Anatomy
Introduction
Cause
Symptoms
Diagnosis
Treatment
Complications
The musculoskeletal system of children is different from that of an adult and the progressive increase in bone strength of the paediatric bone explains the difference in etiologies of femoral shaft fractures at different age groups. Femoral shaft fracture peaks in the early childhood and adolescence. This bimodal distribution is attributable to the thin bone cortices and the relative weak woven bone in the early childhood and the increase incidence of high energy trauma in the adolescence.
Femoral shaft fracture represents approximately 1.5 to 2% of all bony injuries in children. Due to the characteristics of growing bone; varying causes of the femoral fracture can be found in children at different ages. Occasionally, it may occur as a result of birth trauma. It is a temporarily disabling injury to children.
While most femoral shaft fractures are attributed to trauma, other possible pathologies should be excluded. Conditions predisposing to low bone mineral content such as osteogenesis imperfecta, renal diseases, neuromuscular disorders, neoplasms, etc, are to be excluded before any treatment plan. Fracture found at birth may be an intrautero fracture or resulted from some form of birth trauma due to difficult delivery. It could associate with some congenital connective tissue abnormalities, such as osteogeneis imperfecta. Pathologic femoral fractures are relatively rare in children. Child abuse must also be considered, especially in children younger than 1 year old.
With a femoral shaft fracture, a baby will stop moving the affected limb while a child will be unable to walk. They are usually in extreme pain and agitated. Swelling, instability, crepitus (a popping cracking sound and sensation felt under the skin) may be present at the site of injury.
The diagnosis of paediatric femoral fracture is usually not difficult and a physical examination is necessary to document the presence of the fracture as well as to exclude multiple system injury. X-ray evaluations are generally sufficient for the diagnosis and should include the entire femur, adjacent hip and knee joints. Femoral fractures are classified based on their pattern, degree of comminution and soft tissue disruption. They could be transverse, spiral or oblique and this may affect the choice of the definitive treatment. Magnetic resonance imaging, computerized tomography or bone scan are sometimes necessary for evaluation of the underlying pathologies.
Treatment of paediatric femoral shaft fractures and the healing rate is age dependent. In general, nonunion is rare and the fracture could heal even with wide displacement, followed by remodeling. Treatment modalities include the Pavlik harness (a specially designed splint), traction, hip spica, and external fixation etc. Internal fixation such as plating, flexible nailing or intramedullary nailing can be considered for older children in order to promote ambulation and rehabilitation.
Non-surgical treatment is usually adequate for younger children whereas operative treatment may be more suitable for adolescence. However, treatment should be tailored to the individual clinical situation, fracture characteristics, family situation and economic concerns.
The capacity of children’s bone to remodel significantly affects the management of the paediatric femoral shaft fractures and provides satisfactory clinical result even with different treatment modalities. The most common sequela after paediatric femoral shaft fractures is leg length discrepancy. Overgrowth is common after the fracture. Residual angular, torsional deformity may also occur. Nonunion or delay union is rare and neurovascular complication is uncommon after the injury. The younger the patient, the more effective the remodeling potential with growth and the less likelihood of complications will be.
Dr. CHAN, Wai-lam