The Dog Owner's Guide to Torn Knee Ligaments

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A torn cruciate ligament, also called ACL or CCL, is very painful! Painful for your dog, and also painful for you to watch your dog suffer every time he takes a step.

Torn knee ligaments are often called ruptured cranial cruciate ligaments.  Other names you might hear for a cranial cruciate ligament injury include:

  • Torn ACL in dogs
  • Dog cruciate ligament tear
  • Canine torn ligament
  • Cranial cruciate ligament rupture
  • CCL disease

The cranial cruciate ligament connects the bone above the knee (tibia) to the bone below the knee (femur). The cranial cruciate ligament (CCL) keeps the tibia in place and stabilizes the knee joint.

The #1 symptom of torn knee ligaments in dogs is hind leg lameness. 

The main thing you need to know as a pet owner is: A torn cruciate ligament in your dog's stifle needs veterinary attention. If your dog is limping or not using one or both rear legs, see your veterinarian immediately.

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Risk Factors for Cranial Cruciate Ligament Injury in Dogs

There are several risk factors involved in a canine cruciate ligament injury.

First, let's review the typical events associated with dog ligament damage.

The canine cruciate ligament (CCL) is a thick fibrous band of connective tissue. The CCL stabilizes the knee much like a bungee cord.

The CCL stabilizes the knee by:

  • Preventing the tibia from sliding forward as it connects to the femur
  • Preventing tibial rotation
  • Preventing knee hyperextension

In cranial CCL disease, the ligament itself gradually degenerates. Professionals still have not figured out exactly why.

A good analogy of a cruciate ligament tear is the scenario of a rope left outside exposed to the weather. Over time, the rope weakens as individual fibers become weak, frayed, and damaged. 

Dog cruciate tears are pretty much opposite in etiology to human cruciate tears. In people, ACL tear pathology is usually the result of direct trauma, much like a football injury. The difference is a very important concept to remember.

Progressive deterioration of a dog’s knee ligament leads to:

  • Inflammation of the stifle joint
  • Partial rupture, progressive rupturing
  • Complete rupture
  • Secondary diseases such as progressive osteoarthritis and cartilage damage

Dogs with early ligament deterioration may have little or no palpable instability. But, they often display lameness and swelling of the stifle joint. Dogs in early ligament deterioration may improve with minimal treatment, such as cage rest and leash walks. However, if the deterioration continues, the end result is complete ligament rupture.

Complete cranial cruciate ligament ruptures produce marked instability of the stifle joint. Instability results in severe lameness and progressive degenerative changes such as:

  • Arthritis
  • Joint capsular thickening
  • Cartilage degeneration

Why is this information important to you?

Because, as ligament tears progress, dogs show varying signs and degrees of lameness. Some dogs only limp occasionally, while other dogs limp all the time. Some dogs recover without medical intervention while others have to undergo costly surgery. Sometimes, recovery may simply imply the dog’s ability to adapt to the injury.

We all know dogs are amazing in their ability to adapt to pain and injury. Though sometimes, wear and tear accumulate with painful and debilitating results. Also, it is important to remember that lameness can present in different ways. Lameness does not always correlate to the degree of actual ligament injury.

Be aware of potential risk factors to provide the best care for your dog.

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Torn Cruciate Ligament Risk Factors

Research suggests there are several risk factors for progressive cruciate ligament ruptures in dogs.


Some breeds are more prone to cranial cruciate disease due to genetics. Breeds prone to CCL disease include Rottweiler, Newfoundland, Staffordshire Terrier, Mastiff, Akita, Saint Bernard, Chesapeake Bay Retriever and Labrador Retriever.

Likewise, some breeds are very unlikely to develop CCL disease. Unlikely victims include the Basset Hound, Dachshund, Greyhound, and Old English Sheepdog.

Body Weight

Heavier dogs are more likely to suffer cranial cruciate injuries than lighter dogs. Heavier body weight causes more stress to the joints.

Neutering and Spaying

Testosterone and estrogen play an important role in elasticity and strength of connective tissue. Desexing removes hormones, leaving the canine cruciate ligament less elastic and resilient.


Unfortunately, aging affects all dogs and there’s no way to prevent it. Aging contributes to the degeneration of the ligaments, which is unavoidable.


Conformation refers to the shape and configuration of the skeletal structures. Certain shapes and sizes of bones can make a dog more prone to CCL injury. How bones meet at particular angles during movement is also a factor.

Other Orthopedic Diseases

Orthopedic diseases like patellar luxation or hip dysplasia often contribute to cruciate tears.


Less active dogs have decreased muscle mass, muscle strength, and ligament strength. Decreased strength increases the likelihood of an injury. Risk factors such as body weight, the age of neutering, and inactivity are in your control.

