Pain in the knee joint is very common and occurs in people of all ages. The knee joint provides hinge-like movement to the leg and supports the weight of the body during standing and movement. The knee joint is composed of various components, including bones, cartilage, ligaments, tendons and muscles. Each of these structures is susceptible to injury, damage, joint inflammation and wear and tear, causing joint pain and weakness.
Ligament Injury
The four main ligaments of the knee joint--the anterior cruciate, posterior cruciate, lateral collateral and the medial collateral--help to stabilize the joint and bind it together. According to the National Institute of Arthritis, Musculoskeletal and Skin Diseases, ligament injuries, sprains or tears and ruptures are common causes of pain and swelling inside the knee. Damage to the knee ligaments can occur due to injuries, accidents, inflammation, overuse, age-related wear or weakened supporting muscles around the knee. Anterior cruciate, or ACL, injuries are the most common sports-related ligament injuries; they generally occur if the knee is suddenly jerked or twisted while the foot remains stationary.
Bone and Cartilage Damage
The long bones of the upper leg meet the bones of the lower leg at the knee joint. The four bones that make up the joint are the femur, or thigh bone, the tibia and fibula bones in the lower leg and the patella, or knee cap. As described at LightSpeedPhysio.com, degenerative diseases such as rheumatoid arthritis, osteoarthritis and osteoporosis, or loss of bone density, can cause inflammation or weakness in the joints due to damage to the bone and cartilage. The bones of the knee joint, particularly the patella, may also be inflamed or slightly or completely dislocated due to a fall, vehicle accident, sports injury or simply wear and tear.
Muscle and Tendon Pain
The muscles above, below and wrapped around the knee joint are very important in providing strength and stability to the knee. The two groups of muscles that do this are the quadriceps, or thigh, muscles and the hamstring muscles that run from the hip, along back of the thigh to below the knee. These muscles power the movement of the knee joint, allowing it to bend and extend. The tendons anchor the muscles to the bones. NIAMS points out that both muscle and tendon problems can cause knee pain due to tendinitis, or inflammation of a tendon, ruptured tendon, inflammation, sprains and muscle weakness. Weakened muscles around the knee joint can cause it to become unstable and susceptible to ligament injuries and other problems. Physiotherapy to work these muscles can help to prevent pain and inflammation in the knee joints.
