WHAT IS IT?
The cranial cruciate ligament is a piece of strong tissue that sits inside the knee joint, and stabilises the top and bottom bones against each other. You may have heard of football or netball players rupturing their “ACL”, and this is the human equivalent. In dogs, rupture of the cruciate ligament tends to be more of an insidious and chronic process, eventually resulting in partial or complete tearing of the ligament and joint instability.
WHAT CAUSES IT?
There are multiple factors that can contribute to disease of the cranial cruciate ligament, and typically we see a couple of different clinical pictures. One is a younger or middle aged, healthy and active dog who presents with lameness after a bout of exercise. At risk breeds for this type of rupture include Golden Retriever, Rottweiler, Mastiff, Newfoundland, Akita, St Bernard, and Staffordshire Bull Terrier. The other scenario we see are older, often overweight dogs where the lameness has been mild but chronic, with a sudden worsening.
HOW IS IT DIAGNOSED?
There are several key signs that your veterinarian will look for to ascertain whether your dog has ruptured their cruciate ligament. These include swelling of the joint, pain on extension of the knee, and the “drawer sign”. The drawer sign is where there is forward and back instability of the bottom bone (the tibia) compared to the top bone (the femur) in the knee joint. Sometimes a dog needs to be sedated in ordered to determine whether there is instability here. A positive drawer sign indicates that the cruciate ligament no longer has integrity. The difficulty with cruciate disease diagnosis is when there is a partial tear. Swelling in the knee, pain on extension and even the smallest amount of movement between the two bones may indicate a partial rupture, and the earlier we detect this and the sooner we repair the knee joint, the better prognosis for future mobility for your dog.
HOW IS A CRUCIATE RUPTURE REPAIRED?
There are several different techniques to repair a ruptured cruciate ligament. The technique your veterinarian recommends will depend on your dog’s size, their activity levels and the surgeon’s experience. The two main techniques we offer at Busselton Veterinary Hospital are called a Lateral Tie repair, for small and inactive dogs, or a Triple Tibial Osteotomy for large or highly active dogs. For more information on these please contact us.
WHAT HAPPENS IF WE DON’T HAVE SURGERY?
Without an intact cruciate ligament there is instability in the knee joint causing abnormal wear and tear between the cartilages and bones, and the joint begins to develop degenerative changes. These changes result in bone spurs developing which cause chronic pain and impairment of joint function. This process can be halted or slowed by surgery, but cannot be reversed. If surgery is not performed your pet will require lifelong pain management, which may include pain relief, Zydax injections, weight control, physiotherapy and supplements.
ARE THERE ANY CONSEQUENCES TO A RUPTURED CRUCIATE?
There are shock absorbing cartilages in the knee called menisci. These crescent shaped pieces of tissue sit between the two bones of the knee joint and cushion impact as the animal weight bears. If the knee joint is unstable, weight bearing produces a shearing force, which can crush and tear the menisci resulting in more pain and chronic inflammation. This sequelae is almost definitely going to occur if the surgery is not performed, but cannot be 100% prevented even with surgery. The menisci are visualised during the time of cruciate repair and if they are damage can be removed. Rarely several weeks or months after the initial surgery, a patient will become acutely sore again indicating a meniscal tear, and another surgery is required to treat this process.
MAGGIE’S SURGICAL JOURNEY
Dr Richard performs many cruciate repairs at our hospital. Below is a series of videos which step out Maggie’s bilateral cruciate repair that he did. It is a great way to get an insight into what happens throughout the repair journey
Written by Dr Aimee Burrows