The cranial cruciate ligament is one of the most important stabilizers inside the knee and is located in the middle of the back leg.
The CCL is known as the anterior cruciate ligament in humans (ACL). The meniscus is a cartilage-like structure located between the shin and the thigh bone.
It performs numerous important functions in the joint, including impact resistance, proprioception, and load bearing, and is oft-injured when the CCL is injured.
This problem develops much more complexly in dogs than in humans. Furthermore, dogs experience varying degrees of rupture (partial, complete).
As a result, the condition is more commonly referred to as “cranial cruciate disease” (CCLD) than “cranial cruciate ligament rupture” (CCLR).
Let’s dig deeper into the complexity of the CL anatomy and its injuries.
What is the Cruciate Ligament in Dogs?
Cruciate means “to cross over” or “to form a cross.” The cruciate ligaments are two bands of fibrous tissue that run along the inside of each stifle (knee) joint.
They connect the femur and tibia (the bones both above and below the knee joint) to form a stable, hinged joint.
One ligament runs from inside to outside of the knee joint, while the other runs from outside to inside, passing over each other in the middle.
The ligaments are known as the caudal and cranial CL in dogs and cats. The most common knee injury in dogs is a cranial cruciate ligament rupture or tear.
How Does a Cruciate Ligament Injury Occur?
The knee joint is a hinge joint based on its anatomy. Since there are no interconnected bones in the joint, it is relatively unstable.
It is instead held together by several tendons, including the cruciate ligaments, which enable it to move back and forth like a joint but limit its side-to-side motion.
Trauma and degenerative changes of the ligaments within the joint are the two most common causes of cranial tendon rupture.
A twisting injury to the knee joint causes an acute or traumatic ligamentous rupture. This usually happens once the dog (or athlete) is running and abruptly changes direction.
The majority of the body weight is placed on the knee joint, putting excessive rotational and lopping forces on the cruciate ligaments.
The anterior or cranial (front) ligament is generally injured. When cruciate ligament tears occur, the knee joint becomes unstable, resulting in lameness.
A more chronic form of cruciate damage arises as a result of increasing ligament weakness caused by recurrent trauma or arthritic illness.
Initially, the ligament is strained or partially ripped, resulting in only minor and occasional lameness. The problem worsens with continuing usage of the joint until a full rupture occurs.
Obese dogs tend to be more likely to suffer cruciate ligament tears. In these dogs, the damage may occur as a result of minor knee trauma, such as tripping over a rock while walking.
Dogs who have other knee issues, such as a luxating patella, are more likely to rupture their cruciate ligaments.
Dogs who rupture one cranial ligament are more likely to tear the second knee’s cranial cruciate ligament.
Symptoms and Sign of Cranial Cruciate Ligament Disease
As mentioned before, progressive degradation of the CCL in dogs is frequent, ranging from very minor partial tearing to a full rip in the latter stages of the disease.
Because of this progression, you may not first notice acute lameness, particularly if both knees are affected.
One indication is that dogs will no longer sit “square,” but will instead put their leg(s) out to the sides when they sit.
You may also notice that your dog is having difficulties rising, leaping into the car, and has a lower activity level. Other symptoms include muscle atrophy (muscle loss in the affected leg) and decreased range of motion.
A popping noise (which may suggest a meniscal rupture), and swelling on the interior of the shin bone could also appear.
Many dogs will shift their body aside from the injured leg when standing, but the lameness is less noticeable when running, especially with a partial cranial cruciate ligament injury. Your dog may become non-weight bearing lame and hop on three legs if a partially injured ligament ruptures entirely if the meniscus is ruptured.
This change in lameness can occur unexpectedly and without substantial trauma (a minor traumatic event may cause the partially torn ligament to rupture completely).
Dogs with chronic (late stage) CCLD typically exhibit arthritis-like signs (decreased activity, stiffness, knee pain, unwillingness to play, etc.).
Risk Factors for Cruciate Ligament Injury
Poor physical health and obesity are risk factors for the development of cranial cruciate ligament injury. Pet owners can impact both of these aspects.
Regular exercise and minimizing frequent excessive activity by normally inactive dogs (“weekend warrior syndrome”) is recommended to achieve a decent fitness level.
Physical activity will also aid in the prevention of obesity, as cruciate ligament rupture is more common in dogs with excessive body weight.
Giant and small breed animals with medial patellar luxations (MPLs) are the most commonly affected, but bigger, mixed breed, and feline canines are also affected.
CCL rip is more common in specific breeds, such as:
- Labrador Retriever
- Akita
- Chesapeake Bay Retriever
- Saint Bernard
- Newfoundland
- Neapolitan Mastiff
- Staffordshire Bull Terrier (SBT)
- Rottweiler
Some breeds are far more susceptible to ruptured cruciate ligaments than others. Most clients are in denial about their pets’ impacted knees, and even more so when pain is not yet evident.
Middle-aged to older pets are more likely to be affected, though vets have admitted pets as young as 8 months old with acute cruciate ligament injuries.
Diagnosis of Ruptured Cruciate Ligament
In the beginning, the vet will ask you a lot of questions that may seem unnecessary at the moment but will help them with the diagnosis.
They will also make a detailed physical examination of every body part, especially on the knee, where the pain was located.
Diagnosis of complete cruciate ligament tears is simple by using a combination of gait analysis, knee palpation, and radiographs (X-rays).
However, early partial tears are more complicated and may necessitate advanced imaging such as MRI or surgical exploration to examine the ligament. X-rays are commonly used to confirm the presence of joint effusion (fluid accumulation in the joint indicating a problem within the joint).
