The Achilles tendon, also known as the tendo Achilles, tendo calcaneus or calcaneal tendon, is the longest tendon of the body, formed by the union of the lower aspect of the calf muscles (gastrocnemius, soleus and the variably present plantaris muscle).
The tendon inserts by way of a broad insertion on the calcaneus (heel bone) of the hindfoot. During development, the Achilles tendon is continuous with the broad flat tendon of the foot known as the plantar fascia (figure 1).
As for any tendon, degeneration due to wear and tear may occur, known as tendinosis (incorrectly frequently referred to as tendinitis). Achilles tendinosis results in pain during activities such as running and may be seen in combination with degeneration of the plantar fascia (plantar fasciitis, or “heel spurs”) and strains of the calf muscles .
Most cases of tendinosis resolve with conservative therapy, which consists of exercises, eccentric strengthening, heel inserts and activity modification.
Initially, imaging with either an ultrasound (figure 2) or an MRI is performed in order to determine the degree and extent of the tendinosis, as well as the presence of any tears and surrounding inflammation (paratenonitis, retrocalcaneal and/or retroAchilles bursitis).
Achilles tendinosis typically involves the mid portion of the tendon (figure 4) and left untreated, may result in dramatic painful rupture (figure 5) with sudden loss of function, warranting surgery.
Less frequently, the tendinosis may involve the insertion of the Achilles onto the calcaneus (known as enthesopathy) and may be seen in conjunction with certain arthritic diseases, as well as increasing age (figure 6). In this instance, changes within the bone may be seen, such as fluid (oedema) and prominence of the calcaneus, known as Haglund’s deformity.
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- Pavlov H, Heneghan MA, Hersh A, Goldman AB, Vigorita V. The Haglund syndrome: initial and differential diagnosis. Radiology. 1982 Jul;144(1):83-8.
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