title: [Bone Marrow Lesion - Risk-Factors and Pathophysiological Relevance: Systematic Review].
abstract: OBJECTIVE
  The objective of this systematic review and meta-analysis is to obtain information about risks and associated factors for knee symptoms and the progression of osteoarthritis in idiopathic bone marrow lesion (BML).
  
  
  METHODS
  The primary search on 31. 12. 2013 included the databases PubMed, EMBASE, Web of Science and Cochrane by the search strategy [[bone marrow edema] AND [knee]]. This review was continuously updated up to 31. 10. 2015.
  
  
  RESULTS
  A total of 30 studies (from 1331 primary findings) were included in the final evaluation. The mean frequency of BML in all studies was 37.2 %. The occurrence of BML was strongly dependent on the MRI technique used (1.0 to 3.0 T). In longitudinal studies, the incidence of BML was 3.2 (95 % CI 1.7-6.3)/1000 person-months. Weakly associated factors included female gender (OR = 1.3 [95 % CI 1.1-1.7], p = 0.009), increasing age (OR = 1.05 [95 % CI 0.9-1.3], p = 0.127), and overweight or obesity (OR = 1.1 [95 % CI 1.1-1.2]; p < 0.01). BMLs are significantly associated with cartilage lesions (OR = 5.5 [95 % CI 1.3-22.5]). Radiological osteoarthritis is also significantly associated with the development of BML (OR = 3.6 [95 % CI 1.2-10.6]) and the progression of osteoarthritis within a 3-year interval (OR = 4.4 [95 % CI 3.1-6.4]).
  
  
  CONCLUSIONS
  The occurrence of BML is an important index for severe degenerative pathologies in the knee. It appears that MRT symptoms predict the progression of the disease. The clinical relevance and possible consequences for treatment are unclear.
authors.affiliation: Unfallchirurgie und Orthopädie, Praxisklinik für Unfallchirurgie und Orthopädie, Eisenach.
authors.forename: G
authors.initials: G
authors.lastname: Spahn
authors.affiliation: Unfallchirurgie und Orthopädie, Praxisklinik für Unfallchirurgie und Orthopädie, Eisenach.
authors.forename: M
authors.initials: M
authors.lastname: Biehl
authors.affiliation: Klinik für Unfall-, Hand- und Wiederherstellungschirurgie, Universitätsklinikum Jena.
authors.forename: G O
authors.initials: GO
authors.lastname: Hofmann
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001855:Bone Marrow Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015984:Causality; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution