title: Association between bone mineral density and lumbar disc degeneration.
abstract: OBJECTIVE
  Higher vertebral bone mineral density (BMD) has been found to be related with lumbar disc degeneration (LDD), while relationship between femoral neck BMD and LDD remains controversial. The aim of our research was to study the relationship between LDD and BMD of the lumbar spine and femoral neck.
  
  
  METHODS
  The study population consisted of 168 postmenopausal women (aged 63.3-75.0 years, mean 68.6 years) from the prospective OSTPRE and OSTPRE-FPS study cohorts. The severity of LDD was graded from T2-weighted MRI images using the five-grade Pfirrmann classification. Four vertebral levels (L1-L4) were studied (total 672 discs). The association between lumbar BMD and Z-score and the severity of LDD was studied separately for each vertebral level with AN(C)OVA analysis, using potential confounders as covariates.
  
  
  RESULTS
  Higher lumbar BMD and Z-score were associated with more severe LDD at all studied levels (L1-L4): between L4-L5 disc and L4 BMD (p=0.044) and L4 Z-score (p=0.052), between L2-L3 disc and L3 BMD (p=0.001) and at all other levels (p<0.001). The mean degeneration grade of the studied discs was associated with the mean L1-L4 BMD and Z-score (p<0.001). Statistical significance of any result did not alter after controlling for confounding factors. There was no significant association between femoral neck BMD and LDD.
  
  
  CONCLUSIONS
  Higher lumbar BMD/Z-score were associated with more severe LDD. There was no significant association between femoral neck BMD and disc degeneration. Femoral neck BMD may be a more reliable measurement for diagnosing osteoporosis in postmenopausal women with degenerative changes in the lumbar spine.
authors.affiliation: Bone and Cartilage Research Unit, Surgery, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland. Electronic address: saksalo@student.uef.fi.
authors.forename: Sami
authors.initials: S
authors.lastname: Salo
authors.affiliation: Department of Neurosurgery, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Leinonen
authors.affiliation: Bone and Cartilage Research Unit, Surgery, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
authors.forename: Toni
authors.initials: T
authors.lastname: Rikkonen
authors.affiliation: Department of Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Pauli
authors.initials: P
authors.lastname: Vainio
authors.affiliation: Department of Radiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Marttila
authors.affiliation: Bone and Cartilage Research Unit, Surgery, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; Lapland Hospital District, Rovaniemi, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Honkanen
authors.affiliation: Bone and Cartilage Research Unit, Surgery, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; Department of Obstetrics and Gynecology, Kuopio University Hospital, Finland.
authors.forename: Marjo
authors.initials: M
authors.lastname: Tuppurainen
authors.affiliation: Bone and Cartilage Research Unit, Surgery, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; Department of Orthopedics, Traumatology and Hand Surgery, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Kröger
authors.affiliation: Bone and Cartilage Research Unit, Surgery, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; Department of Orthopedics, Traumatology and Hand Surgery, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Joonas
authors.initials: J
authors.lastname: Sirola
mesh_terms: D000368:Aged; D015519:Bone Density; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000473:pathology*; D012720:Severity of Illness Index; D016387:Women's Health
keywords: Bone mineral density; Intervertebral disc degeneration; Lumbar spine; Osteoporosis; Postmenopausal women