This test can also detect the extent of arthritis, aid in surgical planning, and rule out parallel disease conditions such as bone cancer.
Specific X-rays are required for certain treatments, and the doctor may need to redo radiographs of the knee even if your vet has already taken some.
The “cranial drawer test” and the “tibial thrust test” are specific palpation techniques used by veterinarians to confirm a ruptured cruciate ligament.
These tests confirm abnormal motion in the knee and thus a rupture of the CCL. Because X-rays cannot see the CCL or the meniscus, they cannot show their status (i.e. intact or damaged).
As a result, when performing the chosen surgical repair, the surgeon must evaluate both of these formations (meniscus and cruciate ligament).
Treatment Options for Cruciate Ligament Rupture
Although rest and medication can help, surgery to repair a ruptured cruciate ligament is usually recommended. The many surgical treatment options are explained in the following text.
Surgical treatment
Extracapsular Repair with Cruciate Surgery
A strong suture is used to secure the femur and tibia in this method, effectively replacing the role of the torn cruciate ligament.
The suture supports the knee joint while scar tissue forms and the muscles supporting the knee strengthen. The suture will eventually loosen or break. It must remain intact for eight to twelve weeks for healing to occur.
This is a simple and quick procedure with high success rates, especially in smaller dogs. It costs less than other methods. Long-term success varies, and smaller dogs may fare better.
Tibial Plateau Leveling Osteotomy (TPLO)
The tibial plateau leveling osteotomy is another surgical option (TPLO) for cruciate rupture. This is a more difficult process for veterinary surgeons, and it necessitates the use of specialized surgical equipment and training.
The tibial plateau leveling osteotomy TPLO modifies the biomechanics of the lower leg knee joint, allowing it to work normally in the absence of a cruciate ligament.
The tibia is completely cut through the top (the tibial plateau). To change the angle of the bone, the tibial plateau is rotated.
To repair the cut bone, a metal plate is affixed. The tibia heals over a period of months.
Partial improvement can be seen in a matter of days, but full recovery will take months, so cage rest is crucial. The long-term prognosis is generally favorable, and re-injury is unusual.
The long-term prognosis is generally favorable, and re-injury is uncommon. If no problems arise, the plate does not need to be removed.
The TPLO procedure is far more costly than traditional surgery of cruciate rupture.
Tibial Tuberosity Advancement tta
Tibial tuberosity advancement is a third surgical technique (TTA) for the ruptured cranial cruciate ligament.
The specifics of this procedure differ slightly from those of a TPLO, but it still involves cutting the tibia and implanting metal implants.
According to some surgeons, the TTA is a less invasive procedure than the TPLO. TTA may also be faster to recover than TPLO, though some specialists see little difference.
The anatomy and lifestyle of the dog are also important considerations. The TTA is similar in price to the TPLO.
Non-Surgical Treatment
Rest and non-inflammatory drugs
The lameness caused by CCLD usually wanes and improves significantly with pain medication administration.
This treatment may eliminate hind limb lameness in small dogs and with partial tears, but in larger dogs, some degree of lameness usually remains after cruciate rupture.
Attempts to resume normal activity levels are frequently hampered by the evolution of arthritis. Because the injured knee does not remain stable, the combination of pain meds and rest is not a treatment in and of itself.
While this treatment is not generally recommended, it may be appropriate for some dogs due to a combination of their small size, inactive lifestyle, other parallel injuries, or financial costs.
Rehabilitation
There is plenty of evidence that rehabilitation therapy provided by a trained recovery practitioner can help and speed up recovery from surgery.
There is, however, little evidence that this is a stable and accurate alternative to surgical intervention for the majority of dogs.
Concurrent injuries or illnesses, advanced age, patient size, and budget restrictions may occasionally make this an appealing alternative option.
KNEE BRACING
Because custom knee bracing is new in canine orthopedics, there is little scientific evidence available for its efficiency in cranial cruciate rupture.
Bracing is only a temporary solution, making it unsuitable for young, active animals.
Pets that weigh less than 22 lbs have a chance of healing the ruptured ligament with physical therapy and remain normal limb function.
Dogs that weigh over 22lbs require surgical management with the most commonly performed technique, like tibial tuberosity advancement TTA.
This is a consistent and predictable alternative where organized scar tissue is avoided using ligament replacement techniques or lateral fabellar suture stabilization.
Prognosis
After surgery, the prognosis is good, with an 85 to 90 probability of returning to normal activity levels.
Multiple steps are involved in post-surgical medical management for your dog’s recovery period.
It is beneficial to understand that smaller dogs (weighing less than 25-30 pounds) may fare much better than larger dogs.
Medical therapy entails the following steps:
- Several weeks in a cage
- Only take short, calm leash walks for toilet breaks
- Sit-to-stand workouts
- Swimming and/or underwater treadmill therapy
- Oral anti-inflammatory drugs and vitamins approved by veterinarians – to support joint health
The affected knee joint in these dogs may develop osteoarthritis. Furthermore, dogs suffering from this injury have a 40 to 50% chance of pulling the ligament in their other knee joint.
FAQ:
Conclusion
The cruciate ligaments are located on the back side of the knee joint and help with impact resistance and leg movement in dogs.
They can be ripped or dislocated due to two main reasons – degeneration, or physical pressure. Many treatment options exist, but surgical repair is preferred, especially in dogs weighing over 22lbs.
If you suspect that your pet has experienced this type of injury, you should visit your vet for further investigation and therapy.
Related topic: Swollen lymph nodes in dogs (not cancer)
*photo by tonodiaz – depositphotos