reported as "frequently overlooked radiographically."16 Fractures of the posterior malleolus, however, are most often seen in association with lateral and/or medial malleolar fractures of the ankle. Avulsion fractures of the posterior tibial tubercle are seen in association with injuries of the posterior tibio-fibular ligament. Fractures of this kind do not produce major instability of the ankle and, therefore, have minimal clinical significance. Fractures of the posterior process of the tibia (posterior lip), however, represent significant injuries. These fractures, through the articular surface, frequently lead to subluxation of the talus. According to the Lauge-Hansen classification of ankle fractures, avulsions or ruptures of the posterior tibio-fibular ligament occur when an eversion force is applied to a supinated ankle. Posterior lip fractures of the tibia are most often seen when the eversion force is applied to a pronated ankle through axial force. These serious fractures, however, may be associated with any mechanism of injury producing a malleolar fracture. Other factors that predispose to a posterior lip fracture include obesity and osteoporosis.
Presentation. Patients with posterior malleolus fractures usually give a history describing a forced ankle twist. Isolated, posterior malleolus fractures most often present with swelling, tenderness, and ecchymosis around the Achilles tendon. Posterior malleolus fractures associated with medial and/or lateral malleolar fractures present with significant, generalized soft tissue swelling and pain and, in some cases, with talar dislocations. Initially, standard radiographs of the ankle including AP, lateral, and mortise views are required for accurate assessment. Often, posterior malleolar fractures are seen only as double densities that are superimposed on the tibial metaphysis; as a result, they may be missed. Patients who present with a high degree of suspicion should have a CT scan performed that can provide explicit imaging of the size, location, and displacement of fractures.
Avulsions of the posterior tibio-fibular ligament (which does not contribute to the stability of the ankle) do not require fixation. Initial management consists of an ankle immobilization device and other symptom-based therapy. Conversely, fractures of the posterior lip of the tibia frequently are associated with significant instability; the talus may be dislocated posteriorly and, therefore, cannot be maintained in reduction. Dorsiflexion of the foot aggravates the inclination to dislocate. Patients with posterior malleolus fractures should be placed in a Robert Jones dressing—dorsiflexion should be avoided—to reduce soft tissue swelling. If more than 25-30% of the joint surface is involved, most authors agree that the fragment should undergo open fixation in order to stabilize the ankle.17
Calcaneal and Talar Fractures
The talus and the calcaneus make up the hindfoot; a major structural determinant of normal gait. In combination, the tibiotalar (ankle joint) and talocalcaneal (subtalar joint) comprise a universal joint. The tibiotalar joint provides for flexion and extension, whereas the subtalar joint is responsible for up to 65° of inversion/eversion movements. This universal joint provides a "shock absorber" effect for the hindfoot during normal gait, as well as the ability to ambulate on uneven surfaces (i.e., the off-center heel strike). Loss of universal joint function will cause the talus to bind in the ankle mortise, increasing sheer stress and decreasing efficiency of gait. As a result, fractures of the hindfoot are common and are associated with significant morbidity if missed or treated inappropriately. Avascular necrosis of the talus or subtalar arthrosis are potentially devastating sequelae of these fractures, which can be prevented with early diagnosis and proper treatment. Unfortunately, assessment can be difficult, inasmuch as radiographs of this area can be difficult to interpret.
Stress Fractures. Stress fractures of the foot were once encountered almost exclusively in military recruits. However, recent interest in physical fitness and running has made this fracture much more common in the general population. Running and athletic activity are not the only risk factors for stress fracture. Any new mechanical stress applied to the foot can produce this injury. Stress fractures have even been reported in patients following bunionectomy. Accordingly, any patient with foot pain and a recent history of increased or altered activity should be considered a possible candidate for stress fracture.
Although the most common sites for stress fracture of the foot are the second metatarsal and the calcaneus, any bone can be involved. Interestingly, calcaneal stress fractures have been noted to be bilateral in approximately one-quarter of all cases.18 Moreover, it is not uncommon to have multiple sites of stress fracture in the same foot. The typical underlying mechanism of injury is excessive, repetitive stress applied to a bone that does not have sufficient structural strength to withstand such stress. Under such circumstances, especially if the stress is applied long enough, the bone will fatigue and break. Bone resists fatigue fracture by remodeling—strength is enhanced by adding trabeculae along lines of stress. This process, however, is slow and requires up to two weeks to resorb the old trabeculae in vulnerable areas. As might be expected, if excessive stress is applied before the new trabeculae form, a fracture occurs. Since the calcaneus is primarily cancellous bone, the typical result is a compression fracture at the junction of the body and the tuberosity.
