The Fractured Femur PDF

The Fractured Femur The femur is the longest and strongest bone in the body. As such, strong force is required to break the bone. The most common cause of femur fracture in the general population is car accidents. In the pediatric population, fractures of the femur are often a sign of child abuse an...

The Fractured Femur The femur is the longest and strongest bone in the body. As such, strong force is required to break the bone. The most common cause of femur fracture in the general population is car accidents. In the pediatric population, fractures of the femur are often a sign of child abuse and should be documented and reported, as appropriate. And in the elderly (defined as individuals aged older than 65 years), femur fractures most often result from falling and significantly increase mortality and morbidity. Because the femur connects to the hip joint, femur fracture often is associated with hip fracture or injury. In fact, a hip fracture usually is some type of fracture of the femur. The femoral head fits into the hip socket up to the femoral neck. A fracture to the femoral neck or femoral head typically results from high-impact trauma, such as that from a car or bicycle accident. A fracture of the femoral neck can disrupt the blood supply to the femoral head and may result in hip dislocation, avascular necrosis, or other complications. Symptoms In the case of high-impact trauma, it is often obvious that the femur has been fractured, particularly in the case of a femoral shaft fracture that is abrupt and causes sudden, immediate pain. Stress or insufficiency fractures that are not pronounced may be apparent by pain in the upper leg or hip, and it may be extremely painful or even impossible for an individual to place any weight on the affected leg. The fractured leg may be deformed or shorter than the opposite leg, and the femur may even rip through the skin on the thigh in cases of severe fracture. Fractures of the hip, including the femoral head or femoral neck, are often evidenced by pain in the hip, knee, or lower back. Other common, and somewhat more specific, symptoms include the inability to stand or walk and the foot on the affected side turning at an abnormal angle, making the leg look shorter than the leg on the unaffected side of the body. Statistics and risks As many as 250,000 hip-joint fractures occur in the United States each year, and the majority of hip fractures are the result of falling, particularly in the elderly population. In fact, more than one-third of Americans older than 65 years of age fall each year, and 90% of all hip fractures occur in individuals older than age 50. Approximately one-third of American women who live to be older than age 80 experience a fracture of the hip or hip joint, causing complications and increasing morbidity and mortality. More specifically, 15% to 25% of elderly individuals who suffer a hip fracture die within 1 year. Up to 90% of femoral shaft fractures in adolescents and the general population are caused by motor vehicle accidents, including cars, bicycles, or being struck by a vehicle as a pedestrian. Femur fractures also often result from sporting accidents; illness or disease that affects bone integrity, such as vitamin D deficiency, systemic lupus erythematosus, or cancer; and certain medications, particularly long-term use of bisphosphonates for osteoporosis and cancer-related metastases. Femoral neck stress fractures occur most often in highly active individuals, such as elite distance runners, military recruits, and dancers. Another group with a disproportionately high risk of femoral neck stress fractures includes postmenopausal women and individuals with conditions resulting in loss of bone mineral density, including osteopenia, osteoporosis, Paget disease, and hyperparathyroidism. Stress fractures to the femoral neck are uncommon in the general public and exceedingly rare in children. Although most femur and hip-joint fractures in the general population are the result of an accident, certain factors can increase the risk of these fractures in the elderly population, including: • Low bone mineral density. • Bone-related medical conditions, such as osteoporosis or cancer-related bone metastasis. • Conditions that make an individual more prone to falling, such as dementia and visual impairment. • Personal and familial (maternal) history of fracture. • Excessive consumption of alcohol or caffeine. • Physical inactivity. • Low body weight. • Tall stature. • Medications that affect bone mineral density, such as psychotropics and long-term use of bisphosphonates. Similar to the pediatric population, femur fracture in the elderly can be a sign of abuse, and any suspicions of abuse should be reported to the proper authorities. More than 250,000 sub-capital hip fractures below the femoral head are reported annually in the United States, costing an estimated $15 billion per year. By 80 years of age, an estimated 20% of white women and 10% of white men will suffer a hip fracture, most of which are secondary to osteoporosis. The number of individuals older than 65 years is estimated to rise from approximately 35 million in 2000 to nearly 71 million by 2030, and with the aging population it is estimated that the incidence of femur and hip fractures in the elderly will increase from 12.4% in 2000 to 19.6% by 2030. Anatomy-Skeletal The femur is the upper bone of the leg, sometimes referred to as the thighbone. Its function is to allow for walking by connecting the hip to the knee. The femoral head is a ball that fits into the socket joint of the hip at the acetabulum. This ball-and-socket system is held in place by ligaments, or ligamentum teres femoris. The femoral neck connects to the shaft of the femur at an angle to allow for ambulation. The femur is almost completely cylindrical (see Figure 1). Like other long bones, the femur consists of a body and 2 extremities (upper and lower). The upper (proximal) extremity is made up of the femoral head, neck, and greater and lesser trochanters. The lower (distal) extremity is cuboid and consists of 2 oblong projections called the lateral condyle and the medial condyle. The condyles are separated by the recessed patellar surface that connects with the bones of the knee. The femoral head fits into the hip socket and is round. It is directed upward, medialward, and slightly forward. There is a depression on the femoral head, called the fovea capitis femoris, where the head attaches to the ligamentum teres. The weight of the human trunk rests on the 2 femoral heads. The femoral neck connects the femoral head to the femoral body. The neck is a flattened pyramidal process of bone that forms an angle opening medialward. This angle is widest in infancy and becomes narrower as an individual ages. In adults, the femoral neck forms a 125° angle with the body. The structure of the femoral head and neck allows transmission of body weight, as well as the load-bearing and torsion associated with walking. The greater and lesser trochanters are the prominent processes that allow the muscles to move the femur. The greater trochanter is located at the top of the femur at the junction of the femoral neck and the upper femoral body. In adults, it is about 1 cm long. The lesser trochanter also is located at the top of the femur, projecting from the lower and back part of the base of the femoral neck. The femoral body, or shaft, is cylindrical and slightly arched so that it is convex on the front side and concave on the back side. The femoral body has 3 borders separating 3 surfaces: the linea aspera, which is a prominent longitudinal ridge located on the posterior side of the bone; the medial border, which runs from the intertrochanteric line to the anterior extremity of the medial condyle; and the lateral border, which extends from the anteroinferior angle of the greater trochanter to the anterior extremity of the lateral condyle. Bone is metabolically active tissue. During an individual’s lifetime, it continuously undergoes destruction and replacement, known as remodeling. The rate of bone turnover varies by age. Bone production is more rapid than bone breakdown in children, evidenced by their growing skeletons. The rate of bone replacement is slower in the elderly, and their bones gradually become thinner and more fragile, making them more prone to fractures. Vascular Blood is supplied to the majority of the lower extremities through the femoral artery. The femoral artery is a continuation of the external iliac artery in the anterior part of the thigh. The external iliac artery divides into 2 arteries at the hip, the larger and deeper artery known as the deep femoral artery on the medial side of the body and a smaller, more superficial branch of the femoral artery on the lateral side. It is estimated that injury to the femoral artery occurs in 2% of individuals with femur shaft fractures. These injuries can lead to complications or, rarely, death if severe hemorrhaging occurs. Blood is delivered to the femoral head by 3 terminal arterial branches. The predominant branch is the lateral epiphyseal artery, which is an ascending branch of the medial femoral circumflex artery that provides 90% of blood circulation to the femoral head. The 2 additional supporting arteries are the inferior metaphyseal artery, which is the ascending branch of the lateral femoral circumflex artery, and the medial epiphyseal artery of the ligamentum teres. Maintaining the blood supply to the femoral head and neck is important because fractures to this area can have damaging effects on the already tenuous blood supply, and the severity of vascular disruption correlates with the degree of displacement of a fracture. The most common site of avascular necrosis is the femoral head, often caused when a fracture of the femoral neck disrupts the vascular supply. However, osteonecrosis also can result in the absence of a fracture, particularly in alcoholic individuals or individuals taking high-dose steroid therapy because of an increase in bone marrow fat. On radiographs, one of the earliest signs of avascular necrosis — whether due to fracture or other factors — is mixed areas of sclerotic and lytic change. The sclerotic areas represent normal bone that has died and that can no longer undergo remodeling activity. The femoral head may eventually collapse, resulting in deleterious changes in the hip joint. Growth Plates Femur fractures may be particularly problematic in children because their bones are still forming. Like all long bones, the femur consists of a diaphysis, or shaft, with an epiphysis on each end. In children, each epiphysis has a metaphyseal section containing a physis, or growth plate (also referred to as an epiphyseal plate), that has not yet ossified into bone. The growth plates are areas of developing cartilage that regulate and determine the length and shape of mature bone, so a disruption or fracture to the growth plate can result in persistent or severe pain, deformity (i.e., the affected leg remaining shorter as the unaffected leg continues to grow normally), or disability. Types of Fractures Multiple factors lead to the many types of bone fractures. A stress fracture is an overuse injury that results when the muscle becomes too fatigued to absorb shock and transfers the overload of stress to the underlying bone. Stress fractures may not be evident on initial radiographs and often are not visible until a periosteal reaction occurs, drawing attention to the area. On radiographs, a stress fracture often appears as a sclerotic band across the bone, although a defined fracture line is invisible. In such cases, radionuclide bone scanning is possibly the best imaging modality; stress fractures appear as areas of increased uptake before any changes are visible on radiographs. Insufficiency fractures are a type of stress fracture caused by weakened or abnormal bone, often the result of osteoporosis or osteomalacia. These fractures can occur during normal activity or from minimal trauma. Similarly, pathologic fractures occur spontaneously (i.e., without a fall or impact) in abnormal bone, particularly in the presence of bone tumors. Often, a bone lesion is obvious; however, sometimes the borders of the lesion can be poorly defined, and diagnosis requires recognizing the irregularity of the margins of the fracture. Imaging other parts of the skeleton may help to confirm or rule out suspicion of bone metastases. Conversely, fatigue fractures result from abnormal stress being placed on normal bone. Compression fractures occur when bone collapses either because of excessive pressure or illness. These types of fractures occur most commonly in the vertebrae, sacrum, pubic rami, and femoral neck. Salter-Harris fractures are those that occur to the growth plates, almost always due to force. Nonaccidental fractures are linked with abuse, particularly in children but also in the elderly. Radiologic technologists, radiologist assistants, and interpreting physicians should be aware of potential abuse, which is often indicated by multiple fractures, particularly fractures that appear to have taken place at different times. Other factors pointing to nonaccidental injury include epiphyseal and metaphyseal fractures, which often appear on radiographs as small chips from the long bones (corner fractures) that likely result from twisting or pulling the limbs. Periosteal reaction, such as hemorrhage under the periosteum, and rib fractures often are indicative of abuse, and computed tomography (CT) scans or ultrasonography of the head may be necessary to detect brain damage or subdural hemorrhage. A skeletal survey including radiography of the skull, chest, abdomen, pelvis, long bones, and extremities may be useful in documenting abuse, particularly in children. Classifying Fractures Clinicians have created several systems to classify fractures of the femur, femoral head, femoral neck, and growth plates. Fractures can be located on the proximal, middle, or distal third of the femoral shaft, and they can be characterized in several ways, according to: - The direction of the fracture line. - The relationship of the bone fragments involved. - The number of fragments involved. - Any exposure to the outside air. The direction of the fracture line often depends on the type of force causing the trauma. Transverse fractures are horizontal breaks across the femoral shaft and are caused by a force exerted perpendicular to the shaft. Force applied in the same direction as the long axis of the bone produces diagonal or oblique fractures across the shaft. Longitudinal fractures also occur along the long axis of the bone. Finally, spiral fractures encircle the femoral shaft and are produced by a torque injury. Fractures also can be described according to the relationship of the bone fragments to one another. The fracture can display 1 or a combination of the variations in position: - Displacement: misalignment of the fragments; represents the distance the distal fracture fragment is offset from the proximal fracture fragment. - Angulation: the amount of deviation from the normal angle of the distal and proximal fragments. - Shortening–the amount of overlap in the ends of the fracture fragments. - Rotation–the extent the fracture fragments pivot or turn from normal position. The shape of the fractured ends can be straight across (transverse) or angled (oblique). Simple fractures consist of 2 bone fragments; fractures that involve multiple fragments are known as comminuted. Open, or compound, fractures expose the bone to the outside air and often involve more injury to the surrounding muscles, tendons, and ligaments. The skin remains intact in closed fractures. Salter-Harris fractures involve the femoral growth plates, either alone or combined with an adjacent part of the femur. This classification system includes 5 types and is particularly important because of its predictive value. Type I and type II fractures are associated with a good prognosis, whereas type IV and type V can result in early fusion of the epiphysis and subsequent shortening of the bone. Fractures of the hip are classified according to 4 subtypes: intertrochanteric fractures, subtrochanteric fractures, femoral head fractures, and femoral neck fractures. An intertrochanteric fracture is the most common type of hip fracture and involves a fracture line between the greater and lesser trochanters. Intertrochanteric fractures also carry the best prognosis of any hip fracture, particularly in healthy individuals. Subtrochanteric fractures occur at the femoral shaft below the lesser trochanter. Femoral neck fractures are referred to as intracapsular or subcapital, meaning within the softtissue capsule that contains the lubricating and nourishing fluid of the hip joint in the region between the femoral neck and the femoral head or greater trochanter. Because the femoral neck is narrow and weak, it is prone to fracture. Because it absorbs much of the compression and force associated with walking, the daily load on the femoral neck produces stress on the bony structure. In runners and elite athletes, the amount of force to the femoral neck is multiplied exponentially. An untreated stress fracture to the femoral neck can result in pain, hip displacement, and disability. A fracture to the femoral neck disrupts the blood supply to the femoral head and can result in hip displacement as well as necrosis of the femoral head. Femoral neck fractures are categorized according to the Garden Classification, which includes: - Type 1–stable; involves a minor crack in the femoral neck. - Type 2–involves a complete crack in the femoral neck but no bone displacement. - Type 3–a displaced fracture with the fragments remaining connected to one another; also may involve rotation of the bone fragments, angulation, or both. - Type 4–completely displaced with no connection between the fractured fragments; likely to disrupt blood supply to the femoral head. The Pipkin Classification, proposed in 1957, is the most widely used classification criteria for femoral head fractures. According to this system, fractures are categorized into 4 types based on increasing severity. The classifications influence treatment decisions and predict outcomes. For example, type I fractures typically have better outcomes and often are managed without surgery, using physical therapy and limited weight bearing. In addition, the occurrence and severity of complications increase from type I to type IV. Diagnostic Imaging Radiography With bone fracture, radiographs remain the gold standard for diagnostic imaging. In the United States, nearly every patient who presents to the emergency department with a suspected fracture undergoes plain-filmradiography. Not only can radiographs be used to visualize fracture or dislocation, they also can help determine whether underlying bone is normal or whether a fracture occurred because of an abnormality (ie, a pathological fracture). Radiography can be used to distinguish a fracture from other conditions or diseases, such as cancer and bone metastases, osteomyelitis, Paget disease, or dislocation. Radiography also can show the position of the bone ends before and after treatment of a fracture, and it can be used to assess healing and complications. In the case of bone trauma, at least 2 projections are required: anteroposterior (AP) and lateral, ideally at right angles to one another. This is because sometimes a fracture or dislocation will be seen on only 1 radiograph and would be missed without the second image, especially when fracture fragments are minimally displaced. To this end, the position of a fracture must be assessed with more than 1 image. For the AP projection, the patient should be positioned supine with the femur centered over the image receptor. The central ray should be midshaft. In cases of suspected or known femur fractures, the radiologic technologist would use a cross-table lateral projection. If the images do not include both joints, an additional radiograph should be taken of the other joint. In areas of more complex bony anatomy, such as the joints, more than 2 projections may be needed to assess any trauma adequately. In this case, additional oblique or other projections may be useful for diagnosis. Radiographic imaging of the entire bone is helpful because fractures can occur at more than 1 site and additional pathology may be present. Additional images also must be taken if both joints (knee and hip) do not fit on initial imaging. Often with severe trauma to the femur, fractures are obvious and visible without radiologic imaging (eg, a large dome-like lump on the thigh). On radiography, a fracture usually appears as a lucent line, which may be thin and easily overlooked. Other times, a fracture may appear as a dense line that occurs when bone fragments