Sunday, January 23, 2011

Treating and Preventing Meniscus Injuries - Part 1

The word meniscus is derived from the Greek word that means “Crescent” as in a crescent-shaped moon. The menisci in your knee are crescent-shaped fibro-cartilaginous structures that provides stability, shock absorption, nutrition, and joint lubrication while acting to distribute your weight across your knee joint.
The bones of your knees are covered with a layer of very smooth cartilage. This cartilage allows for gliding, reduced friction, and freedom of motion. The menisci of your knees are located between these cartilaginous surfaces and act to provide stability and even weight distribution. Forty to sixty percent of the force in the lower extremity is transmitted through the menisci. Without functional menisci, the joints of the knees would soon degenerate.
Each knee has two menisci - a lateral meniscus and a medial meniscus. Both menisci have a concave shape on the top and are flat on the bottom to create a wedge shape. This wedge keeps your thigh bone [ femur] from slipping off your shinbone [ tibia].
The lateral meniscus has an anterior and posterior horn. The popliteus muscle attaches directly to the posterior horn of the lateral meniscus. Thus, any tension or restrictions in the popliteus muscle directly affects the function of the lateral meniscus.
The medial meniscus also has an anterior and posterior horn. The semimembranosus muscle (a tendon extending from the hamstring) attaches to the posterior horn of the medial meniscus. Any tension or alteration in function of the hamstring muscles affects the function of medial meniscus. Fibers from the anterior cruciate ligament (ACL) blends into the anterior horn of the medial meniscus. A medial meniscus injury often occurs when there is an ACL tear. The medial meniscus is injured 5 to 7 times more often than the lateral meniscus since the medial meniscus is less mobile than the lateral meniscus.
Menisci injuries
Meniscus tears often occur when playing sports such as football, basketball, soccer, or rugby. Quite often, the injury occurs during a torsional motion in which the player’s knee is flexed while the foot is planted on the ground. Essentially the meniscus is torn due to the compressive forces that occur with rotation when the meniscus are pinched between two bones (tibial and femoral condyles).
Meniscus tears can also occur due to the slow degeneration that occurs with aging when the meniscus becomes less pliable and is easily torn. This usually happens to individuals over 60 years old.
Meniscus injuries, on the outer edges of the meniscus, can be very slow to heal due to poor circulation in the area. Meniscus injuries that occur within the center of the meniscus do not have the ability to heal themself since the center of the meniscus does not have a blood supply - it is avascular - without circulatory input. Without a good blood supply, nutrients required for healing are not supplied to the area and waste by-products are not removed. In a severe meniscus injury, loose pieces of cartilage (articular cartilage) may actually break off within the joint. These pieces can cause considerable damage to the knee joint, and lead to degenerative arthritis.
Surgical solutions for Injuries to the Menisci
Sometimes meniscus surgery is necessary. When surgery is performed, most surgeons will remove only a part of the meniscus. Removal of the entire meniscus will soon result in the development of osteoarthritis since there will be 235% increase in the stress experienced by the bones touching each other at the knee joint (tibiofemoral contact area). Arthroscopic surgery (where they remove a small section of the meniscus) can be performed if the damage is confined to the peripheral rim of the meniscus. Complete removal may be recommended by the surgeon if the damage is to the center of the meniscus (non-vascularized area).
Treating and Preventing Menisci Injuries – see the next installment of this blog for more information about how you can treat and prevent menisci injuries. For more information about knee injuries, visit the following sites:
Treating Meniscus Injuries Part 2

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1 comment:

  1. Tears come from the heart and not from the brain.
    See the link below for more info.