Injuries to the ankle syndesmosis, frequently termed "high ankle sprains", are complex injuries involving the ligaments that maintain the relationship between the distal tibia and fibula.
Epidemiology¶
Syndesmotic injuries are increasingly common, representing between 1% and 20% of all acute ankle injuries. In athletic populations, this prevalence can be higher, accounting for up to 25% of all ankle sprains.
High-Risk Sports:¶
These injuries are most prevalent in impact and collision sports, including soccer, rugby, American football, ice hockey, wrestling, skiing, and basketball.
Injury Burden:¶
Compared to lateral ankle ligament injuries, syndesmotic tears result in substantially longer time loss from sport, a higher likelihood of requiring surgical stabilisation, and more long-term functional sequelae. For example, NFL players lose an average of 11.7 practices for a high ankle sprain compared to 3.5 for a lateral sprain.
Demographics:¶
Injuries are most frequent in the second to third decades of life, particularly among those aged 18 to 34. While evidence regarding gender is conflicting, some studies suggest a higher incidence in males. Higher BMI has also been identified as a potential risk factor.
Knowledge Check
Syndesmotic injuries represent between 1% and 20% of all acute ankle injuries, but in athletic populations, this prevalence can be higher, accounting for up to 25% of all ankle sprains. These injuries are most prevalent in impact and collision sports.
Typical Presentation¶
The diagnosis of syndesmosis injury can be difficult, as presentation is often nonspecific and may be missed in the absence of a fracture.
Mechanism of Injury:¶
The most common cause is supraphysiologic external rotation of the foot while it is planted and in a dorsiflexed position. Less common mechanisms include abduction or eversion.
Knowledge Check
The most common mechanism of injury is supraphysiologic external rotation of the foot while it is planted and in a dorsiflexed position (e.g., an athlete's foot is planted and they are tackled from the side). Less common mechanisms include abduction or eversion.
Clinical Symptoms:¶
Patients typically report diffuse pain about the ankle, specifically felt anterolaterally and proximal to the joint line. Pain is often exacerbated by weight-bearing, pivoting, walking up hills, or performing a single-leg heel raise. Swelling and bruising may be less pronounced than in typical lateral sprains because the damaged tissue is extracapsular.
Physical Examination:¶
Tenderness is usually present over the anterior inferior tibiofibular ligament (AITFL) and may extend proximally up the leg ("tenderness length"). Several provocative tests are used:
◦ Squeeze Test: Compressing the mid-calf reproduces pain at the distal syndesmosis.
◦ External Rotation Stress Test: Applying external rotation force to the foot with the knee flexed reproduces pain.
◦ Cotton Test: Medial and lateral forces applied to the talus to detect increased mediolateral movement.
◦ Fibular Translation Test: Attempting to translate the fibula anteriorly and posteriorly on the tibia.
Diagnostic Tools:¶
Clinicians cannot rely on a single physical test; a combination is required. MRI is the gold standard, offering high sensitivity and specificity for acute tears. Radiographs are used to rule out fractures and check for diastasis (widening of the tibiofibular clear space).
Knowledge Check
The squeeze test involves compressing the mid-calf to reproduce pain at the distal syndesmosis. This test is one of several provocative tests used to assess syndesmotic injuries, though clinicians cannot rely on a single physical test and a combination is required.
Management¶
Management is dictated by the grade of injury and the presence of associated fractures.
Nonoperative Management¶
Reserved for Grade 1 (stable) and stable Grade 2 (partial disruption) injuries where no diastasis is visible on imaging.
• Acute Phase: Initial immobilisation and non-weight-bearing (often in a cast or CAM boot) for the first few days, typically progressing to protected weight-bearing by day seven.
• Rehabilitation: Focuses on restoring range of motion (ROM) and proprioception. Accelerated rehabilitation protocols are increasingly debated, emphasizing early loading while protecting the healing ligaments.
Operative Management¶
Indicated for Grade 3 (unstable) injuries, unstable Grade 2 injuries, and those associated with fractures (e.g., Weber B, Weber C, or Maisonneuve fractures).
• Reduction: The primary goal is anatomic reduction---aligning the fibula correctly within the tibial incisura---as malreduction is the strongest predictor of poor outcomes.
• Fixation Techniques:
◦ Rigid Fixation (Screws): Uses metallic or bioabsorbable trans-syndesmotic screws to immobilise the joint. Screws often require removal after 6--12 weeks to restore physiologic motion and prevent hardware breakage.
◦ Flexible Fixation (Suture Buttons): Uses a non-absorbable fiber wire construct (e.g., TightRope). This allows physiologic micromotion (pistoning and rotation) of the fibula and generally obviates the need for a second surgery for hardware removal.
• Return to Sport Continuum: The return to performance is a gradual process. For professional athletes, the mean time to begin on-field rehabilitation is approximately 37 days, with a return to official match play taking an average of 103 days post-surgery