Radius and Ulna Shaft Fractures
The radius and ulna are the two long bones of the forearm that allow the hand and wrist to move as well as take part in elbow function. Fractures of the radius and ulna are more common in men than in women because they are more often to be in motor vehicle accidents or play sports that contribute to getting forearm fractures of the radius and ulna. Fractures of the forearm are more likely to be open fractures when compared to all other areas of the body with the exception of the tibia.
The radius and ulna help flex and extend the wrist and elbow. They are also responsible for pronation and supination of the forearm. Pronation is the act of twisting the forearm so that the palm side is down, while supination is the reverse—the palm side is up. There is a membrane called the “interosseous membrane” that connects the radius and ulna together along the shaft. If this band is disrupted, the forearm can become unstable by about 70 percent.
Mechanism of Injury
The fractures of the radius and ulna usually result from motorcycle injuries or motor vehicle accidents that are high impact types of injuries. Direct blows to the forearm can also cause these bones to be fractured, such as is seen in falls from a great height or a sports-related injury.
Evaluation of Radius and Ulna Fractures
These patients often arrive at the emergency department with a deformity of the forearm, extreme pain in the forearm, swelling and loss of ability to use the hand or forearm. Because these can result in a lot of swelling, compartment syndrome must be looked for. This involves swelling that is so severe that it compresses and damages the arteries and nerves that travel through that area. This means that a careful neurovascular assessment needs to be done on the forearm and hand to make sure that the nerves and arteries are working and not disrupted.
If the pain seems to be out of proportion to the injury and is not improved with splinting, compartment syndrome should be suspected and the surgeon needs to be notified about doing a possible fasciotomy in order to relieve the pressure in the forearm.
X-rays of the forearm, including the AP and lateral views can easily show the fractured areas in most cases. The elbow and wrist should also be x-rayed in order to make sure there are no other injuries or dislocations at these sites. Make sure the radial head is properly aligned with the capitellum in all x-ray views taken of the elbow.
Classification of Radial and Ulnar Fractures
These fractures are classified according to several descriptive ways. These are some ways to classify radius and ulna fractures:
- Location of the fracture
- Closed versus open fracture
- Comminuted, multifragmented or segmental fractures
- Displaced fractures
- Rotation of the bones
- Angulation of the bones
A long arm cast can be used to treat these types of fractures if they are not displaced or angulated. Unfortunately, this isn’t the case in most radius and ulna shaft fractures. If a cast is done, there should be frequent follow up to make sure that the bones aren’t becoming more displaced or that there is no further neurovascular compromise from the cast being too tight.
If there is any deformity, angulation or displacement, the radius and ulna need to be repaired surgically. Plates are often used to hold the fractured pieces together. The plates must be used in such a way as to keep the length of the forearm bones intact and rotational realignment must take place before a plate is placed. The radius isn’t straight normally so its natural bowing must be kept as it was before the injury so that pronation and supination aren’t affected.
The surgeon can cut across the back or the front of the forearm, depending on the location of the fracture and ease of access to the bones. Bone grafting might be necessary in order to fix areas where bone has been lost completely. Open fractures need both surgery and antibiotics to prevent infection in the bone. Sometimes more than one surgery is required if the fracture is open and bone grafting is necessary. Surgery can be delayed for up to six weeks following the injury.
Common complications include the following:
- Nonunion or Malunion of the bone. This can happen if infection sets into the bone but is uncommon.
- This can happen in about 3 percent of open reduction and internal fixation of the bones. External fixation might be required if the infection is severe and needs repetitive debridement.
- Neurovascular injury. This can happen with penetration injuries or accidentally in surgery. If there is a missed compartment syndrome. If compartment syndrome is suspected, an emergency fasciotomy needs to take place.
- Post traumatic radioulnar synostosis. This happens when there has been a severe crush injury that damages soft tissue. This complication can be avoided by using separate incisions for the radius and ulnar fracture repairs. The incidence of this occurring is about 3-9 percent but is higher if both bones are broken at the same level so that the bones cannot separate well from one another.
One type of ulna fracture includes a Monteggia fracture, in which the ulna is broken and the radial head is dislocated. There are several types of Monteggia fractures that are produced by various mechanisms.
Nightstick fractures of the ulna are produced by a direct blow onto the ulna. These patients have swelling of the affected area, pain, tenderness and abrasions over the ulnar area. X-rays can show this type of fracture using a lateral and AP view.
There can be isolated fractures of the radius, usually in the proximal two thirds of the shaft. If the distal third is involved, there is a much greater likelihood of having a distal radioulnar dislocation as part of the fracture. Fractures of the radius are likely to be deformed because of the weight of the hand on the fractured segment as well as the insertion of various muscles that pull the fracture out of alignment.
Nondisplaced radial fractures can be treated with a long arm cast but if there is any evidence that the normal bow-shape of the radius is lost, then surgery is required. Displaced fractures of the radius must be treated with open surgery. Usually plates are used to fix the fracture segments together.
If there is any neurovascular injury as part of a radial fracture, it is usually the result of a surgeon’s mistakenly damaging the vessel or nerve. Usually, the nerve recovers itself within three month.