Luxating Patella in Dogs: Grades, Symptoms, Treatment, and Surgery

What Is a Luxating Patella in Dogs?

A luxating patella in dogs is a kneecap that slips out of its groove at the end of the thigh bone, and the classic sign is a dog that suddenly skips on one back leg for a few steps. Treatment depends on the grade, which vets score from 1 to 4.

Patellar luxation is one of the most common orthopedic conditions in dogs, according to the American College of Veterinary Surgeons (ACVS), and it mainly affects small and toy breeds. Mild cases often need only monitoring and home care, while higher grades usually need surgery to keep the kneecap in its groove.

The knee joint connects the femur (thigh bone) and the tibia (shinbone). The kneecap, or patella, normally sits in a groove at the end of the femur called the trochlear groove, VCA Animal Hospitals explains, and with a luxating patella it moves out of that position.

ACVS describes patellar luxation as the kneecap riding outside the femoral groove when the knee bends: medial when it rides on the inner side of the knee, lateral when it rides on the outer side.

Treatment depends on the grade and on how much the dog favors the leg. For many mild cases, home care focuses on a healthy weight and less strain on the knee, and Oakland Veterinary Referral Services advises avoiding repeated jumping from furniture and using ramps or steps instead.

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Symptoms of a Luxating Patella in Dogs

The main symptom of a luxating patella in dogs is a skipping gait: the dog suddenly runs on three legs for a few steps with one back leg held up, then carries on normally. Cornell University's Riney Canine Health Center calls this skip the most commonly seen sign.

The signs of luxating patella in dogs are skipping, holding a back leg up, sudden lameness, and in severe cases a bow-legged stance. In grades 1 and 2, the Orthopedic Foundation for Animals (OFA) notes, a dog limps only while the kneecap is out.

At home, a luxating patella looks like:

• Skipping or hopping for a few steps on one back leg
• Holding a back leg up, then using it normally again
• Kicking the leg out to the side or stretching it backward, which can pop the kneecap back into place
• A bow-legged or crouched stance with the feet turned in, in more severe cases
• Avoiding stairs or showing signs of knee pain

Many dogs with medial luxation learn to kick the leg out to the side, VCA explains, which snaps the kneecap back into place. Over time the soft tissues around the joint stretch, and the kneecap pops out more easily.

Puppies with severe medial luxation often look bow-legged, a shape that worsens with growth, ACVS says, and OFA notes that dogs with grade 3 or 4 shift most of their weight onto the front legs.

A limp alone does not confirm a slipping kneecap; our guide to why a dog is limping covers other causes.

Do dogs with luxating patella feel pain?

A luxating patella does not always hurt, but pain becomes more likely as it progresses. ACVS says mildly affected dogs are often not in pain, while the condition can become quite painful later. OFA links pain to damaged cartilage on the kneecap and femur, though most dogs show little discomfort when the knee is handled.

Much of the longer-term pain comes from arthritis, because frequent slipping wears away the joint cartilage. VCA lists prescription anti-inflammatories, antibody therapy, joint supplements, and therapeutic mobility diets as options that may slow arthritis and help control discomfort.

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The Four Luxating Patella Grades

The four luxating patella grades run from an occasional slip to a kneecap that stays out: grade 1 slips out only when pushed, and grade 4 stays out of the groove and cannot be pushed back. Vets assign the grade during a hands-on exam, and it guides treatment along with how the dog uses the leg.

This luxating patella grade table matches each of the four grades to what the vet feels, what the owner sees at home, and the usual treatment, including whether surgery is usually advised.

Grades also come with a direction, and one or both knees can be involved:

• Medial: the kneecap slips toward the inside of the knee. A board-certified surgeon's conference slides, hosted by the University of Illinois College of Veterinary Medicine, put medial patellar luxation at 80 to 90% of cases.
• Lateral: the kneecap slips toward the outside of the leg. VCA says dogs with a laterally luxating patella are often medium or large dogs.
• Bilateral: both knees are affected, sometimes at different grades. VCA says approximately half of affected dogs have bilateral luxating patellas.

