The ankle is made up of the tibia and fibula bones of the lower leg, and the tarsus bone of the foot. They are held together by ligaments, which provide strength and stability during movement.
The tibia and the fibula are held together by the syndesmosis joint, a special joint that allows very little motion between the bones, but provides strong stability to the ankle joint. Ligaments that connect the tibia and fibula include:
- Anterior inferior tibio-fibular ligament: present in front of the two bones
- Posterior inferior tibio-fibular ligament: present behind the two bones
- Transverse ligament: crosses over the back of the bones
- Interosseous ligament: present between the two bones
Any twisting or rotational injury, especially forceful upward and outward movements of the foot, can injure the syndesmosis ligaments causing stretching or tearing of the ligaments.
Syndesmosis injuries, also called high-ankle sprains, are commonly seen in high-level football players and snow skiers. It is a severe type of foot and ankle sprain causing pain, swelling and weakness. In some cases, the tibia and fibula may draw apart (diastasis) resulting in ankle instability. This type of injury often requires surgery to restore the stability and function of the ankle.
Syndesmosis surgery is indicated in cases of diastasis causing instability or when conservative treatment measures do not help relieve ankle pain and weakness. Conservative measures include pain and anti-inflammatory medications, rest, ice, compression, elevation and ankle bracing.
However, surgery may be contraindicated if certain medical conditions make surgery risky, or the ankle has a chronic wound or active infection present.
Surgery is performed under general anesthesia usually on an outpatient basis but may require an overnight stay.
- Your surgeon makes an incision over the ankle joint and removes any impeding structures such as scar tissue keeping the tibia and fibular apart.
- Your surgeon uses fluoroscopy (real-time X-ray imaging) to insert screws or implants to hold the two bones together. The screws are inserted through a small incision made on the side of the ankle, going from the fibula into the tibia.
- A second screw or plate is sometimes inserted for added stability.
- Large screw heads are selected for easy removal once the ligaments heal
- X-rays of both ankles are then taken to compare the tibia-fibula distance. A stress X-ray is also performed to check stability.
- Once your surgeon is satisfied with the results, the skin is sutured close and a splint or cast is applied.
The splint is kept on for a period of 2-4 weeks during which time you must not bear any weight on the leg. After this period, the foot is placed in a walking boot or crutches with minimal weight bearing and gentle ankle movements. Physical therapy is recommended for at least 3-4 months to improve strength and mobility. More strenuous exercises can be gradually introduced after a minimum of 12 weeks.
Risks and Complications
As with any surgery, syndesmosis surgery may include certain risks and complications such as bleeding, blood clots, infection, and damage to nerves and blood vessels. There is also the risk of hardware failure (screw breakage) and improper healing.