Most people have had a minor knee problem at some time. Most of the time our body movements don't cause problems. But sometimes symptoms develop from everyday wear and tear, overuse, or injury. Knee problems and injuries most often occur during sports or recreational activities, work-related tasks, or home projects.
The upper and lower bones of the knee are separated by two discs (menisci). The upper leg bone (femur) and the lower leg bones (tibia and fibula) are connected by ligaments, tendons, and muscles. The surface of the bones inside the knee joint is covered by articular cartilage. It absorbs shock and provides a smooth, gliding surface for joint movement.
Knee problems are often caused by an injury to one or more of these parts of the knee. But they may be caused by things other than injuries. Some people are more likely to have knee problems than others. Many jobs, sports and activities, getting older, or having a disease such as osteoporosis or arthritis increase your chances of having problems with your knees.