Meniscal injuries are an important source of knee pain.

They often occur in the following triad:

• Meniscal injury
• ACL (anterior cruciate ligament) tear
• MCL (medial collateral ligament) tear

• Conservative Treatment
• Meniscectomy.  Currently out of favor.  Current treatment favors removing the absolute minimum of tissue .
• Suture of Meniscal Tears.  Often gives good results with peripheral lesions.  Not likely to be successful in central lesions as poor blood supply prevents effective healing.

A: The menisci are small pieces of cartilage located between the two bones of the knee (the 'femur' and the 'tibia'). There are two menisci:

• Lateral Meniscus (towards the outside of the knee)
• Broad and circular shaped
• More  mobile than the medial meniscus,
• Much less frequently injured than the Medial Meniscus (10x less)
• Medial Meniscus (towards the inside of the knee)
• C-shaped
• Less mobile
• Much more likely to be injury (10x more)

1. Act as a shock absorber [this assumption is being challenged, and may not be 100% correct]
2. Fill in the space between the two major bones of the knee (tibia and femur)
3. Act as a "Windshield Wiper" to move the joint fluid along the surface of the joint, this may aid in joint nutrition
4. Proprioception (the bodies perception of the joint in space)
5. Aid in locking of the knee, when the knee is in full extension, to allow standing with mimimal effort
6. Redistribution of the forces of the knee across the surface areas of the joint.  The normal meniscus may carry between 40 and 70% of the load on the knee.
7. Form mechanical spacers to stabilize the knee

Dr Frankenstein's Science Experiment #3256

Q: How does a meniscus become injured ?

A: Menisci can become injured by a number of events. Injury can be due to a single episode, long-standing 'degenerative' disease, or a combination of the two. In general movements such as twisting, squatting, and pivoting are most likely to cause injury.

Injury to the menisci tends to peak at about 21-40 years of age in men. In women, most injuries occur between 11 and 20 years.  Nonetheless, menisci do degenerate with age, and become more prone to chronic injury

Ligament injury is often a cause of meniscal injury, in particular, anterior cruciate ligament injuries have a high proportion of meniscus injury.  This is true in that the meniscal injury may occur at the same time as the ligament injury, or, chronic ligament laxity may lead to increased risk of meniscal damage.

Some people simply have an abnormal meniscus which is predisposed to injury

Certain activities, especially those requiring repetitive rotational stress may cause injury.  Twisting while under compression is particularly likely to cause injury to the poorly vascular mid-portion of the meniscus.  When these tears extend to the edge of the meniscus they form "bucket handle" tears.

Q: What are the most common symptoms of meniscus injury ?

A: Five major symptoms may occur, but may not be present in every person:

1. Pain
• may be aggravated by twisting, pivoting, changing directions
• crouching may make the pain worse
• pain may be present only at night
2. Locking
• an inability to move the knee past a certain point
• often painful, with a sudden onset
• may need an emergency room visit if movement not possible
3. Catching, grinding, or popping
4. Swelling (usually minor or absent)
5. Feeling of weakness, like the joint may give way.

A:  Diagnosing a meniscal injury is not always easy.  In general, it will require a combination of appropriate symptoms, a physical exam supporting the diagnosis, and nearly alway some sort of diagnostic test.

In addition to the symptoms discussed above, a physician may perform one of the physical examination tests:

1. McMurray Test:  Most likely the most commonly used test for meniscal injury.  It is performed in the following manner:
1. With the patient lying on the back, the knee is flexed fully.  Full flexion is necessary for this test, so it cannot be performed if severe pain, muscle spasm, or effusion is present.
2. During the flexion process,  the knee is rotated initially internally.  The fingers are held on the  medial aspect of the knee.  A palpable clunk accompanied by joint pain is a positive test.
2. Steinman Test
1. Part I:  The patient is seated with the leg held at 90degrees flexion.  The test is positive if internal rotation gives lateral joint line pain and external rotation gives medial joint line pain.
2. Part II: The test is positive if the joint line tenderness moves anteriorly with knee extension and posterior with knee flexion ( remember that the meniscus tends to follow the tibia more closely than the femur)
3. Apley Test
1. The patient lies prone.  The knee is flexed to 90degrees.
2. Pain ilicited by a grinding motion accompanied by downward pressure suggests meniscal injury.
3. The same grinding motion is performed accompanied by upward pressure.  Pain here suggests ligament injury.
4. Pivot Shift Test (this test is somewhat difficult to describe or perform)
1. The patient lies on the back.  The knee is flexed to 45degrees.
2. The knee is flexed slightly while a valgus stress is given
3. The knee is extended slightly while a varus stress is given
4. A positive test produces a shift/pivot or grinding sensation
5. Duck Walking (A simple test but remarkably good for detecting meniscal injury)
1. The patient bends down by flexing at the knees and with the legs pointed at approximately 45degrees ahead
2. Attempting to walk foreward in this position may cause pain in patients with meniscal pathology, and may be impossible in those with knee effusions.
6. Finocchietto Sign
1. A snapping noise or palpable jump in the femur experienced when performing the anterior drawer sign.
2. Caused by a trapping of the meniscus between the femur and tibia during flexion and extension

• Plain Xrays.  Useful for ruling out fracture, but often desceptively normal
• Arthrogram.  Injection of dye into the joint followed by Xrays.  If a tear is found on arthrogram, it is good evidence of meniscal injury.  Negative arthrograms are somewhat more difficult to interpret.
• CT (computed tomography) scan:  Accurate and non-invasive.  May miss small undisplaced tears.
• MRI (magnetic resonance imaging).  Expensive but accurate
• Arthroscopy:  Extremely accurate, the "Gold Standard" for meniscal investigations.  However, since the test is so sensitive, findings must be correlated with history and physical examination.  The simple presence of a meniscal lesion on arthroscopy is not an automatic indication that the injury is the cause of the patients symptoms.