eMedicine Specialties > Orthopedic Surgery > Knee

Discoid Meniscus

Author: Ralph DiLibero, MD, Acting Chief, Policy Section, California Medi-Cal
Contributor Information and Disclosures

Updated: Jun 5, 2009

Introduction

Discoid lateral menisci were first described in the late 1800s. The normal configuration of a meniscus is that of a matured crescent moon, whereas that of a discoid meniscus generally is a thickened, very early crescent moon. Variations of this general shape occur relatively rarely, and occasionally, the lunar appearance is also found in the medial meniscus.

Radiograph of an 8-year-old child with bilateral ...

Radiograph of an 8-year-old child with bilateral discoid menisci, diagnosis confirmed by MRI. Patient is only symptomatic on the left side. Patient underwent arthroscopy and partial meniscectomy and is now asymptomatic. Image courtesy of Dennis P. Grogan, MD.

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Radiograph of an 8-year-old child with bilateral ...

Radiograph of an 8-year-old child with bilateral discoid menisci, diagnosis confirmed by MRI. Patient is only symptomatic on the left side. Patient underwent arthroscopy and partial meniscectomy and is now asymptomatic. Image courtesy of Dennis P. Grogan, MD.



Arthroscopic appearance of a complete discoid lat...

Arthroscopic appearance of a complete discoid lateral meniscus. The probe is showing the medial extent of the lateral meniscus, which completely covers the lateral tibial plateau. Image courtesy of Robert D. Bronstein, MD.

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Arthroscopic appearance of a complete discoid lat...

Arthroscopic appearance of a complete discoid lateral meniscus. The probe is showing the medial extent of the lateral meniscus, which completely covers the lateral tibial plateau. Image courtesy of Robert D. Bronstein, MD.



The discoid shape results in a membrane barrier that prevents normal contact between the articular surfaces of the knee and has a high incidence of mechanical deformation.

Problem

One element in the differential diagnosis of knee pathology is a discoid meniscus. Discoid meniscus can manifest itself as an abnormal band, medial and lateral in the same knee, bilateral and medial, or, more commonly, a discoid lateral meniscus.1,2,3

Frequency

Discoid lateral menisci have been reported to occur at the rate of 1.5-3% in the general population, whereas discoid medial menisci have been reported to occur at the rate of 0.1-0.3%.4 The Asian population has a slightly higher rate of occurrence; Tokyo's Teishin Hospital reported 16.6% of all knees examined arthroscopically had a discoid lateral meniscus.5

Etiology

A discoid lateral meniscus results from a developmental anomaly before birth.6 After birth, no sudden change occurs in meniscal development.7

Pathophysiology

Two distinct types of discoid lateral meniscus exist. One is the hypermobile, or Wrisberg, lateral meniscus, and the other is a misshapen or discoid form of an otherwise normal lateral meniscus. Both types present unique pathophysiologic problems.

The Wrisberg type lacks an attachment to stabilize the posterior horn to the tibia.8 It may also be of normal shape rather than discoid. The only attachment of the posterior horn is to the Wrisberg or meniscofemoral ligament. The general configuration produces an unstable or hypermobile lateral meniscus.

Presentation

Patients present with any combination of pain, giving way, effusion, and clicking or snapping knee.9

Children with discoid meniscus usually present with a snapping knee joint, especially those around 7 years old. The snap can be seen and heard. Translation of the femoral condyle over a thickened posterior rim of lateral meniscus occurs. If the child remains otherwise asymptomatic, only observation is necessary; however, snapping greatly increases the chance of tearing the lateral meniscus, either by continued microtrauma or by trauma that would not cause tearing otherwise.10,11


In a retrospective study of 40 children with symptomatic lateral discoid meniscus, mini-arthrotomy and arthroscopy were compared. Mini-arthrotomy was found to provide slightly better results than arthroscopic resection regarding functional outcome. The authors recommended mini-arthrotomy for the resection of lateral discoid meniscus particularly in young children with narrow joint spaces and for surgeons who are not familiar with arthroscopy in small joints.12

Indications

Abnormalities of knee function, pain, and effusion are indications for surgical treatment.

