In veterinary medicine, there are several orthopedic injuries or malformations that are very common. Some are treatable through medical management while others will need corrective surgery either by your general practioner or referral to a surgical specialist. When these occur there are generally several options for treatment or correction, this will be discussed with you by your general practioner. This page will discuss some of the more common orthopedic injuries and malformations seen in small animal veterinary practice and will give a overview of the information on each topic.
What is a Patella Luxation and Who is at Risk?
A patella luxation is the displacemnet of the knee cap (patella) either to the inside (medial) or the outside (lateral) of the knee. There are several different degrees of this condition and can be classified as grades I through IV. This condition is considered one of the most common stifle abnormalities in dogs, with greater then 75% being medial and 50% being bilateral (or both sides involved). Many different breeds can be affected with toy and miniature breeds being more common. Females are also slighly more at risk for this disorder.
What Causes a Patella Luxation?
The muscles of the thigh attach to the knee cap and then continue down through the patella ligament to attach to the upper tibia. When the thigh muscle contract they then lift the tibia to straighten the leg. The patella is supposed to stay in the middle of the knee through this course of action. But if the attachment of the patella ligament is too far to the inside or the outside on the tibia then the patella will be pulled out to that side. This action wears down the ridge that keeps the patella in the middle of the lower femur and eventually the patella will luaxate (i.e. "popping out") to that side of the joint. Once this occur the process becomes easier and ends up becoming a chronic problem.
Figure 1 - Normal Patella presentation
Figure 2 - Medial Luxation
Figure 3 - Lateral Luxation
Does a Luxating Patella cause Long term problems?
Some pets can tolerate this problem for many years, if not thier entire lives. However, this will weaken the knee and predisposes the knee to many other injuries, especially torn criciate ligaments. With advancing age, arthritic changes may take place in the joint, causing long term pain.
How are Laxating Patellas Corrected?
Early on in the process many pets can be medically managed with anti-inflamatories and supportive product for joint health (ask what you veterinarian recommends), but surgery should be preformed if your dog has persistent pain or lameness or if other knee injuries occur due to the luxating patella. There are several different surgical techniques for correction of this condition and will be decided upon by the veterinarian doing the procedure. If the surgery is preformed before arthritis occurs, the prognosis is excellent and the pet should regain full use of their leg. However, if athritis has occured then often intermittent pain will arrise and anti-inflammatories will be needed to ensure your pet remains pain free.