Page 367 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

342 CHAPTER 1

VetBooks.ir INFERIOR CHECK LIGAMENT due to overextension of the DIP joint. It is com-
(ACCESSORY LIGAMENT OF THE DEEP
monly encountered in general purpose or retired
DIGITAL FLEXOR TENDON) DESMITIS
ponies and in older animals used for jumping. It may
also occur in young animals, in association with a
Definition/overview sudden-onset DIP joint flexural deformity (inability
This condition is similar to SDF tendinopathy and to lower the heels onto the ground). This is likely to
is characterised by partial to complete tear of the be secondary to pain and muscle contraction in the
inferior check ligament. It affects mostly pleasure, DDFT/AL-DDFT apparatus. Adhesions between
draught and sports horses and ponies, particularly the dorsolateral aspect of the DDFT and the
those over 10 years of age, but all types of horses may AL-DDFT may result from focal trauma, chronic
be affected. It is most common in the forelimb, but SDF tendinopathy or AL-DDFT desmitis. It is pos-
also occurs in the hindlimb (tarsal check ligament). sible that these adhesions predispose to AL-DDFT
tears or lead to recurrence, hence negatively influ-
Aetiology/pathophysiology encing prognosis.
The AL-DDFT forms a ligamentous band, aris-
ing from the palmar carpal or short plantar tarsal Clinical presentation
ligament proximally, at the level of the carpometa- Acute lameness occurs during, and immediately after,
carpal/tarsometatarsal joint capsule, and joining exercise. There is usually severe, diffuse swelling
the DDFT, blending with the latter’s fibres at the in the proximal and middle metacarpal (metatarsal)
junction of the middle and distal thirds of the meta- area, most obvious on the lateral aspect (Fig. 1.671).
carpus/metatarsus. Its role is presumably to bypass The condition may evolve chronically, with recur-
the DDF muscles when the limb is loaded, in order rent bouts of swelling and lameness. Chronic cases
to decrease energy requirements. The aetiology of show marked thickening of the tendon area. In some
spontaneous tears is unclear, but probably involves cases, a flexural deformity of the DIP joint occurs
gradual, age-related degeneration, predisposing to with persistent lameness and limb postural changes
an acute tear. Repeated, cyclic strain is most likely (Fig. 1.672).

1.671 1.672

Fig. 1.671 Diffuse swelling over the
palmar aspect of the metacarpus due to
subacute inferior check ligament injury.

Fig. 1.672 Chronic inferior check
ligament injury associated with severe,
acquired loss of extension of the DIP joint
(‘flexural deformity’).