Page 370 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.8 Soft-tissue injuries 345

VetBooks.ir recurrent cases. The latter respond well to surgical PARATENDONITIS
treatment. If flexural deformity is present, the prog-
Definition/overview
nosis for return to work is generally poor.
Tendons are sheathed in a connective tissue layer
DEEP DIGITAL FLEXOR TENDINOPATHY outside areas where a synovial sheath is present.
(OUTSIDE SHEATHED AREAS) This layer, termed paratenon, adheres to the ten-
don parenchyma and is made of non-aligned, loose
Overview connective tissue. It contains a network of blood
Injury to the DDFT in the metacarpal or metatar- vessels that supply the tendon (Figs. 1.678, 1.679).
sal region outside of the sheathed portions (i.e. tarsal These are organised in a coiled manner to allow for
or carpal sheaths, DFT sheath and podotrochlear longitudinal movement of the tendon in relation to
[‘navicular’] bursa) has been described but appears surrounding tissues without being overstretched.
to be extremely rare. It is most often associated This layer may be injured in several ways, in associa-
with extension of AL-DDFT lesions distally. It has, tion with tendinopathy or not, leading to thicken-
however, been observed in young Thoroughbreds ing, adhesions and decreased vascular supply to the
in training, with findings similar to those of SDF tendon. Common terminology for this condition
tendinopathy. The cause is unclear. The lesions have includes bandage bow or peritendinopathy. It has
been treated conservatively with apparent success, been addressed in the human literature as a signifi-
although there is no objective study evaluating this cant component of tendon disease but has received
condition in the literature. little interest in veterinary medicine. Paratendonitis

1.678

Fig. 1.678 Schematic organisation of the external 1.679
blood supply to tendon. The paratenon is an external
layer of loose but dense, fibrous connective tissue.
It contains a dense network of coiled arteries that
provide arterial supply to the endotenon surrounding
the fibre fascicles. The tendon also receives blood
supply from arteries originating from its muscle head.
Fig. 1.679 Transverse histological section of tendon
(H&E stain) showing collagen fibres and tenocyte
nuclei in the lower half of the image, and the overlying
paratenon. The latter contains more loosely arranged
cells and matrix as well as large blood vessels. (After
E. Cauvin, PhD Thesis, University of London, 2000)