11/24/2025
Have you had a dog who experienced limping and you didn’t know where to turn? Pain management? Consultation with your primary veterinarian or a specialist?
The cranial cruciate ligament (CrCL) is one of the most important stabilizers of the knee joint (stifle). In humans, this ligament is termed Anterior Cruciate Ligament (ACL). A healthy CrCL prevents the forward movement (drawer) and internal rotation of the tibia (shin bone).
Rupture of the CrCL is the most common cause of rear leg lameness, pain, and the development of arthritis. Rupture involves a combination of various factors including aging of the ligament (degeneration), skeletal conformation, obesity, poor physical condition, and breed. Cranial cruciate ligament rupture is usually a subtle and slow degeneration over time, rather than sudden rupture to an otherwise healthy ligament. Partial CrCL rupture is common in dogs and almost always progresses to a complete rupture over time.
Cranial cruciate ligament disease can affect dogs of all ages, sizes, and breeds. Although this condition can affect cats, this is rare.
Dogs with early partial CrCL rupture can seem “normal” after a period of rest and medication(s). With progressive rupture, dogs will experience some of the following clinical signs:
• Lameness (limping) with varying degrees of severity (sometimes only noted after prolonged rest)
• Difficulty sitting and/or rising; sitting with the affected leg “out”
• Muscle atrophy as the leg is used less
• Decreased range of motion of the knee joint
• A “popping” or clicking noise that may indicate a meniscal tear
• Thickening of the knee joint (fibrosis of the joint capsule)
Diagnosis is often made on physical examination alone. However, in early partial ruptures, sedation may facilitate examination by allowing the leg muscles to relax and thus palpate subptle instability (cranial drawer). X-rays can be used to support the diagnosis of a CrCL rupture with signs of excessive joint fluid (effusion) and arthritis. These same x-rays are used in surgical planning.
Several treatment options are available for CrCL injury. Treatment options can be separated into surgical options versus non-surgical (conservative management). The best option for your pet will depend on factors such as size, age, skeletal conformation, degree of instability, and level of arthritis. Surgical treatment is typically the best option because it addresses the primary problem of instability at the knee joint. With proper stabilization, lameness will resolve and your pet can return to normal function.
Surgical options are either of the osteotomy (bone cut) technique or suture technique. The Tibial Plateau Leveling Osteotomy (TPLO) has become the gold standard for active dogs of all ages and sizes because of the consistent outcomes in even the most athletic patients. The cut in the bone (osteotomy) is stabilized with a bone plate and screws while the cut heals (bony union), which can take 6-8 weeks in most cases. Strict rest and confinement are required to prevent complications.
Lateral Fabellotibial Suture (aka Ex-cap suture or fishing line technique) is one of the first techniques developed to stabilize the dog knee joint. With this technique, a heavy suture/nylon line is placed outside the knee joint to provide temporary stability while the body lays down scar tissue (fibrosis) at the knee. This scar tissue provides permanent stability. If the suture/line breaks before sufficient scar tissue develops, residual instability will continue to cause chronic lameness and development of arthritis. Although this technique is often less costly than the TPLO, it may not be the best option for larger and younger patients, or small dogs with an excessive Tibial Plateau Angle (TPA). An excessive TPA of 35 degrees or more will put unnecessary stress on the suture line, risking premature failure.
These are immediate post-operative x-rays of a 10 year-old, 18 pound dog that underwent a TPLO for a complete CrCL rupture.
