Page 665 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Proximal Limb 631

internal fixation is required because conservative manage-
ment fails. Conservative management usually results in
VetBooks.ir Attempts to repair the collateral ligaments in complete
continued instability and resultant osteoarthritis.
42
luxations have been attempted. Prosthetic collateral liga-
71
ments have been made by placing screws in the medial and
lateral epicondyles of the distal humerus and the proximal
tuberosities of the radius near the attachment of the col-
lateral ligaments and wrapping surgical wire around them
in a figure‐8 pattern to emulate the ligament. 71
Luxations in conjunction with an ulna fracture have
been reported with no attempt to repair the collateral
ligaments. The fracture was repaired with a broad DCP
placed on the caudal surface of the ulna. Stability was
attributed to the interdigitation of the three bones of the
elbow joint. With any repair attempt, significant dis-
82
traction is necessary to aid the replacement of the luxa-
tion; in one case a small (1 cm) piece of the anconeal
process was removed to assist in reduction. Removal
71
of the anconeal process should not affect prognosis. 2,39

Prognosis
The prognosis for subluxation of the elbow appears
to be guarded to unfavorable to return to performance,
depending on the degree of injury to the medial collat-
eral ligament. Generally, a partial tear injury is expected
76
to have a better prognosis, and some of these horses may
be able to return to light work.
The prognosis for complete luxation is generally con-
sidered guarded 71,73,76 ; however, there are at least two
Figure 5.38. Luxation of the elbow joint with the humerus reports of repairs, and the horses were considered sound
displaced medially. No fracture was present. Source: Reprinted with 6 and 14 months after surgery; the former horse had a
permission from Rubio‐Martinez et al. 71 concomitant ulna fracture. 17,82

signs for a subluxation. Palpation of the medial aspect Subchondral Defects and Subchondral Cystic Lesions
of the joint and manipulation elicit a painful response, (SCLs) of the Elbow
and limb instability may be noticeable. Signs associated
with partial rupture of the medial collateral ligament Subchondral defects and subchondral cystic lesions
may be less obvious because there is less inherent insta- (SCLs) of the elbow joint are uncommon, although they
bility. Swelling may still be noticeable on the medial have been observed in a wide variety of horse breeds of
aspect of the joint. Joint effusion is usually noticeable all ages. 8,36,95 SCLs typically communicate with the joint,
laterally along with a grade 2–3 of 5 lameness. Flexion and they most commonly occur on the medial side,
or abduction exacerbates the lameness. 76 involving either the proximal medial radius or distal
A complete luxation usually causes severe swelling medial condyle of the humerus (Figure 5.39). Although
36
and discomfort, with horses unable to bear weight nor uncommon, SCLs can occur bilaterally.
extend their limb. This will not resolve until correct
alignment and stabilization is established. 76 Etiology

Proposed causes for subchondral defects and SCLs
Diagnosis include osteochondrosis at a weight‐bearing location in
A definitive diagnosis is made with radiographic the joint and trauma. Trauma is perceived to occur by a
examination. Subluxation may require stressed views, concussive event, causing damage to the cartilage and
and chronic cases may reveal evidence of osteoarthritis subchondral bone plate, and the resultant pressure and
and an enthesiopathy of the medial collateral ligament. presence of synovial fluid developing a cystic lesion.
Stressed views are performed by manipulating the limb
to exacerbate the subluxation, in this case by stabilizing Clinical Signs
the humerus and applying pressure to the radius in a
medial or lateral direction. Horses often present with a history of an acute onset
of lameness that may wax and wane with use. 8,36
Palpation of the caudal aspect of the elbow joint capsule
Treatment
may reveal fluid distension and some thickening. Flexion
Closed reduction and conservative management has and extension of the elbow region often elicits a painful
been achieved in select cases, 17,42 but more commonly, response, and a flexion test usually exacerbates the