Diagnosing a Meniscus Injury
The most commonly injured part of the knee is the medial collateral ligament (MCL), followed by the anterior cruciate ligament (ACL) or both, then the medial meniscus, and the lateral collateral ligament (LCL). Medical professionals (such as an orthopedic surgeon or physician) will be able to assess and test whether you have a meniscus injury, and then will determine what type you have through a variety of processes. It is more difficult to diagnose a lateral meniscus tear than a medial meniscus tear, because of its tear shape and location (it may go unnoticed until it is much larger).
To help your doctor achieve a proper diagnosis, he/she will begin with a medical history about you, your current condition and symptoms. They will inquire about the intensity of your present pain, the duration of your symptoms and the limitations you are experiencing. Details about what instigated the problem, when it started, and whether or not you have ever had treatments for this or a similar condition in the past, are very helpful in assessing your injury.
A physical examination will be performed to determine if you have any signs of a meniscus injury or other knee injuries. Your doctor will visually assess and palpate (feel) the bones and soft tissue in and around both of your knees to evaluate symmetry and recognize differences. This will identify any abnormalities, such as mild or severe inflammation, bone deformity, and atrophied muscles. He/she will press on the injured side of your knee joint to test for point tenderness and help determine the location of your injury or tear. He/she may ask you to complete a series of knee and leg movements such as moving your knee from a straight to bent position (or vice versa), or rotating your knee to see what motions cause pain, weakness, instability and/or grinding, catching, popping or locking. These sounds or restrictions will often indicate a tear. Your knee will also be inspected for fluid, swelling and warmth.
Most Common Meniscus Injury Diagnostic Tests:
A medical professional will sometimes recommend diagnostic testing to obtain more detailed information, and assess the amount and/or type of damage done to your knee and meniscus. There are a variety of different tests available to help them analyze the situation; however these will be dependent on your injury.
X-rays will provide an image of the overall structure of your knee. It is helpful in identifying abnormal bone shapes, fractures, arthritis, and degeneration (wear and tear) on the joint. It can identify a discoid meniscus, or loose bones and bone abnormalities that may mimic a torn meniscus.
MRIs (magnetic resonance imaging) will provide more detailed information and will help to evaluate the soft tissues in and around your knee joint (muscles, tendons, ligaments, menisci, other connective tissues). It can identify ligament and meniscal damage, and help to determine the extent of your injury, the displacement and degree of your tear, fluid on your knee, a discoid meniscus and/or other associated conditions.
CT or CAT scans (computerized tomography) will be used to provide a more thorough, 3-dimensional assessment of the bones and soft tissues in and around your knee joint.
Further diagnostic tests such as an ultrasound, electromyogram, or arthroscopic surgery can be used to determine the degree and location of your injury if required.
Meniscus Tear Descriptions:
The severity of your meniscus tear will vary depending on which meniscus is injured and the location, type and shape of the tear.
Blood supply to the injured area is critical in healing; therefore where the tear is located will determine its ability to heal. The meniscus can be broken into red (outer), middle and white (inner) zones; tears in the red zone have the best chance of healing because they have more access to blood supply.
- Red-on-Red meniscus tear is in the red zone (the outer part of your meniscus and knee joint). Both sides of the tear are in tissue that receives a lot of blood supply; as a result it experiences a quick healing rate.
- Red-on-White meniscus tear is between the red zone and the middle (includes the outside rim and center portion of your meniscus). This type of meniscus tear heals slowly, as the outer edge of the tear generally receives good blood supply and the inner part of the tear doesn't.
- White-on-White meniscus tear is in the white zone (the middle and inner part of your meniscus). It is amongst all the bones and ligaments and receives little blood supply; therefore it has a poor healing rate.
Your knee joint can also be divided into the anterior horn (mobile, curved portion at front of meniscus), the posterior horn (less mobile, curved portion at back of the meniscus) and the body (middle section of the meniscus, thicker on outside and thinner on the inside). There are 3 types of meniscal tears you can experience in these locations:
- Partial meniscus tear (partly attached to your meniscus) tends to be smaller and more stable because it stays connected to the front and back of your knee. It doesn't move about freely, therefore it can occasionally heal well on its own.