In the initial stages of this condition, the patient will develop mild to moderate pain accompanied by localized swelling. It is unusual for the physician to see the patient at this stage, since the individual usually will try to work through the pain. At this point, the physical findings are nonspecific. With careful examination, however, a discreet area of point tenderness can be localized. Plain x-ray will be normal at this stage. Bone scan, however, the diagnostic study of choice, will demonstrate increased uptake at the fracture site as early as two days after the onset of symptoms.18 Treatment during the early stages consists of protecting the extremity from stress until the symptoms resolve, which usually requires about 1-3 weeks. Protection against future injury can be achieved by eliminating stressful activity, putting the patient on crutches, or application of a walking cast. Orthopedic or primary care follow-up is recommended. When symptoms resolve, the patient may be allowed to gradually return to his or her normal activities.
Patients who present more than two weeks after the onset of symptoms usually will have more definitive physical and radiographic findings. Swelling and tenderness are invariably present. Radiographs will usually show bone resorption, a transverse fracture line, or new periosteal bone formation. (See Figure 6.) ED treatment at this stage consists of rest to the foot to facilitate healing of the fracture, a posterior splint and crutch walking, and prompt orthopedic outpatient follow-up. Some authors advocate immobilization in a non-weight-bearing cast. Generally, however, immobilization in a weight-bearing cast is sufficient. Protection should continue until the fracture is non-tender, which usually requires about 4-6 weeks. The patient may then begin gradual, progressive return to normal activities.
Talar Neck Fractures. The talus is one of the most important bones in the foot because it both supports and distributes the body’s weight. It permits motion between the tibia and the foot, and is the pivot point for tibiotalar and subtalar motion. The talus is the second most commonly fractured tarsal bone. These fractures are important because of the potential loss of function associated with talar injuries and because of poor blood supply to this bone. Three-fifths of the bone is covered with articular cartilage, and fractures through the neck have a high incidence of avascular necrosis. The most common mechanism of injury producing talar neck fracture is hyperdorsiflexion of the foot; rarely, however, a direct blow to the dorsum of the foot may produce a neck fracture. The typical sequence of injury usually occurs as follows: 1) with hyperdorsiflexion of the foot, the posterior capsular ligaments of the subtalar joint rupture; 2) the neck of the talus makes an impact against the anterior edge of the distal tibia; and 3) a fracture line develops at the neck of the talus.
The history usually involves one of a severe, high-energy injury in which the foot is driven into dorsiflexion, as might occur in a motor vehicle accident in which the foot is driven against the brake pedal or in a fall from a great height. The patient will complain of severe pain in the foot and ankle and, usually, will not be able to bear weight. They will note immediate and significant swelling. On examination, the foot and ankle will be grossly swollen, with loss of normal contours of the ankle and hindfoot. The foot and ankle should be assessed for open wounds; tented skin with ischemic appearance should be noted, and neurovascular integrity evaluated. The examining physician should identify associated injuries, which are common because of the high-energy mechanism; in fact, associated lower-extremity injuries have been reported in approximately two-thirds of talar neck fractures.19 All structures should be palpated and assessed for tenderness or swelling. All suspected talus fractures should be evaluated with AP, lateral, and mortise views of the ankle, as well as AP and lateral films of the foot. The AP and mortise views of the ankle will demonstrate alignment of the talus in the mortise and will identify associated ankle fractures. The lateral x-ray of the ankle and foot is used to demonstrate a fracture line through the talar neck and to evaluate the alignment of the subtalar joint.
