A luxating patella (kneecap) is a common orthopedic abnormality in small or toy breed dogs, though it can occur in large breeds, as well. The patella normally sits in a groove of the femur (thigh bone). In dogs with a luxating patella, the patella shifts in and out of that groove, most commonly moving to the inside of the knee; this is referred to as a medial luxating patellae. In severe cases, the patella may become “stuck” in an abnormal position either to the inside or outside of the knee. Some dogs have only one patella that luxates, while others are affected bilaterally (both kneecaps luxate).
Dogs in which one or both patellae intermittently luxate often show episodic lameness or limping. Pet families often note that their dog exhibits a skipping gait. These dogs may hold the affected leg up when the patella moves out of its normal position and begin using the leg normally again when the patella moves back into its normal position. Dogs with patellae that are permanently stuck in an abnormal position may have more significant limping or lameness.
A veterinary surgeon is best able to diagnose a luxating patella. Further, a surgeon can grade the severity of patella luxation and make treatment recommendations. Low-grade patella luxation may be amenable to medical management, which may include maintaining an ideal body weight and intermittent courses of an anti-inflammatory medication. Higher grade patella luxations often require surgery.
Pending further evaluation by a veterinary surgeon, any pet with limping or lameness should be kept activity restricted to decrease further exacerbation of inflammation and injury. Pets should be restricted to short (10-15 minute) leash walks to use the bathroom and should not be permitted to run, rough-house, play, or jump on furniture. Steps should be minimized to decrease the risk of falling and acquiring a new or worse injury.