overlap. Even with 2 projections, fractures may be invisible on radiographs, in which case additional projections should be performed at the discretion of the radiologist as follows: • Oblique projections. • Stress images, which are taken with a joint under stress to show that it is unstable, as in the case of dislocation. • Flexion and extension projections, which should only be taken with the individual performing the movement and not on an unconscious individual. • Radiographs of the nonfractured side for comparison. Intracapsular fractures (ie, those above the trochanters) usually are apparent on radiographs; however, when a fracture is not evident and clinical suspicion of a fracture is high, magnetic resonance (MR) imaging may be preferred. Often, acute injuries to the growth plates are not clearly visible on radiography because of the cartilaginous-osseous composition and irregular contours of the physes. The epiphyseal growth plate appears on radiographs as a white boundary, making it easily confused with an impacted fracture in which trabeculae have become enmeshed. The 2 can be distinguished because the growth plate margin is almost completely smooth and curved, whereas a fracture line is an abrupt interruption of the cortex. Because radiographs may show physeal widening as the only sign of displacement, 2 projections (AP and lateral) are needed. Imaging of the unaffected leg may help with diagnosis via comparison, particularly with type I Salter-Harris fractures. In the case of type V Salter-Harris fractures, changes to the bone often are missed on plain radiographs. Although varus and valgus stress projections may be indicated in certain individuals to demonstrate separation between the epiphysis and the metaphysis, particularly in injuries around the knee, stress maneuvers may cause further damage in other individuals and should be performed with caution. Femoral neck fractures often occur in elderly individuals because of falls. In the elderly population in particular, it is important to distinguish between fractures of the pelvis and nondisplaced, impacted, or occult fractures of the femoral neck. Radiographic imaging of the femoral neck should include AP images and images of the lateral ipsilateral femur with internal rotation. Because a patient should not be turned on their side if they have a fractured femoral neck, a cross-table lateral projection is needed. A fracture of the femoral neck appears on radiography as dark streaks across the bone where the continuity of cortical and spongy bone is interrupted. Initial radiographs of femoral neck fractures are often negative, particularly if the fracture is nondisplaced. It may take a few days, after the bone has become slightly displaced or bony resorption occurs adjacent to the fracture line, for the fracture to become apparent on radiography. MR imaging may be most useful for immediate diagnosis, while bone scans are helpful after a minimum of 3 days. Typically, fatigue fractures are seen in the medial femoral neck in young individuals, whereas insufficiency fractures may also involve the acetabulum or pubic rami in elderly individuals (see Figure 4). Radiographic imaging of the hip also should include an AP and a lateral projection. The AP image should be captured with the patient supine and the foot internally rotated 15° to secure the best view of the femoral neck. The central beam should be directed toward the femoral head. The x-ray tube should be positioned 100 cm from the focal plane of the image receptor to produce an image at 20% magnification. The cross-table lateral projection should be taken when an individual is suspected of having a hip fracture or dislocation, whereas a “frog leg” lateral view should not be performed on an individual with a suspected hip fracture or dislocation. For the cross-table lateral projection, the patient should be supine, with the opposite hip flexed and abducted. The cassette should be placed against the lateral side of the affected hip, and the central beam directed horizontally toward the groin, with approximately a 20° angle of cephalic tilt. Because occult hip fractures often are missed on radiography in the emergency setting, Chiang et al investigated the diagnostic signs and measurements for occult femoral neck fractures in the elderly using radiographs taken in the emergency department. In the study, all radiographs were evaluated by an orthopedist and a radiologist, and initial negative radiographs of individuals later found to have femoral neck fractures were compared with radiographs of individuals without hip fractures. Diagnostic signs included AP, lateral, and medial evidence, and measurements included elevation of the fat pad and external rotation of the femur. After evaluation, the results showed that individuals with femoral neck fractures had at least 1 radiographic sign on initial radiography. Using the positive lateral or posterior sign as diagnostic criteria, sensitivity was 0.875 and specificity was 0.906. When the fat pad elevation was greater than or equal to 1.5 mm, sensitivity was 0.867 and specificity was 0.857. From this analysis, the authors concluded that although MR imaging has been and will likely remain the gold standard for diagnosing occult femoral neck fractures, radiography in the emergency setting can be of benefit, particularly with the lateral and posterior signs and elevation of the fat pad greater than or equal to 1.5 mm as diagnostic references. A retrospective study by Collin et al investigated observer variation for radiography, CT, and MR imaging of non-displaced occult hip fractures to gauge the effect of observer experience and patient age on interpretation of results. Images from 375 individuals were collected, and all consisted of radiography followed by CT or MR imaging. Three radiologists with varying degrees of experience interpreted the images, and observer variation was assessed using linear weighted kappa statistics. Results indicated that observers agreed on diagnostic findings for almost every CT and MR image. Unexpectedly, observers did not always agree on diagnostic findings on the radiographs, even though radiography is the gold standard for diagnosing fracture. For radiography, agreement was moderate to substantial for intracapsular fractures. Furthermore, observer experience affected agreement only with radiography. Magnetic Resonance Imaging MR imaging plays an important role in the diagnosis of femur fractures. In particular, MR can be used to assess soft-tissue damage resulting from femur fracture, and it is superior to CT in its ability to visualize soft tissue. MR imaging also is used to assess tissue composition and image lesions in multiple planes and to accurately delineate geographic relationships of the body’s internal structures. In the emergency setting, MR remains the imaging modality of choice for occult hip and pelvic fractures, particularly in the elderly. Hip fractures, especially