Patella Luxation and treatment in Dogs

The following are real life cases of Patella Luxation in Dogs that have been treated by Dr. Mike Richards, DVM.

Luxating Patella Grading
Recovery from Luxating Patella Surgery
Surgery for Luxating Patella
Luxating Patellae in Pug Possible
Luxating Patella in young Pomeranian
Luxation of the Patella

Luxating Patella Grading

Question:

Luxating patellas of 2.5 or 2.0, just what are the significance of these numbers? What do they mean and can these numbers increase?

Answer: 

Luxating patellas are graded on a scale of 1 to 4 (some sources use 1 to 5).

Grade 1 are patella luxations that are found on physical exam by looking for them when the dog shows little to no clinical signs -- the patella can be luxated manually but doesn't do this much on its own.

Grade 2 luxations occur when there is occasional spontaneous lameness but the patella returns to normal positioning easily enough that the dog usually isn't pained much by it. This is typically the dog that occasionally carries a rear leg for two or three steps on occasion but then puts it back down and goes as if nothing was wrong.

Grade 3 luxations is usually used to describe dogs who are beginning to have a loss of function due to the luxation of the patella. They have more frequent "skipping" episodes, may not want to jump up onto things, they may have pain and the patella doesn't always return to normal positioning when it is deliberately pushed out of its groove during a physical examination.

Grade 4 luxations are when the legs are painful enough that the dog tries not to use them, when the leg can not be fully straightened manually and the dog shows evidence of chronic pain or disability, including poor to no ability to jump.

Grade 5 (or severe grade 4 depending on the grading scheme) is when the dog won't use the legs or when the gait is stiff legged due to the patella being underdeveloped or permanently dislocated and fixed in place outside its normal position.

Most veterinary orthopedic surgeons recommend repairing dogs in Grade 3+ without question and advocate fixing grade 2 dogs frequently. So a 2.5 grade is probably one in which the examining veterinarian is leaning towards thinking surgery is necessary. That is just my best guess on the interpretation, though. It is better to ask the vet who made it.

I think that most dogs generally get worse over time and move from Grade 1 to Grade 2 or from Grade 2 to 3, for example. The changes may not happen until later in life, though. A lot of dogs with Grade 1 or Grade 2 patella luxation early in life will have pretty stiff knee joints when they are 14 or 15 years old that probably are at least partially this way due to arthritis from the years of luxating patellae. There is a lot of other wear and tear in a long life so this is only a partial contributor but I know that some surgeons really feel that when the whole lifetime is looked at early surgery looks better. On the other hand, there are dogs who have bad outcomes from the surgery, too. I lean towards leaving knees alone until the Grade 3 stage, personally.

Get a general overview of Patellar Luxation in Dogs.

Question: 

I have some questions regarding my dog Scout's recovery from his luxating patella surgery. The surgery was done on February 6, 2001 by my regular vet. He has a continuing education certificate in orthopedic surgery and does several orthopedic surgeries each month and several luxating patella surgeries each year. (He's been practicing since 1984 or 1985). He said when I consulted him about the surgery that he has absolutely no problem referring clients to a specialist when he is not comfortable doing a procedure, but that he felt very comfortable about doing this particular surgery. We had Scout's anal glands removed and had an endoscopic exam of his trachea done at the same time.

Our vet was very happy with how the surgery went, and said that there was no indication of arthritis in the joint. During the surgery, he deepened the groove, inserted a pin, and tightened some things up. He checked the joint manually and with an x-ray after the surgery, and everything appeared to be well.

Unfortunately, three and a half months later, Scout is still not using the leg properly. He had two bad falls early on in his recovery which actually made him scream in pain. However, within 5 minutes after each fall, his pain was gone and the leg was no longer sore. There was no swelling either time. I had another x-ray done 2 months after the surgery, and everything still looked as it should. The vet said the pin was still straight and in position, and that there was no indication of any cracks in the bone, any infection, or any arthritis. He had the x-ray reviewed by a radiologist who agreed that everything looked normal. The vet thoroughly examined his leg and said that he couldn't pop the knee out of joint if he wanted to. Scout's muscle was atrophied due to lack of use, however.

Scout still lifts his leg up on his walks about once every 20 steps or so, sometimes more, sometimes less, especially when he is "jogging" rather than walking or running. In the house, he often picks up the leg entirely and runs with three legs from room to room. The exception is when we are playing fetch--then he uses all four legs properly. It is discouraging that his leg seems just as bad now as it was before surgery.

