DISCUSSION
In small animals, fractures of the scapular body are categorized by
articular involvement as well as stability including intra-articular,
unstable extra-articular, and stable extra-articular (Cook et al, 1997).
This categorization scheme guides the need for stabilization (surgical
or coaptation) as well as prognosis. Surgical intervention is
recommended for intra-articular as well as unstable extra-articular
fractures of the scapula. The filly in this report fits into the
category of a stable extra-articular fracture in which conservative
management is an appropriate treatment option. The comfort level of the
horse in this case was also a large determinant of management, as the
horse was weight-bearing. Potential complications for conservative
management of this fracture include mal- or non-union, propagation or
displacement of the fracture, development of angular limb deformities or
laminitis in the support limb or flexural limb deformity in the affected
limb, secondary suprascapular neuropathy, and persistence of lameness.
There are several reports of surgical repair of fractures of the
supraglenoid tubercle in horses, only one case report describing the
repair of a fracture of the scapular body was identified (Auer and
Furst, 2017; Kidd et al, 2007). Kidd et al reported a longitudinal
scapular fracture of the infraspinous fossa in a 2-year-old horse. The
horse was reported to be sound by ten months (Kidd et al, 2007). Repair
of these fractures in a foal could result in an increase in morbidity
due to the application of internal fixators to thin, compact bone. The
ability to reduce the fracture line would be limited and the goal of
repair would be to provide stability, which is inherently provided by
the large muscle mass surrounding this region. With lack of glenoid
cavity involvement, the risk of degenerative joint disease was
negligible. In the authors’ opinions, the treatment of choice for stable
extra-articular fractures of the scapula is conservative management.
The prognosis for return to full function for such fractures with
conservative management in small animal medicine is said to be excellent
(Peck, 2012; Cook et al, 1997). The prognosis for equine athletes cannot
be determined based on the extrapolation of small animal cases, as the
definition of full function for a pet animal and an adult horse differ.
Recovery of three cases with longitudinal body fractures has been
described in the equine veterinary literature. As previously mentioned,
a single case report by Kidd et al describes one horse returning to
soundness after surgical repair. Dyson reports one horse returning to
previous use while another was retired. Based on reported cases, of both
small animals and horses, it is suggested that scapular fractures
without articular involvement carry a better prognosis for future
soundness than fractures with articular involvement (Peck, 2012; Cook et
al, 1997; Dyson, 1985; Kidd et al, 2007).
With suspected fractures of the equine proximal forelimb, ultrasound has
been described as a valuable diagnostic tool (Davidson and Martin,
2004). Ultrasound has the limitation of only being able to highlight the
lateral aspect of the scapula and centers of ossification or normal
roughening of the bony surface can be confused with a fracture line.
While the exact configuration of a fracture cannot be determined by
two-dimensional imaging alone, radiography was able to highlight the
displacement in the cranial-caudal plane, while ultrasonography was
performed as an adjunctive diagnostic tool to evaluate displacement of
the fracture in the frontal plane and the concurrent soft tissue
damage. Nuclear scintigraphy has been reported to have little value in
the diagnosis of lameness in foals due to a diffuse increase in
radiopharmaceutical uptake of the normal physes (Hunt, 2011).
The gold standard for the determination of the exact configuration of
fractures is a computed tomographic (CT) examination. Prohibiting
factors of such examination include patient size as well as equipment
access, owner funds, and the associated risks of general anesthesia.
With standard radiographic views of the shoulder, the diagnosis would
have not been reached in this case. In cases where the standard
radiographic views are non-rewarding and there is an indication of
proximal limb lameness such as crepitus, reduced cranial phase of the
stride, dropped elbow, or pain on palpation, an additional skyline view
of the body of the scapula may be indicated. The skyline radiographic
view described in this report was sufficient for the diagnosis and
development of a treatment plan. To the knowledge of the authors, this
radiographic projection has not yet been described in the equine
literature. This radiograph was captured with a low-output portable
generator making the acquisition of this image achievable to field
practitioners. Superimposition of the opposing limb and thoracic
structures makes the diagnosis of a dorsal scapular fracture difficult
with traditional radiographic views. In neonatal foals, a lateral view
of the cranial thorax may allow for visualization of the entire scapula,
however, the described oblique view (D45ºL-VLO) provides the advantage
of anatomic isolation.
When the radiographic examination was repeated after six months with a
low-output portable generator, the fracture was no longer present. As
the horse aged and significantly increased in size, the radiographic
image quality decreased, especially in the distal aspect of the scapula.
Better radiographic images could likely be obtained with a high-output
radiographic generator and a higher exposure. Based on the findings in
this case report, the authors recommend using the described radiographic
projection in conjunction with ultrasound if there is a suspicion of a
fracture of the scapular body. In addition, extra-articular stable
fractures, with none or minimal displacement carry on a good prognosis
with conservative management.