Edited by Peter Stavrou, MD
Surgery to fix an ankle fracture is indicated for patients who suffer a displaced unstable ankle fracture involving either the bone on the inside of the ankle (the medial malleolus), the bone on the outside of the ankle (the lateral malleolus which is also known as the fibula), or both.
The ankle is not a joint that tolerates any displacement as this will lead to uneven loading of the ankle joint, and the subsequent development of ankle arthritis (loss of joint cartilage) in a short period of time. If an ankle fracture has lead to a displaced or unstable ankle joint, (Figure 1) then surgery is indicated for most patients surgery (some high risk patients may not be surgical candidates).
One injury that may occur in conjunction with an ankle fracture is a disruption of the syndesmosis. A syndesmostic injury is a disruption of the strong fibrous ligaments that hold the fibula and tibia together, near the ankle joint. If the syndesmosis is disrupted, then the ankle joint will be unstable and surgery is usually indicated.
Figure 1: Displaced fibular fracture with displaced ankle joint
Lateral Malleolus Fracture (Distal Fibula Fracture)
To fix a fracture on the outside of the ankle, (lateral malleolus fracture) an incision is made on the outside of the ankle, essentially along the line of the fibula (the prominent bone on the outside of the ankle). The soft-tissues (tendons, muscles, ligaments) are dissected down to the fracture site. The fracture itself is cleaned up (ex. clotted blood is removed) and the bones are put back together, hopefully in the exact position (anatomic alignment) that they were in prior to the fracture. Once positioned, there are a variety of ways to fix (stabilize) the bones. The most common method is putting a screw across the fracture site for compression. This is followed by a metal plate with a series of screws to hold the fibula in its position (Figure 2).
Figure 2: Lateral Malleolus (Distal Fibula) Fracture after surgery
Medial Malleolus Fracture
A fracture of the bone on the inside of the ankle (medial malleolus) is approached through an incision on the inside of the ankle. A vertical incision is made and the surgeon dissects down to the fracture site. The fracture is cleaned up, which includes removal of any clotted blood (hematoma) from around the fracture site. Once prepared, the fracture fragments are put back into position with the aim of positioning the bone fragments in the exact position that they were in prior to the fracture. Once positioned the fracture is usually secured with two screws.
This procedure involves surgical treatment of both a fractured medial malleolus and lateral malleolus. These two procedures are done separately (two different incisions) but are performed together under the same anesthetic. Like each individual procedure, the goal is to reduce the fractures into the position that they were in prior to the fracture and to ensure that the ankle joint itself is perfectly positioned (anatomically reduced) and stable.
This procedure is similar to that used to fix a bimalleolar ankle fracture, except it also involves a fragment in the back aspect (posterior) of the tibia. If the fragment represents less than 20% of the joint suface of the tibia (as viewed on the lateral xray from the side of the joint), then it is disregarded and treated like a bimalleolar fracture. However, if greater than 20%, the fragment needs to be repositioned. Reducing the fragment can be done in a similar process to a lateral malleolus fracture or by making an incision near the back, outside aspect of the ankle. Once reduced, it is usually fixed with a screw or two from the front to the back of the ankle.
When an ankle fracture occurs, it is not only the bones that are injured. All the surrounding structures ( tendons, ligaments, muscles, nerves, joint cartilage) also sustain injury, which can vary from minor to permanent. One of these structures, articular cartilage (the cartilage that lines the joint surfaces) can be damaged or scarring can occur within the joint. This can cause ongoing pain that sometimes requires further surgery, such as arthroscopy to look inside the joint.
Stabilizing a Syndesmotic Injury/Disruption
If the strong fibrous tissues holding the tibia and fibula together (syndesmosis) is injured (partially torn) or disrupted, (completely torn) it should be repaired. This injury can occur with a fracture of the fibula far away from the ankle joint or without any fracture at all. The surgeon will often assess the stability of the syndesmosis, either before or during surgery, by “stressing” the ankle under fluoroscopy (a portable x-ray) or performing weight bearing xrays (if this is possible) to see if the ankle “opens up” (does the talus shift out of position when stressed). The syndesmosis can sometimes be assessed during an ankle arthroscopy (looking inside the ankle joint with a small camera). If the syndesmosis is determined to be unstable, the syndesmosis is stablized so that it will heal in the desired (reduced) position. The syndesmosis is usually stablized by putting one or two screws across the fibula and into the tibia, in order to stabilize these bones and allow the syndesmosis to heal. After approximately 3-6 months, (once the syndesmosis has healed) the screws are removed. In some situations, the surgeon may choose to repair the syndesmosis directly with strong sutures.
0-6 weeks Post-Surgery
Patients undergoing this type of surgery will typically need about 6 weeks for the bone to heal. During this period, the patient is either in a cast boot or post-operative shoe and remains non-weight bearing or touch weight-bearing through the heel.
6-10 (or 12) weeks Post Surgery
At 6 weeks post-operatively, patient can begin to increase weight bearing as tolerated in a protective boot.
10 (or 12) weeks + Post-Surgery
Patients can begin transitioning into a shoe and continue to rehabilitate at this point.
Injury to the Superficial peroneal nerve or the Sural nerve can occur due to the placement of the incisions, specifically for a lateral malleolous fracture. Nerve injury can occur due to retraction, direct injury, or from scarring during the recovery process. If these nerves are injured or cut, the patient could end up with numbness or pain along the path of the nerve (onto the top or outside of the foot).
Due to the lack of movement after the surgery, calf muscles have a potential to atrophy. The calf muscles may take a while to strengthen, which may never reach their full potential prior to surgery.
The capsule surrounding the ankle joint may get stiff, which may decrease the range of motion around the ankle joint.
About 15-20% of patients experience pain associated with the screws and plates that are used to secure the bone fragments. These patients will need to undergo removal of the screws due to discomfort, once the bones have healed.
Post-Traumatic Ankle Arthritis
Having an ankle fracture will increase the chances of obtaining ankle arthritis. Ankle arthritis is about 10 times less common than hip or knee arthritis. Most patients who have an ankle fracture will not develop significant arthritis. However, the majority of the patients who develop ankle arthritis have had a significant ankle injury in the past.
Failure of Hardware with Syndesmosis
If the syndesmosis is fixed, there may be a potential for the screws to break at the syndesmosis if they are not taken out early enough. Although it may sound very troubling, the broken screws have no bearing on the patient’s symptoms. The potential complication is not considered significant; however, it may interfere with the resolution of an MRI.
Failure of Syndesmotic Fixation
Rarely, after removal of the syndesmotic fixation, an injury may recur if the ligaments have not healed adequately. This may show itself as ongoing pain in the region. Should this happen, it may require further surgery to the region.
Some patients may be at risk of venous thromboembolism (clotting) related to the surgery and post-operative immobilisation. Your surgeon may choose to commence anticoagulation (blood thinning medications) after undertaking a risk assessment of your situation. Those most at risk of venous thromboembolism are those who have had blood clots in the past.
Edited March 12, 2015