Luxating Patellas - What Can You Do?

What is a luxating patella?

A luxating patella (kneecap dislocation) occurs when the knee cap moves out of its natural position. The patella normally lies in a grove that is coated with cartilage at the end of the thigh bone just above the joint space.  It is bean or almond shaped and it's job is to help with extension of the knee.  The end of the quadriceps muscles form the patella tendon and attach it to the shin bone on a bump called the tibial tuberosity.  The patella sits inside the tendon and rides in the groove mentioned above.  When quadriceps muscles contract, they pull on the tendon and the knee cap, resulting in extension of the knee. If the patella is pulled out of its normal groove with knee extension, this is called a luxating patella.  If it is pulled toward the inside of the leg it is referred to as a medial patellar luxation (MPL).  If it is pulled toward the outside of the leg it is referred to as a lateral patellar luxation (LPL).

The causes of this condition can be congenital, genetic and/or traumatic. Certain breeds are more likely to have or develop this condition.  These breeds are Miniature and Toy Poodles, Maltese, Jack Russell Terriers, Yorkshire Terriers, Pomeranians, Pekingese, Chihuahuas, Cavalier King Charles Spaniels, Papillons and Boston Terriers. Large breed dogs prone to this condition include Labrador Retrievers, Golden Retrievers, Akitas, Malamutes, Boxers, Huskies and St. Bernards.  Any dog with minimal hock angulation or poor body condition can also develop luxating patellas.

This condition is usually diagnosed early in life when the owner notices that the dog limps, skips or stretches the limb behind them repeatedly.  Some dogs with patellar luxation will sit with the knee extended out to the side.  All of the symptoms however are intermittent meaning they come and go until there is damage to the cartilage and arthritis is starting to set in. 

Luxating patellas can lead to a ruptured cranial cruciate ligament (commonly known as the ACL in humans). It is proposed that at least 15% to 20% of dogs with patellar luxation will eventually rupture their cranial cruciate ligament because the patella luxation changes how the knee works and thus puts more stress / strain on the cruciate ligament and in chronic cases the arthritic changes in the knee set off an inflammatory cascade that weakens the ligaments of the knee.

Luxating patellas are diagnosed during a pets physical examination with their veterinarian and are graded based on the severity of the condition.  Grade 1 means the kneecap will pop out of place but can easily be put back into a normal position.  Grade 4 means the kneecap is stuck and sits outside the groove at all times.  Grades 2 and 3 are in between. is usually diagnosed by feel and is assigned a grade based on the severity of the condition. 

Dogs with Grades 1 or 2 can do quite well without surgery and often can recovery with rehabilitation therapy alone.  Dogs with Grade 3 or 4 luxations typically require surgical repair to prevent further pain and arthritic changes from occurring.

If your dog suffers from this condition, the earlier you intervene the less likely your pet will develop arthritis and you may be able to prevent him from going through surgery.  The best way to support your pet is to start supplements and schedule an appointment with a rehab veterinarian to start a safe and effective home exercise program.

Supplements

Omega 3 fatty acids (fish oil) - these are natural anti inflammatories and can be very helpful in slow the onset of arthritis due to inflammatory mediators in the knee joint

Glucosamine / Chondroitin / MSM - these are the building blocks to healthy cartilage / joint tissue and can help to keep the joint healthy

Polysulfated Glycosaminoglycans - these injectable medications help to promote healthy cartilage in the joint.

There are also a few whole food supplements on the market that can support healthy musculoskeletal and ligamentous tissues but are available only with a prescription.

Exercise

xercise is the other component that can be very helpful in correcting patellar luxation.  If you pet has medially patellar luxation then it is likely that his quadriceps and lateral thigh muscles are weak.  If your pet has lateral patellar luxation then it is likely that his quadriceps and medial thigh muscles are weak.  With the help of a rehabilitation veterinarian a home exercise program can be developed to strengthen these areas in the earliest stages before problems have developed.

