Updated: Oct 17
It’s important that high ankle sprains (also called syndesmosis sprains) be identified correctly, because their treatment differs somewhat from other types of ankle sprain. If this is not handled correctly, it can lead to chronic ankle instability. This article covers the symptoms and diagnosis of high ankle sprains, as well as their grading and treatment, and what the recovery times might be. Remember, if you need more help with an injury, you're welcome to consult one of our physios online via video call.
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This article is about high ankle sprains, which should not be confused with the more common ankle sprains that injure the medial (inner) and/or lateral (outer) ankle ligaments and require different treatment.
Anatomy of the syndesmosis joint
The ankle joint comprises your two shin bones – the tibia and the fibula – and the talus bone in your foot, upon which the shin bones rest, as well as the various ligaments that hold the shin bones together and join them to the talus. Then there’s the interosseous membrane, which runs between the tibia and fibula all the way up to just below the knee, and which also helps to keep these two bones together.
The syndesmosis joint is between the lower ends of the tibia and fibula. A syndesmosis or high ankle sprain is when you tear the ligaments and interosseous membrane that hold the lower parts of these two bones together.
Why it’s important to identify a syndesmosis sprain correctly
Almost all of your body weight goes through your tibia and fibula when you stand, walk, run, and jump; so it can have serious consequences if you have instability between these two bones and/or between them and the talus bone.
If a high ankle sprain isn’t rehabbed properly or, in the case of a Grade 4 sprain, if it’s not fixed successfully with surgery, it can lead to chronic instability and pain in the lower leg and ankle.
This type of ankle sprain also takes longer to recover (see the section on high ankle sprain recovery times below) than the more common sprains lower down the ankle, and this is especially something to be aware of in rehab management.
High ankle sprain symptoms and diagnosis
Mechanism of injury
The first clue that an injury might be a high ankle sprain is if it happened in the following way: the foot was forced upwards, towards the shin bone (dorsiflexion) and then the lower leg twisted inwards. This doesn’t always cause a high ankle sprain, but a severe case of this movement is how it usually happens.
A typical example in football/soccer is when someone plants their non-kicking foot firmly on the grass just before kicking the ball, and then they get tackled.
The next step in the diagnosis process would be to replicate the movement described above. So, the physiotherapist would take the foot, move it into dorsiflexion (bend it upwards), and then twist it outwards. If this causes the patient pain, it’s very likely that it is a high ankle sprain.
The next test is to squeeze the tibia and the fibula together at mid-calf level; this will cause them to want to separate lower down, placing strain on the ligaments that connect them. If this hurts, it’s another strong indication that the patient has a high ankle sprain, and also that the injury might take longer than usual to recover.
The last hands-on test is to press along the line between the tibia the fibula where the interosseous membrane runs and also over the front of the ankle where the anterior inferior tibiofibular ligament sits; if the patient reports pain, it’s another sign of this injury.
Because everything in the ankle is usually painful and sensitive directly after an injury happened, it is be better to wait about five days before doing these tests; they are more accurate and yield more information at that stage.
What about scans? X-rays don’t show up damage to soft tissue such as ligaments, and in most cases they won’t show the tell-tale gap between the tibia and the fibula. However, they can be useful to see whether any bones have been broken in the incident that caused the high ankle sprain. MRI and CT scans are better for diagnosing high ankle sprains and for grading them (see below).
However, if you don’t have access to these scans, the hands-on tests are usually sufficient for a correct diagnosis.
Grading of high ankle sprains
The grading system I’m discussing here is the one they use when interpreting MRI scans, and it goes from Grade 1 to Grade 4.
Grade 1: The ligament that ties the tibia and the fibula together over the front of the ankle – the anterior inferior tibiofibular ligament – is the only one that’s injured.
Grade 2: Like Grade 1, and the interosseous membrane – the bit that runs between the tibia and fibula – is also injured.
Grade 3: Like Grade 2, and the ligament that ties the tibia and fibula together round the back of the ankle – the posterior inferior tibiofibular ligament – is also injured. This little ligament is responsible for 42% of the strength of the whole syndesmosis joint, so if the injury to it is significant, things are getting quite serious.
Grade 4: Like Grade 3, and you’ve also injured the deltoid ligament – so, the one that runs on the inside of the ankle – and the joint is very likely now quite unstable.
A football/soccer player who gets a Grade 1 high ankle sprain is usually able to get up and continue playing, and then the pain sets in after the match. If the player has to come off the pitch, it is usually a Grade 2 sprain or worse.
High ankle sprain treatment
Conservative treatment vs. surgery for high ankle sprains
Grade 1 to 3 high ankle sprains can usually be treated conservatively, i.e. you rehab the injury with the right combination of rest and strengthening exercises. With Grade 4 sprains, you would usually have to get a surgeon involved to first stabilise the joint, after which you would rehab it.
Severe Grade 3 sprains might also need surgery, but it's always best to try conservative treatment first, and if you find that that doesn't work, then consider surgery.
The treatment regime for high ankle sprains is similar to that of other types of ankle sprain, with one major exception: avoid dorsiflexion.
