title: Identification of lumbar disc disease hallmarks: a large cross-sectional study.
abstract: BACKGROUND
  Lumbar disc disease has a disabling impact on global people with heavy burden on society, mainly consisting of lumbar disc degeneration (LDD) and lumbar disc herniation (LDH). The recently released lumbar disc nomenclature version 2.0 deepens our understandings on the diseases. Consequently, there is an urgent need to clarify the occurrence and distribution features of LDD and LDH in a large-scale sample in terms of the novel version.
  
  
  OBJECTIVE
  We asked: (1) Is there a difference in the occurrence and distribution hallmarks of LDD and LDH in a population-based large-scale sample? (2) Does the novel nomenclature version bring novel vision on lumbar disc disease?
  
  
  METHODS
  Five thousand two hundred eighty-eight consecutive cases (26,440 lumbar discs) undergoing lumbar spine MRI were retrospectively included from Jan 2008 to Dec 2010 in a territory university hospital. Five hundred nine cases were excluded. There were 2727 males (51.57%) and 2561 females (48.43%) with a mean age of 43.73 years. Both T1 and T2 weighted lumbar MRI images from L1/2 to L5/S1 were profoundly analyzed in axial and sagittal planes. We classified lumbar discs in terms of version 2.0.
  
  
  RESULTS
  The occurrence of LDH and LDD was 14.18 and 44.23% in average, respectively. Notably, lumbar spine discs were more prone to LDD than LDH. L4/5 was the most frequent level in terms of LDH (26.08%) and LDD (56.09%), followed by L5/S1 (LDH: 24.09%; LDD: 55.33%), then L3/4, L2/3 and L1/2 in ranking order. The prevalence of LDH and LDD in upper lumbar discs from L1/2 to L3/4 was significant lower than the average prevalence rate (P< 0.05). The mean age was 24.70 (±14.81) years for normal lumbar discs; 49.76 (±14.95) years for LDD; 37.01 (±12.91) years for LDH; 51.31(±15.00) years for LDD and LDH (P< 0.05). Modic changes, HIZ, spondylosis deformans and decreased disc height were linked with older age; whereas Schmorl node and lumbar disc sequestration were not associated with age (P< 0.05).
  
  
  CONCLUSIONS
  The prevalence of LDD is 44.23%, higher than LDH as 14.18%. L4/5 and L5/S1 are the most frequent involved segments for the majority of lumbar disc diseases. Schmorl node occurs (1.6%) more frequently in upper lumbar spine, independent of age. Modic changes (0.87%) are closely related with older age.
  
  
  CONCLUSIONS
  When diagnosing and treating lumbar disc disease, it might be important to consider the updated nomenclature of LDD and LDH. Our study provides additional novel vision on the features of LDD and LDH in a large-scale sample based on the nomenclature of novel version.
authors.affiliation: Department of Orthopaedics, Baoji Municipal Central Hospital, Baoji, 721008 Shaanxi Province People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, 127 Changle Western Road, Xi'an, 710032 People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Department of Orthopaedics, The Third Hospital of PLA, Baoji, 721004 Shaanxi Province People's Republic of China.
authors.forename: Feng-Liang
authors.initials: FL
authors.lastname: Wang
authors.affiliation: Brigade of Undergraduates, Fourth Military Medical University, Xi'an, 710032 People's Republic of China.
authors.forename: Yong-Feng
authors.initials: YF
authors.lastname: Yang
authors.affiliation: Brigade of Undergraduates, Fourth Military Medical University, Xi'an, 710032 People's Republic of China.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Brigade of Undergraduates, Fourth Military Medical University, Xi'an, 710032 People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Brigade of Undergraduates, Fourth Military Medical University, Xi'an, 710032 People's Republic of China.
authors.forename: You-Lin
authors.initials: YL
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, 127 Changle Western Road, Xi'an, 710032 People's Republic of China.
authors.forename: Xiao-Juan
authors.initials: XJ
authors.lastname: Shi
authors.affiliation: Department of Health Service, School of Public Health, Fourth Military Medical University, Xi'an, 710032 People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wan
authors.affiliation: Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, 127 Changle Western Road, Xi'an, 710032 People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, 127 Changle Western Road, Xi'an, 710032 People's Republic of China.
authors.forename: Meng-Qiao
authors.initials: MQ
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, Baoji Municipal Central Hospital, Baoji, 721008 Shaanxi Province People's Republic of China.
authors.forename: Chun-Guang
authors.initials: CG
authors.lastname: Zuo
authors.affiliation: Department of Orthopaedics, Xijing Hospital, Fourth Military Medical University, 127 Changle Western Road, Xi'an, 710032 People's Republic of China.
authors.forename: Hai-Qiang
authors.initials: HQ
authors.lastname: Wang