Achilles tendinopathy is an inflammation of the Achilles tendon and occurs in 2-3 in 1000 people. Athletes comprise 2/3rd of those who develop tendinopathy. Remarkably, the remaining 1/3rd are sedentary individuals. Stressing the Achilles tendon too little (sedentary) or too much (intense sports) plays an important role in this (Järvinen et al., 2005; van der Vlist et al., 2019).
In some athletic populations, up to 50% of athletes experience an episode of Achilles tendinopathy (van der Vlist et al., 2021). This makes it one of the most common running-related conditions. As many as 43% of long-distance runners report having symptoms (Kakouris et al., 2021; Silbernagel et al., 2020).
Cause of pathology
Achilles tendinopathy results from overuse of the Achilles tendon. The Achilles tendon forms the attachment to the foot of 2 major calf muscles (gastrocnemius and soleus). The tendon consists of several collagen fibers that in a healthy state are structured to form a strong structure. Loading the muscle affects the organization of the collagen fibers. Due to repetitive overloading, the tendon is unable to recover sufficiently from the load resulting in degeneration of the tendon (Maffulli et al., 2020). This degeneration reduces the quality of the tendon due to a disorganization of collagen fibers (Magnan et al., 2014) which reduces tendon stiffness (Silbernagel et al., 2020). As a result, the force transmission of the tendon is reduced, small tears can develop, and if left untreated, tendon rupture.
There are two types of tendinopathy depending on the location of the symptoms (Silbernagel et al., 2020):
- At the level of the insertion with the heel bone: insertional Achilles tendinopathy (20-25%)
- In the middle of the tendon: mid-portion Achilles tendinopathy is most common (55-65%)
There are also several risk factors that increase the risk of tendinopathy. The most important ones can be found in the table below (van der Vlist et al., 2019).
External risk factors:
- Limited mobility of the ankle joint
- Alcohol consumption, smoking
- Physical activity level
- Exercising during cold weather
- Aberrant gait pattern, reduced forward propulsion
Intrinsic risk factors:
- History of previous fracture
- History of previous tendinopathy
Evolution of the pathology
The natural recovery of a tendinopathy can take up to 12 months after the repair process has begun. Achilles tendinopathy follows the phases of general connective tissue repair. The first phase is the inflammatory phase, where our body responds to the damage. This is where we see pain, swelling and pressure sensitivity. This is where the body begins the repair process. This inflammatory phase lasts about a few days to a week and a half. This is usually when the patient comes in contact with the doctor or physical therapist. The second phase is the proliferation phase. In this, new tissue is formed. This phase can already start during the inflammation phase and takes about 3 weeks. The third and final phase is the regeneration phase. This phase can take from 3 months to 1 year. Here the goal is to give the newly formed tissue a final structure. Proper therapy during this period is important to give the tissue a quality structure. The tissue must be progressively loaded here, so active participation is essential at this stage. Depending on the severity, the stage of the tendinopathy and the load capacity of the tissue, we see that a functional recovery takes 6-10 weeks. This means that general daily activities are complaint-free, such as walking without pain. With a more sport-specific request for help, we see that this takes longer, 3-6 months approximately.
The most common symptoms in Achilles tendinopathy are (Silbernagel et al., 2020):
We will go into a little more detail by type of symptom.
At the level of the joint or articular
Due to stiffness or swelling, there may be reduced ankle mobility. A restriction of movement at the level of the ankle joint (between calcaneus and talus) just above the heel bone is even to be expected (see risk factors).
No neurological signs present in an Achilles tendinopathy
Muscle and tendon complaints
The calf muscle may be excessively tense and the Achilles tendon may feel swollen and painful. The muscle and especially the tendon can be both pressure and strain sensitive. During or after exercising or straining the tendon, we see pain and stiffness symptoms.
Other muscles around the ankle and knee may be more tense as a protective response.
Sometimes there is also bursa inflammation. Both the bursa between the Achilles tendon and the heel bone and the bursa between the skin and the Achilles tendon can be inflamed along with the Achilles tendon.
Role of physical therapy and your physical therapist
Physical therapy will be important to match the load to the load capacity of the tendon. The first goal is to reduce the pain symptoms and then increase the load capacity of the tendon so that the symptoms are no longer present. Finally, the goal is to strengthen the Achilles tendon to avoid a relapse and incorporate prevention of tendinopathy.
Physical therapy examination
At Magnus, we start with the Get It Right First Time principle. Through a comprehensive physical therapy examination, we want to make sure we start the correct treatment path from day 1.
Your physical therapist starts with an interview to get a clear picture of the complaints. The history of the complaints is checked and how the symptoms present themselves. This information is important to verify it is a tendinopathy. Getting a good picture of the strain and symptoms are crucial to estimating the load capacity and stage of tissue damage. Furthermore, this information helps to perform a correct physical therapy clinical examination and confirm the hypothesis about the symptoms.
