Menisci are found in a person's knee joints, lying on top of the uppermost end of the shin bone. Each knee has a lateral pad of cartilage, or meniscus, toward the outer side of the knee joint and a medial meniscus on the inner side of the knee joint. Signs and symptoms of a meniscus tear include pain, swelling, an inability to bear weight on the injured knee and a clicking or catching of the joint.
Ligament-Related Tears
Each medial meniscus is attached to the medial collateral ligament, the anterior cruciate ligament, or ACL, and the semimembranosus hamstring muscle, according to Peggy Houglum in her book, "Therapeutic Exercise for Musculoskeletal Injuries." The medial menisci are, therefore, more prone to tears compared to the lateral menisci; once a person's ACL is disrupted, the chances of tearing the medial menisci increase. The lateral menisci are not attached to a collateral ligament though the lateral menisci usually tear at the same time as an injury or tear to the ACL. Ligament-related injuries typically cause vertical tears.
Tear to the Posterior Horns
All menisci have an anterior horn or anterior segment, body or middle segment, and a posterior horn or posterior segment. A person bears most of his weight on the back portion of the knee joint, which is, therefore, the most common site for a meniscus tear, according to SportsMedicineBulletin.com. Most meniscus tears are vertical or oblique and may prevent complete straightening of the knee if a fragment of the tear is jutting out from the meniscus.
Age-Related Tears
Traumatic meniscus tears often occur during twisting or pivoting forces on the knee in young, active persons. Such traumatic tears primarily occur in the anterior horn and the body of the meniscus, according to Houglum. Degenerative tears are usually horizontal tears and occur as a person ages, with little chance of healing, typically in the posterior horn. The inner perimeter of the menisci have less blood supply than the outer perimeter; as a person ages, the menisci have even less blood flow.
References
- National Library of Medicine: Meniscus Tears
- "Therapeutic Exercise for Musculoskeletal Injuries"; Peggy Houglum; 2005
- Sports Injury Bulletin: Meniscal Tears Treatment Review
- Steadman-Hawkins: Meniscal Injuries
- "Examination of Musculoskeletal Injuries"; Sandra Shultz, Peggy Houglum and David Perrin; 2005