Bending the foot upwards naturally makes the bottom ends of the tibia and fibula want to move away from each other. So, if the ligaments that are supposed to hold them together are injured, this movement is going to stretch them and injure them even further, and they won’t heal.
With most other ankle sprains, it’s the ligaments on the outside and/or the inside of the ankle that are injured, so dorsiflexion doesn’t affect them that much.
This doesn't mean that you should avoid dorsiflexion for ever – just during early rehab. How long to avoid it for will depend on the grade of your sprain. For instance, in a study on the treatment of high ankle sprains in professional footballers, they avoided dorsiflexion for only a few days for a Grade 1 sprain, whereas they avoided it for four weeks for Grade 3 and 4 and then re-introduced it very gradually, being guided by what the ligaments would tolerate.
First three to five days
Be as kind to your ankle as possible and apply the classic PRICE regime for injuries: Protect, Rest, Ice, Compression, Elevation – anything you can do to help the swelling and the pain to calm down.
Avoid using anti-inflammatory drugs or rub-ons. Inflammation plays an important part in the body’s natural healing process. In this case, it helps with getting rid of the damaged ligament fibres and replacing them with new ones.
Like dorsiflexion, putting weight on your foot naturally wants to make the bottom ends of the tibia and fibula move away from each other, and this puts strain on the ligaments that are supposed to keep them together.
So, you need to start with partial weight-bearing, using crutches, and then gradually progress to putting more and more weight on your foot. How much weight and when should be determined by how much your injured ligaments can take without too much pain.
If you don’t have the luxury of an MRI scan to see the exact amount of damage to the ligament(s), wait a week or two after the injury before you begin with this process.
Use crutches to take all weight off the injured ankle initially, and then gradually add some bodyweight as you go along.
If you have access to a swimming pool, it’s a very good way to do walking, heel raises, and balance exercises while only putting some weight on the injured ankle. Not many of us have access to an anti-gravity treadmill, but that would also be useful.
Strengthening the muscles that support the ankle
The classic calf strength exercise is to go up and down on your toes. However, if you’re still in the partial weight-bearing phase, obviously you can’t be doing this yet, especially not on the injured leg only. So initially, it would be better to use exercise bands or do gentle isometric presses with your foot in plantar flexion (pointing down).
The same goes for your invertor muscles – the muscles that turn your foot in an out – because they also help to stabilise your ankle. Again, an exercise band is the way to go here.
High ankle sprain taping
A regular ankle brace doesn’t help for high ankle sprains, because it only stabilises the ankle against sideways movement. What you want is to support the ligaments by keeping the bones of the joint together.
So, you’ll notice on the picture how they are taping strips around the ankle to keep the lower ends of the tibia and the fibula together (top two photos).
And then they add some heel-lock taping to that to support the deltoid ligament on the inside of the ankle (bottom two photos).
Balance and proprioception
Proprioception is the ability to know where a limb or other body part is without having to look at it. Our brains depend on signals being sent by receptors from various parts of our body for balance and proprioception.
When we get injured, these signals get muddled to a certain extent, which diminishes our balance and proprioception. It is important to restore this, because poor balance and proprioception put us at risk of re-injuring ourselves once we start with our normal activities and sport again.
Fortunately, this is very easy to retrain through various balancing activities. However, like with the calf muscle exercises, it’s obviously not a good idea to try and balance on your injured leg before the injury has recovered somewhat. In the meantime, the swimming pool is a good place for balancing exercises.
Once you’re out of the pool with your balancing exercises, make sure that you can properly balance on flat surfaces before you start thinking of balancing exercise aids like wobble boards.
Running and plyometrics
Once your ankle has recovered enough for you to run again, start with running in a straight line to save the recovering ligaments from having to deal with twisting forces.
If your sport requires you to change direction quickly, like football/soccer, you’ll have to add in drills for these at a later stage, but at that point your ankle has to be really strong and pain-free.
If your sports also involves jumping, like basketball, you’ll have to add in plyometric exercises, with the same caveat as above. This article has some examples of plyometric exercises, with video demos.
High ankle sprain recovery timelines
Recovery times for high ankle sprains among us mere mortals are not very well-researched.
This is what they found in the study on the professional footballers: Players with a Grade 1 sprain lost about a week of full-on training. Move on to Grade 3, and players lost out on about ten weeks of active play.
Bear in mind that if you’re not in an elite football team, you probably won’t have access to the level of daily input and monitoring that these players have, so you might well take somewhat longer to recover from your high ankle sprain.
Because high ankle sprains can so easily cause ongoing ankle pain and instability, it is better not to rush and rather be super conservative with how quickly you progress your rehab.
How we can help
Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Sports Injury Physio we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Sikka, R. S., Fetzer, G. B., Sugarman, E., Wright, R. W., Fritts, H., Boyd, J. L., & Fischer, D. A. (2012). “Correlating MRI findings with disability in syndesmotic sprains of NFL players” Foot & Ankle International, 33(5), 371-378.
Calder, J. D., et al. (2016). "Stable versus unstable Grade II high ankle sprains: a prospective study predicting the need for surgical stabilization and time to return to sports" Arthroscopy: The Journal of Arthroscopic & Related Surgery 32(4): 634-642.