Diaphyseal Femur Fracture

Etiology

The femur is divided into the following regions: head, neck, intertrochanteric, subtrochanteric, shaft, supracondylar, and condylar areas. Younger patients are generally involved in high-energy mechanisms, most commonly motor vehicle collisions. Elderly patients can sustain osteoporotic femur fractures from ground-level falls.[1] Another common etiology is gunshot injuries sustained to the lower extremity. Stress fractures can occur in individuals with excess physical activity. Finally, some low-energy femur fractures may be associated with osteoporosis or prolonged use of bisphosphonates.

Epidemiology

An estimated 9 to 22 femur fractures per 1000 people worldwide occur every year. These injuries have a bimodal distribution. Studies show that diaphyseal fractures are often seen in older patients, those with decreased bone density, low body mass index, and extensive anterior and lateral bowing.

Pathophysiology

The femur is the largest bone in the human body. It has an anterior bow with a radius of curvature of 120 cm.[2] Along the posterior middle third of the diaphysis is a raised crest known as the linea aspira, which serves as the attachment site for muscles and fascia and a strut to compensate for the anterior bow. The characteristic deformity following a femur fracture is caused by the strong lower extremity muscles attached to the femur. The proximal fragment is held in flexion and abduction. The iliopsoas attach to the lesser trochanter and provide a strong flexion vector. The gluteus medius and minimus, which attach at the greater trochanter, provide a strong abduction force. The distal fragment is held in varus and extension. The adductors attach at the medial femoral condyle and provide a varus force. The gastrocnemius attaches at the posterior distal femur, pulling the fragment posteriorly and inferiorly and creating an extension deformity at the fracture.

History and Physical

As there may be concurrent life-threatening injuries, assessing the patient’s entire status is important. Upon presentation to the trauma bay, adherence to the advanced trauma life support principles is paramount. If the patient is unstable or if intra-abdominal pathology is suspected, the patient may be transported to the operating room urgently for exploratory laparotomy. It is important to remember that the patient’s life precedes limb. If the patient is stable, performing a thorough physical exam is important. An obvious thigh deformity may be noted. It is important to perform a thorough neurovascular exam, including pulses, and assess for an open fracture. Bilateral femur fractures have been associated with a greater risk of pulmonary complications and increased mortality.

Evaluation

Imaging

Imaging starts with plain radiographs. Orthogonal radiographs of the femur should be obtained. In addition, orthogonal images should be obtained of the hip and knee joints. It is important to assess for ipsilateral femoral neck injuries.  A 1-9% incidence has been noted in the literature. Many level-one trauma centers have adopted protocols to include computed tomography scans, which include both femurs to the level of the lesser trochanter. Before the widespread adoption of these protocols, associated ipsilateral femoral neck injuries were missed approximately 20-50% of the time.[3] Imaging may also play a part in management decision-making. The start site for intramedullary nailing may be compromised in diaphyseal fractures with an associated proximal femur fracture. In these cases, a computed tomography of the proximal femur is helpful to assess the integrity of the greater trochanter or piriformis fossa.

Classification

Open femur fractures can be categorized by the Gustillo-Anderson classification system. Epidemiologic studies documented 43% grade I, 31% grade II and 26% grade III open fractures. Aggressive management is necessary due to the mechanism of injury and the amount of soft tissue that must be violated for a femur fracture to become open. Two common classification systems are used to describe diaphyseal femur fractures.

The Orthopaedic Trauma Association Classification

 32A - Simple

• A1 - Spiral
• A2 - Oblique, an angle less than 30 degrees
• A3 - Oblique, an angle less than 30 degrees

32B - Wedge

• B1 - Spiral wedge
• B2 - Bending Wedge
• B3 - Fragmented Wedge

32C - Complex

• C1 - Spiral
• C2 - Segmental
• C3 - Irregular

Winquist and Hansen Classification

• Type 0 No comminution
• Type I Insignificant comminution
• Type II greater than 50% cortical contact
• Type III less than 50% cortical contact
• Type IV Segmental, with no contact between proximal and distal fragments [4] 

Blood work is always done to assess hemoglobin levels. A femur fracture can cause significant blood loss, which can lead to hypotension. If the wound is open, cultures should be obtained.

Treatment / Management

Open Fractures

In instances of an open fracture, prompt antibiotics should be given in accordance with the facility’s protocol. Weight-based cefazolin is commonly used. Bedside irrigation and debridement should be performed. Operative irrigation and debridement should ideally be performed within 2 hours of presentation.

Ipsilateral Femoral Neck Fractures

In the rare setting of a femoral shaft fracture with an ipsilateral femur fracture, it is recommended that the femoral neck fracture takes fixation precedence.[5] The authors recommend an anatomic reduction of the femoral neck first to decrease the risk of non-union and avascular necrosis of the femoral head. After femoral neck fixation, the femoral shaft fracture is then addressed.   

