Arthritis of the knee
Osteoarthritis is the most common type of arthritis to affect the knee. This condition involves wear-and-tear damage to your knee’s cartilage.
Two special pieces of cartilage (menisci) provide cushioning and stability inside your knee joint. Meniscus tears can happen suddenly during sports or they may result from degenerative damage over time.
Anterior cruciate ligament (ACL) tears
ACL tears are among the most common sports injuries to affect the knee. The ACL is one of four main ligaments in your knee. This ligament can become stretched or torn during common sports movements, like stopping suddenly and changing direction (cutting).
Other sports injuries
Knee injuries that occur during sports often involve damage to more than one part of the knee. For example, meniscus tears and ACL tears often happen together. Other sports injuries that affect the knee include fractures, tendonitis, and sprains.