Relevant Anatomy

Arthroscopic removal of a torn, normally configured lateral meniscus, in its entirety, is accomplished by first releasing the anterior horn, then releasing the attachment to the popliteal tendon, and then partially releasing the posterior horn. Finally, the meniscus is displaced into the intercondylar notch to complete the posterior release and remove the entire meniscus.13

A discoid lateral meniscus often has a continuous attachment from the popliteal tendon to the posterior horn. Removal of the anterior horn is necessary; the remainder of the discoid meniscus is then removed in a piecemeal fashion. An arthroscopic Bovie or other type of coagulation system should be available to stop possible bleeding from a branch of the lateral geniculate artery.

Contraindications

An otherwise asymptomatic knee with the incidental finding of discoid meniscus is a contraindication for surgical treatment.

More on Discoid Meniscus

Overview: Discoid Meniscus
Workup: Discoid Meniscus
Treatment: Discoid Meniscus
Multimedia: Discoid Meniscus
References
Further Reading
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References

  1. Lee BI, Min KD. Abnormal band of the lateral meniscus of the knee. Arthroscopy. Sep 2000;16(6):11. [Medline].

  2. Choi NH, Kim NM, Kim HJ. Medial and lateral discoid meniscus in the same knee. Arthroscopy. Feb 2001;17(2):E9. [Medline].

  3. Akgun I, Heybeli N, Bagatur E, et al. Bilateral discoid medial menisci: an adult patient with symmetrical radial tears in both knees. Arthroscopy. Jul-Aug 1998;14(5):512-7. [Medline].

  4. Ryu KN, Kim IS, Kim EJ, et al. MR imaging of tears of discoid lateral menisci. AJR Am J Roentgenol. Oct 1998;171(4):963-7. [Medline].

  5. Ikeuchi H. Arthroscopic treatment of the discoid lateral meniscus. Technique and long-term results. Clin Orthop. Jul 1982;(167):19-28. [Medline].

  6. Klingele KE, Kocher MS, Hresko MT. Discoid lateral meniscus: prevalence of peripheral rim instability. J Pediatr Orthop. Jan-Feb 2004;24(1):79-82. [Medline].

  7. Clark CR, Ogden JA. Development of the menisci of the human knee joint. Morphological changes and their potential role in childhood meniscal injury. J Bone Joint Surg Am. Apr 1983;65(4):538-47. [Medline].

  8. Kim EY, Choi SH, Ahn JH, Kwon JW. Atypically thick and high location of the Wrisberg ligament in patients with a complete lateral discoid meniscus. Skeletal Radiol. Sep 2008;37(9):827-33. [Medline].

  9. Fung DA, Frey S, Markbreiter L. Bilateral symptomatic snapping biceps femoris tendon due to fibular exostosis. J Knee Surg. Jan 2008;21(1):55-7. [Medline].

  10. Yoo WJ, Choi IH, Chung CY, Lee MC, Cho TJ, Park MS, et al. Discoid lateral meniscus in children: limited knee extension and meniscal instability in the posterior segment. J Pediatr Orthop. Jul-Aug 2008;28(5):544-8. [Medline].

  11. Hart ES, Kalra KP, Grottkau BE, Albright M, Shannon EG. Discoid lateral meniscus in children. Orthop Nurs. May-Jun 2008;27(3):174-9; quiz 180-1. [Medline].

  12. Krause FG, Haupt U, Ziebarth K, Slongo T. Mini-arthrotomy for lateral discoid menisci in children. J Pediatr Orthop. Mar 2009;29(2):130-6. [Medline].

  13. Yukawa T, Ochi M, Kobayashi T, Adachi N, Nakamura M, Yamada K. Magnetic force-assisted meniscal resection under arthroscopy. Knee Surg Sports Traumatol Arthrosc. Oct 2008;16(10):916-20. [Medline].

  14. Araki Y, Ashikaga R, Fujii K, et al. MR imaging of meniscal tears with discoid lateral meniscus. Eur J Radiol. May 1998;27(2):153-60. [Medline].

