title: Predictors of degenerative medial meniscus extrusion: radial component and knee osteoarthritis.
abstract: OBJECTIVE
  the purpose of this study was to determine the effect of a radial tear on degenerative medial meniscus posterior horn tear extrusion and to identify predictors of medial meniscus extrusion.
  
  
  METHODS
  we reviewed the records of 102 knees with medial meniscus posterior horn tears and degeneration that underwent a partial meniscectomy. Tears were classified as root (n = 17) and non-root (n = 85) tears, or as radial (n = 46) and non-radial (n = 56) tears. Groups were compared in terms of absolute and relative meniscal extrusion, and the proportion of knees with major (> 3 mm) extrusion. Multiple regression analysis was used to identify predictors of extrusion.
  
  
  RESULTS
  the radial group had greater mean absolute (4 ± 1 vs. 3 ± 1 mm, P = 0.001) and relative (31 ± 11 vs. 23 ± 12%, P = 0.031) extrusion than the non-radial group. The radial group also had a greater proportion of major extrusions than the non-radial group (74% vs. 26%; P = 0.016). In contrast, the root tear and non-root tear groups were similar in terms of mean absolute (3 ± 1 vs. 3 ± 1 mm, P = n.s.) and relative (30 ± 7 vs. 26 ± 13%; P = n.s.) extrusion and in terms of proportion with major extrusions (59 vs. 55%; P = n.s.). Extrusion was found to be associated with a similar strength with both the presence of a radial component and the preoperative Kellgren-Lawrence grade.
  
  
  CONCLUSIONS
  meniscal extrusion was greater and more severe in knees with a radial tear component than in knees without a radial component. The incidence and degree of major extrusion was similar in knees with root tears and non-root tears. A radial component and knee osteoarthritis severity were similarly predictive of absolute and relative extrusion. Meniscal extrusion in osteoarthritic knees was associated not only with degenerative meniscal tear but also with osteoarthritis severity. Therefore, arthroscopic meniscal procedures, especially meniscal repair, should be cautiously considered in patients with meniscal extrusion.
authors.affiliation: Department of Orthopaedic Surgery, Korea University, College of Medicine, Anam Hospital, Seoul, Korea. eoak22@empal.com
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Bum-Sik
authors.initials: BS
authors.lastname: Lee
authors.forename: Jong-Min
authors.initials: JM
authors.lastname: Kim
authors.forename: Kyung-Sook
authors.initials: KS
authors.lastname: Yang
authors.forename: Eun-Jong
authors.initials: EJ
authors.lastname: Cha
authors.forename: Ji-Hun
authors.initials: JH
authors.lastname: Park
authors.forename: Seong-Il
authors.initials: SI
authors.lastname: Bin
mesh_terms: D000328:Adult; D000368:Aged; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000473:pathology; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D012189:Retrospective Studies