Spotlight on...Cranial Cruciate Ligament Rupture
What is Cranial Cruciate Ligament Rupture?
The canine knee (stifle) is a complicated joint. Two major bones meet in this joint, the femur (thigh bone) and the tibia (shin bone). These are joined by the patella (knee cap) and fabellae (very small bones found at the back of the knee). The joint is held together and stabilised by various ligaments. These ligaments make sure that the knee can only bend in ways that it should. There are two cruciate ligaments, the cranial (towards the head) and the caudal (towards the tail). Besides these ligaments there are tendons that attach the bones to muscles and so enable movement of the joint, and menisci which act as shock absorbing cushions.
Within this complicated joint the cranial cruciate ligament has the job of preventing the tibia from moving forward under the femur. When it ruptures, partially or completely, the tibia is able to move forward. This abnormal function results in varying degrees of lameness. The ruptured ligament makes the joint unstable, causes pain, and damage to the joint (for example, tearing of the shock absorbing cushions). If left untreated your dog's lameness may appear to improve in the first week or so, but you will note that the joint looks swollen and lack of treatment simply means that the abnormal movement caused by the ruptured ligament will continue and further degeneration of the joint will occur. In the long term osteoarthritis will develop even in cases that are diagnosed and treated in the acute stages of this disease, but the progression is quicker in chronic cases.
Rarely traumatic, cranial cruciate ligament rupture is more usually the result of a disease process extending over months or years. It is caused by a combination of several factors including degeneration of the ligament, obesity, poor physical condition, conformation, and breed. Many dogs who suffer from cranial cruciate ligament (CCL) rupture in one knee will go on to develop a similar problem in their other knee, and partial tearing of this ligament frequently progresses to a full rupture over time.
What are the signs and symptoms of Cranial Cruciate Ligament Rupture?
The degree of lameness varies from cases to case, but in a case of complete CCL it is likely that you will observe your dog becoming suddenly lame. However, given that many dogs suffer partial tear and only progress to full rupture over time it is important to be alert to more subtle signs including your dog's inability to sit square and preference for putting his legs out to the side when sitting down. Other signs to look out for include:
difficulty jumping into the car
decreased activity level
muscle atrophy (decreased muscle mass in the affected leg)
decreased range of motion of the knee joint
a popping noise (which may indicate a meniscal tear)
swelling on the inside of the joint (fibrosis or scar tissue)
In chronic cases where the partial tear or rupture occurred some time ago the signs and symptoms will be akin to those seen with osteoarthritis:
unwillingness to play
In addition to taking a history from you, your veterinarian will manipulate the joint in order to test whether and to what extent the tibia is able to move forward under the femur. She may also take x-rays to confirm the presence of fluid in the joint, the progression of osteoarthritis, to aid in planning surgical treatment, and to rule out any other conditions that may be present. These x-rays will not enable your veterinarian to establish the extent of damage to the CCL or to the menisci. This can only be established through surgical investigation.
What treatments are available?
Surgical and non-surgical (also known as conservative) treatments are available, and your veterinarian will assist you in determining which is most appropriate for your dog. The most appropriate option for your pet will depend on your pets activity level, size, age, and conformation, the degree of knee instability, and other factors, such as the progression of osteoarthritis.
Surgical treatments are generally preferable when dealing with CCL rupture since they provide a means of permanently addressing the instability of the joint and any damage to the menisci. The surgical options available for controlling the joint's instability are varied and will depend on whether the surgery is carried out by general practitioner or a specialist.
Surgeons registered as specialists with the South African Veterinary Council may choose to use procedures such as the Tibial Plateau Levelling Osteotomy (TPLO) or Tibial Tuberosity Advancement (TTA), both of which seek to address and control the instability caused by the ruptured CCL by changing the biomechanics of the joint. Both of these techniques involve making a cut in the tibia. They are perceived to have superior results with regard to limb function and the progression of osteoarthritis compared to traditional suture techniques, and are often favoured in cases involving young, large breed dogs. The disadvantage of such techniques is related to the cut made in the bone which requires time to heal, and any problem with this healing or with an implant may require further surgery.
