title: Bone marrow lesions detected by specific combination of MRI sequences are associated with severity of osteochondral degeneration.
abstract: BACKGROUND
  Bone marrow lesions (BMLs) are useful diagnostic and prognostic markers in knee osteoarthritis (OA), but what they represent at the tissue level remains unclear. The aim of this study was to provide comprehensive tissue characterization of BMLs detected using two specific MRI sequences.
  
  
  METHODS
  Tibial plateaus were obtained from 60 patients (29 females, 31 males), undergoing knee arthroplasty for OA. To identify BMLs, MRI was performed ex vivo using T1 and PDFS-weighted sequences. Multi-modal tissue level analyses of the osteochondral unit (OCU) were performed, including cartilage volume measurement, OARSI grading, micro-CT analysis of bone microstructure, routine histopathological assessment and quantitation of bone turnover indices.
  
  
  RESULTS
  BMLs were detected in 74 % of tibial plateaus, the remainder comprising a No BML group. Of all BMLs, 59 % were designated BML 1 (detected only by PDFS) and 41 % were designated BML 2 (detected by both PDFS + T1). The presence of a BML was related to degeneration of the OCU, particularly within BML 2. When compared to No BML, BML 2 showed reduced cartilage volume (p = 0.008), higher OARSI scores (p = 0.004), thicker subchondral plate (p = 0.002), increased trabecular bone volume and plate-like structure (p = 0.0004), increased osteoid volume (p = 0.002) and thickness (p = 0.003), more bone marrow oedema (p = 0.03), fibrosis (p = 0.002), necrosis (p = 0.01) and fibrovascular cysts (p = 0.04). For most measures, BML 1 was intermediate between No BML and BML 2.
  
  
  CONCLUSIONS
  BMLs detected by specific MRI sequences identify different degrees of degeneration in the OCU. This suggests that MRI characteristics of BMLs may enable identification of different BML phenotypes and help target novel approaches to treatment and prevention of OA.
authors.affiliation: Discipline of Orthopaedics and Trauma, The University of Adelaide, Adelaide, Australia. dzenita.muratovic@adelaide.edu.au.|Bone and Joint Research Laboratory, SA Pathology, Frome Road, Adelaide, 5000, Australia. dzenita.muratovic@adelaide.edu.au.
authors.forename: Dzenita
authors.initials: D
authors.lastname: Muratovic
authors.affiliation: Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia. flavia.cicuttini@monash.edu.
authors.forename: Flavia
authors.initials: F
authors.lastname: Cicuttini
authors.affiliation: Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia. anita.wluka@monash.edu.
authors.forename: Anita
authors.initials: A
authors.lastname: Wluka
authors.affiliation: Discipline of Orthopaedics and Trauma, The University of Adelaide, Adelaide, Australia. david.findlay@adelaide.edu.au.
authors.forename: David
authors.initials: D
authors.lastname: Findlay
authors.affiliation: Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia. yuanyuan.wang@monash.edu.au.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Anatomical Pathology, SA Pathology, Adelaide, Australia. sophia.otto@sa.gov.au.
authors.forename: Sophia
authors.initials: S
authors.lastname: Otto
authors.affiliation: Department of Radiology, Royal Adelaide Hospital, Adelaide, Australia. jamie.taylor@sa.gov.au.
authors.forename: David
authors.initials: D
authors.lastname: Taylor
authors.affiliation: Bone and Joint Research Laboratory, SA Pathology, Frome Road, Adelaide, 5000, Australia. julia.humphries@sa.gov.au.
authors.forename: Julia
authors.initials: J
authors.lastname: Humphries
authors.affiliation: Bone and Joint Research Laboratory, SA Pathology, Frome Road, Adelaide, 5000, Australia. olivia.lee@sa.gov.au.
authors.forename: Yearin
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Adelaide Microscopy, The University of Adelaide, Adelaide, Australia. agatha.labrinidis@adelaide.edu.au.
authors.forename: Agatha
authors.initials: A
authors.lastname: Labrinidis
authors.affiliation: Adelaide Microscopy, The University of Adelaide, Adelaide, Australia. ruth.williams@adelaide.edu.au.
authors.forename: Ruth
authors.initials: R
authors.lastname: Williams
authors.affiliation: Discipline of Orthopaedics and Trauma, The University of Adelaide, Adelaide, Australia. julia.kuliwaba@adelaide.edu.au.|Bone and Joint Research Laboratory, SA Pathology, Frome Road, Adelaide, 5000, Australia. julia.kuliwaba@adelaide.edu.au.
authors.forename: Julia
authors.initials: J
authors.lastname: Kuliwaba
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001853:Bone Marrow / Q000473:pathology*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology*