MENISCUS TEARS: OVERVIEW
The menisci (singular: meniscus) are semicircular shock-absorbing pads of fibrocartilage within the knee that protect the smooth articular cartilage surfaces, provide structural support, and disperse the weight of the body over a larger area. A meniscus is most often torn in one of two ways, either traumatically or due to degeneration. Traumatic tears typically occur following a single twisting episode, resulting in immediate pain and swelling to the knee, whereas degenerative tears occur due to the brittle nature of an aging meniscus.
Not all meniscal tears produce symptoms. In fact, one classic study demonstrated that 36% of people with normal pain-free knees had evidence of meniscal tears on MRI.1 When symptoms do occur, they often include pain directly over the meniscus and swelling in the knee, at least initially. Depending on the size and type of the tear, they can also cause mechanical symptoms, such as “catching” or even “locking” of the knee. These are not necessarily just sounds that the knee makes. Rather, they refer to a disruption of the normal, smooth motion of the knee as it is flexed and extended. “Catching” refers to the sensation that something is briefly (for less than a second) getting “caught” during knee motion. After this brief moment, the knee is “freed up” and moves normally again. “Locking” occurs when the knee, either temporarily (more than a second) or permanently, cannot be fully bent or straightened due to a mechanical block inside the knee. If your knee becomes “locked” and does not allow for full knee motion, medical treatment should be sought immediately.
1. Zanetti M, Pfirrmann CW, Schmid MR, Romero J, Seifert B, Hodler J. Patients with suspected meniscal tears: prevalence of abnormalities seen on MRI of 100 symptomatic and 100 contralateral asymptomatic knees. AJR Am J Roentgenol. 2003 Sep;181(3):635-41.
Nels Sampatacos, MD
Orthopedic Surgeon and Sports Medicine Specialist
