A tear of the anterior horn of the lateral meniscus is damage to the front part of one of the two structures that act as shock absorbers between the thigh bone and the lower leg, explains The Steadman Clinic. Meniscus tears are either degenerative or acute.
There are two semicircular menisci in the knee joint; the lateral meniscus is located on the outside, and the medial meniscus is on the inside, notes The Steadman Clinic. The front part of each of these is called the anterior horn, while the back part is referred to as the posterior horn. An acute tear occurs when the knee is bent and twisted while it is bearing weight, and a degenerative tear is the result of aging. Sixty percent of people over 65 have minor tears that sometimes cause no symptoms. Damage to the medial meniscus is more common because it is attached to a ligament, while the lateral meniscus is more mobile because it has no attachment.
Tears in the menisci are categorized according to their shape, their location, how complete they are and whether or not they are stable, according to The Steadman Clinic. The location of a tear determines whether or not it can heal, and the pattern of tearing influences how a doctor treats it. A complete tear goes all the way through the meniscus, while a tear that is still partly attached is considered incomplete. A stable tear may heal without treatment, but an unstable tear usually requires surgery.