In previous articles, we discussed an assortment of Achilles tendon disorders from a physical therapy perspective including Achilles tendinitis, Achilles bursitis, and Achilles tendinopathy, the latter of which is also known as Achilles tendinosis and will be the focus on this article. All of these Achilles tendon disorders can present with a variety of signs and symptoms.

The differences between a sign and symptom is that a sign is something an observer will see related to the injury or condition, whereas a symptoms is something the patient will feel or experience due to the injury or condition.

This article will focus on a classic sign of Achilles tendinopathy: a thickened Achilles tendon. While this sign may be accompanied by symptoms, such as Achilles tendon pain or tightness, it doesn’t necessarily have to be accompanied by any symptoms, which can be more common in the early stages of Achilles tendinopathy.

What causes a thickened Achilles tendon?

Given a thickened Achilles tendon is a common sign associated with Achilles tendinopathy (also known as Achilles tendinosis), one could also ask “How do you get Achilles tendinopathy?”.

Achilles tendinopathy with an associated thickened Achilles tendon can result from overuse of the calf muscles, also known as the triceps surae, whereby the volume of load exceeds the Achilles tendon’s capacity to withstand that load in a healthy manner, which can ultimately result in symptoms within the tendon itself or on the heel bone where it attaches.

The Achilles tendon is similar to other tissue in the body in that it has the capacity to remodel itself to withstand the stresses typically places on it.

However, when there is an excessive breakdown of the collagen fibers that make up the tendon and not enough time for recovery in between, which can happen with repetitive stress, a person can be more prone to developing a thickened Achilles tendon.

One way to picture the Achilles tendon is like a sleeve (tendon) of thin cables (collagen fibers) that need to be organized properly to withstand tensile forces.

If that sleeve of cables is constantly stressed without appropriate recovery and repair, they can become disorganized like a bowl of noodles instead of a strand of cables, which can lead to palpable and/or visual thickening of the Achilles tendon, and eventually, Achilles tendon pain.

If this is left unaddressed, the tendon may become less functional, and over time, other symptoms like Achilles tendon pain and stiffness can develop and potentially lead to other Achilles tendon injuries.

The tendon or heel bone may be painful to the touch, or may be painful with activity that places lots of stress on the tendon or heel bone, such as running and jumping.

Additionally, other risk factors for Achilles tendinopathy are listed in the image below, all of which can affect the morphology of the tendon and/or its ability to withstand the loads placed on it.

Tight Achilles Tendon With Running

One of the most common activities that can result in a thickened Achilles tendon is running. Running involves a high volume of workload for the calf muscle complex, and by association, the Achilles tendon. As such, Achilles tendon injuries can be common in long distance runners.

One common symptom reported by runners is tightness in the Achilles tendon. While this is extremely common and doesn’t necessarily mean you are developing Achilles tendinopathy, it’s a good indicator that you should probably check in with your physical therapist for a consult to get on top of minimizing the risk of Achilles tendon injuries.

In a recent study conducted by Tillander et al (2019), a group of middle-aged long distance runners had their Achilles tendons examined by ultrasound imaging to see if there was any connection between Achilles tendon thickness and symptoms that they were experiencing.

In this case, the main symptom they were considering was pain, but this is typically associated with tightness as well. The authors found that symptomatic Achilles tendons were significantly thicker than non-symptomatic tendons, and this thickness was usually found about 3cm (1.2 inches) up from the tendon’s insertion on the back of the heel bone.

The authors do point out that previous studies looking at Achilles tendon properties in runners, such as thickness and stiffness, were enhanced relative to non-runners. This can be a good thing if it means the tendon is more capable of withstanding that load.

However, as we eluded to previously, if there is too much stress on the Achilles tendon, then pain and dysfunction can result.

So what does this mean from a clinical perspective?

In reality, Achilles tendon thickness should be viewed as a continuum, meaning it’s not always a bad thing, but can be a bad thing if it progresses too much and increases the risk of Achilles tendon injuries.

For runners who are experiencing tightness in their Achilles tendon, especially if it’s asymmetrical, it’s always a good idea to check in with a physical therapist to see if there are any ways to avoid dealing with pain and dysfunction in the tendon in the future.

Thickened Achilles Tendon in Soccer Players

A study conducted by Jhingan et al (2011) investigated the relationship between Achilles tendon thickness and the development of Achilles tendinopathy in elite professional soccer players.

Similar to the running study above, they investigated the incidence of Achilles tendinopathy symptoms in these athletes with and without abnormalities detected on ultrasound imaging.

The authors found that baseline Achilles tendon thickness, specifically in the mid-portion of the tendon (i.e. not directly on the heel bone), was higher in the soccer players who eventually went on to experience symptoms in their Achilles tendons over the next year.

As a result, the authors concluded that a thicker baseline mid-tendon thickness was a risk factor for the development of Achilles tendinopathy in elite soccer players.

We should note that Achilles tendinopathy doesn’t exclusively occur in the mid-portion of the tendon, but can also occur at its insertion site on the back of the heel bone, which would be termed insertional Achilles tendinopathy. In this case, people may complain of heel pain with or without pain, stiffness, or thickening in the mid-portion of the tendon.

Can Achilles tendinopathy lead to Achilles tendon rupture?

