The syndesmotic ligament complex is a fibrous joint in the lower leg, connecting the tibia and fibula just above the ankle. These strong connective tissues maintain ankle stability and prevent excessive bone separation.
Anatomy and Function
The distal tibiofibular syndesmosis is a fibrous joint where the convex surface of the fibula meets the concave fibular notch of the tibia. This articulation is secured by four primary ligaments: the anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), the interosseous ligament (IOL), and the inferior transverse ligament (ITL). The interosseous ligament is a distal continuation of the interosseous membrane, which runs between the tibia and fibula. These ligaments collectively maintain the integrity of the ankle mortise, the socket formed by the tibia and fibula that cradles the talus bone of the foot. This stability is important during weight-bearing activities and movements that involve twisting or rotation of the foot.
High Ankle Sprains
An injury to the syndesmotic ligament complex is commonly known as a “high ankle sprain,” distinguishing it from typical ankle sprains affecting the ligaments on the outer side of the ankle. These injuries occur when the ligaments connecting the tibia and fibula are stretched or torn. The most common mechanisms of injury involve forceful external rotation of the foot or hyperdorsiflexion, where the foot is pushed excessively upwards. A high ankle sprain often presents with pain located higher up the leg, specifically above the ankle joint between the tibia and fibula. While swelling and bruising can occur, individuals often experience significant pain with weight-bearing activities, particularly when climbing stairs or pushing off the toes, as these movements place increased stress on the injured ligaments.
Diagnosis and Treatment
Diagnosis
Diagnosing a syndesmotic ligament injury involves a physical examination and imaging tests. During examination, a healthcare provider may perform the “squeeze test,” where the tibia and fibula are compressed together at the mid-calf level; pain suggests a high ankle sprain. Another common test is the external rotation test, where the foot is turned outwards while the leg is stabilized, eliciting pain if the syndesmosis is injured. X-rays are the initial imaging to rule out associated fractures and check for widening between the tibia and fibula, which indicates syndesmotic disruption. Magnetic Resonance Imaging (MRI) provides detailed views of soft tissue damage, including the ligaments and the extent of the injury. Computed Tomography (CT) scans offer accurate visualization of the bony relationship between the tibia and fibula.
Treatment
Treatment approaches vary based on the severity of the syndesmotic injury. For stable injuries (Grade 1, a sprain without instability), conservative management is recommended. This often includes rest, ice, compression, elevation (PRICE protocol), and immobilization in a boot or cast for 1 to 3 weeks, followed by a gradual return to activity. NSAIDs may be used to manage pain and swelling. Unstable injuries, which involve significant ligament disruption or separation of the tibia and fibula (Grade 2 with instability, or Grade 3 complete tears), often require surgical intervention. Surgery aims to restore proper alignment and stability. Common surgical techniques include syndesmotic screw fixation, where a screw is placed across the tibia and fibula, or suture-button fixation systems that use a suture construct to stabilize the joint.
Recovery and Rehabilitation
Recovery from a syndesmotic ligament injury can be a lengthy process, often taking longer than a typical ankle sprain, ranging from several weeks to many months. The timeline for return to full activity is variable and depends on the severity of the sprain and the chosen treatment method. Gradual progression through rehabilitation phases is important for proper healing and to prevent re-injury. Physical therapy is a core component of rehabilitation, focusing on reducing pain and swelling while protecting the joint through immobilization or limited weight-bearing. As pain subsides, rehabilitation progresses to restoring the ankle’s range of motion, improving muscle strength in the surrounding calf and leg muscles, and regaining proprioception, which is the body’s sense of joint position and movement. This helps individuals regain stability and function for daily activities and sports participation.