Posterior ankle impingement causes pain in the back of the heel and is often misdiagnosed as Achilles tendonitis. In this article, we’ll look at what it is, how to diagnose it, and how to treat posterior ankle impingement without surgery. Remember, if you need help with an Achilles injury, you're welcome to consult one of our team via video call.
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What is posterior ankle impingement?
In short, it’s when something (bone or soft tissue) is pinched in the back of the ankle joint when you move. Let’s look at why this may happen.
The lower ends of the tibia (shin bone) and fibula form the ceiling of the ankle joint and the talus bone the floor. The talus sits on the calcaneus (heel bone).
When you perform plantar flexion – so, pointing your toes down or going up on your tiptoes – the bones that form the ankle joint move closer together at the back. Now, this is a normal movement, so why will this cause pain?
Causes of posterior ankle impingement
There are two main causes of posterior ankle impingement:
Overtraining in a sport or activity that repetitively force the ankle into strong plantar flexion.
Injuring your ankle and not allowing it to fully recover before resuming sport or activity.
The pain in the back of the ankle can be caused by the bones being compressed, soft tissue being compressed, or sometimes both.
Sports and activities that predisposes people to developing posterior ankle impingement include football, basketball, and ballet.
Cricket fast bowlers are the exception to the rule; they are prone to getting posterior ankle impingement through forced dorsiflexion (slamming the foot down as they bowl), causing the bones to slide and impinge in the back due to the force of the movement.
Bony abnormalities are only a part of the problem
When people complain of posterior ankle pain, and they scan their ankles, they often find abnormalities in the bones.
People may have an extra, loose little bone (called an os trigonum), bony spurs (osteophytes causes by arthritis), or a long, pointy talus (Stieda’s process). These have been blamed in the past for causing posterior ankle impingement.
However, these bony abnormalities are also found in people who have no ankle pain and are just as active. Also, the majority of people can recover from posterior impingement despite the extra bone still being there. So, why do they cause pain for some people and not others?
The current thinking is that, rather than causing the impingement, these bony structures may just make you more prone to it. It seems that you only develop symptoms if you do repetitive movement that strongly compress the back of the ankle or experience a traumatic event, e.g. your foot is forced into extreme plantar flexion while playing football.
Overuse causes
Sometimes the soft tissue that surrounds the ankle joint (e.g. the joint capsule or a tendon) gets pinched. Common reasons for this include:
Ongoing ankle instability, causing the joint to move too much; this often happens when someone has sprained their ankle and they have not properly strengthened it back up.
Thickening of the soft tissue due to ongoing irritation of either the capsule or tendons (especially the flexor hallucis longus and peroneal tendons); this is often caused through overuse (e.g. ballet dancers practising lots of en pointe) or if you don’t treat a sprained ankle properly.
Some people may have extra muscles in the area that get pinched; these are, however, also present in people without causing problems, so it is unclear whether these extra muscles are truly part of the cause.
A trauma event
If your ankle joint is forced into strong plantar flexion (like when you sprain it or just move it forcefully into that position) it can also injure the joint surface, causing injuries to the cartilage, bone, and soft tissue.
Similar to other injuries, this causes inflammation and swelling in the back of the ankle (as part of the healing process), resulting in impingement symptoms.
This type of impingement is the easiest to treat, because it just requires you to look after your ankle and allow it to calm down and heal. As soon as it has healed, the swelling goes down and the symptoms disappear.
How to diagnose posterior ankle impingement
Step One is to listen to the patient and check whether the symptoms they report fit the typical picture of posterior impingement.
The typical symptoms people report when they have posterior ankle impingement include:
Pain in the back of the ankle or heel; it usually feels deep, and it is often difficult to precisely pinpoint where it is coming from.
The pain can be described as sharp, dull, or radiating.
The pain is usually felt during or made worse by activities that require them to go up on their toes, forcefully push off, or where their foot has to move into strong plantar flexion, e.g. ballet, kicking in football, walking or running down hills, or wearing high-heeled shoes.
This is followed by a physical examination; we guide our patients through these tests via video call:
When you press in the area, it typically feels tender at the back of the ankle, above the heel bone, and behind the Achilles tendon. The tender area may be located more to the outer or inner back of the ankle.
When you move the ankle into passive plantar flexion (i.e. using your hands to move it so that the muscles and tendons remain relaxed), it usually reproduces the symptoms.
If passive movement of the big toe (bending it back) causes pain, the flexor hallucis longus tendon may also be injured.
Scans can be useful to confirm the diagnosis or to rule out more serious issues, but most cases can be diagnosed without them. The typical scans used include:
X-rays: They can show bony abnormalities, but they don’t show soft tissue or joint injuries. Also, just because you have a bony abnormality does not mean you have posterior ankle impingement, since 25% of uninjured people have them as well.
MRI scans: These are best for showing soft tissue injuries, fractures, bone marrow edema, cartilage injuries, etc.
CT scans: They are best for showing bony injuries that are sometimes difficult to see on X-rays.
Your physiotherapist will listen to how your injury started and how your symptoms are reacting and combine that with the results of the physical examination to decide whether a scan is needed and what type would likely be the most useful.
