Femoral Shaft Fractures

Etiology

Femoral shaft fractures can result from high or low-energy mechanisms and are often associated with other serious injuries. The most common causes include automobile accidents, falls from heights, ground-level falls in individuals with osteoporosis, and gunshots. A study from Finland found that 75% of FSFs were caused by high-energy mechanisms, 87% of which occurred in moving vehicle collisions (MVCs) (65% of all fractures). Other less common causes of FSFs are atypical fractures from bisphosphonate use, pathologic fractures through a bone lesion, insufficiency fractures from osteoporosis, and stress fractures from overuse in athletes and military recruits.[11][12][13]

Epidemiology

The worldwide incidence of femoral shaft fractures ranges between 10 and 21 per 100,000 per year. Two percent of these fractures are open fractures.[13][14] The rate of atypical femur fractures, as defined by the American Society for Bone and Mineral Research Task Force 2013, ranges between 3.5% to 16%.[12] FSFs demonstrate a bimodal distribution. Men are more likely to sustain a fracture between the ages of 15 to 35, while women begin to show a steady increase starting at age 60. Men are more likely to sustain FSFs from automobile accidents or other high-energy mechanisms. Women are more likely to sustain an FSF from ground-level falls. Automobile accidents are more prevalent in the younger population, while ground-level falls are more common in the elderly population, which is attributed to osteoporosis.[13][11] Interestingly, the age of presentation with a femoral shaft fracture has increased with time. According to the Edinburgh Orthopedic Trauma Unit in the United Kingdom, the average age of presentation in 1990 was 44, with a steady increase to 65 years in 2000, likely due to more rigorous traffic laws and improved automobile safety.[15]

Pathophysiology

Trauma is the most common mechanism of femoral shaft fractures, typically involving a direct hit to the thigh or an indirect force transmitted through the knee. Younger individuals generally are engaged in high-energy mechanisms such as automobile accidents, frequently resulting in other associated injuries. Gunshots can also cause significant isolated injuries. Individuals with osteoporosis are at an increased risk of fracture, even with low-energy trauma. Irrespective of the mechanism, the deforming forces of a fracture depend on the fracture characteristics. The proximal segment is most commonly pulled into flexion and external rotation by the psoas and abduction by the abductors. The distal fragment is drawn into varus by the adductors, into extension by the two heads of the gastrocnemius, and shortened by the extensor mechanism and hamstrings.  

Associated orthopedic injuries of the femur that must be ruled out include fractures of the proximal femur (femoral head and neck, intertrochanteric fractures) and bilateral femoral fractures. A study demonstrated that simultaneous injuries to the proximal femur occur in 1% to 9% of patients, and 20% to 50% were not identified during the initial evaluation. The presence of associated injuries is clinically relevant because it will determine the order of fixation and implant selection.[16] Bilateral femur fractures account for 2% to 7% of all femur fractures and are associated with increased risk of systemic complications, resuscitation requirements, and mortality. 80% of individuals with bilateral femoral shaft fractures have other associated injuries; therefore, the treating physician should be suspicious of additional injuries. Fat emboli syndrome is a systemic disorder prevalent in a polytraumatized individual with shaft fractures. It classically presents as respiratory compromise, altered mental status, fever, and rash. Manifestations can span the spectrum from subclinical symptoms to acute respiratory distress syndrome. Up to 36% of patients with long bone fractures will require some form of ventilatory support.[17]

History and Physical

The life support protocols must be initiated for every traumatized patient, even those sustaining a ground-level fall, to rule out associated morbidities that may preclude early definitive care. Clinically, shaft fractures manifest as pain, bruising, swelling, deformity, shortening, and instability around the thigh. In the polytraumatized individual, injuries are frequently masked by more severe or painful injuries; therefore, a complete examination is imperative.