In the ED, the key to optimizing outcomes in these injuries is maintaining a high index of suspicion, which permits early recognition and treatment. Immediate orthopedic consultation usually is indicated since definitive treatment involves early, open reduction and internal fixation. When an orthopedist is not immediately available, an attempt at closed reduction should be made. Closed reduction is accomplished by manipulating the foot so that it is realigned with the body fragment. Sedation and/or ankle block should be administered as gentle traction is applied. While traction is initiated, the foot is plantar flexed to bring the head fragment in line with the body, and AP and lateral x-rays should be obtained. (See Figure 7.) If reduction is achieved the foot should be splinted, not acutely casted, in plantar flexion. Urgent consultation should be arranged.
Fractures of the Calcaneus. The calcaneus is the most commonly fractured tarsal bone. Intra-articular fractures account for 75% of calcaneus fractures. Almost always, this injury is the result of from a fall from a significant height. Typically, the patient lands on the heels, with the entire weight of the body absorbed by the calcaneus, a primarily cancellous bone lacking cortical strength. Consequently, the fall does not have to be from a great height. The severity of the injury depends more on the exact location of the point of impact than on the height of the fall. It is critical to appreciate that these injuries have a significant potential for producing soft tissue complications if not recognized and treated properly in the acute setting. In addition, the ED physician must be aware of the high incidence of associated spine injuries.
Clinical Presentation. The patient with a calcaneus fracture will present with heel pain and swelling. Unlike those with a talar neck fracture, these patients may be able to bear weight despite considerable pain. It should be stressed that this injury is associated with other lower extremity injuries in 70% of cases and spine fractures in 10%; moreover, these other injuries can be painful enough to overshadow the foot injury and the patient may not even complain of significant heel pain. Accordingly, all patients who sustain a fall from a height should have a comprehensive examination directed at the heel to the thoracic spine. Calcaneus fractures present with tenderness, swelling, and ecchymosis of tissues surrounding the calcaneus; ecchymosis extending onto the arch of the foot is felt to be pathognomonic of a calcaneus fracture. The normal contour of the heel is lost and the heel appears widened and shortened. (See Figure 8.) Open fractures are common and the skin should be carefully examined for small puncture wounds. Finally, fracture blisters can develop very quickly and may affect the course of treatment.
Radiography. The basic radiographic series for a suspected calcaneus fracture includes AP, lateral, and Harris axial views of the foot. The lateral view will demonstrate most intra-articular fractures. Bohlers’ angle, measured on the lateral view, is used to assess the degree of compression of the calcaneus; it also is useful in detecting a radiographically occult calcaneal compression fracture, as well as in determining the congruity of the posterior facet of the subtalar joint. The angle itself is obtained by drawing two lines—one from the posterior tuberosity to the apex of the posterior facet, and the other from the apex of the posterior facet to the apex of the anterior process. (See Figure 9.) Bohlers’ angle may vary from 20 to 40°; a compression fracture is suggested with an angle less than 20°. (See Figure 10.) If a fracture is identified, a lateral x-ray of the opposite foot is necessary in order to compare the angles. The axial view of the foot demonstrates the amount of widening of the heel and is critical for guiding definitive treatment. The AP of the foot will reveal extension of the fracture into the calcaneocuboid joint or associated subluxation of the talonavicular joint.
The acute ED treatment of these fractures requires careful management of the soft tissues. Soft-tissue swelling and fracture blisters frequently accompany this injury during the first hours after injury. Immediate application of a bulky, compressive dressing with a posterior splint, combined with elevation and ice application, can prevent fracture blisters and skin sloughing; surgical intervention may be required.
Lisfranc Fracture/Dislocation
The articulation between the tarsal and metatarsal bones in the foot is named after the French physician, Jacques Lisfranc, a field surgeon in Napoleon’s army who first described amputations through this joint. Injuries to this anatomic region result from falls and motor vehicle or industrial accidents, and range from mild sprains to severe dislocations, as well as fracture/dislocations. Historically, Lisfranc injuries were thought to be rare, accounting for less than 1% of all orthopedic trauma; the overall incidence, however, is increasing and these fractures are more common than initially recognized.20 The complex bony and ligamentous anatomy of this joint and the multiple patterns and mechanisms of injury make radiographic interpretation challenging and the diagnosis difficult. In fact, the diagnosis is missed on initial presentation to the emergency department in about 20% of cases.20-23 Failure of diagnosis, misdiagnosis, or inappropriate treatment is associated with an increased risk for chronic disability.20 As a result, emergency physicians should be familiar with the presentation of Lisfranc injuries, and recognize that early diagnosis and timely orthopedic referral are essential for optimal treatment and outcome.