  15. Connolly B, Babyn PS, Wright JG, et al. Discoid meniscus in children: magnetic resonance imaging characteristics. Can Assoc Radiol J. Oct 1996;47(5):347-54. [Medline].

  16. Andrisani, Miller, Rubenstein. Surgical Management of Discoid Meniscus. Techniques in Knee Surgery. 2006;128-33.

  17. Good CR, Green DW, Griffith MH, Valen AW, Widmann RF, Rodeo SA. Arthroscopic treatment of symptomatic discoid meniscus in children: classification, technique, and results. Arthroscopy. Feb 2007;23(2):157-63. [Medline].

  18. Smith CF, Van Dyk GE, Jurgutis J, Vangsness CT Jr. Cautious surgery for discoid menisci. Am J Knee Surg. Winter 1999;12(1):25-8. [Medline].

  19. Ogata K. Arthroscopic technique: two-piece excision of discoid meniscus. Arthroscopy. Oct 1997;13(5):666-70. [Medline].

  20. Ahn JH, Lee SH, Yoo JC, Lee YS, Ha HC. Arthroscopic partial meniscectomy with repair of the peripheral tear for symptomatic discoid lateral meniscus in children: results of minimum 2 years of follow-up. Arthroscopy. Aug 2008;24(8):888-98. [Medline].

  21. Adachi N, Ochi M, Uchio Y. Torn discoid lateral meniscus treated using partial central meniscectomy and suture of the peripheral tear. Arthroscopy. May 2004;20(5):536-42. [Medline].

  22. Monllau JC, Leon A, Cugat R, Ballester J. Ring-shaped lateral meniscus. Arthroscopy. Jul-Aug 1998;14(5):502-4. [Medline].

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Keywords

discoid meniscus, meniscus injuries, discoid lateral meniscus, discoid lateral menisci, hypermobile meniscus, hypermobile menisci, Wrisberg lateral meniscus, Wrisberg lateral menisci, knee pathology, misshapen lateral meniscus, misshapen lateral menisci, deformed lateral meniscus, deformed lateral menisci, kneecap deformity, knee cap deformity, deformed kneecap, deformed knee cap, kneecap pathology, knee cap pathology, knee arthroscopy, arthroscopic knee surgery

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Contributor Information and Disclosures

Author

Ralph DiLibero, MD, Acting Chief, Policy Section, California Medi-Cal
Ralph DiLibero, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, California Orthopedic Association, and Los Angeles County Medical Association
Disclosure: Nothing to disclose.

Medical Editor

Phillip J Marone, MD, MSPH, Clinical Professor, Department of Orthopedic Surgery, Jefferson Medical College
Phillip J Marone, MD, MSPH is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American College of Surgeons, American Medical Association, American Orthopaedic Society for Sports Medicine, and Philadelphia County Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Thomas M DeBerardino, MD, Associate Professor of Orthopaedic Surgery, University of Connecticut Health Center
Thomas M DeBerardino, MD is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Orthopaedic Association, and American Orthopaedic Society for Sports Medicine
Disclosure: Arthrex, Inc. Grant/research funds Other; Arthrex, Inc. Honoraria Speaking and teaching; Genzyme Biosurgery. Inc. Grant/research funds Other; Musculoskeletal Transplant Foundation Grant/research funds Other; Histogenics Grant/research funds None; Arthrex, Inc. Consulting fee Speaking and teaching

CME Editor

Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital
Dinesh Patel, MD, FACS is a member of the following medical societies: American Academy of Orthopaedic Surgeons
Disclosure: Nothing to disclose.

Chief Editor

Carlos J Lavernia, MD, FAAOS, Adjunct Clinical Professor, Department of Orthopedic Surgery, University of Miami School of Medicine; Medical Director, Orthopedic Institute at Mercy Hospital
Carlos J Lavernia, MD, FAAOS is a member of the following medical societies: American Academy of Orthopaedic Surgeons, American Association of Hip and Knee Surgeons, Arthritis Foundation, Biomedical Engineering Society, Florida Orthopaedic Society, and Orthopaedic Research Society
Disclosure: Zimmer Stock Implant Designer

 
 
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