those that are not displaced, often are missed on radiography. MR imaging is indicated in nonambulatory patients with negative radiographic images, and both insufficiency fractures and stress fractures appear as characteristic bone marrow edema on MR imaging. Detecting hip fractures early ensures patients are properly treated and minimizes complications, (eg, deep vein thrombosis, loss of strength, and decreased cardiac output) that result from prolonged immobilization and hip surgery. A retrospective review of Duke University’s MR imaging database from July 2005 through June 2008 found that the average age among individuals imaged for lower-extremity injuries in the emergency setting (N = 92) was 70.8 years, with a range of 19 to 94 years. All of these patients had undergone at least 1 radiographic examination of the hip, pelvis, or femur, with 71 patients (77%) undergoing at least 2 x-ray examinations, for a total of 97 images. Approximately 70% of the patients had documented trauma; the most common reason for imaging in elderly patients was a fall, whereas the most common reason for imaging in patients younger than 50 years of age was a motor vehicle collision. Two musculoskeletal radiologists interpreted the MR images for fractures, muscle injury, and other conditions. From the review, it was found that MR detected 23 fractures of the hip or pelvis in 13 patients with normal radiographic findings on initial interpretation. In addition, MR revealed 12 pelvic fractures not identified on initial radiographs. Without MR imaging, it is likely that 11 patients would have undergone unnecessary corrective procedures (ie, bone pinning) because of false-positive radiographic findings. Another retrospective study conducted in London found similar results — particularly that MR was able to detect proximal femur fractures originally missed on radiography. In this study, 102 individuals who were admitted to the hospital with reports of hip pain, mostly after a fall, were examined first with radiography and then with MR imaging if the treating clinician suspected a fracture, even if initial radiographs were negative. In total, MR imaging revealed abnormalities In 81 individuals (83%), of which 42 individuals (43%) had proximal femur fractures. Clinicians were able to stabilize and treat the majority of the fractures detected without surgery, particularly incomplete intertrochanteric fractures, as long as individuals were able to bear weight at least partially on the affected leg. Thus, this study adds to the credibility of MR imaging in individuals with difficult-to-diagnose femur fractures that would have been missed on radiographs alone. In a case report and literature review by Cheon et al, the utility of MR imaging in diagnosing insufficiency fractures of the femur not immediately evident on radiography was evaluated. Researchers examined 7 women who were on long-term bisphosphonate therapy, which has been linked to low-energy subtrochanteric and diaphyseal femoral fractures. All individuals had suspected impending fractures. Their mean age was 66.1 years, with a mean duration of time on bisphosphonate therapy of 49.9 months. MR imaging was performed with a 3.0-T system and included 3 pulse sequences: - Coronal, sagittal, and axial T2-weighted fast spin-echo (4100/100 [repetition time ms/echo time ms]). - Coronal, sagittal, and axial T1-weighted imaging (760/12). - Coronal, sagittal, and axial fat-saturation enhancement (850/12). Radiographic images were compared with MR images, and the results indicated that 4 of the 7 individuals studied had impending fractures, as indicated on MR imaging (see Table 1). The presence of the femoral cortical ridge on radiography appeared as a complete transverse fracture line on MR imaging, leading the authors to postulate that this finding indicated the potential for fracture and possible need for prophylactic fixation. Moreover, the authors stated that although MR imaging is the most effective modality for diagnosing stress fractures of the tibia and femur in athletes, it is also effective in evidencing impending fractures in women at risk for such injury as a result of long-term bisphosphonate use. MR imaging is not as effective as radiography or CT in showing fracture lines because cortical bone does not produce an MR signal. However, MR imaging is useful in showing bony injuries often not obvious on CT scans, such as bone bruises that do not involve cortical bone disruption but do result in hemorrhage and edema in the bone marrow. This is because bone bruises, for example, cause hemorrhage within the bone that replaces the marrow with fat, thereby altering the MR signal. An altered signal may be visible in the presence of a hemorrhage, and a bone bruise may be visible even without a discernible fracture on a radiograph. MR imaging can depict altered arrest lines and transphyseal bridging abnormalities before they are evident on radiographs. In addition, coronal MR imaging can be used to image a fracture to the femoral neck not visible on radiographs of the hip. With fractures of the growth plate, MR imaging is the most accurate modality in showing fracture anatomy in the acute phase of injury (ie, the first 10 days following injury). On T1-weighted MR imaging, fractures appear as a transverse band of low-intensity (bright signal) marrow replacement. On T2-weighted imaging, fractures appear as high signal surrounding edema. Computed Tomography Compared with radiography, CT has the distinct advantage of more clearly showing obvious fracture lines as well as cortical abnormalities associated with nondisplaced fractures. CT can show fracture lines in greater detail, as well as the position and orientation of fracture fragments, better than other imaging modalities. CT particularly is useful for imaging fractures in complex skeletal structures, such as the hip, face, shoulder, and foot. CT can produce sagittal and coronal reformations, as well as 3-D models of the injured area, that display the position and orientation of major fracture fragments and allow for viewing of the bone as if the soft tissues were removed. Although CT has been shown to be less sensitive than MR imaging in detecting fractures, CT is recommended for individuals who cannot tolerate MR imaging. With fractures around the hip joint, CT can show the relationship of the fragments to the joint as well as any loose fragments within the joint. CT also demonstrates tissue damage and hematomas that can result from fractures. CT is often quicker and more comfortable, requiring less body manipulation than radiography, making it advantageous for seriously injured individuals, such as those involved in a car accident. Melvin et al conducted a small study to assess the utility of CT for detecting and managing femoral neck fractures, which are common in the elderly. Their hypothesis was that adding CT scanning to the imaging regimen would increase agreement among