However, other risk factors are out of your control. Control the risk factors you can prevent.

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How Does a Veterinarian Diagnose Your Dog’s Torn Cruciate Ligament?

Your veterinarian will perform three tests to diagnose a ruptured cruciate ligament. They include the physical exam, x-rays, and manual instability tests. The physical exam analyzes the key indicators of Positive Sit Test, Medical Buttress, and Stifle Swelling.

Positive Sit Test

Normally, dogs sit with their stifles fully flexed underneath the pelvis. With CCL injury, dogs often sit with the entire leg out to the side. The splaying out of the leg while sitting reveals a "Positive Sit Test."

Medial Buttress

A medial buttress is a swelling on the inside of the stifle. The swelling develops in an attempt to control instability. Your vet discerns medial buttress by palpating the inside of your dog's stifle. Medial buttress swellings appear as early as one month after cruciate injury.


Effusion is swelling inside a joint. Effusion develops as a reaction to the torn fibers and shows up as a swollen knee. Your veterinarian will spot effusion during an exam. The presence of effusion confirms damage to the cruciate ligament.


Radiographs, or x-rays, allow your veterinarian to look for joint changes. X-rays of the stifle joint will show the presence joint effusion or arthritis. Both are diagnostic signs of cruciate damage.

Manual Testing

Manual testing for instability is a determining factor in cruciate injury diagnosis. The first manual test is cranial drawer.

Vets are able to palpate and examine most dogs while they are awake. Most dogs undergo cranial drawer testing while awake. But, if uncertain, your vet might need to examine your dog under sedation or anesthesia. It is imperative to compare the drawer of one stifle to the opposite stifle.

The second manual test is a cranial tibial thrust. A cranial tibial thrust tests the stability or lack of stability of the stifle joint. Cranial tibial thrusts let your vet know if the CCL tear is complete or partial.

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The Partial Tear

In a partial tear, individual fibers of the ligament tear, not the entire ligament.

Imagine a girl’s ponytail. The entire ponytail represents the cranial cruciate ligament. Every single hair in her ponytail represents an individual cruciate ligament fiber. When individual fibers tear and lameness occurs, the injury is called a partial tear.

Partial tears lead to lameness and swelling, but rarely to the gross instability of a joint. Some dogs adapt to partial tears and no surgery is necessary.

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The Complete Tear or Rupture

Sometimes, a complete tear results from trauma, like a football injury. But, as mentioned earlier, partial tears often escalate to full tears. Full tears cause joint instability and generally need costly surgery to correct. Surgery costs vary depending on the surgeon and the surgical technique employed.

The treatment for each type of tear depends on several factors including:

  • The size and weight of your dog
  • Your dog’s age
  • Other concurrent diseases
  • Your veterinarian’s experience

Unfortunately, treatment may be quite complex.

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Canine Torn Ligament Treatment: What Are Your Options?

"We estimated that owners spent $1.32 billion for the treatment of RCCL in the United States in 2003." -Wilke et al. (

As you can see, pet parents spend a lot of money treating CCL injuries in their beloved pets, For this reason, treating a torn canine cruciate ligament is a big decision. The decision can be tough, confusing, and expensive. Every veterinarian has a different opinion.

First, let’s review the different canine cruciate injury treatment options.

Conservative Treatment

Conservative treatment is usually recommended for smaller dogs weighing under 25 lbs. With six weeks of rest, most smaller dogs return to near normal function. The exception may be a dog with a concurrent luxating patella or cartilage tear. The take-home message is little dogs almost never need immediate surgery.

NSAIDs, PSGAGs, and fish oil also often help smaller dogs recover. Orthotic braces are also popping up as a treatment option. But, the effectiveness of using braces for a torn ligament in a dog’s hind leg is not yet proven.


Surgery is generally the treatment of choice for dogs weighing over 25 lbs. Several surgical options exist including:

  • Lateral suture
  • TightRope
  • TTA
  • TPLO

You should consult with a qualified veterinarian to help you choose a surgical correction. All surgical techniques have pros and cons. Do your cruciate ligament repair research before making your decision. Surgery is usually the best option for cruciate disease because it is the only way to permanently control knee instability. The goal of surgery is not to repair the ligament, but to control instability and decrease pain.


Prolotherapy is an injection technique strengthening the fibrous tissue surrounding the joint. Not all dogs are good candidates for prolotherapy. Veterinarians usually use prolotherapy on older dogs with partial tears. Some vets, use prolotherapy as a preventative measure on the good stifle when doing a CCL on the other leg. From Dr. Smith’s experience, 50% of dogs who tear one knee ligament will tear the other within 6-9 months.

