ACL: Cruciate Ligament Injury & Repair FAQ
What Happens in Surgical Repair?
Here at Prairie View Animal Hospital we offer three different surgical repair techniques for CCL injuries; the lateral suture technique, the TTA procedure, and the tightrope technique. Your pet?s age, size, and activity level, as well as financial constraints will dictate which procedure we recommend.
The Lateral Suture Technique:
The knee joint is opened and inspected. The torn or partly torn cruciate ligament is removed. Any bone spurs of significant size are bitten away with an instrument called a rongeur. If the meniscus is torn, the damaged portion is removed. A wire or a very large, strong suture is passed around the fabella behind the knee and through a hole drilled in the front of the tibia. This tightens the joint to prevent the drawer motion, effectively taking over the job of the cruciate ligament. The wire or suture placed will break 2 to 12 months after surgery and the dog?s own healed tissue will hold the knee.
The TTA (Tibial Tuberosity advancement) Procedure:
The TTA represents another take on how to use the biomechanics of the knee to create stabilization. The idea is that when the cruciate ligament is torn, the tibial plateau (the top of the tibia) and the patellar ligament should be repositioned at 90 degrees to one another to combat the shear force generated as the dog walks. To make this happen, the tibial tuberosity (front of the tibia where the patellar ligament attaches) is separated and anchored in its new position by a titanium or steel cage, fork, and plate. Bone grafts are used to assist healing. This procedure was developed in 2002 at the University of Zurich and since then over 20,000 patients worldwide have had this surgery. Some experts prefer it to the TPLO while others prefer the TPLO. Both procedures require specialized equipment and expertise.
- Typically the leg is bandaged for a week after surgery.
- The patient?s activity must be restricted and post-operative confinement is a must with gradually increased activity over 3 to 4 months. Most dogs can return to normal activity by 4 months after surgery.
The Tightrope technique:
The TightRope CCL technique was developed to provide a minimally invasive method for extracapsular stabilization of the cranial cruciate ligament-deficient canine stifle. TightRope CCL seeks to optimize the lateral suture stabilization technique by employing bone-to-bone fixation, an implant with superior strength and stiffness designed specifically for ligament repair, and a method for consistent isometric implant placement. As such, TightRope CCL can counteract cranial tibial thrust, drawer, and internal rotation, while providing optimal joint range of motion. Please visit www.arthrexvetsystems.com for additional information.
What and where are the cruciate ligaments?
There are two bands of fibrous tissue called the cruciate ligaments in each knee joint. They join the femur and tibia (the bones above and below the knee joint) together so that the knee works as a hinged joint.
They are called cruciate ligaments because they ?cross over? inside the knee joint. One ligament connects from inside to outside the knee joint and the other outside to inside, crossing each other in the middle.
How does a cranial cruciate injury occur?
The knee joint is a hinged joint and only moves in one plane, backwards and forwards. Traumatic cruciate damage is caused by a twisting injury to the knee joint. This is most often seen in dogs when running and suddenly changing direction so that the majority of the weight is taken on this single joint. This injury usually affects the anterior or cranial (front) ligament. The joint is then unstable and causes extreme pain, often resulting in lameness.
The injury also occurs commonly in obese dogs, just by stumbling over a pebble while walking. A more chronic form of cruciate damage can occur due to weakening of the ligaments as a result of disease. The ligament may become stretched or partially torn and lameness may be only slight and intermittent. With continued use of the joint, the condition gradually gets worse until rupture occurs.
How is it diagnosed?
With traumatic cruciate rupture, the usual history is that the dog was running and suddenly stopped or cried out and was then unable to bear weight on the affected leg.
? Many pets will ?toe touch? and place only a small amount of weight on the injured leg.
? During the examination, the veterinarian will try to demonstrate a particular movement, called a drawer sign. This indicates laxity in the knee joint. Many dogs will require mild sedation before this test can be performed. Other diagnostic tests such as radiographs (x-rays) may also be necessary.
Is other joint damage common?
We mentioned the meniscus as part of the knee joint. The bones of all joints are capped with cartilage so as provide a slippery surface where the bones contact each other (if the bones contact each other without cartilage, they grind each other down). In addition to these cartilage caps, the stifle joint has two ?blocks? of cartilage in-between the bones. These blocks are called the menisci and serve to distribute approximately 65% of the compressive load delivered to the knee. The only other joint with a meniscus is the jaw (tempero-mandibular joint).
When the crucial ligament ruptures, the medial (on the inner side of the knee) meniscus frequently tears and must either be removed, partly removed, or - ideally - repaired. This is generally done at the time of cruciate ligament surgery and we would be remiss not to mention it.
Pets with meniscal damage may have an audible clicking sound when they walk or when the knee is examined, but for a definitive diagnosis the menisci must actually be inspected during surgery. It is difficult to access the menisci and thus repairing a tear in the meniscus is problematic; furthermore, poor blood supply to the menisci also makes good healing less likely. For these reasons, removal of the damaged portion of the meniscus is the most common surgical choice. This leaves some meniscus behind to distribute the compression load on the knee but removes the painful, ineffective portion.
Areas of current research include techniques to improve blood supply to the healing meniscus so that repair can be more feasible. If meniscal damage has occurred in a cruciate rupture, arthritis is inevitable and surgery should be considered a palliative procedure.
What Happens if the Cruciate Rupture is Not Surgically Repaired?
Without an intact cruciate ligament, the knee is unstable. Wear between the bones and meniscal cartilage becomes abnormal and the joint begins to develop degenerative changes. Bone spurs called osteophytes develop and chronic pain and loss of joint motion result. This process can be arrested by surgery but cannot be reversed.
- Osteophytes are evident as soon as 1 to 3 weeks after the rupture in some patients. This kind of joint disease is substantially more difficult for a large breed dog to bear though all dogs will ultimately show degenerative changes. Typically, after several weeks from the time of the acute injury, the dog may appear to get better but is not likely to become permanently normal.
- In one study, a group of dogs was studied for 6 months after cruciate rupture. At the end of 6 months, 85% of dogs under 30 lbs of body weight had regained near normal or improved function, while only 19% of dogs over 30 lbs had regained near normal function. Both groups of dogs required at least 4 months to show maximum improvement.