Your Dog’s Knees, Part 2: Diagnosis and Treatment of Common Knee Conditions

Jul 31, 2019

Your Dog’s Knees, Part 2: Diagnosis and Treatment of Common Knee Conditions

The two most common conditions to affect your dog’s knees are cranial cruciate ligament rupture and patellar luxation, which we addressed in our previous blog post. In this post, we will discuss how prompt diagnosis and treatment can have your dog back on her feet again in no time. 

Cranial Cruciate Rupture

In a dog’s knee, there are two cruciate ligaments that form an X-shaped connection in the knee joint between the distal (lower) femur and proximal (upper) tibia. The cranial, or front, ligament is the one that is most commonly torn, often causing acute lameness, with the patient unable to bear any weight (though some patients do not show acute injury symptoms and simply start limping or favoring the affected leg). An injury also common to human athletes, cranial cruciate rupture should be evaluated quickly for diagnosis and treatment.  

How Is Cranial Cruciate Rupture Diagnosed in Dogs?

If your dog demonstrates rear-leg lameness, she should be evaluated by your primary care veterinarian right away for possible cranial cruciate rupture. Tests commonly performed to identify a partial or complete rupture include:

  • Knee joint palpation to detect swelling
  • X-rays to look for joint swelling, arthritis, and other knee conditions, and to take measurements for surgical planning
  • Joint manipulations, including the cranial drawer and tibial compression tests, to detect abnormal knee motion indicative of cranial cruciate ligament rupture

How Is Cranial Cruciate Rupture Treated in Dogs?

If your family veterinarian diagnoses a cranial cruciate ligament rupture, she may refer your dog to DVSC’s orthopedic surgery department for treatment. After you consult with one of our orthopedic surgeons, we will develop a treatment plan that best fits your pet’s situation. If your pet has a torn CCL, surgical intervention is needed to correct the instability of the knee joint that the ruptured ligament has caused. Medical management of symptoms is possible, and can improve the quality of life, but delayed treatment of the rupture can cause irreversible arthritic damage in the knee joint.  

Medical treatment may include:

  • Anti-inflammatory medications
  • Activity restriction
  • Physical rehabilitation
  • Joint supplements
  • Weight loss, if needed

Surgical treatment methods for cranial cruciate ligament rupture include:

  • Tibial plateau leveling osteotomy (TPLO) — The top surface of the tibia is sloped backward in dogs, causing the tibia to thrust forward relative to the femur when a dog puts weight on its back leg. This contributes to joint instability and ligament degeneration. During a TPLO procedure, the top portion of the tibia is removed, rotated, and reattached with a stainless steel bone plate to flatten the natural tibial slope and eliminate the need for the cranial cruciate ligament’s stabilization. TPLO is the most common procedure performed at DVSC for cranial cruciate ligament rupture treatment, and is successful in dogs of all sizes. 
  • Tibial tuberosity advancement (TTA) — The proximal portion of the tibia is triangle-shaped, with the tibial tuberosity forming the point of the triangle. During a TTA procedure, the tibial tuberosity is partially cut, pulled away from the tibia, and held in place with a special bone plate. A stainless steel implant is placed in the gap that is created, and a bone graft is used to stimulate bone growth to fill in the gap. Advancing the tibial tuberosity adjusts the pull of the quadriceps muscle, and reduces tibial thrust to stabilize the knee. 
  • Lateral fabellar suture (LFS) — An LFS procedure involves placement of sterile suture material to mimic the action of the cranial cruciate ligament and encourage stabilizing scar tissue formation. LFS may be recommended for small dogs with cranial cruciate disease. 
  • Tightrope® procedure — A Tightrope® is a kevlar-like implant material surgically placed through drilled bone tunnels to stabilize the knee joint in place of the cranial cruciate ligament. A Tightrope® procedure can be performed on small animals and some larger dogs, though it is generally most successful in small patients. 
  • Bone anchor (BA) technique — This technique involves drilling a bone anchor into the bone near the knee joint and placing an orthopedic suture called FiberWire® across the joint to mimic the action of the cranial cruciate ligament and encourage stabilizing scar tissue formation. The BA technique is most successful for small dogs, but can sometimes be used in larger breeds. 

Patellar Luxation

The patella, or kneecap, sits in the femoral groove at the distal end of the femur. Dogs with patellar luxation have an abnormally shallow femoral groove, which causes the patella to deviate medially during flexion. Patellar luxation is graded in severity from grade I, where the patella can be manually moved out of the femoral groove but easily returns to normal position, to grade IV, where the patella is permanently luxated and cannot be manually replaced. 

Diagnosing Knee Conditions in Dogs

How Is Patellar Luxation Diagnosed in Dogs?

If your dog is experiencing rear-leg lameness, she should be evaluated by your primary care veterinarian. Evaluation for patellar luxation commonly includes palpation to confirm abnormal positioning of the patella and X-rays to evaluate the knee joint and screen for arthritis. 

How Is Patellar Luxation Treated in Dogs?

Patellar luxation treatment often includes a combination of several surgical procedures, including:

  • Femoral groove deepening — Deepening the femoral groove allows the patella to sit more deeply in the groove and prevents future luxation. 
  • Tibial tuberosity transposition — The patellar tendon, which helps hold the patella in place, attaches to the tibial tuberosity. Surgical relocation of this tendon’s attachment site to a more lateral position realigns the patella and keeps it in the femoral groove. 
  • Joint capsule modification — Soft tissues surrounding the knee joint are reconstructed to loosen the medial pull on the patella and tighten the lateral side. 

If your dog is suffering from a knee condition and your family veterinarian has referred you to a specialist, contact us