The ankle syndesmosis is made up of four ligaments that work together to stabilize the articulation of the tibia and fibula (the two bones in the lower leg between the knee and the ankle). The fibula is the smaller bone on the outside of the leg and the tibia is the larger bone often referred to as the “shin bone.”
Syndesmosis injuries often occur withother ankle injuries, including sprains andfractures.A syndesmosis injury is often called a “high ankle sprain.”
If a damaged syndesmosis is left untreated, the normal stability of the distal talofibular joint is disrupted, which can lead to chronic instability and, ultimately, degenerative arthritis.
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A syndesmosis injury is most commonly due to an external rotation mechanism of injury (i.e. when the foot twists outwards relative to the leg).Another common mechanism of injury is when the foot is planted and the leg is twisted inward, whether from an impact or forceful change of direction.
Symptoms
As mentioned, syndesmosis injuries often occur in conjunction with ankle injuries. Therefore, anyone with anankle sprainor fracture should also be evaluated for a possible injury to the syndesmosis.
Typical symptoms of a syndesmosis injury include:
X-rays should be obtained if an injury to the syndesmosis is suspected. Because normal X-rays may not show a syndesmosis injury, a special type of X-ray called a stress X-ray is often obtained.
During a stress X-ray, the examiner will apply a force to the ankle to determine if the integrity of the syndesmosis is intact, which demonstrates the stability or instability of the joint. If the stress X-ray is inconclusive, magnetic resonance imaging (MRI) is the gold standard for diagnosing syndesmosis injuries.
Types
The most common type of syndesmosis injury is called ahigh ankle sprain.A high ankle sprain simply refers to damage to the ligaments above the ankle joint—the syndesmotic ligaments. The four ligaments of the syndesmosis are:
Treatment of a high ankle sprain depends on the stability of the ankle.
If the syndesmosis is unstable (grade 2 or 3), treatment must ensure the syndesmosis can be held in a stable position while healing. This typically requires surgical reduction and internal fixation to stabilize the joint.
Syndesmosis injuries can also occur in association with ankle fractures.As with high ankle sprains, the critical information for determining treatment is if the ankle joint is unstable. When the syndesmosis is damaged in association with a fracture of the ankle, surgery is usually necessary to restore stability to the ankle joint. Surgery is often performed to repair the fracture or to stabilize the syndesmosis, and sometimes both.
Surgery
When the syndesmosis is repaired surgically, this is usually done with metal screws that pass through the fibula and into the tibia. These screws must be positioned once the syndesmosis has been placed in proper position and alignment. Either one or two screws may be used, depending on the type of injury and your surgeon’s preference.Often, your surgeon will recommend removing the screws after about 3-4 months.
If the screws are not removed, they will eventually loosen or break. While this may not present any issues, many patients don’t want a loose or broken screw in their leg, and would, therefore, have them removed before that time.
Summary
9 Sources
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