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Non resolving achilles tendon pain – First things first - have I got the diagnosis correct?

Tendinopathy is not about age but about load accumulation - how much load has been placed on the tendon over time. Achilles tendinopathy can occur across the lifespan and across activity levels. A 13 year old gymnast can have pathology as can an 80 year old whose regular exercise is gardening and walking.

The Achilles tendon acts as a spring. Its largest loads are during plyometric activities where it is required to store and release energy. This places those athletes that are involved in running and jumping activities at greatest risk of suffering from tendinopathies. Whilst this is the case the Achilles tendon is loaded during everyday activities which is also why you don’t have to be an athlete to suffer from this condition.

Whilst this is the case there are some really important clues to listen out for or questions that you can ask your athlete/patient regarding their sporting history as the answers to these will likely give you greater insight into clarifying your diagnosis:

· Sporting history – this is essential as it tells us about whether they were/still are involved in sports that are at higher risk

· Level of sport – currently and previously – those athletes that suffer from tendinopathies are generally good athletes. They are for example the 40 year old who still runs 4minute kms, the midfielder in rugby whose change of direction is impressive, the basketballer with a great vertical jump and has been able to dunk since he was 15.

· History of activity level during the month prior to symptoms being felt is essential. We know that tendons hate change so what changed in the month leading up to their Achilles causing pain? Did they just return to sport following another injury? Was it the start of a new season? Increase in running volume? Alteration of running frequency? Started running uphill’s? Change in running surface from road running to trail or field running? Change in footwear to a lower pitch shoe?

· What part of their sport is most aggravating? Is it aggravated by compressive or tensile forces or a combination of both. For example a compressive force may be walking uphill, a tensile force sprinting on the flat and a combination force changing direction at speed or running uphill at speed. Combination forces are most irritating to tendons as they place them under the greatest load. Ensuring you are aware of which are most aggravating plays a key role in your education and management going forward including helping determine the starting point for rehabilitation, the addition or not of heel raises in shoes and much more.

· We also know that many people can continue to train and compete in their sport whilst suffering from tendinopathy. Whilst this is the case performance is commonly reduced so questioning around this aspect can be important in order to set realistic goals going forward.

· Is their achilles pain worse the day after high loads? If this is the case it is another clue to confirming tendinopathy is the likely cause. Tendon pain is dose dependent. The higher the load the greater the pain.

· Location of their pain is also important in assisting in your diagnosis. Achilles tendon pain is generally mid achilles or insertional achilles. Insertional achilles tendinopathy pain is localised to the distal attachment into the calcaneus. Mid achilles pain is generally pinpoint in nature so if the pain is diffuse, medial to the achilles or alternating sides consider differential diagnoses.

Remember that more than one of these pathologies can co-exist so unfortunately it is not always so “black or white”. Your athlete/patient may present with a combination of achilles tendinopathy and a peritendon issue or perhaps a long standing plantaris issue has led to compressive Achilles tendinopathy in addition to their original pathology. Remember that the majority of reactive tendons we see are likely to have a degenerative component underlying them. True reactive tendons without further pathology are less common than we think.

It is essential initially that red flags are ruled out. In patients with achilles pain inflammatory arthropathy should be screened for. Be aware of this in the patient who has severe symptoms, outside normal realm in comparison to load applied, bilateral symptoms, and symptoms that may be easily aggravated from low load. In this case complete an inflammatory screen and refer to a rheumatologist if you have ongoing concerns.

Differential Diagnoses


Paratenon inflammation is inflammation between the sheath and the Achilles. There is a paratenon only around Achilles tendon as the Achilles moves a lot around surrounding structures so it’s there for protection.

It is often reactive or very irritable pain. As a result of this low load activities may cause pain that would not cause pain in a mid achilles tendinopathy for example bilateral calf raises. This behaviour is similar to a true reactive tendon – for example a small bike ride might result in aggravation of pain for days.

Pain may be more medial or lateral unlike standard mid achilles pain. If medial pain consider plantaris also and if you are unsure an ultrasound may be needed here to differentiate these pathologies.

Paratenon issues are the result of friction, often large ranges of movement repeatedly for example during cycling or rowing. Poor technique or a bad setup and with a large amount of ankle dorsiflexion and plantarflexion are what irritates a paratenon rather than elastic storage exercises that aggravate the tendon itself.