A mild luxating patella in dogs, grade 1 or a grade 2 with little or no limping, is usually managed without surgery. The Merck Veterinary Manual reserves conservative care for these dogs, older dogs, and dogs that cannot have surgery, and recommends surgery for grades 2 to 4, marked lameness, or worsening signs.

Grade alone does not settle the decision: two veterinary orthopedic authors in Vet Times argue it should rest on the dog's pain, the type and duration of lameness, and how well the leg works.

Breeders may meet a second scale: OFA's registry grades by bone deformity, so its grades differ from the clinic grades VCA and Merck use.

What Causes a Luxating Patella, and Which Dogs Get It?

A luxating patella is usually caused by the way the back leg forms and lines up during growth, and less often by an injury to the knee. Because the kneecap sits in the knee of the back leg, the condition affects the back legs, not the front legs.

The causes of a luxating patella in dogs are inherited limb alignment, a shallow groove, and injury, and more than one can be at work in the same dog. ACVS says most cases come from a growth disorder with abnormalities that may be present at birth, though the precise cause is unclear in most dogs and likely multifactorial.

• A shallow groove: the femoral groove the kneecap rides in is commonly shallow or absent in affected dogs.
• Inherited limb alignment: ACVS now sees developmental luxation as part of a limb-wide problem, including an abnormal hip such as hip dysplasia and a malformed femur and tibia.
• Injury: knee trauma occasionally causes it, with sudden, severe lameness in a dog that had no problems while growing.

The condition runs in families. OFA says the deformities behind it are present at birth and calls it an inherited disease, and a 2018 Swedish Kennel Club study found it in 23% of the Chihuahuas studied, with an estimated heritability of 0.25.

Toy breeds are the dogs most affected, plus a growing number of large breeds that get it. ACVS says the condition affects primarily small dogs, and VCA notes a genetic predisposition to medial luxation in many toy and small breeds. ACVS adds that cases in large breed dogs have risen over the past ten years.

In a VetCompass study of 210,824 dogs at 119 English primary-care clinics, 1.30% had a diagnosed patellar luxation, and Chihuahuas had 5.9 times the odds of a diagnosis compared with crossbred dogs. ACVS reports a figure of 7% in puppies, a different group.

How Vets Diagnose a Luxating Patella

Vets diagnose a luxating patella by feeling the knee during an orthopedic exam to see whether the kneecap moves out of its groove, then grading it from 1 to 4. Diagnosis is by knee palpation, with X-rays to check the bones of the leg and look for other joint problems.

ACVS says the diagnosis rests essentially on palpation of an unstable kneecap. A 2018 University of Naples review describes the test: the vet holds the kneecap between thumb and index finger, extends the leg, and twists the foot inward to check for medial luxation or outward for lateral luxation.

A full work-up for diagnosing luxating patella in dogs can include:

• Watching the dog walk, since a dog may stretch the leg backward to reseat a slipped kneecap, the Naples review notes
• Feeling each knee and assigning a grade from 1 to 4, which Cornell says helps guide treatment
• X-rays of the knee, pelvis, and shinbones, which VCA and ACVS describe for judging the extent of the problem, checking bone shape, and looking for hip dysplasia
• CT or MRI in some cases, according to Cornell

The skip you notice at home is a reason to book an exam, not a diagnosis; confirming a slipping kneecap and its grade takes the vet's hands-on knee exam.

Luxating Patella Treatment Without Surgery

Treatment without surgery for a luxating patella in dogs means weight control, exercise changes, physical rehabilitation, and pain relief, and it suits mild cases best. Cornell says most mild cases without clinical signs need no treatment, while dogs with occasional lameness or arthritis from the luxation may need conservative management that includes:

• Keeping the dog at an ideal weight
• Joint supplements
• Pain medication such as nonsteroidal anti-inflammatory drugs (NSAIDs)
• Exercise restriction
• Physical rehabilitation

Joint supplements are one piece of that plan. One glucosamine and chondroitin option is Nutramax Dasuquin Chewable Tablets for Small/Medium Dogs Under 60 lb, 84 count; its maker lists 600 mg of glucosamine hydrochloride and 250 mg of chondroitin sulfate per tablet and says to allow 4 to 6 weeks to note a response. Our Cosequin vs Dasuquin comparison explains how the two differ.

