Meniscal Tears

Aetiology

  • Younger patients - usually sporting injury
    • Classically twisting force on a loaded knee e.g. turning at football, squatting
  • Older patients (middle age onwards) - can get atraumatic spontaneous degenerate tears
    • Common - 20% over 50, many asymptomatic
    • Meniscus weakens with age and can tear spontaneously or with a seemingly innocuous injury
    • Probably represents 1st stage of knee OA
    • Pain from 2nd effects - bone marrow oedema, synovitis
  • 50% of ACL ruptures have meniscal tear
  • Medial meniscal tears approx. 9-10 times more common than lateral meniscal tears

Clinical presentation

Symptoms

  • Pain and tenderness localised to joint line
    • Medial joint line tenderness = medial meniscus, lateral joint line tenderness = lateral meniscus
  • Patients knees may feel about to give way if a loose meniscal fragment is caught in the knee when walking
  • Catching or locking sensation

Signs

  • May be inflammatory effusion present
  • Positive meniscal provocation tests e.g. Steinman's (unreliable)
  • Acute locked knee signifies displaced bucket handle meniscal tear
    • Large meniscal fragment is able to flip out of its normal position and displace anteriorly or into the intercondylar notch where the knee locks and is unable to fully extend due to mechanical obstruction from the trapped meniscal fragment
    • Patient will have 15° springy block to extension
    • Heel height asymmetry indicating fixed flexion deformity

Investigations

  • MRI

Management

  • The meniscus only has an arterial blood supply in its outer third and therefore has limited healing potential
    • Radial tears won't settle
  • Pain and inflammation from initial injury may settle, especially with degenerative tears

Younger patients

  • Higher proportion of peripheral or bucket handle meniscal tears which may benefit from meniscal repair
  • Consider arthroscopic meniscal repair for acute traumatic peripheral meniscal tears in younger patients
    • Involves suturing the meniscus to its bed
  • Even with careful patient selection around 25% of meniscal repairs fail requiring arthroscopic menisectomy
  • Consider arthroscopic meniscectomy for irreparable tears with recurrent pain, effusion or mechanical symptoms (catching, clicking, locking) which fails to settle within 3 months
  • Knees with degenerate changes on xray (loss of joint space, sclerosis, osteophytes) or MRI (hyaline cartilage loss, bone marrow oedema) are unlikely to benefit from arthroscopic menisectomy as removal of meniscal tissue may increase the stress on already worn / damaged surfaces
  • Young patients have a higher chance of healing with a meniscal repair

Degenerative tears

  • Corticosteriod injection may help with symptoms in the early period
  • Healing potential also decreases with age (over about 25‐30 years of age healing rates are poor) and with increased time from the injury
  • Arthroscopic menisectomy ineffective - only for unstable tear with mechanical symptoms, not for pain only

Bucket handle tears

  • May be repairable if picked up early
  • If knee remains locked, may develop permanent fixed flexion deformity
  • If irreparable needs partial meniscectomy to unlock knee and prevent further damage