Biomechanics and Treatment of Femoral Shaft Fractures

Biomechanics and Treatment of Femoral Shaft Fractures

Femoral shaft fractures are high-energy injuries to the femur that can result in life-threatening injuries, such as pulmonary and cerebral injuries, as well as ipsilateral femoral neck fractures. Here's what you need to know about their diagnosis, treatment, and prognosis:

Mohammad Hutaif ( ORCID ID: 0009-0001-1092-5600) via Google Scholar.
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Summary

Femoral shaft fractures are diagnosed radiographically with radiography of the femur and the hip to rule out coexisting femoral neck fractures. Treatment generally involves intramedullary nailing, which is associated with >95% union rates.

Epidemiology

Incidence: Common, with an incidence of 37.1 per 100,000 persons annually

Demographics: Fractures are most common in younger patients and are often a result of high-speed motor vehicle accidents. Low-energy fractures are more common in the elderly and are often a result of a fall from standing. Gunshot fractures can also occur.

Etiology

Mechanism: Traumatic and high-energy. Fracture patterns can include transverse, spiral, oblique, segmental, and comminuted fractures. Associated orthopedic injuries include ipsilateral femoral neck fracture (with an incidence of 2-6%), bilateral femur fractures, ipsilateral tibial shaft fractures, and ipsilateral acetabular fractures.

Associated systemic injuries: These may include thoracic injuries such as pulmonary injury (which can lead to acute respiratory distress syndrome if early surgical treatment of the femur fracture is performed) and cerebral hemorrhage, subdural hemorrhage (which can be exacerbated by early surgical treatment of the femur fracture and intraoperative hypotension).

Anatomy

Osteology: The femur is the largest and strongest bone in the body. The anterior bow of the femur accommodates the musculature that surrounds it. The femoral canal runs down the length of the bone and protrudes anteriorly, forming the linea aspera. The femoral neck and subtrochanteric region are prone to fractures due to a high percentage of trabecular bone and poor blood supply.

Muscles: The thigh has three compartments; the anterior, posterior, and adductor. The muscles of the compartments act as a deforming force after the fracture of the femoral shaft. The proximal fragment is abducted and flexed by the gluteus medius, minimus, and iliacus muscles. The distal fragment is subject to varus forces by the adductor muscles and extension forces from the gastrocnemius.

Biomechanics: The femur is subject to pure bending, rotational, uneven bending, and four-point bending stresses depending on the fracture location and mechanism of injury.

Classification

Winquist and Hansen Classification: This classification system is based on the amount of comminution, with Type 0 fractures being those with no comminution and Type IV fractures being segmental fractures with no contact between the proximal and distal fragment.

AO/OTA Classification: This classification system is based on the type of fracture wedge involved and is divided into three groups: Simple (32A), Wedge (32B), and Complex (32C).

Presentation

Initial evaluation: Advanced Trauma Life Support (ATLS) should be initiated, with adequate resuscitation and normal vital signs. Initial presentation can include pain in the thigh and a tense, swollen thigh. Blood loss in a closed femoral shaft fracture can range from 1000-1500ml, and it is 500-1000ml in a closed tibial shaft fracture. On examination, there may be tenderness about the thigh, and it may be difficult to examine for an ipsilateral femoral neck fracture due to pain from the femoral shaft fracture.

Imaging

Radiographs: The recommended views include AP and lateral views of the entire femur and the ipsilateral hip to rule out coexisting femoral neck fractures. CT scan may be used to rule out associated femoral neck fractures.

Treatment

Nonoperative: Long leg or hip spica casting can be done for non-displaced fractures that are length-stable, or for pediatric patients with multiple medical comorbidities.

Operative: Antegrade or retrograde intramedullary nailing is the gold standard for treatment. External fixation can also be used in unstable polytrauma victims or as a provisional fixation in severe open fractures.

Complications

Complications that may occur include heterotopic ossification, pudendal nerve injury, femoral artery or nerve injury, malunion and rotational malalignment, delayed union, nonunion, infection, and weakness.