Femoral shaft fractures — Musculoskeletal Medicine for Medical Students — OrthopaedicsOne

Femoral shaft fractures.
Description.
Femoral shaft fractures are emergent injuries that are typically a result of high energy forces or low energy falls in the elderly and are commonly associated with multisystem trauma. Because the femur is a major load-bearing bone and is the biggest in the body, untreated or inappropriately treated fractures may cause lifelong morbidity and substantial disability.
Structure and function.
The femur is the longest and heaviest bone in the body and as such, requires an extensive blood supply. Due to this large blood supply, mainly from the nutrient arteries branching off of the profunda femoral perforating arteries, fractures tend to heal relatively well. However, fractures commonly produce significant blood loss.
The large size of the femur has advantages in load bearing, but with it comes an increase risk of fat embolism.
The femur is well protected with powerful muscles. This protects the femur from most forces; however, it makes reduction difficult and causes serious fracture displacement. The chief muscular deforming forces depend on the fracture site and are:
Adductors: adduct the distal fragment Abductors (gluteus medius and gluteus minimus): abduct the proximal fragment Iliopsoas: flexes and externally rotates the proximal fragment Fascia lata: resists the adductors Gastrocnemius: flexes the distal fragment.
A picture like this: “ FIGURE 41-3. Deforming muscle forces on the femur; abductors (A), iliopsoas (B), adductors (C), and gastrocnemius origin (D). The medial angulating forces are resisted by the fascia lata (E). Potential sites of vascular injury after fracture are at the adductor hiatus and the perforating vessels of the profunda femoris.” From: http://anatomedunesa.weebly.com/uploads/1/8/7/1/1871495/fractures_of_the_shaft_of_the_femur_-_surgical_anatomy.pdf.
Epidemiology.
Fractures of the shaft of the femur show a bimodal distribution pattern with more common incidence in people 65. They occur in about 1 in 10,000 people per year.
Clinical presentation.
Patients will usually present after high-energy trauma such as motor vehicle accidents, pedestrian/vehicle accidents, or gunshot wounds. They can also be seen in the elderly after a fall. The injury should be apparent. Patients will be in significant pain and unable to bear weight. There will be abnormal mobility at the fracture site. The leg will often be swollen, externally rotated, abducted, and shortened.
Femoral shaft fractures are seldom seen without other associated injuries, so it is important to look for systemic trauma. These fractures do not usually produce clinically significant hypotension, so if encountered, look for bleeding elsewhere.
Unlike adults, femoral shaft fractures in children are often from a torsional load, which results in spiral patterns. Harsh deliveries, especially from the breeched position, sometimes result in femoral shaft fractures. In cases of unexplained femoral fractures, child abuse must be considered.
It is very important to exclude concomitant ipsilateral fractures of the patella, femoral neck, and dislocations of the hip. Femoral neck fractures should take precedence over the shaft fracture because of the scant blood supply and consequent risk of avascular necrosis. Knee ligament injuries are also commonly associated with shaft fractures. Stability should be assessed after fracture stabilization.
Thigh compartment syndrome is rare but can be seen upon presentation or after IM fixation. This is treated by immediate fasciotomy.
Serious complications include Fat embolism syndrome (FES) and acute respiratory distress syndrome. Early fracture stabilization is a deterrent.
In any instance where the mechanism was low energy, pathologic etiology should be investigated.
Femoral fractures often present with multisystem trauma so always check the patient’s airway, breathing, and circulation! Address the extremity injuries secondarily to the more centralized injuries.
Do not underestimate the amount of blood loss! It is common to have up to 3 units of blood loss into the soft tissue compartments. Sufficient fluid resuscitation is crucial.
While compartment syndrome is rare, the compartments must still be evaluated.
A proactive investigation of ipsilateral femoral neck fractures is necessary. A miss here would be devastating to the patient.
Get a baseline chest x-ray. You should always be suspicious of fat embolism syndrome (FES) and acute respiratory distress syndrome (ARDS). FES typically occurs 24-72 hours after the traumatic event. The classic triad associated with FES is:
Respiratory changes (fat emboli damage small vessel perfusion with resulting damage to the pulmonary vascular bed) Neurological abnormalities (cerebral embolism) Petechial rash (embolization of small dermal capillaries)
Images of Fat Embolism Syndrome like this one: http://www.nejm.org/doi/full/10.1056/NEJMicm1006177http://www.nejm.org/doi/full/10.1056/NEJMicm1006177 http://www.nejm.org/doi/full/10.1056/NEJMicm1006177 So look for dyspnea or tachypnea, confusion, hypoxemia, and petechial rash. The petechial rash is pathognomonic for FES. FES may progress to ARDS.
