Table 1.

Terminology for Achilles tendon related disorders, including the anatomic location, symptoms, clinical findings histopathology

Term	Anatomic location	Symptoms	Clinical findings	Histopathology
Mid-portion Achilles tendinopathy	2–7 cm from the insertion onto the calcaneus	A combination of pain, swelling and impaired performance	Diffuse or localized swelling	Includes, but is not limited to, the histopathological diagnosis of tendinosis: implies histopathological diagnosis of tendon degeneration without clinical or histological signs of intratendinous inflammation, not necessarily symptomatic
Paratendinopathy
Acute	Around the mid-portion Achilles tendon	Edema and hyperaemia	Palpable crepitations, swelling	Edema and hyperaemia of paratenon, with infiltration of inflammatory cells, possibly with production of a fibrinous exudate that fills the space between tendon sheath and tendon
Chronic	Around the mid-portion Achilles tendon	Exercise-induced pain	Crepitations and swelling less pronounced	Paratenon thickened as a result of fibrinous exudate, prominent and widespread proliferation of (myo)fibroblasts, formation of new connective tissue and adhesions between tendon, paratenon, and crural fascia
Insertional Achilles tendinopathy	Insertion of Achilles tendon onto calcaneus, most often with formation of bone spurs and calcifications in tendon proper at insertion site	Pain, stiffness, sometimes a (solid) swelling	Painful tendon insertion at the mid-portion of the posterior aspect of the calcaneus, swelling may be visible and a bony spur may be palpable	Ossification of enthesial fibrocartilage, and sometimes small tendon tears occurring at tendon-bone junction
Retrocalcaneal bursitis	Bursa in the recess between the anterior inferior side of the Achilles tendon and the posterosuperior aspect of the calcaneus (retrocalcaneal recess)	Painful swelling superior to calcaneus	Painful soft tissue swelling, medial and lateral to the Achilles tendon at the level of the posterosuperior calcaneus	Fibro-cartilaginous bursal walls show degeneration and/or calcification, with hypertrophy of the synovial infoldings and accumulation of fluid in the bursa. Alternatively, the bursa may be primarily involved by inflammatory or infectious bursitis due to an inflammatory arthropathy
Superficial calcaneal bursitis	Bursa located between calcaneal prominence or the Achilles tendon and the skin	Visible, painful, solid swelling postero-lateral calcaneus (often associated with shoes with rigid posterior portion)	Visible, painful, solid swelling and discoloration of skin. Most often located at postero-lateral calcaneus; sometimes posterior or posteromedial	An acquired adventitious bursa, developing in response to friction. When inflamed, lined by hypertrophic synovial tissue and fluid.

For radiographic findings see Table 2