Is Surgery Really Necessary for Dogs with Ruptured Cruciate Ligaments

In a recent article concerning an herbal product used for treatment of a dog with a ruptured cranial cruciate ligament (the equivalent of the “ACL” in humans), I stated, “Surgery is the treatment of choice for a ruptured cruciate ligament. Weight loss, physical therapy, and possibly medications are all helpful and important, but without surgery a large dog will have permanent instability in the knee and will develop progressive arthritis.” One of my regular readers challenged this statement and referred to evidence in humans suggesting that surgical therapy was no better than non-surgical therapy in treating this disease. This stimulated me to look into my assumption that surgery was superior to medical management for large dogs and see whether or not the evidence supports this claim.

Following the usual approach I take in evaluating a proposed therapy, I will look at the plausibility of the intervention first. A great deal has been written about the biomechanics of the canine knee and all the factors that may play a role in cruciate ligament ruptures (e.g. 1, 2, 3, 4, 5, 6, 7, 8). The bottom line of all this is that ruptures of the ligament are caused by multiple interacting factors including breed (and hence genetic influences), size, the structure of the canine knee, and activity. The various surgical procedures recommended for this disease are all rational and plausible based on a detailed understanding of the basic biomechanics of the disease.

There have also been many studies looking at the effect of various surgical procedures in animal models of the disease, usually laboratory dogs with ligaments that have been deliberately damaged. While this sort of model does not replicate all the features of naturally occurring disease, it can provide some clue as to whether the surgical therapies are likely to be effective. These sorts of studies, often used as models for arthritis in general, show clearly that severe joint disease and marked dysfunction results over time without surgical treatment of a ruptured cruciate ligament (e.g. 9, 10, 11, 12, 13, 14, 15)

There is extensive clinical research in humans concerning whether surgical repair of cruciate ligament rupture is necessary. I am quite skeptical of the applicability of this research to the same question in dogs since the biomechanics of the canine knee are quite different from those of the human knee. Also, conservative management for humans includes exercise restriction, physical therapy, and often immobilization of the knee with a brace, all of which are challenging and not often used in dogs with ruptured cruciate ligaments. However, the basic anatomy and pathophysiology of arthritis are quite similar, so research in humans may have some value in answering the question for dogs.

The results of clinical trials in humans are mixed. One Cochrane Review examining older surgical techniques found they were generally superior to conservative management. Some studies have found no advantage to surgical management, but these are not large or methodologically robust trials. It appears that both conservative and surgical management can have good outcomes, but the differences depend on the patient population (age, nature of injury, activity level, compliance with treatment, etc) and the specific therapy employed, so not incontrovertible conclusion can be made as to whether surgery or conservative management is superior overall.

There are a many studies looking at the outcome of surgical treatment of cruciate ruptures in dogs. Overall, they find good outcomes in the range of 70-80% or more of patients returning to normal or near normal function (e.g. 16, 17, 18, 19). Comparisons of different methods of surgical repair do not support the clear superiority of one method. However, there are few studies directly comparing surgical and non-surgical treatment in dogs. The best of these, published in 1984, compared outcomes of non-surgical treatment in dogs weighing more or less than 15kg (about 30lbs). For the dogs over 15kg, only 19% were normal (7%) or improved (12%)  years after their injury, and all had clear evidence of severe arthritis in the affected knee. For dogs weighing less than 15kg, almost 86% were normal (75%) or improved (11), and while all of these had evidence of moderate arthritis, it did not seem to affect the function of most of these dogs. Other less rigorous studies have the same general findings (20, Paatsama S: Ligament Injuries of the Canine Stifle Joint: A Clinical and Experimental Study. Master’s thesis, Helsinki, 1952) 

As is almost always the case, the evidence is not of the highest possible quality or unequivocal, but this does not exempt us from having to draw conclusions and make recommendations to our clients. My interpretation of the available evidence is that overall, cruciate ligament disease causes significant arthritis and loss of function when untreated. For most dogs under 15kg, conservative management (primarily restricted activity for 3-6 weeks, achieving and maintaining and appropriate body weight, and possibly physical therapy and pain medication) can achieve acceptable comfort and function. In larger dogs, significant arthritis is inevitable and dysfunction is extremely likely without surgical treatment. No single surgical technique is clearly superior, so the choice of specific surgery should be determined by the judgment of the individual surgeon and the needs of the owner.

