ACL Ruptures in Dogs

[kandy]

In May of 2005, my husband and I got our second Newfoundland, a female pewter newfie that we named Hazel. During that first summer, we saw that she was severely pigeon toed, both front and back. In the summer of 2006, she started limping.

Because she had not suffered an actual injury, at first we thought she had bruised her paw on the rocks at the lake we frequent. The limp would seem to get better, and then worse again, and then better again. Of course we took her to the vet several times for the limp. Our vet diagnosed the limp as panosteitis. After researching that condition, I was unconvinced that the diagnosis was correct, as Hazel’s limp did not change legs. We requested x-rays. Again our vet said that there were no problems indicated in the x-rays and that she was convinced it was pano. During the spring of 2007, Hazel’s limp got worse, even with her prescribed pain killer, deramaxx. At different times during the late spring and summer, Hazel refused to use the leg and held it in the air more and more often. Finally in August of 2007, I felt like the pano should have resolved itself if the diagnosis had been correct, and since it hadn’t, it was time to insist on answers.

I made an appointment for Hazel at Colorado State University’s Veterinary Teaching Hospital. We took the x-rays from our local vet with us. After a brief examination, we got the bad news. Hazel had ruptured her Anterior Cruciate Ligament. They arrived at their initial diagnosis because of the results of the ‘drawer sign’, which is where the vet can move the tibia forward while holding the femur stationary. If the ACL is intact, the tibia will not move forward (like pulling out a drawer). A vet may also do a ‘Tibial Compression Test’ where they hold the femur immobile and flex the ankle. If the tibia has any forward movement, the ACL is likely ruptured. Their initial diagnosis was confirmed through x-rays and an arthroscopic exam.

A dog’s knee is bent all the time. Because of the constant stress on the ligaments, dogs naturally have a high risk of rupturing a cruciate ligament but contributing factors such as weight, age, genetic predisposition and breed size play an important role. The knee of a dog has two cruciate ligaments that criss-cross to keep the femur & tibia stable and keep them from rubbing against each other. The Anterior Cruciate ligament (also called the cranial cruciate ligament) and the Posterior Cruciate ligament (also called the caudal cruciate ligament). These ligaments allow the knee to move like a hinge, but if one ligament or the other is stretched, torn or completely ruptured, the bones in the knee will slide against each other. If the condition isn’t treated, damage is done to the meniscus (the cushioning layer between the bones) and degenerative arthritis will quickly set in.

Because Hazel is severely pigeon-toed, her ACL was under tremendous stress from the time she was born and began using her legs. The ACL likely tore gradually, until it finally ruptured. The orthopedic vet at CSU explained that while technically I had two options, only one option was viable in Hazel’s case. The first option was to build and attach a new ACL, also called an Extracapsular Repair. This method replaces the ACL with a wire or large suture. Because of the malformation in Hazel’s legs and her size (120 lbs), the only true option for a successful outcome was to perform a Tibial Plateau Leveling Osteotomy, or TPLO. This procedure actually changes the angle of the tibia in relation to the femur, using the dogs own weight to create stability in the joint. Vets who perform TPLO’s must obtain a special certification before being allowed to perform the procedure. There is a third surgical procedure, called an Intracapsular Repair, which involves harvesting live connective tissue from elsewhere in the dog and using it to replace the ACL. A person may also choose to not have surgery but rather to employ medical management of the condition. As it was explained to me, and confirmed through many hours of research, a torn ACL will not heal and while the limping may decrease, leading a person to believe the injury has healed or is healing, the swelling in the surrounding muscles have actually created the illusion of stability. As the swelling decreases, so will the stability in the knee. For this reason, surgical repair of a ruptured ACL is recommended in almost every case. For smaller dogs, the Extracapsular Repair seems to produce favorable results. For dogs of Hazel’s size, the TPLO is the preferred surgical procedure for the best results in the long run. Historically, larger dogs that have had an Extracapsular Repair are more likely to require repeated repairs on the same knee. The Intracapsular Repair has the most risk of requiring repeated repairs and as such is being quickly overshadowed by the other two methods. All three procedures are surgically invasive, although the TPLO is the only one that involves cutting and realigning the bones.

