Introduction
Historical perspective
Mid-portion Achilles tendinopathy
Pathology around the Achilles tendon insertion
Proposed terminology for Achilles tendon related disorders
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. |
Term/Imaging | Plain radiography | Ultrasound | CT | MRI |
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Mid-portion Achilles tendinopathy | Deviation of soft tissue contours is usually present. In rare cases calcifications can be found | Tendon larger than normal in both cross-sectional area and antero-posterior diameter. Hypoechoic areas within the tendon, disruption of fibrillar pattern, increase in tendon vascularity (Echo-Doppler) mainly in ventral peritendinous area | In case (massive) calcification are seen on plain radiography. CT imaging can be helpful in pre-operative planning, showing the exact size and location of the calcifications. | Fat- saturated T1 or T2 images: fusiform expansion,central enhancement consistent with intratendinous neovascularization |
Paratendinopathy | ||||
Acute | – | A normal Achilles tendon with circumferential hypoechogenic halo | – | Peripheral enhancement on fat-saturated T1 or on T2 images |
Chronic | A thickened hypoechoic paratenon with poorly defined borders may show as a sign of peritendinous adhesions; increase in tendon vascularity (Echo-Doppler) mainly in ventral peritendinous area | |||
Insertional Achilles tendinopathy | May show ossification or a bone spur at the tendon’s insertion; possibly deviation of soft tissue contours | Calcaneal bony abnormalities | Bone formation at insertion. CT scan is indicated mainly for pre-operative planning. It shows the exact location and size of the calcifications and spurs | Bone formation and/or on STIR (short tau inversion recovery) hyperintense signal at tendon insertion |
Retrocalcaneal bursitis | A postero-superior calcaneal prominence can be identified; radio-opacity of the retrocalcaneal recess; possibly deviation of soft tissue contours | Fluid in the retrocalcaneal area/bursa (hyperechoic) | – | Hyperintense signal in retrocalcaneal recess on T2 weighed images |
Superficial calcaneal bursitis | Possibly deviation of soft tissue contours | Fluid between skin and Achilles tendon | – | Hyperintense signal between Achilles tendon and subcutaneous tissue on T2 weighed images |