« Back to Orthopedic
What is cranial cruciate ligament rupture?
The cranial cruciate ligament (CrCL) is a fibrous band of tissue
located deep within the stifle joint (knee). This ligament is
responsible for maintaining joint stability when your pet is
standing, walking, or running. Tearing or "rupture" of the CrCL
causes joint instability, which leads to joint swelling, pain, and
lameness. In dogs, osteoarthritis (degenerative joint disease) will
develop if this instability is not corrected. Rupture of the CrCL
is one of the most common causes of hind limb lameness in dogs, and
it occurs less commonly in cats.
Arthroscopic view of a normal cranial cruciate ligament
(asterisks) in the right knee. Note the smooth, taut appearance of
the ligament beneath the probe in the right panel.
Two examples of ruptured cranial cruciate ligaments from right
knees (asterisks). In the left panel the ligament is loose
(incompetent) and non-functional. The ligament is being examined
with an arthroscopic probe. In the right panel the ligament is
completely ruptured and the ligament fibers are frayed and rounded.
A probe is positioning the ruptured ligament for photography.
Humans have a similar ligament in their knee, the anterior
cruciate ligament (ACL). Most humans tear their ACL during certain
athletic maneuvers. Dogs rupture the CrCL either acutely (suddenly)
or chronically (over time). Dogs with an acute rupture show no
evidence of hind limb lameness or pain before the injury. They
suddenly develop severe hind limb lameness, usually during
strenuous activity. In contrast, dogs with a chronic rupture
develop slow, progressive, hind limb lameness and reluctance to
exercise that comes and goes over weeks to months.
Once the CrCL is ruptured, there is an increased risk for
damaging other support structures within the knee. One important
supporting structure that is commonly damaged along with CrCL
rupture is the medial meniscus, a C-shaped piece of fibrocartilage
that functions as a shock-absorber and allows the bones above and
below the knee joint to interact more effectively.
LEGEND: * (asterisk):
meniscus | MFC: articular cartilage of the femur | TP: articular
cartilage of the tibia
Arthroscopic view of the medial meniscus. A) Normal, healthy
meniscus. B,C,D) Representative examples of the classic "bucket
handle tear" of the medial meniscus. These tears are detected by
examining the meniscus with an arthroscopic probe. Once detected,
the injured portion of the meniscus is removed, which eliminates
pain and improves limb use after surgery. E,F) Examples of the
remaining medial meniscus after removal of meniscal tears.
What are the treatment options for cranial cruciate ligament
We recommend surgical stabilization of the knee in almost all
cases of CrCL rupture. As in humans, many procedures have been
developed to stabilize the affected knee. None of these procedures
is perfect, meaning that there is not 100% success in every case.
The two common procedures we perform at Texas A&M are the
tibial plateau leveling osteotomy (TPLO) and the extracapsular
stabilization ("Extra-cap"). Depending on your pet's age, size, and
activity, we may recommend one procedure over the other. In many
cases, your pet may qualify for either procedure. Regardless of
which procedure is performed, we typically begin the surgery by
examining the knee joint using arthroscopy. During this part of the
surgery, the inner structures of the joint, such as the torn
ligament and meniscus, are examined and treated using small skin
incisions, an arthroscopic camera, and small arthroscopic
instruments. Advantages of arthroscopic treatment include smaller
skin incisions, decreased blood-loss during surgery, improved
visualization and treatment of the internal structures of the
joint, less pain after surgery, and a faster return to using the
Occasionally dogs or cats with CrCL rupture will not qualify for
surgery, most commonly because they are at high risk for anesthesia
or have other life-threatening medical conditions. In these cases
we recommend treating your pet's knee pain and arthritis with
conservative therapy. Conservative treatments may include
administration of joint supplements (Adequan ®, Cosequin ®,
Dasuquin ®), pain medications, weight loss, rehabilitation, and in some cases
administering injections of anti-inflammatories and joint
lubricants directly into the joint. Many dogs can be made
comfortable for some time with conservative treatment; however,
arthritis, pain, and lameness eventually worsen.
If my pet has ruptured its cruciate ligament and I want to
pursue additional consultation or treatment at Texas A&M, how
can I schedule an appointment?
Appointments can be scheduled with the Orthopedic Surgery
Service by contacting the Veterinary Medical Teaching Hospital
Monday through Friday at 979-845-2351. Either you or your
veterinarian can make the initial phone call, but we will need to
speak with your veterinarian prior to confirming the final
« Back to Orthopedic
↑ Back to Top