Femoral shaft fractures

Introduction

Fractures of the femoral shaft can occur as a result of high energy trauma or low energy falls in osteoporotic patients. The bimodal distribution peaks at 25 and 65 years of age with an overall incidence of approximately 1 per 10,000 people per year. Motor vehicle accident is the most common cause, followed by pedestrian versus automobile, falls from height, and gunshot injuries.

Anatomy

The femoral shaft is the region starting 5 cm distal to the lesser trochanter and ending 9 cm above the knee joint.

Classification

Femoral shaft fractures can be classified with the Winquist classification or the AO/OTA classification. The Winquist classification is based on the amount of comminution. Type I represents a femoral shaft fracture with no comminution or a small butterfly fragment less than 25% of the bone. Type II is a comminuted femoral shaft fracture with a butterfly fragment 50% or less of the width of the bone. Type III is comminuted with a large butterfly fragment greater than 50% of the width of bone. Type IV is severe comminution of an entire segment of bone. Type V is a fracture with segmental bone loss.

The OA/OTA classification gives this fracture a 32 designation as the femur is considered the third bone, and the midshaft is considered the second segment. Type A is a simple fracture pattern (transverse, spiral, or short oblique). Type B is a small butterfly or bending wedge fragment. Type C has segmental comminution.

Presentation

Patients often present with deformity and swelling of the thigh. They are often transported to the emergency room in skin traction. Although loss of 2-3 units of blood is possible from femoral shaft fractures, hypotension and shock do not often present in young, healthy patients with isolated unilateral femoral shaft fracture. Hypotension and signs of shock in this patient requires a search for another cause. Symptoms of concomitant injuries (head, thorax, spine, etc) should be elicited if present.

Diagnosis

Most femoral shaft fractures are high energy injuries, and thus often are accompanied by other injuries (head, thorax, spine, etc). The patient's survival may depend on the expedient diagnosis of these concomitant injuries.

The skin of the thigh should be examined for open fractures of the femur immediately. Nerve and vascular function should be assessed. Arterial injury should be assessed by palpation of the distal pulses and obtaining an objective measure using ankle brachial index (ABI). In one study, 94% of ABI's less than 0.90 were accompanied by angiographic evidence of vessel injury, and 100% of ABI's greater than 0.90 had no evidence of vascular injury (Johansen, JOT, 1991). The ligamentous structures of the knee should be examined for stability as clinically significant knee ligamentous injuries occur in 20-30% of femoral shaft fractures.

Fractures elsewhere in the femur or acetabulum, including femoral neck fractures, should be suspected and investigated. Two to six percent of femoral shaft fractures also have femoral neck fractures. The initial evaluation of a trauma patient with a femur fracture should include radiographs of the chest, AP pelvis, hip, and knee. If any concern for a femoral neck or acetabular fracture exists, a CT should be performed to rule these out. A secondary survey for symptoms and signs of fractures throughout the body should be performed and pertinent radiographs should follow. It is extremely important to rule out injuries that can alter the surgical plan. A femoral neck fracture can be displaced significantly if put on a fracture table, and treatment after anterograde nailing of the femur can be difficult. An unstable pelvic injury should not be placed on a fracture table for fixation of a femoral shaft fracture.

Treatment

The goal in surgical treatment of femoral shaft fractures is to restore length, alignment, and rotation to the femur. The standard treatment of femoral shaft fractures in adults is an anterograde, reamed, locked intramedullary (IM) rod. However, there are several relative indications for retrograde IM rod insertion. These include morbid obesity, pregnancy, ipsilateral femoral neck fracture, bilateral femur fractures, skin about the hip which is unsuitable for insertion of an anterograde rod, floating knee, and ipsilateral acetabular fracture. Numerous studies have compared reamed anterograde to reamed retrograde nailing. Although controversial, it seems that both have high union rates that are not statistically different (Ricci, JOT, 2001). Retrograde nailing results in more knee pain, and anterograde nailing results in more hip pain (Ricci, JOT, 2001; Tornetta, JBJS Br, 2000).

