The cranial cruciate ligament (CrCL) in dogs is similar to the anterior cruciate ligament (ACL) in humans. This cruciate ligament within the knee joint (stifle joint) stabilizes the joint during movement by preventing the tibia from sliding forward relative to the femur. It also prevents hyperextension of the knee and, to a lesser extent, internal rotation of the tibia. Rupture or tearing of the CrCL is a common orthopedic issue in dogs, occurring due to acute trauma or, more frequently, chronic degeneration.

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SYMPTOMS

Lameness: This can manifest as a sudden onset of severe lameness in the affected leg of a previously unaffected dog or as chronic, non-resolving low-grade lameness, which may temporarily improve but usually returns.
Swelling: Noticeable swelling around the knee joint.
Pain: The dog may show signs of pain, such as reluctance to bear weight on the leg, yelping, changes in behavior, or decreased willingness to be active.

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CAUSES

Acute Trauma: Sudden injuries from activities like running, jumping, or quick turns can cause an acute rupture. 
Chronic Degeneration: This is the primary cause of CrCL rupture in dogs, making it more of a condition than an acute injury. While it may seem like a traumatic event triggered the rupture, in most cases, there was already an ongoing degenerative process in the ligament, making it more prone to rupture during activity. 

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DIAGNOSIS​

A thorough physical and orthopedic examination is the primary tool for diagnosing CrCL rupture in dogs. Key examination findings include:

• Lameness in the affected limb(s)

• Palpable effusion (increased joint fluid)

• Palpable accumulation of peri-articular fibrosis on the inner aspect of the knee (medial buttress)

• Pain on knee extension

• Palpable instability, including cranial drawer instability and cranial tibial thrust instability

In many cases, palpable instability clearly indicates a ruptured CrCL. In cases of partial rupture, the knee may feel stable, but other examination findings are typically present.

Surgical treatment is the most common recommendation for this condition. Although the cause of the instability is typically different from that in humans, the result is similar: instability, pain, and progressing arthritic and fibrotic changes. The role of any surgery is to resolve the instability in the knee during active weight bearing.

 

POST SURGERY CARE

After surgery, patients will need to restrict their activity levels to prevent complications during the healing process. This requires strict kennel confinement. Patients should not be allowed to run, jump, play, have free range of the house or have ANY off-leash activity. Patient should also not be allowed to go up or down stairs. Patient should be out of the confined area only to go outside on a leash to urinate and defecate, after which they should be returned to the confined area. They may need additional support from a sling placed under the abdomen to provide support when walking over potentially slick surfaces. Failure to follow activity restriction instructions may result in complications and the need for a second surgery.

Follow-up visits with the surgeon are essential to assess recovery progress and perform X-rays (approximately 12 weeks post-surgery) to evaluate the healing of the osteotomy site. Based on these assessments, recommendations for future activity levels will be provided.

Full recovery time varies between patients, typically taking several months. Most dogs return to near-normal function within 4-6 months. TPLO has a high success rate, with the goal of surgery being to enable the patient to return to their optimal activity level for their stage of life. In the vast majority of cases, this goal is achieved.