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BASICS

DESCRIPTION
The menisci are fibrocartilaginous structures located between the femoral condyles and the tibial plateaus.
They help to stabilize the knee (with the ACL) and distribute forces across the joint for shock absorption.
Meniscal tears cause knee pain and disability and are a risk factor for knee osteoarthritis (OA).

Pediatric Considerations
- Meniscal injuries are less common in children <10 years, often due to discoid meniscus.
- MRI is the preferred study but less sensitive/specific in children <12 years.
- Increased BMI in pediatrics correlates with more complex tears and lower repair success.

EPIDEMIOLOGY

  • Bimodal age distribution: young athletes (traumatic) and older patients (degenerative).
  • Medial meniscus is more commonly injured.
  • Meniscal surgery is the most common orthopedic surgery in the US.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Traumatic tears: acute, due to twisting with foot planted; common in <40 years without OA; sudden pain.
  • Degenerative tears: chronic, overuse with minimal trauma; increase with age; often comorbid with OA; symptoms evolve slowly.

Genetics: No specific gene locus identified.

RISK FACTORS

Nonmodifiable: male sex, discoid meniscus, ligamentous laxity
Traumatic tears: high physical activity (cutting sports), ACL insufficiency
Degenerative tears: age >60, obesity, kneeling/squatting/climbing stairs at work

GENERAL PREVENTION

  • Rehabilitation of prior injuries, especially ACL injuries.
  • Strengthen and increase flexibility of quadriceps and hamstrings.
  • Weight management.

COMMONLY ASSOCIATED CONDITIONS

  • Traumatic tears: 1/3 have concomitant ACL tear.
  • Degenerative tears: associated with OA and Baker cysts.

DIAGNOSIS

HISTORY
- Medial/lateral knee pain and swelling, worsened with knee flexion.
- Noncontact twisting injury if trauma.
- ± Mechanical symptoms (locking, catching).
- Young patients: often entrapped meniscal tissue post-trauma; older patients: degenerative or OA.

PHYSICAL EXAM
- Effusion >24 hours post injury.
- Joint line tenderness (medial/lateral).
- Decreased range of motion; pain on full flexion (posterior horn) or extension (anterior horn).
- Special tests (McMurray, Apley) have variable accuracy.

DIFFERENTIAL DIAGNOSIS

  • ACL or collateral ligament tear
  • Pathologic plica
  • Osteochondritis dissecans
  • Loose body or fracture
  • Osteoarthritis
  • Patellofemoral syndrome

DIAGNOSTIC TESTS & INTERPRETATION

  • Plain radiographs to rule out fractures, loose bodies, arthritis.
  • Ultrasound may identify tears.
  • MRI is the primary imaging for meniscal tears.
  • Arthroscopy if MRI indeterminate.
  • Correlate imaging with clinical exam; incidental asymptomatic tears are common in middle-aged/older patients with OA.

TREATMENT

GENERAL MEASURES
- Nonoperative management first-line for most tears:
- Rest, ice, activity modification
- OTC medications
- Physical therapy (PT)
- Intra-articular corticosteroids
- No added benefit of surgery over PT in patients >40 years with degenerative tears【1】.
- Early surgery may not always be superior in young active patients.

MEDICATION
- NSAIDs (ibuprofen up to 800 mg TID, naproxen 500 mg BID) or acetaminophen.
- Corticosteroid injections (lidocaine + methylprednisolone acetate).

ISSUES FOR REFERRAL

  • Surgical consult if no improvement with PT or patient desires surgery.

ADDITIONAL THERAPIES

  • Weight control.
  • Platelet-rich plasma (PRP) injections may help symptoms from degenerative tears.

SURGERY/OTHER PROCEDURES

Consider surgery if:
- Concurrent ACL injury
- Mechanical symptoms (catching/locking)
- Failure of conservative treatment
- Early surgery best for mechanical symptoms in <40 years【2】.
- Meniscal preservation (repair/replacement) preferred in older patients, better outcomes vs. meniscectomy【3】.
- Meniscectomy increases risk of OA.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS
- Return to play only when pain-free, full range of motion, and full strength.

PATIENT EDUCATION

  • Discuss risks and benefits of surgery vs conservative management.

PROGNOSIS

  • Return to activities 3 to 6 months after repair.
  • Better prognosis if tear is peripheral/lateral and <2.5 cm.

COMPLICATIONS

  • Meniscectomy increases risk of developing osteoarthritis.

REFERENCES

  1. Rotini M, Papalia G, Setaro N, et al. Arthroscopic surgery or exercise therapy for degenerative meniscal lesions: a systematic review of systematic reviews. Musculoskel Surg. 2023;107(2):127-141.
  2. Damsted C, Thorlund JB, Hölmich P, et al. Effect of exercise therapy versus surgery on mechanical symptoms in young patients with a meniscal tear: a secondary analysis of the DREAM trial. Br J Sports Med. 2023;57(9):521-527.
  3. Husen M, Kennedy NI, Till S, et al. Benefits of meniscal repair in selected patients aged 60 years and older. Orthop J Sports Med. 2022;10(9).

ICD10 Codes

  • S83.209A Unspecified tear of unspecified meniscus, current injury, unspecified knee, initial encounter
  • S83.249A Other tear of medial meniscus, current injury, unspecified knee, initial encounter
  • S83.289A Other tear of lateral meniscus, current injury, unspecified knee, initial encounter

Clinical Pearls

  • Chronic/degenerative meniscal tears common in patients >40 years and associated with knee OA.
  • Acute/traumatic tears common in young athletes.
  • Conservative management (PT/education) preferred first-line with option for later surgery.
  • MRI is imaging modality of choice.
  • Meniscal repairs have better functional outcomes and lower OA risk compared to meniscectomy.