Diagram of a dog’s knee joint showing the cruciate ligaments.
Hindlimb lameness is the most common sign of CCL injury. This can either be sudden onset after exercise, or more gradual and progressive in nature. In some unlucky individuals both legs are affected at the same time leading to a dog that has great difficulty rising from rest and has a pottery gait.
In dogs with CCL disease a number of important changes are occurring in the joint:
- Osteoarthritis is present at the earliest stage (as a result of inflammatory processes brought about by fraying of the ligament) and results in painful lameness.
- The femur will roll back on the tibia every time the affected leg weight bears (this leads to mechanical lameness” and is a result of the loss of the mechanical stabilising function of the CCL).
- In some dogs where mechanical instability exists, other joint structures become subject to trauma and can be damaged (in particular a pair of joint cartilages, called menisci, can be crushed and torn by the femur slipping back down the slope of the tibia).
Diagnosis of CCL disease is normally by a combination of physical examination (whereby the joint is manipulated to check for the characteristic mechanical instability) and also radiographic changes. Normally a dog will need to be anaesthetised for this to be carried out thoroughly. For the majority of dogs diagnosed with CCL rupture, surgery will be recommended. Exceptions to this would be rare and generally involve those animals where the risk of anaesthetic or surgery is deemed too high. Dogs over 15kg have a very poor chance of ever using the leg properly without surgical intervention. Medical management in small dogs and cats is more favourable than for the larger dogs, but still involves a rehabilitation period of many months and is rarely a complete recovery.
There are a few options for the surgical management of CCL disease or rupture:
- Ligament replacement techniques
- Treatments which render the CCL redundant
- Libial Plateau Levelling Osteotomy (TPLO)
- Tibial Tuberosity Advancement (TTA)
- Modified Maquet Procedure (MMP)
The latter three treatments involve re-alignment of bone. Because bone healing is far more efficient than ligament healing, these are generally considered more robust than surgeries designed to replace the damaged ligament. The vast majority of dogs return to normal activity, with the owners unable to detect lameness at home, after the TPLO, TTA and MMP techniques.
This month’s case study looks at CCL using the MMP technique. As a practical aside, some insurance policy’s offer injury only cover – most of these will not cover cruciate rupture, even when seemingly sudden onset after an event on a walk, as it is considered a degenerative condition. A good reason to always check the small print when choosing an insurance policy!
Case Study : Cruciate surgery
Kai is a bouncy Springer Spaniel who recently turned 5 years old and has not had the best year. At the start of 2015 he had a sore leg, and after a week of painkillers and rest he was no better so investigations began.