clinicians about classifying femoral neck fractures according to the Garden Classification and about the best method of treatment. Participants were aged 65 years or older and underwent imaging with radiography alone, CT alone, or radiography and CT combined. Researchers found that the addition of CT, as well as modification of the Garden Classification as nondisplaced vs displaced, improved intraobserver reliability in interpreting the findings in the 5 cases included in the study. Classification of femoral neck fractures was more likely to change when CT was combined with radiography, and agreement regarding classification was improved with the addition of CT. However, treatment was not affected by adding CT to the imaging regimen in this study. Instead, it appeared that the medical specialty of the attending physician was more influential over treatment decisions. For example, surgeons trained in arthroplasty (hip reconstruction) were more likely to recommend total hip arthroplasty than hemiarthroplasty compared with surgeons not trained in arthroplasty. Although the role of CT in detecting femoral neck fractures is limited and does not appear to have much effect on treatment, at least not in this small study, CT can be useful as an adjunct imaging modality, particularly in the elderly. Nuclear Medicine Scintigraphy Radionuclide bone scanning (also referred to as bone scintigraphy) with technetium 99m-labeled diphosphonate tracer material plays a role in diagnosing fractures because of its high sensitivity compared with other imaging modalities. The diphosphonates accumulate rapidly in the bone, and almost 50% of the tracer is absorbed by the skeletal system within 2 to 6 hours after injection. The rate of uptake of the radiotracer depends on blood flow and new bone formation. Thus, radionuclide bone scanning can be used to show signs of bone healing, as well as cell turnover and other physiological signs of fracture. Scintigraphy particularly is useful in diagnosing fractures that are not immediately visible on radiography, namely hip fractures and stress fractures in the legs. With nondisplaced fractures, such as those common to the femoral neck, a bone scan can reveal increased isotope uptake at the site of the fracture. Most fractures are detectable on radionuclide bone scans within 24 hours. However, in elderly individuals with osteopenia, fractures may not be visible within 24 hours of injury and may require additional bone scans at 72 hours for detection. Bone scans particularly may be useful in showing stress fractures, plantar fasciitis, and shin splints in athletes, all of which may not be visible on radiographs. Radionuclide bone scanning also is used to diagnose bone tumors or cancer, rule out a bone infection or avascular necrosis, and evaluate metabolic disorders that affect the bones (eg, osteoporosis or Paget disease), thereby distinguishing such conditions from a fracture. For example, on bone scans, osteomyelitis almost always appears as a combination of focal hyperfusion, focal hyperemia, and focally increased bone uptake. Because this modality can be used to show cell turnover, it is useful for examining skeletal lesions. Bone metastases typically appear on bone scans as multiple foci of increased activity, although they occasionally appear as areas of increased uptake of tracer material. FDG-PET Like scintigraphy, positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) scanning can be used to examine an individual for abnormal processes in the bone; however, its use in detecting femur fractures is limited. FDG-PET measures metabolic activity and molecular function via injected radiopharmaceutical that is absorbed into the body, emitting radiation that is detected by the PET scanner. Because cancerous cells grow more rapidly than noncancerous cells, the high absorption of the glucose-based radiopharmaceutical by malignant cells allows for cancer diagnosis. In fact, the reported sensitivity of FDG-PET in detecting bone metastases is approximately 90%. In the case of femoral fracture, FDG-PET may be helpful in distinguishing fracture from bone metastases. However, FDG-PET has been shown to have a high false-positive rate, is more expensive than standard radionuclide bone scanning, and is less readily available than MR imaging. SPECT Single photon emission computed tomography (SPECT) is another type of nuclear medicine examination that uses radiotracer material to generate gamma decay to obtain images. Like CT, its images can be formatted in multiple planes. With femur fracture examination, SPECT may assist in evaluating femoral neck stress fractures in conjunction with planar scintigraphy. In a retrospective study of 38 individuals in the military, 33 had undergone planar scintigraphy with SPECT before MR imaging of the hip for the evaluation of femoral neck fracture. When SPECT was added to planar scintigraphy, sensitivity rose from 50% to 92.3%, and accuracy in detecting high-grade fractures improved from 12.5% to 70%. When SPECT is an option, the authors suggested that it be added to bone scintigraphy for evaluating individuals with suspected femoral neck fractures. Dual-energy X-ray Absorptiometry Dual-energy x-ray absorptiometry (DXA) may have a potential role in detecting femur fractures, although it most commonly is used to detect changes in bone density. Bazzocchi et al retrospectively reviewed 739 DXA examinations to detect collateral findings and understand their effect on patient care. The review included 231 examinations of the lumbar spine, 221 of the femur, 191 of the whole body, and 96 of the vertebrae. Incidental findings were noted in 117 (15.8%) of the DXA examinations, 27 of which involved the femur. Of these incidental findings, 50 (42.7%) were confirmed using another imaging technique. However, none of the incidental findings were mentioned in the DXA reports. Based on these results, the authors stressed that when DXA is used to evaluate bone integrity or possible fracture, interpreting clinicians should evaluate DXA images for their potential in qualifying collateral findings related to diagnosis. Other Imaging Modalities PET scan coupled with CT (PET-CT) has shown promise as a potential imaging modality for individuals with osteoporosis and atypical femoral shaft fractures because of its usefulness in defining certain aspects of pathogenesis, site specificity, and potential prodromal abnormalities, in addition to providing insight about radiokinetic variables of skeletal blood flow and markers for bone formation. However, more studies on the clinical use of PET-CT as a diagnostic imaging modality for femur fracture are warranted. Ultrasonography plays a limited role in bone assessment, mostly in the imaging of joint effusions, blood flow, and the presence of foreign bodies within the soft tissues. Ultrasoundguided femoral nerve blocks may be used in the emergency setting to achieve adequate analgesia for severe femoral