Pediatric Wrist and Hand Fractures
Carpal injuries are rare in children. They may be under-diagnosed because of the difficulties in getting a good x-ray of the carpal bones in kids. The most common injury in this area is a fracture of the adjacent physis in the distal radius. The bones of the carpus begin to ossify by the age of six months but isn’t complete until the age of 8 years. The small carpal bones are protected by cartilaginous shells until they begin to ossify. They ossify always in the same order for a total of 8 bones.
The most common mechanism of injury is a direct trauma to the area of the wrist. Falls on the outstretched hand can also injure the carpus but it is usually a high energy trauma, such as falling from a great height or falling from a bicycle.
Children usually present with tenderness over the site of the trauma. The median, radial, and ulnar nerves need to be evaluated and the child must be able to move and feel all fingers. X-rays of the affected area and a comparison view of the uninjured side can often help diagnose a fracture or dislocation. The most commonly fractured bone is the scaphoid bone. It is rarely injured in the first decade of life. Direct trauma is the most likely cause of a scaphoid bone fracture in kids. If the fracture is suspected but not seen on x-ray, a technetium bone scan or an ultrasound of the area may be helpful. Snuffbox tenderness is the biggest clinical sign of a scaphoid bone fracture.
The treatment of a scaphoid bone fracture is to put the patient in a thumb spica splint or cast if there is minimal swelling. A long arm cast should be used for initial immobilization. This treatment should continue for 2 weeks before re-evaluation is undertaken. If the fracture isn’t displaced, a long arm cast can be used with the wrist neutral for about 6-8 weeks. If the fracture is displace, it can be reduced externally with pinning of the bony segments. Adolescents with displaced fractures may need surgery.
Complications of a scaphoid fracture is a delay in union, nonunion of the fracture or malunion. Osteonecrosis can occur but is rare. Missed diagnoses are common and can be overcome by immobilizing a suspected fracture for 2 weeks and then reassessing the wrist.
Hand injuries can be seen mostly in toddlers and adolescents. It is more common in boys involved in sports. Most fractures of the hand in kids involve the metacarpal phalangeal joint area. Hand fractures overall are common, accounting for a fourth of all fractures in children.
The periosteum of the bone is very strong in the pediatric hand bones so that fractures that seem unstable are actually less so. Hand injuries can happen because of torque on the hand/fingers, angulation forces, compression of bone, and direct trauma. In some cases, shear forces can cause fractures of the hand in the epiphyseal plate or the physeal area.
It is difficult to evaluate kids with hand fractures because they often do not cooperate with an exam. Instead, observing the child can tell a lot about what is going on. The hand needs to be evaluated for open injuries that could lead to infection. The hand should be evaluated for neurovascular injuries by putting the hand in warm, sterile water for five minutes. If the hand wrinkles, there is no nerve injury.
X-rays of the front and sides of the hand can see the fracture. Sometimes oblique views are necessary. Stressing the hand and x-raying it can help show some nondisplaced fractures. Remember that the cartilage can be injured and this will not show up on x-ray.
In treating a hand injury, any puncture wound should be suspected as being a tooth injury. Antibiotics are necessary in this situation. Most hand fractures are treated with closed reduction using conscious sedation for comfort. Older kids can be reduced using finger traps that suspend the hand and reduce the fracture. Immobilization of a child’s hand injury can be done with a splint, including a metal splint. Most hand fractures heal within 4 weeks. If the hand fracture is unstable, percutaneous wires may need to be used to hold the fracture ends together.
The growth plates of the fingers are located at the proximal end of the bones. The periosteum tends to be very strong so that they resist becoming displaced. The most common phalanx to be fractured in kids is the proximal phalanx. If more than 25 percent of the fracture involves the joint, open reduction and internal fixation is necessary.
Distal phalanx fractures are often associated with soft tissue injuries and nail bed injuries. If the nail bed has a hematoma underneath the nail, it should be evacuated using a hot cautery device or hot paperclip. Complications of distal phalanx fractures include failure of the nail to grow properly. There can be an extensor lag of up to ten degrees, even when the fracture is treated properly. Other complications include malunion, nonunion, infection, osteomyelitis, and joint contracture.