Equine-Orthopédique : A case of avulsion of the tuber calcis in a horse

Sporting Mare, warmblood 6 years. Imported since 1 month from belgium.

Owner concerns: counter performance, stumbling

Clinical exam:
- marked waistage of the gluteal muscles
- deformation at the level of the calcaneus and left tarsus swollen
- no lameness visible in straight line
- flexion LH positive 2/5

Radiography: lateral projection left tarsus

Can you establish a diagnostic? Are other views required?
A large, well defined bony element is seen superimposed onto the proximal aspect of teh calcaneus. The calcaneus shows an irregular outline.

A skyline and oblique views of the tarsus are necessary to precise the origin and the localisation of the fragment.


A large bony fragment, with a trabecular structure is visible on the dorsolateral aspect of the calcaneus. A cortex and a medulla are clearly discernable, This structure implies that the fragment is of bony origin and not a soft tissue mineralization. The surface of the calcaneus in regard is irregular.

Old avulsion fracture of the lateral surface of the calcaneus
An ultrasound is recommended to visualize lesion at the level of the SDFT, and of the flexor retinaculum.

Pronostic: reserved

L'aspect d'os trabéculaire avec cortex et médulla du fragment confirme la provenance osseuse du fragment. If this was not the case, the differential list could be:

- osteoma of the soft tissues
- calcinosis circumscripta
- old calcified hematoma
- dystrophic mineralization

In general, calcinosis circumscripta (tumoral calcinosis) looks like punctate deposit of mineralized tissues, corresponding to calcium precipitate. A localized soft tissue swelling is often associated. A common place is the lateral aspect of the femorotibial joint.

Osteomas are benign tumors based onbony surfaces and growing by intramambranous ossification. The bovine and equines are predisposed particularly at the level of the head. They are slow progressing tumors.

Literature: JAVMA, Vol 221, No. 5, September 1, 2002