There are two menisci within the knee both on the outer aspect (lateral meniscus) and the inner aspect (medial meniscus). The menisci lie between the two main bones within the knee, the tibia and femur. These important substances act as shock absorbers within the knee and are made up of special material that allows the knee to withstand the force of weight-bearing while walking and performing sports. The menisci are thin towards the inside and thicker towards the periphery. The menisci can commonly be injured during pivoting activities or sports. The medial meniscus is more commonly injured.
A injury to the meniscus can cause a tear to occur that can cause knee pain overlying the meniscus or joint line of the knee where the injured meniscus is located. Meniscal tears can also cause swelling, locking, or instability of the knee.
A meniscus tear is most commonly diagnosed with a careful history and physical examination by your orthopaedic physician. Pivoting activities or sports are the most common mechanism for injury to the meniscus. Meniscal tears can also occur from wear and tear as someone ages. Swelling of the knee generally occurs several hours to days after the injury and pain generally does not respond to conservative treatment.
X-rays of the knee are generally required to rule out any other causes of knee pain. An MRI is generally most helpful to image the menisci and determine how much damage has occurred.
A meniscus tear is generally treated with arthroscopy to either repair or remove the damaged area. An MRI can determine the extent of the tear and help the physician determine if the tear is repairable. Arthroscopy is performed on an outpatient basis in a hospital or surgical outpatient center. Occasionally meniscus tears are treated conservatively, i.e. without surgery, especially if patients have minimal or no pain or already have advanced arthritis within the knee that can be controlled with conservative options for arthritis.