The knee is a hinge joint that connects the femur (thighbone), tibia (shinbone), and patella (kneecap). The knee’s structure allows for bending, straightening, and slight rotational movements, enabling essential functions like walking, running, and jumping.

Articular cartilage is the smooth, white tissue covering the ends of the bones inside the joint. When the knee is damaged, it can lead to knee cartilage defects that impair joint function and cause significant discomfort.

Knee articular cartilage provides a frictionless surface, allowing bones to glide against each other effortlessly. It also cushions the bones and absorbs impacts which reduces stress on the joint.  Articular cartilage also helps distribute weight evenly across the knee, preventing excessive pressure on any single point.

A knee cartilage defect refers to a localized area of damaged or deteriorated cartilage within the joint. Unlike other soft tissues, cartilage cannot regrow. Small defects can progress into larger lesions over time. Left untreated, cartilage defects allow the bones to rub together causing pain and dysfunction, and leading to progressive joint deterioration, increasing the likelihood osteoarthritis. The most common condition that results in a knee replacement surgery is osteoarthritis.

Cartilage defects can develop due to various factors, including:

• Trauma or Injury: Direct impact to the knee from a fall, sports injury, or accident can damage the cartilage.
• Repetitive Stress and Overuse: High-impact sports such as football, basketball, and soccer increase the risk of cartilage injuries due to repetitive stress and sudden changes in direction. Athletes and individuals with physically demanding jobs may develop cartilage damage over time due to repeated knee strain. Running, jumping, and squatting can gradually wear down the cartilage.
• Degenerative Conditions: Age-related wear and tear can lead to cartilage deterioration. Osteoarthritis, a degenerative joint disease, is a common cause of cartilage thinning and defects.
• Poor Knee Alignment: Abnormal biomechanics or knee misalignment can place uneven pressure on the joint, leading to cartilage wear in specific areas.
• Obesity: Excess body weight places additional stress on the knee joint, accelerating cartilage breakdown and increasing the risk of defects.

Knee cartilage defects may present with various symptoms, depending on the severity and location of the damage. Common symptoms include:

• Pain: Often localized to the affected area, pain may worsen with activity and improve with rest.
• Swelling and inflammation: The knee may become swollen due to irritation of the joint lining.
• Stiffness: Limited range of motion and difficulty fully straightening or bending the knee.
• Clicking or grinding sensation: Some individuals may feel or hear a clicking, grinding, or catching sensation when moving the knee.
• Instability: A feeling of the knee “giving out” or being unable to support weight properly.
• Locking of the knee: In severe cases, loose cartilage fragments may cause the knee to lock in place temporarily.

These symptoms can progressively worsen if the defect is not addressed, negatively impacting daily activities and reducing mobility.