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Cranial Cruciate Ligament rupture
<this document is under construction>

Cranial Cruciate Ligament rupture in a nutshell (quick summary)

What is the Cranial Cruciate Ligament?

Where is the Cranial Cruciate Ligament?
Where is the knee in a dog?
What is the stifle?

What is a torn ACL?
What is a torn (or ruptured) cruciate?

How did this happen?

How is it diagnosed?

What is a torn meniscus?

How is a meniscal tear treated?

What if my pet only has a partial tear?

Does my pet need surgery?

What if I elect conservative management?

My pet got better with conservative management. Why would you recommend surgery?

What about braces?

What about rehabilitation ("physical therapy")?

What does surgery involve?

Will my pet develop arthritis?

How can I minimize my pet's arthritis?

How can I make my pet most comfortable?

I don't want to put my pet through surgery.

What is best for my pet?

The Cranial Cruciate Ligament (CCL) is the dog -- or cat, or other quadruped/four-legged walking animal -- equivalent to the human ACL (Anterior Cruciate Ligament) tear. 

  • Similarly, a dog's caudal cruciate ligament is the equivalent of the human PCL (Posterior Cruciate Ligament) 
  • As dogs, etc. walk on four legs, they do not technically have an anterior aspect. Instead, the correct terminology is “cranial,” which means closer to the head or front of the body (and "caudal" means closer to the tail)
  • Nonetheless, since most people are more familiar with the term “ACL,” many veterinarians use that term when referring to CCL tears.
  • If your vet said your pet has an ACL, or an ACL tear, he or she is referring to a torn cranial cruciate ligament.
  • Cruciate means "X." The two cruciate ligaments form an "x," with the cranial ligament as the front part and crossing over from lateral to medial, and the caudal being behind and crossing over from medial to lateral.
  • Ligaments are supportive structures that connect one bone to another bone.
    • In the case of the cranial cruciate ligament, it is one of 5 ligaments that connects the femur (thigh bone) to the tibia (shin)
    • Ligaments are different than tendons, which connect muscle to bone.

Location, Location, Location

  • The cruciate ligaments connect the femur (thigh bone) to the tibia (shin bone).
  • The cruciate ligaments are on the inside of the joint known as the stifle in animals.
  • The stifle is the same as the knee in a person.
  • It is in the back leg.
  • It is the joint below the hip and above the ankle.
  • In horses and other hoof-stock, "knee" refers to the carpus (wrist joint), in the front leg. That is not true for dogs, cats, etc.

HOW?

Cranial Cruciate Ligament (CCL) ruptures are the most common orthopedic injury in dogs. A torn or ruptured "ACL" or "cruciate" means a torn CCL.

  • A CCL tear is the result of a single athletic event and/or a combination of multiple small injuries and stress over lifetime, perhaps exacerbated by weight, conformation (build, etc.)
  • This occurs in cats as well, but as it is much more common (or at least more commonly diagnosed) in dogs, most of this discussion will refer to dogs.
  • CCL tears are very painful initially.
    • Most pets become less painful with time and rest, but the ligament does not heal. 
      • Many owners and vets make the mistake of thinking that this improve means the pet is getting better and does not need surgery.
    • The instability remains, and arthritis gets worse with time and instability.
  • CCL tears are painful enough, but they are even worse when the meniscus is damaged.
  • CCL tears can be partial or complete.
    • Complete tears
      • Complete tears more easily diagnosed, as the instability is more obvious.
      • Complete tears are less likely to improve with time, and are highly likely to lead to meniscal tears.
    • Partial tears
      • Partial tears are often more difficult to diagnose, particularly if the pet is large, strong, and/or struggling, and/or if the veterinarian does not regularly perform cruciate surgery.
      • Partial tears usually do not heal.
        • In my experience, partial tears typically progress to complete tears.
        • With rest, the severe pain associated with a ligament tear dulls with time, but the instability remains.
        • The instability leads to inflammation (arthritis), which will progressively damage the cartilage and lead to long-term joint pain.
        • Surgery cannot correct/remove arthritis that is already present.
          • Surgery can eliminate instability.
          • Surgery can remove the pain associated with a torn ligament +/- torn mensicus and the associated instability.
        • Instability also increases the risk of tearing the meniscus.
      • Many vets and owners believe partial tears do not need surgery. I believe this is a mistake.
        • In my experience, partial cruciate tears are the ideal indication for surgery.
        • You catch the joint before a large amount of damage and arthritis has occurred.
        • In most cases of partial cruciate tears, the meniscus is intact. Pets with an intact meniscus usually have less pain and arthritis long-term.
        • Since the meniscus is intact, the joint can be stabilized by working outside the joint and not performing an arthrotomy (opening the joint). This leads to less pain in the immediate post-operative period, with less lameness and a more swift recovery. 
        • In my experience, partial tears typically progress to full tears, during which more arthritis develops, and there is a greater risk of tearing the meniscus. 