- Complete meniscus tear (tissue separates from your meniscus and tear goes all the way through) tends to be larger and less stable, because it hangs by a thread of cartilage. The torn part moves about in your joint, which can lead to further complications and damage if not treated.
- Degenerative meniscus tears have frayed edges on the inner rim, which can eventually tear in multiple directions and can lead to a completely degenerated meniscus. A piece in the body of the meniscus often moves about in your joint, which usually has a horizontal component.
The medial meniscus is more often injured than the lateral meniscus and involves more symptoms. Medial meniscus tears generally occur in the posterior (back) horn, which is prone to injury and harder to manage than tears in the body, the anterior (front) or on the periphery (outside). The posterior horn is more contained and carries more of the load than the other areas. It is also difficult to reach because bones are in the way. Peripheral tears occur on the outside near the attachment to the knee capsule. They receive a lot of blood supply, so they are easily repaired. These tears often occur in conjunction with an ACL or MCL injury.
Meniscus Tear Shapes:
The pattern of your meniscus tear is important because it will determine the type of treatment you receive (some tears will heal on their own, some can be treated surgically and some canąt be fixed). Tears come in many shapes and sizes however there are 3 basic shapes for all meniscal tears: longitudinal, horizontal and radial. If these tears are not treated, they may become more damaged and develop a displaced tear (moving flap of meniscus). Complex tears are a combination of these basic shapes and include more than one pattern.
A Longitudinal meniscus tear (circumferential tear) extends along the length of your meniscus and does not go all the way through. This tear divides your meniscus into an inner and outer section; however the tear generally never touches the rim of the meniscus. It tends to be more medial than lateral, and results from repeated movements. It generally starts as a partial tear in the posterior horn, which can sometimes heal on its own. However if it doesn't heal properly it can lead to a displaced longitudinal tear, known as a displaced Bucket Handle tear. This is a complete tear that goes all the way through and is located near the inner rim of your medial meniscus; it is often associated with a radial tear. This tear accounts for 10% of all meniscus tears, and causes your knee to lock in flexion. It is seen most often in young athletes, and happens in conjunction with 50% of ACL injuries.
A Horizontal meniscus tear (cleavage tear) starts as a horizontal split deep in your meniscus. This tear divides your meniscus into a top and bottom section (like a sliced bun). It is often not visible, and moves from the posterior horn or mid section to the inside of your meniscus. This tear is rare and often starts after a minor injury from rotation in the knee or degeneration. It occurs frequently in your lateral meniscus; however it is noted in both menisci. A displaced Horizontal Flap tear can develop if your tear is overlooked or left alone. This type of tear is horizontal on the surface of your meniscus and creates a flap that flicks when your knee moves. It is a result of a strong force that tears your meniscus from the inner rim; it can easily become a complex tear. If this tear extends from the apex of your meniscus to the outer rim, you may develop a meniscal cyst (a mass that develops from a collection of synovial fluid along the outside rim of the meniscus).
A Radial split meniscus tear (free-edge transverse tear) starts as a sharp split along the inner edge of your meniscus and eventually runs part way or all the way through your meniscus, dividing it into a front and back section (across the middle body instead of down the length). This tear generally occurs between the posterior horn and middle section and is seen frequently in your lateral meniscus. A small tear is difficult to notice, but when it grows and becomes a complete tear it will open up and look like a part is missing. This is called a Parrot's Beak tear (displaced radial tear with a curved inner portion). It generally occurs in the thicker portion of your lateral meniscus. As it gets larger, it will catch or lock more frequently, and prevent your meniscus from protecting the cartilage during weight bearing. This tear is a result of a traumatic event or forceful and repetitive stress activities; it is often associated with other injuries. Young athletes tend to suffer from combination tears called radial/parrot beak tears (the meniscus splits in 2 directions).