title: Medial extrusion of the posterior segment of medial meniscus is a sensitive sign for posterior horn tears.
abstract: BACKGROUND
  To evaluate medial extrusion of the posterior segment of the medial meniscus in posterior horn tears.
  
  
  METHODS
  This study enrolled 72 patients without medial meniscal tears (group N), 72 patients with medial meniscal tears without posterior horn tears (group PH-), 44 patients with posterior horn tears of the medial meniscus (group PH+). All meniscal tears were confirmed by arthroscopy. Medial extrusion of the middle segment and the posterior segment was measured on coronal MRIs.
  
  
  RESULTS
  Extrusions of both middle and posterior segments in groups PH- and PH+ (middle segment; 2.94±1.51 mm for group PH- and 3.75±1.69 mm for group PH+, posterior segment; 1.85±1.82 mm for group PH- and 4.59±2.74 mm for group PH+) were significantly larger than those in group N (middle segment; 2.04±1.20, posterior segment; 1.21±1.86). Both indicators of extrusion in group PH+ were larger than those in group PH-. In the early OA category, neither middle nor posterior segment in group PH- extruded more than in group N. However, only the posterior segment in group PH+ extruded significantly more than in group N. Multiple lineal regression analyses revealed that posterior segment extrusion was strongly correlated with the posterior horn tears (p<0.001) among groups PH- and PH+.
  
  
  CONCLUSIONS
  The newly presented indicator for extrusion of the posterior segment of the medial meniscus is associated with posterior horn tears in comparison with the extrusion of the middle segment, especially in the early stages of osteoarthritis.
  
  
  METHODS
  Level II--Diagnostic Study.
authors.affiliation: The Department of Orthopaedic Surgery, Enshu Hospital, Hamamatsu, Shizuoka, Japan. Electronic address: t-ohishi@ken.ja-shizuoka.or.jp.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ohishi
authors.affiliation: The Department of Orthopaedic Surgery, Enshu Hospital, Hamamatsu, Shizuoka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Suzuki
authors.affiliation: The Department of Orthopaedic Surgery, Enshu Hospital, Hamamatsu, Shizuoka, Japan.
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: The Department of Orthopaedic Surgery, Enshu Hospital, Hamamatsu, Shizuoka, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Banno
authors.affiliation: The Department of Orthopaedic Surgery, Enshu Hospital, Hamamatsu, Shizuoka, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: The Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Matsuyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001182:Arthroscopy; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis* / Q000601:surgery; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000145:classification; D015203:Reproducibility of Results; D000070600:Tibial Meniscus Injuries; D055815:Young Adult
keywords: Magnetic resonance image; Medial meniscus; Meniscal extrusion; Posterior horn tear; Posterior segment