Page 156 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.4 The forelimb 131

VetBooks.ir 1.229 1.230

Fig. 1.229 Postoperative lateromedial radiograph Fig. 1.230 A case of distal proximal phalangeal
of a case of pastern osteoarthritis treated by pastern osseous cyst-like lesions with secondary severe
arthrodesis. osteoarthritis of the proximal interphalangeal joint.

Prognosis Clinical presentation
Prognosis for horses undergoing chemical arthrod- OCLLs may present as low-grade insidious lameness
esis is less than in the small tarsal joints and approxi- or, occasionally, as acute lameness. Clinical signs
mately 60% of horses return to previous or higher related to the pastern may be scant.
levels of work after 8–12 months. Horses undergo-
ing surgical arthrodesis using transarticular screws Differential diagnosis
+/- plates have a good prognosis for return to func- Pastern OA; pastern subluxation; synovial sepsis;
tion. In the hindlimb, success rates of 85% of horses foot/fetlock lameness.
performing their intended use have been reported,
although rates tend to be lower in the forelimb. Diagnosis
OCD lesions may be detected on radiography or
OSTEOCHONDROSIS MRI following localisation by diagnostic anaesthe-
sia. Secondary joint disease (OA) may be associated
Definition/overview with chronic lesions.
Osteochondrosis (OCD) of the pastern joint is
uncommon. Manifestations of OCD in the pastern Management
include osseous cyst-like lesions (OCLLs) and osteo- OCLLs can be managed conservatively with intra-
chondral fragmentation. articular medication and/or palliative treatment.
Surgical debridement, usually via an extra- articular
Aetiology/pathophysiology approach, and the use of bone grafts or other bone
Palmar/plantar osteochondral fragmentation is con- replacement have been used to resolve the cyst in
sidered a traumatic incident and was discussed in some cases. PIP joint arthrodesis has also been used
the section on fractures of the proximal and middle in management of OCLLs.
phalanges. Osteochondral fragments on the dorso-
proximal margin of P2 have been described but are Prognosis
of unknown clinical significance. OCLLs in the pas- Outcome of horses with PIP joint OCLLs is gen-
tern occur in distal P1 or, less commonly, proximal erally guarded and concurrent joint disease signifi-
P2 (Fig. 1.230). cantly reduces the prognosis.