Lisfranc injuries are caused by either direct or indirect trauma. Direct or crush injuries to the dorsum of the foot are rare and may be complicated by contamination, vascular compromise, or compartment syndrome.20 Displacement of the metatarsal bases may occur in either the plantar or dorsal direction depending on the direction of force at the time of injury. Indirect forces are responsible for the largest group of injuries, which result from either a rotational force applied to the forefoot with a fixed hindfoot or axial loading on a plantar flexed, fixed foot. The longitudinal force results in metatarsal dislocation dorsally at the site of least resistance, while the rotational force causes dislocation medially or laterally. Inasmuch as significant energy is required to produce dislocation, these injuries frequently are associated with multiple fractures and significant soft-tissue injury.24 Common causes of indirect trauma include falls from a height, motor vehicle or motorcycle accidents, equestrian accidents, and athletic injuries.
Lisfranc injuries range from mild, undetectable subluxations to obvious fracture/dislocations. The clinical presentations are as varied as the patterns of injury. Consequently, the emergency physician should always maintain a high index of suspicion when evaluating an injured foot. Patients with a significant tarsometatarsal injury, generally present with complaints of midfoot pain, swelling, and difficulty bearing weight. In mild injuries, patients may be able to bear weight acutely and may be surprisingly active despite the pain. Tenderness along the Lisfranc joint is common and passive pronation with abduction of the forefoot with the hindfoot held fixed elicits pain; this maneuver is specific for tarsometatarsal injuries.24 The foot may appear normal or markedly deformed, depending on the severity of the injury. However, significant swelling of the foot may mask a deformity. If the mechanism of injury is severe or deformity is obvious, manipulation of the foot should be kept to a minimum to prevent further displacement.
A broadened foot, shortening in the anteroposterior plane, or a pathologic range of motion suggest severe fracture dislocation.22 One study reported the potential for injury to the terminal branch of the dorsalis pedis artery as it passes to the plantar surface of the foot between the first and second metatarsal.22 Vascular compromise at this level rarely results in ischemic necrosis of the foot, but severe fracture dislocations can damage vessels or cause vascular spasm at the level of the ankle (posterior tibial artery). Serial vascular exams are important if this injury is suspected. Tense swelling of the foot with diminished pulses suggests compartment syndrome; in these cases, immediate surgical intervention is necessary to save the extremity.20,24 In a multiply injured, unconscious patient, the injury is easily missed because more life-threatening issues preclude full evaluation of the extremities. After the patient’s condition has improved, stability of the tarsometatarsal joint should be evaluated.
Radiography. Proper radiographic evaluation of the foot is essential for the diagnosis of Lisfranc injuries. The tarsometatarsal trauma series should include accurate radiographs of three planes of the injured foot—anteroposterior, lateral, and oblique views. Comparison radiographs of the contralateral foot may be helpful in detecting subtle injuries. Major fracture/dislocations are easily recognized and are rarely missed. Sprain injuries without dislocation, however, are difficult to diagnose radiographically even though physical examination findings are highly suggestive of tarsometatarsal involvement. Roentgenograms of the tarsometatarsal joint can be difficult to interpret because of the overlapping bony articulations. Lisfranc injuries will not be missed if the clinician is familiar with the consistent anatomical relationships of the normal foot. The second metatarsal base should always be carefully evaluated for fracture, avulsions, and displacement. On AP and oblique radiographs, the medial border of the second metatarsal base and the middle cuneiform and the medial border of the fourth metatarsal base and cuboid should form a straight, unbroken line.20 Any disruption of these lines or fracture fragments around the base of the second metatarsal or along the lateral border of the cuboid indicates significant tarsometatarsal injury. (See Figure 11.) Other normal findings include a straight line formed by the lateral border of the base of the third metatarsal and lateral border of the lateral cuneiform. On the lateral film, a metatarsal shaft should never be more dorsal than its respective tarsal bone.21 (See Figure 12.) A fracture of the cuboid, cuneiforms, navicular, or metatarsal shafts is suggestive of disarticulation of the tarsometatarsal joint. In minor subluxation injuries, the key to diagnosis is the mortise configuration of the second metatarsal. Separation between the base of the first and second metatarsal or between the medial and middle cuneiforms is strongly suggestive of subluxation.22,24 Widening can also occur between the second and third metatarsal or middle and lateral cuneiforms. A minor displacement of the three lateral metatarsal bones may be missed on AP and lateral films but should be obvious on 30° oblique views.22
Definitive treatment of these fractures involves surgical intervention. The ED physician should suspect the diagnosis, confirm the injury radiographically, and recognize that compartment syndrome may accompany this fracture. If orthopedic consultation is not immediately available, the emergency physician should attempt closed reduction by hanging the foot by the toes using finger traps. If reduced, a bulky compressive dressing should be applied with a posterior splint. These injuries warrant acute orthopedic evaluation.
