what causes a piece of cartilsge to be missing

The most common cause of knee pain is knee arthritis. The pain may come and go, become worse over time, and be accompanied by other symptoms, such as genu stiffness.

Knee osteoarthritis is a condition where cartilage in the knee degenerates, or breaks downwardly.
Watch: Knee Osteoarthritis Video

Genu osteoarthritis is divers past degeneration of the knee'southward articular cartilage—the flexible, slippery material that normally protects bones from joint friction and impact. The condition too involves changes to the bone underneath the cartilage and can affect nearby soft tissues.

See What Is Osteoarthritis?

Other types of knee arthritis
Knee joint osteoarthritis is by far the almost common type of arthritis to cause knee pain, and ofttimes referred to as simply human knee arthritis. Many other less common types of arthritis tin can also crusade human knee pain, including rheumatoid arthritis, pseudogout, and reactive arthritis.

See 6 Types of Arthritis that Affect the Knee

advertisement

The Damage and Loss of Genu Cartilage

The defining feature of osteoarthritis is the breakup and loss of articular cartilage. In the knee, articular cartilage covers the top of the tibia (shinbone), the lesser of the femur (thigh os) and the back of the patella (kneecap). Articular cartilage protects the surfaces of these bones where they meet at the joint. During the evolution of osteoarthritis:

• Cartilage weakens. The composition of the articular cartilage changes, condign weaker. This change in composition is peculiarly common in older historic period.
• Cartilage becomes damaged. The weakened articular cartilage thins or wears away.
• Cartilage may try to heal. The damaged cartilage may attempt to produce new cells, but information technology is not enough to replace the missing cartilage. In addition, these new cells may abound in irregular, bumpy patterns rather than the smooth pattern of the original cartilage.
• Meniscus impairment is likely. Impairment to the knee's meniscus is likely to also occur.¹ Because meniscal cartilage is different from articular cartilage, meniscus damage is considered a dissever just related condition to knee osteoarthritis.

See What Is Cartilage?

Cartilage does not contain nerves, so damaged cartilage does non necessarily cause hurting. Instead, the damaged or missing knee cartilage causes other problems, such as friction between bones and changes to bone tissue, which tin can crusade pain.

In This Article:

Changes to the Knee Joint'due south Bones

Lateral view of the basic in the articulatio genus joint. Due to osteoarthritis, the cartilage has degenerated and bony growths have developed.

Infographic:
Osteoarthritis
(larger view)

When cartilage is damaged, bones experience more friction and impact. This can crusade the os to undergo changes. For example:

• Os spurs. Abnormal bony growths, called osteophytes or bone spurs, develop on the os at the knee joint joint. It is believed that bones produce os spurs to recoup for deteriorated or missing cartilage by redistributing weight loads. The bone spurs can create more friction in the knee joint, leading to discomfort and pain. It is of import to annotation that bone spurs are a normal sign of aging, and the presence of them alone is non a cause for concern.
• Subchondral bone sclerosis. The surfaces of the tibia and femur that lie but beneath genu cartilage can change in composition and harden. ("Chondral" means cartilage; subchondral bone is located but beneath cartilage. "Sclerosis" means hardening.)
• Cysts and bone marrow lesions. The os underneath damaged or missing human knee cartilage may develop cysts (typically referred to as "subchondral cysts") and areas of abnormal swelling called bone marrow lesions. These lesions may exist associated with human knee pain.^{two - three}

Subchondral os sclerosis and os marrow lesions can occur at whatever time but are specially common in the afterward stages of articulatio genus arthritis.

advertisement

Changes to the Knee joint Articulation's Fluid

The knee joint contains fluid, chosen synovial fluid. Typically, this fluid promotes good for you cartilage and lubricates the articulation. In an arthritic knee joint, both the composition and the amount of joint fluid in the articulatio genus joint can change.⁴

Meet What Is a Synovial Articulation?

Changes to the Knee Joint's Soft Tissues

As the body attempts to compensate for arthritic changes in the genu joint, the surrounding soft tissues undergo stress. For example, the nearby tendons and ligaments may become strained and/or the meniscus may become injured, leading to further loss of stability and function in the knee joint.

See Knee Anatomy

References

• 1.Englund M, Guermazi A, Lohmander LS. The meniscus in genu osteoarthritis. Rheum Dis Clin North Am. 2009 Aug;35(3):579-xc. doi: 10.1016/j.rdc.2009.08.004. Review. PubMed PMID: 19931804.
• ii.Felson DT, Chaisson CE, Hill CL, Totterman SM, Gale ME, Skinner KM, Kazis L, Gale DR. The association of os marrow lesions with pain in knee osteoarthritis. Ann Intern Med. 2001 Apr 3;134(7):541-nine. PubMed PMID: 11281736.
• 3.Collins JA, Beutel BG, Strauss E, Youm T, Jazrawi L. Os Marrow Edema: Chronic Bone Marrow Lesions of the Knee joint and the Association with Osteoarthritis. Bull Hosp Jt Dis (2013). 2016 Mar;74(1):24-36. Review. PubMed PMID: 26977546.
• 4.Roemer FW, Guermazi A, Felson DT, et al. Presence of MRI-detected joint effusion and synovitis increases the take a chance of cartilage loss in knees without osteoarthritis at 30-month follow-up: the Nigh study. Ann Rheum Dis. 2011;lxx(10):1804-ix.

marcouxsaling.blogspot.com

Source: https://www.arthritis-health.com/types/osteoarthritis/what-knee-osteoarthritis