EXOTICS
The craniomedial band is taut in both flexion and
extension, while the caudolateral band is only taut in
extension. For this reason, the craniomedial band is
often the first portion of the ligament to fail. 1 These
patients are considered to have a partial tear, and
medical management of these cases has shown
variable success depending on the techniques used.
Diagnosing a CCL tear
High suspicion of partial or complete CCL tear is
typically identified on physical examination coupled
with two-view stifle radiographs. The most common
physical exam findings include stifle joint effusion,
medial buttress (with chronicity) along with cranial
drawer sign and tibial thrust. Cranial drawer sign may
only be present on flexion of the limb in patients with
a partial CCL tear. These patients also tend to be
painful on hyperextension of the stifle. Radiographs
will typically confirm evidence of joint effusion and
may show signs of osteoarthritis in the joint. Some
patients may also show the tibia cranially displaced (in
drawer) when compared with the femur (Figure 1).
Minimally invasive procedures including standard
stifle arthroscopy or, more recently, arthroscopy via
needle scope may also be used as a diagnostic tool to
confirm the diagnosis of a partial or complete CCL tear
Magnetic resonance imaging (MRI) is an uncommon
diagnostic tool used for identification of CCL tears or
meniscal disease in veterinary medicine at this time.
Non-surgical management
articular structures should be evaluated, with special
attention paid to the articular surfaces of the femur, tibia
and patella as well as the long digital extensor tendon,
both the cranial and caudal cruciate ligaments and
the medial and lateral menisci. Meniscal tears should
be debrided if present. There’s also continued debate
over the procedure known as a “meniscal release.”
This technique involves transection of the caudal
attachments of the medial meniscus with the goal
of reducing the risk of subsequent meniscal tearing.
However, it has been shown to result an increased
contact area of the medial joint compartment,
contributing to accelerated development of
osteoarthritis in the stifle joint. 7
Intra-articular stabilisation techniques are the
mainstay of human anterior cruciate ligament (ACL)
repairs. These techniques employ harvesting a
biologic graft from another tendon in the body or
from a cadaver and then drilling bone tunnels and
replacing the torn ACL. The graft will then go through
a period of devitalisation, followed by revascularisation
and ligamentisation over an approximately 20-week
period. During this time, the graft is at a diminished
tensile strength, and overuse may lead to graft failure
and returned stifle instability. More recent research
has focused on synthetic intra-articular replacement
or biologic scaffolds as opposed to the biological
replacement techniques that have fallen out of favour
in the veterinary surgical field. Today, however, most
surgeons are finding themselves electing extra-
articular or biomechanical stabilisation techniques.
Medical management options for partial CCL tears may
consist of varying combinations of rest, nonsteroidal
anti-inflammatory drugs (NSAIDs), nutraceutical use
and physical therapy. But more recently platelet-
rich plasma (PRP) and/or canine stem cells derived
from bone or fat have been used with varying and,
unfortunately, inconsistent success. 5 There’s also an
argument that early surgical intervention in patients
with partial tears may help in preserving the remainder
of the intact ligament and that these patients may
have a better postoperative success.
Surgical management options
Surgical options for these patients are broken down
into two general categories: ligament replacement
versus biomechanical techniques. More recent
literature has suggested that using a combination of a
ligament replacement and biomechanical techniques
may result in a more stable stifle joint postoperatively. 6
Ligament replacement techniques can be further
subdivided into intra-articular or extra-articular
techniques.
Regardless of stabilisation procedure, it’s routine to
first perform a joint exploration. This may be achieved
by an open arthrotomy or arthroscopically. All intra-
Figure 2: Left Stifle, lateral view. Immediate postoperative TPLO.
Issue 03 | JULY 2018 | 7