Regenerative Medicine

Stem cell therapy and PRP (Platelet Rich Plasma) are forms of regenerative medicine. Regenerative medicine is a new, exciting field of veterinary medicine. Regenerative medicine uses certain cell constituents to replace or rebuild diseased tissue. Some veterinarians recommend stem cell or platelet-rich plasma instead of surgery. Or, sometimes it’s recommended with surgery to further enhance healing the stifle.

The Best Philosophy for Treating Cruciate Disease and Injury

The best philosophy is to offer a variety of treatment options to you, the pet owner. Tailoring treatment options addresses the unique needs of your pet and family. Tailoring your options minimizes the emotional stressors of making a big decision.

Consider the following when making your decision:

  • Your pet’s activity level
  • Size and age of your dog
  • Conformation of the back leg
  • The degree of knee instability
  • Cost of chosen treatment
  • Deep thought and consideration are necessary for a successful outcome.

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TPLO for Dog Cruciate Ligament Tear: What You Need to Know

Many surgical treatment options are available for a cranial cruciate ligament injury. TPLO stands for (Tibial Plateau Leveling Osteotomy). TPLO is a very common surgery recommended by board-certified veterinary surgeons.

Another name for the TPLO is “bone cutter.” During a TPLO surgery, the surgeon makes a circular incision in the tibial plateau. He then rotates the tibial plateau until it is level with the patellar ligament. The surgery places the tibial plateau at a 90-degree angle to the patellar ligament. The reorientation of the tibial plateau renders the knee stable.

The surgeon also inserts a bone plate and screws to stabilize the cut in the bone. After the bone heals, the bone plate and screws are not needed. But, they are only removed if there is an associated problem.

With a TPLO, the cruciate ligament is no longer needed to stabilize the knee.Many dogs continue to have cranial drawer signs even after a successful surgery.

In PET | TAO co-founder Dr. Marc Smith’s experience, TPLO is superior to suture stabilization in giant breeds of dogs.

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What Happens After Cruciate Surgery?

The following recommendations apply to both the TPLO and TTA. Most dogs can go home the next day after surgery with pain meds and specific instructions. Follow postoperative care instructions to avoid complications.

Right after surgery, care for the incision and make sure your dog wears an E-collar. Do not remove the E-collar because you feel sorry your dog. Everyone feels sorry for their dog; but, you must do what is in your dog’s best interest. Removing your dog's E-collar can be disastrous. Many dogs immediately start licking and scratching the incision, leading to suture breakdown and infection. Wearing the E-collar until suture removal is mandatory.

The incision will be on the inside of the leg, and keeping the incision clean is necessary. Use a warm semi-moist hand cloth to remove dried blood and any drainage. Some veterinarians will bandage the leg after surgery. Every surgeon is different.

Application of ice packs to the leg 2-3 times daily for 10-15 minutes can decrease pain and swelling. You will need to return to the vet to remove sutures or staples in 10-14 days. By then, most dogs will be using the leg and ambulating pretty well.

You must all rehabilitation instructions for the surgery outcome to be successful. Veterinarians cannot emphasize this fact enough.

Many dogs are walking well 21 days post surgery. So, owners assume they've fulfilled their surgery commitments. Do not let this fool you! The bone still has a long way to go for complete healing. If you don't continue restraining your dog, complications can be disastrous! You will need to restrain your dog on a leash for four months after surgery.

Four months is how long it takes the bone to heal. Four months is non-negotiable. Restrain your dog for at least 4 months!

When a TPLO surgery goes well, owners are very happy and dogs are too. But when complications arise, it's a nightmare.

The most common complications include:

  • Swelling
  • Bleeding
  • Incisional infection
  • Suture breakdown

More serious complications include:

  • Bone infection
  • Plate failure
  • Tibial fracture
  • Cancer at the osteotomy site (rare).

TPLO torn cruciate ligament repair is a fantastic surgical procedure when all goes well. But, when complications arise, owners are often dejected and ask themselves why they made the choice of TPLO.

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TTA for Torn ACL in Dogs: What You Need to Know

TTA stands for Tibial Tuberosity Advancement. A TTA is another often performed surgery for a torn ACL in dogs. TTA surgeries are generally performed by board-certified surgeons. The goals of a TTA are much like those of a TPLO, so we'll share the differences here for you.

Like the TPLO, the TTA a “bone cutter” surgery. TTA requires an osteotomy or cutting of the bone to achieve the desired result. Many of the same complications for the TPLO also apply to the TTA. The surgeon recommends a TPLO or TTA according to his or her preference.

What are the main differences between the TPLO and TTA?

The TPLO requires more soft tissue elevation, which may explain why dogs who undergo TTA regain use of the limb faster.