The meniscus

The meniscus is very important to the knee.
A torn meniscus is very painful and leads to more long-term pain and arthritis. 
It is bad, and you want to prevent this.

  • The meniscus is a semi-lunar cartilage that acts as a cushion and stabilizer between the femur (thigh bone) and tibia (shin).
  • There are two menisci in each knee, one medially (toward the middle) and one laterally.
    • The menisci are very important in
    • Cushioning the cartilage and bone
    • Providing stability
    • Maintaining joint hydration and lubrication
  • In dog's, meniscal tears almost exclusively occur following a tear of the cruciate ligament
    • The instability caused by a cruciate tear leads to shearing/rubbing and eventual tearing of the menisci.
    • Most commonly a tear of the caudal (back part of the) medial meniscus occurs.
  • Meniscal tears lead to 
    • Severe pain (it's like stepping on a rock in your shoe)
    • Increased instability
    • Direct cartilage rubbing
    • Friction and thermal necrosis (heat injury)
    • Progressive arthritis and cartilage breakdown 
  • Diagnosis of a meniscal tear
    • Typically severe pain that does not improve significantly with rest and/or pain medications
    • Often there is a "click" or "pop" when manipulated or when the pet walks.
    • Radiographs (x-rays) cannot image ("see" ) the meniscus unless it is mineralized/calcified, which is relatively uncommon.
    • A high-field MRI (magnetic resonance imaging) can diagnose a meniscal tear definitively pre-operatively
    • Most veterinary-owned MRIs are low field (0.2 - 0.3 Tesla) and cannot even "see" the meniscus.
    • A high-field MRI (1.5 - 3.0 Tesla or higher) is required to diagnose a meniscal tear
    • Obtaining a high-field MRI requires traveling to distant location such as the University of Florida and costs usually at least $1500 or more.
    • Since the meniscus is directly inspected during cruciate surgery in any case with a complete cruciate tear, most people choose to go directly to surgery and avoid the travel and additional expense.
  • Treatment of a torn meniscus
    • Surgery is required to alleviate the severe pain of a torn meniscus.
    • Meniscal repairs fail
      • Because of the way a dog's leg is built, they cannot wear an immobilizer brace like a person. As a result, we cannot protect the knee from micro-motion, and repairs of the meniscus (surgical or arthroscopic) fail, requiring removal.
    • Partial meniscectomy
      • The torn portion of the meniscus is removed.
      • This eliminates the severe pain of the tear.
      • The rest of the intact meniscus is preserved. 
      • Pets who have had a part of the meniscus removed are more prone to arthritis than a pet whose meniscus was intact and preserved. However, they are much less painful than a patient with a torn meniscus.
    • Conservative management leads to increased pain and arthritis both short and long term. This can be crippling, significantly diminishing a pet's quality of life. Some pets are euthanized due to severe arthritis.
    • Arthritis can be treated medically, but it worsens over time.

