Page 166 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.4 The forelimb 141

VetBooks.ir 1.254 1.255

Figs. 1.254, 1.255
MRI clearly demonstrates
the pathology of palmar/
plantar osteochondral
disease affecting the
lateral condyle on the
dorsoplantar view (1.254)
and the plantar condyle
distribution on the
lateromedial view (1.255).

CHRONIC PROLIFERATIVE SYNOVITIS Diagnosis
Radiography may show a crescent-shaped radio-
Definition/overview lucency on the dorsal aspect of the distal third
Chronic proliferative synovitis or villonodular syno- metacarpus due to cortical lysis. Dystrophic miner-
vitis of the fetlock refers to the presence of a soft- alisation may also be present. Contrast arthrography
tissue mass in the dorsal aspect of the joint, more may provide further detail. Ultrasound is sensitive
commonly affecting the forelimb(s) of the horse. in demonstrating thickening of the synovial pad
(>10 mm) and associated joint changes at the dorsal
Aetiology/pathophysiology aspect. Radiography should also be performed to
Chronic repetitive trauma to the dorsal aspect of examine for evidence of OA, especially in the palmar
the fetlock from hyperextension leads to hyperplasia aspect of the joint (Fig. 1.256).
of the bilobed synovial pad over the sagittal ridge.
Osteoclastic resorption leads to supracondylar lysis of Management
the underlying bone. Conditions such as the presence Medical therapy and changes to the exercise regime
of a dorsoproximal P1 fragment may also result in may help in some cases. Intra-articular hyaluranon
chronic inflammation of the dorsal aspect of the joint. and corticosteroids, with rest initially, followed by
alteration in training pattern, are often helpful.
Clinical presentation Surgical excision by sharp debridement or laser dis-
A palpable thickening over the dorsal aspect of the section has been performed arthroscopically and
affected fetlock joint is found on clinical examina- removal of associated fragmentation can be per-
tion, with or without joint effusion. Reduction in formed concurrently (Fig. 1.257).
range of motion of the joint can also be appreciated
in some cases and lameness will usually worsen fol- Prognosis
lowing exercise and distal limb flexion. The prognosis is variable but generally guarded to
poor and depends on the presence of degenerative
Differential diagnosis joint disease. Resolution of the problem can be tem-
Fetlock OA; fetlock joint trauma; synovial sepsis; injury porarily achieved, but recurrence is common unless
or infection of the common digital extensor bursa. an underlying cause can be found.