Definition

The knee joint consists of skeleton, cartilage, synovial membranes, menisci, ligaments and mucous sacs. Illness, injury and age-related changes can affect all of these structures. Thus, about one in four adults experience knee pain in periods. Below are many reasons listed below, most with links for more in-depth information.

Conditions that cause knee pain

Arthritis (inflammed joints)

Symptoms of arthritis include swelling, redness and heat above the knee. Also, reduced stretching veins are typical. Most ailments in the morning, unlike osteoarthritis which often worsens during activity. Eventually, weakness and instability occur due to relief and cartilage damage. Blood tests show elevated CRP and lowering reaction (SR). All age groups can be affected by arthritis.

• Childhood Arthritis (JIA)
• Borrelia infection
• Rheumatoid Arthritis (Arthritis)
• Spondyloarthritis
  • Ankylosing spondylitis
  • Psoriatic arthritis
  • Reactive arthritis
  • Arthritis of Crohn's disease or ulcerative colitis (Intestinal inflammation)
• Gout
• Calcium pyrophosphate arthritis (Pseudogic)

Osteoarthritis (osteoarthritis)

• Most often older people (> 50 years and increasing with age)
• Symptoms are stiffness and pain after exercise and little discomfort in the morning
• Late in the process, skew and unstable joints are seen
• Normal blood samples

Bakers cyst

• Popliteal swelling (behind the knee)
• May be due to arthritis or osteoarthritis of the knee joint

Shin splints

Shin splints (tendinitis along the leg bone, tibial periostitis) causes pain in the front of the legs (often both sides). Pain along the lower 2/3 of the calf at the transition to the muscles. Among the most common running injuries.

Fracture

Fracture (fracture) in the calf or femur with damage also to the joint surface can be seen after serious injury. Risk of misalignment and later osteoarthritis.

Iliotibial pain

Ilio-tibial band syndrome causes pain on the outside of the knee (laterally), especially at approx. 30 degree bend. Risk factors are training with long-distance running, cycling and weightlifting.

Knee pain

The kneecap (patella) can be painful for several reasons. The kneecap itself with underlying cartilage and joints or associated tendons can be the starting point.

• Knee fractures are rare, most often sports injuries. Acute, intense pain. Can not charge.

• Chondromalacia patella causes more diffuse pain under the patella, especially with compression. MRI shows damage to cartilage between the patella and other knee joints
• Jumpers knee caused by inflammation of the patellar tendon extending downward from the patella. Sports that include jumping and sprinting, but also being overweight are risk factors. A complication is that the tendon breaks (rupture), which causes acute pain and great difficulty walking.

• Patella luxury ("The kneecap out of joints") may be acute and recurrent, often with general hypermobility (hypermobility) which also includes Ehlers Danlos Syndrome og Marfan's syndrome

• Patello-femoral pain is among the most common causes of knee pain. May be due to congestion, but often unexplained triggering cause. Pain above and below the patella.

• Runners knee also causes patellofemoral pain (see above) and is among the most common running injuries. Not to be confused with jumpers knee which is a tendonitis.

• Tendonitis over the kneecap (see jumpers knee above)
• Sinding-Larsen's disease is inflammation of the tendon attachment at the bottom of the patella. The condition is seen among children aged 9-13 years, related to exercise. Pain during and after running, jumping and stair climbing. Reduction of physical exercise and change of exercise pattern for a period is relevant.

• Bursa inflammation at the kneecap (pre-patellar or infra-patellar bursitis). May be due to bacteria through the skin or congestion. Infection must be ruled out because antibiotic treatment is then appropriate. Gradual swelling in a few days. Typically after sitting a lot on your knees (tilers, masons). Swelling and pain just above the patella. Redness and heat, especially in case of infection. Almost normal movement in the knee.

Hoffa's syndrome

Hoffa fat pad syndrome causes pain in the front of the knee. Increased pain by sitting on knees or squatting, walking or running.

Knee infection

Infection in the knee joint (Septic arthritis) is always serious and is most often caused by bacteria. Painful, red, hot (may look like gout or reactive arthritis). Some people get a fever.

• Gonococcal infection is often irritable and can attack the knee.
• Borrelia infection also causes swelling and increased heat over the joint.

Cancer with knee pain

Cancer is rarely the cause, however tumor in the skeleton can cause knee pain.

Loose cartilage

Loose cartilage or bone in the knee joint (Osteochondritis) is due to the fact that parts of cartilage and bone substance can detach from the joint surfaces. Pain during and after sports and a tendency to swelling in the knee are common. Prior injury is unusual. The condition is also seen by child joints (JIA). X-ray CT or MRI examinations are relevant. X-ray CT or MRI examinations are relevant. Surgical treatment may be necessary in approx. 50%.

Menisci and knee pain

Meniscus injuries

• Damage to menisci can occur due to acute injury or wear (degenerative meniscus injury). Because the menisci protect the knee joint from osteoarthritis, surgical removal of the menisci is unfavorable.

• Acute meniscus injury is most often seen among younger active people and in major injuries where the cruciate ligament can also be injured. Both the lateral meniscus (on the outside of the knee) and the medial meniscus (inside) can be damaged. In the event of acute injury, meniscus-preserving surgery with repair is attempted as far as possible. In the case of degenerative medical injury, non-surgical treatment is usually attempted for at least three months before any intervention. 

• Meniscal wear (degenerative lateral meniscus rupture). The condition can develop gradually (over years) among middle-aged and elderly people without prior injury or by twisting, squatting or running. The injury can be painful or accidentally detected by MRI or arthroscopy (peephole surgery) for another reason. Pain on the outside of the knee (lateral), slipping, pain on compression and / or swelling in the knee. The knee can "lock" (reference: Kise NJ, 2022).

Osteochondritis: See Loose cartilage or bone above

Osteonecrosis of the knee

Osteonecrosis, Avascular necrosis due to failure of blood circulation to the bone tissue. Causes can be injury (knee out of joint) or high doses of cortisone (Prednisone). Some diseases such as Systemic lupus (SLE) og Gaucher's disease also disposes.

Pes hellerinus

Pes anserinus bursitis (mucositis) causes pain and swelling on the inside just above the knee, especially when getting up from a chair or going up stairs. Osteoarthritis disposes.

Plica syndrome

Plica syndrome. The condition is seen when running. Pain on the inside of the patella when stretching and bending.

Poplite inflammation

Popliteus tendonitis gives pain behind the knee. Sports injury, especially when running down hills.

Accident

• Side Ligaments
• Front crossband
• Meniscus (lateral og medial meniscus)
• The kneecap (patella) is luxated ("dislocated")
• Patellar tendon
• Fracture of the joint

Schlatter (Tibial tuberculosis apophysitis)

• Teenagers
• Pain under knee, especially after stress

Mucositis (bursitis): See «kneecap» and «pes hellerinus» above

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