 What to do next 

If your veterinarian has indicated that your pet has patellar luxation here are the best steps to take.

1.  Start Glucosamine / Chondroitin Supplementation (talk to your vet about the product they prefer)

2. Start Adequan or Pentosan Injections (talk to your vet about the product they prefer)

3.  Have xrays of the knees and hips taken to evaluate the joints for arthritis or other changes

4.  Ask your vet for a referral to a rehabilitation veterinarian or therapist to start a home exercise program.  

(If your pet is a puppy ask for a referral to a rehabilitation veterinarian or therapist right away as we may be able to prevent the issues from developing at all)

Arthritis and Your Pet - What Can You Do?

Osteoarthritis / Degenerative Joint Disease is a disorder of movable joints characterized by the degeneration of articular cartilage and the laying down of new bone at joint surfaces or margins.  (In plain English the smooth surfaces inside the joint get rubbed away and then the body lays down new bone to stabilize what it thinks is an unstable surface.)  It is one of the most common joint diseases diagnosed in dogs and cats.

How Does Arthritis Happen

Osteoarthritis can be a primary condition due to defect in cartilage production (this is rare) or a secondary condition as a result of abnormal forces or stress being placed on the articular cartilage inside the joint.  This stress can be from abnormal forces being applied to the muscles, tendons, ligaments, joint capsule or bones that are involved in a particular joint or in stabilizing of the joint or can be secondary to an infection, developmental anomaly or immune mediated disease causing inflammation inside the joint.

When the articular cartilage is damaged this sets off a cascade that eventually will lead to arthritis.  Articular cartilage is composed of a few cells called chrondrocytes that secrete the matrix they are surrounded by. This matrix is composed of water, collagen, proteoglycans and hyaluronic acid.  Each of these components has a different job to do to keep the joint healthy.  The water and proteoglycan mixed together fills a collagen matrix to act as a shock absorber and distribute the forces evenly throughout the joint.  The hyaluronic acid helps to pull the water and proteoglycan into the collagen matrix and keep it in place, as well as increasing the thickness of the joint fluid to aid in joint lubrication.  Articular cartilage is a dynamic tissue that is constantly changing and resynthesizing components to remain healthy.  If the forces are too great on the articular cartilage then degeneration starts to occurs.  As this process progresses the structure of the proteoglycan being produced changes and it is easier to pull out of the collagen matrix decreasing the ability of the joint to absorb shock as well which leads to further cartilage damage.  The progressive damage to the cartilage causes inflammation (release of inflammatory mediators) which results in the  release of 4 destructive enzymes that lead to further decrease in the production of hyaluronic acid, proteoglycans and start to break down collagen to some extent.  

(In plain English) The stresses on a joint are to great and lead to damage to the cartilage.  This damage results in inflammation and the release of inflammatory mediators and destructive enzymes.  The destructive enzymes further damage the cartilage and change the proteoglycans and amounts of hyaluronic acid and collagen in the cartilage.   This process will continue until there are areas of articular cartilage that are completely gone and the underlying bone is exposed inside the joint.  The body then starts to lay down new bone as it would if a fracture had occurred.

Most patients suffering from osteoarthritis will present to their veterinarian for a gradual onset lameness that seems to get worse with exercise.  They will avoid or resist activities which previously were not a problem such as going up or down stairs, jumping on or off the bed or going for walks.  They may be worse after periods of rest, if they are overweight or if the weather is cold and damp.

What Can Be Done to Help Your Pet

Once arthritis has been diagnosed it is often a painful condition for your pet but there are many options available to help them to maintain a normal level of activity and still be comfortable.

Weight Reduction - many pets that suffer from arthritis are overweight or even obese.  The extra weight continues to apply abnormal and unnecessary stresses on their joints.  Getting your pet to an appropriate weight is absolutely essential in the management of arthritis.

