What is the cruciate ligament?

There are two cruciate ligaments in the stifle (knee). They attach the femur (thigh bone) and to the tibia (shin bone) and allow some degree of twisting, allow the stifle to flex and extend, and importantly stabilise the joint – preventing front-to-back slippage.

Of the two ligaments, the one that almost always gets damaged is the anterior cruciate ligament.

How does the cruciate rupture?

Often, only a simple slip on uneven ground, slippery floor or sand will damage the ligament. Certainly turning sharply while running at full speed, or leaping, e.g. to catch a ball, and landing badly are common causes of cruciate rupture.

When the leg twists, it tightens the cruciate ligaments around each other and it then only takes a relatively small sideways force to rupture one of the cruciates. Sometimes, instead of the cruciate ligament rupturing, the bone where it inserts into the femur is actually pulled off (avulsion fracture).

What happens after the rupture occurs?

The stifle joint becomes immediately unstable, with the tibia being forced forward relative to the femur. There is sudden and intense pain due to the severe stretching of the structures around the joint, in particular the joint capsule. Inflammatory fluid also fills the joint, further intensifying pain and thinning the lubricating joint fluid and producing destructive inflammatory enzymes that attack the cartilage. Continued instability combined with the above effects causes rapid erosion of cartilage with subsequent irreversibly bony changes; that is, arthritis.

How is cruciate rupture diagnosed?

In many cases, palpation (examination by touch) of the injured stifle will reveal a positive anterior draw sign (abnormal forward movement of the tibia in relation to the femur). Sometimes the stifle joint is too painful to allow satisfactory palpation and sedation is required. Because of the number of different types of traumatic injuries that can occur in the stifle, a general anaesthetic, X-rays and palpation are recommended.

What is the recommended treatment?

The only satisfactory way of treating a ruptured cruciate ligament is to perform surgery. Surgery replaces the function of the original ligament with a synthetic prosthesis that therefore stabilises the joint, limiting the degenerative joint disease that leads to severe arthritis. The prosthesis is placed around the fabella bone and through its tough ligamentous attachment to the femur, and through the bony ridge at the top front of the tibia. The prosthesis is left in the leg permanently.

What other damage can occur as a result of the cruciate rupture?

In 40% of cases there is also damage to the meniscus (cartilage) in the stifle. Because of this, it is now highly recommended that the injured joint be thoroughly explored (arthrotomy) and any torn cartilage be surgically removed. Damaged cartilage left in the joint will cause ongoing lameness of varying severity and accelerate arthritic degeneration. The tags or stumps of the ruptured cruciate ligament leak inflammatory enzymes that cause ongoing degeneration of the joint cartilage. These ligament tags are removed during the arthrotomy.

All stifles that have suffered any ligament damage, will start to undergo progressive degenerative arthritic changes – even if surgery is performed immediately; rapid degeneration before surgery and greatly slowed after surgery, but progressive none-the-less. For this reason the protective Cartrophen course is highly recommended.

My dog’s cruciate was found to be partially torn and not ruptured: what treatment is advisable?

According to studies done on partial ruptures, almost all rupture soon after the partial tear – usually within a few weeks to months. However, complete cage confinement for three months reduces the chance of full rupture. Stabilisation of the joint, using the same technique as for cruciate rupture, provides strong support for the partially torn ligament and allows it to heal. Because damage in the joint is limited and the joint stabilised, the result is far better long-term than if the ligament had ruptured. Cartrophen is still recommended.

What special instructions are there for post-operative care?

Post-anaesthetic and surgical wound management will be covered in a detailed information sheet upon your dog’s discharge. Regarding the cruciate repair, please allow complete rest for 14 days. Confine in a cage if necessary and keep separate from other dogs and sources of excitement. After 14 days you may begin slow, short but gradually increasing lead walks (a few metres only initially). You will find that your dog will prefer to carry its leg if it goes any faster than a walk. A slow walk encourages use of the recovering leg.

The rate of recovery is highly variable and depends on the amount of damage sustained by the joint, the length of time until surgery, the individual patient’s rate of healing, the rate of development of arthritic degeneration and the ability of the owner to provide a confined, non-slippery environment and limit excitable behaviour. Generally the quickest healers will appear almost 95% to 98% better within eight weeks, but up to 12 weeks is more common.

Will my dog require pain relief?

Yes, most definitely. Pain relief is always provided in surgery and is recommended to be maintained for as long as is required. For most dogs, two to three weeks is usually adequate. The most appropriate pain relief that does not erode the already compromised cartilage and does not antagonise the function of Cartrophen, is Rimadyl or Previcox. Pain is minimised by looking after the patient and limiting activity, and providing a safe, comfortable environment. Remember that your dog has undergone orthopaedic surgery, which causes discomfort for many months in humans. A common problem is over-activity too soon after surgery, causing inflammation in the tissues around the prosthesis due to excessive movement between the prosthesis and the adjacent tissue. Once healing is complete, the prosthesis is surrounded and imbedded in fibrous scar tissue and causes no pain.