The clinical examination starts with the inspection of the patient in stance. Evaluation of the position of the feet, anatomical abnormalities (e.g. hallux valgus) and the patient's general posture are identified and reported. The active and passive examination is then performed. This includes evaluation of the mobility of the ankle and neighboring joints (knee, hip and sometimes the lumbar spine).
In addition, the strength, length and tension of the calf muscles and pain sensitivity of the Achilles tendon will be examined. Through specific palpation of the Achilles tendon, an assessment can be made of the tension, sensitivity to pressure, swelling, ... . In case of severe complaints, it makes sense to also perform a Simmonds-Thompsen test to rule out an Achilles tendon rupture. This can also be done for other muscles around the knee and ankle to see if they are more tense. Further testing is done to see if there may also be inflammation of the bursa.
Neurological examination can be performed if there was an indication for this in the questionnaire. These neurological signs are then more likely to indicate the presence of a second pathology.
When the tendinopathy is not yet too severe (read: relatively little pain), the physical therapist will examine how the patient moves during painful (sports) activities.
In principle, medical imaging is not required to confirm the diagnosis. Moreover, nothing changes for the treatment. Only when the examination indicates a complete tear does it make sense to undergo an MRI or Ultrasound to confirm the diagnosis.
Treatment by your physical therapist
Treatment starts with adjusting the load on the Achilles tendon. The load is reduced to relieve the tendon but not stopped. Staying active is important because this is precisely how the tendon can become stronger. The goal is to find the right relationship between load and load capacity as quickly as possible tailored to the patient. Especially explosive jumping and sprinting forms should be avoided because these peak forces create a high tendon load.
Reducing the tension on the calf muscles (soleus and gastrocnemius) will relieve the tendon and reduce pain. The physical therapist uses various treatment techniques to relax the muscle such as deep massage, dry needling and trigger point therapy.
When muscles are too short, which disrupts normal joint mobility, techniques to increase muscle length can be applied. Simply stretching when there is no shortage is not helpful. With reduced mobility in the ankle joint, the physical therapist performs mobilizations at the joint level to restore normal mobility. Mobilizations are small movements of the bone that allow the joint to return to normal function. This means that the bones move correctly relative to each other when bending or stretching.
As mentioned earlier, proper exercise therapy plays a central role in pain management. In addition, there is a focus on progressive loading of the tendon. In the first phase, only isometric exercise therapy may be pain-free. Then, as soon as possible, it is built up to eccentric training of the tendon with attention to correct execution. The exercise forms in which the tendon is loaded are also progressive:
The goal is to strengthen the tendon so that the activities before the complaints can be resumed pain-free. We also want the patient to know what he/she can do preventively to stay pain free.
In the short term, we focus on pain relief and improving ankle and foot mobility. By adjusting the load and relieving the muscle, the pain will quickly diminish. The goal here, however, is to remain active and, together with the physical therapist, map out the load and load capacity as well as possible. Recording your sports activities with an activity tracker such as a smartwatch can be helpful here.
As the load and load capacity are balanced, the exercise therapy can be intensified as well as the (sports) activities. Progressively building strength, endurance and coordination within the load capacity is crucial. In principle, the pain should decrease through time until it is completely gone. Subsequently, it is advisable to integrate preventive therapy for some time. It is advised to make the tendon so strong that a sudden (unexpected) increase in load does not necessarily lead to relapse. The patient should also know this for when he/she plans to suddenly increase (sports) activities in the future.
Sometimes corticosteroids are prescribed. It is important to note that this can relieve pain in the early stages and make it easier to start exercise therapy. In the long term, however, there are negative effects of using CS because the tendon structure is affected. Therefore, it is best not to use it (Irby et al., 2020).
Extracorporeal shockwave therapy (ECST) can also be used to possibly improve pain control (Stania et al., 2019). This is only effective in a small group of patients. It is important to note that there is a wide range of ECST (different wavelengths) and it must be set correctly to possibly be effective. In practice, we rather see that the structure of the exercise therapy is not correct so that the patient exactly does not make any progress. Good cooperation between patient and physical therapist, as well as a quality exercise plan, should in principle be sufficient. It is better to build up slowly than too quickly. If a patient comes to Magnus for a 2nd opinion, we often see that this is the cause of the ongoing problem.
In addition, there are a few techniques that can be employed such as topical glyceryl trinitrate and hyaluronic acid injection (Challoumas et al., 2021). These may be useful in the first phase of rehabilitation to generate a "window of opportunity" when regular rehabilitation is laborious (pain remains the same despite adaptation load and start-up of a correct treatment strategy). However, the evidence remains very low and has not yet been demonstrated for the Achilles tendon.
Surgery is in principle not necessary when it is not a complete tear.