What is a Knee Meniscus?
Your knee meniscus is fibrocartilage that separates the thigh bone (femur) from your shin bone (tibia). Most people refer to your knee meniscus as your knee cartilage. Each knee joint has a medial meniscus and a lateral meniscus.
Your knee meniscus has unique shapes. They are a wedged, kidney shape.
The wedged shape assists with your knee’s rotational stability. 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 Knee Meniscus Tear?
Your knee meniscus is usually torn traumatically in the younger population by twisting on a slightly flexed knee.
The traumatic type of meniscal injuries is 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, arthroscopic knee surgery attended both the meniscal repair and repairing the damaged joint surface.
Depending on the type of meniscus tear, meniscus repair may be complicated. A neglected large meniscus tear is undesirable. Some knee specialists believe the damaged meniscus could lead to premature degenerative bony (arthritis) changes potentially.
How Do You Know if you have Torn a Knee Meniscus?
Torn meniscus symptoms typically start with a mechanism of injury that involves a history of a painful twist occurring on a slightly flexed knee. However, degenerative meniscus tears can slowly present with signs and symptoms.
Signs & Symptoms of a Knee Meniscus Tear
You may also experience clicking, popping, or locking of the knee. Pain along the knee joint line and joint swelling frequently accompany.
The 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?
An MRI scan is the most accurate non-invasive test to confirm a meniscus tear. X-rays do not show a meniscus tear.
Can a Meniscus Tear Heal on its Own?
Meniscus tear healing is dependent upon your meniscal blood supply, which 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.
The red zone has a blood supply, which means it can heal naturally. A “longitudinal tear” is an example of a meniscal tear that is likely to heal naturally. The outer edge of the meniscus has a blood supply from the synovial capsule. Lateral meniscal tears may improve without the need for surgery.
The white zone doesn’t have a blood supply and won’t heal naturally. 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 to remove the torn component.
What Happens if you Leave a Torn Meniscus Untreated?
An untreated meniscus tear can deteriorate and may come loose within the knee joint. These fragments can result in knee locking or giving way. Untreated meniscus tears can also increase in tear size and extend the damaged area of the meniscus.
Treatment Options for a Knee Meniscus Tear
A small meniscus tear, or a tear in the red zone, will usually respond quickly to physiotherapy treatment.
One of the primary roles of your meniscus is shock-absorption. Luckily, the other vital shock absorbers around your knee are your muscles. Researchers have discovered that if you are strengthening your leg muscles, your bone stresses will reduce as your muscle strength improves and your knee becomes more dynamically stable.
Your physiotherapy treatment will aim to:
- Reduce pain and inflammation.
- Normalise joint range of motion.
- Strengthen your knee: esp quadriceps (esp VMO) and hamstrings.
- Strengthen your lower limb: calves, hip and pelvis muscles.
- Improve patellofemoral (knee cap) alignment.
- Normalise your muscle lengths Improve your proprioception and balance Improve your technique and function, e.g. walking, running, squatting, hopping and landing.
- Minimise your chance of re-injury.
Meniscal injuries are commonly associated with other knee injuries, which may also require treatment.
How Long Does It Take For a Meniscus to Heal Without Surgery?
Your meniscal tear will commonly take up to six or eight weeks to fully heal if the injury is in the red zone. As mentioned previously, some meniscal tears will require surgery. Your physiotherapist will guide you as to what is most likely for your knee injury.
It is important to avoid activities and exercises that place excessive stress through your meniscus and further delay your healing. In some cases, your physiotherapist may advise you to keep weight off your knee. In these instances, we may recommend crutches. Everyone is different, so be guided by your physiotherapist.