Pediatric Forearm Injuries
About 40 percent of all pediatric fractures are of the forearm, which includes the radius and ulna. More than 80 percent happen to kids over the age of five years. Bone is weakened during these ages because there is a mismatch between bone growth and mineralization of bone. Supracondylar fractures are often associated with these injuries. Most occur in the distal metaphysis of the radius or ulna.
Mechanisms of injury include a fall on the outstretched hand. The degree of rotation of the forearm determines the direction of the angulation of the fracture. Direct injuries involve a direct blow to the radius or ulna.
Clinical Evaluation or Radius and Ulna Fractures
The patient often has an inability to use the forearm with pain, swelling, and tenderness of the affected area. Neurovascular injury can happen, particularly carpal tunnel syndrome. Because there can be other injuries, the hand, wrist and elbow must be evaluated to make sure there are no other fractures or dislocations. Compartment syndrome can happen if there is massive swelling of the forearm. If compartment syndrome is present, the child needs a fasciotomy. The skin integrity is important because of the possibility that the fracture might be open.
X-ray of the front and sides of the forearm, wrist and elbow should be taken if there is a suspected forearm injury,
In fractures of the radius and ulnar shaft, there can be compression fractures (torus or buckle fractures), displacement, angulation, or greenstick fractures.
Treatment of radius and ulna fractures
There should be correction of gross deformities so that soft tissue injuries using traction and counter-traction on the forearm. Light or heavy sedation (or even general anesthesia) should be used to achieve relocation of the fracture fragments, depending on the patient’s age and degree of dislocation. A well molded forearm cast is all that is necessary after closed reduction if the reduction is successful. If the fracture is open or if there is massive swelling, a cast should not be used until the swelling goes down or the open fracture healed.
The level of the fracture determines whether or not the forearm is supinated, neutral or pronated in the cast. The patient should be placed in the cast for 4-8 weeks or until bony union is established. Children tolerate more angulation and Bayonet deformities when compared to adults so there can be greater degrees of these types of deformities when reducing the fracture. Remodeling will usually occur, especially in very young children. Rotational deformities are less well tolerated.
Greenstick fractures are treated with a long arm cast that is well molded. The fracture should not be completed because there could be an increased risk of deformity of the fracture.
Surgical treatment should be done if the fracture is unstable or will not reduce externally. A floating elbow or open fracture should be treated surgically, as should a fracture associated with compartment syndrome. If the fracture breaks again with displacement, it should be treated surgically. If there is a segmental fracture or if the child has significant angulation and is older than 10 years of age, surgery should be performed.
Surgery involves intramedullary rods or wires to reduce the radius first and the ulna second. After this, a volar splint is applied for 4 weeks. The hardware may be left in place or removed after 6-9 months. Plate fixation is also a possible surgical intervention, especially if there is a comminuted or segmental fracture. Plates help with rotational deformities or in those who are skeletally mature. If there is a floating elbow, it means a supracondylar fracture has occurred along with the radius and ulna fracture.
Complications of forearm shaft fractures include refracture, malunion, synostosis, compartment syndrome, and nerve injury.
These involve a fracture to the proximal ulna with dislocation of the radial head. It makes up only about 0.4 percent of children’s forearm fractures. The ulna fracture is usually at the juncture of the proximal and middle third of the ulna.
Distal Radial Fractures
They often involve the growth plate of the distal radius with various Salter-Harris type fractures. These fractures can be complicated by carpal tunnel syndrome, ulnar styloid nonunion, and growth plate arrest.
Torus fractures are very stable because they are compression fractures. If the fracture is bicortical, it is treated with a long arm cast. Greenstick fractures should be treated with completion of the fracture with the arm in supination to reduce the pull of the brachioradialis muscle on the fracture. A long arm cast is recommended.Complications include malunion, nonunion, refracture (if returning to activity too soon), growth disturbance and neurovascular injuries.