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203 Responses to Is Surgery Really Necessary for Dogs with Ruptured Cruciate Ligaments

  1. Gabby says:

    Hello. I have a 2 year old rescue boxer. I found out early that she had AS and wasn’t gaining weight (originally 49 lbs). She also has this weird dripping from her lady parts. I put her on a gluten free diet and she finally started to gain weight. Also probiotics and other natural supplements were given to her. The dripping has nearly stopped completely and she finally was 60 lbs. She also was seeing a chiropractor that has done really well for her. So her knee was always a concern where she would limp randomly for maybe a few hours and be fine. We were doing rehab but the knee always would act up and we couldnt do more until it settled. She was making so many improvements and I was so excited.

    8 months into having her her knee was acting different. She was limping more and it wasn’t the same. I took her into an orthopedic that took xrays and she completely blew out her ACL. The xrays also showed how much degeneration she had in her knees already at 2 years old. This further supports a theory that she was raised in a mill, malnourished, an over vaccinated. Also an accident early on with being hit by a car or jumping out of a moving one with her AS.

    I’m stuck on what to do because I’ve heard to rehab it and do the TPLO. As a chiropractic student I understand the biomechanics and complexity of it. If I do the surgery I plan to ice, use the Assisi Loop, tape, and rehab the crap out of it.

    In her case I’m confused on what to do. I realize no one can tell me what to do but I appreciate opinions since it’s a big decision. Based on your clinical experience and knowledge what would you suggest? Do you know of any studies with dogs with AS or anything for that matter?

    Tootsie Roll is an active, caring and amazing dog that I just want to make the right decision for her. I’d like to make her a therapy dog because she’s wonderful and brings so much joy. She’d be perfect in an office setting. She’s been through a lot and I’ve had her for 10 months now.

    I appreciate your advice and time!

  2. skeptvet says:

    To begin with, I am not sure what you are referring to in saying “she had AS,” so I can’t comment on that. What condition are you referring to?

    Otherwise, you probably won’t be surprised, if you have seen much of my blog, to see that I have a rather different approach than you do to healthcare generally, so I’m not sure how useful my perspective will be. I don’t mean any of this personally, but there are a lot of assumptions and beliefs implied in your comment that I simply think are unproven or untrue, and it’s hard to give my advice on TPLO without starting by pointing out what I see as misconceptions or false assumptions.

    I put her on a gluten free diet and she finally started to gain weight. Also probiotics and other natural supplements were given to her. The dripping has nearly stopped completely and she finally was 60 lbs.

    The fact that her condition improved while you were doing these things is not, of course, evidence that these things worked. That is, after all, why we need science and why anecdotes and testimonials are unreliable. There is no reason to believe a gluten free diet has any value other than for the tiny subset of Irish Setters with true gluten intolerance. And the majority of supplements have never been tested to determine what if any value they have. Anecdotes alone, don’t suffice. I’m not sure what the DC was treating her for, but the only thing chiro has ever been shown to have reasonable value for is back pain in humans, so there is no evidence it is useful in dogs, and certainly not for knee problems.

    he xrays also showed how much degeneration she had in her knees already at 2 years old. This further supports a theory that she was raised in a mill, malnourished, an over vaccinated.

    There is absolutely no relationship between vaccination and degenerative joint disease so this is simply untrue. There is a relationship between hip and elbow dysplasia and excessive calories and calcium in growing large-breed puppies, but apart from the effect of obesity in overfed dogs, there is no known relationship between nutrition and cruciate ligament diseases, so this too is just a hypothesis or belief, not a fact. Genetic factors, age at neutering, trauma, some medications (e.g. fluoroquinolone antibiotics) raise the risk of some joint problems, but your are simply stating your beliefs as if they were facts, and the evidence doesn’t support them.

    If I do the surgery I plan to ice, use the Assisi Loop, tape, and rehab the crap out of it.

    Physical therapy and icing have reasonably good evidence to support them in humans, so while there is zero evidence in dogs it is a reasonable thing to do. PEMF devices like the Assisi loop are, again, not supported by very good evidence, though probably harmless.

    As far as the TPLO itself, as I’ve said in this article and in the comments, the evidence clearly shows surgery is effective in most dogs. What we don’t know is if non-surgical treatments are as good (braces, PT, etc). For this young a dog with existing degenerative joint disease, my experience suggests she is going to be crippled quite early without surgery, but again there are no studies comparing surgery with non-surgical alternatives so that is just an opinion.

    Good luck!

  3. art malernee dvm says:

    Human cruciate surgery is not what its cracked up to be for humans.

    The last three friends of mine did not get surgery so I suspect most cruciates are treated medically in human medicine but I do not have that data.

    The vet surgeons promote dogs need surgery when human knees would not because they do not walk on two legs and are not included in the RCT link above.
    I’m not sure what they think of the need for cruciate surgery for this subset of dogs below.

    There was just a study published in human medicine that showed no benefit for special costly rehab after artificial knee replacement. Sometimes the best treatment is no treatment.

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