title: Collagenous Ultrastructure of the Discoid Meniscus: A Transmission Electron Microscopy Study.
abstract: The collagen ultrastructure of the discoid lateral meniscus (DLM) has not been precisely defined.
  
  
  
  To investigate the ultrastructure of the DLM, focusing on its collagen fibers, and to compare the collagen net architecture between intact and torn DLMs using the Collagen Meniscal Architecture (CMA) scoring system.
  
  
  
  Descriptive laboratory study.
  
  
  
  Thirty specimens were taken from 30 patients with a diagnosis of a complete DLM using a 1-piece technique. The collagen ultrastructure of the DLMs was assessed with transmission electron microscopy. To evaluate the meniscal ultrastructure, the degree of collagen disruption, intrafibrillar edema, loss of banding, degree of collagen packing, and fibril size variability were assessed and graded from 1 (normal) to 3 (severe disarray) according to the CMA scoring system. The DLM specimens were divided into 3 groups according to the intrasubstance tear: the intact group (group I) had no tear; the simple tear group (group S) had a radial, longitudinal, or horizontal tear; and the complicated tear group (group C) had a complicated horizontal tear. Intact normal meniscus specimens (group N) were used as the control group.
  
  
  
  There were 10 specimens in group I, 8 in group S, 12 in group C, and 13 in group N. In group I, there were 5 grade 1 and 5 grade 2 menisci; group S had 2 grade 1, 3 grade 2, and 3 grade 3 menisci; group C had 1 grade 1, 4 grade 2, and 7 grade 3 menisci; and group N had 4 grade 1, 7 grade 2, and 2 grade 3 menisci. A significant difference in the CMA score was observed between the 4 groups ( P = .009). The median CMA score was significantly lower in group I (2; range, 1-4) than in group S (4; range, 2-7) ( P = .041) and group C (4.25; range, 1.5-7) ( P = .018). No significant difference was found between groups S, C, and N.
  
  
  
  Variability existed in the collagen ultrastructure of the DLM, and some DLMs showed a nearly normal ultrastructural pattern. The degree of density and disorganization of the collagen architecture in the DLM was related to the tear.
  
  
  
  The study results might provide a histological background for partial meniscectomy in the treatment of a symptomatic DLM.
authors.affiliation: Department of Pathology, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Republic of Korea.
authors.forename: Young-Hee
authors.initials: YH
authors.lastname: Choi
authors.affiliation: Department of Orthopaedic Surgery, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Republic of Korea.
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Seo
authors.affiliation: Department of Orthopaedic Surgery, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Republic of Korea.
authors.forename: Jong Mun
authors.initials: JM
authors.lastname: Ha
authors.affiliation: Department of Orthopaedic Surgery, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Republic of Korea.
authors.forename: Koo Hyun
authors.initials: KH
authors.lastname: Jung
authors.affiliation: Department of Orthopaedic Surgery, Seoul Sacred Heart General Hospital, Seoul, Republic of Korea.
authors.forename: Jeehyoung
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Dongtan Sacred Heart Hospital, Hallym University Medical Center, Hwaseong, Republic of Korea.
authors.forename: Si Young
authors.initials: SY
authors.lastname: Song
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000648:ultrastructure*; D006801:Humans; D008592:Menisci, Tibial / Q000002:abnormalities / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D055815:Young Adult
chemical_list: D003094:Collagen
keywords: CMA scoring system; collagen ultrastructure; discoid meniscus; transmission electron microscopy