Knee pain is a common problem that can affect people of all ages. It may occur when walking, bending the knee, exercising or even resting, and its causes can vary considerably.
Some of the most common factors associated with knee pain include:
- Excess body weight, which increases the load placed on the knee joints.
- Changes in walking patterns, foot alignment or biomechanics.
- Joint conditions such as osteoarthritis.
- Sports injuries, accidents or repetitive strain.
- Congenital or structural abnormalities affecting the knee.
The location of knee pain can provide useful clues about its possible cause. However, identifying the underlying condition requires a medical assessment, which may include a physical examination and, when appropriate, imaging tests such as X-rays or magnetic resonance imaging (MRI).
Understanding where the pain occurs and which movements trigger it can help guide diagnosis and treatment.
In this article, we explain the different types of knee pain, their possible causes and the treatments available to help relieve discomfort and improve joint function.
Pain behind the knee: possible causes
Pain behind the knee, also known as posterior knee pain, can be associated with several structures, including tendons, muscles, ligaments and the joint capsule.
Some of the possible causes include:
- Hamstring tendinopathy: Irritation or injury affecting the hamstring tendons may cause discomfort behind the knee, particularly during movement or physical activity.
- Baker’s cyst: A fluid-filled swelling that develops behind the knee, often associated with an underlying joint condition such as osteoarthritis or a meniscal injury. It may cause tightness, swelling or discomfort when bending or straightening the leg.
- Meniscal injuries: Damage to the posterior part of the medial or lateral meniscus can sometimes cause pain behind the knee, although symptoms may also be felt along the inner or outer side of the joint.
Although many causes are musculoskeletal, sudden swelling or pain behind the knee, particularly when accompanied by calf swelling, warmth or redness, requires prompt medical assessment to rule out conditions such as deep vein thrombosis.
Pain on the inner side of the knee
Pain on the inner side of the knee is known as medial knee pain.
It is relatively common and may develop gradually through repetitive strain or occur suddenly following an injury.
Possible causes include:
- Medial meniscus injury: The medial meniscus is a cartilage structure that helps distribute pressure within the knee joint. Degenerative changes or traumatic tears can cause pain, stiffness and sometimes catching or locking sensations.
- Medial collateral ligament injury: This ligament helps stabilise the inner side of the knee. Sprains may occur when the joint is subjected to excessive sideways force.
- Pes anserine bursitis: Inflammation of a small fluid-filled sac near the inner side of the upper tibia can cause pain below the knee joint, particularly during walking, climbing stairs or physical activity.
Identifying the exact location of the discomfort and assessing the movements that trigger it can help distinguish between these conditions.
Pain on the outer side of the knee
Pain affecting the outer side of the knee is known as lateral knee pain.
Although it can be associated with a lateral meniscus injury, there are several other possible causes.
These include:
- Lateral meniscus injury: Damage to the cartilage on the outer side of the knee, sometimes associated with twisting movements or sports injuries.
- Lateral collateral ligament injury: A sprain or tear affecting the ligament that stabilises the outer part of the knee.
- Iliotibial band syndrome: A condition frequently associated with repetitive activities such as running or cycling, causing pain along the outer side of the knee.
- Osteoarthritis: Degenerative changes affecting the outer compartment of the knee joint.
The most appropriate treatment depends on the underlying cause, the severity of the symptoms and the patient’s activity level.
Knee pain when walking
Knee pain when walking is a common symptom and may be associated with several conditions, particularly osteoarthritis.
Knee osteoarthritis occurs when changes develop in the joint cartilage and surrounding tissues, leading to pain, stiffness and reduced mobility.
It becomes more common with age, although it can also affect younger individuals, particularly those with previous joint injuries or other risk factors.
Typical symptoms include:
- Pain during walking or weight-bearing activities.
- Stiffness after periods of inactivity.
- Difficulty climbing or descending stairs.
- Swelling or reduced knee mobility.
- Discomfort that may improve with rest, particularly in earlier stages.
In more advanced cases, pain may also occur at rest or during the night.
However, pain while sitting or lying down does not necessarily indicate severe osteoarthritis or mean that knee replacement surgery is required.
Treatment decisions depend on clinical findings, imaging results, symptom severity and the impact on daily life.
Knee pain when bending the knee
Pain when bending or flexing the knee can occur for several reasons.
Two possible causes are:
- Meniscal injuries: Damage to the meniscus can cause discomfort during deep knee bending, squatting or twisting movements. Some patients also experience clicking, catching or locking sensations.
- Patellofemoral pain: Pain arising from the joint between the kneecap (patella) and the thigh bone (femur). It may be associated with altered kneecap tracking, muscle weakness, repetitive loading or structural factors.
Patellofemoral pain often becomes more noticeable when climbing stairs, squatting, running or sitting with the knees bent for prolonged periods.
In some cases, structural variations such as a high-riding kneecap or patellar malalignment may contribute to increased joint stress.
Over time, certain joint conditions can be associated with cartilage changes, although not everyone with patellofemoral pain will develop osteoarthritis.
Knee pain at rest or during the night
Knee pain does not always occur during movement. Some people experience discomfort while sitting, lying down or sleeping.
Possible causes include:
- Osteoarthritis: Joint pain may persist at rest in some patients, particularly when the condition is more advanced.
- Inflammatory joint conditions: Arthritis and other inflammatory disorders can cause persistent pain, swelling and stiffness.
- Recent injuries: Pain following physical activity or an injury may continue temporarily after movement has stopped.
- Tendon or soft tissue irritation: Certain positions may place pressure on sensitive structures around the knee.
Persistent or worsening knee pain at rest should be assessed by a healthcare professional, especially when accompanied by significant swelling, fever, redness or an inability to bear weight.
