Page 180 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.4 The forelimb 155

VetBooks.ir CARPUS

CARPAL OSTEOARTHRITIS
along the dorsal margins of the carpal bone may be
palpable.
Definition/overview
Degenerative joint disease of one or more carpal Differential diagnosis
joints. Osteochondral fragmentation; carpal fracture; soft-
tissue injury; subluxation.
Aetiology/pathophysiology
Carpal OA occurs due to joint insult as a sequela Diagnosis
to joint trauma (e.g. sprain/subluxation), synovial Localisation of the lameness through intra- articular
sepsis, intra-articular fracture, soft-tissue injury analgesia of the carpal joint(s). Standard radio-
(e.g. medial palmar intercarpal ligament [MPICL] graphic projections will demonstrate radiographic
injury), OCD or osteochondral fragmentation. signs of OA (Fig. 1.289).
Osteochondral fragmentation can be a cause as well
as a result of OA. Poor distal limb conformation Management
(e.g. ‘back-at-the-knee’ or ‘bench-knee’) will con- Management of carpal OA is mainly palliative
tribute to abnormal forces on loading through the through intra-articular medication and/or NSAIDs,
carpus. Certain breeds (e.g. Arabs) have a predisposi- although stem cells have been used in some
tion to OA of the carpometacarpal joint (Fig. 1.287). cases, providing temporary improvement. Removal
of osteochondral fragments may reduce irrita-
Clinical presentation tion in the joint. Often, marked cartilage loss and
Horses present with often moderate levels of lame- poor subchondral bone is present arthroscopically.
ness with joint effusion/thickening of the joint cap- Debridement of loose cartilage flaps and forage,
sule (Fig. 1.288). Horses will be positive to carpal as well as joint lavage, may help in the short term.
flexion and may resent passive flexion. Irregularity Surgical ankyloses of the carpometacarpal joint

1.287 1.288

Fig. 1.287 Dorsolateral/
palmaromedial oblique
radiograph of a horse
with osteoarthritis of the
carpometacarpal joint. Note
the collapse of the joint
medially and the surrounding
increased subchondral bone
sclerosis. (Photo courtesy
Graham Munroe)

Fig. 1.288 Photo showing
swelling over the dorsal aspect
of both carpi, which was related
to palpable new bone formation
as well as joint effusion of the
carpal joints.