fractures. Finally, high-resolution peripheral quantitative CT (HR-pQCT) has shown promise in recent years because of its ability to image bone density and isotropic voxel size, which may prove helpful in assessing osteoporosis and fracture risk as well as treatment efficacy. Treatment and Management Treatment of femoral fractures ranges from immediate stabilization of a patient to surgery. In the emergency setting, the first step is to stabilize the patient and address any fluid or electrolyte abnormalities. Weight should not be placed on the affected leg or hip until a workup is conducted. Because the femoral area is vascular and trauma can be associated with blood loss, up to 40% of isolated femoral fractures require blood transfusion, which is particularly troublesome in the elderly population because they have less cardiac reserve. The goal of treatment for femoral fractures is to avoid complications and restore anatomic stability and mobility as quickly as possible. Femoral Shaft Fractures In the adult population, fractures of the femoral shaft are most often treated surgically with intramedullary nails or plate fixation. Other treatments include external fixation, although this procedure is less common and generally only a temporary solution. Although nonsurgical treatments for femur fracture exist, including skin traction, skeletal traction, cast brace, and casting, these methods are rarely used except for pediatric patients. Intramedullary nail fixation involves the insertion of a metal rod, typically titanium, into the marrow canal of the femur. The nail reattaches the fractured bone fragments to one another so that they can be realigned and heal. With this procedure, the nail is inserted either at the hip or the knee and is anchored to bone on both ends to keep the nail and the bone in place during the healing process. With intramedullary nail fixation, malrotation at the time of fixation can result in misalignment of the femur, which is the most common type of deformity linked to the procedure. Other complications with this procedure, particularly during distal locking, have spurred research in computer-assisted surgery. Currently, closed reduction and intramedullary nail fixation of femoral shaft fractures are performed under fluoroscopy. However, multiple images are needed during the procedure, partially for distal locking of the nail, which results in cumulative radiation exposure for the surgeon. Computer-aided technologies, such as virtual fluoroscopy and CTbased systems, have proven useful in lowering the dose while allowing for real-time images of the procedure. Intraoperatively as well as postoperatively, clinical examination, fluoroscopy, and ultrasonography can be used to measure femoral rotational alignment, and CT can be useful in determining the degree of malrotation and in surgical planning. In the past, treatment for femoral shaft fractures included traction or splinting; however, these procedures carry a high risk of complications and disability. Traction, in particular, has the disadvantages of poor control of the length and alignment of the fractured bone, risk of developing pulmonary insufficiency or deep vein thrombosis, and joint stiffness due to supine positioning of the patient for long periods of time. With fractures of the femoral shaft, treatment is aimed at preventing delayed union, malunion, or nonunion of the bone — all of which may be increased with compound fractures, delayed weight bearing, and tobacco use. Growth Plate Fractures Growth plate fractures often are treated nonsurgically. Factors that influence treatment include: • • • • the severity, location, and classification of the fracture, plane of deformity, patient age, growth potential of the affected plate. The majority of type I and type II Salter-Harris fractures can be treated with closed reduction and casting or splinting. To avoid additional damage, reduction often centers on traction and less forceful manipulation of the bone fragments. More severe intra-articular fractures (eg, type III and type IV Salter-Harris) usually require open reduction and internal fixation that avoids crossing the physis. Smooth pins are implanted parallel to the physis in the epiphysis or metaphysis. Oblique insertion of pins across the physis is considered only when satisfactory internal fixation cannot be attained with transverse fixation. Type V Salter-Harris fractures often are not diagnosed in the acute phase; thus, treatment is delayed until a more obvious bony formation grows across the physis. Femoral Neck Fractures Femoral neck fractures are notoriously difficult to treat. Management can include nonsurgical methods when the fracture is nondisplaced. However, surgery, including internal fixation, is most often necessary to avoid complications such as delayed union or nonunion, refracture, osteonecrosis, and avascular necrosis of the femoral head. In some cases, arthroplasty and even total hip replacement may be necessary to properly treat a femoral fracture. Internal fixation is still arguably the most common treatment for femoral neck fractures, although its use is tapering off. It involves inserting metal screws that attach to both the femur and the femoral head to secure the femoral neck. The procedure was introduced by Smith-Peterson in 1931 and was widely used until the 1970s. Various other techniques were introduced, and a debate arose over the advantages and disadvantages of internal fixation of the femoral neck vs replacing the entire femoral head. Norway has 1 of the highest incidences of hip fracture. Norwegian researchers conducted a retrospective study of 337 patients to examine factors that contribute to unsuccessful internal fixation of femoral neck fractures. The investigators examined patient radiographs to determine Garden Classification and the cause of the procedure’s failure. Fixation failure, nonunion, and femoral head necrosis were identified as failure points. Twelve patients with nondisplaced fractures (Garden Classification I-II) experienced failed internal fixation vs 59 patients with displaced fractures (Garden Classification III-IV). In the study, a 6-point scale was used to assess the quality of the fracture reduction and placement of hip pins, with 6 representing treatment success. Of the 117 patients with nondisplaced femoral neck fractures, 17 were assigned scores of less than 6 points, and internal fixation failed in only 1 patient. Thus, patients with nondisplaced femoral neck fractures and a lower fixation score had no increased risk of internal fixation failure. However, the same was not true for patients with displaced fractures. For the 220 patients with displaced fractures, there was an increased risk of internal fixation failure for fractures assigned a lower score. In fact, internal fixation failed in 23 (18.3%) of 126 patients with displaced fractures given a score of 6 points and half of patients assigned a score of 3 or less (P = .017). The study authors concluded that closed reduction and internal fixation carry a high risk of treatment failure, and poor reduction of fractures increases the risk of failure particularly for displaced femoral neck fractures. Furthermore, surgery more than 48 hours after the time of injury increases the risk of internal fixation failure of displaced femoral neck fractures. Arthroplasty is another common treatment for femoral neck fractures, especially those that are displaced. This procedure can involve replacing the head or neck of the femur, or both, with a prosthesis (hemiarthroplasty) or total hip replacement. Hemiarthroplasty can be unipolar, meaning that the femoral head is fixed to the stem, or bipolar, meaning that an additional polyethylene bearing is placed between the stem and the endoprosthetic head. The advantages of hemiarthroplasty are that it eliminates the risks of nonunion and internal fixation failure, thereby decreasing the risk of repeated surgery. The debate about which particular type of arthroplasty should be recommended for a particular patient population is ongoing. For example, total hip replacement is infrequently recommended because of its high cost and related complications. However, in patients with arthritis of the hip who sustain a femoral neck fracture, benefits are thought to outweigh risks. Furthermore, studies have suggested that total hip replacement may have an underused role in patients with displaced femoral neck fractures in view of the high failure rate of internal fixation and hemiarthroplasty, as well as improved design features and surgical techniques. Femoral Head Fractures Femoral head fractures often are difficult both to diagnose and to treat. Fractures classified as type I according to the Pipkin Classification often are managed nonsurgically by limiting weight bearing on the affected side, followed by physical therapy. Previously, type II fractures also were treated nonsurgically; however, outcomes tended to be unfavorable. The treatment standard now includes surgical management, although there remains discussion regarding whether free fragments should be fixated or excised. Type III femoral head fractures carry an increased risk of avascular necrosis and require immediate surgical reduction of the associated femoral neck fracture. Management of the femoral head fracture depends on the presence of type I or type II involvement. Severe type III femoral head fractures may require total hip replacement. Finally, type IV fractures involve extensive injury to the acetabulum, which likely requires surgical reduction. In this scenario, the femoral head is treated at the same time as the acetabulum reduction and the surgical direction will depend on type I or type II involvement. The long-term prognosis for Pipkin type IV fractures is poor. Reconstruction of the femoral head with an osteochondral allograft has been investigated as a treatment for severe femoral head fracture. As with femoral neck fractures, hemiarthroplasty or total hip replacement may be warranted to replace all or part of the affected hip in the case of dramatic femoral head fracture. Recovery Physical therapy is almost always initiated following treatment of a femur fracture. Its purpose is to restore hip and knee range of motion and strength. Depending on the fracture pattern, an individual may need gait training for crutch-assisted, touch-down weight bearing. With simple fracture patterns that are stable after surgery, greater weight bearing can be initiated. For femoral stress fractures, use of crutches can be discontinued once an individual can walk without pain. Low-impact lower-extremity aerobic training (eg, swimming, biking, or using an elliptical trainer) can be initiated while symptoms permit. Overall, the goal of postsurgical physical therapy is to achieve range of motion and weight bearing as soon as possible on the affected leg or hip. Conclusion A fracture of the femur is a significant medical event. The femur is the largest and strongest bone in the human body, so great force is necessary to cause it to fracture. However, a fracture of the femur also can result from certain medical conditions, such as osteoporosis or cancer, or from long-term use of certain medications that alter bone turnover and integrity. In adults, the most common cause of femur fracture is motor vehicle accidents. In the pediatric population, femur fractures often result from child abuse and should be documented and reported accordingly. In the elderly, femur fractures most often result from falling. Characterizing femur fractures depends on their location (eg, on the shaft, at the site of a growth plate, or at the femoral neck or femoral head). Classification of femoral shaft fractures is based on 3 types: spiral or transverse, comminuted and involving multiple bone fragments, or compound and open to the environment. Fractures at the growth plates are classified according to Salter-Harris criteria, and fractures of the hip and femoral neck and head have their own respective classification criteria. These criteria are important because they affect treatment decisions and often help determine prognosis. Fractures of the femur often are associated with fractures of the hip. This is because the femoral neck and head meet the acetabulum to form the ball-and-socket joint of the hip, which allows for ambulation. A disruption to this socket can lead to immobilization, disability, and increased morbidity and mortality. In addition, the femoral area is highly vascular, and an injury to the femoral artery can lead to complications and even death if severe hemorrhaging occurs. Diagnosing femur and hip fractures relies on effective radiologic imaging, and radiography remains the gold standard for diagnostic imaging. MR imaging is often useful for diagnosis, particularly in the emergency setting when fractures are subtle or occult. CT may be useful in showing fracture lines in greater detail than plain-film radiography, and CT’s ability to create 3D models can be used to better view the bones and bone fragments. Other imaging modalities play a role in the diagnosis and management of femur fractures, but to a lesser degree than radiography, MR, and CT. With any imaging modality, it is important that the patient be stabilized, particularly in the emergency setting, and that the potentially fractured bones do not move during positioning, causing further damage. Effective treatment of femur fractures is necessary to restore homeostatic function and to prevent complications such as permanent disability, immobility, and even death. Gone are the days when a femur fracture almost certainly meant permanent disability, often in the form of 1 leg being shorter than the other. Today, with medical interventions that include internal fixation, arthroplasty, and even hip replacement, individuals with femur fractures can have positive prognoses with little or no long-term disability.