Meniscus Tears

International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS)

Most comprehensive and widely accepted classification:

Click to expand

Click to expand

ISAKOS also describes:

• Location: Anterior horn, body, posterior horn
• Depth: Partial (superior or inferior surface) vs full-thickness
• Length: Measured in mm
• Quality: Traumatic (good tissue) vs degenerative (poor tissue)

Bucket-Handle Tears - Special Category

Definition: Complete vertical longitudinal tear with displacement of inner fragment into intercondylar notch.

Clinical presentation:

• Mechanical symptoms: Locking, catching, inability to fully extend
• Extension deficit: 10-30 degrees of lost extension
• Joint line tenderness
• Positive McMurray test

Surgical management:

• Repair is strongly preferred if tissue quality allows
• Typically involves 3-5 vertical mattress sutures
• Inside-out technique for posterior horn
• May need ACL reconstruction if associated (40% have ACL tears)

Outcomes:

• Repair success: 80-85% if peripheral (under 3mm from rim)
• Significantly better long-term than resection
• Return to sport: 6-9 months after repair

These results emphasize the importance of attempting repair for displaced bucket-handle tears.

Meniscal Root Tears - Critical Subtype

Definition: Complete radial tear or avulsion at the meniscal root attachment to tibia.

Location:

• Posterior medial root (most common) - 80% of root tears
• Posterior lateral root
• Anterior roots (rare)

Biomechanical impact:

• Complete loss of hoop stress function
• Functionally equivalent to total meniscectomy
• Rapid progression to OA (14 times higher risk)
• Meniscus extrusion on MRI (more than 3mm)

Surgical technique (Transtibial Pullout):

1. Arthroscopic identification of root tear
2. Tibial bone tunnel at anatomic root insertion
3. Sutures passed through meniscal root tissue
4. Sutures pulled through tunnel and tied over bridge or button
5. Restores hoop stress mechanism

Discoid Meniscus - Developmental Variant

Definition: Abnormally thick, disc-shaped lateral meniscus (rarely medial).

Watanabe classification:

• Type I (Complete): Meniscus covers entire lateral plateau
• Type II (Incomplete): Partial coverage but wider than normal
• Type III (Wrisberg variant): No posterior meniscotibial ligament attachment

Presentation:

• Snapping knee syndrome in children (Wrisberg type)
• Lateral knee pain
• Joint line tenderness
• Often asymptomatic until tear occurs

Management:

• Asymptomatic: Observe (don't operate just because it's discoid)
• Symptomatic tear: Arthroscopic saucerization + tear repair
• Goal: Create normal C-shaped meniscus, preserve peripheral rim

The key principle is preserving tissue while creating a stable, functional meniscus.

Non-Operative Treatment

Indications:

• Degenerative tears in patients over 45 years (MenTOR trial)
• Small stable tears without mechanical symptoms
• Grade I-II MRI signal (intrasubstance degeneration)
• Patient choice or medical comorbidities

When to Operate

Clear surgical indications:

• Locked knee from bucket-handle tear (urgent)
• Significant mechanical symptoms (catching, locking) despite conservative treatment
• Young patient with traumatic tear (attempt repair)
• Root tear with meniscus extrusion (restore hoop stress)
• Repairable tear in vascular zone (preserve meniscus)

Consider conservative first:

• Degenerative tear in patient over 45
• Small stable tear without mechanical symptoms
• Patient with advanced OA (surgery won't help)

Arthroscopic Meniscus Repair

Repair techniques:

1. Inside-out sutures:

   • Gold standard for posterior horn and body
   • Requires accessory posteromedial or posterolateral incision
   • Direct visualization of neurovascular structures
   • Best fixation strength
   • Risk: Saphenous nerve (medial), peroneal nerve (lateral)

2. Outside-in sutures:

   • Good for anterior horn and anterior body
   • Sutures passed from skin to joint, then back out
   • Less commonly used

3. All-inside devices:

   • Various implants (arrows, darts, suture anchors)
   • No accessory incision
   • Faster, technically easier
   • Risk: Neurovascular injury if device penetrates too far
   • Similar outcomes to inside-out

Surgical steps:

1. Arthroscopic examination and tear assessment
2. Debride tear edges (remove unstable flaps, roughen surfaces)
3. Create vascular access channels (trephination, rasping) to promote healing
4. Pass sutures (vertical mattress pattern, 3-5mm apart)
5. Tie sutures with knee at 20 degrees flexion
6. Confirm stable repair on probing

Augmentation techniques:

• Fibrin clot: Place in repair site (improved healing in red-white zone)
• PRP injection: Platelet-rich plasma (controversial benefit)
• Marrow venting: Create bone marrow channels from tibia to enhance vascular response

These adjuncts may improve healing rates, especially in red-white zone repairs.

Meniscal Root Repair Technique

Transtibial pullout technique (Gold standard):

Outcomes:

• Root repair success: 70-85%
• Significant reduction in meniscus extrusion
• Slows progression of OA
• Best results when performed within 6 months of injury

Early repair provides the best chance for functional restoration and OA prevention.