This won’t behave like a normal tendon injury with load. There will be no dose dependent pain like plantaris or mid achilles tendinopathy as pain isn’t with energy storage but with friction in large ranges of motion. They don’t warm up with exercise, they tend to just get worse and movement or load doesn’t fix them unlike true tendon issues. As a general guide they can’t do calf raises as rehab as the range of motion aggravates them, even isometrics can be an issue as they bunch up the paratenon.

Crepitus is a sign of paratenon inflammation. In addition to this during objective assessment you may identify weak calves with poor stiffness that results in increased dorsiflexion range of motion during activity and therefore an irritated paratenon.

There may be low level or no pain when hopping on toes but hopping with the heel hitting the ground or a calf raise through full range of motion will be painful.

Unlike tendon issues you must settle this pain before loading. These often need anti-infammatory medication to do this. Alteration of load to reduce movement is essential including the removal of all aggravating factors and a gradual reintroduction of these as able.


The plantaris tendon can sit either inside or outside the achilles tendon sheath. Depending on how close it is to the achilles tendon you can get a compressive or friction load. Plantaris tendon issues hate dorsiflexion similar to insertional achilles tendinopathy. Dorsiflexion stretches plantaris and compresses the tendon against the achilles. Patients with plantaris pathology would rather be in shoes then barefoot because of this. Often plantaris pathology is bilateral with one side worse than the other at different times. If the patient complains that the pain “swaps” sides this is a clue that plantaris may be involved. If a patient complains that their pain is worse when running slow in comparison to running at faster speeds, consider plantaris as they are likely running with more dorsiflexion at slower speeds.

In comparison to fingers pointing to mid achilles pain they are likely to run fingers up the medial achilles and towards the musculotendinous junction.

During objective assessment ensure they complete a unilateral calf raise from floor scoring this on a VAS scale. Then complete a calf raise on full stretch off a step and again score using the VAS. If their pain is significantly aggravated off the step in comparison to the floor this points towards an issue with plantaris or an insertional tendinopathy. To differentiate the two, pain location is utilised.

Retrocalcaneal bursa

This coexists with insertional tendinopathy rather than being a sole pathology.

Clues for bursal involvement include diffuse pain, irritable pain, symptoms on low load activities and pain in dorsiflexion. This is very similar to plantaris pathology except for the location of pain which is the determining factor.

On imaging a small amount of fluid in the active population is normal but this is generally significantly greater in those with retrocalcaneal bursitis and can usually be observed during examination without imaging being required.

Sural nerve

In the person who hasn’t responded as expected to rehabilitation consider the sural nerve. Assessment of this includes ankle dorsiflexion with inversion then add in a straight leg raise and determine if this brings on pain.

The Sural nerve can get tethered locally perhaps in an athlete who has suffered a recent calf injury but also the lumbar spine may be the cause of irritation to this. Also consider in patients who have irritable pain, particularly with ankle dorsiflexion.

Partial tears

There is controversy regarding the true incidence of partial tears. In reality to have a true acute partial tear there must be an acute incident and significant increase in pain and reduction in function is related to that incident.. Otherwise, these are to be considered as part of the tendinopathy process and rehabilitated as such. Remember the use of language and the negative effects this can have on patients’ compliance, prognosis and overall outcome.

Accessory soleus

This is very rare but we must be aware of its existence. It is greater muscle bulk medial and lateral to the achilles and is actually a low soleus more than an accessory soleus. It is painful to palpate, worse with activity, doesn’t warm up and may present similar to “compartment syndrome”.

Fat pad

It is usually the mid portion achilles fat pad that is compressed rather than the distal. It is usually compressed in dorsiflexion from a thickened achilles, accessory soleus or abnormal plantaris. It may be more irritable and more difficult to warmup. Ultrasound may help differentiate.

When it comes to imaging is it necessary?

Ultrasound imaging of the Achilles is not required to confirm your diagnosis. It may be useful in assisting in differential diagnosis BUT remember that just because imaging findings are found does not mean they are the cause of your athlete/patients symptoms. Also remember partial tears do happen but they occur much less than we think, have very negative connotations to the patient and therefore these should be treated as part of the tendinopathy process. There is no criteria for these being diagnosed and therefore there is no reliability between radiographers for this diagnosis. Remember if you have pathology you are more likely to have symptoms but it doesn’t mean you have to have symptoms.

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