320 Canine Sports Medicine and Rehabilitation
Currently, there are no data on the incidence,
treatment, or outcome after fracture of the ulnar
or carpal bones. Diagnosis can be difficult due
to small fragmentation of the bones.
Medial and lateral collateral ligament sprains
can occur due to acute trauma, repetitive trauma
with breakdown over time, or conformational
abnormalities leading to chronic strain of the
ligaments. Much as with carpal hyperextension
injuries, the degree of damage (grade 1, 2, or 3)
will dictate the appropriate course of treatment.
FCU strains may be the result of acute tendini
tis, implying an inflammatory condition from
acute traumatic tendon fiber tearing, or the
result of chronic tendinosis, leading to a tendi
nopathy. Most chronic FCU tendinopathies are
the result of overuse and a dysfunctional repair
response. In these conditions, breakdown of the
collagen matrix is involved and there is no
inflammation within the tendon (Dirks &
Warden, 2011). High‐level or prolonged periods
of tensile stress due to repetitive, intense activi
ties can lead to collagen breakdown. Because of
the lack of inflammatory activity in these condi
tions, most patients are unresponsive to rest and
NSAIDs. Although it seems counterintuitive,
initiating an inflammatory response is neces
sary to activate the healing process.
Diagnosis
Diagnosing carpal injures can be challenging,
especially for mild sprain and strain conditions.
The diagnosis is based on a comprehensive
orthopedic evaluation and various imaging
techniques. Lameness can range from a chronic,
intermittent, low‐grade lameness to an acute,
non‐weight‐bearing lameness. It is important to
evaluate patients at both the walk and the trot if
they are weight bearing on the limb. Attention
should be given to the carpus during the stance
phase of the gait to evaluate for evidence of car
pal hyperextension (Figure 12.25). Palpation may
reveal soft tissue swelling, discomfort, crepitus,
decreased range of motion, or instability when
stressed (flexion, extension, varus or valgus). In
cases of a mild (grade 1–2) strain of the ligamen
tous structures, instability may not be present. As
part of a complete orthopedic evaluation palpa
tion of the contralateral limb should be used as a
reference in determining abnormal motion.
Imaging choices and techniques will vary
depending on the injury. Radiographic changes
are often nonspecific and may reveal soft tissue
swelling within the region of injury. In chronic
cases of medial or lateral collateral strains,
enthesiophyte formation may be noted
(Langley‐Hobbs et al., 2007). For possible liga
mentous instability or luxation/subluxation,
stress radiographs can be beneficial and may
reveal evidence of medial or lateral joint space
widening, carpal hyperextension (Figure
12.26A), or dorsal subluxation (Figure 12.26B).
Attention should be paid to the carpal bones for
any evidence of fractures or fragmentation.
Unfortunately, carpal bone fractures can be dif
ficult to diagnose on standard radiographic
views. Additional views such as oblique or sky
line may help in diagnosing a carpal fracture.
The authors recommend always taking radio
graphs of the contralateral nonaffected carpal
joint for comparison. In cases of suspected car
pal fractures or other osseous pathological
changes, a CT scan can be performed (Gnudi
et al., 2003). In cases of ligamentous or other soft
tissue injury an MRI or ultrasound are often
required for a definitive diagnosis. For soft tis
sue lesions such as an FCU strain, medial or lat
eral collateral ligament injury, or other
ligamentous injuries the authors (SC and DD)
prefer to begin with diagnostic musculoskeletal
ultrasound. Ultrasound allows for minimally
invasive direct visualization of the supporting
structures and evaluation of the architecture of
the tissues for objective grading of the injury
such as a grade 1, 2, or 3 strain (Figure 12.27).
Furthermore, ultrasound allows for easy follow‐
up in response to treatment. For cases where
ultrasound is nondiagnostic or more informa
tion needs to be obtained an MRI may be rec
ommended (Figure 12.28).Treatment
Treatment options for carpal injuries will vary
based on which tissue is damaged. For exam
ple, with carpal bone fractures, if there is
enough bony purchase for an implant, then lag
screw or Kirschner wire fixation can be
attempted after absolute anatomic reconstruc
tion since these fractures are intra‐articular
(Kapatkin et al., 2012). If the fragment is small, it