Open fractures of the femoral shaft are exceptionally severe injuries and occur in about 2% of all femoral shaft fractures.[18] A thorough exam is essential to rule out open fractures, and if present, prompt administration of antibiotics and tetanus is imperative to reduce the risk of infection. Any gross debris should be removed in the acute setting, and the wound and bone should be covered in a sterile, saline-soaked dressing. Formal irrigation and debridement should follow in the operating room. Open fractures are classified according to the Gustillo-Anderson (GA) or the Oestern and Tscherne classification. Communication with the outside world can lead to significant uncontained bleeding and an increased risk of infection.[19] A study demonstrated an infection rate of 2.3% for GA type I and II vs 17.6% for GA type III.[20] Open fractures do not preclude compartment syndrome that can develop due to blunt trauma and the violent motion of the femur moving through the surrounding tissues. A retrospective study of thigh compartment syndrome identified FSF in 48% of patients; of these, 5 were open.[21] 

Documentation of neurovascular status is imperative. Although rare, a vascular injury may occur with femoral shaft fractures up to 2% of the time, particularly with gunshots and penetrating trauma.[17] Damage to the deep femoral artery (DFA) and its branches is the most common and typically results in significant hemorrhage rather than ischemia due to abundant collateral flow. Because the thigh can hold around 1.5 L of blood, vascular injuries can significantly contribute to a polytraumatized patient's shock state.[19] On the other hand, injury to the SFA causes ischemia to the leg and foot as its first branches arise in the popliteal fossa. The superficial femoral artery (SFA) is a conduit throughout the thigh. If vascular compromise is suspected, characterized by pulselessness, enlarging pulsatile hematoma, bruit, thrill, hemorrhage, and acute ischemia, the extremity should be placed in traction, andankle-brachial index obtained. If the ankle-brachial index is less than 0.9, a computed tomography (CT) angiogram and vascular surgery consultation is merited.[22][17]

Evaluation

Typically, femoral shaft fractures are readily identified injuries due to thigh deformity and instability; however, occasionally, these injuries are not evident, and further assessment and imaging are required, such as radiographs and CT scanning. Obtunded patients may necessitate more imaging to identify their injuries.

Imaging

X-rays of the chest and pelvis are obtained as part of the advanced trauma life support protocol. When the patient is stabilized, orthogonal radiographs of the suspected injured extremity, including the ipsilateral joints proximal and distal to the injury, should be obtained to characterize the fracture. These images help identify potential fractures to the acetabulum, proximal femur, proximal tibia, and patella and help identify a possible floating knee injury.

CT is typically not the initial imaging modality of the femur, but it is often the first form of imaging obtained in a polytraumatized individual. It has utility in identifying occult injuries and characterizing the fracture for operative planning. Thin-cut imaging can help identify occult femoral neck fractures not seen on standard radiographs. Combined with contrast, vascular lesions can be identified and expeditiously treated.

Classification

Classification of femoral shaft fractures may be descriptive in which the location, type, angulation, shortening, comminution, rotation, and displacement is described. The most commonly used fracture classification system is the Orthopaedic Trauma Association classification because of its high interobserver reliability and accuracy. The system utilizes a coding system to identify the fracture type, resulting in 27 different patterns: 3= femur, 2= diaphysis.[2][23]

32A – Simple

• A1 – Spiral
• A2 – Oblique, angle > 30°
• A3 – Transverse, angle < 30°

32B – Wedge

• B1 – Spiral wedge
• B2 – Bending wedge
• B3 – Fragmented wedge

32C – Complex

• C1 – Spiral
• C2 – Segmental
• C3 – Irregular

The Winquist classification system is mostly of historical significance. It described the cortical comminution and served as a guide on whether to lock the nail and determine weight-bearing status. With the advancement in nailing techniques and nail design, most intramedullary nails are locked, and full weight-bearing is permitted postoperatively.[24]

Treatment / Management

Treatment of femoral shaft fractures can be operative or non-operative. Operative fixation with intramedullary nailing is the gold standard of treatment in high-income countries. Other operative techniques include plate osteosynthesis and external fixation. Closed treatment with traction, splinting, and casting may be temporary treatment or definitive treatment in some third-world countries.

