Circular External Fixation
Raymond Liu, M.D.
This article provides an overview of circular external fixation. In essence, a circular external fixator offers excellent stability in all planes while allowing for gradual and controlled movements in a bone or joint. This allows treatment of complex orthopaedic conditions where a more immediate treatment is not as safe, or not possible. At times circular external fixation is safer because the slow correction avoids too much stretching at once of the blood vessels, nerves and skin. Circular external fixation can achieve greater corrections than acute osteotomies because the bone or joint is moved slowly, allowing the bone, joint and surrounding tissues time to adapt to the movement.
Circular external fixation generally involves the placement of two or more rings around the body part. Each ring is connected to the bone by wires or thicker pins. There are connections between the rings which stabilize the bone or joint in between and allow for precise movement to the bone or joint.
Circular external fixation can be used throughout the skeleton. It is more commonly used in the tibia (shin bone) and the foot.
When Is Circular External Fixation Recommend?
Circular external fixation is often used in circumstances when a bone or joint is severely deformed, when a bone is infected, in situations of non-healing fractures, or when the soft tissues around the bone or joint have been severely injured. Diagnoses include complex fractures, limb deformity, bone infection, bone loss, and contractures (situations where a joint does not have normal motion).
Preparing for Surgery
Circular external fixation is a large undertaking. In most other orthopaedic surgeries all of the changes are achieved the day of surgery, and recovery immediately starts. With circular external fixation, changes are made by the patient for a period of time following surgery, during which the position of the bone or joint is gradually improved. During this process, the muscles, tendons, ligaments, nerves, and skin are all gradually stretched, and this needs to be carefully monitored by your surgical team. For preparation it is important to have people who can help you at home during this process, which often lasts for months. It is also important to realize that you will have multiple clinical visits with the surgical team, as well as generally many visits with physical therapists.
Circular external fixation surgery times vary quite a bit, as there are a large variety of procedures that can be done. Generally patients are admitted to the hospital after surgery. During surgery, any necessary corresponding surgeries are performed, and circular external fixator rings are attached to the bone in at least two different sites. Some lower extremity circular external fixators are adapted for walking, while others are not. After the operation your surgeon will provide instructions on how to move the external fixator to correct your condition.
Circular external fixators are very complex devices, and usually used in difficult conditions including in patients who have multiple failed surgeries. So, complications often do occur. Most of these complications are mild, such as pin tract infections where the wires or pins enter the skin. Pin tract infections most commonly involve the soft tissues and usually can be treated with pin care and antibiotics. Extension of the infection into the bone is less common, but may need to be treated surgically and possibly with pin removal. Mechanical issues can arise with the circular external fixator, which may require modification in the clinic or with surgery. Problems can occur if the muscles, nerves, or other soft tissues are stretched too much, and frequent visits to the surgical team and to physical therapy are important to prevent and treat these issues. Severe muscle tightness or nerve issues may need surgical intervention. If a bone is separated and gradually corrected, it can heal too fast or too slow, possibly also requiring additional surgery.
The external fixator is first gradually manipulated to correct your bone or joint problem. After the correct position is achieved, the frame is kept in place to allow the bone to harden or the joint to adapt to its new position, which often takes months. Your surgeon will let you know when the frame is appropriate for removal. This generally occurs with an additional surgery which is commonly done as an outpatient procedure where you go home the same day. You might be placed into a cast or brace to protect your limb after frame removal. Physical therapy will continue to be an important part of the rehabilitative process, although there might be a rest period after frame removal to allow the bone to heal.