Medical management 

  • Most pets improve initially as the severe pain from a fresh tear fades into a dull ache.
    • Pets improve, but they don't get completely better.
      • They may improve from non-weight-bearing to perhaps 50-70% weight-bearing
      • Most owners do not perceive any lameness at this point
    • Blow out the other knee
      • The pet shifts weight over to their other leg, and most pets tear the cranial cruciate ligament in their other leg as well.
      • Pets can do well with 3 good legs, but when both back legs are affected, it is hard to get up and painful to move around.
    • As a result, the pets become less active.
      • Loss of muscle mass
      • Weight gain
      • This worsens the expression of arthritis, which leads to less activity
    • Downward spiral - worsening arthritis pain leads to less activity, which leads to worse arthritis pain, etc.
  • Arthritis pain can be treated, but it gets worse much more rapidly over time without surgical stabilization.
  • Cruciate tears do not heal
  • The instability remains and worsens over time
  • Severe arthritis develops at an early age
    • Diminished comfort and quality of life
    • Long-term pain
    • Increased medical expense of arthritis treatment
  • "Getting Old"
    • Owners often think a pet is just getting old
    • Pets are sometimes euthanized for arthritis that was largely preventable.

Diagnosis

Cranial drawer – like a drawer moving out of a dresser

How is it diagnosed?

What is a torn meniscus?

How is a meniscal tear treated?

What if my pet only has a partial tear?

Does my pet need surgery?

What if I elect conservative management?

My pet got better with conservative management. Why would you recommend surgery?

What about braces?

What about rehabilitation ("physical therapy")?

What does surgery involve?

Will my pet develop arthritis?

How can I minimize my pet's arthritis?

How can I make my pet most comfortable?

I don't want to put my pet through surgery.

What is best for my pet?

Options include:

  • Medical management: NSAIDs (non-steroidal anti-inflammatory drugs, such as Previcox, Metacam, or Rimadyl/Carprofen), Chondoprotective (cartilage protecting) medications (such as oral Dasuquin, or the even more effective injectible Adequan), +/- Tramadol (similar in action to a low-dose morphine-type drug)
    • Typically results in 50-60% of function long-term, highly predisposes pet to contralateral injury, which can be crippling and diminish a pet’s length and quality of life.
       
  • Rehabilitation (“physical therapy”)
  • Stem Cell therapy
  • Surgery
  • Discussed surgical treatments at length
  • Recommend Tibial Tuberosity Advancement (TTA)/Modified Maquet Technique >> original TTA >> TPLO >> extracapsular >> rehabilitation only
  • Ideally would perform surgery (and stem cell therapy), and then perform rehab, but rehab and medical therapy may be considered if surgery is not an option

Meniscus

  • 50% of dogs with a cranial cruciate rupture, particularly of a chronic nature, also have a tear of the medial meniscus
  • If the meniscus is torn, we remove the damaged portion of the meniscus.
  • If the meniscus is intact, we wish to preserve it, because the meniscus is important in slowing the progression of arthritis.
  • However, historically 5-10% of dogs with an intact meniscus may tear it at some point post-operatively, necessitating another surgery.
  • A meniscal release procedure can be performed to reduce (but not eliminate) the risk of such a tear, though this may increase the risk of arthritis over time.
  • Alternatively, the meniscus may be left intact, particularly in a young, healthy dog, to reduce the progression of arthritis over time. The TTA is intended to reduce the risk of meniscal tears.
  • Ultimately, it is the owner’s choice: If the meniscus is intact, would you prefer to:
    • Leave the meniscus intact to minimize arthritis, but accept the risk that further surgery may be necessary if the meniscus tears in the future.
    • Perform a meniscal release to reduce the risk of further surgery, but accept that arthritis may progress over time. This may be more desirable in an older pet.

Reviewed prognosis/risk of surgery:

  • MOST pets typically do very well, are weight-bearing on the operated limb within 24 hours post-operatively, and end up with 90-100% function long-term.
  • Pets will need to wear the E-Collar for 2 weeks and be restricted to leash walking until instructed otherwise (generally 8-12 weeks)
  • Approximately 5% chance of significant complications, which may include additional surgery
    • Breakdown of repair or bone fracture is unlikely, and usually results from inappropriate exercise restriction, allowing the pet to walk/run/play off the leash, not restricting to a crate or a small room, etc.
    • Infection is also unlikely, and usually results from failure to use the E-Collar at all times.
    • Life-threatening complications are very rare, but they exist, just as they do in people.
  • With bilateral/simultaneous surgery, however, risks of major complications may increase to closer to 25+%. For this reason, I recommend staging surgery by at least 4-8 weeks.

