A Guide to Canine Stifle Anatomy and Treatment Options

The canine stifle is the equivalent of the human knee, responsible for bearing weight and facilitating movement. It's a complex joint that can be prone to injury.

The stifle joint is made up of the femur, patella, and tibia, with the patella acting as a shock absorber and the cruciate ligaments providing stability. This intricate structure is susceptible to damage from overuse or trauma.

Canine stifle injuries often occur due to repetitive stress, such as jumping or running, which can cause the joint to degenerate over time. This can lead to conditions like cranial cruciate ligament (CCL) rupture, a common issue in dogs.

Treatment options for canine stifle injuries include surgical repair or replacement of the CCL, as well as physical therapy and pain management to manage symptoms and promote healing.

Trauma is a common reason for ACL injuries in humans, but it's relatively rare in dogs, where CCLD is often caused by a combination of factors, including aging of the ligament, obesity, and poor physical condition.

Most dogs that develop CCLD in one knee will likely develop a similar problem in the other knee at some point in the future.

Partial tearing of the CCL is common in dogs and frequently progresses to a full tear over time.

Certain breeds, such as Rottweiler, Newfoundland, and Labrador Retriever, are more prone to CCLD, while breeds like Greyhound and Dachshund are less often affected.

Female and neutered dogs are at a higher risk of developing CCLD, although the exact reason for this is unknown.

Curious to learn more? Check out: Male Dogs Anatomy

Trauma is a common cause of ACL injuries in humans, but it's relatively rare in dogs.

Most CCLD cases in dogs are caused by a combination of factors, including aging of the ligament, obesity, poor physical condition, conformation, and breed.

Aging of the ligament is a significant contributor to CCLD, and it's a slow process that can take months or even years.

Obesity is another major risk factor, as it puts extra stress on the ligament.

Related reading: Canine External Ear Anatomy

Poor physical condition and conformation can also increase the likelihood of CCLD.

In fact, at least half of dogs that develop CCLD in one knee will likely develop it in the other knee at some point in the future.

Partial tearing of the CCL is common in dogs and often progresses to a full tear over time.

Cruciate disease affects dogs of all sizes and ages, but rarely cats. Certain breeds are more prone to CCLD, such as Rottweiler, Newfoundland, Staffordshire Terrier, Mastiff, Akita, Saint Bernard, Chesapeake Bay Retriever, and Labrador Retriever.

Female and neutered dogs are at a greater risk of developing CCLD, although the exact reason is unknown. The benefits of neutering may outweigh this increased risk.

Newfoundlands have been shown to have a genetic mode of inheritance for CCLD.

Dogs with CCLD often don't show severe lameness initially, especially if both knees are affected.

You may notice your dog sitting with their legs out to the side instead of sitting square.

Difficulty rising, trouble jumping into the car, and a decreased activity level can also be symptoms.

Muscle atrophy, decreased range of motion, and a popping noise (which may indicate a meniscal tear) are other signs.

Swelling on the inside of the shin bone, fibrosis, or scar tissue can also be present.

Dogs may shift their weight away from the damaged leg when standing, but the lameness is less obvious during walking.

With a complete rupture or meniscal damage, your dog may become non-weight bearing lame and hop on three legs.

This change in lameness can happen suddenly, usually without major trauma.

Dogs with chronic CCLD often show symptoms associated with arthritis, such as decreased activity, stiffness, and pain.

Recommended read: Symptoms of Canine Lupus

Diagnosing a complete tear of the CCL is relatively straightforward, but early partial tears can be trickier to identify.

Observation of your pet's gait and palpation of the knee are crucial in diagnosing a CCL issue.

A combination of these methods, along with radiographs (X-rays), is usually sufficient to confirm a complete tear, but advanced imaging like MRI or surgical exploration may be needed for early partial tears.

X-rays are taken to confirm joint effusion, arthritis, and to rule out other conditions, and specific X-rays are required for certain treatments like TPLO and TTA.

Diagnosing a complete tear of the CCL is easily accomplished by a combination of observation of your pet's gait, palpation of the knee, and radiographs (X-rays).

X-rays are usually taken to confirm the presence of joint effusion, which indicates a problem within the joint, and to rule out concurrent disease conditions such as bone cancer.

The "cranial drawer test" and the "tibial thrust test" are specific palpation techniques used by veterinarians to confirm abnormal motion in the knee and hence a rupture of the CCL.

X-rays do not show the status of the CCL or the meniscus because those structures cannot be seen on X-rays.

A surgeon must evaluate both the meniscus and the cruciate ligament when performing a surgical repair, which can be done via an arthrotomy or with the use of a minimally-invasive camera (arthroscope).

Recommended read: Canine Brucellosis Test

Differential Diagnoses are crucial in determining the best treatment for your pet. CCLD is one of the most common reasons for persistent hind limb lameness in dogs.

Hip dysplasia is another common condition that can cause pain and lameness in the rear limbs of dogs. It's a genetic condition that affects the hip joint.

Joint sprains or muscle strains can also cause lameness, especially if your dog has been active or has suffered an injury. They can be acute or chronic, depending on the severity of the strain.

Knee cap displacement is a condition that can occur in combination with CCLD. It's a misalignment of the kneecap that can cause pain and discomfort.

Neurologic disease, such as a ruptured disc, can also cause lameness in the rear limbs of dogs. This type of injury can be severe and requires immediate veterinary attention.

Bone or soft tissue cancer can cause lameness and other symptoms, such as weight loss and lethargy. It's a serious condition that requires prompt treatment.

Discover more: Canine Cancer Treatment

Fractures can also cause lameness, especially if they're left untreated. They can be caused by trauma or osteoporosis.

Joint dislocations, or luxations, can cause lameness and pain in the rear limbs of dogs. They can be caused by trauma or a sudden twisting motion.

Tendon rupture, specifically the Achilles tendon, can cause lameness and pain in the rear limbs of dogs. It's a serious condition that requires prompt treatment.

Panosteitis is an inflammatory bone disease that's seen mainly in young, large breed dogs. It can cause lameness and pain in the rear limbs.

Osteochondrosis is a cartilage disease that can cause lameness and pain in the rear limbs of dogs. It's a condition that affects the joints and can be caused by genetics or trauma.

Expand your knowledge: Canine Lupus Disease

Tibial Plateau Leveling Osteotomy (TPLO) is a surgical technique used to stabilize the canine stifle joint. This procedure involves making a circular cut in the tibial plateau and rotating the contact surface of this bone.

The goal of TPLO is to render the knee relatively stable, independent of the CCL. This is achieved by changing the biomechanics of the knee joint. The tibial plateau is rotated until it attains a relatively level orientation, putting it at approximately 90 degrees to the attachment of the quadriceps muscles.

The TPLO technique is particularly beneficial for young, large breed dogs. It offers a superior outcome compared to traditional suture techniques, with better limb function and less progression of arthritis. The technique is often preferred by surgeons for large, active dogs.

The TPLO procedure requires a bone cut, which needs to be stabilized by a bridging bone plate and screws. The bone plate and screws are not needed once the bone has healed, but are seldom removed unless there is an associated problem.

Osteotomy techniques are a common approach for repairing the canine stifle joint, requiring a bone cut to change the way the quadriceps muscles act on the top of the shin bone.

Tibial tuberosity advancement (TTA) and tibial plateau leveling osteotomy (TPLO) are two osteotomy techniques that can be used to achieve stability without replacing the CCL itself, but by changing the biomechanics of the knee joint.

The TPLO technique is generally preferred by surgeons for large, active dogs, as it provides a reliable and effective way to restore joint stability.

A medial parapatellar arthrotomy is performed routinely during surgical procedures to evaluate the cranial and caudal cruciate ligaments, medial and lateral menisci, and joint cartilage.

The surgeon must take care to protect the caudal cruciate ligament from inadvertent laceration during the procedure, and suction and headlight illumination are essential for visualization.

