Meniscus Tear: Causes, Symptoms, Diagnosis, and Treatment

What Is the Meniscus?

The knee has two C-shaped wedges of fibrocartilage called menisci — one on the inner (medial) side and one on the outer (lateral) side of the knee. The medial meniscus is larger and crescent-shaped; the lateral meniscus is more circular.

The menisci serve critical functions:

Load sharing and shock absorption: Transmit and distribute 50–70% of compressive knee loads
Joint stability: Deepen the socket of the knee, contributing to stability
Lubrication and nutrition: Distribute synovial fluid across the joint
Proprioception: Contribute to joint position sensing

Removing meniscal tissue (meniscectomy) significantly increases the risk of knee osteoarthritis. This understanding has fundamentally changed treatment philosophy — preserve as much meniscus as possible.

Types of Meniscus Tears

By tear pattern:

Horizontal tear: Splits the meniscus into upper and lower halves; degenerative; treatment typically partial meniscectomy or leave alone
Vertical/longitudinal tear: Along the length of the meniscus; traumatic tears in young patients; repairable in vascular zones
Bucket-handle tear: A complete longitudinal tear that flips into the joint — can cause knee locking
Radial tear: Across the width of the meniscus; disrupts hoop stress function significantly
Complex/degenerative tear: Multiple tear patterns; associated with OA in older patients

By location (vascularity):

Red-red zone (outer 1/3): Well-vascularized; tears here heal with repair
Red-white zone (middle 1/3): Some vascularity; repair possible in select cases
White-white zone (inner 1/3): Avascular; tears here do not heal with repair — partial meniscectomy required

Causes

Traumatic tears: Sudden twisting with the foot planted — common in sports (football, basketball, soccer); often coexist with ACL tears

Degenerative tears: Gradual wear and thinning of the meniscus with age; minimal trauma can cause tearing; very common in patients over 40 with knee OA

Symptoms

Joint line pain: Medial or lateral knee pain along the joint line
Swelling: May develop over 24–48 hours after a traumatic tear; more gradual with degenerative tears
Clicking or popping
Locking: True locking (knee can't be fully extended) is a red flag suggesting a displaced bucket-handle tear requiring urgent treatment
Pain with squatting, kneeling, or stairs
Giving way: From pain inhibition or mechanical instability

Diagnosis

Clinical tests:

McMurray test: Flexion, rotation, and extension — positive if a click or pain at the joint line
Thessaly test: Single-leg squat with knee flexed — reproduces symptoms
Joint line palpation

MRI: The imaging standard for meniscal tears — determines tear type, location (repairable vs. non-repairable zone), extent, and associated pathology.

Treatment

Non-Surgical Management

Degenerative tears in older patients (>35–40): Strong evidence shows that for most degenerative meniscus tears without locked knee, physical therapy produces outcomes equivalent to arthroscopic surgery. PT should be the first-line treatment.

Conservative treatment:

RICE (Rest, Ice, Compression, Elevation) acutely
NSAIDs
Physical therapy: quadriceps strengthening, hamstring flexibility, proprioception training
Corticosteroid or PRP injection

Surgical Treatment

Arthroscopic partial meniscectomy: Removes only the torn, unstable portion of the meniscus. Outpatient procedure; fast recovery (2–6 weeks). Appropriate for:

Mechanical symptoms (locking, catching)
Failed conservative treatment
Young patients with tears unlikely to heal

Arthroscopic meniscal repair: Sutures the torn meniscus back together. Reserved for:

Young patients (<40)
Peripheral (red-red zone) tears with healing potential
Acute traumatic tears (especially with concurrent ACL tear)
Larger tear patterns

Recovery from repair is much longer (3–6 months vs. 2–6 weeks) but preserves the meniscus and reduces long-term OA risk.