The Cranial Cruciate Ligament (CCL)

The cranial cruciate ligament is one of four major ligaments in the canine stifle. It is responsible for maintaining stability of the stifle by preventing the tibia from excessive movement, hyperextension of the stifle, internal rotation and it also aids in proprioception (the animal’s awareness of placement of the limb). The CCL is the most common ligament injured in the canine patient, accounting for the majority of orthopedic conditions seen in the veterinary practice.

Diagnosing CCL Injuries

Typically, the patient with a suspected CCL injury will present a history with one or more of the following signs/symptoms¹:

• Difficulty rising from a sit
• Trouble jumping into the car
• Decreased activity level
• Lameness (limping) of variable severity
• Muscle atrophy (decreased muscle mass in the affected leg)
• Decreased range of motion of the knee joint
• A popping noise (which may indicate a meniscal tear)
• Swelling on the inside of the shin bone (fibrosis or scar tissue)
• Pain
• Unwillingness to play
• Stiffness

During examination, veterinarians may employ several diagnostics to confirm rupture of the ligament including palpation, radiographs and synovial fluid testing (to rule out other joint related diseases).

Treating the Fully Ruptured CCL

When a CCL has fully ruptured (or torn), surgical intervention is commonly recommended to correct the instability and to return function back to the joint. While no single surgical procedure has been established as the superior method, techniques that are often employed include Tibial Plateau Leveling Osteotomy (TPLO), Tibial Tuberosity Advancement (TTA), Tightrope and lateral suture. Typical surgery costs may range from $1,000 to $5,000, or more. Whether or not the patient undergoes surgery, there is a high probability that the arthritis will develop within the joint and there is a 40-60% chance the opposite CCL will rupture in the future.

The Challenges of Partially Torn CCLs

 1. Diagnosis

While the above mentioned diagnostics are usually sufficient in confirmation of a complete CCL rupture, partially torn CCL’s can be challenging to diagnose due to inconclusive palpation findings and presence of stability in the joint. For these patients, diagnosing the partially torn ligament may require additional diagnostic capabilities such as arthroscopy (or needle scope) or further investigation into the patient’s lameness history if no other diagnostics are available.

2. Treatment

For the completely torn CCL, surgical interventions are necessary to stabilize the joint and prevent further damage if possible. But what about the partially torn CCL?

Current treatment options geared towards the partial CCL tear are focused on pain management and limb stabilization. While both are needed for recovery and repair of the tissue, the repair of the cruciate ligament is limited by the vascularization of the tissue and the number of cells that are needed to repair the damage.

Although surgery can provide the stabilization needed for the joint, it is an invasive procedure not without some risks to the patient.  What if the stability of the joint is not yet compromised? If the joint still has some form of stability and the ligament is in the early stages of degeneration, can the joint be treated in a minimally invasive manner to prevent further injury and repair the tissue?

In one recently published study, these questions were investigated and the use of regenerative medicine for the treatment of partial CCL tears was examined.²

Regenerative Medicine for the Treatment of Partial CCL Tears

In this retrospective analysis, investigators reviewed the records of 36 client-owned canines that had a unilateral, partially torn CCL (defined as less than 50% tear in their CCL’s)  and were treated with a combination of stem cells (adipose or bone marrow derived) and platelet rich plasma in combination with rehabilitation therapy and a functional stifle brace. The study investigated the patients’ pressure index, collected pet owner surveys and performed 90 day follow up arthroscopic examinations on 13 out of the 36 original study patients.

Results of the study were promising with 10 out of the 13 patients having fully intact CCL’s visualized on 90 day follow up arthroscopy with neovascularization and normal fiber pattern. 3 out of the 13 patients had progressed to more than 50% tear or completely ruptured, in which case a TPLO was performed.  When owners were asked about their pets’ recoveries, all respondents believed their dog had excellent or very good quality of life and their dogs’ recovery was excellent or good.

Return of the Athlete?

This study not only looked at “weekend warriors” but also the high-level athlete. Seven (7)  of the dogs that were observed in this study were designated as performance dogs and at the conclusion of the study, 6/7 dogs had returned to sport. Of the six that returned to sport, four patients were back to competing at the same level and two were back to competing at a higher level.

What Conclusions Can We Draw from This Study?

Even with certain study limitations, the results from the available patients showed a promising possible alternative to treating an injury that may have otherwise resulted in a full rupture. From this data, one may hypothesize that if partial CCL injuries are detected early in their development and are treated with a combination approach of platelet rich plasma and stem cell therapy, there is a chance that the ligament could heal, negating the immediate need for surgical intervention. This could not only improve the patient’s quality of life, but also provide a minimally invasive therapeutic alternative.

While surgery will always have its place in CCL rupture recovery, perhaps it’s not the only tool in the toolbox available for small animal practitioners.

To be the first to know when new studies, education webinars, articles, and blog posts like these are published, make sure you sign up for our monthly newsletter: http://www.litecureinfo.com/CompanionWellnessReportOptIn

References:
1. Cranial Cruciate Ligament Disease, www.acvs.org/small-animal/cranial-cruciate-ligament-disease
2. Canapp SO Jr, Leasure CS, Cox C, Ibrahim V and Carr BJ (2016). Partial Cranial Cruciate Ligament Tears Treated with Stem Cell and Platelet-Rich Plasma Combination Therapy in 36 Dogs: A Retrospective Study. Front. Vet. Sci. 3:112. Doi:10.3389/fvets.2016.00112