Meniscus Injury

Aka: Meniscus Injury, Meniscus Tear, Meniscal Injury, Lateral Meniscal Tear, Medial Meniscal Tear, Lateral Meniscus Tear, Medial Meniscus Tear, Locked Knee Syndrome, Knee Locking, Meniscus Bucket Handle Tear

1. Epidemiology
   1. Most common Knee Injury
2. Anatomy: Menisci
   1. Meniscus cushions forces between femur and tibia
   2. Fibrocartilaginous C-shaped (semilunar) objects
      1. Medial meniscus (90%)
         1. Less mobile than lateral meniscus
      2. Lateral meniscus (10%)
3. Mechanism: Twisting injury
   1. Fixed tibial rotation with knee flexion or extension
4. Associated injuries
   1. Anterior Cruciate Ligament Tear (33% of cases)
5. Symptoms
   1. Twisting injury to knee while weight bearing
   2. Initial tearing, painful Sensation felt
   3. Pain localized to affected meniscus
   4. Buckling Sensation
   5. Gradual onset of effusion following injury
   6. Provocative
      1. Stair climbing or stair descent
      2. Squatting
   7. Knee Locking
      1. Intermittent Locking (common)
      2. Locked Knee Syndrome (uncommon)
         1. May result in persistent inability to flex and extend knee
         2. Meniscus Bucket Handle Tear refers to torn meniscus fragment that flips into intercondylar notch
            1. Prevents knee range of motion, and results in difficult ambulation
         3. May be associated with Anterior Cruciate Ligament Tear
         4. Indicates early MRI and orthopedic Consultation
6. Signs
   1. Joint effusion
   2. McMurray's Test positive
   3. Apley's Compression Test positive
   4. Apley's Distraction Test negative
   5. Knee Bounce Test positive
7. Imaging
   1. Knee XRay
      1. Initial Knee Injury evaluation for Fracture
   2. Knee MRI
      1. Diagnosis of meniscal tear
8. Management: Conservative
   1. RICE-M
   2. NSAIDs
   3. Crutch walking
   4. Physical therapy
      1. Gentle knee range of motion Exercises after 2-3 days
         1. Consider Swimming
      2. Quadriceps strengthening Exercises for 2-4 weeks
         1. Initially perform with knee extended
      3. Active rehabilitation is as effective as arthroscopy for pain and function in degenerative tears
         1. Herrlin (2007) Knee Surg Sports Traumatol Arthrosc 15(4): 393-401 +PMID:17216272 [PubMed]
9. Management: Arthroscopy
   1. Indications
      1. Irreducible locking (see Locked Knee Syndrome above)
      2. Mechanical symptoms (locking or catching)
      3. Refractory meniscus symptoms (e.g. pain) despite above management
   2. Efficacy arthroscopy, meniscectomy and Debridement
      1. No longterm benefit in middle aged and older patients (with or without Knee DJD)
      2. No significant improvement in knee catching or locking in those with meniscal tear
      3. Exercise therapy is preferred
      4. Sihvonen (2016) Ann Intern Med 164(7): 449-55 [PubMed]
      5. Thorlund (2015) BMJ 350:h2747 [PubMed]
      6. Khan (2014) CMAJ 186(14):1057-64 [PubMed]
10. Prognosis: Predictors of Best Longterm Outcomes
    1. Acute, non-degenerative meniscal tear
    2. Age <35 years old
    3. Vertical meniscal tear
    4. No cartilage injury
    5. Intact meniscal rim after meniscectomy
11. Complications
    1. Knee Osteoarthritis
12. References
    1. Mercier (1995) Practical Orthopedics, Mosby, p. 217-9
    2. Rashidzada (2020) Crit Dec Emerg Med 34(9): 16-7
    3. Smith (1995) Am Fam Physician 51(4): 799-806 [PubMed]