Intramedullary Nailing

Intramedullary nailing (IMN) is the gold standard of treatment for femoral shaft fractures. Early definitive treatment in systemically stable patients within 24 to 48 hours reduces the incidence of pulmonary complications, infection rates, and mortality. Hemodynamically stable patients with multiple injuries received the most benefit from early fixation. Delayed treatment increases pulmonary complications in up to 56% of patients compared to only 16% of patients treated early.[25][26][27] The insertion site of an IMN is outside the zone of injury, preserving the surrounding blood flow and retaining the hematoma that contains beneficial bone growth factors. Intramedullary nailing also has the benefits of early weight-bearing that helps maintain muscle mass, function, strength, and mobility. (A1)

Antegrade Nailing

In the 1940s, Dr Gerhard Küntscher developed the first intramedullary nail. With improved designs, nailing techniques, and locking screws, more complex injuries have been treated with intramedullary nailing. Approaches to nail fixation depend on the patient’s age, body habitus, comorbidities, nail design, and physician preferences. Antegrade nailing is the gold standard treatment of femoral shaft fractures, with excellent outcomes if patients are treated within the first 24 hours. Early fixation decreases pulmonary complications, improves rehabilitation, reduces length of stay, and lowers healthcare costs.[17]

There is debate about the benefits of early fixation in patients with closed-head injuries. Some studies demonstrate an increased incidence of pulmonary complications and central nervous system (CNS) function with early treatment secondary to a second-hit phenomenon of hypoxia and hypotension. Other studies have shown that early fixation does not increase CNS complications; rather, it is the head injury that increases the risk of both CNS and pulmonary complications. However, it is advised to avoid hypoxia and hypotension in these individuals and to consider less invasive treatments in the acute phase of treatment.[28][29][17] (B2)

Approaches include the piriformis, trochanteric, and lateral entry. In the piriformis entry approach, the nail trajectory is along the long axis of the femur, and a straight design nail is used. Disadvantages of this approach include injury to the abductor muscles with resultant Trendelenburg gait and damage to the blood supply to the femoral head. The trochanteric entry technique spares the abductors to a greater degree, and it is easier to establish the starting point. The anterior and lateral bow of the nail accommodates the curvature of the femur. Using a straight nail in this approach risks perforation of the anterior cortex or when the starting point on the greater trochanter is too posterior. The trochanteric entry technique has a reduced operative and fluoroscopic time compared to the piriformis entry technique. Long term functional outcomes are equivalent between the approaches.[30][31](A1)

Retrograde Nailing

Retrograde nailing has recently become more popular. Indications for this technique include the ipsilateral femoral neck, acetabular, tibia fractures (floating knee injuries), bilateral femur fractures, pregnancy, and morbidly obese individuals. Studies have demonstrated comparable outcomes for antegrade nailing. Union (100% vs 99%), malunion (11% vs 13%), and nonunion rates (6% vs 6%) are similar for retrograde and antegrade approaches. A common complaint of retrograde nailing is knee pain, while antegrade nailing is hip pain and stiffness.[32][33] The starting point in this approach is in the middle of the intercondylar notch and 2 to 4 mm anterior to the distal tip of Blumensaat’s line. Despite entering the knee joint, there is no increase in septic knees. Long term, patients may report anterior knee pain or screw irritation distally. Iatrogenic injury to the cartilage and ligaments of the knee is possible.[32][34](B2)

Reaming 

Reaming techniques of the medullary canal provide both mechanical as well as biological benefits to intramedullary nailing. In rat models, reaming did affect the endosteal blood supply, which regenerated in about 12 weeks.[35] Reamings deposited at the fracture site acted as a bone graft containing osteoprogenitor cells and inductive molecules.[36] Reaming decreases the nonunion rate by more than 4-fold, and reamed and locked IMNs have a reported union rate between 97% to 100%, while non-reamed techniques have union rates of 84%.[37] Reaming was once thought to increase the rate of pulmonary complications such as fat emboli syndrome or inflammatory reactions resulting in respiratory compromise. This was considered secondary to the increased pressure that occurs in the femoral canal when instruments or implants are inserted, causing venous embolization of fat. Increased fat in the blood was demonstrated in humans during the procedure, with no increase in pulmonary compromise. Reaming does increase intraosseous bleeding, although there is no increase in postoperative transfusion requirements in patients.[38][39][40] (A1)

