Definition & Overview
External fixation systems are devices made of metal rods, wires, and pins designed to provide stability to fractured leg bones. There are several types, but the most common are uniplane and multiplane systems.
The human body has an amazing ability to heal itself, especially with regards to fractured bones. In fact, all that is needed is to return a displaced bone into its original position, stabilise it, and wait for the bone to heal itself.
Uniplane and multiplane external fixation systems play an important role in providing stability to the area while the bones heal. Such systems ensure that the displaced sections of bone are kept in place at all times.
The concept is simple, yet effective. Metal pins and wires are attached to certain areas of the bone away from the actual fracture. The other ends of pins are then attached to a metal rod that prevents the bones from moving in any direction. Once the fracture has sufficiently healed, the pins and rods can be removed.
Even though the pins are attached to the bone and protrude from the skin, surgeons ensure that there is a minimal amount of blood loss or tissue damage during the procedure and all throughout the healing process.
However, the procedure does have its disadvantages; it can result in significantly reduced mobility, and there’s a significant risk of infection while the pins are attached. Also, although they are effective in many types of bone fractures, they may not be the best choice for certain fractures as they may fail to provide adequate stability.
External fixators are usually used for tibia (shin bone) and distal radius fractures. The distal radius is one of the ten bones that make up the wrists and the most likely to be fractured in a wrist injury. The systems are not normally used for fractures of the femur (thighbone), humerus (bone from elbow to shoulder), and the forearms.
Who Should Undergo & Expected Results
As mentioned earlier, external fixation systems are only used to stabilise fractures on certain types of bones, such as the tibia and distal radius. Patients with the following types of injuries are good candidates for the procedure:
- Patients with open fractures (injury that damages the bone, skin, and other tissues leaving the bone exposed)
- Patients with closed fractures (injury that damages the bone but not the skin and other tissues)
- Patients with severe fractures that include the joints
- Patients that need to undergo leg lengthening procedures
The bone healing process can take several months to over a year depending on the type and extent of fracture. The patient’s age can also be a factor. It’s a known fact that children’s bones heal faster than adults.
It is also important to understand the healing process. After the fracture has occurred, blood will clot almost instantly at the exact location. At the same time, the immune system begins to remove any damaged cells from the area.
After a few weeks, the blood clot will begin to form into a substance called callus. The callus will in time form new bone, which is why it is imperative that fractured bones are returned to their original position shortly after the fracture occurs.
The callus is soft and unstable before it forms into bone. During this time, the fractured bones must be stable, which is why external fixation systems are affixed to the bones.
Once the callus has formed into a new bone, the fixation systems can be removed as the fracture would have had completely healed.
How Does the Procedure Work?
Prior to attaching a uniplane or multiplane external fixation system, doctors will take an image of the fractured bone using an x-ray. The doctors will then return the bones to their original positions, which may be done with or without an anaesthetic.
The doctors will then study the images and determine the areas where the pins of the fixator can be attached. The patient will be given a general anaesthetic prior to the procedure.
The surgeon will then use a drill to open a hole in the bone where the pins can be screwed into. On the other end of the pins, the rod will be attached and secured. The number of pins and rods used in the procedure will depend on the fracture. Multiple fractures may require several pins and rods, also referred to as multiplane external fixators.
The external rods are kept as close to the skin as possible, but should also allow access to open wounds for treatment. Moreover, the distance of rods from the skin must allow for any swelling that may occur in the area. If needed, the rods may be adjusted should more or less clearance be required.
Possible Risks and Complications
Even though external fixation systems are highly effective, there are still risks involved and a possibility that a complication may develop. One of the most common problems with this type of fixation system is that it may not provide sufficient stability to the bones.
There is also a risk of infections developing at the area where the pins are located. Such infections are referred to as pin tract infections. As such, the area needs to be monitored on a regular basis to look for signs of infection so it can be promptly treated.
Eben A. Carroll MD, L. Andrew Coleman MD; “External Fixation and Temporary Stabilization of Femoral and Tibial Trauma”; http://www.wheelessonline.com/userfiles/20-1-13.pdf
External Fixation article on Wikipedia; https://en.wikipedia.org/wiki/Externalfixation Bone healing article on Wikipedia; https://en.wikipedia.org/wiki/Bonehealing