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Cruciate Ligament Surgery for Dogs

The cruciate ligament disease is the most common orthopaedic condition treated worldwide in dogs. If you spend a short time looking at the internet, you will find at large amount of information (and sometimes misinformation!) about this debilitating condition. This page is designed to help the pet owner understand and choose options for their beloved but unfortunately, lame friend.

There are two cruciate ligaments within the dog's knee - the cranial and the caudal (anterior and posterior in humans - but essentially the same). The ligaments together prevent the tibia from sliding backwards and forwards in relation to the femur - in other words they provide a hinge.

The Cranial cruciate ligament is responsible for the forward stability of the tibia, the caudal cruciate is responsible for the backward stability of the tibia.

Due to the fact that a dog walks with a bent knee (compared to a human - with a straight/ vertical knee) there is a shearing force constantly placed during walking due to the orientation of the tibia compared to the femur. In other words - when the load is placed passively on the tibia, the tibia wants to push forwards. Additionally due to the orientation of the main muscle which is used to straighten the leg (the quadriceps), the tibia is actually actively pulled forward by this muscle every time a dog bears weight.

So due to a passive and active forces the cranial cruciate ligament (which stops the tibia moving forward remember) is always under strain when your dog is walking or running. With me so far?

It is in part due to these reasons that cranial cruciate ligament disease is so common - its just a really important ligament. As the diagram shows above, once the ligament has gone - the tibia slightly dislocates forward with every step.

There are other factors which are involved too -

1. Obesity - increases the load

2. Breed - certain breeds (Labradors, Boxers, Rottweilers) are more commonly affected, though any breed can be

3. Desexing - it is a little controversial but there is some evidence to suggest that cruciate ligament disease is higher in Labrador Retrievers when they have been desexed.

4. Activity level - a brief look at our yearly figures, strongly suggests that here on the Mornington Peninsula in Australia, we consistently do more cruciate surgeries in the summer months, with the peak month being often October - when dogs are often being walked on the beaches for the first time.

You might have noticed that I keep referring to the cruciate ligament rupturing as a disease or a condition. This is because rupture of the ligament is seldom associated with an actual trauma, the most common 'history' of a cruciate rupture (medical term for the backstory of a patient's  problem) is a progressive, intermittent, but deteriorating lameness, initially after exercise, but becoming more consistent over time. There are some cases where previous lameness has not been noted, but these are in fact, less common. 

In fact, often consistent lameness is often noted when the ligament is actually not completely ruptured, especially in athletic dogs, probably due to the swelling in the knee joint created by consistent micro-tearing of the ligament.

In the coming pages - we will discuss diagnosis, treatment options and let you see some of our surgeries and surgical protocols at Peninsula Vet Care. There will also be information for owners on what to expect on the day of your pet's surgery and also what it takes to look after a post op cruciate ligament case.

Dr Chris Franklin (Jan 2018)