Page 398 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.8 Soft-tissue injuries 373

VetBooks.ir 1.738 1.739

Fig. 1.738 Longitudinal sonogram over the Fig. 1.739 Transverse sonogram over the
sustentaculum tali. There is a large, irregular defect at plantaromedial aspect of the distal tarsus, which
the surface of the latter (yellow arrows). The overlying had sustained a kick to this area. Note the bony
LDF tendon is hypoechogenic and has lost its normal fragmentation of the medial rim of the sustentaculum
fibre pattern (arrowhead). There is a tremendous tali and associated soft tissue fibrous reaction. (Photo
amount of synovial thickening in this chronically courtesy Graham Munroe)
inflamed tarsal tendon sheath (red arrow).

Prognosis to slip in the opposite direction during hock flex-
The prognosis is good to fair in acute cases, except in ion. The condition is usually unilateral, but bilateral
the presence of severe tendon tears. In chronic cases injuries have been described.
the prognosis remains fair with tenoscopic surgery,
although extensive tendon lesions are usually asso- Aetiology/pathophysiology
ciated with a guarded prognosis. Infectious tenosy- Probably traumatic either by direct injury or during
novitis yields a good prognosis if aggressive lavage excessive exercise. Horses with a straight hock and/
can be implemented early on (within 12 hours), but or fetlock overextension are predisposed. The luxa-
the chances for a full recovery decrease rapidly with tion may be complete or partial (subluxation) and
time and chronicity. Concurrent fragmentation most commonly occurs laterally. It may be intermit-
of the sustentaculum tali carries a good prognosis, tent or permanent.
unless a significant proportion of the gliding surface
for the tendon has been damaged. Clinical presentation
Rupture of the branch is acute, causing sudden-
LUXATION OF THE SUPERFICIAL FLEXOR onset lameness. Typically, the horse is severely dis-
TENDON FROM THE TUBER CALCIS tressed as the tendon slips on and off the calcaneus.
In most cases the luxation is initially intermittent,
Definition/overview as the tendon comes off the tuber calcis during hock
The SDFT normally attaches to the tuber calcis of flexion and returns to its normal position during
the calcaneus via two abaxial fibrous branches; these limb extension. There is associated distension of
prevent the SDFT slipping sideways but allow it to the calcaneal bursa. The tendon eventually remains
glide over the bone. Rupture of the medial or, less in a permanently dislocated position in many cases
commonly, the lateral branch will cause the tendon (Fig. 1.740).