Plate Osteosynthesis

Open reduction internal fixation (ORIF) techniques developed in the 1960s were the first operative techniques utilized for fracture fixation. Over time, a better understanding of biological and mechanical processes in fracture fixation was established. ORIF is typically not the primary treatment of femoral shaft fractures unless there is an extension to the proximal or distal femur, which may be a contraindication to intramedullary nail fixation. Plates are used in recalcitrant nonunions, periprosthetic and peri-implant fractures, narrow femoral canals, and open fractures with vascular injury. Open plating techniques require fracture site visualization and significant soft tissue stripping around the fracture site, resulting in interruption of blood flow to the bone, especially the periosteum.[41] Extensive soft tissue dissection may also increase an individual’s inflammatory response to surgery, further complicating care and tissue healing. Minimally invasive techniques such as minimally invasive plate osteosynthesis (MIPO) avoid exposure of the fracture site. The plate is introduced away from the fracture site, positioned submuscularly but above the periosteum, and fixed percutaneously. Bridge plating is a technique that spans an area of comminution with fixation proximal and distal to the affected area.[8] 

External Fixation

External fixation is indicated for patients with open fractures, vascular injuries, polytrauma, stabilization for transfer, and those unstable for early definitive care. External fixators can be applied with minimal effect on the trauma patient’s disease burden. Fixator constructs can vary from surgeon to surgeon, but the governing principles are stable fixation with the relative restoration of length, alignment, and rotation. Neurovascular structures can be avoided by placing pins laterally into the femur rather than from anterior to posterior. Proximal pins can be placed into the femoral neck and head, while distal pins may be placed in the distal femur or proximal tibia. Infrequently, external fixators can be used as definitive treatment if conversion to internal fixation is contraindicated because of medical or other orthopedic problems. Definitive treatment with external fixation has a relatively high complication rate, such as loss of reduction, malunion, pin site infections, osteomyelitis, nonunion, and joint stiffness.[42][43] Treatment with an external fixator is rare because of the successful early treatment with intramedullary nailing.

Traction

First responders at the scene of an accident must quickly assess for any potentially life-threatening injuries. Special attention must be placed on the lower extremities where significant pooling of blood is possible, as discussed earlier. Temporary traction devices such as the Thomas, Hare, Sager, Kendrick, CT-6, Donway, and Slishman splints may be utilized to stabilize apparent femoral injuries. Longitudinal traction applied to the extremity stabilizes the fracture site, restoring the gross length, alignment, and rotation. Traction may also relieve pressure on neurovascular structures and tamponade bleeding by stabilizing the surrounding clot. These devices should be promptly exchanged for fiberglass vs. plaster splint or skin vs skeletal traction in the hospital because prolonged use may cause pressure sores or compress neurovascular structures distally.[44] More tolerable and effective traction systems include skin and skeletal traction that provide better distraction of the affected extremity. Skin traction, also called Bucks traction, is applied through a boot attached to the distal extremity with a counterweight. The problem specific to this technique is a shear injury to the underlying dermal tissue.

In skeletal traction, a pin is placed through the bone distal to the injury, preventing the soft tissues from bearing the traction forces. Common sites of pin placement include the distal femur, proximal tibia, and calcaneus, with the distal femur as the preferred placement because of the superior force vector, better control, and ability to range the knee. In rare cases, skeletal traction may serve as a prolonged treatment in medically unstable patients or as definitive treatment in certain parts of the world. Complications of skeletal traction include pin site infections, iatrogenic neurovascular injury, muscle wasting, immobility, malunion, deep vein thrombosis, and pulmonary embolism.[45] In high-income countries, the preferred treatment is operative fixation resulting in superior outcomes and less morbidity and mortality compared to traction.[46](A1)

Other Considerations

An aging population that aspires to stay active for longer will continue to seek hip and knee replacements, and a growing elderly population will undergo hemi or total hip arthroplasty for femoral neck fractures and cephalomedullary nailing for other proximal femoral fractures. It is projected that by 2040, there will be 1.4 million total hip arthroplasties (284% increase) and 3.4 million total knee arthroplastie4s (401% increase) replacements performed each year.[47] There will be more periprosthetic femoral shaft fractures that will pose new treatment dilemmas and require specialized care. The fracture characteristics and prosthesis design will determine the fixation modality. More invasive open reduction internal fixation may be necessary, placing increased physiologic strain on the patient.

