Why can I bend my knees backwards

Knee problems

Causes: what are the causes of knee problems?

Knee problems are very common because the knee joint is heavily stressed in everyday life and during sports. The structures of the knee - bones, cartilage, menisci, cruciate ligaments, collateral ligaments or the kneecap - can be injured, improperly or overstrained, worn out or inflamed. Knee pain is the result.

There are many causes of knee problems. This includes:

  • Congenital disorders such as knock knees or bow legs
  • Growing pains in young adults
  • Inflammation of the knee due to an infection (knee empyema)
  • Non-bacterial inflammation (primarily rheumatoid arthritis)
  • Arthrosis (joint wear) in the knee (gonarthrosis)
  • Bursitis (prepatellar bursitis)
  • Meniscus damage
  • Ligament injuries to the knee joint (such as the cruciate ligament tear)

Complaints: How do knee problems express themselves?

Knee problems manifest themselves differently depending on the cause. The symptoms can appear alone or in combination.


The knee cannot be bent or straightened, and there is sometimes pain and swelling. A blockage is usually caused by a meniscus damage or a free joint body.

Stretch inhibitions

If the extension inhibition suddenly occurs, the knee cannot be fully extended. Usually a meniscus damage or a free joint body trigger this complaint. If an inhibition of extension occurs - often in connection with an inhibition of flexion - gradually over years, the cause is often osteoarthritis (joint wear) in the knee. The restriction of movement in the knee can be accompanied by pain, swelling, redness and a feeling of warmth.


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Buckling while walking

The affected person no longer has muscular knee control. If you don't concentrate fully on walking, your knee will buckle. Such instability of the knee can be triggered by an anterior cruciate ligament tear or, less commonly, by cartilage damage or osteoarthritis (joint wear). In addition, there may be pain, swelling or noises in the knee.

Noises in the knee

A "cracking" knee when bending often occurs without any further discomfort. In young people, the cause can be meniscus damage, cartilage damage, a pinched crease in the mucous membrane, or a dislocated kneecap. In older people, osteoarthritis (joint wear) usually causes cracking or cracking noises in the knee.


A reddened knee is often a sign of inflammatory disease. If parts of the knee or the entire knee are brightly red, the disease is in its early stages. The darker the redness, the more the knee inflammation progresses. It usually manifests itself in knee pain, overheating, swelling, restricted mobility and possibly a general feeling of illness and fever.


Stress pain in the knee is usually caused by mechanical damage (e.g. meniscus damage). If the knee only hurts when going downhill or down stairs, this indicates problems with the kneecap. Pain at rest is usually a sign of an inflammatory disease of the knee.


The knee swells, the kneecap can be moved very easily with relaxed muscles and pushed into the depths of the knee. Swelling can be accompanied by redness, overheating, restricted mobility and pain. Knee swelling can be caused by meniscus damage, cartilage damage, ligament instability, or an inflammatory disease.


A more or less hot knee can be caused by an inflammation in the knee, an irritation in the case of osteoarthritis (joint wear) or a previous operation.

Diagnosis: How are knee problems diagnosed?

It is advisable to have permanent and acute knee problems examined by a doctor (family doctor, orthopedist or trauma surgeon). He first asks about the exact complaints and the medical history (anamnesis). This is followed by some tactile and movement examinations. As a rule, the doctor also examines the healthy leg for comparison. If the symptoms allow, the doctor also looks at how the person concerned is doing.

Further examinations for knee problems are an X-ray examination, ultrasound examination (sonography), knee-joint examination (arthroscopy), knee-joint puncture and magnetic resonance tomography (MRT). Laboratory tests of blood and urine can also be useful in diagnosing knee problems, for example to detect inflammation.

Treatment: How can knee problems be treated?

Knee problems can be treated conservatively, i.e. without surgery, or surgically. In the conservative therapy Ointments, gels, creams, lotions and cooling compresses with ice are often used. Active ingredients that are applied to the knee can have a cooling or warming effect. Usually anti-inflammatory or anti-rheumatic drugs are also added. Acute inflammations or injuries as a result of accidents are treated with cold and immobilized.

Bandages, tape bandages and support stockings are further measures in the conservative treatment of knee problems. They support the stability of the knee and stimulate tension in the muscles through pressure. This prevents abnormal movements and knee pain. Plastic splints with built-in side joints (orthoses) are used after accidents or operations. These only allow certain movements and loads on the knee.

Other conservative treatment options for knee problems include:

  • Treatment with electricity
  • Ultrasound treatment
  • Treatment with electromagnetic waves
  • Light and laser therapy
  • Massages and lymph drainage
  • acupuncture
  • Treatment with pain reliever drugs
  • Joint injections, infiltration and neural therapy (narcotics and / or medication are injected directly into the knee)

If the doctor cannot adequately alleviate the knee problems through conservative treatment or if it is an injury as a result of an accident operational measures into consideration. Surgery on the knee is performed either under general anesthesia or with spinal anesthesia. Many measures, such as the removal of cartilage or the treatment of meniscus damage, are carried out by means of an arthroscopy. The doctor rarely operates on the open knee: For example, in the case of displaced fractures of the joint surfaces, cartilage-bone transplants and the implantation of artificial sliding surfaces.

Prognosis: What is the prognosis for knee problems?

The prognosis of knee problems depends on the underlying cause, age, and mobility of the person affected. Treatment is often lengthy. Operations on the knee, in particular, often require intensive follow-up treatment with orthoses. If you have chronic knee problems, it is usually advisable to move your knee. However, loads and overloads are not recommended.

Prevention: How can you prevent knee problems?

Not all knee problems can be prevented. Exercising caution can protect against knee injuries. Early treatment is advisable for symptoms that arise as a result of joint wear and tear or previous illnesses. In the case of recurring knee problems, it is advisable to avoid irritation.

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additional Information

additional Information

Author: Theresa Nikley, Dr. med. M. Waitz
Date of llast update: October 2017
Baumgartner, R. et al .: Checklist Orthopedics. Thieme, Stuttgart 2014
Elsen A. et al .: Orthopedics and trauma surgery for study and practice. Medical publishing and information services, Breisach 2016/17
Krämer, J .: Orthopedics, trauma surgery. Springer, Berlin 2013
Largiader, F .: Surgery checklist. Thieme, Stuttgart 2012