When Meniscectomy is Necessary

Indications for partial meniscectomy:

• Irreparable tear (central location, degenerative tissue)
• Failed repair
• Unstable flap tear causing mechanical symptoms
• Complex tear with poor healing potential

Principles:

• Preserve as much meniscus as possible
• Create smooth, stable rim
• Remove only unstable, damaged tissue
• Never perform total meniscectomy (increases OA risk dramatically)

Positioning and Portal Placement

Patient position:

• Supine on operating table
• Leg holder or post at 90 degrees of knee flexion
• Tourniquet applied (usually not inflated for arthroscopy)
• Non-sterile drape to allow knee flexion

Portal placement:

Arthroscope insertion:

• Make skin incision with #11 blade
• Insert blunt trocar through capsule
• Insert arthroscope
• Perform systematic examination: suprapatellar pouch, medial and lateral gutters, patellofemoral joint, medial and lateral compartments, notch, posterior horns

A systematic examination identifies all pathology before proceeding with treatment.

Partial Meniscectomy Technique

Technique pearls:

• Use "rim-sparing" technique - preserve every millimeter of stable meniscus
• For posterior horn tears: use 70-degree arthroscope for better visualization
• For radial tears: smooth edges but accept that some defect remains
• For horizontal tears: remove inferior leaf if unstable, preserve superior if stable

Nerve injuries (most significant risk with inside-out technique):

• Medial meniscus repair:

  • Saphenous nerve injury: 2-5% incidence
  • Presents as numbness/paresthesia over posteromedial leg
  • Prevention: Use retractor to protect neurovascular structures, make safe accessory incision
  • Usually resolves over 6-12 months

• Lateral meniscus repair:

  • Peroneal nerve injury: Less than 1% (more serious)
  • Risk of foot drop if nerve damaged
  • Prevention: Keep knee flexed 90 degrees, use lateral safety incision
  • May require nerve exploration if complete injury

Repair failure: 10-20% depending on location and technique

• Red-red zone: 10-15% failure
• Red-white zone: 20-30% failure
• Risk factors: White-white location, poor tissue quality, non-compliance with rehab

Other complications:

• Persistent pain: 5-10%
• Stiffness: 5% (usually responds to PT)
• Postoperative meniscal cyst: Rare

Proper technique minimizes nerve injury risk while achieving optimal repair strength.

Immediate complications (similar to repair):

• Infection: Less than 1%
• DVT/PE: 0.1-0.5%
• Hemarthrosis: 5-10% (usually resolves)

Residual symptoms (10-20%):

• May indicate incomplete resection
• May indicate other pathology (chondral damage, ligament injury)
• Consider MRI if symptoms persist beyond 3 months

Long-term complications:

• Accelerated osteoarthritis: 14 times higher risk compared to normal knee
• Progressive joint space narrowing
• Increased pain and functional limitation
• Higher rate of progression to TKA (15-20% at 20 years)

Prevention strategy:

• Preserve every possible millimeter
• Attempt repair in red-red and red-white zones
• Counsel patients about long-term OA risk
• Consider meniscal transplant in young patients with previous total meniscectomy

Understanding the OA risk is essential for shared decision-making with patients.

Infection (less than 1%):

• Usually superficial
• Treatment: Oral antibiotics for superficial, arthroscopic washout for deep
• Prevention: Prophylactic cefazolin 2g IV pre-op

Thromboembolic events (0.1-0.5%):

• DVT rare due to early mobilization
• Routine thromboprophylaxis not indicated for isolated meniscus surgery
• Consider in high-risk patients (obesity, thrombophilia, prolonged immobilization)

Anesthesia complications:

• Regional anesthesia preferred (nerve block, spinal)
• Reduces opioid requirements
• Allows same-day discharge

Portal site complications:

• Numbness from infrapatellar branch of saphenous nerve (common, usually resolves)
• Scar sensitivity
• Keloid formation (rare)

These general complications are similar across all arthroscopic procedures with low overall rates.

Partial Meniscectomy Rehabilitation

Return to sport:

• Desk work: 1-2 weeks
• Manual labor: 4-6 weeks
• Non-contact sports: 6-8 weeks
• Contact sports: 8-12 weeks

Meniscectomy allows rapid return but with long-term OA risk trade-off.

Meniscus Repair Rehabilitation

More restrictive protocol to protect repair:

Root Repair Rehabilitation

Most restrictive protocol (restoring hoop stress):

• Week 0-4: Non-weight-bearing, brace locked in extension
• Week 4-6: Partial weight-bearing (25-50%), ROM to 90 degrees
• Week 6-8: Progress to full weight-bearing, ROM to full
• Week 8-12: Begin strengthening, closed-chain only
• Month 3-6: Progressive functional training
• Month 6+: Return to sport if cleared

Root repair requires longest protection because restoring circumferential hoop stress takes time.