Knee ligament pain: symptoms and causes
The knee contains four main ligaments that contribute to joint stability:
- Lateral collateral ligament (LCL): Located on the outer side of the knee.
- Medial collateral ligament (MCL): Located on the inner side of the knee.
- Anterior cruciate ligament (ACL): Helps control forward movement and rotation of the tibia.
- Posterior cruciate ligament (PCL): Helps prevent excessive backward movement of the tibia.
Ligament injuries may occur during sports, falls, sudden changes of direction or direct impacts.
Symptoms vary depending on the affected ligament and the severity of the injury.
For example, an anterior cruciate ligament injury may cause a popping sensation, swelling and a feeling that the knee is unstable or giving way.
Collateral ligament injuries may produce more localised pain along the inner or outer side of the knee.
Patellar tendinopathy or jumper’s knee
Another possible cause of pain at the front of the knee is patellar tendinopathy, commonly known as jumper’s knee.
This condition affects the patellar tendon, which connects the kneecap to the shinbone.
It is particularly common in sports involving repeated jumping, running or rapid changes of direction.
Symptoms typically include pain just below the kneecap, especially during activities that place increased load on the tendon.
Osgood-Schlatter disease
Osgood-Schlatter disease is another condition that can cause pain at the front of the knee, particularly in physically active children and adolescents.
It affects the area where the patellar tendon attaches to the upper part of the tibia.
During periods of growth, repeated tension on this area can cause pain, tenderness and a noticeable bump below the kneecap.
Symptoms often improve as skeletal growth finishes, although appropriate activity management may be needed.
How is knee pain diagnosed?
Because knee pain can have many different causes, an accurate diagnosis is essential for selecting the most appropriate treatment.
At Clínica Planas, the assessment may involve several stages.
- Medical history and physical examination: The specialist assesses the location and characteristics of the pain, previous injuries, physical activity, mobility and joint stability. Walking patterns and posture may also be evaluated.
- Additional medical tests: Blood tests may be requested when an inflammatory, infectious or systemic condition is suspected. They are not routinely necessary for every type of knee pain.
- Diagnostic imaging: X-rays, ultrasound or MRI scans may be recommended depending on the suspected cause and the clinical findings.
Based on the results, the medical team can develop a personalised treatment plan adapted to the patient’s condition and needs.
Treatments for knee pain
The most effective treatment for knee pain depends on its underlying cause, severity and impact on mobility and daily activities.
Not all knee conditions require surgery, and many can be managed through conservative treatments.
Physiotherapy and rehabilitation
Physiotherapy is often an important part of managing knee pain.
Depending on the diagnosis, treatment may include:
- Strengthening exercises for the muscles supporting the knee.
- Mobility and flexibility exercises.
- Balance and stability training.
- Gradual return-to-activity programmes.
- Advice on movement patterns and load management.
A personalised rehabilitation programme can help improve joint function, reduce discomfort and support long-term mobility.
Medical and injectable treatments
Depending on the condition, specialists may consider medication or injectable treatments to manage symptoms.
For example, hyaluronic acid injections are sometimes used for knee osteoarthritis, although their effectiveness varies and they are not routinely recommended by all clinical guidelines.
Other options may be appropriate in selected circumstances following an individual medical assessment.
Regenerative and complementary therapies
At Clínica Planas, the medical team may also assess whether certain regenerative or complementary approaches are suitable for individual patients.
These may include:
- Hyperbaric oxygen therapy.
- Regenerative medicine treatments.
- Cytokine-based approaches.
- Monocyte-based treatments.
- Ozone therapy.
It is important to note that the evidence supporting these approaches for common causes of knee pain remains limited or inconsistent. They should not be considered established replacements for evidence-based treatments such as exercise therapy, appropriate medication or surgery when indicated.
The potential benefits, risks and limitations of any proposed treatment should be discussed with a qualified specialist.
When is knee surgery necessary?
Surgery may be considered for certain ligament injuries, mechanical problems or advanced joint conditions when appropriate non-surgical treatments have not provided sufficient relief.
In cases of severe knee osteoarthritis, knee replacement surgery may be an option when pain and functional limitations significantly affect quality of life.
However, the decision to undergo surgery should always be based on a comprehensive clinical assessment rather than symptoms alone.
When should you see a specialist for knee pain?
Although mild knee discomfort may improve with rest and appropriate activity modification, some symptoms require medical attention.
You should seek assessment if:
- Knee pain persists or becomes progressively worse.
- You experience repeated swelling or stiffness.
- The knee feels unstable or gives way.
- You cannot fully bend or straighten the joint.
- Pain interferes with walking, sleeping or everyday activities.
Seek urgent medical attention if you cannot bear weight following an injury, the knee appears significantly deformed, or you experience a hot, swollen joint accompanied by fever.
Sudden calf swelling or pain may also require urgent assessment.
Personalised knee pain assessment at Clínica Planas
Understanding the cause of knee pain is the first step towards finding an effective treatment.
At Clínica Planas, our specialists assess each patient’s symptoms, medical history and physical condition to identify the factors contributing to discomfort.
Through a personalised approach, the aim is to relieve pain, improve joint function and help patients maintain their mobility and quality of life over time.
If you experience persistent knee pain, a specialist assessment can help determine the most appropriate next steps for your individual situation.
RECOMMENDED TREATMENTS
Localised pain treatment
Relieving persistent muscle pain and discomfort can make a significant difference to your quality of life.
Ozone therapy
Medical ozone therapy is used as a complementary treatment for certain conditions, with the aim of relieving symptoms and supporting recovery. However, evidence of its effectiveness remains limited.
Hair transplant
Hair transplant surgery involves implanting hair follicles into areas affected by hair loss, encouraging new hair growth and providing natural-looking, long-lasting results.
