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Meniscal Tear Variations: Why You Can't Compare Apples to Oranges

Something we frequently hear in the office after someone has been diagnosed with a meniscus tear is, "My friend had a meniscus tear and they were able to fix it" or "My sister had a meniscus tear and she didn't need surgery".  

Comparing your meniscus tear to someone else's is like comparing apples to oranges.  Your menisci are unique structures.  Depending on your age and activity level your menisci are susceptible to a variety of tears.  

First things first, here's a quick anatomy lesson to familiarize yourself with your menisci:

The meniscus (plural: menisci) is a C-shaped piece of cartilage that sits on top of your tibia (shin bone) and acts as a shock absorber between your femur (thigh) and your tibia.  Each knee has two menisci, one on the lateral (outside) aspect and one on the medial (inside) aspect of your knee.  Your meniscus also contains three zones which I will explain further since they can determine if your tear is repairable or not.  

The Red-Red Zone is the peripheral outer 1/3 of your meniscus.  It is called the red zone because it receives the most blood supply.  

The Red-White Zone is the middle 1/3 of your meniscus.  It has some blood supply, but not as much as the red zone.

The White-White Zone is the inner most 1/3 of your meniscus.  It is called the white zone because it does not have any blood supply and is white in appearance.  It is nourished by the joint fluid in your knee.

As mentioned above, all tears are not equal.  There are 7 common types of meniscus tears and depending on their size and location in the meniscus determines whether they are repairable. 

Radial Tear- This is the most common type of meniscus tear; it starts in the white zone and tears towards the red zone.  There is also a variation of the radial tear called the Parrot Beak Tear which is more curved and resembles the beak of a parrot.  Due to lack of blood supply in the white zone, these tears do not heal and often require a surgery.  Surgery consists of a knee arthroscopy (scope) to trim the torn portion.  

Incomplete tears- Incomplete tears can also be referred to as intrasubstance tears.  They are often due to normal wear and tear in the knee and may be an indication of early degeneration of the meniscus.  Think of your meniscus like a rubber gasket.  When a rubber gasket is new it's very pliable.  As a rubber gasket ages it become stiffer and can crack.  The rubber gasket analogy can be used to describe your meniscus as it ages.  An incomplete tear is like a rubber gasket cracking with age.  These tears do not always require surgery.  

Flap Tear- A flap tear is when a piece of the meniscus breaks off, creating a fragment that can cause painful catching and locking in the knee.  Surgery is usually indicated to trim or repair the torn piece so it does not keep catching in the joint.  

Horizontal Tear- A horizontal tear, also known as a cleavage tear, presents as a delamination of the horizontal layers of meniscus fibers, similar to layers of plywood coming apart.  Another good way to envision this tear is to picture a piece of pita bread with the tear as the slit in the bread. These tears are common in the aging meniscus and do not always cause mechanical or catching symptoms. They do not have a good healing potential and are usually trimmed off.  

Vertical (longitudinal) Tear. This type of tear occurs vertically along the cirucumferential fibers of the meniscus, anywhere within the meniscus zones. It can lead to painful catching sensation. These tears usually occur during a twisting injury.  An extended version of this tear is the Bucket Handle Tear, which is usually in the thicker part of the meniscus, where there is better blood supply (red-red or red-white zones). The larger bucket handle piece can flip over like a handle on a bucket, hence the name.  The displaced piece blocks the knees natural motion causing your knee to lock. Depending on the location of the vertical tear, will determine whether the tear is trimmed or flipped back and sewn with suture if it is in the area of good blood supply.

Complex Tear- A complex tear is a combination of multiple tears, usually involving a radial and horizontal tear.  This type of tear usually involves trimming the torn portion but may also include a repair depending on type and locations of the tears.  

Root Tears- These tears occur at the attachment to the bone at its anchor point. These tears are ominous with poor prognosis, since they are equivalent to the loss of the entire meniscus and its protective function to the joint. Root tears can be difficult to diagnose and precipitate arthritis if neglected. The best approach is to fix them early to give the knee the best chance to delay arthritis. Some root tears are degenerative and cannot be fixed.

If you're having knee pain, it's always best to be evaluated by an orthopedic specialist.  Your doctor will be able to perform several tests in the office to determine what movements irritate your meniscus.  Ultimately given your symptoms and your exam finding your physician will most likely order an MRI.  Based on your MRI findings your doctor will determine a plan of care.  

After reading this article you can see that there are many different types of meniscal tears so comparing then is like comparing apples to oranges or more appropriately pita bread to parrot beaks!




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