This module examines how the pediatric skeleton differs from the mature skeleton and relates these to common injury patterns seen in children, treatment choices and expected outcomes.
Objectives
Upon completion of this module, the student will be able to:
Describe the unique characteristics of the pediatric skeleton
Discuss common pediatric fracture types
Identify and propose treatment for commonly encountered pediatric fractures
List fracture complications unique to children
References
Lawrence, P., Essentials of Surgical Specialties, 2nd edition, p. 299-316
Chapter 1 – Skeletal Growth and Development as Related to Trauma in Green: Skeletal Trauma in Children, 3rd ed., Elsevier. (Available via MDConsult which is free with current CMA membership).
The pediatric skeleton changes considerably from birth to adulthood. It is important to understand the unique characteristics of pediatric bone in order to plan treatment of skeletal injuries in children. Review Chapter 1 in Skeletal Trauma in Children (3rd edition, ed. Green). As you do so, identify the unique anatomic, biological and biomechanical features of the pediatric skeleton. It may be helpful to summarize this as a table. Once you have done this, work through the cases and questions on the next few web pages.
The pediatric skeleton is characterized by unique anatomic features. These include:
A strong, thick periosteum layer covering bone,
Increased osteoblastic activity because of growth,
The presence of growth plates (physes) at the end of long bones and at areas of musculo-tendinous attachment (apophyses - two common sites are the tibial tubercle and the pelvic iliac crest).
Give examples of three clinical correlates to the features listed above:
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The intact posterior periosteal hinge in this supracondylar humeral fracture will help achieve a satisfactory closed reduction in this child. If the posterior periosteum is torn (as it is anteriorly) the fracture will be much more unstable and may require open reduction.
The periosteum may increase stability and reduces displacement in some pediatric fractures. If an intact periosteal "hinge" remains (usually on the compression side of the fracture), it can be used to aid in closed reduction.
In general, children's fractures heal more quickly than equivalent adult injuries. Delayed union and non-union are rare. Children have greater remodeling potential, however this property also creates the possibility of overgrowth following a long bone (femur/tibia) fracture. This may lead to leg length discrepancy.
Growth plates may be injured resulting in angular growth deformity or limb shortening.
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Case: A basketball injury
Clinical photograph
X-ray
Case: A basketball injury
A 13-year old boy inverts his right foot during a basketball game. He has difficulty continuing to play and limps off the court with assistance. Examination reveals tenderness over the lateral malleolus and swelling and bruising of the anterolateral ankle. There is no tenderness in the foot. Review the clinical photograph and xrays of this patient.
Clinical photograph
This photograph was taken five days after the injury.
X-ray
AP x-ray of the affected ankle.
Describe what you see on the xray.
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The xray demonstrates soft tissue swelling over the lateral malleolus.
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In a child, which is more likely to be disrupted: the growth plate or an adjacent ligament? Explain why?
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Sprains are unusual in children. The physis (growth plate) will usually fracture before nearby ligaments tear. The ankle and the wrist are common sites of Salter I physeal fractures. This is a clinical diagnosis based upon the presence of an open growth plate, a history of injury and tenderness of the physis. Xrays often show little other than soft tissue swelling (if there is residual displacement at the growth plate, this would be visible on xray). In children, the growth plate functions as the "weak link" in the chain when force is applied.
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AP xray young child's wrist with physes marked
Growth plates (orange arrows pointing towards; also known as "physes") are found at the end of long bones in growing children. A layered pattern of cartilage (on the epiphyseal side) is gradually transformed into new bone exiting at the metaphyseal side of the physis.
Growth plate
Injury may disturb this process and create abnormalities of growth. The consequences of this depend on the degree of injury (all or part of the growth plate), the location (medial, central, lateral) and the growth potential of the child (defined by radiographic means as a "skeletal age"). Salter and Harris have classified these injuries.
The Salter-Harris classification of growth plate injuries.
