History
A thorough subjective history can help the examiner choose the appropriate clinical tests to include in the physical examination. A complete understanding of the exact mechanism of injury helps to determine what type of meniscal involvement to look for. Initial symptoms may include the following:
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Acute joint-line pain may be described.
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Joint effusion gradually develops over a few hours. Patients with peripheral tears of the meniscus occasionally develop effusion rapidly (in minutes), secondary to a tear that is associated with hemarthrosis and is in the vascular outer one third of the meniscus. Stanitski et al studied 70 young patients with hemarthrosis after acute trauma and found that 47% had ACL tears and 47% had meniscal tears. In adolescents (aged 13-18 y), the rates were 65% and 45%, respectively. [17, 18]
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Locking is a common symptom after a meniscal lesion develops. Locking usually occurs at 20-45° of joint extension. If a torn fragment has been trapped within the joint, extension may feel limited against a rubbery resistance. Joint effusion or capsular involvement also may mimic signs of locking. A more reliable indicator of meniscal lesion is a click or snap after the joint unlocks.
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A sensation of giving way may occur. In true meniscal lesions, the fragment becomes lodged momentarily in the knee joint, causing a sense of buckling. This finding should be distinguished from the sensation of giving way due to joint instability (eg, ACL tear) or buckling secondary to decreased activity of the quadriceps femoris muscle.
Physical
During clinical examination, use the uninvolved leg for comparison with qualitative and quantitative findings for the involved leg. Examination should include inspection, palpation, ROM, gait, girth measurements, and tests for integrity of menisci and other structures of the knee joint. [19]
Inspection
Look for effusion, and check the state of healing of any scars or incisions. Effusion occurs in approximately 50% of the patients presenting with a meniscal tear. The presence of an effusion is suggestive of a peripheral tear in the vascular, or red, zone (especially when acute); an associated intra-articular injury; or synovitis.
Identify any signs of atrophy. Marked atrophy of the quadriceps femoris muscle, especially the vastus medialis oblique (VMO) segment, is sometimes an indication of long-standing meniscal injury; this is because the patient may be unwilling or unable to achieve full extension, and most tension is required of the VMO muscle at or near full extension.
Palpation
Localized palpable tenderness at the joint line often is present in patients with meniscal lesions because the coronary ligaments are irritated.
Assess joint lines for palpable pain. The location of the tenderness is not a sure sign of the type of lesion.
To assess effusion, perform the fluid shift test and evaluate for the presence of the fluctuation sign. The amount of effusion does not indicate the presence or absence of a meniscal lesion.
ROM and gait
The patient may have difficulty extending the knee fully if a meniscal tear blocks the motion.
Full flexion, as in squatting, may be painful or impossible because of a tear.
Assess the gait pattern, looking for deviations or compensatory movements.
Girth measurements
Girth (circumference) measurements allow for a general assessment of effusion and atrophy.
Swelling within the knee joint is measured grossly by a girth measurement taken at the joint line.
Measurements taken at 5 cm and 20 cm proximal to the base of the patella and 15 cm distal to the apex of the patella can provide an indirect indication of atrophy in the VMO segment, quadriceps femoris muscle, and calf muscles, respectively.
Tests
Perform stability tests for anterior, posterior, and varus-valgus motion to rule out additional involvement of soft tissue. Several special tests may be used to assess meniscal involvement. A positive result of any test does not by itself establish the presence of a meniscal lesion; along with the other objective findings, however, it can help to differentiate a meniscal tear from other possible knee injuries.
McMurray test
This test indicates tears of the middle or posterior horn of the meniscus.
With the patient supine and the hip and knee fully flexed, apply a valgus force and externally rotate the tibia while extending the knee. An audible or palpable pop or snap indicates a medial meniscal tear.
Lesions of the lateral meniscus are tested by applying a varus force and internally rotating the tibia during knee extension. The snap is produced as the torn fragment rides over the femoral condyle during extension.
A snap in extreme flexion is indicative of a posterior horn tear; a click at 90° of flexion indicates a lesion in the middle section of the meniscus.
Only 57% of meniscal root tears result in a positive McMurray test. [20]
Apley test
This test is used to distinguish between meniscal and ligamentous involvement.
With the patient in a prone position, the knee flexed at 90°, and the leg stabilized by the examiner's knee, distract the knee while rotating the tibia internally and externally. Pain during this maneuver indicates ligamentous involvement.
