Your knee is made up of two main bones, the thigh bone, or femur, and lower leg bone, or tibia. These bones are held together by four main ligaments: the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), lateral collateral ligament (LCL) and medial collateral ligament (MCL). The meniscus is the rubbery cartilage that sits between these bones. When you step down, the meniscus acts as a shock absorber between the thigh bone, or femur, and the leg bone, or tibia. The bones come together to form a joint. It is at this joint that the bones move over one another to allow you to move about and move your body. At this joint the bones are lined with a hard substance called cartilage.
The patella is a disk shaped bone in the front of your knee. Your patella is attached to your tibia bone by a tendon called the patellar tendon. The kneecap also attaches to the quadriceps muscles which are the large muscles in the front of your thigh. The patellar tendon, quadriceps, and other soft tissue surround the patella in what we call a soft tissue envelope. Normally this soft tissue envelope is well balanced and strong allowing your knee to function without pain.
Normally your patella rides smoothly in a groove at the end of your thigh bone, or femur, when you bend and straighten your knee. The vastus medialis obliquus, or VMO, is important in maintaining this normal patellar movement and allowing balance of the soft tissue envelope around the patella. The movement of the patella in this groove at the end of the femur is called patellar tracking.
The largest joint in the body, the knee is also one of the easiest to injure. Knee problems can be caused by trauma, particularly from sports; physiologic issues like misalignment; degeneration from conditions like osteoarthritis; or just plain overuse. To learn about some of the most common knee injuries and conditions, view the videos, below.