Things that can be mistaken for posterior ankle impingement
There are other conditions that can cause very similar pain to posterior ankle impingement. It is therefore important that your physio or doctor test for these as well:
Achilles tendon injuries, e.g. Achilles tendonitis or tears
Flexor halluces longus injuries
Ankle osteoarthritis
Injuries to the tibial and sural nerves
Referred pain from the lower back – L5, S1, or S2 nerve root irritation.
It is, of course, possible to have posterior ankle impingement in combination with any of these injuries as well.
Treatments for posterior ankle impingement
1. Stop aggravating it
If you want your ankle to calm down, you have to stop irritating it. In most cases, this doesn’t mean that you have to just sit on the couch and not do anything. It simply means that you should stop taking it into the positions that pinch the injured tissue or bone.
The only time someone requires total immobilisation is when they have a fracture.
Here are some ways to stay active:
Wear flat, but supportive shoes. Shoes with a heel place your ankle in a position that is more likely to pinch at the back. But the shoes must still provide support; most cases of posterior ankle impingement is accompanied by a bit of ankle instability, and a supportive shoe will help to stabilise your ankle while you build strength.
Avoid activities that increase your pain, especially sports and activities that take your ankle into plantar flexion. Depending on how aggravated your ankle is, you may still be able to maintain some fitness through activities that don’t involve much plantar flexion (like cycling or swimming using your arms only), but this will depend on how irritated your ankle is.
Taping your ankle to prevent it from moving into the painful range of motion can be useful, as it acts as a reminder to avoid those moves.
Some people may benefit from wearing orthotics in their shoe to provide extra support and limit excessive movement in the ankle.
Top tip: You’re much more likely to get good results if you allow your ankle to fully calm down (3 to 4 weeks) before starting to do more intense rehab.
2. Medication
There is always the temptation to reach for anti-inflammatory medication (like ibuprofen) to get the inflammation to calm down more quickly. But this may actually be counter-productive. The inflammation after an acute injury, like an ankle sprain, is actually a very important part of the healing process. It is therefore better to allow the inflammation to settle down in its own time.
Icing your ankle may be a better option if it is very painful. It also reduces the inflammation somewhat, but to a lesser extent and for a shorter time than medication.
If your ankle pain has been dragging on for more than a month despite being really good with not aggravating it and doing all the right rehab exercises, then you may benefit from trying anti-inflammatory medication or getting an injection.
An injection would usually consist of local anesthetic and corticosteriod. This can work really well to help the pain settle, but it can have unwanted side effects. So, it is best left as a last resort.
3. Exercises for posterior ankle impingement
Your physio will design your exercise plan according to what has contributed to your specific case. It will most likely include:
Exercises to strengthen the muscles around your ankle and improve your ankle’s stability.
Exercises that strengthen your core and the other muscles in your legs to improve your overall control and movement patterns.
Exercises that improve your ankle joint’s range of motion.
It is really important that these exercises be introduced at the correct time and pitched at the right intensity for your stage of healing.
For instance, you may have a stiff ankle joint, which means that you will likely benefit from exercises to improve your ankle’s range of movement. However, if you start doing these exercises too soon, when your ankle actually just needs to be left alone so it can calm down, it will just make it worse. Your physio will guide you in this.
4. Other injuries
If you also have other injuries (e.g. Achilles tendonitis), your treatment plan should include exercises for these. Your physio will have to adapt your Achilles rehab plan and your posterior ankle impingement plan so that the exercises you do for the one don’t aggravate the other.
5. Easing back into sport
Once your ankle has calmed down and you’ve regained enough strength and control in your ankle, it is time to slowly ease back into full training. Ramping up your training volume too quickly usually leads to reinjury, because your ankle can’t adapt fast enough to the new load.
6. Technique retraining
If your pain developed gradually over time, it may be worth looking at your technique in whatever sport or activity you do and checking whether anything that needs to be changed.
7. Surgery
Not everyone gets relief from conservative treatment, and surgery does seem to be effective, with studies reporting success rates of between 80% and 90%. Typically, surgery for posterior ankle impingement may involve removing extra bone and trimming soft tissue that is deemed to be excessive.
Posterior ankle impingement recovery time
There is a lack of high-quality research into recovery times for posterior ankle impingement, so we have to rely on case reports. It seems that the most realistic time for recovery from posterior ankle impingement when following a conservative treatment approach is 12 weeks.
In ballet, they seem to get good results when they reduce the dancer’s training for 3 to 4 weeks and then gradually rebuild the strength and control so that they return to full training and dance at around 12 weeks post-injury.
In one professional football (soccer) case study, they weren’t as patient. The club would allow 4 weeks to see whether a player’s pain would calm down. If it is not fully gone by then, they would opt for steroid injections, and if that does not produce results within 2 weeks (so, this is now 6 weeks post-injury), the next step is surgery.
This is silly, in my opinion, because there are very few of this type of injury that will heal within 4 weeks. I guess the big money involved in football plays a role in this decision process. It is worth noting that, at the time of writing, there was only this one study published, so maybe (and hopefully) it is not common practice.
With professional fast bowlers (cricket), it seems to depend on the total workload whether surgery is needed or not. Players who have bony abnormalities and play a lot of high-intensity cricket do not seem to get permanent relief from conservative treatment. The ones who have less intense training and competition schedules seem to react well to conservative treatment.
How we can help
Need help with your Achilles injury? You’re welcome to consult one of the team at TMA 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 Treat My Achilles 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
Maryke Louw is a chartered physiotherapist with more than 20 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.