In Hazel’s case, her tibia had to be cut and rotated to a normal position, and then adjusted to the correct angle before a metal plate was inserted to hold the bones together. We were advised to keep her totally confined and inactive for at least 4 months and possibly longer, depending on the level of bone healing indicated during her 4 month post operative check-up. We would have to strictly enforce the activity restrictions and would have to accompany her on bathroom breaks in the backyard, supporting her weight with a sling around her belly. She could not be allowed around any furniture unsupervised as the risk that she would jump up onto the furniture, or even back down to the floor, and break the leg at the point of realignment was too much to take. She would also not be allowed to be around any other dogs. We were lucky to be able to send our other dog for an extended stay with his cousins.

After Hazel’s release from the hospital, I took the first few days off work as we tried to determine how and where we would confine her. When we were home, we would keep her confined to the computer room by blocking the doorway, but the problem was how to confine her once I went back to work. Hazel had never been crate trained and was used to going to work with my husband every day. We decided that the bathroom met the criteria. It was small, but not tiny; it was carpeted; there was no furniture in it; and it was easily cleaned if she had any accidents. Hazel showed us the errors in our thinking as soon as we arrived home that evening. The bathroom door is old and isn’t solid, it has slats. We thought that it would provide air circulation but she showed us that it also provided a manageable escape route. She stuck her head through the slats towards the bottom of the door, and broke enough of them out to squeeze the rest of her body through it. Based on the blood on some of the slats, she also chewed through the ones that were not broken to her satisfaction. After the initial panic and a frantic exam to see how badly she had hurt herself, it was obvious that our confinement plan needed to be revised (although now we have a handy hole in the bathroom door so that all the dogs can actually watch you rather than just whining at the door). We decided that the next best idea would be to move all the furniture out of the living room, and use one section of our couch to block the entryway to the living room, with the back facing into the living room. It was a bigger room than we would have liked, but now she would have the television to watch. A major bonus for me was that I could actually use the couch to sleep on each night by just turning it around. I had been sleeping on the floor of the computer room at night to keep her company and my back was starting to complain loudly. The living room worked very well until right before it was time for her 4 month post operative check up.

I came home from work as normal, carefully opening the door so that I did not hit her with it. I opened the door and everything looked normal, the couch was in place, the TV was on – but Hazel was not in the living room! My heart jumped up into my throat, and then her head popped up from the other side of the couch. She had apparently decided her confinement should be over and had jumped the couch. We took her to an orthopedic vet who is certified to perform the TPLO but is much closer to us than CSU. He performed x-rays and said that the bone had completely healed, the angle looked to be correct and she could be released from her restrictions.

It’s been 13 months since her surgery. I no longer have people comment on ‘the old girl’ being gimpy – she now runs and plays like a 3 year old dog should be able to. So far, she has not shown any indication of her other knee having any problems, and during her 6 month post operative evaluation, the vets at CSU examined that leg and proclaimed it to be intact, for now. The odds are not in her favor though. Typically dogs that rupture one ACL will rupture the other, usually within a year. We are past that threshold, but with Hazel’s bone deformity, size, and genetics it is almost inevitable that she will rupture the other ACL. Hazel takes a glucosamine/chondriton supplement every day, and will take it for the rest of her life. We watch her weight carefully to make sure she stays at an optimum weight and her exercise program is moderate but consistent with lots of swimming.

If your dog begins limping on a rear leg, I would advise you to take the dog to a vet who is experienced in orthopedics for diagnosis. I was understandably upset that our vet had incorrectly diagnosed Hazel but the vets at CSU told me that unless a person has extensive experience with orthopedics, a ruptured ACL is easy to miss. In Hazel’s case, because she was so young and there had not been an actual injury, our vet had no reason to suspect a ruptured ACL. I believe that if our vet would have had more experience in orthopedics, she may not have misdiagnosed Hazel as she may have suspected that the bone deformity had caused undue stress on her cruciate ligaments.