A high ankle sprain — formally a syndesmotic ankle sprain — is an injury to the ligaments that hold the tibia and fibula together above the ankle joint. Unlike the much more common lateral ankle sprain (which involves the ATFL and CFL on the outside of the ankle), a high ankle sprain injures the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), and interosseous membrane — structures critical for maintaining the integrity of the ankle mortise. High ankle sprains take 2–3 times longer to heal than lateral ankle sprains, have a high rate of incomplete recovery without proper treatment, and are frequently diagnosed late because the initial presentation can be subtle. At Balance Foot & Ankle in Howell and Bloomfield Hills, MI, Dr. Tom Biernacki, DPM accurately diagnoses and manages the full spectrum of syndesmotic injuries.

What Is the Syndesmosis and Why Does It Matter?

The ankle syndesmosis is the fibrous joint connecting the distal tibia and fibula at the ankle — the mortise that cradles the talus. The syndesmosis is stabilized by four ligaments: the AITFL (most commonly injured in high ankle sprains), the PITFL, the transverse ligament, and the interosseous membrane that runs the full length of the tibia-fibula relationship. Together, these structures maintain the precise width of the ankle mortise — even 1mm of tibiofibular diastasis (widening) increases contact stress in the ankle joint by 42%, accelerating cartilage wear and arthritis. This is why syndesmotic injuries that are not properly managed lead to chronic ankle pain and early ankle arthritis, whereas well-treated injuries can achieve full recovery.

Mechanism of Injury — How High Ankle Sprains Happen

High ankle sprains occur through external rotation and dorsiflexion mechanisms — the talus rotates within the mortise and forces the tibia and fibula apart. Common scenarios include: landing from a jump with the foot externally rotated (basketball, volleyball, gymnastics); being tackled with the foot planted and the body rotating over it (football, rugby); and catching the foot in a cleat on artificial turf while the body rotates (soccer, lacrosse). High ankle sprains are particularly common in ice hockey — the forward falling motion with the skate blade planted creates the external rotation force perfectly. They account for approximately 10–15% of all ankle sprains but represent a disproportionate share of significant time-loss athletic injuries because the recovery time is two to three times longer than a comparable-severity lateral sprain.

Symptoms — How It Differs from a Lateral Ankle Sprain

The key clinical features that distinguish a high ankle sprain from a lateral ankle sprain: pain is located anteriorly above the ankle joint line rather than below the lateral malleolus; walking is more severely impaired relative to the apparent swelling (lateral sprains often produce dramatic swelling; high ankle sprains may have modest swelling but profound walking difficulty); pain is reproduced by squeezing the tibia and fibula together at mid-calf (the “squeeze test”) — this is the most specific clinical test for syndesmotic injury with a specificity of approximately 88%; external rotation stress test (rotating the foot externally with the knee flexed) reproduces the mechanism and provokes pain; and the Cotton test (anterior-posterior drawer of the talus relative to the tibia) is positive when tibiofibular diastasis is present. In our clinic, any ankle sprain in an athlete that causes more walking difficulty than expected for the visible swelling should be considered syndesmotic until proven otherwise.

Imaging — Weight-Bearing X-Rays and MRI

Standard ankle X-rays can demonstrate tibiofibular diastasis in complete syndesmotic injuries — widening of the tibiofibular clear space (greater than 6mm) on AP view or loss of tibiofibular overlap (less than 10mm on AP or less than 1mm on mortise view). However, partial syndesmotic sprains with intact diastasis on plain X-ray are common, and weight-bearing stress X-rays may be necessary to demonstrate instability under load. MRI is the most sensitive and specific modality for diagnosing syndesmotic ligament injury, grading tear severity, and identifying concomitant injuries (osteochondral lesion of the talus is present in up to 30% of syndesmotic sprains). CT scan quantifies mortise widening and identifies associated fibula fractures more accurately than X-ray. In competitive athletes, MRI is the recommended imaging modality when clinical findings suggest syndesmotic injury.

Conservative Treatment — For Stable Syndesmotic Sprains

Stable high ankle sprains — those without diastasis on weight-bearing or stress X-ray — are managed conservatively with a significantly more prolonged and structured protocol than lateral ankle sprains. Immobilization in a CAM walker boot is typically required for 4–6 weeks (compared to 1–2 weeks for a Grade II lateral sprain), followed by a formal rehabilitation program emphasizing peroneal and tibialis anterior strengthening, external rotation resistance training, and proprioceptive retraining. Early weight-bearing is permitted in the boot, but return to sport is delayed until single-leg heel rise is pain-free, the squeeze and external rotation stress tests are negative, and functional performance testing (single-leg hop, agility testing) is within 90% of the uninjured side. Average return to competitive sport for a stable Grade I–II syndesmotic sprain is 4–8 weeks compared to 1–3 weeks for a comparable lateral sprain.

Surgical Treatment — For Unstable Injuries

Unstable syndesmotic injuries — those with diastasis on weight-bearing X-ray or stress testing — require surgical stabilization to restore and maintain mortise anatomy. Surgical options include temporary syndesmotic screw fixation (one or two cortical screws traversing the fibula and tibia to maintain reduction while the ligaments heal, removed at 3–4 months), suture-button fixation (a flexible fixation system using a braided suture and cortical buttons that maintains reduction while allowing slight physiological motion and does not require routine removal), and acute direct ligament repair for acute complete tears with adequate tissue quality. Suture-button fixation (devices such as Tightrope) has largely replaced screw fixation at experienced centers due to the elimination of mandatory hardware removal, lower implant failure rates, and equivalent or superior clinical outcomes. Recovery from surgical syndesmotic fixation follows the same timeline as post-fracture ankle surgery: non-weight-bearing for 4–6 weeks, boot walking for 4–6 weeks, physical therapy, and return to sport at 4–6 months.

Red Flags — When to Seek Same-Day Evaluation

Seek same-day evaluation for an ankle injury if: pain is located above the ankle rather than on the outside of the ankle (possible high ankle sprain requiring X-ray for fibula fracture and diastasis assessment); you cannot bear weight after the injury; the injury occurred in a contact sport with an external rotation mechanism; the ankle area (above the ankle on the inner leg) is tender when squeezed from the sides; you had previous ankle surgery involving screws or plates and now have re-injury in the same ankle; or you are a competitive athlete and cannot afford an extended recovery from a mismanaged sprain.

Treatment at Balance Foot & Ankle — Michigan

Dr. Tom Biernacki, DPM evaluates all ankle sprains with Ottawa Ankle Rules, in-office weight-bearing X-ray, squeeze test, external rotation stress test, and Cotton test to accurately distinguish high ankle sprains from lateral sprains. MRI coordination, conservative management, and surgical fixation for unstable injuries are all available. Appointments at our Howell office (4330 E Grand River Ave, Howell MI 48843) and Bloomfield Hills office (43494 Woodward Ave #208, Bloomfield Hills MI 48302). Call (810) 206-1402 or

book online for same-day assessment.