The knee joint has two stabilising ligaments deep in the middle of the joint and these cross over one another like an X and are called the Cruciate ligaments. They are attached to the bottom of the femur at one end and to the top of the tibia at the other end. In pets, mainly dogs but also cats, the anterior (or canial) cruciate can rupture, resulting in acute lameness, holding the affected hind leg off the ground. This a common knee injury in footballers. When we examine these lamenesses we can detect the poor stability by looking for a "draw forward" movement, where we move the lower leg forward, with respect to the leg above the knee. This movement, or "draw" is diagnostic of the condition and surgery is needed to create stability once more. Some can be partial tears which appear to settle then become suddenly much worse, because the ligament finally ruptures.
These breeds can be more at risk - Labrador Retriever, Golden Retriever, Rottweiler, Mastiffs, Boxer, Newfoundland, West Highland White Terrier, however, any dog breed can suffer from cruciate ligament rupture. Though rupture can happen purely due to trauma, it is well known that the ligament becomes weaker with age in some breeds and when one ruptures, it is not uncommon to have a ruture in the same ligament in the othe knee, some months later.
There are several ways of fixing these and which one is used often depends on the size of the dog. Damage to the miniscal cartillage is also common at the same time and may also need repair at surgery.
Methods we use at Parkside are
- Lateral fabellar inbrication suture
- Locking Loop method
- Tibial plateau levelling osteotomy (TPLO)
The most used method is the first one which involves a thick nylon suture material being placed in order to gain stablity and is used in most small and medium sized dogs. The locking loop method is relatively new, using a very specialised suture material and inserted into bone tunnels to gain the stability required. TPLO is the one of choice for large breeds and we use the "Slocum Method", for which partner Stuart has undergone training in America. This involves cutting the top of the tibia in a curve using a specially designed jig and curved bone saw, then rotating this part in order to level the bearing surface (plateau). This takes the "pull" off the ligament and allows it to heal.
The Cranial Cruciate Ligament (CCL) is always under some degree of tension when a pet exercises and it is this tension that keeps pulling it apart and so not allowing natural healing to take place after a rupture. This is why surgery is required to effect repair.
U-Tube video from Vetsoria explains more - CLICK HERE