(See also Overview of Foot and Ankle Disorders Overview of Foot and Ankle Disorders Most foot problems result from anatomic disorders or abnormal function of articular or extra-articular structures (see figure Bones of the foot). Less commonly, foot problems reflect a systemic... read more .)
Posterior Achilles tendon bursitis occurs mainly in young women. Wearing high-heeled shoes is a risk factor. Another risk factor is a bony prominence (Haglund deformity) on the calcaneus. This deformity predisposes to bursa formation if repeatedly irritated by the shoe counter.
Symptoms and Signs
Symptoms and signs of posterior Achilles tendon bursitis develop at the top edge of the posterior shoe counter. Early symptoms may be limited to redness, pain, and warmth. Later, superficial skin erosion may occur. After months or longer, a fluctuant, tender, cystic nodule 1- to 3-cm in diameter develops. It is red or skin-colored. In chronic cases, the bursa becomes fibrotic and calcified.
Diagnosis
Symptoms and a small, tender, and skin-colored or red nodule
The presence of the small, tender, and skin-colored or red nodule in a patient with symptoms consistent with posterior Achilles tendon bursitis is diagnostic. Rarely, an Achilles tendon xanthoma develops at the top edge of the posterior shoe counter but tends to be pink and asymptomatic. Achilles tendon enthesopathy causes pain mainly at the tendon’s insertion but may also cause pain at the top edge of the posterior shoe counter. Enthesopathy is differentiated by the absence of a soft-tissue lesion.
Treatment
Modification of footwear
Properly fitting shoes with low heels are essential for people with posterior Achilles tendon bursitis. A foam rubber or felt heel pad may be needed to lift the heel high enough so that the bursa does not contact the shoe counter. Protective gel wraps, padding around the bursa, or the wearing of a backless shoe until inflammation subsides is indicated. Foot orthotics may enhance rear foot stability and help reduce irritating motion on the posterior calcaneus while walking.
Warm or cool compresses, nonsteroidal anti-inflammatory drugs (NSAIDs), and intrabursal injection of a local anesthetic/corticosteroid solution offer temporary relief; the Achilles tendon itself must not be injected (see Considerations for using corticosteroid injections Considerations for Using Corticosteroid Injections 
). Surgical removal of a portion of the underlying bone may rarely be necessary to reduce soft-tissue impingement.