Often, dogs who undergo TTA begin to use the leg 5-7 days after surgery. TTA is a simpler technique which many general practitioners perform. TTA implants have a slender profile and are generally made of titanium. TPLO implants are often made of stainless steel and tend to be bulky. Thus, swelling on the inside of the knee tends to be more pronounced in TPLO-treated dogs.

Following TTA surgery, the tibial tuberosity is more pronounced. Some owners find the appearance cosmetically unacceptable.

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Why Choose TPLO or TTA?

Why would a surgeon recommend a TPLO or TTA when other less invasive techniques exist?

Surgical Preference

Once a surgeon masters a technique, it's often easier to just go with what you know best.

The Dog's Size

As a rule of thumb, dogs weighing over 50 pounds need a “bone cutter” surgery or TightRope. But, not always.

Base your decision on the advice of your veterinarian. Many dogs weighing over 50 pounds do well with other techniques. It depends on the dog.

The Dog's Size and Age

Young, larger dogs typically need a “bone cutter.” The simple reason is that one of the goals of surgery is to prevent the progression of arthritis. “Bone cutters” are quite effective at limiting arthritis progression compared to other procedures. TPLO and TTA work well for most active (athletic) dogs of large size with good to excellent results.

Note: The majority of lateral suture stabilization complications occur in younger, more athletic dogs. For this reason, a “bone cutter” is a better choice for young, athletic dogs.

Additionally, reports show a faster recovery period with "bone cutter" surgeries. Postoperative weight-bearing is not unusual within the first 24 hours after surgery. Also, additional evidence shows larger athletic dogs perform close to their pre-injury status. Historically, other techniques (lateral suture) have not yielded such good results.

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Extracapsular Repair of Torn Cranial Cruciate Ligament in Dogs: What You Need to Know

General practitioners often use extracapsular repair because of it's simplicity and cost. Another name for extracapsular repair is the “fishing line technique.”

Extracapsular repair techniques have been available for over 50 years. They have proven the test of time as a very beneficial surgery for a torn cranial cruciate ligament. The most common extracapsular repair options are the Lateral Suture and TightRope techniques. Extracapsular means the correction and stabilization occur outside of the joint. Neither procedure requires a cut in the bone.

Compared to TPLO and TTA, the advantages of Lateral Suture and TightRope are:

  • Lower cost
  • Less significant complications

Lateral Suture

The lateral suture is the simplest technique. Lateral suture requires only an incision on the outside aspect of the knee.


  • Simplicity and ease of the surgical technique
  • Short operative time
  • Good results
  • Low complication rate
  • Low cost

If a complication from surgery occurs, the surgeon can remove and replace the suture.


  • Difficulty in proper placement of the suture
  • The surgeon must isometrically place the suture for best results

Stretching of the suture may occur requiring a revision surgery. Stretching is most common in larger dogs.

The TightRope Technique

The TightRope technique is the most recent advancement in extracapsular stabilization. The TightRope incorporates as many advantages as possible.


  • The strongest extracapsular stabilization implant available today.
  • May perform superior to other extracapsular sutures with respect to suture stretching.
  • More isometrically placed than other extracapsular techniques.


  • The cost is more than the lateral suture. (Slightly less than the TPLO or TTA.)

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Why Choose a Lateral Suture Surgery Over a TPLO or TTA?

Cruciate surgery is a tough decision. You must take into account varying factors and make your decision with the help of a trusted practitioner. The following are reasons are why some veterinarians recommend Lateral Suture Surgery over others.

Less Complications

With extracapsular surgeries, catastrophic failure necessitating amputation or euthanasia usually don't occur. If complications do occur, they are generally not as disastrous.

Lower Cost

Extracapsular techniques are more cost-effective. Extracapsular techniques are also easier to perform than osteotomies of the proximal tibia.

Bottom Line

Board Certified surgeons usually recommend "bone cutter" surgeries for dogs weighing over 25 pounds. The best veterinarians take into consideration owner expectations, the dog’s health status, cost-effectiveness, and more to arrive at the best surgical option.

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Action Items

Complete the following action items, and you'll be well on your way down the path to better health for your pet!

  1. Learn more about dog knee injuries and cranial cruciate options by downloading our free ebook "What Your Vet May not Tell You About Torn Knee Ligaments!"
  2. Find out if dog's cruciate tear is a partial tear or a complete tear. Different options are available for each.
  3. Start your dog on oral or injectable glucosamine.
  4. Begin a program of crate rest. 
  5. Always consult with your veterinarian before making changes to your dog's diet and exercise routine.

Free Ebook: What Your Vet May Not Tell You About Torn Knee Ligaments