- Knee Meniscus Tear is among the most common sport injury seen by orthopedic surgery.
- The medial meniscus is torn approximately three times more often than the lateral meniscus.
- Lateral meniscus tears occur more commonly with concomitant ACL tear
- Traumatic meniscus tears are common in young patients with sports-related injuries.
- While degenerative meniscus tears usually occur in older patients.
- Meniscus anatomy has been discussed previously.
Mechanism of the meniscus tear
- Meniscus Tear usually occurs by a rotational force incurred while the joint is partially flexed.
Classification based on the location of the meniscus tear:
- The tear may occurs at:
- Red-Red zone
- Red-White zone.
- White-White zone.
- It’s also classified as it may occur at:
- Posterior third of the meniscus (Posterior horn)
- Middle third of the meniscus.
- Anterior third of the meniscus (Anterior horn).
Classification based on the shape (Pattern) of the meniscus tear:
|Type of tear||Characteristics|
|Vertical longitudinal||– The most Common (especially in the setting of ACL tears).|
– It can be repaired if located in the peripheral third of the meniscus.
|Bucket-handle||– A vertical longitudinal tear displaced into the notch.|
– Double PCL sign.
|Radial||– Starts centrally and proceeds peripherally.|
– It’s not repairable because of loss of circumferential fiber integrity.
|Flap||– Begins as a radial tear and proceeds circumferentially.|
– May cause mechanical locking symptoms.
|Horizontal cleavage||– Occurs more frequently in the older population.|
– May be associated with meniscal cysts.
|Complex||– A combination of tear types.|
– More common in the older population.
Symptoms and signs:
- localized Pain and tenderness at the medial or lateral side of the knee (based on the injured meniscus).
- The meniscus itself is without nerve fibers except at its periphery; therefore, the tenderness or pain is related to synovitis in the adjacent capsular and synovial tissues.
- Locking of the knee: it is usually occurs only with longitudinal tears and is much more common with bucket-handle tears, usually of the medial meniscus.
- A sensation of “giving way” or snaps, clicks, catches, or jerks in the knee may be described by the patient.
- Swelling (Effusion) of the knee due to hemarthrosis that can occur when the vascularized periphery of a meniscus is torn (The absence of an effusion or hemarthrosis does not rule out a tear of the meniscus).
- Atrophy of the musculature around the knee, especially of the vastus medialis muscle (suggests a recurring disability of the knee).
- Recommended views:
- Anteroposterior, lateral, and intercondylar notch views with a tangential view of the inferior surface of the patella.
- They are essential to exclude osteo-cartilaginous loose bodies, osteochondritis dissecans, and other pathological processes that can mimic a torn meniscus.
- It’s a noninvasive procedures.
- MRI has been shown to have 98% accuracy for medial meniscal tears and 90% for lateral meniscal tears.
Treatment of torn Meniscus
- An incomplete meniscal tear or a small (5 mm) stable peripheral tear with no other pathological condition, such as a torn anterior cruciate ligament.
- Tears associated with ligamentous instabilities can be treated nonoperatively if the patient defers ligament reconstruction or if reconstruction is contraindicated.
- Removal of the menisci, especially the medial meniscus, in such knees may make the instability even more severe.
- Meniscus tears in the absence of intermittent swelling, catching, locking, or giving way.
- Knee immobilizer worn for 4 to 6 weeks (groin-to-ankle cylinder cast).
- Progressive isometric exercise program during the time the leg is in the cast to strengthen the muscles around the knee.
- At 4 to 6 weeks, the immobilization is discontinued and the rehabilitative exercise program for the muscles around the hip and knee is intensified.
- Tears that are not amenable to repair (e.g., peripheral, longitudinal tears).
- Complex, degenerative, and central/radial tears are treated with resection of a minimal amount of normal meniscus.
- Tear size between 1 cm and 4 cm.
- Vertical tear.
- Tears in the Red-Red zone.
- Meniscal root tear.
- Age younger than 40 years.
- There are 4 techniques used to repair a torn meniscus:
- Open Surgical repair:
- It’s uncommon technique except in trauma (knee dislocations).
- Inside-out technique.
- Outside-in technique.
- All-inside technique.
- Open Surgical repair:
- There also Meniscal Transplantation.
Complications of treatment:
- Saphenous neuropathy .
- Sterile effusion.
- Peroneal neuropathy.
- Superficial infection.
- Deep infection.