Arthrotomy and meniscal procedures are crucial steps in surgical treatment for CCLD.

A medial parapatellar arthrotomy is performed routinely to evaluate the cranial and caudal cruciate ligaments, medial and lateral menisci, long digital extensor tendon, synovial lining, and joint cartilage.

The cranial cruciate ligament is débrided as appropriate. Placing a small Hohmann retractor between the caudal cruciate ligament and the tibial plateau facilitates visualization of the menisci while protecting the caudal cruciate ligament from inadvertent laceration.

Medial meniscal pathology is often present and can vary from partial-thickness tearing to a full-thickness bucket-handle tear to a severe crushing injury.

The surgeon should excise the pathologic segment of the medial meniscus, using caution to protect the caudal cruciate ligament in the process. Suction is essential, and headlight illumination is helpful.

If the meniscus is intact, a medial meniscal release can be performed because it has been theorized to decrease the incidence of delayed meniscal injury.

Osteotomy techniques are a type of surgical treatment for CCLD that change the way the quadriceps muscles act on the tibial plateau.

These techniques don't replace the CCL itself, but rather alter the biomechanics of the knee joint to achieve stability. Many surgeons prefer osteotomy techniques for large, active dogs.

There are two main osteotomy techniques: tibial tuberosity advancement (TTA) and tibial plateau leveling osteotomy (TPLO). Both techniques aim to stabilize the knee by changing the orientation of the tibial plateau.

In a TTA, the tibial tuberosity is advanced forward to orient the attachment of the quadriceps muscles at approximately 90 degrees to the tibial plateau. This technique requires a linear cut along the front of the shin bone.

The TPLO involves making a circular cut in the tibial plateau and rotating the contact surface until it's at approximately 90 degrees to the attachment of the quadriceps muscles. This orientation renders the knee relatively stable, independent of the CCL.

Both TTA and TPLO require the use of a bridging bone plate and screws to stabilize the cut in the bone. The bone plate and screws are usually left in place until the bone has healed.

The choice between TTA and TPLO depends on various factors, including the dog's anatomy, the surgeon's preference, and any concurrent problems.

See what others are reading: Canine Knee Anatomy

Suture techniques are a type of surgical treatment for CCLD that don't involve cutting into the joint itself.

Intra-articular suture techniques, which involve placing sutures within the joint, have not been successful in dogs due to differences in anatomy and disease process.

Extra-articular suture techniques, on the other hand, are performed outside the joint and are currently the most commonly used method in dogs.

The most commonly performed extra-articular technique is called extra-capsular suture stabilization.

This technique involves placing a strong suture material just outside the knee joint to mimic the CCL and stabilize the joint.

The suture is usually placed along a similar orientation to the original cruciate ligament, and its purpose is to stabilize the knee joint until organized scar tissue can form.

Suture failure tends to be more common in larger, active dogs, so many surgeons reserve this technique for small breeds, older, and/or inactive dogs.

The main advantages of this technique include the lower cost and the lack of a bone cut, which means that complications associated with the bone cut are not seen with this technique.

Post-Surgical Care is crucial for a successful recovery after a canine stifle surgery. Proper postoperative care is critical to prevent complications and ensure a smooth healing process.

Leash walking for a minimum of eight weeks is recommended to avoid putting excessive stress on the surgical repair. No running, jumping, rough-housing, or off-leash activity should be allowed during this time.

Physical therapy can speed up recovery and improve final outcomes, regardless of the surgical technique used. A rehabilitation regime that includes passive range of motion, balance exercises, and controlled walks on leash can be beneficial.

Aftercare is crucial to the success of your surgery. Premature, uncontrolled, or excessive activity can risk complete or partial failure of the surgical repair.

Leash walking is the only acceptable activity for the first eight weeks, and it's essential to stick to this rule. No running, jumping, rough-housing, or off-leash activity is allowed during this period.

Physical therapy is a game-changer for post-surgical recovery. Multiple studies have shown that it speeds up recovery and improves the final outcome, regardless of the chosen surgical technique.

