title: Magnetic resonance imaging evaluation of L5-s1 intervertebral disc degeneration in Japanese women.
abstract: METHODS
  Retrospective case series.
  
  
  OBJECTIVE
  To calculate the prevalence of L5-S1 intervertebral disc degeneration (IDD) by evaluating gynecological disease findings, obtained by pelvic magnetic resonance imaging (MRI), and reveal the risk factors for IDD by analyzing its relationship with age, sacral structure, body mass index (BMI), number of deliveries, and intrapelvic space-occupying lesions.
  
  
  BACKGROUND
  Age, obesity, height, smoking history, occupation, and lumbosacral structure are reportedly the main factors of lumbar IDD. However, in women, the relationship of IDD with obstetric and gynecological history is unclear.
  
  
  METHODS
  The presence of L5-S1 IDD was evaluated on sagittal T2-weighted pelvic MRI during gynecological evaluations in 660 Japanese women. We measured the sacral table angle (STA), sacral kyphosis angle (SKA), and intrapelvic space-occupying lesion size. Age, height, weight, BMI, number of deliveries, lumbosacral structure, size of space-occupying lesions, and presence of uterine leiomyoma based on medical records were compared between the IDD-positive and IDD-negative groups.
  
  
  RESULTS
  Lumbosacral IDD was observed in 405 cases (61.4%), and its prevalence increased with age. Differences in age, height, weight, BMI, and number of deliveries between the IDD-positive and -negative groups were significant, but differences in STA, SKA, and presence of uterine leiomyoma and space-occupying lesion size were not. Logistic regression analysis indicated that age, BMI, and STA were risk factors for lumbosacral IDD.
  
  
  CONCLUSIONS
  Age is the biggest risk factor for lumbosacral IDD in Japanese women, with BMI and STA also contributing to its development. However, SKA and obstetric and gynecological history were not significantly involved.
authors.affiliation: Department of Radiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hagiwara
authors.affiliation: Department of Radiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Shibata
authors.affiliation: Department of Radiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
authors.forename: Hideya
authors.initials: H
authors.lastname: Sakakibara
authors.affiliation: Department of Radiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
authors.forename: Tomio
authors.initials: T
authors.lastname: Inoue
keywords: Body mass index; Intervertebral disc degeneration; Lumbosalral region; Magnetic resonance imaging; Reproductive history