Page 682 - Adams and Stashak's Lameness in Horses, 7th Edition

648 Chapter 5

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Figure 5.55. Radiographs of a subluxated left shoulder in a
miniature horse that was lame at the walk. The joint had significant
radiographic signs of OA. Source: Courtesy of Dr. Gary Baxter.

have responded favorably to intrasynovial anesthesia are
candidates for arthroscopy. Localized cartilage damage
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is debrided down to healthy subchondral bone, and oste-
ochondral fragments are removed if they are loose.
There are reports of performing scapulohumeral
arthrodesis in miniature horses to reduce morbidity in
those with severe shoulder dysfunction. 6,89 A narrow
DCP was placed across the cranial surface of the scap-
ula, and the humerus with screws placed in lag fashion Figure 5.56. Cranial‐caudal radiograph of the same miniature
across the joint through the plate. This procedure horse in Figure 5.55. The humerus and scapula were positioned
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improved the horses’ lameness by several grades, more laterally than normal. Source: Courtesy of Dr. Gary Baxter.
improving morbidity.
Ponies appear to be at a greater risk for this condi-
tion. 8,23,40,60,101 The head of the humerus can displace in
Prognosis several directions, including cranial, 63,101 craniolateral,
The prognosis appears favorable for horses without lateral, craniomedial, and medial (Figure 5.56). 23,40,50
radiographic apparent lesions that respond favorably to When the humerus becomes luxated, it displaces proxi-
intra‐articular anesthesia and are treated conservatively mad due to the contraction of the muscles surrounding
with rest and intra‐articular therapy. Those with obvious the SH joint, and the direction of the luxation appears to
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radiographic evidence of OA generally do not respond well. depend on the direction of the inciting injury.
The prognosis for horses treated by arthroscopy Of the cases presented in which the direction of the
appears good for subtle cartilage lesion. In the case of luxation was documented, lateral luxation with proximal
SH joint OA due to shoulder dysplasia in ponies, the displacement was most common. 40,60,63 Because the equine
prognosis does not appear as favorable. In a report of 20 SH joint is stabilized by a ball‐and‐socket articulation, the
ponies, 6 were euthanized for continuing severe lame- tendons from surrounding muscles, and the glenohumeral
ness, and the other 14 remained lame. In two other ligaments within the joint capsule, it is not surprising that
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case reports, ponies remained lame despite concurrent luxation of the joint results in considerable damage to
conservative treatments. 53,76 these structures. 23,40 In one report arthroscopic examina-
tion following closed reduction of a luxated SH joint of
2‐weeks’ duration revealed bony and soft tissue debris, a
LUXATION OF THE SCAPULOHUMERAL cartilage defect, and a tear in the joint capsule. 63
(SHOULDER) JOINT

Luxation or subluxation of the SH joint is uncommon Etiology
in horses. In a survey of 128 cases of suspected shoulder Luxation of the SH joint generally occurs following
lameness in horses, only 2 cases had shoulder luxation. excessive (forceful) trauma to the shoulder region such
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