FRACTURE SEPARATION OF THE RADIUS IN CHILDREN

Abstract

Proximal Radius – Fractures of the proximal radius in children account for slightly more than 1% of all children’s fractures, represent 5 to 10% of all elbow fractures and accounts for 5% of all fractures involving the growth plate. The average age in the literature is 10 years (4 to 16 years) with no difference between boys and girls.

The anatomical aspects should be emphasized for the comprehension of this fracture: 1) the radial head of the child only starts to ossify at age 5 so it is very rare to have a fracture before this age since all the head is cartilaginous and therefore more resistant to trauma. At the same time it makes more difficult the diagnosis because of the absence of ossification of the epiphysis. 2) There is a valgus angulation of 12.5° between the radial head and the shaft of the radius in the AP plan and an anterior angulation of 3° on the lateral plane that should not be misinterpreted as fractures. 3) The radial head is intrarticular in a similar way like the femoral head and trauma to this region may lead to AVN as a result of damage to the vascular supply of the epiphysis. 4) The proximal radioulnar joint has a very intimate continuity contributing to exact congruence of the articular surfaces. The axis of rotation lies directly in the center of the radial neck. Any deviation of the epiphysis over the neck has a major reflect over the axis of rotation causing a “cam” effect when the radial head rotates with loss of pronosupination.

The mechanism of injury responsible for this injury result from a fall on the outstretched upper extremity in which the elbow is extended and a valgus force is applied to the elbow joint. In more rare cases it result from direct pressure to the radial head during dislocation of the elbow.

There are different classifications mostly based on the anatomical lesion or degree of deformity. Wilkins divides this fracture in two major groups: Group I (valgus fracture) subdivided in three types: type A – the Salter-Harris type I and II, type B – Salter-Harris type IV and type C – fractures involving only the proximal radial metaphysis and Group II (fractures associated with elbow dislocation) subdivided in two types: type D – reduction injuries and type E – dislocation injuries. O’Brien divides the common valgus injury in three types according to the degree of angulation between the radial head and the axis of the radius: Type I (0 to 30° angulation) Type II (between 30° and 60°) and Type III (more than 60°).

The clinical symptoms may vary according to the magnitude of the injury. The child will mostly complaint of pain and tenderness on the lateral side of the joint. In young children pain may first be referred to the wrist. The pain usually increases with pronosupination and extension of the elbow.

The diagnosis relies mostly on the x-ray view (AP and lateral) and the fracture will be easily visualized in either film. In the cases where the fracture line is superimposed over the ulna an oblique view will be necessary. In the young child, whereas the epiphysis is still not ossified, an ultrasound may be helpful differentiating the position of the radial head. An arthrogram may also be of benefit especially during the process of reduction to check the accuracy of the treatment.

The prognosis of this lesion depends on several factors. A poor result can be expected if the fracture is associated with other injuries such as elbow dislocation and ulna or medial epicondylar fractures. A residual tilt of the radial head, provided is not superior to 30°, is more tolerable than a translocation of the radial head superior to 4mm. Age is also an important factor since the older the child the less remodeling it will have. The treatment has also an important role in the prognosis of this injury since it is unanimous acceptable that an open reduction is associated with poor results.

Therefore the treatment of a young child with an isolated minimal displaced fracture-separation of the proximal radius (less than 30°) should be a simple long arm cast. In a more displaced fracture (more than 30° of tilt) a closed reduction should be performed under general anesthesia as suggested by Patterson. If the maneuver is not successful other attempts should be made with lateral pin compression applied directly to the radial head as suggested by Pesudo or an indirect reduction by an intramedullary kirschner wire as suggested by Metaizeau. Open reduction should be only reserved for dislocated Grade IV Salter-Harris type fractures, incarcerated radial head or in the presence of failure of closed treatment.

The incidence of complications especially if associated with a dislocation of the elbow or other fractures can be high. The most common are loss of motion, radial head overgrowth usually with no clinical significance, notching of the radial neck and premature physeal closure. Avascular necrosis of the radial head is most commonly associated with open reduction.

Distal Radius – It is the most common fracture separation in children and represent 46% of all fractures involving the growth plate. A fracture of the ulna is associated in 6 to 11% of the injuries. The average age is 12 years with a minimum of 7 and a maximum of 16 years. Although this high incidence it is very uncommon subsequent growth disturbance.

The usual mechanism of injury is similar to the proximal radius injury and result from a fall on the outstretched upper extremity with the wrist hyperextended.

This type of injury is classified by the Salter-Harris classification for physeal fractures and the most commons are the types I and II.

The clinical symptoms vary from mild tenderness over the fracture site to a noticeable deformity most often with the apex volar. Attention should be given to the possibility of vascular and neural injury associated, mostly from the time of the acute deformation, and the diagnosis is made by x-ray view (AP and lateral) with the fracture well visualized.

The prognosis is in general good since even in the presence of a markedly displaced fracture it can be expected a remarkably remodeling even in an older child.

Treatment in a nondisplaced fracture only requires a below elbow cast for 4 weeks. In a displaced fracture a closed reduction should be performed under hematoma block or general anesthesia (in a young child). The reduction is stable most of the times in a plaster with the wrist in slight flexion. The incidence of complications is very rare.