Compartment Syndrome
Compartment syndrome is a serious life- and limb-threatening complication of extremity trauma. Fracture, crush injury, burn, and arterial injuries can result in increased tissue pressure within a closed compartmental space.25 Compartment syndrome develops when there is increased pressure in a limited space, such as muscle compartments bound by dense fascial sheaths. Compartments in the arm and leg are most vulnerable to this syndrome. The upper arm contains anterior (the biceps-brachialis muscle and the radial, ulnar, and median nerves) and posterior (the triceps muscle) compartments. The forearm has a volar and dorsal compartment; the volar compartment contains the wrist and finger flexors, while the dorsal compartment holds the wrist and finger extensors. In the lower extremity, there are three gluteal compartments, anterior and posterior compartments in the thigh, and four compartments in the lower leg. The anterior compartment of the lower leg is most frequently involved in this syndrome and contains the tibialis muscle and the extensors of the toes.
The pathophysiology of compartment syndrome involves local hydrostatic and osmotic pressure conditions within the myofascial compartment. When the intracompartmental pressure increases above a specific level due to such factors as hemorrhage, inflammatory fluid, or external compression on the myofascial compartment, perfusion to the compartment is impaired, resulting in disruption of skeletal muscle metabolic processes. Cell wall membrane integrity is compromised, leading to cytolysis with the release of osmotically active cellular contents into the compartment. Each millimole of osmotically active particle per kilogram of tissue water adds 19.5 mmHg to the effective pressure gradient, thus attracting additional fluid from plasma into the interstitial space.26 The net effect is increased intracompartmental pressure and further disruption of perfusion to the closed space of the myofascial compartment, as well as to distal structures of that vascular distribution, which can ultimately lead to a compromise of the circulation and/or nerve conduction as well as irreversible muscle injury, contractions, loss of limb, myoglobinuria, renal failure, and, occasionally, death.27
Compartment syndromes are caused by a number of conditions that either decrease the compartment size or increase the compartment contents. Compartment size may be reduced by constrictive dressing or casts, pneumatic pressure garments, prolonged compression of the compartment by patient immobility, closure of fascial defects, or thermal injuries (either burns or frostbite). A volume increase can result from fractures, soft-tissue injuries, and prolonged immobilization with limb compression, vessel lacerations, exertion, edema, hemorrhage, or hematoma. The most common cause of compartment syndrome is fracture of the tibia. Other common fractures associated with compartment syndrome are supracondylar fractures of the humerus, humoral shaft, and forearm fractures. Crush injuries to the hand or foot with or without associated fractures are a predisposing factor. The potential for compartment syndrome should also be considered with multiple metacarpal or metatarsal fractures, Lisfranc fractures/dislocations, and calcaneal fractures.
