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Meniscus Discoid M23.009 717.5

discoid lateral meniscus 


ICD-9 Classification / Treatment
Etiology / Natural History Associated Injuries / Differential Diagnosis
Anatomy Complications
Clinical Evaluation Follow-up Care
Xray / Diagnositc Tests Review References

synonyms: "Popping knee syndrome," discoid meniscus

Discoid Meniscus ICD-10

Discoid Meniscus ICD-9

  • 717.5 (derangement of meniscus, not elsewhere classified)

Discoid Meniscus Etiology / Epidemiology / Natural History

  • Discoid menisus is a congenital abnormality caused by failure of apoptosis during development in utero.  No known genetic cause.
  • Prone to tearing and often with minimal trauma. 
  • Contralateral discoid menisci are noted in 20% of patients. 

Discoid Meniscus Anatomy

Discoid Meniscus Clinical Evaluation

  • C/O knee pain with mechnical symptoms.
  • Meniscal symptoms in a child <10y/o.
  • Classic complaint is popping with the knee in extension.

Discoid Meniscus Xray / Diagnositc Tests

  • Lateral and weight bearing A/P knee films, may show joint space widening, squaring of the lateral condlye, cupping of the lateral tibia plateau or a hypoplastic lateral intercondylar spine.
  • MRI: generally clearly shows abnormal meniscal morphology.

Discoid Meniscus Classification / Treatment

  • Incomplete (Type II):
  • Complete (Type I):
  • Wrisberg's variant Type III): discoid meniscus is only attached to the medial femoral condyle via the meniscofemoral (Wrisberg) ligament. Can displace into the notch with knee extension.
  • Incidental discoid meniscus found during knee arthroscopy do not require treatment
  • Tears in discoid menisci are treated with excision of the torn portion and saucerization. Repair is indicated for peripheral detachments.

Discoid Meniscus Associated Injuries / Differential Diagnosis

Discoid Meniscus Complications

Discoid Meniscus Follow-up Care

  • 71% excellent, 24% good, 5% fair for arthroscopic lateral menisectomy in patients with symptomatic discoid lateral meniscus. (Aglietti P, Am J Knee Surg 1999;12:83).

Discoid Meniscus Review References


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