Syndesmosis Injury (High Ankle Sprain)
The syndesmosis is the strong fibrous joint that binds the two bones of the lower leg — the tibia and the fibula — together just above the ankle. An injury here is often called a high ankle sprain, because the pain sits above the ankle joint rather than around its outer side.
High ankle sprains behave differently from the common ankle sprain. They take longer to heal, they are easier to miss, and a proportion are unstable and need surgery to protect the ankle joint. Working out which kind you have is what matters most.
What is the syndesmosis?
Three ligament structures hold the fibula snugly against the tibia: one at the front, one at the back, and a sheet of tissue between the bones. Together they keep the socket of the ankle gripping the talus precisely. The ankle depends on that exact fit — even a few millimetres of widening changes how load passes through the joint surface, which is why unstable injuries are taken seriously.
How does a high ankle sprain happen?
The usual mechanism is the foot being planted while the body twists outwards over it, or the ankle being forced sharply upwards — common in football, skiing and tackles. This is different from the common sprain, where the foot rolls inwards and injures the ligaments on the outer side of the ankle.
Syndesmosis injuries also occur alongside some ankle fractures, where they are assessed and treated as part of the fracture surgery.
Symptoms
Pain above the ankle joint: Felt between the shin bones, higher than a typical sprain.
Pain on push-off: Climbing stairs, pivoting or rising onto the toes is often what hurts most.
Pain on squeezing the leg: Compressing the two leg bones together higher up the calf can reproduce the pain at the ankle.
Difficulty hopping: Many people simply cannot hop on the injured leg.
Deceptively little swelling: The ankle can look better than it feels, which is part of why these injuries are missed.
Diagnosis
Examination points to the diagnosis; imaging confirms it and, more importantly, establishes whether the joint is stable:
Weight-bearing X-rays: Taken standing, sometimes of both ankles for comparison, to look for widening between the tibia and fibula.
Stress views: X-rays taken while the ankle is gently stressed, to reveal instability that plain films miss.
CT: Shows subtle widening or rotation of the fibula in fine detail.
MRI: Shows the ligaments themselves and any associated cartilage injury.
Arthroscopy: In selected cases the syndesmosis is inspected directly with a keyhole camera — ankle arthroscopy — which is a highly accurate way of confirming whether the joint is unstable, and is usually done at the same operation as the fixation.
Stable or unstable: the decision that matters
In a stable injury the ligaments are partly injured but the bones remain correctly held. These are treated without surgery — usually a period in a walking boot with weight-bearing as advised, followed by physiotherapy. Recovery is genuinely slower than a common sprain, and expecting a normal sprain timeline is the main source of frustration with this injury.
In an unstable injury the fibula is no longer held firmly against the tibia, and the joint widens under load. These generally need surgery, because a widened ankle concentrates load on a small area of cartilage and, left alone, is a recognised route to ankle arthritis.
Surgery
The aim of surgery is to restore the exact relationship between the fibula and tibia and hold it while the ligaments heal. The two established methods are screws passed across the two bones, and a flexible suture-button — a strong cord anchored by a small metal button, which holds the bones together while allowing a small amount of their natural movement.
Dr Janan offers both, and generally uses the flexible suture-button option because it maintains the normal subtle movement between the two bones while the ligaments heal. Which method suits your injury is discussed with you beforehand. With either method, the hardware generally does not need to be removed later.
Where the syndesmosis injury is part of an ankle fracture, it is fixed at the same operation.
Recovery
Recovery is staged and slower than for a common sprain:
Early weeks: The ankle is protected in a boot, with weight-bearing introduced as advised. Elevation helps considerably.
From around six weeks: Transitioning out of the boot into supportive footwear, with physiotherapy to restore movement, strength and balance.
Return to sport: For stable injuries this is commonly measured in weeks to a couple of months; after surgical fixation it is commonly three to four months or more, guided by strength and confidence rather than the calendar alone.
What if it is missed or left untreated?
An unrecognised syndesmosis injury can cause ongoing pain above the ankle, a sense of the ankle giving on push-off, and — where the joint has been left widened — arthritis developing over the following years. Late treatment is possible but more complex than early treatment, which is why a "sprain" that is not following the normal script is worth reassessing rather than pushing through.
Dr Janan’s approach
Dr Janan Chandrananth completed fellowship training in Bristol, a major United Kingdom foot and ankle centre, and in Tokyo under Professor Satoru Ozeki, past president of the Japanese Society for Surgery of the Foot. He assesses both acute high ankle sprains and sprains that have failed to settle, treats stable injuries without surgery, and performs fixation where the joint is unstable.
Pain above the ankle, or a sprain that is not settling?
Book a consultation with Dr Janan Chandrananth to have your ankle assessed — early diagnosis keeps the treatment options simple.
FAQs
How is a high ankle sprain different from a normal ankle sprain?
A normal sprain injures the ligaments on the outer side of the ankle when the foot rolls inwards. A high ankle sprain injures the syndesmosis — the joint between the two leg bones above the ankle — usually from a twisting or upward force. The pain sits higher, push-off hurts more than walking, and healing takes longer.
How long does a high ankle sprain take to heal?
Longer than most people expect. A stable injury commonly needs around six weeks of protection before rehabilitation progresses, where a mild common sprain settles in two to three. Unstable injuries treated with surgery are measured in months. Slow progress is normal for this injury and not a sign something has gone wrong.
Do all high ankle sprains need surgery?
No. Some are stable and heal well with a boot and structured rehabilitation. Surgery is for injuries where the joint between the tibia and fibula has widened or is unstable/painful under load.
Will the metalwork need to come out?
Generally not. Whether a flexible suture-button or screws are used, the hardware is usually left in place permanently and causes no problems. Removal is only considered in the uncommon situation where the hardware becomes irritating, and that would be discussed with you at the time.
When can I return to sport?
After a stable injury, generally once strength, balance and push-off are back to normal — often around two to three months. After surgical fixation, return to running and sport is commonly three to four months or more. Rushing this step is the main cause of setbacks.
Can it be treated if it was missed months ago?
Often yes, but treatment is more involved — the joint may need to be cleared of scar tissue and re-stabilised, and where arthritis has already developed the options change. This is a further reason to have a slow-to-recover sprain assessed rather than waiting.
Not sure whether it is broken? Wondering how a sprain is told apart from a fracture? What’s the Difference Between a Sprain and a Fracture? explains the warning signs and when an X-ray is needed.