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What is Osteoarthritis of the Knee & What are its Causes, Signs & Symptoms

What is Osteoarthritis of the Knee?

Osteoarthritis is a degenerative joint disease caused due to wear & tear or depreciation of the joints. Osteoarthritis of the knee results from wear & tear of the knee joint and is one of the common causes of pain in the knee joint.

Osteoarthritis of the knee refers to the condition where the cartilage between joints wears away. The bones of the joints start rubbing closely and this result in swelling, pain, stiffness, bone spurs formation and decreases movement.

Osteoarthritis of the Knee

Joints are lined cartilages. This cartilage covers the bone ends and protects them from joint friction. The function of the articular cartilage is to act as a shock absorber and help in smooth movement of the joint. The joint movement is also helped by synovial fluid, which helps in lubrication and is produced by the synovial film present in the joint.

Osteoarthritis is a condition where there is degeneration of the bone cartilage. When the severity of this disease increases, the cartilage becomes weak and fragile and may even wear away completely. The bones also become thicker resulting in formation of bony “spurs.” Inflammation/swelling of the synovial film also occurs. All these factors cause a lot of pain and result in diminished movement of the knee joint. Osteoarthritis commonly occurs in load addressing joints like the hip joint or knee joint; however, it can occur in any joint.

Osteoarthritis of the knee commonly occurs in older adults who are over 50 years of age. Women are especially more prone to it. It commonly affects the inner (medial) side of the knee, although it can affect unilaterally or bilaterally to the knee joint. Athletes who are involved in physical sports like football are more prone to it. Previous bruise/wound to the knee predisposes it to osteoarthritis of the knee joint in the long run. Symptoms of osteoarthritis of the knee progress slowly over a period of years.[1]

Causes of Osteoarthritis of the Knee

Obesity/excess weight can be a cause for osteoarthritis of knee.

Below mentioned are the causes of osteoarthritis of the knee:

  • Past wounds such as ligament trauma or meniscal trauma can cause knee osteoarthritis.
  • Repetitive and extreme usage of the human knee.
  • Earlier knee fracture can also be a cause for osteoarthritis of the knee.
  • Obesity/excess weight.
  • Genetic/hereditary factors.

There are several other factors causing the osteoarthritis of the knee risk and it is commonly observed if:

  • You are a woman. Osteoarthritis of the knee is common and severe in women.
  • You are in the 40’s or a little older. This is because this is the time your muscles become weaker and the joints start rubbing as it has worn out with time.
  • Being overweight is another significant reason to develop osteoarthritis of the knee and it becomes worse.
  • You had some knee injury earlier or have undergone some knee operation such as it has led to removal of the damaged cartilage or some repairs is been done to your ligaments.
  • Your siblings or parents had or have osteoarthritis.
  • You can also develop osteoarthritis of the knee if your job is physically demanding such that repetitive activity is high; it may be some mining or farming job.
  • It may be a joint disease type that has damaged your joints and such cases are when it is a gout or rheumatoid arthritis.[2]

Signs and Symptoms of Osteoarthritis of the Knee

The following are the signs and symptoms of osteoarthritis of the knee:

  • Deep and aching pain in the inner knee can be a sign of osteoarthritis of the knee.
  • Increasing pain after physical activity.
  • Morning stiffness in the joint, which decreases with movement are the usual symptoms of osteoarthritis of the knee.
  • Swelling in the knee.
  • Clicking or cracking sounds upon knee movement maybe a sign of osteoarthritis of the knee.
  • Knee gives away as the joint structure is unstable or muscles become weak.
  • Knees become bent.
  • Knee fails to move as normal or freely.
  • Muscles enveloping the knee join become thin.

Watch Video of Knee Replacement Surgery and Arthroscopy for Osteoarthritis

Other symptoms of osteoarthritis of the knee includes, people have pain in knees to the extent that it wakes them at night. This may be unusual and happens only with people who have severe osteoarthritis. The pain varies and there may be days when you experience less or more pain, but this depends on your activeness and sometimes, even if you are active, you may be experiencing pain for no apparent reason.

Weather changes also cause knee stiffness and pain. This may be due to the knee capsules that are sensitive to atmospheric pressure changes.

Risk Factors for Osteoarthritis of the Knee

Factors increasing the risk of osteoarthritis of the knee include:

  • Gender. Women develop osteoarthritis of the knee faster to men, though the reason is unclear.
  • Occupations. In case your job demands repetitive stress on joints, it may develop knee osteoarthritis.
  • Age. Knee Osteoarthritis risk increases with age.
  • Genetics. This knee osteoarthritis is inherited and this is common.
  • Obesity. The body weight results in osteoarthritis. This adds stress on joints, such as knees and hips. The fat tissue causes harmful inflammation, as it produces proteins around your joints.
  • Joint injuries. People playing sports cause knee injuries and even due to accidents hurting the knee increases osteoarthritis risk.
  • Deformities of bone. People born with defective cartilage or malformed joints are prone to knee osteoarthritis risk.
  • Other reasons. People having rheumatic disease or diabetes also elevate the osteoarthritis risk.[4]

Complications in Osteoarthritis of the Knee

There may be atypical complications with osteoarthritis of the knee and this may include calcium crystals deposits in your cartilage and forming of cysts at the knee back.

  1. Osteoarthritis of the Knee with Crystals

    Sometimes crystals are formed during osteoarthritis of the knee and it can complicate things. The crystals are calcium chalky deposits forming in the cartilage. This is referred to as calcification and in this process the crystals are apparent in x-rays and can be understood in the joint fluid samples test done. Osteoarthritis of the knee becomes severe when crystals are formed.

  2. Baker’s Cysts and Osteoarthritis of the Knee

    Baker’s cysts formation can complicate the osteoarthritis of the knee. Baker’s cysts forms when the joint fluid is produced in extra are trapped in a pouch sticking to the joint lining. It is painless, but there may be a soft-to-firm lump at your knee back. Sometimes a cyst may ache as well.[5]

Tests to Diagnose Osteoarthritis of the Knee

  • Diagnosis can be made by the physician by assessing the nature and severity of the pain and measuring the mobility of the joint.
  • X-ray of the knee confirms the diagnosis as it shows narrowing of the joint space and bony spurs.
  • MRI scan helps in finding out if soft tissue changes have taken place within the joint.
  • Blood sample helps in distinguishing other types of arthritis.

Osteoarthritis of the knee diagnosis is done based on the signs, symptoms and examination. However, while doing examination, few other things are checked such as:

  • Muscles thinning that reduces knee support.
  • Knee tenderness.
  • Excess fluid or bony swelling.
  • Knee instability.
  • Creaking sound.
  • Restricted movement.

The most useful tests are the x-rays that help in confirming the osteoarthritis of the knee. X-rays show changes, the space narrowing between bones and joints having calcium deposits.

X-rays do not show the disability or pain levels, such as severe or minor pain. This is because it varies with each person and their ability to tolerate pain.

MRI (magnetic resonance imaging) that is a knee scan is also suggested by the doctor and this reveals the knee soft tissues, tendons, muscles and cartilage and also the bone changes that are not apparent in the regular x-rays taken. However, this is rare.

Blood test is not involved in the osteoarthritis of the knee, but is done as the last test so that it rules out any other doubtful conditions.[6]


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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:October 6, 2020

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