Common Fractures

Chapter 675 Common Fractures




Trauma is a leading cause of death and disability in children >1 yr of age. Several factors make fractures of the immature skeleton different from those involving the mature skeleton. The anatomy, biomechanics, and physiology of the pediatric skeletal system are different from those of adults. This results in different fracture patterns (Fig. 675-1), diagnostic challenges, and management techniques specific to children to preserve growth and function.



Epiphyseal lines, rarefaction, dense growth lines, congenital fractures, and pseudofractures appear on radiographs, which could confuse the interpretation of a fracture. Most fractures in children heal well with indifferent treatment; that has led the unwary to neglect the fact that other fractures terminate disastrously if handled with inexpertise. The differences in the pediatric skeletal system predispose children to injuries different from those of adults. The important differences are the presence of periosseous cartilage, physes, and a thicker, stronger, more osteogenic periosteum that produces new bone, called callus, more rapidly and in greater amounts. The pediatric bone has low density and more porosity. The low density is due to lower mineral content and the increased porosity is due to increased number of haversian canals and vascular channels. These differences result in a comparatively lower modulus of elasticity and lower bending strength. The bone in children can fail either in tension or in compression; the fracture lines do not propagate as in adults, and hence there is less chance of comminuted fractures.


Joint injuries, dislocation, and ligament disruptions are uncommon in children. Damage to a contiguous physis is more likely. Interdigitating mammillary bodies and the perichondrial ring enhance the strength of the physes. Biomechanically, the physes are not as strong as the ligaments or metaphyseal bone. The physis is most resistant to traction and least resistant to torsional forces. The periosteum is loosely attached to the shaft of bone and adheres densely to the physeal periphery. The periosteum is usually injured in all fractures, but it is less likely to have complete circumferential rupture, due to its loose attachment to the shaft. This intact hinge or sleeve of periosteum lessens the extent of fracture displacement and assists in reduction. The thick periosteum can also act as an impediment to closed reduction, particularly if the fracture has penetrated the periosteum, or in reduction of displaced growth plate.



675.1 Unique Characteristics of Pediatric Fractures




Fracture Remodeling


Remodeling is the 3rd and final phase in biology of fracture healing, preceded by the inflammatory and reparative phases. This occurs from a combination of appositional bone deposition on the concavity of deformity, resorption on the convexity, and asymmetric physeal growth. Thus, reduction accuracy is somewhat less important than it is in adults (Fig. 675-2). The 3 major factors that have a bearing on the potential for angular correction are skeletal age, distance to the joint, and orientation to the joint axis. The rotational deformity and angular deformity not in the axis of the joint motion are less likely to remodel. The amount of remaining growth provides the basis for remodeling; younger children have greater remodeling potential. Fractures adjacent to a physis undergo the greatest amount of remodeling, provided that the deformity is in the plane of the axis of motion for that joint. The fractures away from the elbow and closer to the knee joint have greater potential to remodel because this physis provides maximal growth to the bone. One can expect remodeling to occur over the next several months following injury throughout skeletal maturity. Skeletal maturity is reached in girls between 13 and 15 yr and in boys between 14 and 16 yr of age.








675.2 Pediatric Fracture Patterns




The different pediatric fracture patterns are the reflection of a child’s characteristic skeletal system. The majority of pediatric fractures can be managed by closed methods and heal well.







Epiphyseal Fractures


The injuries to the epiphysis involve the growth plate. There is always a potential for deformity to occur, and hence long-term observation is necessary. The distal radial physis is the most commonly injured physis. Salter and Harris (SH) classified epiphyseal injuries into 5 groups (Table 675-1 and Fig. 675-7). This classification helps to predict the outcome of the injury and offers guidelines in formulating treatment. SH type I and II fractures usually can be managed by closed reduction techniques and do not require perfect alignment, because they tend to remodel with growth. SH type II fractures of the distal femoral epiphysis need anatomic reduction. The SH type III and IV epiphyseal fractures involve the articular surface and require anatomic alignment to prevent any step off and realign the growth cells of the physis. SH type V fractures are usually not diagnosed initially. They manifest in the future with growth disturbance. Other injuries to the epiphysis are avulsion injuries of the tibial spine and muscle attachments to the pelvis. Osteochondral fractures are also defined as physeal injuries that do not involve the growth plate.


Table 675-1 SALTER-HARRIS CLASSIFICATION





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Jun 18, 2016 | Posted by in PEDIATRICS | Comments Off on Common Fractures

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SALTER-HARRIS TYPE