The most common physeal fracture is a Salter II injury (below) with a triangular metaphyseal fragment and no involvement of the epiphysis. Lower grade Salter-Harris fractures (I, II) rarely result in growth disturbance while higher grade injuries (III, IV, V) frequently do.
This 10-year old boy twists his ankle during soccer practice. He is unable to weightbear and has an obviously swollen ankle. He visits the mall "walk-in" clinic the next day where an xray is taken.
Describe two complications that you are concerned about specific to this fracture type. How can they be avoided?
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This is a Salter III fracture that involves the articular surface, the epiphysis and the growth plate (physis). The two main concerns are articular irregularity which may lead to post-traumatic osteoarthritis and premature fusion of the growth plate at the fracture site which will lead to abnormal growth. If growth is halted on the medial ankle physis but the lateral physis functions normally then a varus deformity will result. The best treatment of this is open reduction and internal fixation to achieve anatomic fracture reduction and hold this during the period of healing. While this will not guarantee normal resumption of growth, it is the best treatment available. Salter III, IV and V fractures have a significant incidence of growth disturbance as they involve the active cartilagenous portion of the physis.
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In addition to anatomic differences, pediatric bone exhibits biomechanical differences as compared to the mature skeleton. Children's bone has increased porosity and a lower elastic modulus than that of adults. These properties are responsible for unique fracture patterns seen in childhood.
Buckle fracture
Greenstick fracture
Plastic deformation
Buckle fracture
This uniquely pediatric fracture pattern usually happens in the metaphyseal region of bone following a compressive force.
This three year old girl fell on her outstretched left arm while playing at daycare. Caregivers noted that she cried immediately and was reluctant to use the hand and arm normally for the rest of the day. This xray was done 24 hours later when her symptoms failed to resolve.
Can you identify the radiologic abnormality? Would you expect this fracture to be intrinsically stable or unstable?
Greenstick fracture
The greenstick fracture pattern is similar to the pattern of structural failure seen when bending an immature tree branch.
This four year old boy fell off his bicycle while learning how to ride independently. He cried immediately and was brought to the hospital for assessment. The triage nurse noted an obvious deformity at the wrist. This xray was taken at the Emergency Room one hour after the injury.
The cortex on the tension aspect of the applied force breaks while the cortex on the compression side bends or is plastically deformed. What problems might this create during treatment?
Plastic deformation
In plastic deformation no fracture is visible but the anatomic shape of the bone has been altered due to microscopic failure and "memory" of the bone. This is similar to bending a wire coat hanger. Plastic deformation often requires osteotomy (i.e. surgical cut of bone) to correct.
Angulated fracture of forearm with distal ulnar plastic deformation. The ulna is usually completely straight in AP and lateral xray views.
The radial fracture has been reduced and plated but the ulnar plastic deformation remains. Pronation/supination is restricted because of an abnormal curve in the distal ulna.
Osteotomy of the ulna has corrected the plastic deformation. Normal range of motion of the forearm is restored.
Initial assessment
Initially, the whole patient must be assessed to identify any life-threatening injury that would take precedence over a musculoskeletal injury "A,B,C"). Once assessed and stabilized (if necessary), assessment should focus on the injury to determine whether there are any complicating factors that would influence treatment choices. These include:
Skin integrity/open injury
Assessment of nerves
Assessment of blood vessels
Intra-articular fracture extension
Associated joint subluxation or dislocation
Reduction
Pediatric fractures, if undisplaced or minimally displaced, may require no reduction. Children can remodel fractures if the displacement is angular (not rotational) and in the plane of motion of the adjacent joint. A rule of thumb is that children can remodel 5 degrees for every year of growth remaining. Generally, girls grow until age 14 and boys until age 16. It is therefore reasonable to expect some pediatric fractures to remodel, reducing the need for "perfect" reduction. One notable exception is intra-articular fractures that need to be anatomically reduced to prevent (or reduce the chance of) post-traumatic arthritis.