Clinical Presentation. A hallmark element of the history in a patient presenting with compartment syndrome is pain disproportionate to the mechanism of injury. Patients may also complain of a change in sensation, weakness, and pain with any movement of the involved extremity, as well as tightness and swelling of the involved area. Clinical signs of compartment syndrome can easily be remembered by using the mnemonic of the five P’s: pain, paresthesia, paresis, pulses, and pressure. Pain, especially disproportionate pain, is often the earliest sign, but loss of normal neurological sensation is the most reliable sign. Decrease or loss of two-point discrimination is also an early and reliable finding of compartment syndrome. Skin and subcutaneous tissues are better able to survive hypoxia than are skeletal muscle and peripheral nerves. Careful serial sensory and motor examinations are essential. Clinical findings also include pain with passive range of motion; a palpable, tense compartment; shiny, erythematous skin overlying the involved compartment (described as a "woody" feeling); and excessive swelling. A thready or diminished pulse is not a very reliable early sign. Intra-compartmental tissue pressure is usually lower than arterial blood pressure, making peripheral pulses and capillary refill poor indicators of blood flow within the compartment. Patients with a very low diastolic blood pressure are more susceptible to compartment syndrome.
Diagnosis. Pulse oximetry has been advocated as a simple, noninvasive indicator of vascular compromise. One study investigated the reproducibility of pulse oximetry and the effect on arterial hemoglobin saturation of raising intracompartmental pressure by compression bandaging. At clinically significant pressures, the test had a sensitivity of approximately 40%. With a greater then 50% risk of false negatives, pulse oximetry is not recommended for detection of elevated intracompartmental pressure.28
The diagnosis of compartment syndrome is based on direct determination of the intracompartmental pressure. Normal tissue pressure ranges between zero and 10 mmHg. Capillary blood flow within the compartment may be compromised at pressures greater than 20 mmHg. Muscle and nerve fibers are at risk for ischemic necrosis at pressures greater than 30 to 40 mmHg. Tissues within the compartment may become ischemic and necrotic if pressure is not promptly reduced. The direct measurement of compartment pressures will definitively rule-in or rule-out the diagnosis.
Several techniques are available for intracompartmental pressure determination; each has its advantages and disadvantages. They include the needle technique, wick catheter, and the slit catheter. The needle technique can be performed with items that are readily available in the ED. An 18-gauge needle is attached to an intravenous extension tube and then to a stopcock. Approximately half the tubing is filled with sterile saline; air should not be allowed into the tubing. A second intravenous extension tube is attached to the four-way stopcock with the opposite end attached to the blood pressure manometer. The needle is then placed in the compartment and the apparatus kept at the level of the needle. The stopcock is then turned so that it is open in the direction of the intravenous tubing on either side of a syringe. The syringe filled with air is slowly compressed, causing air to move into both extension tubes. The meniscus created by the saline in the extension tube attached to the 18-gauge needle is watched carefully for any movement. As soon as movement occurs in the fluid column, the compartment pressure is read from the blood pressure manometer. This technique, while simple to perform with minimal equipment, may be inaccurate.
The wick catheter provides more accurate readings, but can become coagulated at the catheter tip and leave material behind in the wound. The wick catheter and slit catheter methods can only measure one compartment site per catheter and require cumbersome, specialized accessory equipment. Portable, hand-held tissue pressure monitoring systems are available and are widely used. These systems are easy to assemble and apply in the ED; multiple uses are possible per unit, making the system cost effective. Their accuracy has been found to be equivalent to the slit catheter and superior to the needle technique.
Regardless of the method used, the skin should be prepped with an antiseptic solution and infiltrated with local anesthesia at the prospective site. Only the subcutaneous tissue should be infiltrated. Intramuscular injection may artificially elevate compartment pressure. To assure that the needle is in the compartment, external pressure can be applied through the surrounding skin to the muscle compartment below. The muscle group may also be passively stretched to transiently increase compartment pressure. The site of pressure measurement is important. In a study of 25 patients with closed tibial fractures, failure to measure tissue pressure within a few centimeters of the zone of peak pressure can result in underestimation of the maximum compartment pressure. Measurements should be taken in both the anterior and deep posterior compartments at the level of the fracture as well as at locations proximal and distal to the zone of the fracture to determine the locations of highest tissue pressure in a lower extremity.
Treatment. The goal of treatment of compartment syndrome is to decrease tissue pressure, restore blood flow, and minimize tissue damage and related functional loss. External pressure from casts or dressings should be removed immediately. It has been shown that if a cast is bivalved, the compartment pressures may decrease as much as 55%, and if a cast is completely removed, the pressure may decrease as much as 85%. The affected limb should be elevated to the level of the heart to promote arterial blood flow and not decrease venous return. Elevation above the heart can result in decreased perfusion. Ice is contraindicated because it may compromise the microcirculation. Steroids and vasodilating agents have not been shown to be of benefit.
