When we discuss Achilles tendinopathies (including tendinitis, tendinosis, tenosynovitis, etc.), we are very likely talking about mid-portion Achilles tendinopathies. This is a fairly common condition that most injury therapists will see on a regular basis.
But don’t forget, there is a far less common form of the condition, known as insertional Achilles tendinopathy (IAT).
Due to its rarity, how much do we actually know about this condition? How are the mechanism of injury and symptoms different to those of mid-portion injuries? Should we be treating these cases differently? Let’s find out!
Mechanism of Injury
Insertional Achilles tendinopathy usually develops gradually over a period of days or weeks. There is no sudden moment of injury; no bang or pop. This is the same with mid-portion tendinopathies.
The cause of insertional cases is often also very much the same as with mid-portion cases. This is usually a sudden increase or change in activity. In those who play sports, it might be a match-heavy period.
In runners, distance may have been increased too quickly or hill runs suddenly introduced. For the sedentary cases, they may have had a change in job or routine that has made them more active.
The difference in mechanism between the two forms really is the biomechanical cause of the irritation. In the case of mid-portion Achilles tendinopathies, the cause is thought to be excess loading which the tendon could not withstand.
In the case of IAT, the cause is thought to be compression or shearing of the tendon at the attachment to the calcaneus. When the ankle moves into the end range of weight bearing dorsiflexion, the deep layers of the Achilles tendon are compressed against the calcaneus.
This compression happening again and again causes irritation of the tendon, loss of parallel tendon structure, fiber integrity, and capillary proliferation, resulting in overall tendon degeneration.
Symptoms
The symptoms of both forms of Achilles tendinopathy are very similar. Both cases usually present with:
- A gradual onset of pain
- Pain in the back of the heel
- Pain that is worst in the mornings or after periods of rest
- Pain on active or resisted plantarflexion
- Redness and swelling
The main difference between the two is the location of the pain and swelling. In insertional cases, the pain is lower, within 2 cm of the calcaneus. In mid-portion cases, the average point of most pain is 3-7 cm proximal to the calcaneus.
Mid-portion cases usually display some redness or swelling around this area and in chronic cases a clearly thickened tendon. Insertional cases demonstrate a lower area of swelling and redness and in more chronic cases a lump at the insertion.
Differential diagnosis
Whilst it could be very easy to assume that all cases of pain at the back of the heel are insertional Achilles tendinopathy, there are several other conditions which must be considered either in conjunction with, or as an alternative to an IAT diagnosis.
Retrocalcaneal bursitis
This is the most common form of heel bursitis, which affects the bursa that sits between the calcaneus and the anterior fibers of the Achilles tendon. The symptoms are very similar to those of IAT, so it may be difficult to tell the two conditions apart without imaging. They may also often occur together.
Haglund’s deformity
This is an additional growth of bone on the posterolateral corner of the calcaneus. The condition is often associated with, and in many cases is the cause of, retrocalcaneal bursitis. It presents as pain and swelling around the Achilles insertion.
Severs disease
Also known as calcaneal apophysitis, this condition is similar to Osgood-Schlatter disease, which occurs at the knee. It occurs in young athletes (usually 7-15 years) who take part in running or jumping events where the repetitive microtrauma from traction on the Achilles causes damage to the apophyseal growth plate.
Pain is usually absent in the mornings and gets worse with activity. Squeezing the medial and lateral aspects of the calcaneus will elicit pain.
Treatment of IAT
So, should we be treating insertional Achilles tendinopathy differently to mid-portion? The answer here is yes! To understand why, and how, we must look back to the mechanism of the injury.
Mid-portion Achilles tendinopathy occurs due to a failure of the tendon to withstand the load placed upon the tendon. This explains the most favored treatment regimen of eccentric strengthening and all those heel drop exercises!
However, for IAT, we have learned that loaded end range dorsiflexion results in further compression of the Achilles insertion. Therefore, the heel drop regimen and weight-bearing calf stretch exercises should be avoided. Instead, the recommendations are as follows:
- Ease symptoms using modalities for pain relief, alongside the use of a heel lift in shoes. This will result in reduced dorsiflexion at the ankle in day-to-day activities and less compression of the tendon insertion.
- Once pain starts to subside, strengthening can begin with isometric exercises initially, in a slightly plantarflexed position, again to reduce compression at the insertion.
- Once able, begin strengthening through calf raises whilst maintaining a slightly plantarflexed position throughout (e.g., place a small book under the heel).
- Phase out the heel lift for day-to-day activities.
- Start to increase calf raise range of motion — remove book.
If conservative treatment fails, there are other options. Corticosteroid injection is generally not recommended for the Achilles tendon due to concerns over the increased risk of tendon rupture. It can, however, be used successfully for the treatment of retrocalcaneal bursitis.
Extracorporeal shockwave therapy has been used successfully for the treatment of IAT although there is currently no evidence-based standardized protocol and some patients may find the treatment itself too painful to continue with.
Open debridement and decompression have been successfully used for IAT once conservative treatment has failed. But as with all surgery, there are risks and it cannot be recommended until all nonoperative measures have been attempted.