Immobilization
Because of the thick periosteum and the intrinsic biomechanical properties of immature bone, pediatric fractures are often relatively stable and are generally quick to heal. Children's fractures are frequently immobilized using casts or splints. Traction was historically the treatment of choice for children's femoral fractures. However, over the past decade, it has fallen out of favour and is used less frequently than in the past.
Fractures requiring open reduction may be stabilized with percutaneous pinning, external or internal fixation with plates/screws. It is important to spare the growth plate when fixing a child's fracture; this consideration influences the choice of internal fixation. Standard long bone (femur, tibia, humerus) intramedullary rods are not used in children because of potential complications including avascular necrosis of the hip. Flexible intramedullary nails that can be inserted without crossing the physis are now used for long bone fractures in older children who require internal fixation.
Rehabilitation
Children are often described as their own "best physiotherapist" and therefore formal physiotherapy is less frequently prescribed than in adults. Nevertheless, especially in situations of return to sports and other activities, it in important to ensure adequate flexibility and strength prior to resuming full activities in order to reduce the chance of future injury.
General
Most of the complications associated with fractures/fracture treatment described in the Adult section may also develop in children. Because of the thick periosteum found in children, non-union is rarely described and is most likely in open fractures secondary to high-energy trauma. In particular, supracondylar humeral fractures are associated with a significant potential for serious complications including:
Vascular injury
Peripheral nerve injury
Compartment syndrome
Complications unique to childhood
Children may develop disturbances of growth after injury by one of two mechanisms:
Damage to all or part of the physis (growth plate) leading to limb shortening or angular deformity. This complication is more serious in young children with a significant amount of growth remaining and in large, rapidly growing physis such as the distal femur.
Overgrowth of a long bone. This occurs after fracture of the femur or tibia. Stimulation of the periosteum may, in addition to healing the fracture, cause lengthening of the limb. This is only likely between the ages of (approximately) 2 and 10 years as in the first two years of life and during adolescence, growth is already maximum. This complication is diagnosed within the first 24 months after healing of a long bone fracture and may require surgical intervention to correct any significant (> 2 cm) discrepancy.
A 6-year old girl is brought to hospital following a fall down 10 stairs. She has an obviously deformed right elbow and is complaining of severe pain. Her skin is intact but there is a sharp spike of bone palpable medially. Her hand is pink and warm and her radial pulse is palpable. She denies any numbness in her hand. She is able to flex her thumb IP joint, and extend her thumb MCP but has difficulty abducting her index finger. What immediate/early complications are you concerned about in this patient?
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This child has an extremely displaced supracondylar humeral fracture. Although her skin is intact, she is at risk to "secondarily" open the fracture if the subcutaneous spike of bone breaches the skin. In addition, she cannot abduct her index finger which suggests ulnar nerve dysfunction (despite the apparently normal sensory exam). The ulnar nerve is likely to have been stretched by the extreme fracture displacement. Supracondylar fractures are notorious for being associated with injuries to adjacent nerves (median, ulnar, radial) and vessels (the brachial artery may be transected, torn or compressed or may be secondarily affected by vasospasm). Compartment syndrome is a dreaded complication of supracondylar fracture, often associated with being casted in extreme flexion.
Intraoperative fluoroscopic image taken after closed reduction and pinning of fracture.
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Complete this matching exercise to assess your understanding of basic concepts.
A 2-year old child sustains the fracture pictured above while at gymnastics class. What would you recommend to correct the deformity that the child has sustained?
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Closed reduction and application of a hip spica cast (including chest, abdomen, hips and knee on the affected side; cast ends above knee on unaffected side) is the most common treatment for this injury in a child this age. While it is possible to fully reduce the fracture with sedation or general anesthesia, the fracture may "slip" within the first few weeks as swelling resolves. Fortunately, young children have excellent remodelling potential. Illustrated below are xrays taken of this child three and twelve months after the original injury and cast treatment. Note the remodelling of the femoral shaft over this time period.
3 months after injury
12 months after injury
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You have now completed the Pediatric Fractures module.