Achilles tendon ruptures can be devastating injuries in that they can severely impact your day-to-day function while you recover. Many treatment programs are now opting for non-surgical approaches to Achilles tendon ruptures, but nevertheless, the rehab process is still quite conservative and takes a long time (e.g. 8+ months).

One study conducted by Yasui et al (2017) found that 4% of people in the United States with diagnosed went on to sustain a rupture.

While this may seem like a low number, it’s high enough to suggest that Achilles tendinopathy may increase the risk of Achilles tendon ruptures, which should be a motivating factor to properly treating Achilles tendinopathy.

Another article written by Maffulli et al (2020) in the journal Foot and Ankle Surgery described the controversy linking Achilles tendinopathy to Achilles tendon rupture; however, when summarizing the available evidence, they perceived a high association of tendinopathy and Achilles tendon rupture.

In this case, they did acknowledge that this association may be detected given that many studies investigate painful Achilles tendinopathy, suggesting that those participates had fairly advanced forms of tendinopathy, and as such, may have been more susceptible to Achilles tendon ruptures.

How do you treat a thickened Achilles tendon?

In reality, we don’t really treat a thickened Achilles tendon, but rather, the underlying processes of Achilles tendinopathy that may be promoting the thickening.

This will likely include exercise-based therapy to strengthen the calf muscles, such as a heel drop program that is strategically progressed over time, which will help build capacity to withstand the stress on the Achilles tendon.

A heel drop program is basically a progressive strengthening program for the calf muscles, which aims to increase the resiliency of the Achilles tendon.

Calf raises are a huge part of this, and over time, the strength regime will progress in terms of amount of resistance/load on the calf muscles and Achilles tendon, and may include eccentric strengthening, whereby the tendon is being lengthened while the calf muscles are contracting.

While heel drop programs include calf muscle strengthening regimes that are fairly straight forward, it’s still worth having this program optimized by a physical therapist to ensure safe and effective treatment.

For example, a heel drop program for insertional Achilles tendinopathy with high degree of heel pain may look a bit different than your classic mid-portion Achilles tendinopathy, and these considerations can be guided by a physical therapist.

Other tools like shockwave therapy, dry needling, and electrical stimulation can help assist in recovery of Achilles tendinopathy, but aren’t typically stand-alone treatments. A podiatrist may also be able to advise on footwear or orthotics to help reduce Achilles tendon pain.

What else can contribute to a thickened Achilles tendon?

According to some other studies, the presence of Type 2 diabetes may contribute to the development of a thickened Achilles tendon (Akturk et al, 2007).

Additionally, in people who have coronary heart disease, it was shown that a thickened Achilles tendon was associated with higher disease severity relative to those with a normal tendon thickness (Hashimoto et al, 2019).

Summary

A thickened Achilles tendon is a classic sign of Achilles tendinopathy, a common condition in repetitive activities that place a lot of stress on the Achilles tenon, such as jumping activities and long distance running.

While a thicker Achilles tendon doesn’t always mean you have Achilles tendinopathy, it can warrant a consult with a physical therapist for prevention and treatment of Achilles tendon pain and tightness.

Treatment for Achilles tendinopathy will focus primarily on strengthening the calf muscles and loading the tendon, but there are other tools available in most physical therapy clinics that can further assist in recovery.

Additionally, other conditions like diabetes and coronary artery disease can be associated with a thickened Achilles tendon, which is yet another reason to have a healthcare professional take a look if you’re at all concerned.

References

Akturk, M. Ü. J. D. E., Ozdemir, A., Maral, I. Ş. I. L., Yetkin, I., & Arslan, M. (2007). Evaluation of Achilles tendon thickening in type 2 diabetes mellitus. Experimental and clinical endocrinology & diabetes, 115(02), 92-96.

Hashimoto, T., Minami, Y., Kakizaki, R., Nemoto, T., Fujiyoshi, K., Meguro, K., & Ako, J. (2019). Achilles tendon thickening is associated with disease severity and plaque vulnerability in patients with coronary artery disease. Journal of Clinical Lipidology, 13(1), 194-200.

Jhingan, S., Perry, M., O’Driscoll, G., Lewin, C., Teatino, R., Malliaras, P., & Morrissey, D. (2011). Thicker Achilles tendons are a risk factor to develop Achilles tendinopathy in elite professional soccer players. Muscles, ligaments and tendons journal, 1(2), 51.

Maffulli, N., Longo, U. G., Kadakia, A., & Spiezia, F. (2020). Achilles tendinopathy. Foot and Ankle Surgery, 26(3), 240-249.

Tillander, B., Gauffin, H., Lyth, J., Knutsson, A., & Timpka, T. (2019). Symptomatic achilles tendons are thicker than asymptomatic tendons on ultrasound examination in recreational long-distance runners. Sports, 7(12), 245.

Yasui, Y., Tonogai, I., Rosenbaum, A. J., Shimozono, Y., Kawano, H., & Kennedy, J. G. (2017). The risk of Achilles tendon rupture in the patients with Achilles tendinopathy: healthcare database analysis in the United States. BioMed research international, 2017.

Disclaimer:

The content here is designed for information & education purposes only and is not intended for medical advice.