Diaphyseal femur fractures are commonly encountered in association with other high-energy injuries. These injuries can lead to life-threatening sequelae. Prompt intervention and thoughtful management lead to the best patient outcomes.
Younger patients are involved in high-energy mechanisms, most commonly motor vehicle collisions. Elderly patients can sustain osteoporotic femur fractures from ground level falls. Another common etiology is from gunshot injuries sustained to the lower extremity.
There are an estimated 9 to 22 femur fractures per 1000 people worldwide that present every year. These injuries present in a bimodal distribution.
The femur is the largest bone in the human body. It has an anterior bow with a radius of curvature of 120 cm. Along the posterior middle third of the diaphysis, there is a raised crest known at 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 which are attached to the femur. The proximal fragment is held in flexion and abduction. The iliopsoas, which attaches at the lesser trochanter, provides 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.
As there may be concurrent life-threatening injuries, it is important to assess the patient’s entire status. 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, it is important to perform a thorough physical exam. 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.
Imaging starts with plain radiographs. Orthogonal radiographs of the femur should be obtained. In addition, orthogonal imaging 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.
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 CT of the proximal femur is helpful to assess the integrity of the greater trochanter or piriformis fossa.
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 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
32B - Wedge
32C - Complex
Winquist and Hansen Classification
In instances of an open fracture, prompt antibiotics should be given in accordance with the facility’s protocol. Weight-based cefazolin is commonly used. A bedside irrigation and debridement should be performed. Operative irrigation and debridement should ideally be performed within 2 hours.
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 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 two 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 in the event sterile traction is required intra-operatively. For tibial traction, the pin is inserted three 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. Most often, the pin is simply placed to avoid the zone of injury. Twelve pounds of traction is applied in a longitudinal fashion and can be adjusted based on patient’s weight and muscular tone. Relief is noted by the patient after the thigh muscles fatigue.
External fixation may be required in the setting of damage control orthopedics. 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 also may be indicated in the setting of vascular repair. 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. Patients with multiple injuries are transitioned to definitive fixation when stable.
Intramedullary 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. Though the fracture may not be reduced anatomically, length, alignment, and rotation of the anatomic femur are obtained.
Obtaining an accurate start site is imperative to a successful operation. Trochanteric and piriformis start site nails have been studied extensively, with the general consensus of equivalent outcomes.
Patients may generally be made weight-bearing as tolerated following intramedullary nailing.
Submuscular plating is generally relegated to complex or peri-prosthetic fractures in which the start site is compromised or not available 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.
Non-unions are rare but do occur. In these instances, the root of the non-union must be established. Revision 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. 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.
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