Your rehabilitation should start immediately after surgery, and it's usually a regime of passive range of motion, balance exercises, and controlled walks on leash.

The prognosis for dogs after surgical repair of CCLD is good, with improvement reported in 85-90% of cases.

Arthritis will still progress, but at a slower rate when surgery is performed. Medical management of arthritis is recommended for any dog with CCLD, regardless of the surgical technique used.

Early surgical repair is advised by most surgeons to minimize the development of arthritis.

The canine stifle anatomy is made up of several key components. The stifle joint is formed by the femur, patella, and tibia bones.

The femur, or thighbone, is the longest bone in the dog's leg and bears the majority of the dog's weight. It's a sturdy bone that plays a crucial role in supporting the dog's body.

The patella, or kneecap, is a small, triangular bone that sits at the front of the stifle joint. It helps to protect the joint and facilitate movement.

The tibia, or shinbone, is the second longest bone in the dog's leg and connects the stifle joint to the hock joint.

Take a look at this: Canine Rear Leg Anatomy

The patellar ligament is a crucial component of the knee joint, connecting the quadriceps femoris muscle to the tibial tuberosity. It's a strong and vital part of the knee's anatomy.

The patellar ligament originates from the tendon of the quadriceps femoris muscle, specifically the portion that courses between the patella and the tibial tuberosity. This tendon is quite impressive, considering the patella is the largest sesamoid bone in the body.

The patellar ligament plays a key role in knee movement, allowing for flexion and extension of the knee joint. The collateral and cruciate ligaments, which are often referred to as femorotibial ligaments, work together with the patellar ligament to provide stability to the knee joint.

Additional reading: Canine Anatomy Muscles

The lateral collateral ligament plays a crucial role in limiting the rotation of the tibia. It extends from the lateral epicondyle of the femur to the head of the fibula, with some fibers attaching to the lateral condyle of the tibia.

Intriguing read: Canine Tibia Anatomy

This ligament courses over the tendon of origin of the popliteus muscle, which arises from the lateral femoral condyle. The lateral collateral ligament does not have any distinct attachments to the lateral meniscus.

The collateral ligaments limit the rotation of the tibia when the stifle is extended, and the lateral collateral ligament is particularly taut in this position. It prevents the tibia from rotating medially at the stifle, which would cause varus deviation of the stifle.

By palpating the stifle, you can check the integrity of the collateral ligaments by attempting to cause varus and valgus motion of the tibia.

The femorotibial joint is a crucial part of the stifle, allowing for flexion and extension of the limb. It's an articulation between the medial and lateral femoral and tibial condyles.

The femoral and tibial condyles don't fit together perfectly, which can make the joint prone to certain issues. This is where the fibrocartilaginous menisci come in, improving the congruency of the joint.

The four femorotibial ligaments associated with this joint are the medial and lateral collateral ligaments of the stifle, as well as the cranial and caudal cruciate ligaments.

The medial meniscus is a C-shaped fibrocartilaginous disc located between the medial femoral condyle and the medial tibial condyle.

It plays a crucial role in stabilizing the joint by deepening the articular surfaces of the tibial plateau, creating a "better fit" between the femoral and tibial condyles.

The medial meniscus is thicker at its peripheral portion than its central portion, and it develops from the fibrous layer of the joint capsule.

It's tightly fused to the medial collateral ligament, a relationship not observed between the lateral meniscus and lateral collateral ligament.

The medial meniscus is attached to the tibia by a cranial and caudal meniscotibial ligament, but it doesn't have an attachment to the femur.

This unique anatomy makes the medial meniscus susceptible to damage, particularly when the joint is unstable due to cruciate ligament injury.

It's essential to note that the medial meniscus is often affected in cases of joint instability, and veterinarians use specific palpation techniques, such as the "cranial drawer test" and "tibial thrust test", to confirm a problem with the CCL and associated meniscal pathology.

Take a look at this: Canine Parvovirus Test