Acute compartment syndrome is a surgical emergency. Fasciotomy is definitive therapy and should be performed as soon as possible. Delays of more than 24 hours can have devastating consequences, including significant muscle mass damage resulting in myoglobinuria, renal failure, metabolic acidosis, hyperkalemia, and, ultimately, contracture formation or loss of the limb. Absolute indications for fasciotomy are: 1) clinical signs of acute compartment syndrome, 2) raised tissue pressure greater than 30 mmHg in a patient with the clinical picture of compartment syndrome, and 3) interrupted, arterial circulation to an extremity for greater than four hours.
Pediatric Fractures—Growth Plate Injuries
The epiphyseal plate (physis) is the growth cartilage of the long bones of children. It is most frequently injured after the age of 10. Physeal injuries have been reported to account for between 15% and 30% of all skeletal injuries in children.29-31 One study suggested that 15% of these injuries result in physeal arrest.32 Another study, however, demonstrated that proper therapy of these injuries reduced the incidence of physeal arrest to 1.4%.30 The generation of the fracture line through the growth plate is used to categorize fractures using the Salter-Harris Classification System described in 1963.32 (See Figure 13.)
• Type I. Complete separation of the epiphysis from the metaphysis without osseous fracture. The growing cells remain on the epiphysis.
• Type II. The most common growth plate injury; these fractures extend out of the physis through the metaphysis.
• Type III. This intra-articular fracture extends from the joint surface to the epiphyseal plate, then along the plate to the perimeter.
• Type IV. Intra-articular fractures extending from the joint surface through the epiphysis, across the entire physis and through a segment of the metaphysis.
• Type V. Type V injuries are crush injuries of the epiphysis.
AP and lateral radiographic views are required to diagnose growth plate injuries; comparison views of the contralateral bone may often assist in determining the difference between an irregular physis and a fracture. Complex fractures may require plain tomography or CT scan, especially those of the distal tibia or those Type III and IV fractures in which the degree of displacement may be the deciding factor for open reduction and fixation.
Type I fractures are most frequently encountered in infants and toddlers. The injury mechanism generally involves a shearing, torsion, or avulsion movement, which essentially produces a separation through the growth plate. Closed reduction of Type I fractures is relatively easy, if diagnosed early. The prognosis for ensuing growth is good unless there has been damage to the arterial supply of the epiphysis, which is seen with injuries involving displacement of the capital femoral epiphysis or the epiphysis of the head of the radius. Type II injuries occur most often in children older than 8 years of age and involve a fracture line that passes through the epiphyseal plate; the epiphysis is laterally displaced, tearing the periosteum on one side while leaving it intact on the side of the metaphyseal fracture. Type II fractures are easily reduced due to the intact periosteum on the fracture side. Because circulation to the epiphysis remains intact, the prognosis for growth is good. Displaced Type I or II fractures that require reduction are treated with complete limb splint for 6-8 weeks.
Type III fractures are uncommon, and occur at the upper or lower tibial physis. Intra-articular shearing forces cause the injury; the fracture line passes through the epiphysis. Accurate reduction of a Type III fracture is essential to restore the joint surface. Prognosis for growth is good provided that the blood supply to the fractured epiphysis remains intact. More than 2 mm of displacement suggests the need for surgery with open reduction. Type IV injuries are most commonly seen at the lower end of the humerus, with the fracture line passing through the metaphyseal and epiphyseal portions of the bone. Unless the fracture is non-displaced, open reduction is always necessary to restore the smooth joint surface. The physis must be perfectly aligned to prevent premature closure of the growth plate. Type V fractures are severe crush injuries through the epiphysis damaging a portion of the physis. These injuries are uncommon but can lead to severe growth reduction problems. Because of minimal displacement, this fracture is often difficult to detect radiographically. As the prognosis for continued bone growth is poor, localized physeal tenderness should increase suspicion for a Type V fracture. Maintaining non-weight-bearing for three weeks can reduce the risk of premature growth arrest.
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