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Basics
Description
- The menisci are fibrocartilaginous structures between the femoral condyles and tibial plateaus.
- Each meniscus has a body, anterior and posterior horn.
- The menisci help stabilize the knee, lubricate, and distribute forces across the joint.
- There are acute/traumatic and degenerative meniscal tears.
- The inner 2/3 of the menisci are avascular and heal poorly after injury.
Geriatric Considerations
Meniscal tears in older patients are typically due to chronic degeneration.
- Meniscal injuries are rare in children <10 years old.
- Meniscal tears in children are often due to a discoid meniscus (anatomic variant with thicker and wider meniscus).
- MRI is less sensitive and specific for diagnosing meniscal tears in children <12 years of age.
Epidemiology
- More common in the 3rd to 5th decades of life
- More common in males
Incidence
Medial meniscus more commonly injured
Prevalence
One of the most common musculoskeletal injuries
Etiology and Pathophysiology
- Acute/traumatic tears occur due to a twisting motion of the knee with foot planted.
- More common <40 years old
- Degenerative tears occur with minimal trauma.
- More common >40 years old
Genetics
Presence of a discoid meniscus increases the risk for a meniscal tear. No specific gene locus has been identified.
Risk Factors
- Acute/traumatic:
- High degree of physical activity (especially cutting sports)
- Anterior cruciate ligament (ACL) insufficiency
- Degenerative:
- Increased age (>60 years), male
- Obesity
General Prevention
- Treatment and rehabilitation of previous knee injuries, particularly ACL injuries
- Strengthening and increased flexibility of quadriceps and hamstring muscles
Commonly Associated Conditions
- Acute/traumatic:
- ACL is concomitantly torn in 1/3 of cases.
- Medial and lateral collateral ligament tears
- Degenerative:
- Baker cyst—strong association with medial meniscal tears
- Osteoarthritis (OA)—degenerative tears can be considered as an early stage of OA in older patients.
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