Review of Syndesmotic Injuries of the AnkleMost people are familiar with the typical ankle injury that occurs just below the ankle bones. But there are other types of ankle injuries. One of those is the syndesmosis ankle sprain. The syndesmosis is a specific location in the upper ankle where the tibia and fibula (bones of the lower leg) meet.
In this article, sports orthopedic surgeons review the anatomy and biomechanics of the syndesmosis injury. They also present the mechanism of injury, method of diagnosis, and principles of treatment. Let's start with the basics of who, what, when, where, and how. Who's affected? Athletes and soldiers have the highest incidence of syndesmosis injuries. Football players, skiers, and hockey or basketball players are at increased risk of this injury.
What happens and how does it happen? The foot is dorsiflexed (toes pulled up toward the face) and pronated (forced down into a flatfoot position). The force is enough to tear the ligaments between the tibia and fibula. There are four syndesmotic ligaments.
At first, the ligaments are stretched. But when the force is enough to rupture the soft tissues, then the talus (major bone in the ankle) shifts its position. It externally rotates and pushes against the fibula. When that happens, the deltoid ligament of the ankle is also injured. In a chain of events, soft tissues and bones are damaged, shifted, and eventually ruptured. If the injury has a force strong enough, even the bone (fibula) can get fractured.
The rupture of one syndesmotic ligament usually isn't enough to reduce ankle stability. Once the deep deltoid ligament is damaged, then the ankle becomes unstable. If that happens, the patient is a candidate for surgery. Nonoperative management is not enough.
How does the surgeon evaluate and diagnose the problem? Of course, the history (what happened, how it happened) raises the suspicion of a syndesmosis injury. A physical exam is next. The surgeon palpates (feels) along the length of the bones for swelling and/or tenderness. Any signs of bruising are noted.
Special tests are performed that are designed just to look for a syndesmosis injury. These include the Cotton test, the Amendola stabilization test, the squeeze test, and the fibula translation (drawer) test. The examiner chooses the most appropriate test(s) for each patient. A separate test called the external rotation test has the best correlation with syndesmotic sprains. When this test is positive, the athlete can expect a longer recovery time before returning to a preinjury level of participation.
Imaging studies with X-rays, CT scans, and/or MRIs may be ordered. If a syndesmotic injury is suspected, the surgeon will order full-length films of the lower leg along with the standard ankle series. X-rays will show fractures and any change in the normal alignment of the tibia and fibula. Sometimes stress radiographs are taken. For the most sensitive and specific tests, MRIs are needed.
Once the injury has been identified and evaluated, the surgeon uses the information to classify it as a grade one, two, or three injury. The difference between the grades is based on amount of edema, tenderness, and ability to put weight on the foot. Distance between the two bones (as seen on imaging studies) is also factored into the classification.
The final step is to plan a course of treatment. There are two basic choices: conservative (nonoperative) care and surgery. There haven't been enough studies done to show what's the best way to approach conservative care. Right now, nonoperative treatment is broken down into three parts or phases.
Phase one is the acute phase. When there is swelling, the ankle joint must be protected until the inflammation is controlled. Moderately painful injuries are aided by an ankle brace or taping to provide compression and stability along with ice, rest, and elevation. Severe pain may require immobilization in a cast or splint. Physical therapy to restore normal joint motion and neuromuscular control may be needed.
Therapy continues during phase two, the subacute phase with strength and functional tasks. The program is progressed until the patient is no longer using assistive devices (splints, braces, crutches). When the athlete is ready for more advanced training, then phase three begins. The focus will be on returning the athlete to active sports participation at the preinjury level whenever possible.
There's no set amount of time before players return to sports. This varies according to the severity of the injury. Studies report anywhere from three and a half weeks up to two months before rehab is complete. In some cases, conservative care isn't even possible. Surgery to repair the damage and restore ankle stability is required. With surgery, recovery is delayed by three to four months.
Various types of surgery can be used to fix fractures, tighten the syndesmosis, and realign the ankle. Screws, sutures, suture buttons, and EndoButton suture techniques are surgical techniques used to stabilize the ankle syndesmosis. Research efforts are ongoing to find a way to return athletes to competitive play as early as six weeks after surgery.
Michael J. DeFranco, MD, et al. High Ankle Sprains Require a High Index of Suspicion. In The Journal of Musculoskeletal Medicine. December 2008. Vol. 25. No. 12. Pp. 564-569.
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