Syndesmotic ligament injuries, or more commonly known as high ankle sprains, are very common in the United States and can lead to chronic pain and instability if it is not recognized and treated appropriately.
Anatomy
The ankle syndesmosis is a group of ligaments that help to hold the tibia and fibula together just above the level of the ankle joint. This ligamentous complex is crucial in stabilizing the ankle joint while still allowing some motion to allow for rotation in the leg during weightbearing activities.
Mechanism of injury
It is estimated that 10% of all ankle sprains involve injury to the syndesmotic ligament. There are several mechanisms of injury to the syndesmotic ligamnet. Isolated syndesmotic ligament injuries often will occur when there is a forced upward motion of the ankle against the leg, causing separation of the tibia and fibula, and disruption of the syndesmotic ligament. Syndesmotic ligmanet injuries that often accompany an ankle fracture are usually injured when there is a forceful rotation of the ankle bone (talus) relative to the leg bone (tibia). Lastly, direct impact injuries during a fall, motor vehicle accident, or other injury may result in a high ankle sprain.
Diagnosis
Diagnosing syndesmotic injuries are done through clinical and radiological exams. Clinically, patients with a syndesmotic ligament injury will experience pain along the ligament and with stress of the ligament through a rotational force or by squeezing the leg bones (tibia and fibula) together. Although x-rays do not show ligaments, the alignment of the ankle joint, as well as associated fracture patterns of the ankle can give signs that a syndesmotic ligament injury has occurred. In cases where the clinical and x-ray exams are inconclusive, an MRI can be performed on the ankle to visualize the ligament.
Treatment
If the ankle joint is well aligned and there is no associated fracture, cast or boot immobilization for 6-8 weeks is recommended for the ligament to heal.
If the ankle joint is not well aligned, and/or there is an associated displaced fracture, surgery is needed to realign the bones and/or ligaments. The goal of surgical correction is to realign the ankle joint. After reduction of the ankle back into its anatomical alignment, there are two methods that are frequently used to help stabilize the ligament: Screw fixation and tightrope fixation
Screw fixation
Screws have been historically used to help stabilize the syndesmotic ligament after a injury. They are placed above the ankle joint, crossing the syndesmotic ligament. They are positional screws to help hold the tibia and fibula in place as the ligaments heal. Patients are in a non-weightbearing cast for 2-3 months to allow the ligaments to heal in a stable position before the screws are removed.
Tightrope
A tightrope can also be placed across the syndesmotic ligament to help stabilize the joint. This technology is newer, but provides an effective alternative to using screws to hold the ligament stable as it heals. A tightrope is a strong suture that is held to the bone with 2 buttons. The buttons abut against the bone and the suture is pulled tight, holding the bones in position as the syndesmotic ligament heals. The advantage to the tightrope is that no additional surgery is required to remove the tightrope after the syndesmotic ligament heals.
Conclusion
High ankle sprains are common and can lead to significant instability and pain. It is important to have a specialist evaluate your ankle after an injury to allow for the best possible results.
For an appointment with a doctor at one of our nine Greater Los Angeles and Southern California locations please call (877) 989-9110 or visit us at www.footankleinstitute.com.
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