Knee joint

The knee joint is the largest joint in the body and acts as a hinge between the thigh bone and lower leg, allowing for movement, stability and weight transfer.

Quick version

What is the knee joint?

The knee joint (articulatio genus) is a complex joint that connects the thigh bone (femur) to the shin bone (tibia) and kneecap (patella). It allows for bending and extending the leg and is essential for walking, running and jumping. The knee joint is stabilized by several ligaments, menisci and muscles that together provide freedom of movement and protection against injury.

Anatomy of the knee joint

The knee joint consists of three parts: the femorotibial joint (femur–tibia), the femoropatellar joint (femur–patella), and a network of structures that include the cruciate ligaments (ACL and PCL), collateral ligaments, menisci and joint capsule. Together they create a stable but mobile structure.

Movement and function

The knee joint mainly allows bending (flexion) and stretching (extension), but also some rotation when the leg is bent. Muscles such as the quadriceps (front of the thigh) and hamstrings (back of the thigh) control these movements and protect the joint from overload.

Protective structures

The menisci act as shock absorbers and help distribute the load in the joint. The kneecap enhances the power transmission of the thigh muscles and protects the joint in the event of a fall. The ligaments provide stability and prevent abnormal movement.

Common conditions and diseases

Pain in the knee joint can be caused by meniscus injuries, ligament tears, cartilage damage, knee osteoarthritis or inflammation. Injuries often occur during sports or sudden twisting, while osteoarthritis develops gradually with age or obesity.

Examination and diagnosis

Knee problems are investigated with a clinical examination of mobility, swelling and stability. Imaging tests such as X-rays, MRI of the knee joint or ultrasound are used to visualize internal structures and make an accurate diagnosis.

Relevant symptoms

  • Pain when walking, climbing stairs or carrying weight
  • Swelling and stiffness in the knee
  • Clicking or locking sounds when moving
  • Instability or a feeling that the knee is "giving way"
  • Limited mobility and difficulty extending the leg

Related conditions and diagnoses

  • Anterior cruciate ligament injury (ACL injury)
  • Meniscus injury
  • Knee osteoarthritis
  • Patellar luxation (dislocated kneecap)
  • Runner's knee

Questions and answers

The largest joint in the body is the knee joint, which acts as a hinge between the thigh bone and the lower leg. It enables movement such as bending and extending the leg.

Knee pain can be caused by meniscus injuries, cruciate ligament injuries, osteoarthritis, cartilage damage or inflammation. Overuse and incorrect loading are common causes.

A meniscus injury means that one of the cartilage discs in the knee joint is damaged, often when twisting or overstretching. This can cause locking and pain when straining.

To make a diagnosis, the doctor examines the knee with movement and stability tests. X-rays or MRI are used if there is suspicion of damage to the ligaments, meniscus or cartilage.

Treatment for knee injuries depends on the type of injury and may include rest, physical therapy, orthosis, or surgery for serious injuries such as cruciate ligament rupture.

It is a wear and tear of the cartilage in the knee joint that leads to stiffness, pain, and reduced mobility. It is more common with increasing age.

You should contact healthcare if you experience severe pain, swelling, instability, or if the symptoms do not go away within a few days to get help with an investigation.

Yes, tailored exercises that strengthen the muscles around the knee can reduce pain and improve function in osteoarthritis. Avoid strenuous exercises.