Knee osteoarthritis: symptoms, causes and treatments

Gonarthrosis is the medical term for knee osteoarthritis. This chronic condition affects more than cartilage: as it develops, the bone underneath the cartilage, the synovial membrane and other joint tissues may also change. It can affect one knee or both, and different areas of the joint.

Pain often occurs when the knee is used, such as during walking, climbing stairs or standing for a long time. Some people experience occasional discomfort, while for others mobility gradually becomes more difficult. Understanding the affected area, the symptoms and contributing factors helps explain how knee osteoarthritis is assessed and managed.

What is gonarthrosis?

Gonarthrosis is osteoarthritis of the knee joint, where the thigh bone (femur), shin bone (tibia) and kneecap (patella) meet. Cartilage normally helps the joint surfaces glide smoothly. In osteoarthritis, cartilage changes and may gradually become thinner, but the disease is not simply “wear and tear”: subchondral bone, the synovial membrane and other structures may be involved.

The condition is chronic but does not necessarily progress steadily. Relatively stable periods may alternate with more painful episodes, sometimes accompanied by knee swelling. Age increases the likelihood of osteoarthritis, but normal ageing alone does not explain it. Mechanical, metabolic, anatomical and injury-related factors can all contribute.

What are the symptoms of knee osteoarthritis?

The most familiar symptom is knee pain, also called gonalgia. It is often mechanical in nature: discomfort increases when the joint bears weight or moves, and improves with rest. Walking, standing, exercise, carrying heavy objects and using stairs may make it more noticeable.

Stiffness after inactivity, particularly on getting up in the morning, can also occur; morning stiffness in typical osteoarthritis is generally relatively brief. Some people experience cracking sensations, catching, occasional locking, a feeling that the knee might give way or reduced movement.

These symptoms are not exclusive to osteoarthritis. Meniscal problems, ligament or tendon injuries, trauma and other joint conditions can produce similar signs.

Can gonarthrosis cause a swollen knee?

Yes. Knee osteoarthritis may include episodes of increased joint irritation, sometimes described as inflammatory or congestive flares. Pain may intensify rapidly, become noticeable at rest or overnight, and be accompanied by fluid within the joint, swelling and greater stiffness.

However, do not automatically attribute new swelling to osteoarthritis. Inflammatory, traumatic and infectious causes are also possible. Seek medical advice for new or significant swelling, especially with unusual pain, fever or marked difficulty bearing weight.

What is the difference between tibiofemoral and patellofemoral osteoarthritis?

The knee contains several joint compartments. Tibiofemoral osteoarthritis affects the meeting point of the femur and tibia; patellofemoral osteoarthritis affects the area between the femur and kneecap. The location matters because certain movements place greater demands on one compartment than another.

What is tibiofemoral osteoarthritis?

This form affects the surfaces between the femur and tibia. It is the most common knee location. French National Health Insurance (Assurance Maladie) reports that it accounts for approximately 45–50% of cases of gonarthrosis, with the inner (medial) side more frequently involved than the outer (lateral) side.

Leg alignment can contribute to the load distribution. In genu varum, the legs bow outwards and the knees sit further apart; in genu valgum, the knees angle towards each other. Pain is frequently noticeable when walking or bearing weight.

What is patellofemoral osteoarthritis?

This affects the joint between the femur and the patella (kneecap). According to Assurance Maladie, it accounts for approximately 35% of cases. A previous injury affecting cartilage, or certain kneecap alignment or instability problems, may contribute.

Discomfort is often noticeable during movements that load the kneecap against the femur, such as climbing stairs or bending the knee. Patellofemoral and tibiofemoral osteoarthritis may occur together; Assurance Maladie reports that combined involvement accounts for approximately 15–20% of cases.

What is bilateral gonarthrosis?

Bilateral gonarthrosis means osteoarthritis affects both knees. It does not mean that the two knees have identical changes or symptoms. One knee can be considerably more uncomfortable than the other. Both may be affected at the same time, or the second knee may develop the condition later.

Assessment and treatment therefore consider each knee and, above all, the impact on walking, everyday tasks and quality of life.

What causes gonarthrosis?

There is not always one identifiable cause. Doctors distinguish between primary osteoarthritis, where there is no obvious original injury, and secondary osteoarthritis arising in a particular context.

Age is an important factor, but osteoarthritis is not an automatic consequence of ageing. Repeated mechanical demands, frequent kneeling or squatting at work, heavy lifting and some intensive sporting activities may increase joint loading. Excess body weight also increases the forces transmitted through the knees. Researchers are investigating metabolic factors, including their associations with obesity, diabetes, high blood pressure and blood-lipid abnormalities.

Can an old knee injury increase the risk?

Yes. Osteoarthritis may develop years after a significant knee injury. Meniscal damage, an anterior cruciate ligament (ACL) tear, a fracture involving the joint or patellar instability can increase the subsequent risk. This helps explain why knee osteoarthritis sometimes appears in relatively young people with a sporting or traumatic injury history, even though it remains more common with increasing age.

Past knee or meniscal surgery does not mean osteoarthritis is inevitable, but it is useful information for a clinician assessing symptoms.