Differential diagnosis.
In up to 9% of femoral shaft fractures, there is an associated ipsilateral femoral neck fracture. 20%-50% of those are initially missed, so a proactive investigation of ipsilateral femoral neck fractures should be performed. There are ipsilateral knee injuries in 20%-40% of patients and ipsilateral tibial fractures in approximately 10% of cases. It is recommended to evaluate the femoral neck with a CT scan and an x-ray of the hip with internal rotation.
I would like an image like the one above that shows an x-ray of the shaft and neck with a ct of the fractured neck: taken from http://olc.metrohealth.org/SubSpecialties/Trauma/Media/SkeletalTrauma/ch52.pdf.
Objective evidence.
The core of femoral shaft fracture diagnosis is the x-ray, including AP and lateral views of the adjacent joints (i.e. a joint above and joint below). This includes the hip and the knee. It is recommended to evaluate the femoral neck with a CT scan and an x-ray of the hip with internal rotation to prevent missing an ipsilateral femoral neck fracture. Depending on the amount of trauma, an entire trauma series may be needed. A baseline chest x-ray may be helpful for later comparison and diagnosis of a fat embolism. A hemoglobin and hematocrit level should be ordered and tracked because of the potentially large amount of blood loss. However, this usually does not cause significant hypotension. If encountered, look for bleeding elsewhere.
Fractures are described according to their location (e.g. proximal, middle, and distal thirds), pattern (e.g. comminuted, spiral, oblique, or transverse), and degree of comminution. The main classification systems are the AO system and the Winquist system.
Fractures can occur anywhere along the shaft, with an incidence rate that is very similar for the upper, middle, and lower thirds. Because of the strong muscular attachments of the quadriceps and hamstrings, displacement often occurs as angulation and overlap. When the bone breaks the muscles contract pulling the bone ends past each other producing further blood loss, pain, soft tissue, vascular and nerve damage. Often times muscle will be wedged in between the fracture fragment.
Risk factors and prevention.
Driving safe and wearing a seatbelt are the obvious ways of preventing these injuries. Beyond this, there is not much else that one can do to avoid high energy trauma. In the elderly, diligent use of walkers (if needed) and strengthening and stability exercises may decrease the risk of falls.
Treatment options.
The goals of treatment no matter the operative or nonoperative technique are restoration of length, axial alignment, and rotation.
ATLS protocol should be followed due to the high association with systemic trauma. Early reduction and stabilization is a must to prevent pulmonary complications (ARDS, pneumonia, and fat embolism). The type of fixation does not seem to matter as much as the amount of time until stabilization.
Due to the risk of non-union and avascular necrosis, associated femoral neck fractures should take precedence over treatment of the shaft.
Operative treatment with internal fixation using intramedullary nailing and interlocking screws is the current treatment of choice for most femoral shaft fractures. It allows for early mobilization, which outweighs the small chance of infection. It promotes early muscle activity and functional recovery, which decreases cardiovascular, pulmonary, and joint stiffness complications.
Conservative treatment is only used in incidences where the patient is inappropriate for surgery. It involves traction, manipulation, and support via traction splint (e.g. Thomas splint). The results of conservative treatment are good, but the period of disability and length of hospital stay are much longer than with non-conservative treatment. Thus, nonoperative treatment may be cost prohibitive.
External fixation is reserved for contaminated open fractures that cannot be sufficiently debrided or temporarily used for damage control orthopedics in patients who are too unstable for permanent intramedullary fixation. It affords extra time to stabilize the patient and treat the more life threatening injuries.
Rehabilitation exercises are essential for proper healing. Exercises for the lower leg and foot should be started early to prevent loss of muscle tone and deformity. Flexion and extension exercises of the knee should start as soon as the pain begins to settle.
Outcomes vary greatly because of the other trauma associated with these injuries. The treatment results of isolated shaft fractures are excellent with nearly 100% union, but as with any surgery there are potential complications. These include infection, malunion, delayed union, non-union, and pain from hardware. The rates of these complications are very low but can increase with open fractures and non-isolated fractures.
Knee stiffness is a common complication. This can be caused by quadriceps tethering, which can lock the patella in place. Fractures closest to the knee create the most problems with quadriceps tethering. Knee stiffness can also be caused by prolonged immobilization. Hence, the need for early mobilization and physical therapy.
Bilateral shaft fractures more than double the risk of mortality.

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