Plate fixation is typically reserved for specially circumstances such as open growth plates, ipsilateral femoral neck fractures, and use for corrective osteotomies.

External fixation can be utilized for contaminated open femoral shaft fractures, fractures in the presence of severe vascular injury, or in unstable patients with significant polytrauma in which femoral nailing could be detrimental (hypotensive patient with traumatic brain injury).

Traction is a non-operative option, although prolonged immobilization, knee stiffness, and malunion are complications. Typically, 8-10 weeks of traction is required prior to mobilization. Traction is occasionally used to treat pediatric femur fractures. For the most part, traction is of historical significance in adults, although it may be the best option in the patient who cannot tolerate surgery.

Complications

Complications of femoral shaft fractures include:

Malunion (5-10%) with rotation >20 degrees requiring revision
Nonunion (95-100% with reamed, canal-fitting implants)
Infection
Fat emboli syndrome, characterized by hypoxia, mental status changes, and skin petechiae (Gurd, Br J Surg, 1969), is not common but can result in significant morbidity and mortality.
Compartment syndrome risk increases with coagulopathy, vascular, and crush injuries
Hip pain with anterograde and knee pain with retrograde rods
Deep vein thrombosis (DVT)

Red Flags and Controversies

Anterograde vs retrograde

It seems that both have high union rates that are not statistically different (Ricci, JOT, 2001).
Retrograde nailing results in more knee pain, and anterograde nailing results in more hip pain (Ricci, JOT, 2001; Tornetta, JBJS Br, 2000).

Piriformis vs greater trochanteric entry nails (the following information was obtained from Josh D. Auerbach MD, UPenn Trauma Conference, 1/28/2008)

Level I evidence suggests no differences between piriformis and greater trochanteric entry ([Starr, JOT,2006|http://www.ncbi.nlm.nih.gov/pubmed/16721238?ordinalpos=4&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum]).
Level II evidence suggests slight advantage in favor of greater trochanteric with respect to operative times and fluoroscopic times, the differences in which were even more pronounced in obese ([Ricci, JOT, 2006|http://www.ncbi.nlm.nih.gov/pubmed/17106375?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum]).
Based on evidence available, both systems are safe and effective; the decision to use piriformis or greater trochanteric-entry should be left to surgeon familiarity and comfort.

Reamed vs unreamed

Reaming decreases the major endosteal blood flow to the cortex.
Reaming theoretically decreases lung function and can lead to adult respiratory distress syndrome (ARDS), especially in the multiply injured patient.
Some studies show detrimental respiratory effects of reaming within 24 hours of injury (Pape, JOT, 1997).
Some studies show increased incidences of ARDS if femoral nailing was delayed >24 hours (Johnson, JOT, 1985).
Other studies suggest that the pulmonary injury itself, and not the presence, treatment, or timing of treatment of the femoral shaft fracture, was the major determinant of morbidity and mortality (Bosse, JBJS Am, 1997; Brundage, JOT, 2002; Johnson, JOT, 1985)
Reaming allows the femur to accommodate a larger nail (stronger construct with less fracture motion) and creates a tighter interference fit at the fracture site.
Compared to unreamed nails, higher union rates and lower incidence of revision have been found in reamed nails (Tornetta, JOT, 2000).

Outcomes

Results are heavily dependent on associated injuries. Isolated femoral shaft fractures treated with IM rods do well with approximately 100% union, <1% infection, and <10% incidence of malunion. Femoral shaft fractures in multiply injured patients also show increased rates of union; however, rates decrease for open injuries and fractures with segmental loss. Infection also increases to 10% in high grade open injuries.

External fixation for definitive treatment results in increased rates of pin tract problems, malalignment, knee stiffness, delayed union, and nonunion.