However, not all kneecap movement during examination means a dislocation that causes symptoms. Some sideways mobility of the kneecap can be normal in cats. The finding's significance is assessed in relation to limping, pain and examination of the whole hind limb. A hop observed at home does not confirm the diagnosis either.
When to see a vet urgently
Arrange an examination for a limping cat, and seek urgent care if any of these signs occur:
- no weight placed on a hind leg at all;
- sudden hind leg symptoms with severe pain;
- inability to stand or dragging the hind legs;
- limping after a fall or road traffic accident;
- an obvious wound or rapidly increasing swelling in the leg.
Do not try to push the kneecap back into place. You can find a vet near you.
Overview
The kneecap plays an important role in the mechanics of hind leg movement. Normally, it glides securely in the groove between the femoral condyles. In patellar luxation, it moves out of this groove, disrupting knee function. Cats can have congenital forms, more often in breeds with limb abnormalities, or acquired forms following injuries or joint disease.
In medial luxation, the kneecap moves to the inside of the knee; in lateral luxation, it moves to the outside. These terms describe direction, rather than pain severity. Both knees need examination because the condition may affect both sides. Asymmetry in a cat's movement does not always show which side is more painful.
Knee function involves the thigh muscles, tendons, ligaments and bone alignment as well as the kneecap. Examination therefore establishes whether the primary problem is kneecap tracking or a broader injury or structural abnormality. Hip disease can also cause hind leg symptoms.
Causes
- Congenital limb development abnormalities, including abnormal shape of the thigh bone or shin bone.
- Injuries from falls, blows or road traffic accidents.
- Knee ligament problems.
- Osteoarthritis and degenerative changes.
Osteoarthritis accompanying luxation is often a consequence of abnormal loading of the joint surfaces. Finding osteoarthritis alone therefore does not establish that it originally caused the kneecap to move. After an injury, concurrent bone and soft tissue damage may need assessment; a previous luxating patella does not automatically explain new limping.
Risk factors
- Breed predisposition: it has been described in Devon Rex and Abyssinian cats; luxation is usually medial, towards the inside, and often affects both knees.
- Young cats with congenital abnormalities.
- Active cats at high risk of injury.
- Older cats with degenerative joint disease.
Information on the size of breed-, age- and activity-related risks in cats is limited. The condition also occurs in non-pedigree cats, and an active life alone does not cause it. A previous thigh bone fracture or knee surgery in the same limb may affect the risks of later corrective surgery. This history is useful in treatment planning even if the injury is old.
Typical symptoms
- sudden or chronic hind leg limping;
- a skipping gait: the cat walks normally, then holds the leg up for a few steps before bearing weight again;
- pain on movement;
- instability and reluctance to jump;
- displacement of the kneecap out of its groove when examined by touch.
At home, signs may also include avoiding stairs, getting up more slowly or changing usual jumping routes. Your cat may choose a lower resting place or stop playing partway through. Describe these changes to the vet even if walking appears normal at the appointment.
Displacement of the kneecap on palpation is a veterinary examination finding, rather than a test for you to perform. Repeatedly bending the knee or pushing the kneecap does not help assess pain at home. Sudden limping may also result from claw damage, a bite abscess, fracture, cruciate ligament injury or impaired circulation. These cannot be distinguished from a skipping gait alone.
Complications and consequences
- chronic knee instability;
- progression of osteoarthritis;
- persistent limping;
- wasting of the limb muscles;
- reduced activity and quality of life.
The likelihood of complications varies according to findings and symptoms. Minor mobility without symptoms does not mean severe osteoarthritis is inevitable. Conversely, a luxation classified as mild can cause considerable limping. Function and pain therefore cannot be judged from the luxation grade alone.
Diagnosis at the vet
- an orthopaedic examination and palpation of the knee;
- hind leg X-rays to assess bone abnormalities and osteoarthritis;
- ultrasound or CT for more detailed assessment of ligaments and cartilage;
- grading the luxation from I to IV.
The initial examination includes watching the gait, feeling both hind limbs and locating pain. The vet also assesses muscle mass, knee stability and findings in other joints. A sore or tense cat may need sedation so that examination and correctly positioned X-rays can be performed safely.
Ultrasound or CT is not a routine confirmation test for an ordinary luxating patella. Diagnosis relies particularly on the orthopaedic examination. CT may provide more information on bone shape when planning surgery for a severe structural abnormality. An appropriate test is selected to assess ligaments and cartilage, rather than using the same imaging package for every cat.
