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Footballer's Knee- an article about cruciate ligament rupture

Paddy is a very sweet and very strong- willed little dog. His owners tell me that he is king of the roost at home and bosses both the other dogs around. I saw Paddy a couple of weeks ago because his owners had noticed that for some time he had occasionally been carrying one back leg. He would run about and then suddenly hold his leg up and simply run on three legs.

My immediate thought was that he had what we call a luxating patella. This is where the knee cap pops in and out of joint and it is fairly common in small dogs like terriers. We booked a day to have Paddy in to sedate so we could have a good feel of his joints and xray his legs if necessary.

Under sedation it was immediately obvious that both his patellae were very stable indeed and were not the cause of his problem. The next thing I felt for is a movement called ‘cranial draw’. This is when you can move the tibia forward with respect to the femur. Paddy’s right knee showed a marked draw and his problem was apparent. He had ruptured his cruciate ligament. This was somewhat of a surprise because it is an injury we most commonly see in large, heavy or long- legged dogs like Newfoundlands or Setters.

There are two cruciate ligaments in each knee and they form a cross shape- hence their name. The cranial one runs from the front of the tibia to the back of the femur and its job is to stop the bones moving forwards and backwards over each other. If the ligament ruptures the joint becomes very unstable and the dog cannot bear weight. It is this ligament that Paul Gascoigne famously ruptured and is a fairly common footballing injury because of all the twisting strains on the knee.

I spoke to Paddy’s owner and explained his problem. It made most sense to get on and operate while we had him asleep- they readily agreed.

There are several techniques for repair and everyone has their favourite. Mine is called an ‘over the top’ repair and involves making a graft from tissue in the thigh and using this to thread back through the knee and over the top of the joint- hence the name.

I made a long incision in Paddy’s leg to allow me to gather the graft. I made this by removing a section of the ‘fascia lata’. This is a tough, smooth covering over the muscle of the thigh. I cut a strip from this but left it attached at the bottom end at the front of the tibia. I left the graft tucked out of the way while I opened up the knee joint itself. This is so I could remove any strands of the old ligament and check for damage to the other structures in the knee like the cartilage.

Once I was happy it was time to get down to the nitty- gritty part and, as the pictures show, the part that looks fairly brutal!

I started to separate all the tissues towards the back of the knee to get access to that part. I felt behind the knee with my little finger and found the hole at the back of the femur that would be my landmark. I then got my graft- passer. This is a curved, metal instrument with a slit in the end. I used my finger as a guide and started to push the passer round towards the back of the femur and into the joint. With a little ‘gentle’ persuasion I pushed the passer right through the knee joint and out the front. I then threaded the free end of my graft I’d made earlier into the slit in the end of the passer. You need to be careful at this point to leave enough slack so as not to break the graft on the way back through, which would be disaster!

Once threaded I started to gently but firmly pull the hook back the way it had come. As it passes back through it takes the free end of the graft back through the knee. The free end is then pulled out of the passer and round to the side of the knee over the top of the end of the femur. In this way the graft follows the exact same route that the original ligament did.

I then used some very strong, dissolvable material to stitch the end of the graft in place as tightly as I could. Once this was done it was just a matter of starting the long process of stitching all the layers back together.

Paddy was given strong pain- relief throughout and was sent home with pain- killers and strict instructions not to let him do too much. This proved difficult because of his nature but his owners persevered. The rest after the operation is vital to allow time for the graft to heal while it is relatively weak. Terriers can be trouble after this kind of operation because they are so good at getting around on three legs so we need to find a balance between rest and not letting the muscles seize up or allowing the dog time to decide not to use the leg!

I saw Paddy after a week and he was already starting to bear weight on his leg. His owner sheepishly admitted that in a split second of back- turning Paddy had jumped onto the wall in the back garden as he liked to do before his operation! I guessed he wasn’t too bothered by his leg!

Paddy will need about six weeks of relative inactivity and a gradual increase in exercise but so far he seems to be doing just fine. His big character in his little body is all he needs to make a speedy return to form!

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