Gonarthrosis (knee osteoarthritis)

Knee osteoarthritis is the progressive wear (arthrosis) of the knee joint. Such wear can be due to a predisposition or may be the result of an illness or accident. Older people in particular are affected.

Knee osteoarthritis takes two different forms: primary (due to predisposition) and secondary (acquired) osteoarthritis. This primary knee osteoarthritis frequently occurs in more advanced adult age, so that about 75% of all people older than 50 years and around 90% of the over 70-year-olds suffer from corresponding joint changes. 

Secondary osteoarthritis can be the result of an accident, for example in the case of a direct injury to the cartilage. Other causes include inflammation or also an internal illness such as rheumatism. 

Many individuals are able to live with the diagnosis so that the ongoing treatment of joint wear is not required. The quality of life is impaired in about 20% of the affected individuals.

Anterior cruciate ligament injury (ACL)

An ACL injury is a tear or sprain of the anterior cruciate (KROO-she-ate) ligament (ACL) — one of the major ligaments in your knee. ACL injuries most commonly occur during sports that involve sudden stops or changes in direction, jumping and landing — such as soccer, basketball, football and downhill skiing. Many people hear or feel a "pop" in the knee when an ACL injury occurs. Your knee may swell, feel unstable and become too painful to bear weight.

Posterior cruciate ligament injury (PCL)

Posterior cruciate ligament (PCL) injury happens far less often than does injury to the knee's more vulnerable counterpart, the anterior cruciate ligament (ACL). The posterior cruciate ligament and ACL connect your thighbone (femur) to your shinbone (tibia). If either ligament is torn, it might cause pain, swelling and a feeling of instability.

Meniscus injury

A meniscus injury occurs because of trauma caused by forceful twisting or hyper-flexing of the knee joint. Symptoms of a injured or torn meniscus include knee pain, swelling, popping, and giving way. Treatment may include observation and physical therapy with muscle strengthening to stabilize the knee joint.

Knee ligament sprains

Knee ligament sprains or tears are a common sports injury.  Your knee ligaments connect your thighbone to your lower leg bones. The medial collateral ligament (MCL) and lateral collateral ligament (LCL) are found on the sides of your knee.

Athletes who participate in direct contact sports like football or soccer are more likely to injure their collateral ligaments. Symptoms include pain at the sides of your knee. If there is an MCL injury, the pain is on the inside of the knee; an LCL injury may cause pain on the outside of the knee. The location of the injury may swell, and the knee may feel instable, the feeling that your knee is giving way.

Patellofemoral pain syndrome (PFPS) 

Patellofemoral pain syndrome (PFPS) is a broad term used to describe pain in the front of the knee and around the patella, or kneecap. It is common in people who participate in sports—particularly females and young adults—but PFPS can occur in nonathletes, as well. The pain and stiffness caused by PFPS can make it difficult to climb stairs, kneel down, and perform other everyday activities.