Your knee is your anatomical pulley between your femur (thigh bone) and tibia (shin bone) and fibula (small bone beside your tibia).
Cartilage protects the ends of your bones and occupies the space between your bones. Consider cartilage as a cushion to prevent your bones from grinding. Your cartilage is filled with synovial fluid.
The end of your femur closest to your knee is enclosed by your femoral condyle. It is referred to as your articular cartilage. It protects the end of your femur. Aging can cause osteochondritis dessicans (cracks or fractures) in your articular cartilage.
You also have lateral and medial meniscus within your knee joint. These are cartilaginous material that have very little blood supply. They dry out with age and do not absorb as much fluid. Excessive rubbing of the end of the femur and tibia may cause these cartilaginous fibers to wear out. Soon there is bone on bone contact. This is the origin of osteoarthritis.
Ligaments connect your bones together. Your lateral and medial collateral ligaments along with your anterior and posterior cruciate ligaments help to bring your femur in line with your tibia. Damage to your anterior cruciate ligament (ACL) may be a traumatic injury.
Posterior cruciate ligament (PCL) impairment is generally not so severe. Several muscles extend your knee. Your quadriceps allow you to extend from a sitting position to a standing one. You can jump, and add power to your kicks using your extensors. These muscles (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius) are on the front of your thigh. The only one of these muscles that crosses your hip is your rectus femoris.
Your hamstrings, in the back of your upper leg generate knee flexion. These muscles are generally weaker than your quadriceps. If your hamstrings are more than 3 times weaker than your quadriceps, then you have a muscle imbalance which may precipitate knee problems. It is a good idea to strengthen your hamstrings (biceps femoris, semimembranosus, semitendinosus) using resistance exercise.
On the inside of your knee closest to your groin, you have muscles called adductors. These muscles (adductor magnus, longus, brevis, and gracilis) help to pull your leg toward your body.
On the outside of your knee you have abductors. These muscles (tensor facia latae, gluteus medius) pull your leg away from your body. Your adductors and abductors help to stabilize your movements when you flex and extend your knees from a standing position. There are a variety of known and unknown causes of knee pain. Tendinitis is generally caused by overuse - jumping (especially landing), and running down hill.
Bursitis is irritation of the bursae sac in your knee. It may be caused by falling on your knee or prolonged kneeling such as is required of a baseball catcher.
Ligament damage may be minor (1st degree) on a continuum to severe (3rd degree). Your ACL may be injured by twisting and getting stuck in external rotation. Your PCL may be damaged when you hyperextend your knee. But when your PCL is injured, usually this is accompanied by medial collateral ligament (MCL) or ACL strain. Your MCL and lateral collateral ligaments (LCL) may be damaged by a blow to the outside or inside of your knee, or knee rotation when your foot is planted. Cartilage problems may be recognized by pain, clicking, or locking of your knee. But a loud "pop" is usually the ACL. Meniscal tears may be caused by a sudden twisting, or by repeated deep squats. When you extend your knee, there is a slight lateral rotation of your tibia and femur. This is termed the "home screw mechanism." Some meniscus tears cause the knee to lock up because the torn meniscus gets caught in rotation. There is a 4 to 1 ratio of women to men who injure their ACL in college basketball. Possible explanations include weak hamstrings, poor pre-competitive conditioning, lack of pre-preparation agility drills such as plyometrics, and tracking problems in women because of their greater Q angle (wider angle from hip to knee).
Single leg, open chain exercises to strengthen the muscles surrounding your knees include leg extensions and leg curls. If your knees feel uncomfortable performing leg extensions, omit the last 15 degrees of extension. Double leg, closed chain exercises are closer to real world activity. These movements include wall sits, wall glides, and wall squats. Practice quarter squats, half-squats, and lateral and diagonal squats.
Your physician can help you with these exercises. After mastering open chain and double leg closed chain exercises, try single leg closed chain activities. These include partial lunges, stationary lunges, and full translatory lunges. If you are successful with these, you may attempt diagonal lunges, and one-leg partial squats. When your muscles, tendons, and ligaments are strong enough, attempt to balance on one leg. Then close your eyes and continue. Find a balance board or wobble board to activate stabilizer muscles. Use your SportCord to provide extra resistance for squats and lateral movement.