End of Bed Skeletal Traction

Traction provides the patient with pain control and assists the surgeon with maintaining anatomic length. The strong thigh muscles immediately contract upon injury, causing the shortening of the femur. After radiographic assessment of the knee joint, a traction pin may be placed in the distal femur or the proximal tibia under local anesthesia. For femoral traction, a 4 mm Steinman pin is inserted 2 fingerbreadths above the superior border of the patella to ensure that it is extra-articular. It is placed in the anterior third of the femur to allow passage of the nail if sterile traction is required intra-operatively. For tibial traction, the pin is inserted 3 fingerbreadths distal to the superior aspect of the tibial tubercle. Some have argued against tibial traction due to ligamentous strain and the reported incidence of concurrent ligamentous injury with diaphyseal femur fractures.[6] The pin is often placed to avoid the zone of injury. Twelve pounds (5 kilograms) of traction is applied longitudinally and can be adjusted based on the patient’s weight and muscular tone. The patient notes relief after the thigh muscle fatigue.(B2)

External Fixation

External fixation may be required in the setting of damage control orthopedics.[7] If the patient is hemodynamically unstable and is taken to the operating room for another procedure, it may be prudent to proceed with external fixation. External stabilization may also be indicated in the vascular repair setting. Schanz pins are inserted proximally and distally to the fracture, and traction is applied to approximate length, alignment, and rotation. Some constructs may require the surgeon to span the knee. Studies have shown an approximate 10% infection rate of external fixator pins.[8] Patients with multiple injuries are transitioned to definitive fixation when stable.(B2)

Intramedullary Nailing

IM nailing is the mainstay of treatment for diaphyseal femur fractures. Nailing provides relative stability at the fracture, and the femur heals through secondary bone healing. Fracture fixation with intramedullary nailing can be achieved through an antegrade or retrograde fashion. Retrograde nailing utilizes a start point in the center of the intercondylar notch of the distal femur. Antegrade intramedullary nailing uses 2 distinct start points, the greater trochanter and piriformis fossa starting points.  Trochanteric and piriformis entry nails have been studied extensively, with the consensus of equivalent outcomes.[9] The advantage of using the piriformis entry point is its colinear orientation with the long axis of the femur. This reduces the risk of varus malalignment. The disadvantage of this starting point is the technical skill needed to establish this point, especially in obese patients.[10] This entry point puts the piriformis muscle insertion at risk of iatrogenic injury, resulting in an abductor limp. Pediatric patients also have an increased risk of avascular necrosis of the femoral head. The greater trochanter entry point offers the advantage of reduced risk of injury to adductors, and it is less technically demanding and is a more appropriate option for obese patients. The disadvantage to the greater trochanter entry point is that it is not colinear with the axis of the femur. This mismatch necessitates using an intramedullary nail specifically designed for this entry point to avoid varus malalignment.[10] Regarding nail design, the radius of curvature of the intramedullary nail must match the radius of curvature of the patient's femur.[2] An intramedullary nail with a radius of curvature greater than that of the patient's femur (ie a straighter nail), can cause perforation of the anterior cortex of the femur during insertion. Patients may generally be made weight-bearing as tolerated following intramedullary nailing.(B2)

Submuscular Plating

Submuscular plating is generally relegated to complex or peri-prosthetic fractures in which the start site is compromised or unavailable due to a separate implant. A lateral plate can be applied through a vastus splitting or sub-vastus approach. Weight-bearing is generally protected after plating.

Timing of Surgery

It is recommended that femur fractures be managed within 2-12 hours after injury, provided the patient is hemodynamically stable. Studies show significant benefits when intervention is undertaken within the first 24 hours. Immediate fixation lowers pulmonary complications, decreases mortality, and avoids long ICU stays. However, the type of fixation remains debatable.

Differential Diagnosis

In patients with a femoral shaft fracture, an ipsilateral femoral neck fracture must be ruled out. Depending on the mechanism of injury, patients may have a variety of concomitant injuries. In a high-energy scenario, compartment syndrome must be ruled out. In patients with a low-energy mechanism, the fracture may be caused by a pathologic process due to neoplasm or metabolic derangement, in which case a thorough workup is warranted. 

Prognosis

The prognosis of patients with diaphyseal femur fracture varies on age, comorbidity, presence of osteoporosis, and type of treatment. Intramedullary nailing has good results, but a significant number of patients require the removal of hardware in the future because of pain. Deaths after surgery in elderly patients are not uncommon. Other complications include infection, blood loss, nonunion, delayed union, malunion, and the need for repeat surgery. External fixation is effective but is also associated with pin infections and angulation problems. Patients also need prolonged stay in the hospital, followed by extensive rehabilitation. Gait problems and pain continue to be present in a significant number of patients.

Complications

Non-unions are rare but do occur.[11] In these instances, the root of the non-union must be established. Revision surgery can be pursued when a specific aspect of fixation, such as stability or biology, is to be addressed. Hypertrophic, aseptic non-unions can be addressed with compression and exchange nailing.[12] In atrophic non-unions, infection must be ruled out, especially in the setting of previously open fractures. The patient’s nutrition status must be assessed with labs. Revision of atrophic non-union is often supplemented with bone grafting. Deaths related to deep vein thrombosis/pulmonary embolism, infection, nerve injury, and compartment syndrome are not uncommon.