Page 371 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

346 CHAPTER 1

VetBooks.ir (or paratenonitis) is used when the there is obvious supply or because of the inflammation and tissue
resorption induced by platelet degranulation and
involvement of the paratenon.
The paratenon may become significantly thick-
ened as a result of tendon disease and it may lead WBC invasion, the lesion often extends second-
arily into the underlying tendon or ligament tissue.
to adhesion formation. If adhesions are allowed to In some rare cases, intravascular thrombosis can
become fibrous, they may predispose to recurrence lead to focal necrosis of the tendons. Entrapment of
of the tendon strain or cause persistent pain and/or the neurovascular structures around the damaged
exercise intolerance. The author has also encoun- paratenon may be a significant component of persis-
tered a number of paratenon lesions unassociated tent or recurrent pain.
with tendinopathy.
Clinical presentation
Aetiology/pathophysiology Paratendonitis can occur in any unsheathed portion
The cause may be inflammation and/or haemor- of exposed tendons. The most common sites include
rhage in the contiguous tendon parenchyma. It is the digital flexor tendons, AL-DDFT, SL, the digi-
significant, therefore, in diffuse lesions or when tal extensor tendons and the common calcaneal
lesions extend to the peripheral layers of the ten- tendon. Swelling is often marked with oedema,
don or ligament. Paratendonitis may be particularly pain on palpation and lameness. The appearance is
significant in SL, SDFT and AL-DDFT injuries. often indistinguishable from tendinopathy/ desmitis
Direct trauma to the paratenon may be associ- (Fig. 1.681). In the plantar aspect of the hock,
ated with kicks, interference injuries, hitting fixed paratendonitis is a common cause of ‘curb’ defor-
objects or pressure from tight or slipped bandages mity (Fig. 1.682). Lameness is variable but may be
(Fig. 1.680). Haemorrhage occurs in and around the surprisingly severe, especially when inflammation
paratenon. Either through damage to the vascular extends to the neurovascular bundles (palmar or

1.680 1.681

Fig. 1.680 Self-incurred traumatic
injury to the palmar aspect of the
metacarpus. Note the associated swelling
(‘bowed leg’), due to contusion, oedema
and haemorrhage, in and around the
paratenon.

Fig. 1.681 Diffuse deformity of the
plantar aspect of the proximal metatarsus,
giving a bow-legged appearance (between
arrows). This was due to paratendonitis.
without tendon parenchymal involvement;
however, the clinical appearance is
indistinguishable from tendinopathy.