What do grades I–IV mean?
The grading system describes how easily the kneecap moves out of place and whether it returns. In grade I, it returns by itself when sideways pressure applied during examination is released. In grade IV, it is permanently displaced and cannot be returned manually to its normal groove. Intermediate grades vary in how it returns and stays in place. Normal feline mobility is distinguished from true luxation.
Grading supports planning, but treatment decisions also depend on symptoms. A short home video of normal walking or stair use can complement observations at the practice. Film the whole cat and movement sequence in good light. Do not, however, force a painful cat to jump for a video.
Treatment
When may monitoring be enough?
Not every cat needs surgery. With few symptoms, movement can be monitored, pain managed and daily life adapted. The vet assesses suitable medication according to other illnesses and test results. A painkiller may relieve symptoms but does not change bone alignment or permanently correct mechanical instability.
Maintaining a healthy weight reduces joint loading. Any weight loss is planned individually; do not fast your cat. A joint supplement should not replace prescribed pain relief: evidence for supplements in feline osteoarthritis is limited. Do not give human painkillers, as ibuprofen, for example, can be life-threatening to cats.
When is surgery considered?
Persistent or recurrent limping that limits function, clear pain and severe luxation may support correction. The aim is to make the kneecap track in a functional line and stay in its groove. Surgery may alter the soft tissues guiding the kneecap, the femoral groove or the direction of the patellar tendon attachment. The technique is selected according to the knee's structure.
Surgical results in cats can be good, but complete freedom from symptoms cannot be promised. Possible problems include recurrent luxation, implant-related complications and the need for further surgery. Previous fractures and operations, as well as severe luxation, are considered in risk assessment. Canine success rates cannot be applied directly to a cat's prognosis.
Recovery at home
After surgery, activity is restricted according to the surgeon's plan. A cat may be able to jump onto furniture before repaired tissues are ready to withstand the load. Return to unrestricted movement is agreed according to check-ups and, where needed, X-rays assessing healing.
Make food, water and resting areas easy to reach, and use a litter tray with low sides. Follow wound or dressing care instructions and report increasing lameness, swelling or discharge. Knee bending, heat or cold therapy and rehabilitation exercises should start only with individual instructions. Their intensity should not be based on a brief improvement in walking.
Follow-up also assesses daily life
Record whether normal walking, using stairs and entering the litter tray become easier. Monitoring the same daily activities helps assess treatment response. Persistent limping does not always mean another dislocation: other joints, pain and the stage of recovery are also assessed. Worsening or suddenly returning symptoms need assessment before the planned check-up.
Prevention
- Do not breed cats with orthopaedic abnormalities.
- Prevent injuries through a safe environment indoors and outdoors.
- Keep your cat at a healthy weight, as obesity increases joint loading.
- Arrange regular veterinary checks for a cat of a predisposed breed.
Important for cat owners
A luxating patella may cause only slight limping, but untreated it leads to chronic pain and osteoarthritis. Remember that if your cat occasionally hops on three legs or avoids jumping, have it examined by a vet experienced in orthopaedics. Early detection and surgery for severe forms help maintain activity and a good quality of life.
However, not every minor untreated finding progresses in the same way. Assessment distinguishes a finding suitable for monitoring from disease causing pain and loss of function. Treatment needs are reviewed if movement or behaviour changes.
This article provides general information and does not replace veterinary care. If you notice signs of illness in your cat, contact a vet.
Frequently asked questions
Does every luxating patella need surgery?
No. Decisions depend on the amount of pain and limping, function, severity of the finding and other illnesses. A cat with no or few symptoms can sometimes be monitored. Persistent or worsening symptoms need reassessment even if the grade is mild.
Can I try putting the kneecap back myself?
Do not try. Handling the knee can cause pain, and a home test cannot distinguish normal mobility from another problem. The vet examines the kneecap, knee stability and the rest of the limb. At home, it is more useful to observe when limping occurs.
Can a cat limp even if the X-ray looks fairly normal?
Yes. Pain and function are also assessed through examination and observations at home. The extent of changes on an image does not always match pain severity. X-rays help assess bone and osteoarthritis but do not replace an overall assessment.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
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- Patellar Luxation (Dislocating Kneecap) in Dogs, ACVS, accessed 2026-11-03.
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- Chronic Pain Assessment in Cats, AAHA, accessed 2026-11-03.
- Arthritis in Cats: Signs, Treatment & Care, Cats Protection, accessed 2026-11-03.
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