Posterior ankle impingement causes pain at the back of the ankle when pointing the foot downwards or in planterflexion. We can often confuse this condition with Achilles tendon pain. What causes posterior ankle impingement, and how do we diagnose and manage it?
Causes
Posterior ankle impingement occurs when there is pinching of structures at the back of the ankle, causing pain. Pinching occurs due to bone or soft tissue swelling or anatomical variations.
Bone causes include os trigonum, an abnormally elongated back of the talus called a Stieda process, bony spurs from ankle arthritis and fractures of bone. Examples of soft tissue causes include tendonitis and joint swelling after an ankle sprain.
How to diagnose posterior ankle impingement?
Several pain characteristics differentiate posterior ankle impingement from other causes of posterior ankle pain. First, pain occurs deep at the back of the ankle when pointing the foot downwards, also known as plantar flexion. Symptoms can appear suddenly after an ankle twist or gradually after repetitive plantarflexion activity such as dancing or football.
It is essential to differentiate posterior ankle impingement from other causes of posterior ankle pain. For example, Achilles tendonitis, posterior tibial tendonitis, accessory soleus muscle and Kager’s fat pad oedema can cause pain at the back of the ankle.
Generally, we also find ankle joint movement restriction. Sometimes, swelling can occur at the back of the ankle surrounding the Achilles tendon.
Posterior ankle impingement test
Forcing the ankle into full plantarflexion causes pinching at the back of the ankle and reproduces pain. However, we don’t know how sensitive this test is in diagnosing posterior ankle impingement.
Generally, we diagnose the cause of posterior ankle impingement by using imaging. X-rays of the ankle show bony causes of posterior impingement of the ankle, such as Os trigonum, Stieda process, loose bodies and bony spurs. MRI scans demonstrate soft tissue causes such as joint swelling or soft tissue impingement.
Posterior ankle pain treatment
We always start with conservative management. Activity modification is essential to reduce provocative activities. Regular oral NSAIDs such as ibuprofen will help reduce swelling at the back of the ankle. Physiotherapy is an underrated treatment and should be employed to minimise pinching at the back of the ankle. Your therapist should use various techniques, including soft tissue massage and joint mobilisation. Also, strengthening the muscles surrounding the ankle joint will reduce pinching.
Injections for posterior ankle pain
In persistent cases of posterior ankle pain, a cortisone shot directed to the area of swelling at the back of the ankle is helpful. Generally, we suggest an ultrasound-guided injection to improve accuracy and reduce side effects.
Surgery
We should only recommend surgery in cases that fail conservative treatment, including injections. Open or arthroscopic techniques are available.
Generally, surgeons excise bone and soft tissue causes of posterior ankle impingement. So, os trigonum can be removed simultaneously as joint swelling or synovitis. Overall, it is crucial to understand that surgery involves a long recovery time – often 3-6 months- and should not be taken lightly. Also, removing bone causes of posterior impingement, such as an os trigonum, might increase the risk of arthritis from an uncovered calcaneus at the back of the subtalar joint. A study examining outcomes after os trigonum excision found a 13-14% complication rate, primarily due to the development of postoperative subtalar arthritis,
Final word from Sportdoctorlondon regarding posterior ankle pain
Posterior impingement causes pain at the back of the ankle. It can be confused with other conditions, such as Achilles and tibialis posterior tendonitis. You should see an experienced sports doctor for a correct diagnosis and management.
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