Does your pet have knee problems? Could your dog have a ruptured cruciate?  How about a luxating patella? 

Ruptured Cruciate

Diagnostic Imaging Atlas

Diagnostic Imaging Atlas

We  know that people get injuries to their cruciate ligaments (like  athletes who damage their ACL), but we were surprised to learn that dogs  suffer the same problems.

What are the cruciate ligaments?

Cruciate means "crossed" or "X" in Latin.  There are two cruciate ligaments that form an “X-shape” within the stifle (AKA, knee) joint.  There main function is to stabilize the knee joint.  The  caudal cruciate ligament prevents the tibia from caudal instability  (tibia moving independently towards the tail), and the cranial cruciate  ligament prevents independent movement of the tibia in the cranial  direction (towards the head).  The cranial cruciate is more commonly injured.

Why is the stifle so likely to be injured?

The  knee joint is one of the weakest joints in both dogs and humans because  it is composed of multiple ligaments which stabilize it.  The femur sits on top of the tibial plateau, while the cruciate ligaments keep it there.  Some  dogs have a steep tibial plateau (e.g. Rottweilers, Labradors, etc)  which can predispose the cranial cruciate ligament to injury.  If the ligament ruptures, it results in acute lameness.  

How is cruciate rupture diagnosed?

Diagnostic Imaging Atlas

Diagnostic Imaging Atlas

The  most reliable means of diagnosing the injury is to move the femur  and  tibia in a “front to back” direction to demonstrate the  instability.  This movement is called the “drawer sign”.  Also,  the  tibial compression test is used to determine if the upper tibia  will  move forward (tibial thrust) when the hock or ankle is flexed.  Tibial  thrust causes pain when elicited.  A positive drawer sign and tibial  thrust can only occur once the the cranial cruciate ligament has been  ruptured. 

Will my dog require sedation for an orthopedic exam or for other diagnostics?

  Often cranial cruciate rupture can be diagnosed while the dog is awake,  but .  However  if the dog is experiencing severe pain, has very strong  muscles, or is  uncooperative, he or she may require sedation in to  order examine the  joint thoroughly.

How is cranial cruciate ligament injury treated?

   Most dogs are very painful and reluctant to use the affected limb, and  most dogs require surgical stabilization. TVRH stabilizes these joints  using two different techniques:

Extracapsular stabilization   is used to stabilize knees in small to medium or less active dogs.   A    heavy nylon suture anchors the lower femur to the upper tibia   simulating the cranial cruciate ligament.

tibial plateau leveling osteotomy (TPLO)   is used in  larger, active dogs. This  technique involves cutting the bone associated  with the tibial plateau  and leveling head of the tibia so that the femer will not  slide off the back.   Then a plate and screws are used to fix the tibial  plateau osteotomy in a flat tabletop position.

Patients  who are managed conservatively usually develop  osteoarthritis,  persistent pain, decreased range of joint motion and  are likely to  develop meniscal injury if surgery is not performed.  The   purpose of surgery is to stabilize the joint, alleviate discomfort and   to the slow the progression of impending osteoarthritis.


If your pet suffers from a knee problem and you would like to request a surgical consult, please fill out the following form.

Once you have submitted this form, we will contact you and your primary care veterinarian to set up the referral. Then we will schedule an appointment for you and your pet to come into our hospital to meet with our specialist.

Name *
Your primary care veterinary clinic's phone number *
Your primary care veterinary clinic's phone number

Luxating Patellas

What is a luxating patella?

The patella, or knee-cap, is a small, flat, bone that covers and protects the knee joint.  Medial patellar luxation occurs when the patella is displaced from the trochlear sulcus.  It is more commonly seen in small or toy dog breeds but can also occur in large breed dogs. 

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There are four grades of severity:

Grade I: The dog generally shows no lameness but displacement can be manually induced.

Grade II: The dog will sometimes ‘skip’ while running or walking and the patella can be manually displaced with lateral pressure.

Grade III: The dog occasionally skips and becomes non weight-bearing on the leg.  In these cases the patella remains displaced most of the time and can be manually reduced when the stifle is extended.

Grade IV: The dog will walk with rear in a crouched position, the patella is permanently displaced and cannot be manually repositioned.  In the case of Grade IV deformities are seen in the femur and tibia.

How is a luxating patella diagnosed?

During a physical exam the doctor will try to manually displace the patella and determine the severity of the luxation.  For grades III and IV radiographs will show the displaced patella.  CT scans will also aid in the determining of a luxation as well as any deformities in the femur or tibia.