Summary

The menisci are C-shaped fibrocartilaginous discs that act as Shock Absorbers and Load Distributors (converting axial load into hoop stress). Meniscal tears are the most common knee injury. They fall into two categories: Acute Traumatic (Young, twisting injury, locking) and Degenerative (Old, horizontal cleavage, minimal trauma). The "Save the Meniscus" philosophy is paramount: a total meniscectomy increases contact stress by 300%, leading to rapid osteoarthritis (Fairbank's changes). Bucket Handle Tears causing locking are urgent surgical targets. Degenerative tears are best managed non-operatively (FIDELITY trial). [1,2,3]

Key Facts

• Vascular Zones:
  • Red-Red (Outer 1/3): Vascular. High healing potential. REPAIR.
  • Red-White (Middle 1/3): Variable. REPAIR if young.
  • White-White (Inner 1/3): Avascular. No healing. RESECT.
• The "Locked Knee": A true mechanical block to extension (usually cannot extend last 10-20 degrees) implies a bucket handle tear has flipped into the notch. This requires urgent arthroscopy to salvage the tissue before it plastically deforms.

Clinical Pearls

"Delay is Decay": A locked bucket handle tear that is left for weeks becomes stiff and deformed ("plastic deformation"), making it irreparable. Time is tissue.

"Degenerative? Don't Operate": If a patient is >45 with a horizontal cleavage tear and no true locking, arthroscopy does NOT improve outcomes compared to placebo (FIDELITY).

"The Ghost Sign": On sagittal MRI, absence of the posterior horn triangle indicates a Root Tear (Avulsion). This is a devastating injury that functions like a total meniscectomy.

1. Inspection

• Look for Quads atrophy (VMO).
• Check extension (Is it locked?).

2. Palpation

• Identify the joint line. Tenderness is key.

3. Special Tests

• Steinmann I / II: Varying pain with flexion/extension (meniscus moves posteriorly in flexion).
• Apley's Grind: Prone compression. Differentiates collateral ligament (Distraction) vs Meniscus (Compression).

MRI (Gold Standard)

• Sensitivity: 95%.
• Criteria: High signal extending to the articular surface.
• Bucket Handle Signs:
  • Double PCL Sign: The fragment sits in front of the PCL.
  • Fragment in Notch: Additional tissue in the intercondylar notch.
• Discoid Meniscus: >3 consecutive sagittal slices showing meniscal body.

X-Ray

• Required to rule out OA.
• Rosenberg View (PA Flexion): Shows "skier's" wear pattern.

                 MENISCAL TEAR DIAGNOSED
                        ↓
             LOCKED KNEE (Bucket Handle)?
            ┌────────────┴─────────────┐
           YES                        NO
            ↓                          ↓
     URGENT ARTHROSCOPY          DEGENERATIVE OR ACUTE?
    (Repair vs Resect)        ┌────────┴────────┐
                          ACUTE/TRAUMATIC    DEGENERATIVE (>45)
                            (Young)             ↓
                               ↓             PHYSIOTHERAPY (3-6m)
                          ARTHROSCOPY           ↓
                          (Repair Goal)      FAIL? -> SCOPE

Indications

• Degenerative tears (Horizontal).
• Age >45 with OA.
• No true locking.
• Small stable tears (<10mm).

Protocol

• RICE: Rest, Ice, Compression, Elevation.
• Physiotherapy: Quads strengthening.
• Evidence: METEOR Trial showed PT is as effective as surgery for degenerative tears.

1. Partial Meniscectomy

• Indication: White-White tears. Complex degenerative tears involved in mechanical locking.
• Technique: Resect only the unstable portion. "Less is More".
• Outcome: Rapid recovery (Back to sport 6 weeks). Higher long-term arthritis risk.

2. Meniscal Repair

• Indication: Red-Red or Red-White tears. Bucket Handle tears. Young patients. Root repairs.
• Techniques:
  • Inside-Out: Gold standard for middle/posterior tears. Need a safety incision.
  • All-Inside: Suture anchors (FastFix) for posterior horn.
  • Outside-In: For anterior horn.
• Rehab: Restricted weight bearing (Touch toe) and ROM (0-90) for 6 weeks to protect the suture. Return to sport 6 months.

3. Meniscal Scaffolds / Transplant

• Indication: Young patient with "Post-Meniscectomy Syndrome" (Pain in compartment).
• Technique: CMI (Collagen Implant) or Allograft.
• Goal: Bridge to arthroplasty.

Repair Protocol (The "Slow Road")

• Weeks 0-2: NWB or TWB in brace locked in extension.
• Weeks 2-6: 0-90 flexion only.
• Months 3-4: Jogging.
• Months 6: Pivoting sports.

Meniscectomy Protocol (The "Fast Road")

• Day 0: Full weight bearing.
• Week 2: Bike.
• Week 4-6: Run.

FIDELITY Trial (2013 NEJM)

• Arthroscopic Partial Meniscectomy vs SHAM surgery for degenerative tears.
• Result: No difference at 12 months.
• Impact: Practice changing. Do not scope degenerative knees just for pain.

METEOR Trial (2013 NEJM)

• APM vs PT for meniscal tear with mild OA.
• Result: No significant difference. 30% of PT group crossed over to surgery, but outcomes were similar.

What is the meniscus?

It is a shock absorber in the knee, like a rubber washer. It protects the coating of the bone (cartilage).

Can it heal?

The outer rim has a blood supply and can heal if stitched. The inner rim has no blood supply and cannot heal—it must be trimmed smooth.

Why not just trim it all out?

If we remove the shock absorber, the forces on your bone increase by 300%. This leads to arthritis very quickly. We try to save it whenever possible.

Recovery time?

If we Trim it: 6 weeks. If we Stitch it: 6 months. The stitch takes longer but saves your knee in the long run.

Q1: What are "Fairbank's Changes"? A: Radiological signs of OA seen after meniscectomy: 1. Joint space narrowing. 2. Osteophyte formation (squaring of condyle). 3. Subchondral sclerosis.

Q2: What is the "Double PCL" sign? A: A specific MRI sign of a displaced Bucket Handle Tear. The displaced fragment lies anterior to the PCL.

Q3: Describe the vascular zones of the meniscus. A: Red-Red (Peripheral 10-25%, vascular). Red-White (Transitional, variable). White-White (Central 50%, avascular).

(End of Topic)