Patellar Luxation Grades 1 to 4: What Each Stage Means for Your Dog
The four-grade scale describes how easily a dog’s kneecap slips out of place, and it frames—though never settles by itself—the question of when surgery enters the conversation.
The skipping little hop—three steps on four legs, then a stride on three—is often the first sign owners notice. In small breeds especially, a kneecap that slides out of its groove is one of the most common orthopedic findings veterinarians encounter, and the condition is graded from 1 to 4 during a hands-on exam. That number describes mechanics, not destiny.
Because grading is a hands-on judgment, it belongs in an in-person veterinary exam. A veterinarian feels how far the kneecap moves, whether it returns on its own and how the leg is aligned, sometimes adding X-rays to assess the bones. Two dogs with the same grade can live very different lives, which is why the grade starts the conversation about treatment rather than ending it.
What the four grades actually describe
Grade 1 means the kneecap can be pushed out of its groove by hand but snaps back on its own; grade 2 means it slips out at times during normal movement and returns when the leg is repositioned or on its own. Grade 3 describes a kneecap that sits out of the groove most of the time but can still be pushed back, and grade 4 one that stays out and cannot be manually replaced. The higher the grade, the more the surrounding bones and soft tissues have usually adapted around the abnormal track.
Grades can shift over a dog’s lifetime, usually upward, as cartilage wears and tissues stretch. That is why veterinarians recheck the knee at routine visits and ask owners to report new skipping, stiffness after rest or reluctance to jump. A grade recorded at age two is a data point, not a permanent label, and individual variation in how fast knees change is considerable.
Living with grades 1 and 2
Many dogs with grade 1 and some with grade 2 luxation show few symptoms and are managed without surgery. The pillars are unglamorous: keeping weight lean, building thigh muscle with steady walks, limiting repeated jumps off furniture, and using rugs or ramps on slippery floors. These measures do not straighten the kneecap’s track, but they reduce the load that drives wear.
Watchful management still has rules. Painkillers or joint supplements should be chosen with a veterinarian, since every medication carries its own possibility of side effects and complications. And a symptom list marks the exits from watch-and-wait: limping that lasts more than a day or two, crying when the knee is touched, a leg held up more often, or sudden refusal to bear weight—see a veterinarian.
When surgery enters the conversation
Surgery is discussed most often for dogs with persistent lameness, for grade 3 and 4 knees, and for young dogs whose bones are still deforming around a badly tracking kneecap. The operation typically combines deepening the groove, realigning the tendon attachment and tightening soft tissues, tailored to each knee. An untreated high-grade knee also strains the cruciate ligament, which is part of why surgeons prefer not to wait until the joint has fully remodeled.
Owners weighing surgery should plan for the recovery period as seriously as the operation: weeks of restricted activity, controlled leash walks and often rehabilitation exercises before normal play resumes. As with any orthopedic procedure, complications are possible—implant irritation, infection or re-luxation among them—and outcomes differ between individual dogs. The decision comes out of a structured conversation with a veterinarian about this dog’s grade, symptoms, age and lifestyle, not a formula read off a chart.
Before your vet visit
- Take a phone video of the skipping gait to show the veterinarian.
- Note when limping appears—after rest, after play or on stairs.
- Record your dog’s weight history and current food portions.
- List past knee diagnoses, grades and any medications tried.
MediIndex articles are for general information only and are not medical advice, diagnosis, or advertising. Outcomes vary by individual — consult a board-certified specialist for personal decisions.