Home Exercise Program - pets that suffer from arthritis usually developed arthritis because of abnormal movement in the body.  A rehabilitation therapist or veterinarian is the perfect partner in helping your pet to move better and to build up muscles to prevent the abnormal movement occurring in other areas of their body.  Scheduling a consultation for your pet early in the course of disease is ideal as this can help to slow the changes occurring in the joints and keep your pet mobile and comfortable for many years to come.

Acupuncture - using the energy flow in the body to help alleviate pain is becoming increasingly common in veterinary medicine. Acupuncture has very few negative side effects and can be a powerful tool to help eliminate your pets pain.

Laser therapy - laser therapy is used to help re establish normal blood flow to areas and to encourage healing.  It is a great option for pets that is minimally invasive and has very few negative side effects.  In fact many pets love their laser treatments and are happy to lie still for this.

Massage - when there is a lack of motion in one area of the body due to arthritis then is too much motion created in another.  Massage can be a very powerful tool to help alleviate muscle spasms, tightness, swelling and re establish blood flow to areas of the body.

Medications - there are a lot of medications available to help control pain and inflammation that is associated with arthritis. Some of these medications are appropriate only for dogs as cats metabolize drugs differently.  This will be noted in the information.

Non steroidal inflammatory medications (Aspirin, Rimadyl, Deramax, Meloxicam, Onsior, Piroxicam, Tendinap) - these medications decrease pain and inflammation.  There are some studies however that indicate they should only be used in the initial phases when active inflammation is present because these drugs do cause further cartilage degredation to occur.  Rimadyl, Meloxicam and Tendinap are the least likely to have negative effects according to a recent article. Some of these medications can cause issues with the kidneys, liver and gastrointestinal tract so it is important that you discuss use with your veterinarian and ensure that blood levels and stools are being monitored. (not commonly used in cats)

Opioids (Tramadol, Hydrocodone, Buprenorphine) - these medications are strictly for pain.  They can be given multiple times throughout the day and can help to keep your pet comfortable.  The side effects of these medications are drowsiness, dysphoria and constipation

Polysulfated Glycosaminoglycans (Adequan, Pentosan) - These medications allow us to treat the underlying pathology that is causing the arthritis to occur and are best use as early as possible in the course of disease.  They work by doing the following

1.  They stimulate the formation of cartilage matrix and increased production of proteoglycan by the chondrocytes.  Fibroblasts also increase production of hyaluronic acid when this medication is used as well.

2. The medication inhibits the release of the enzymes causing degradation.

3.  The blood flow to the joint and the bone under the cartilage is increased.

These medications are available through your veterinarian and are given as an injection once or twice a week for a period of time.  There are studies into the oral formulation to see if it is equally effective however the effects of the oral formulation appear to take longer and are not as potent as those seen with the injectable formulation.

Fish Oil (Omega 3 Fatty Acids) - These supplements are useful as anti inflammatory agents.  It is important however that the dosing be correct and that a reputable product be used.  Check with your veterinarian regarding which product would be best for your pet.

Glucosamine / Chondroitin - help the body to produce glycosaminoglycans and hyaluron in the joints.  Many products are available and it is very important that a reputable product be used.  Check with your veterinarian regarding which product would be best for your pet.

Green Lipped Mussel Extract - This is another anti inflammatory supplement that is having some positive effects for dogs with arthritis.  It is important that it also be purchased from a reputable source.  Check with your veterinarian regarding which product would be best for your pet.

As you can seen arthritis is a complex disease with lots of options for treatment.  To keep your pet comfortable and happy for years to come don't wait for the end stages of the disease starting them on supplements, weight loss and a good home exercise program in the early stages is the best course of action.  In some cases if you know your pet has an abnormally formed joint (hip dysplasia, elbow dysplasia, luxating patellas) then a visit with a rehab therapist before problems arise may delay the onset or prevent the development of arthritis as your pet ages.