Differential Diagnosis

Injuries to the femoral shaft are typically quite obvious and quickly diagnosed with imaging. It is essential to identify associated bony fractures of the pelvis, proximal or distal femur, and tibia as this will change the treatment. In the context of bisphosphonate use, it is vital to look for hypertrophied lateral cortices bilaterally and identify signs of impending fracture. Patients may present altered or unresponsive and unable to provide an accurate history and physical, resulting in a delay in diagnosis.

Prognosis

Reamed nailing has demonstrated excellent union rates, 100% retrograde, and 99% antegrade, with excellent functional results.[32][33] Patients who undergo early definitive fixation have improved outcomes, fewer complications, and reduced mortality. After intramedullary nailing, patients are allowed to weight bear as tolerated, accelerating their rehabilitation and returning to baseline mobility. Recovery in the elderly population may be slower and often hampered by multiple comorbidities. Patients with bilateral femoral fractures are at an increased risk of mortality in the presence of other injuries and physiologic instability. Isolated bilateral femur fractures (no other injuries) vs bilateral fractures with associated injuries had a mortality of 9.8% and 31.6%, respectively.[48] Patients with unilateral shaft fractures had an overall in-hospital mortality rate of 1.4%. If treatment is delayed greater than 48 hours, the risk of mortality increases 5 times.[49]

Complications

Intraoperative complications include neurovascular injury, iatrogenic fractures, compartment syndrome, thermal necrosis, and malalignment. Postoperative complications include fat emboli syndrome, pulmonary embolism, infection, osteomyelitis, malunion, nonunion, and hip and knee pain. Reaming can cause increased temperatures of up to 57 degrees C resulting in thermal necrosis secondary to enzyme denaturation, potentially leading to delayed fracture healing.[50] In-vivo animal studies have shown that bone necrosis can occur at temperatures of 47 °C with prolonged reaming.[51] 

Nerve injuries are common and can be due to positioning as well as iatrogenic injury. Pudendal nerve injuries occur from positioning patients with a perineal post and have an incidence of 15%.[52] The sciatic nerve can suffer injury in retrograde nailing with excessive traction of the lower extremity or surgical instruments. Vascular injury to the DFA or SFA can occur after penetration with instruments or implants. Despite the use of safe zones for implant insertion, aberrant anatomy can predispose the patient to iatrogenic injury. 

Intraoperative fractures may occur, especially of the greater trochanter, the knee, and perforation of the anterior cortex by the implant. Patients with an abnormally low radius of curvature (increased anterior femoral bow) are at increased risk for anterior perforation.[53][54] Postoperative fractures are most common in areas of stress risers at the ends of an intramedullary nail or plate. Malrotation is one of the most significant complications of long bone fractures, with an incidence of up to 25%. Malrotation of greater than 14 degrees from neutral can alter gait mechanics and efficiency. Patients cope better with internal than with external malalignment.[50] There are several landmarks for assessing rotation, including cortical overlap and comparing the rotation of the lesser trochanter fluoroscopically. Computed tomography of both extremities is the most reliable method to assess rotation.[55] 

Comminuted fractures can present a significant challenge in determining leg length that can manifest as pelvic tilt, leading to hip pain and back pain. In a study of comminuted femur fractures, 6 patients had a leg length discrepancy greater than 1.25 cm, with only 4 of these patients requiring revision surgery.[56] Nonunion is a failure of the fracture to heal or a lack of signs of healing for 6 months. Nonsurgical treatments may include supplementation of vitamin D and calcium and external bone stimulation. Work up would include evaluation for infection as a cause of nonunion. Surgical treatment may include revision fixation with or without bone graft, depending on the cause of nonunion.[57]