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The Naples review calls weight control essential to reduce stress on the knee, uses rehabilitation exercises to strengthen the quadriceps mechanism in the thigh, and relies on NSAIDs, alone or with other painkillers, for pain. Prescription NSAIDs such as carprofen are given under a vet's direction.

Conservative care eases pain and inflammation, but it does not put the kneecap back in place permanently. Merck says it leaves the underlying anatomy uncorrected, so the luxation can still progress, and Vet Times authors note limited long-term outcome data.

How to treat luxating patella in a dog?

Treat it according to the grade and how the dog uses the leg. Dogs with no signs are monitored. Dogs with mild, occasional lameness get weight control, controlled exercise, rehabilitation, and vet-prescribed pain relief. Surgery is most often considered from grade 2 up, ACVS says, and Merck adds marked lameness or worsening signs as reasons to operate.

Can a dog live with luxating patella without surgery?

Yes, many dogs do. VCA says some dogs, especially with grade 1, tolerate a luxating patella for many years or even their whole lives, and OFA says many dogs with grade 2 live reasonably well for years. The tradeoff is joint wear: VCA notes that arthritis develops as these dogs age and cannot be reversed.

Living well without surgery depends on everyday footing as well as medicine. Oakland Veterinary Referral Services lists trimmed nails, non-slip rugs or runners, controlled and regular exercise, and avoiding sudden increases in activity among its home supports for these dogs.

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Luxating Patella Surgery: Recovery and Cost

Luxating patella surgery in dogs realigns the pull on the kneecap and deepens its groove so it stays in place. For owners, surgery means one or both of two bone procedures (groove deepening and tibial tuberosity transposition), a recovery of at least 6 weeks of restricted activity, and a cost that pet insurers put in the thousands of dollars per knee.

The two main procedures, as VCA describes them:

• Tibial tuberosity transposition: moving the point where the patellar ligament attaches to the shinbone to its proper location, which Merck says realigns the quadriceps mechanism.
• Trochleoplasty: deepening the groove in the femur where the kneecap glides, so it is harder for the kneecap to slip out.

VCA says surgery may be recommended sooner rather than later to reduce the chance of arthritis or a cruciate ligament tear, and the higher the grade, the sooner. The Vet Times authors differ for dogs that are not lame: citing a 1992 study, they say sound dogs are likely not to benefit, because joint degeneration progresses similarly anyway.

Recovery needs at least 6 weeks of restricted activity because the surgery cuts and repositions bones that must heal, Southwest Veterinary Surgical Service explains. Hospital aftercare plans lay out luxating patella surgery recovery week by week:

• Weeks 1 to 6: short, slow leash walks, starting at 5 to 10 minutes 2 to 3 times a day at the Animal Clinic of Billings and increased gradually. MedVet allows no off-leash time, running, jumping, play, flights of stairs, or slippery floors.
• Weeks 1 to 8: the Naples review restricts activity for 6 to 8 weeks and adds rehabilitation exercises for range of motion, strength, posture, and flexibility.
• Week 8: if all is going well at the recheck, the Billings clinic typically lifts most limits except ball play, rough-housing, and off-leash activity.
• Weeks 10 to 12: all restrictions are typically lifted.

Weighing the pros and cons of luxating patella surgery:

• Pro: over 90% of owners are satisfied with their dog's progress, ACVS reports, and MedVet expects success, a return to normal or near-normal activity, in more than 90% of patients.
• Con: in a 2006 series of 109 dogs, 18% had a complication, 13% needed revision surgery, and 8% had the kneecap slip out again, with more problems in dogs of 20 kg or more and in higher grades.
• Con: in a 2024 study of dogs under 10 kg, minor complications affected about 46% of dogs, and the kneecap slipped out again in about 19%.

Problems after luxating patella surgery include the kneecap slipping out again, loose or broken implants, and fractures near the top of the shinbone, Vet Times authors list. Southwest Veterinary Surgical Service calls the prognosis generally good for most grade 2 and 3 luxations and more guarded for grade 4.

How much does luxating patella surgery cost for a small dog?

