Arthritis is a general term covering numerous conditions where the joint surface or cartilage wears out. The joint surface is covered by a smooth articular surface that allows pain-free movement in the joint. This surface can wear out for several reasons; often the definite cause is not known. Arthritis often affects the knee joint.

When the articular cartilage wears out, the bone ends rub on one another and cause pain. This condition is referred to as Osteoarthritis or “wear and tear” arthritis, as it occurs with aging and use. It is the most common type of arthritis.

The anterior cruciate ligament, or ACL, is one of the major ligaments of the knee that is in the middle of the knee and runs from the femur (thighbone) to the tibia (shinbone). It prevents the tibia from sliding out in front of the femur. Together with posterior cruciate ligament (PCL) it provides rotational stability to the knee.

An ACL injury is a sports-related injury that occurs when the knee is forcefully twisted or hyperextended. An ACL tear usually occurs with an abrupt directional change with the foot fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, and direct contact or collision, such as a football tackle can also cause injury to the ACL.

An ACL injury is a sports-related injury that occurs when the knee is forcefully twisted or hyperextended. An ACL tear usually occurs with an abrupt directional change with the foot fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, and direct contact or collision, such as a football tackle can also cause injury to the ACL.

Meniscus tear is the commonest knee injury in athletes, especially those involved in contact sports. A sudden bend or twist in your knee causes the meniscus to tear. This is a traumatic meniscus tear. Elderly people are more prone to degenerative meniscal tears as the cartilage wears out and weakens with age. The two wedge-shaped cartilage pieces present between the thighbone and the shinbone are called meniscus. They stabilize the knee joint and act as “shock absorbers”.

Torn meniscus causes pain, swelling, stiffness, catching or locking sensation in your knee making you unable to move your knee through its complete range of motion.

The knee, mostly the femoral condyles are most commonly affected. The two femoral condyles make up for the rounded end of femur (thighbone). Each knee has two femoral condyles, the medial femoral condyle on the inside of the knee and the lateral femoral condyle on the outside of the knee. Osteochondritis dissecans occurs within the lateral aspect of the medial femoral condyle. The condition can also occur in other joints, including your elbows, ankles, shoulders and hips .Osteochondritis dissecans is a joint condition in which a piece of cartilage, along with a thin layer of the bone separates from the end of the bone because of inadequate blood supply. The separated fragments are sometimes called “joint mice”. These fragments may be localized, or may detach and fall into the joint space causing pain and joint instability.

Osteochondritis dissecans is more common among boys and young men between 10 and 20 years who actively take part in sports. Athletes participating in sports such as gymnastics and baseball may develop osteochondritis dissecans

Patellar tendinitis, also known as “Jumper’s knee" is an inflammation of the patellar tendon that connects your kneecap (patella) to your shinbone. This tendon helps in extension of the lower leg.

Patellar tendinitis usually results from repetitive trauma or overuse, particularly from sports activities involving jumping such as basketball or volleyball. Therefore, this condition is known as jumper’s knee. Rarely, this condition may also occur because of an acute injury to the tendon that has not healed properly.

Overusing knees can result in various injuries, such as patellar tendinitis, patellofemoral pain syndrome, cartilage breakdown, and ligament strains, including ACL tears. These conditions can lead to pain, inflammation, and reduced mobility, emphasizing the importance of proper form, rest, and gradual intensity increase to prevent knee-related issues.

Articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. Cartilage helps the bones move smoothly against each other and can withstand the weight of the body during activities such as running and jumping. Articular cartilage does not have a direct blood supply to it, so has less capacity to repair itself. Once the cartilage is torn it will not heal easily and can lead to degeneration of the articular surface, leading to development of osteoarthritis.

The damage in articular cartilage can affect people of all ages. It can be damaged by trauma such as accidents, mechanical injury such as a fall, or from degenerative joint disease (osteoarthritis) occurring in older people.

Patellar (kneecap) instability results from one or more dislocations or partial dislocations (subluxations). Patella is the small piece of bone in front of the knee that slides up and down the femoral groove (groove in the femur bone) during bending and stretching movements. The ligaments on the inner and outer sides of the patella hold it in the femoral groove and avoid dislocation of the patella from the groove. Any damage to these ligaments may cause the patella to slip out of the groove either partially (subluxation) or completely (dislocation). This misalignment can damage the underlying soft structures such as muscles and ligaments that hold the kneecap in place. Once damaged, these soft structures are unable to keep the patella (kneecap) in position. Repeated subluxation or dislocation makes the knee unstable and the condition is called as knee instability.