What is the cruciate ligament?

There are two cruciate ligaments in the stifle (knee). They attach the femur (thigh bone) and to the tibia (shin bone) and allow some degree of twisting, allow the stifle to flex and extend, and importantly stabilise the joint – preventing front-to-back slippage.

Of the two ligaments, the one that almost always gets damaged is the anterior cruciate ligament.

How does the cruciate rupture?

Often, only a simple slip on uneven ground, slippery floor or sand will damage the ligament. Certainly turning sharply while running at full speed, or leaping, e.g. to catch a ball, and landing badly are common causes of cruciate rupture.

When the leg twists, it tightens the cruciate ligaments around each other and it then only takes a relatively small sideways force to rupture one of the cruciates. Sometimes, instead of the cruciate ligament rupturing, the bone where it inserts into the femur is actually pulled off (avulsion fracture).

What happens after the rupture occurs?

The stifle joint becomes immediately unstable, with the tibia being forced forward relative to the femur. There is sudden and intense pain due to the severe stretching of the structures around the joint, in particular the joint capsule. Inflammatory fluid also fills the joint, further intensifying pain and thinning the lubricating joint fluid and producing destructive inflammatory enzymes that attack the cartilage. Continued instability combined with the above effects causes rapid erosion of cartilage with subsequent irreversibly bony changes; that is, arthritis.

How is cruciate rupture diagnosed?

In many cases, palpation (examination by touch) of the injured stifle will reveal a positive anterior draw sign (abnormal forward movement of the tibia in relation to the femur). Sometimes the stifle joint is too painful to allow satisfactory palpation and sedation is required. Because of the number of different types of traumatic injuries that can occur in the stifle, a general anaesthetic, X-rays and palpation are recommended.

What is the recommended treatment?

The only satisfactory way of treating a ruptured cruciate ligament is to perform surgery. Surgery replaces the function of the original ligament with a synthetic prosthesis that therefore stabilises the joint, limiting the degenerative joint disease that leads to severe arthritis. The prosthesis is placed around the fabella bone and through its tough ligamentous attachment to the femur, and through the bony ridge at the top front of the tibia. The prosthesis is left in the leg permanently.

What other damage can occur as a result of the cruciate rupture?

In 40% of cases there is also damage to the meniscus (cartilage) in the stifle. Because of this, it is now highly recommended that the injured joint be thoroughly explored (arthrotomy) and any torn cartilage be surgically removed. Damaged cartilage left in the joint will cause ongoing lameness of varying severity and accelerate arthritic degeneration. The tags or stumps of the ruptured cruciate ligament leak inflammatory enzymes that cause ongoing degeneration of the joint cartilage. These ligament tags are removed during the arthrotomy.

All stifles that have suffered any ligament damage, will start to undergo progressive degenerative arthritic changes – even if surgery is performed immediately; rapid degeneration before surgery and greatly slowed after surgery, but progressive none-the-less. For this reason the protective Cartrophen course is highly recommended.

My dog’s cruciate was found to be partially torn and not ruptured: what treatment is advisable?

According to studies done on partial ruptures, almost all rupture soon after the partial tear – usually within a few weeks to months. However, complete cage confinement for three months reduces the chance of full rupture. Stabilisation of the joint, using the same technique as for cruciate rupture, provides strong support for the partially torn ligament and allows it to heal. Because damage in the joint is limited and the joint stabilised, the result is far better long-term than if the ligament had ruptured. Cartrophen is still recommended.

What special instructions are there for post-operative care?

Post-anaesthetic and surgical wound management will be covered in a detailed information sheet upon your dog’s discharge. Regarding the cruciate repair, please allow complete rest for 14 days. Confine in a cage if necessary and keep separate from other dogs and sources of excitement. After 14 days you may begin slow, short but gradually increasing lead walks (a few metres only initially). You will find that your dog will prefer to carry its leg if it goes any faster than a walk. A slow walk encourages use of the recovering leg.

The rate of recovery is highly variable and depends on the amount of damage sustained by the joint, the length of time until surgery, the individual patient’s rate of healing, the rate of development of arthritic degeneration and the ability of the owner to provide a confined, non-slippery environment and limit excitable behaviour. Generally the quickest healers will appear almost 95% to 98% better within eight weeks, but up to 12 weeks is more common.

Will my dog require pain relief?

Yes, most definitely. Pain relief is always provided in surgery and is recommended to be maintained for as long as is required. For most dogs, two to three weeks is usually adequate. The most appropriate pain relief that does not erode the already compromised cartilage and does not antagonise the function of Cartrophen, is Rimadyl or Previcox. Pain is minimised by looking after the patient and limiting activity, and providing a safe, comfortable environment. Remember that your dog has undergone orthopaedic surgery, which causes discomfort for many months in humans. A common problem is over-activity too soon after surgery, causing inflammation in the tissues around the prosthesis due to excessive movement between the prosthesis and the adjacent tissue. Once healing is complete, the prosthesis is surrounded and imbedded in fibrous scar tissue and causes no pain.