Chronic Achilles tendinopathy is one of the most common tendon disorders, both for athletes and for people who are not necessarily involved in sports. However, the causes and mechanisms are not yet fully understood, so the treatment often poses a real challenge for doctors and recovery specialists. Although many patients recover with a conservative treatment based on gradual loads, some cases are resistant and show no improvement over time. A group of researchers recently examined whether the plantaris tendon could be behind these cases; if so, it would imply an incorrect diagnosis which would in turn affect recovery, as a different treatment is required.

Lorenzo Masci, consultant and sports doctor, presented this new evidence in the conference held last year and will also assist to the 11th Barça Sports Medicine Conference organised by Barça Innovation Hub. He also published a summary of the findings in the journal apunts. Medicina de l´sport.

The Plantaris Tendon, an Important Suspect

The tendon corresponding to the plantaris muscle basically runs through the internal part of the entire calf, passing down the side of the Achilles tendon and ending where it is inserted into the calcaneus bone, although the exact path varies from person to person. Although the muscle is not particularly functional in humans, it seems that it can lead to problems. In recent years, more and more cases of resistant Achilles tendinopathies have been observed as a result of the plantaris tendon and the Achilles tendon being excessively close. At times, the tendons were even attached to each other and were surrounded by a swollen tissue, with a matrix of disorganised internal connective tissue. “We believe that there is a subgroup of patients who are experiencing a plantaris interference. We still don’t know its incidence rate, but we are seeing an increasing number of patients for whom traditional rehabilitation is not effective”, says Masci.

It is still not known in detail how the plantaris damages the Achilles, but it is suspected that when the plantaris thickens, it ends up compressing and thickening the Achilles, which can sometimes cause them to adhere to each other. It is also believed that certain anatomical variants in its path increase this risk.

Repercussions for Diagnosis and Treatment

The plantaris involvement may be considered when there is mid-portion and inner Achilles tendinopathy that is resistant to treatment. An ultrasound may reveal a thickened tendon with increased blood flow. Other more advanced imaging techniques, such as Ultrasound Tissue Characterisation, can reveal a disorganised collagen matrix in the area of the Achilles related to the plantaris.

In regard to the treatment, standard rehabilitation consists of “a progressive high-load program, usually a series of calf raises”, explains Masci. “However, our hypothesis is that plantaris-related Achilles tendinopathy is more difficult to manage. Studies on corpses have shown increased pressure between these tendons at the extremes of plantarflexion and dorsiflexion, so we recommend limiting these exercises in order to avoid overloading the tendons.” A more effective exercise could be to focus on the average range of ankle positions.

Another treatment option could be surgery, in order to remove the plantaris tendon. The few studies that have been carried out so far look promising, but Masci remains cautious: “We still need clinical trials to prove our hypothesis”, he concludes.

The Barça Innovation Hub team

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