The femur is the longest and strongest bone of the body, and it carries the weight of the entire body. It is the heaviest tubular bone of the body that requires high-energy force to fracture, for example, as from motor vehicle accidents. Fracture of the femur carries high-risk complications like hemorrhage, fat embolism, and infection. Inappropriate management of femur fracture can also cause prolonged morbidity with shortening, misalignment, and deep venous thrombosis (DVT). The annual incidence of midshaft femur fracture is approximately 10 per 100,000 person-years. The incidence of femoral diaphyseal fractures follows a bimodal distribution that peaks in young adults and the elderly, secondary to high-energy mechanisms in the young and low-energy falls in the elderly with decreased bone density. Emergency medical service (EMS) personnel should immobilize the femur to prevent further injury during transport. Traction splints are recommended on all mid-shaft femur fractures to establish patient comfort and better fracture alignment. Traction splints have utility in the management of both closed and open fractures of the femoral diaphysis. They are designed to provide temporary stabilization at the scene for transport to the hospital for definitive treatment/management. Traction splints are a temporary form of immobilization, as prolonged use of traction splints can cause pressure sores.
The diaphysis of the femur has a normal anatomic alignment that is 5 to 7 degrees from the physiologic axis of the femur, which can be drawn from the center of the femoral head to the center of the knee. The normal femur exhibits an anterior bow, providing flexibility to withstand large amounts of axial force.
The determination of displacement seen in femur fractures is by the pull of the muscles proximal and distal to the fracture. Fractures of the diaphysis typically will result in external rotation of the proximal segment due to the pull of the external rotators and abductors such as the gluteus medius, and internal rotation of the pull of the adductor complex.
While injuries to surrounding nerves are rare in diaphyseal femur fractures, the femur does have a robust blood supply, which can lead to large amounts of blood loss. The large compartments of the thigh can hold up to 3 liters of hemorrhaged blood. A patient with a femur fracture can be expected to lose about 1 TO 1.5 liters of blood or up to 30% of the normal body's blood volume. Therefore, medical personnel must keep a close eye on the hemodynamic status of patients with a suspected femur fracture.
A suspected or obvious isolated fracture of the midshaft femur is an indication for traction splint. If there are other fractures in the foot or ankle traction may not be effective, because traction splints require support on strap sites to be able to apply traction.
Clinical diagnosis is usually obvious from mechanism, pain, swelling, and deformity/shortening of the thigh. Extreme pain may mask these secondary injuries. Since most of the femur fracture occurs with high energy trauma, pelvic ring, hip, groin, perineum, and buttock evaluations are crucial. Up to 40% of the femur fractures are associated with an ipsilateral knee injury.
The clinician should asses distal pulses (popliteal, dorsalis pedis, posterior tibialis) with capillary refills on the ipsilateral toenails. If there is a concern for malperfusion of the extremity, an ankle-brachial index (ABI) can help to evaluate for blood supply. A decreased ABI compared to the contralateral extremity is an indication for a CT angiogram to further assess for vascular injury. Vascular injury resulting in malperfusion of the extremity is a surgical emergency.
Neurologic injury with isolated femoral diaphysis fracture is rare, but a careful motor and sensory assessments are important. A standard neurovascular exam of the extremity distal to a femur fracture should include a sharp and light subjective sensation of the sural, saphenous, superficial peroneal, deep peroneal, and tibial nerves. Examiners should assess for dorsiflexion and plantarflexion of the ankle and great toe. In a presumed femur fracture, assessment of the motor function of knee flexion and extension will be limited, but a brief ligamentous examination is appropriate. One should not miss signs of gross knee instability or knee dislocation, which carry a very high association with an acute neurovascular injury that may require urgent surgical intervention and stabilization.
Commonly used tractions are Thomas, Hare, Sager, Kendrick, CT-6, Donway, and Slishman traction splints. We will discuss the most common Traction splints: Hare, Sager
Hare Traction Splints
In the 1960s, Glen Hare developed Hare traction splint, modifying full ring Thomas splint into half-ring splint by incorporating a ratchet mechanism with additional length adjustment mechanisms and improving the ischial pad. It maintained bipolar traction with two steel rods on both sides of the limb. Most importantly, the Hare traction splint was more compact, easy, and effective for a femur fracture. The Hare splint is not effective with proximal femur shaft fracture because the ischial pad may rest directly under the fracture. An adult unit is not adjustable for pediatric patients. Below is a simplified application guide.
Sager Traction Splints
In the 1970s, Joseph Sager and Dr. Anthony Borshneck developed the Sager splint. Sager traction is unipolar traction. One steel rod sits between a patient's legs and applies traction from the ankle with counter pressure directed onto the ischial tuberosity. Sager splint sits between the leg against the ischial tuberosity, so it is more effective for proximal femur fracture than hare splint. Also, one Sager splint can be used for a bilateral femur fracture. However, there is an increased risk of damage to the genitalia as the splint can move from the initial ischial tuberosity placement during transport. Sager traction splint can measure the actual traction applied on the gauge. The optimal traction is roughly 10% to 15% of a patient's body weight.
After initial evaluation in the hospital, it is appropriate to transition the patient to skin traction, commonly referred to as "Bucks Traction," or skeletal traction if necessary. Bucks traction has the advantage that it requires no incision and is far less traumatic for the patient, but is limited in the amount of weight that is safe without causing skin breakdown. Any form of skin traction, whether Bucks traction or with traction splints, has the risk of overlying soft tissue damage. The amount of weight and traction applied to the skin should never result in wounds or soft tissue damage, for which the clinician must be vigilant.
Traction splint is a useful emergency tool to align the femur fracture better, increase arterial blood flow, decrease pain and spasm, and reduce the risk of further injury from fractured bone fragments.
If the patient is not stable, do not waste time trying to apply traction splint at the scene. Splint the injured leg against the uninjured leg to expedite the transport.
Frequently re-assess neurovascular function of the extremity after the application of splint and during transport.
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