I worry that I may have exercised him too much, too soon. I was careful not to let him jump on or off of things or go up and down stairs for 6 weeks. However, other than telling me not to walk him at all for about a week after surgery, my vet didn't give me any restrictions for exercise. Now, however, I've read several places on the internet that I should have kept the leg very well rested for anywhere from 10 to 14 weeks.

Scout didn't use the leg at all for a couple weeks after the surgery. Then, he started to use it when walking very slowly outside. After about 4 weeks, he was started to walk a little faster on it. The vet said I should walk him a lot to strengthen the leg, but I think I went overboard in walking him an hour and a half a day (three half hour walks, with a rest halfway through each one).

Scout is almost two years old. He took Rimadyl for about a month, starting two weeks after the surgery, to encourage him to use the leg more. Unfortunately, he had a bad reaction to the drug (including VERY uncharacteristic aggression, dilation of pupils and paranoia). He has been on Cosequin since the surgery.

So, my questions for you are:

1. Do you think I damaged his leg by exercising him too much after the surgery? If so, what kind of damage could I have done? 
2. What do you think might be causing his continued reluctance to use the leg, since the vet hasn't found any problems either with repeated examinations or with x-rays?
3. Are there any other tests I should have done (ultrasound, etc.) which might reveal the problem?
4. Should I take him to an orthopedic specialist at this point?
5. Do you have any other suggestions?

I am very worried that he may never use his leg normally again. He may also have to have surgery done on his other knee at some point in the future.

Answer: 

Most of the time we refer joint surgeries to an orthopedic specialist because we do not have the opportunity to do enough of these surgeries to feel confident doing them. So I can only report with information from the literature and give you some perspective based on the follow-up care that our clients have been advised to provide.

1. The standard post-operative recommendations are to use a padded bandage for 3 to 7 days after the surgery (these were the shortest and longest recommendations) to control swelling and provide some support. After the bandage is removed, it is recommended most frequently that leash walking only be allowed for 4 to 6 weeks. Some texts recommend passive physical therapy (moving the joint through its range of motion manually for 40 to 50 times once or twice a day) as well. Swimming is occasionally recommended, as well. It is unlikely that you caused any problems by leash walking Scout for a half hour three times a day.
2. You don't say how big Scout is, but it may have an impact on why he doesn't use the leg more. Very small dogs do really well on three legs and so they sometimes won't use a leg when there is only minimal pain or discomfort, just because it isn't a problem for them to carry it. Big dogs sometimes have a problem in which the portion of the femur (the long bone above the knee) is bowed more than small dogs when they have patella luxations and it is sometimes necessary to remove a wedge of bone from the femur to get better alignment in order for the surgical repair to work well. Without knowing for sure, I am guessing that it was necessary to move the tibial crest (the point where the patellar tendon attaches on the bone of the lower leg) and to pin it into place. This would explain the bone pin. In this case, the pin can sometimes cause pain and there is sometimes infection when pins are placed, which may not show up well on an X-ray for some time. These are not common complications but they are things to think about. There are some patients who simply don't respond to surgeries as expected. We have done surgery in several instances in which we really thought the surgery went well, the post-operative care was good and yet the surgical outcome was still not what we hoped for. This is probably more common in orthopedic surgeries than in other forms of surgery, since there can be hidden changes in bone or joints and sometimes fixing one problem creates pressures or problems in other areas. In a study of medial patella luxations repaired surgically (Wilhlhauer, Vasseur, 1987) reported in "Small Animal Surgery" 48 of 52 patella luxation repairs worked well and 4 did not --- which is about 8% of the surgeries in which the outcome was not as good as hoped for.
3. Very careful re-examination of the factors that led to the patellar luxation can be helpful in figuring out if it is necessary to attempt further repair. Patellar luxation occurs because there is some sort of mechanical misalignment in most cases. This probably stars in the growth plates developing unevenly which causes the shape of the bones to change. The patella is then forced out of its normal track by bowing of the upper leg, by twisting of either the upper or lower leg or by some other anatomical force that makes the patella follow a different course than it normally does. This leads to a shallow groove where the patella runs since it is partly developed due to the pressure of the patella. So the surgical evaluation has to be geared towards figuring out which of these problems has occurred and repairing it. Sometimes it is harder to figure out what the problem is than other times and so a re-evaluation might be helpful. This would involve taking additional X-rays and looking for problems that might be leading to the lack of use of the leg. Since your vet has experience with these surgeries he may be able to determine if this is necessary or you can ask for a referral to an orthopedic specialist for evaluation. It is also possible your vet already did this. In some cases, especially in dogs that really do have a pretty good repair but are reluctant to use the leg, anyway, it can help to encourage use of the leg. This can be done by physical therapy (range of motion exercises, swimming, walking uphill slowly -- things that encourage use of the leg) or by doing something to force weight bearing by limiting use of the other leg. People do all sorts of things to discourage use of the unoperated leg, such as bandaging the "good" leg (since many dogs don't like to use a bandaged limb), taping a marble to the bottom of the "good" foot to discourage use and other things that sound even worse, to me. I think I'd recommend a visit to an orthopedic surgeon prior to trying these strategies, though. 
4. I think it might be helpful to get an opinion from an orthopedic specialist. I think this might be especially true if Scout is a big dog (like a boxer or Lab). The fact that Scout uses the leg when he is distracted enough (when playing) seems like a good sign, to me, that he might go ahead and use it soon but I don't know how long you want to wait to see on that.
5. Finding a pain reliever that you can use successfully might be worth one more try. If you could achieve good pain relief for two to three weeks and there wasn't a change, that would help some in making an evaluation of the prognosis and the need for re-evaluation for other problems. Etodolac (Etogesic Rx) might work OK even though carprofen (Rimadyl Rx) didn't. We use hydrocodone and aspirin pretty frequently in our practice, as well.

