Mid substance (non-insertional) Achilles tendinopathy: A guide for patients

The Achilles tendon

The Achilles tendon is formed from two muscles; the gastrocnemius, which begins above your knee and the soleus, which begins beneath the knee. The two muscles then move down the leg and form the Achilles tendon.

The fibres of the Achilles tendon, unlike some other tendons, are spiral. This allows for the tendon to increase in length when put under stress and for energy/spring to be released while you are walking.

Also, unlike other tendons, the Achilles tendon has a very thin layer of tissue covering it. This tissue supplies the blood vessels to the tendon. About two centimetres above the insertion of the tendon into the heel bone, there is a reduction in the blood supply to the tendon. This area then extends about four centimetres upwards and is the most likely place for pathology to develop (Achilles tendinopathy).

Causes of Achilles tendinopathy

The causes of Achilles tendinopathy are unclear, however various theories include:

• Excessive tendon loading during training
• Function of the Achilles tendon
• Age
• Gender
• Body weight
• Ankle instability or unstable ankle
• Very high arched foot
• Certain medications
• Excessive heel motion, which can lead to whipping of the tendon
• Recent discoveries have shown certain gene expressions can have an effect on tendon cellular activity.

Often, in Achilles tendinopathy the paratenon (a thin membrane covering the tendon) can be affected as well or in isolation.

When the Achilles tendon becomes problematic, it is often associated with swelling and pain. The pain is not due to inflammation but due to chemical mediators being released from the degenerative tendon which then sensitises the surrounding nerves.

Investigations

Investigations include ultrasound and MRI scans. An X-ray might be done to rule out any bony abnormality.

Treatment

Conservative management

There are favourable long-term outcomes which combine:

• Rest
• Anti-inflammatory drugs
• Eccentric stretching
• Physiotherapy - ultrasound, extracorporeal shockwave therapy and massage
• Insoles (orthotics)
• Injections.

Orthotics aim to correct the biomechanics of the foot and ankle. They can have up to a 75 per cent success rate.

When returning to activities, altering your exercise programme, for example reducing your exercise time or speed, has been shown to help. This allows the tendon to rehabilitate itself and prevent it happening again.

Deep friction massage also helps with healing and should be accompanied by stretching exercises.

Eccentric stretching exercises

Eccentric stretching is when a muscle - in this case the gastrocnemius and the soleus - is contracting and an external force is trying to lengthen it. Eccentric stretching exercises are beneficial.

These need to be carried out twice a day. It should feel hard and you may experience some discomfort or pain during the first two weeks. However, if you experience disabling pain you should stop the exercises.

The stretching exercise is firstly carried out with the knee straight (picture below) and then with the knee slightly bent; this allows for both the calf muscles to be independently exercised.

To stretch the muscle, your forefoot is placed on the step with the rest of the foot hanging over the edge of the step. You then drop your heel down beneath the level of the step until it can go no further. The opposite leg does not rest on the step and is only used to bring you back up to the start position. It is important not to use the bad leg to get you back to the start position.

Once you are able to carry out the exercises without any pain and discomfort, you need to increase the amount of weight carried during stretching. For this, you will need to get a backpack. Load it with heavy books, bricks or weights. Again, the exercises will become uncomfortable. Do not overload the backpack so that the discomfort or pain prevents you from carrying out the exercises.

The exercises need to be carried out with the knee straight and then bent:

Knee straight

• Twice a day
• Seven days-a-week
• One set (once)
• 100 repetitions.

Knee bent

• Twice a day
• Seven days-a-week
• One set (once)
• 100 repetitions.

These exercises need to be carried out for three months; after this a certain amount of stretching is advisable.

Other stretching exercises include those that can be done against a wall. These should not be exchanged for the eccentric exercises but done in addition to, as long as they do not cause too much discomfort.

Calf stretches

Theses need to be carried out twice a day. The leg that is behind you is the leg you are stretching.

• Place your hands on a wall with your arms outstretched.
• Your hand should be in line with your shoulders.
• Put one leg in front of the other.
• Your feet should be as wide apart as your pelvis and hips – you do not need to be pigeon toed or have your feet too far apart.
• Your feet should be at a right angle (90 degrees) to the wall and you should be facing the wall.
• Foot position is very important and at the beginning you may require help in positioning your feet.
• With your back leg behind you, keep your foot on the ground and your knee extended (locked). The leg that is behind you is the leg that you are stretching.
• Once you are in position, bend the front knee and move your hips and upper body, as a whole, towards the wall. It is important not to bend your back towards the wall as this will not put a stretch on the leg.
• You will feel a stretch down the back of the leg. When you can feel it hold the stretch and do not bounce backwards and forwards. Hold the stretch for one minute.
• After one minute swap legs, reposition yourself and repeat the stretch on the other leg.
• Stretch each leg three times, for one minute, alternating between right and left legs.
• Stretching should be carried out at least twice a day, preferably three times.

Injectables

A high-volume image guided injection can be carried out (under ultrasound guidance). The injection comprises water, local anaesthetic and steroid. The injection separates the paratenon from the tendon; the separation of the paratenon from the tendon reduces the amount of new blood vessels being formed in the tendon. This formation contributes to the condition’s pathology. In a short-term study, the overall thickness of the tendon reduced and there was an improvement in pain levels.

Surgical management

Twenty four to forty five per cent of patients who fail to respond to conservative care need surgical management.

Surgery will only be considered after six months of exhaustive conservative treatment.

Surgery aims

The aim is to reduce the pain and improve your functional ability.

There are different types of surgical approaches that include:

• releasing any adhesions that may have formed between the tendon and the paratenon
• excision of the degenerative/nodular areas from the tendon itself. Rarely, a tendon transfer is required.

By carrying out these procedures the degenerated tendon and painful stimuli are removed. The blood supply to the tendon to initiate healing is also increased.

In some cases, the tendon degeneration can be extensive and may require the transfer of a tendon from one area of the foot to the Achilles tendon.

If surgery is necessary, this will be discussed in greater detail with your podiatric surgeon. It is important to realise that the recovery timeline can vary depending on the procedures carried undertaken.