When surgery is performed by a general practitioner in South Africa you are more likely to be offered traditional suture techniques, particularly extra-articular (outside the joint) procedures. The most common is extracapsular suture stabilization. These techniques use strong suture material to mimic the CCL and prevent the tibia moving forward under the femur. The suture material allows normal function whilst preventing abnormal function and gives time for scar tissue to form and assume the role of stabilising the joint. The disadvantages of such techniques include rupture of the suture material and the progression of osteoarthritis, whilst the advantages include lower costs and lack of any bone cutting (and so the removal of complications associated with cutting the bone).
Non-surgical treatments generally involve pain management, restriction of activity, weight loss/control, therapeutic exercises and physical rehabilitation techniques to promote maintenance of function and management of osteoarthritis, and the use of custom knee braces or orthotics. These non-surgical treatments manage the patient's condition without addressing directly the stabilising role previously performed by the CCL. Nevertheless, physical rehabilitation therapy plays a crucial role in the post-operative recovery of surgical patients. It is highly recommended that such treatment begins immediately post-surgery.
How will treatment help this condition?
Prognosis for dogs treated surgically for CCL rupture is good, with clinical improvement being reported in 85-90% of cases. The surgical techniques address the instability of the joint either by changing the way it works by altering its biomechanics, or by mimicking the role performed by the intact CCL. Consequently, surgical intervention promotes normal function whilst preventing abnormal function. This enables as near a return to normal use of the knee as possible. Additionally, surgery allows for damage to the menisci to be assessed and addressed, something which is not possible with non-surgical treatments. This not only removes a source of pain and discomfort, but also an obstacle to full recovery, since dogs with torn menisci which are not removed will not return to near normal function of the knee. Unfortunately, osteoarthritis progresses regardless of the treatment option chosen and so management of this condition (read more about osteoarthritis) is necessary for the rest of your dog's life.
Post-surgical care is the highest priority in the treatment of CCL rupture. This will involve management of pain, restriction of exercise/activity, and physical rehabilitation techniques. In addition to medical management of pain, other techniques such as acupuncture, TENS (transcutaneous electrical stimulation), and cold therapy may be used to great effect to promote healing, relieve pain, and reduce inflammation. It can take dogs 6-7 months to walk normally following cruciate surgery, though physical rehabilitation can help to speed up this recovery and limit any complications.
Dogs can lose a third of the thigh muscle mass in their affected leg within 2 weeks of cruciate repair surgery and this muscle loss can continue for up to 5 weeks post-surgery. Therefore it is very important that physical rehabilitation begins immediately post-surgery and continues for at least 5 weeks. Initially physical rehabilitation helps to get your dog weight bearing as soon as possible after the surgery and so help to prevent muscle wasting. At Southern Cross we perform range of motion exercises and apply ice packs even before your dog leaves theatre following surgery. Our goal is to have your dog taking very good weight on the affected leg by the time of discharge which is about 3 days after the surgery.
At home you will need to keep your pet confined and make sure that he doesn't get the opportunity to run around, jump, or climb stairs or onto furniture. However, you will be given a home exercise plan by our physical rehabilitation trained veterinarian so that you can participate in your pet's recovery. This home exercise plan will complement the programme followed at our veterinary practice in the weeks after surgery, both as an inpatient and an outpatient, and will be adapted to suit the type of surgery your dog has undergone. Such a programme will include such techniques as passive range of motion, slow lead walking, massage, therapeutic exercises, hydrotherapy, and the use of cold and heat therapies. The aim of physical rehabilitation post-surgery will be to promote a return to as normal function as possible as quickly as possible by addressing muscle atrophy, joint use and function, gait, reduction of inflammation and pain relief.
Read more about physical rehabilitation for pets.