348 Canine Sports Medicine and Rehabilitation
into a healing phase that allows the therapist to
complete soft tissue work, including cross‐fric-
tion massage and stretching, thus modifying
adaptively shortened tissues. As the tissues
remodel, gentle strengthening, motor timing
(the sequencing of a type of muscle contrac-
tion), and motor control of exercises (the graded
intensity of a muscle contraction) are initiated
to return the muscle to pain‐free functional con-
tractions. Completion of the healing phase of
treatment includes eccentric strengthening
exercises to return the muscle to full strength
(Verrall et al., 2011) (Table 13.3).
Ligament and joint capsule injuries
Ligaments are comprised of nonextensible paral-
lel collagenous fibers with minimal vascular sup-
ply. Their purpose is to stabilize joints, preventing
excessive motion. When the external forces on a
ligament exceed the physiological load, fiber fail-
ure occurs in the form of fiber disruption. Grade I
ligament injuries are microtears that will present
as pain without joint instability. Grade II tears
produce severe pain and minor to moderate joint
instability. Grade III tears are severely painful at
onset with decreasing pain following the injury
and gross joint instability (Nordin & Frankel,
1989). The joint instability of grade II and III tears
allows for increased displacement of the joint sur-
faces causing further ligament fiber disruption,
excessive pressure to the joint capsule, increased
force on tendons, and abnormally high stresses on
articular cartilage. In the canine model this has
been shown to modify forces through the joint
structures and cause deterioration of articular car-
tilage (Marshall & Olsson, 1971).
Multiple factors affect the biomechanical
properties of ligaments including aging, preg-
nancy and the postpartum period, mobiliza-
tion, and immobilization. These factors are
considered as they impact the course of treat-
ment and anticipated physiological outcomes.
Aging causes a decrease in tensile strength of
the ligament due to declining collagen content,
placing older patients at higher risk for liga-
ment injuries. Overall body condition and fit-
ness should meet or exceed the physical
activities of patients. This is particularly true in
canine athletes and older patients that may be
completing activities that exceed the abilities
of their muscles to protect the joints, placing
the stabilizing ligaments at risk for injury.
Pregnancy and the postpartum period see a
release of relaxin, which increases the distensi-
bility of ligaments (Goldsmith et al., 1994). In
the dog, mobilization and exercise has been
shown to increase the tensile strength of liga-
ments (Montgomery, 1989) while, in the pri-
mate model, immobilization for 8 weeks was
found to decrease the tensile strength of liga-
ments by up to 39%. The same study showed
that a reconditioning program of 12 months
was required to reach pre‐immobilization ten-
sile strength (Noyes, 1977). Biomechanical
properties of the ligament and factors affecting
ligament integrity are considered when creat-
ing a treatment plan, including fiber alignment
for optimal force resistance and decreased
vascularity. Treatment plans first consider the
grade of ligament rupture. Conservative non-
surgical approach of ligament sprains greater
than grade I require external stabilization of the
joint with bracing such as a hobble‐type support
for the glenohumeral joint with medial shoulder
instability. The course of treatment includes
edema management with modalities and man-
ual therapy in the acute phases followed by a
graded return of strength in the muscles sup-
porting the hypermobile joint, such as subscap-
ularis and superficial pectoral strengthening for
medial shoulder instability (Table 13.3).Intra‐articular injuriesArticular cartilage, by virtue of its viscoelastic
characteristics, distributes loads through the joint
and allows for smooth arthrokinematics. In canine
subjects, exercise groups (running for 1 hour at
15% incline for 5 days per week for 15 weeks)
showed an increase in stifle cartilage thickness
compared with crated controls (Kiviranta et al.,
1988). Lubrication is diminished with injury to the
articular cartilage, as stress and strain forces are
not distributed evenly during loading. Canine
studies have shown that immobilization‐induced
atrophy of cartilage does not improve after 50
weeks of activity resumption (Kiviranta et al.,
1994; Haapala et al., 1999). Impairment of force
distribution causes compensatory changes in
osteokinematic movement. Therefore any impair-
ment of articular cartilage can have a deleterious