Posterior Ankle Impingement
Posterior ankle impingement (PAI) is a condition seen commonly in athletes who present with pain in the back of their ankle.
This is caused by compression of bone or soft tissues in the ankle during plantarflexion (pointing your toes to the floor). It can also be known as posterior impingement, Os trigonum syndrome or dancer’s heel.
The ankle, or talocrural, joint is made up of 3 bones; the tibia, fibula and talus, which work as a hinge joint. All joint surfaces surfaces are covered in articular cartilage which helps them to glide over each other smoothly and cushion impact during activities.
Surrounding these joints is a capsule which contains synovial fluid to provide lubrication, nutrition and protection to the joints.
On the outside of the joint capsule the ankle is reinforced by ligaments on the medial and lateral aspects and further by the tendons of muscles arising from the leg and foot.
At the back of the ankle, a small percentage of the population has an anatomical variation known as ‘Os Trigonum’. This is a small, loose, sesamoid bone found off the back of the talus that is usually painless but can become painful when aggravated.
During plantar flexion (when the foot is pointed away from the body) the back of the ankle is compressed. This movement doesn’t usually present a problem unless the forces through the back of the joint are excessive, such as when increased load is applied or the movement is repeated excessively, or if there is a combination of these factors. When this occurs the back of the tibia compresses the back of the talus, or the soft tissue between these two bones, resulting in a sharp pinching pain.
PAI is commonly seen in active populations who are regularly plantar flexing the foot such as ballet dancers, gymnasts, football players or cricket fast bowlers who often land hard on their front leg. It occurs as the bone, or soft tissues, in the back of the ankle are pinched excessively during plantar flexion causing pain and inflammation. The most common structures involved are the joint capsule, the flexor hallucis longus tendon or the os trigonum.
This condition is frequently seen in people who have had inversion sprains of the ankle and not undergone correct rehabilitation, resulting in chronic instability and an increased likelihood of structures becoming compressed. Athletes who are found to have this condition may attempt to compensate for the pain by changing their stance or gait by inverting the foot which can increase the chances of developing other injuries such as ankle sprains, calf strains or plantar fascia pain.
Symptoms of PAI include:
· Sharp pain at the back of the ankle joint during activities that require plantar flexion (pointing)
· Ache at rest or following provocative activities (kicking, jumping and running/walking particularly downhill)
· Swelling through the back of the ankle
· Joint line tenderness across the back of the ankle that doesn’t involve the Achilles tendon
PAI is most commonly treated with conservative care and will usually heal well with this course of treatment.
Conservative care involves four main phases of treatment:
· Phase 1: Aims to manage the pain, reduce swelling and aggravation of the injury. During this phase your physio, chiro or massage therapist will provide advice to reduce the strain on the area. This will include relative rest which involves avoiding the aggravating the plantar flexion movement. Other treatment modalities in the first phase may include: anti-inflammatory medication, ice, compression and elevation of the affected ankle. Electrotherapeutic agents such as ultrasound and manual therapy techniques including mobilisation, dry needling, and soft tissue massage and in advanced cases the temporary use of an immobility aid (e.g. brace) to off-load the injured structures.
Phase 2: Involves restoring the loss of movement incurred from the injury itself and any other losses due to partial mobilisation. Once pain has reduced enough your therapist will start you on a progressive range of stretches and exercises to improve the mobility in the lower leg and foot. These exercises begin with calf stretching, range of motion exercises moving in all directions and isometric calf holds. Your therapist will also add some low level proprioception activities to reduce instability at the ankle joint. During this phase they will continue to address any remaining stiffness in joints or surrounding muscles
· Phase 3: Begins when pain has been eliminated and ROM has been restored to pre injury status. This phase involves building strength in the calf, ankle and foot muscles. This is the most important phase as it will provide dynamic ankle support and control, to minimise the risk of recurrent injury. These exercises begin in a non-weight bearing position and progressively move to more functional positions with increased loading. Thigh, gluteal and core strengthening will also be included to build global support to the area and proprioception will be progressed to further enhance ankle stability.
· Phase 4: The 4th and final phase is managing a return to sport or activity. This is done in a progressive way, with a gradual return to light training, before increasing intensity to facilitate a return to peak performance.
In people where conservative treatment hasn’t been effective, further treatment options are available. This may include corticosteroid injection into the area to reduce pain and inflammation or surgical intervention. Surgery is usually the last option and involves the removal of bone spurs in the posterior ankle which form due to the stress placed on the joint.
3 tips to help try and avoid the onset of posterior ankle impingement are:
1. Maintain good strength and proprioception to avoid excessive movement at the ankle, particularly inversion ankle sprains.
2. Avoid excessive dorsiflexion or plantarflexion to reduce stress on the posterior ankle.
3. If you compete in sports that have higher rates of PAI and are getting pain in the ankle seek help from a therapist as quick as possible as this will dramatically reduce your time away from sport.
So that’s a brief overview of how posterior ankle impingement can occur. If you have any questions or comments please e-mail us at firstname.lastname@example.org and we will be happy to answer them for you.
If you suffer with pain through the back of the ankle, feel free to call us on (08) 9486 8653 and our therapists will be happy to chat with you about the best management plan.