Health Articles

Patella Luxation  (Dislocated Knee)

by Anne Jones RN, BSNE

 
The most common orthopedic problem found in the Bichon Frise is patellar luxation, which can lead to rupture of the cruciate ligament. Occasionally Bichons can suffer hip dysplasia , but this condition occurs more often in large breeds, while patellar luxation is more common in small breeds, as is Legg-Calve-Perthes Disease.

The patella is the kneecap, part of the structure of the stifle (knee) joint. A patella that is not stable but does not slip out of joint is said to be subluxating, while one that comes out of joint on its own is said to luxate. The cause of the problem can be from trauma but is more often genetic in nature. When the luxation is from trauma, something has occurred that has caused the knee to be forced out of normal alignment. A veterinary examination can determine if the knee structure is stable but an overzealous examination can stretch the ligaments. This type of examination is best left to the veterinarian and not done by the pet owner! Usually the traumatic injury occurs when the dog’s leg gets caught somehow and he struggles to pull free. Or during an overly enthusiastic playtime when the playmate grabs the foot and holds tight while the excited puppy tries to get away. Any other similar accident can permanently injure this small joint.

When the luxation is of a genetic nature, it is due to an abnormal development of the leg. There is a small groove that is a part of the structure that allows the patella to move freely but still remain in proper alignment. When this groove is too shallow or when the leg is slightly bowed, the ligaments holding the patella can be damaged. The ligaments themselves can be weak. Any or all of the above will lead to problems.

Signs of patella luxation are limping, pain, and the dog may frequently stop to stretch his rear leg behind him. This straightening of the leg is done to allow the patella to pop back into its normal groove. There are several degrees of luxation, with the lower grade being the ability of the kneecap to pop back into place on its own and the highest grade (of four) being such severe luxation that only surgical repair can correct the dislocation. There are numerous reports of rupture of the anterior cruciate ligament. This term is familiar to any sports fan! Many a losing season can be blamed on injury to a key player’s ACL!

If your dog has subluxating patellas, by all means keep his weight down. The obese dog will surely only become worse. When the patella(s) become loose enough to pop in and out, surgery is usually indicated. Obviously in Grades 3 and 4, surgery will be a necessity. The surgery will include deepening the groove in the thigh bone that the kneecap rides in. Recovery may take at least 6 weeks and may include physical therapy.

Following surgery, your dog may be given pain medication. One product for pain is the pill Rimadyl. There have been reports that suggest that some Bichons develop liver toxicity on this drug, so he will need close observation for signs of liver disease. If the pain is not severe, omit the medication altogether. Obviously the dog must avoid running, jumping, and active play during recovery and should be crated when not under close supervision. Walk him on his leash and limit outside time to the few minutes necessary to relieve himself. He should be carried and not allowed to walk up and down steps. Watch for signs of infection and keep the bandage dry. If he wants to chew the bandage, check for problems and consider using an Elizabethan collar or restrict his ability to reach the knee bandage by securing a folded hand towel around his neck. This “thick collar” will allow him to move around without the weight of an Elizabethan collar but he will not be able to get his mouth on the surgical area.

Remember that repetitive dislocation of the patella will only worsen the condition and that arthritis may occur. The surgery should not be dangerous for an otherwise healthy dog and permanent repair means an active life for your pet for years to come. Keeping that weight down to a normal level on any dog with signs of patellar luxation may enable him to avoid damage in the first place. It will certainly make for faster healing if he ever does need surgery.

 

This material has been gathered from a number of canine health publications, including:
“Canine Terminology”, Spira
“Dog Owners Veterinary Handbook”, Carlson, DVM, and Giffin, MD
“Your Dog”, published by Tufts University Veterinary School