Then, compress the knee while internally and externally rotating the tibia again. Pain during this maneuver indicates a meniscal tear.
Bragard sign
This test may be used if anterior joint-line point tenderness is present.
To test for a medial lesion, the examiner extends and externally rotates the tibia, which displaces a meniscal lesion forward, if one exists. Palpable tenderness along the anterior medial joint line is reduced with flexion and internal rotation.
Bounce home test
The patient is supine, with his or her heel cupped in the examiner's hand.
The examiner fully flexes the knee and then passively extends the knee. If the knee does not reach complete extension or has a rubbery or springy end feel, the knee movement may be blocked by a torn meniscus.
Childress test
Instruct the patient to squat with the knee fully flexed and attempt to "duck walk."
If the motion is blocked, a meniscal lesion is indicated; however, pain in this position may indicate a meniscal tear or patellofemoral joint involvement.
Merkel sign
Instruct the patient to stand with his or her knees extended and to rotate the trunk. This movement causes compression of the menisci.
Medial compartment pain during internal rotation of the tibia indicates a medial meniscal lesion. Lateral compartment pain occurring during external rotation of the tibia indicates a lateral meniscal lesion.
Modified Helfet test
While the patient is sitting on the edge of a table with the knee flexed 90°, instruct him or her to extend the knee.
If knee mechanics are within normal limits, the tibial tuberosity can be seen in line with the midline of the patella in full flexion; during extension, the tibia rotates and the tibial tubercle moves into line with the lateral border of the patella.
Failure of the tibia to rotate during extension indicates a meniscal lesion or cruciate ligament involvement.
O'Donoghue test
With the patient prone, the examiner flexes the knee 90°. The examiner rotates the tibia internally and externally twice, then fully extends the knee and repeats the rotations.
Increased pain during rotation in either or both knee positions indicates a meniscal tear or joint capsule irritation.
With a valgus force to a flexed and laterally rotated knee, the medial meniscus, medial collateral ligament (MCL), and ACL all may be injured, representing the O'Donoghue triad.
Payr sign
With the patient sitting cross-legged, the examiner exerts downward pressure along the medial aspect of the knee.
Medial knee pain indicates a posterior horn lesion of the medial meniscus.
First Steinmann sign
With the patient supine and the knee and hip flexed at 90°, the examiner forcefully and quickly rotates the tibia internally and externally.
Pain in the lateral compartment with forced internal rotation indicates a lateral meniscal lesion. Medial compartment pain during forced external rotation indicates a lesion of the medial meniscus.
Second Steinmann sign
This test is indicated when point tenderness is located along the anterior joint line.
When the examiner moves the knee from extension into flexion, the meniscus is displaced posteriorly along with its lesions. The point of tenderness also shifts posteriorly toward the collateral ligament.
Thessaly test
This maneuver is performed with the patient standing on one leg and the knee flexed to 5° and 20°, while the patient holds the examiner’s hand for balance. From this position, the patient is asked to internally and externally rotate the knee. Pain or a locking or catching sensation at the medial or lateral joint line is suggestive of meniscal tears.
Causes
Most commonly, meniscal injuries are due to a traumatic event (especially in athletes) or degenerative changes (in older individuals). Meniscal tears are caused by twisting motions with the knee in a flexed position (eg, pivoting in basketball). Chronic or repetitive stress also may cause degenerative tears of the menisci. [9, 21]
A Danish study investigated whether an association exists between meniscal injuries and occupations that require kneeling. [22] MRI of the knees was conducted in 92 male floor layers and compared with MRI scans from referents, in this case 49 male graphic designers. (The mean age for all persons in the study was 55.6 years.) The incidence of degenerative tears of the medial meniscus was significantly higher in floor layers than in graphic designers, the odds ratio (OR) being 2.28. Medial tears in both knees also occurred more frequently in floor layers (OR 3.46). Tears in the lateral meniscus, however, were no more prevalent in floor layers than in graphic designers.
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Magnetic resonance imaging scan showing a normal meniscus.
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Magnetic resonance imaging scan showing a torn medial meniscus.
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Arthroscopic probing of a posterior horn complex meniscal tear with multiple flaps.
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Arthroscopic view of medial meniscus after excision of flap tear.