Pet insurers put the surgery at about $1,000 to $5,000 per leg, according to MetLife Pet Insurance, or $1,500 to $3,000 per affected knee with a board-certified surgeon, according to Embrace Pet Insurance. These are insurer estimates, and clinic quotes vary.

MetLife says the price depends on the dog's size, the severity, other injuries or arthritis, location, and whether one or both knees need surgery. Vet Times authors add that higher grades often mean more complex surgery and higher costs.

For dogs that need regular pain medication or supplements, Embrace puts the typical cost at about $20 to $50 a month.

Exercise and Home Care for a Luxating Patella

Exercise and home care for a luxating patella aim to keep the knee moving without sudden strain. Daily care has two parts, walking and home care: short leash walks, ramps or steps instead of jumping, and traction on smooth floors, set to your vet's advice.

VCA suggests these changes at home for dogs with mobility problems:

• Lay non-slip rugs or runners without raised edges along your dog's usual routes, and wherever it still jumps on or off furniture.
• If your vet says furniture is still safe, teach your dog to use stairs or a ramp made for pets. Our best dog ramps guide compares ramps, and the Pet Gear Easy Step Dog & Cat Stairs, Small are one set of pet steps.
• Add grip with nail caps, pad coverings, or boots, after asking your vet or a rehabilitation therapist which suits your dog. Dr. Buzby's ToeGrips Dog Nail Grips, 20 count, Small are made for dogs that slip on smooth indoor floors, though a published gait study of them used healthy dogs.
• For more support, see our guide to mobility aids for dogs, from harnesses to ramps.

Physical therapy for a luxating patella, often called physio, centers on exercises that build the quadriceps, the Naples review says. Massage, home remedies, and natural treatments do not put the kneecap back in its groove for good, since Merck notes that non-surgical care leaves the underlying anatomy uncorrected. Ask your vet or a rehabilitation therapist before adding them.

Preventing the inherited form is a breeding matter, since the deformities behind it are present at birth. For a dog that already has a luxating patella, the goal is to prevent extra strain with a lean weight, no repeated jumping, and steady exercise.

Is it okay to walk a dog with luxating patella?

Yes, with short, controlled leash walks. Cornell's arthritis guidance lists leash walks and swimming as low-impact activities, and VCA says the vet sets the level of exercise restriction, which can range from complete rest to brief walks around the block, so ask your vet how far and how often.

Long-Term Outlook: Arthritis and Cruciate Risk

The long-term outlook is often good in mild cases, but the main long-term risks are arthritis plus a cruciate ligament tear. ACVS explains that frequent slipping erodes cartilage and exposes bone, causing arthritis and pain, and strains the knee in ways that may predispose it to a ruptured cranial cruciate ligament.

In a 2010 study of 162 small-breed dogs with medial luxation, 41% also had a cranial cruciate ligament rupture, and those dogs averaged 7.8 years old versus 3.0 years for luxation alone. That injury is often called a torn ACL in dogs.

With or without surgery, many dogs with more severe luxation or persistent signs may develop arthritis that requires medical management, Cornell says; see our guide to osteoarthritis in dogs and its signs.

Do luxating patellas get worse with age?

They can. Cornell says patellar luxation may progress over time, causing more frequent bouts of lameness, and a luxating patella does not heal or correct itself. In older dogs with grade 1 or 2 luxations, OFA says sudden lameness can appear as the soft tissues break down after minor trauma or as arthritis pain worsens.

Size matters too: VCA says dogs with lateral luxation, often medium and large dogs, tend to have more mobility problems. Our article on whether size matters for a dog with arthritis covers that side.

What happens if luxating patella is left untreated?

It depends on whether the dog has signs. Cornell says dogs without significant signs generally have a good prognosis and can be managed comfortably for many years. For a dog already showing knee problems, MedVet says the signs generally progress, with a steady loss of limb function, muscle loss, and a worse grade of luxation.

When to See a Vet

See a vet if your dog skips, limps, holds up a back leg, avoids stairs, or shows signs of knee pain, Oakland Veterinary Referral Services advises. Sudden or severe signs need more urgent care.

If surgery is on the table, a Cornell surgeon urges owners of dogs with orthopedic problems to seek care from a Diplomate of the American College of Veterinary Surgeons.

Luxating Patella in Dogs FAQs