How is knee osteoarthritis diagnosed?

Diagnosis is not based on pain alone. A clinician will ask when symptoms occur, how long morning stiffness lasts, how far the person can walk and which movements cause difficulty. Examination assesses movement, possible changes in leg alignment, swelling, muscle wasting or any visible deformity.

X-rays may be used to confirm the diagnosis and identify the affected compartments. They may show narrowing of the joint space, changes to the bone beneath the cartilage or osteophytes (bony outgrowths). Imaging can help distinguish tibiofemoral from patellofemoral involvement, or show a combination of both.

Can you have knee osteoarthritis without pain?

Yes. Changes seen on an X-ray do not always match how someone feels. A person may have radiographic signs of osteoarthritis with little pain, while another may experience significant symptoms despite less dramatic imaging changes. This is sometimes called a radiographic–clinical mismatch.

Management should therefore be guided not just by a scan or X-ray but also by pain, mobility, daily activities and their effect on the person's life.

How does gonarthrosis progress?

The course differs from one person to another and is not necessarily linear. Symptoms can remain stable for a time and then flare. Some people experience slow progression with modest limitations, while others find walking, stairs, standing for long periods or getting up from a chair increasingly difficult.

It is not possible to predict any individual's future symptoms simply from their initial diagnosis.

What complications are possible?

The main impact of advanced gonarthrosis is reduced mobility and quality of life. Pain may lead people to move less; reduced activity can, in turn, contribute to muscle weakness and make everyday movement more difficult. Painful flares with swelling and stiffness may also occur.

When osteoarthritis is very advanced and substantial pain or disability persists despite appropriate care, knee replacement surgery may be discussed. Surgery is by no means an automatic outcome.

What treatments are available for knee osteoarthritis?

At present, there is no treatment that permanently cures knee osteoarthritis. Management aims to reduce pain, maintain mobility, preserve physical function and limit the impact on daily life.

Approaches are tailored to the individual. Adapted physical activity, targeted exercises and maintaining muscle strength are central. Weight loss may be recommended when excess weight increases the load on the knees. Depending on symptoms, a clinician may also recommend pain relief, physiotherapy or selected local interventions. Surgery is considered for more advanced disease causing considerable disability despite other measures.

For practical everyday steps, explore our guide to non-drug approaches and habits for knee osteoarthritis.

Should you walk if you have gonarthrosis?

Outside particularly painful flares, maintaining suitable physical activity is part of knee osteoarthritis management. Walking can remain a useful everyday activity when it is compatible with the knee's condition. Duration, intensity and terrain should be adapted to the individual.

During a painful swollen flare, activity may need to be reduced temporarily before a gradual return. Our walking and osteoarthritis guide covers this in more detail.

Which exercises are appropriate?

There is no single exercise suitable for everyone. Muscle strengthening, mobility exercises and some forms of endurance activity can all have a place, depending on the individual's abilities and joint condition. When pain significantly restricts movement, or after a long period of inactivity, advice from a doctor or physiotherapist can help tailor the programme. See also our guide to exercises for osteoarthritis.

When should you seek medical advice for knee pain?

Persistent pain deserves assessment when it increasingly limits walking, stair use or normal activities. New or marked swelling, a locked knee, pain following an injury or an unusual worsening also warrant consultation.

Not every painful knee has osteoarthritis. Although osteoarthritis is a common cause of non-traumatic knee pain after around 40–50 years of age, meniscal, tendon and ligament problems and other joint conditions may produce similar symptoms. A clinical diagnosis helps avoid incorrect assumptions.

Can gonarthrosis be cured?

Currently, no treatment can permanently cure gonarthrosis or fully restore altered cartilage to the state it was in before the disease developed. That does not mean nothing can be done: appropriate care can improve symptoms, physical abilities and the overall impact of the condition.

Are gonarthrosis and knee osteoarthritis the same thing?

Yes. “Gonarthrosis” is simply the medical term for osteoarthritis of the knee. The prefix “gon-” refers to the knee, just as “coxarthrosis” is used for hip osteoarthritis.

Can tibiofemoral and patellofemoral osteoarthritis coexist?

Yes. Both compartments can be affected in the same knee. Assurance Maladie estimates that combined involvement represents approximately 15–20% of gonarthrosis cases. The location is identified by examination and imaging when needed.

Does gonarthrosis always affect both knees?

No. It may affect only one knee, or it may be bilateral. Even when both knees have osteoarthritis, the degree of structural change and the severity of symptoms may differ on each side.

Key points to remember

Gonarthrosis is osteoarthritis of the knee and may involve the tibiofemoral compartment, the patellofemoral compartment or both. It can affect one or both knees, and the course varies considerably between people.

Pain while walking or climbing stairs, stiffness after inactivity and occasional swelling may suggest knee osteoarthritis, but symptoms alone cannot establish a diagnosis. Treatment combines individually adapted approaches; there is currently no permanent cure.

For practical measures, read about everyday approaches for knee osteoarthritis. If you are interested in the ingredients used in some joint formulas, continue with our glucosamine guide and the Laboratoire Vital Santé Joints and Mobility range.