High Ankle Sprain (Syndesmotic Injury)

Quick answer

A regular ankle sprain tears the ligaments on the outside of the ankle (most commonly the ATFL). A high ankle sprain tears the syndesmosis — the ligaments and membrane that hold the tibia and fibula together just above the ankle joint. The mechanism, location of pain, and treatment are different from a regular sprain. The most important thing to recognize: high ankle sprains heal much more slowly and a fraction need surgery.

What’s actually injured

The ankle syndesmosis is held together by:

• Anterior inferior tibiofibular ligament (AITFL) — most commonly torn
• Posterior inferior tibiofibular ligament (PITFL)
• Interosseous ligament and membrane between tibia and fibula
• Inferior transverse ligament

A high ankle sprain damages one or more of these structures. If the injury is severe enough that the tibia and fibula spread apart (“diastasis”), it becomes a surgical problem.

Why it’s a different injury

A regular ankle sprain happens when the foot rolls inward (inversion). A high ankle sprain happens when the foot is planted and rotated outward — the talus rotates between the tibia and fibula and pries them apart. Common scenarios:

• A football player with their foot planted and another player falls across the back of their leg
• A skier whose ski twists outward in a fall
• A soccer player who plants and pivots

How to recognize it

• Pain above the ankle joint — over the syndesmosis, not the typical “lateral malleolus + below” spot
• Pain with squeezing the calf together (squeeze test)
• Pain with externally rotating the foot relative to the leg (Kleiger test)
• Pain with weight-bearing that doesn’t fit a regular sprain pattern
• Slower recovery than expected — a “sprain” that’s still painful at 4–6 weeks
• Often less swelling and bruising than a typical sprain, paradoxically

Diagnosis

• Clinical exam — squeeze test, external rotation test, palpation of the syndesmosis
• Weight-bearing X-rays — to assess for tibiofibular widening (diastasis); compare to the other side
• Stress X-rays — sometimes used to detect dynamic instability
• MRI — gold standard for ligament injury detail and to rule out associated injuries (osteochondral lesions, deltoid tear)
• CT scan — when fibular position needs precise assessment for surgical planning

Treatment

Stable injuries (no diastasis)

These are managed non-operatively but require patience:

• Non-weight-bearing or boot initially (typically 2–4 weeks)
• Progressive weight-bearing as pain allows
• Physical therapy for range of motion, strength, and proprioception
• Total recovery typically 6–10 weeks — about 2–3× longer than a regular ankle sprain
• Return to sport when single-leg hop, jump, and cutting tests are pain-free

Unstable injuries (diastasis or chronic)

Surgery is usually required to restore the tibiofibular relationship:

• Syndesmotic screw fixation — one or two screws placed between the fibula and tibia, often removed at 3–6 months
• TightRope (suture button) fixation — flexible synthetic suture and metal buttons; may not require removal; allows micromotion
• Ligament repair or reconstruction for chronic cases
• Recovery — non-weight-bearing for 6–8 weeks, then progressive weight-bearing and rehab over 4–6 months

Why early diagnosis matters

Untreated unstable high ankle sprains lead to:

• Chronic pain and instability
• Ankle arthritis from abnormal joint mechanics
• Worse outcomes even with delayed surgery

Athletes who try to “play through” a high ankle sprain often turn a 6–10 week injury into a season-ending one.

Bottom line

If an “ankle sprain” hurts above the ankle, takes longer to recover than expected, or happened with a rotational mechanism — get it imaged and assessed for a syndesmotic injury. Stable injuries respond well to extended boot immobilization and rehab. Unstable injuries need surgery. Don’t compare it to a regular sprain — high ankle sprains follow a different timeline and treatment path.