Options to maximize outcome (comfort, bone healing, and resistance to infection)

  • Stem Cells are precursor cell that can develop into almost any cell type in the body.
    • They are derived from your pet’s own adipose (fat) tissue and have benefits in
      • Maximizing rate and degree of soft tissue and bone healing
      • Decreasing inflammation
      • Decreasing pain – further promotes comfort by stimulating morphine receptor on the spine, much like a morphine epidural
      • Effects generally lasting closer to a year, with doses banked for lifetime therapy without further surgery.
      • Also benefits with many other diseases/problems. See www.vet-stem.com
    • They may be harvested for direct treatment, in which case they are also banked for future use for the life of your pet; or they be simply banked for future use at a reduced initial cost – this allows therapy in the future without a need for further surgery to harvest cells when your pet is older.
    • The allogeneic stem cell clinical trial (from young, robust donors) has completed its enrollment and no longer accepting new patients.
  • Platelet-rich Plasma – rich in growth factors to promote healing and decrease arthritis - benefits generally lasting a couple months.
  • Allograft – bone graft material can be packed into the surgery site to expedite the healing.
  • Rehabilitation ("Physical Therapy" - including laser, acupuncture, electrical muscle and nerve stimulation, massage, stretching, underwater treadmill, etc.) to maximize comfort, limb use, healing, long-term function.
  • While unrelated to the current problem, if your pet is undergoing anesthesia/surgery, particularly if the abdomen is being accessed, such as for stem cell therapy, you may wish to consider a prophylactic gastropexy to prevent gastric dilatation-volvulus (GDV; commonly known as “bloat”). Via a 4 cm incision behind the last rib, the stomach can be sutured/stitched/tacked to the body wall to prevent torsion of the stomach that can be life-threatening within hours.

Pre-operative diagnostics:

  • Recommend Complete Blood Count/Serum Chemistry in all patients and Chest radiographs (x-rays) – if over 5 years old or showing any clinical signs of heart, airway, or lung problems – to screen for other disease.
  • iStat/Chem-8 (limited serum chemistry) is minimum pre-op screening (as well as bilateral stifle (knee) and VD pelvis rads, which is included in surgery package. 
  • Discussed MRI as non-invasive imaging tool to confirm cruciate rupture and evaluate meniscus. MRI is often cost-prohibitive, and the presence of drawer sufficiently warrants surgery. 
  • Discussed additional costs for follow-up radiographs (perhaps 2-3 sets) +/- radiologist review +/- injectable sedation/anesthesia
  • Additional costs for additional hospitalization on fluids, IV meds, recheck bloodwork beyond first day.

Cranial Cruciate Ligament tears in a "nutshell" - a quick summary

Cranial Cruciate Ligament tears lead to pain and progressive develop of arthritis (and injury to the mensicus)

Pets can improve with rest, but don't get 100% better, and as a result, they shift weight over to their other back leg. Conservative management usually leads to cruciate injury in the other back leg, and eventually to tears of both cruciates, tears of both menisci, and progressive arthritis.

Many dogs become severely arthritic at a relatively young age, and they become less active, gain weight, lose muscle, and develop progressively less comfort and function; it is a downward spiral and can lead to crippling pain and poor quality of life (and often euthanasia) years before a pet's natural lifespan.

Treating the injury as early in the disease process as possible minimizes your pet's long-term arthritis and maximizes your pet's comfort and quality of life.

Please schedule an appointment with our board-certified surgeon, Dr. Jeff Christiansen at the clinic of your choice, to evaluate for and treat your pet's cruciate injury to improve your pet or patient's length and quality of life.

If you have additional questions, please feel free to e-mail Dr. Christiansen directly.