Find additional information on Luxating Patella Surgery for Dogs.

Question:

I have a one year old Cavalier King Charles Spaniel who has recently begun limping. Our vet has diagnosed her with mild luxating patella. What is your opinion about surgically treating this problem and when would you think is the "right" time to do this? Lucy is a jumper and will spin and jump at the thought of her dinner so we can't keep her "quiet."

Answer: 

Surgery for a luxating patella should probably be done as soon as it is clear that the problem exists. This is a surgery that should be done by a surgeon who is doing the procedure frequently, in my opinion. So we refer these cases to an orthopedic surgeon. There is a certain amount of judgment required during the surgical procedure about how far to go in attempting to stabilize the patella. Some dogs only require tightening of the joint capsule and fixation of the patellar ligament towards to opposite direction of the luxation. Other dogs require deepening of the patellar groove and some require deeping of the groove, reshaping of the patella and repositioning of the tibial crest (breaking the tibia bone where the patellar ligament attaches and moving it to allow a straighter course for the patella). The decision process must be made as the surgery proceeds in most cases.

Most of our clients do not pursue surgery for this condition. Most of the dogs with this problem will be able to function reasonably well but may not be able to jump up on things as readily as they could before the onset of the patella luxation problem. There is progression of arthritis in some dogs and we have seen four or five patients who became quite crippled over time due to severe complications of luxating patellas. We have seen one real disaster in surgery, when a client ignored our referral to an orthopedic specialist and found a general practitioner to do the surgery. After surgery it took almost six months for this patient to be able to walk without assistance. I am not sure that the surgeon was not experienced, as complications sometimes occur when surgery is done "according to the book" but it made my resolve to refer patients to specialists for this procedure even greater.

If you believe that Lucy is in pain, or that loss of some ability to jump would adversely affect her personality or enjoyment of life, then it would be good to consider surgery for this condition. If you think surgery would be helpful it should be done as quickly as possible so that the patella is still in good shape and there isn't much secondary arthritis to contend with. I practice in a rural area, so my chance to do this sort of procedure is limited. I am sure that general practitioners in the suburbs and cities have more opportunity to perform this sort of procedure and may be quite comfortable and quite competent with the procedure. I'd ask about that before allowing the surgery to be performed, though.

Question: 

I have a 6-1/2 year old female (intact) Chinese Pug, Casey, who has a strange cadence to her walk. We've noticed this since last Spring, and it seems to be becoming more prevalent (at least I'm noticing it more). Casey doesn't have the typical staggered 'dog walk,' but does more of an 'elephant' walk in which the front and hind legs of each side will advance at the same time, same rate; and her behind always seems 'crouched' when walking, tail all straightened out. In addition, while walking she sometimes will try to quickly sit down and her back leg (sometimes both at the same time) will start kicking, uncontrollably. Then she'll continue to walk normal, then stretch both back legs out, as if in a 'push-ups' position, and drag both back legs for a few steps. Then she'll quit and walk normal again. Our other 14-year old Pug still has a crisp gait, head held high, tail up and curly...

