Patient Education
Patellar Luxation
A kneecap that slips out of its groove — patellar luxation is common, often hereditary in small breeds, and very correctable when caught before arthritis takes hold.
The patella (kneecap) normally rides in a groove at the bottom of the femur (thighbone) and glides smoothly as the leg flexes and extends. Patellar luxation (PL) means the kneecap slips out of that groove — usually toward the inside of the leg (medial luxation) in small and toy breeds, or toward the outside (lateral luxation) in some large breeds and cats. When it slips, the dog often skips on three legs for a step or two until the kneecap pops back in. It looks alarming, but the dog often shows no pain in the moment. The real concern is long-term: repeated luxations erode the groove, stretch the joint structures, and accelerate arthritis. At Dog & Cat Hospital Calabasas, our surgical team grades each case and recommends intervention — or watchful waiting — based on what's best for that individual pet.
Signs & Symptoms
Patellar luxation presents differently depending on its severity (grade 1–4). Common owner observations include:
- Intermittent "skipping" — the dog lifts a hind leg for one to three steps, then continues normally
- Sudden three-legged lameness that resolves on its own when the kneecap pops back
- Sitting with the leg extended outward rather than tucked normally
- Persistent lameness or reluctance to use the leg in higher-grade cases where the patella stays out of the groove
- Audible or palpable click or pop when the leg is manipulated
- Gradual stiffness or exercise intolerance as arthritis develops over time
Grade 1 dogs may never visibly limp; Grade 3 and 4 dogs are lame most of the time. Cats with patellar luxation are often diagnosed incidentally during an exam.
Causes & Risk Factors
Patellar luxation is primarily a structural problem — the bony architecture of the leg doesn't guide the patella correctly:
- Genetics — strongly heritable in small breeds (Chihuahuas, Pomeranians, Toy Poodles, Yorkshire Terriers, French Bulldogs, Cavalier King Charles Spaniels)
- Shallow trochlear groove (the femoral channel the patella rides in)
- Tibial crest deviation — the bony bump where the quadriceps tendon attaches is positioned off-center, pulling the patella sideways
- Femoral or tibial angulation and rotation abnormalities
- Trauma — a direct blow to the knee can cause luxation in a previously normal joint, though this is less common than the hereditary form
- Larger breeds affected by lateral luxation often have concurrent hip problems
Does your dog skip a step on a hind leg?
Book an AppointmentHow We Diagnose It
Diagnosis is made by physical examination, graded by how easily the patella displaces and whether it returns to the groove on its own:
Orthopedic exam — The veterinarian feels the kneecap while flexing and extending the stifle (knee). A four-point grading system (Grade 1: occasional manual luxation, returns spontaneously; Grade 2: luxates with movement, returns spontaneously; Grade 3: usually luxated but reducible manually; Grade 4: permanently luxated and cannot be reduced) guides the treatment conversation.
Digital radiographs — X-rays evaluate the bony alignment of the femur and tibia, the depth of the trochlear groove, and the degree of existing arthritis. In larger or more complex cases, they help plan which surgical corrections will be needed.
Both legs are always assessed, since bilateral (both sides) luxation is common.
Treatment Options
Treatment decisions are based on grade, the pet's age and activity level, and the presence of concurrent problems like a cruciate ligament tear (which occurs in a meaningful number of dogs with Grade 3 or 4 PL).
Grade 1 — Most Grade 1 patients are monitored without surgery. Weight management, joint supplements, and regular rechecks to watch for progression are the standard approach.
Grade 2 — Surgery is often recommended for young, active dogs with Grade 2 luxation to prevent joint damage, though some clinically mild Grade 2 cases are managed medically. The decision is individualized.
Grade 3 and 4 — Surgery is the recommended treatment. The procedure for patellar luxation corrects the underlying structural abnormalities:
- Trochlear recession or block recession — deepens the femoral groove so the patella stays seated
- Tibial crest transposition — repositions the attachment point of the quadriceps tendon to realign the pull on the patella
- Soft-tissue imbrication or release — tightens or releases the joint capsule on either side to balance patellar tracking
Our surgical team performs these repairs in-house, and most small-breed dogs are walking on the leg within days.
When to See Our Calabasas Team
If your small dog occasionally skips or lifts a hind leg mid-walk, have it graded sooner rather than later. Early surgical correction — before the groove has been worn flat and before arthritis is established — gives the best outcome. Our surgical team in Calabasas can grade the luxation, take radiographs, and advise whether correction now or monitoring is the right call for your dog's grade and lifestyle. Book an appointment to get a grading and a clear recommendation.
Frequently Asked Questions
1My small dog skips on a back leg sometimes but seems fine otherwise — is that patellar luxation?
2Does patellar luxation in dogs always need surgery?
3What happens if patellar luxation is left untreated?
4Is patellar luxation surgery risky for small dogs?
5Can both kneecaps be luxating at the same time in one dog?
6How long is recovery after patellar luxation surgery?
7Can patellar luxation happen in cats?
8Will my dog develop arthritis even after the surgery?
Does your dog skip a step on a hind leg?
A quick orthopedic exam grades the luxation and tells you whether to monitor, treat, or correct surgically — before arthritis quietly adds to the problem.
Book an Appointment