What is a Meniscus?
Your knee meniscus is a fibrocartilage that separates thigh bone (femur) from your shin bone (tibia). It is commonly referred to as your "cartilage". Each knee joint has a medial meniscus and a lateral meniscus.
Your knee meniscus have unique shapes. They are a wedged, kidney shape.
Your meniscus act like a wedge to assist with the rotational stability created by the anterior cruciate ligament. The meniscus also acts as a shock absorber. As we walk, run, and jump the knee absorbs tremendous forces. Your meniscus helps to absorb these forces so that the bone surfaces are not damaged.
The amount of force increases exponentially as the speed of movement increases from walking to running to jumping. Your meniscus helps to disperse the compressive forces over the entire knee rather than isolating them.
What is a Meniscus Tear?
In the younger population, your knee meniscus is usually torn traumatically, by a twisting on a slightly flexed knee.
The traumatic type of meniscal injuries are most often sports-related. The meniscus can be torn anterior to posterior, radially (parrot beak), or can have a bucket handle appearance.
In the older adult, the tear may be due to a natural age-related degeneration of the meniscus or a rough arthritic femoral bone surface tearing into the softer meniscus. In this case, surgery may be required to attend to both the meniscal repair and to repair the damaged joint surface.
Depending on the type of meniscus tear, meniscus repair be complicated. A large meniscus tear that is inadequately treated may cause premature degenerative bony (arthritis) changes.
Signs and Symptoms of a Meniscus Tear
The history of a painful twist occurring on a slightly flexed knee will indicate the likelihood of a meniscus tear. You may also experience clicking, popping, or locking of the knee. These symptoms are usually accompanied by pain along the knee joint line and a joint swelling.
Clinical examination may reveal tenderness along the knee joint line. You will usually notice it is painful to squat.
Your physiotherapist or doctor will use McMurray's test and other clinical tests to confirm a meniscus tear diagnosis.
X-rays or MRI?
A MRI scan is the most accurate non-invasive test to confirm a meniscus tear. X-rays do not show a meniscus tear.
Does a Meniscus Tear Heal?
Meniscal blood supply is limited: your meniscus receives its nutrition from blood and synovial fluid within the joint capsule. Your meniscus has two distinct regions that affect their ability to heal. We call these the Red Zone and the White Zone.
Red Zone
The red zone has blood supply, whereas the the white zone doesn’t have a blood supply and won’t heal naturally. The outside of the meniscus has a blood supply from the synovial capsule. Lateral meniscal tears may heal without the need for surgery.
White Zone
The inside of the meniscus gets its nutrition from the synovial fluid. Due to this, tears of the inner meniscus do not usually heal due to a lack of blood supply to trigger an inflammatory response. These injuries often require surgery.
Treatment Options for a Knee Meniscus Tear
Read on about: Meniscus Tears
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