Casey also has some other strange symptoms. She constantly licks her 'wrists' and the underside of her paws. She's been doing that for years, I believe. And, for the past 6 to 7 months, she seems to have forgotten her potty-training skills (specifically defecating), as if she just can't quite wait to get outside, or even attempt to get outside.

Casey has never been injured, at least not that we know of. We've had her since she was about 12 weeks old. Any clues to what going on? Could it be hip dysplasia or degenerative joint disease? What would you do if you had a client with these problems? X-rays? MRI? Should we go to a specialist? What type? Do you know of any specialists available in the Phoenix, AZ Metro Area? Any information will be greatly appreciated. 

Answer: 

This may be an orthopedic problem. Dogs with luxating patellae can have the symptoms you are seeing in Casey. This is a condition in which the kneecaps do not stay in the groove they should travel in. They pop out, usually to the inside of the leg, producing pain, apparent weakness, difficulty jumping (common) and difficulty moving (less common). This same set of symptoms can also occur when both cruciate ligaments are ruptured at approximately the same time. Dogs with luxating patella problems usually get worse over time, while dogs with cruciate ligament ruptures usually get better over time.

This may also be a neurologic problem.There is a neurologic problem peculiar to pugs, known as pug dog encephalopathy or chronic encephalitis of pug dogs. It could cause the signs you are seeing but seizures are usually associated with this condition. There are several other encephalitis or menigoencephalomyelitis conditions that can cause these types of signs. Spinal disc disease can sometimes cause these types of problems, too.

This is one of the those times when you have to pick which direction to go in for testing and then if that doesn't work out, go the other way later. I think I'd lean towards orthopedic problems first, personally, since they are easier to test for and then worry about neurologic problems if orthopedic problems aren't found. Your vet should be able to refer you to an orthopedic surgeon for evaluation, if he or she is not comfortable making the diagnosis. These are common problems in general practice and most vets would be reasonably comfortable at least making an initial evaluation, although it may be necessary to make a referral for the actual surgery if the orthopedic problems seem likely after the initial exam.

You could easily make a case for seeing a neurologist first, especially with the behavioral changes. If it is easier to see a neurologist in your area, I wouldn't hesitate to do that first. Orthopedic problems can interfere with housebreaking behavior, too, though.

Your vet can help you decide which direction to go in after an examination.

Question: 

Please advise how YOU would treat a pre-adult Pomeranian with a newly DX'd "Trick Knee."

Answer:

The question regarding the Pomeranian's stifle joint is hard to answer without knowing exactly what is wrong and without sounding wishy washy if it is the most common problem, which is a medial luxation of the patella (dislocation of the kneecap towards the inside of the knee). The truth is that most of the time we do nothing for these puppies, except explain to their owners what is happening and pointing out that surgery is an option. If they are interested in surgery we refer them to a surgical specialist because fixing these requires some judgment calls on how far to go, that we do not feel comfortable making. If the problem is obvious in a very young puppy (less than four months) we will sometimes do surgery because at this age it is unusual to have to relocate the tibial crest and we can still cut through the bone (the femur) to remodel it with a scalpel and I am more comfortable with a scalpel than with bone saws. Based on our client's pets, many of whom do not have surgery, most dogs adapt to this problem and seem reasonably comfortable, although pain relievers are sometimes necessary but have less active lifestyles and do not jump well. A few dogs seem miserable and we try harder to get people to consider surgery for this group. 

Question:

I have a 3 year old westie who has been limping (left hind leg) for over one week. After sleep he continues to limp but at times will regain use of his leg especially when distracted by adventure! I was told by the vet that he may have a chronic knee problem or arthritis. What can I do to correct this problem? I would appreciate any help that you could offer at this time about medication or other avenues to correct this or to lessen his pain. I feel so helpless.

Answer:

I am hoping that you have taken your westie back to your vet to find out exactly what the problem is. It is just not possible to figure out the best course of action without knowing what the cause of the problem is. If this still continues to be a problem it would be best to check it out. A likely problem is luxation of the patella (dislocation of the kneecap) in the affected leg. Degeneration of the cruciate ligament is also pretty likely and there are a number of other possible conditions. After a diagnosis is made your vet will be able to provide you with information on the best way to handle the problem. At this age there is no reason to put off finding out what is going on since your dog may have to live with the problem a long time. Minimizing the pain by correcting the underlying problem, if possible, is definitely better in young dogs.