What is Tendon Ossification

A tendon is a strong fibrous tissue that connects the skeletal muscle to the bone. Ossification and calcification of tendon is seldom recognized clinically, and is otherwise known as heterotrophic calcification (that is bone formation outside its normal location). The new bone formed is in the form of spicules, plates and irregular masses, and when connected with bone they are called exostoses. The causes, symptoms of tendon ossification, its diagnosis and treatment are discussed in this article.

Causes of tendon ossification

The major cause of a tendon ossification is ossification following a surgical intervention or trauma. The other causes include vascular insufficiency, dystrophic calcification, osteomyelitis, chronic infections such as syphilis, Reiter`s syndrome, renal diseases and crystal arthropathies.

Symptoms of tendon ossification

Tendon ossification is most often a symptomless condition and is detected only upon dissection. But in advanced conditions it presents itself as pain on physical activity or increased difficulty on ambulation. In general, tendon ossification is usually symptomless and requires no treatment, but, in some cases, the ossification ruptures and fractures, causing severe pain, and may need surgical intervention.

Diagnosis of tendon ossification

Tendon ossification can be diagnosed by examination and radiographic imaging. It is best viewed using ultrasonography, single photon emission, computed tomography and transmission computed tomography. Physical examination reveals the presence of a painful bony hard mass and soft tissue swelling in the site of the tendon. There is no erythema or warmth in the site of the pain.

Radiography reveals multiple opaque lesions, caused as a result of a micro or a macro trauma. The etiopathogenesis is that there is tissue hypoxia. The poor blood supply causes the tendon to transform into a fibro cartilage, where chondrocytes mediate the deposition of calcium, and a bony mass is formed with organized trabecular bone. Tendon ossification of Achilles is thus classified into the following types, based on their radiographic appearance: Type 1 lesions are lesions on the superior pole of calcareous; Type 2 lesions are radio opacities located at the insertion of the Achilles tendon; Type 3 lesions are radio opacities that occur at least 12 cm from the insertion; Type 3A is partially ossified; and type 3B are totally ossified lesions.


Tendon ossification is usually asymptomatic, and does not usually require any treatment. But if it is symptomatic, or if the ossification ruptures leading to its fracture, the treatment required is a surgical intervention. The treatment usually involves tendon resection and reconstruction and placing of grafts.To avoid total resection,  fixation can be done to the osseous fragments, with a figure of eight wire.