How to treat deep digital flexor tendon injuries more accurately and effectively

Tendinopathies of the deep digital flexor tendon are a very common cause of lameness in sport horses. Our athletic horse population is affected by the same types of injuries that have been widely described in different studies and treatment of these lesions strongly depends on the accurate localization of the site of injury or injuries in the same tendon at different levels and the characterization of these (extensive; mild, moderate, severe,etc). However, we have seen a more specific discipline induced presentation of injury in our Chilean Rodeo horses.

To describe DDFT lesion location in a proximodistal direction, four levels were established. Level 1 was proximal to the collateral sesamoidean ligaments and to the proximal recess of the navicular bursa in the sagittal plane. Level 2 corresponded to the level of the collateral sesamoidean ligaments and proximal recess of the navi- cular bursa. Level 3 was between the proximal and distal extents of the distal sesamoid bone. Level 4 extended from the distal border of the distal sesamoid bone distally.

The anatomy of the digit and association of the DDFT with other structures provides an explanation for the presence of multiple sites of injections. Within the hoof capsule the DDFT is moulded to the palmar surface of the navicular bone and separated from it by the podotrochlear or navicular bursa. The distal recess of the bursa separates the DDFT and the distal sesmoidean impar ligament (DSIL) (Dyson 2003). The DDFT has a terminal fan like expansion containing cartilage that occupies the entire space between the medial and lateral palmar processes of the distal phalanx and inserts on the facies flexoria and semilunar crest of the distal phalanx. The dorsal portion of the DDFT joins with the DSIL immediately before insertion on the facies flexoria of the distal phalanx (Dyson 2003) and understanding the normal anatomy is essential for the detection of abnormalities, injuries and potential sites of local therapy.

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