title: A population-based study of juvenile disc degeneration and its association with overweight and obesity, low back pain, and diminished functional status.
abstract: BACKGROUND
  Little is known regarding juvenile disc degeneration in individuals with normal spinal alignment. Consequently, the purpose of this study was to assess the prevalence, determinants, and clinical relevance associated with juvenile disc degeneration of the lumbar spine in individuals without spinal deformities.
  
  
  METHODS
  A cross-sectional assessment of disc degeneration in juveniles was performed as part of a population-based study of 1989 Southern Chinese volunteers. Adolescents and young adults from thirteen to twenty years of age were defined as "juveniles." Juvenile subjects with no spinal deformity (n = 83) were stratified into two groups, those with and those without juvenile disc degeneration. Sagittal T2-weighted magnetic resonance images (MRI) were evaluated for the presence and extent of disc degeneration as well as other spinal findings. Demographics were assessed and clinical profiles were collected with use of standardized questionnaires.
  
  
  RESULTS
  Juvenile disc degeneration was present in 35% (twenty-nine) of the juveniles without spinal deformity. Disc bulging or extrusion (p < 0.001), high-intensity zones on MRI (p = 0.040), and greater weight (p < 0.001) and height (p = 0.002) were significantly more prevalent in subjects with juvenile disc degeneration. Adjusted multivariate logistic regression modeling demonstrated that Asian-modified body-mass index (BMI) values in the overweight or obese range had a significant association with juvenile disc degeneration (odds ratio = 14.19; 95% confidence interval = 1.44 to 140.40; p = 0.023). Overweight and obese individuals had greater severity of disc degeneration than underweight and normal-weight individuals (p = 0.036). Furthermore, individuals with juvenile disc degeneration had an increased prevalence of low back pain and/or sciatica (p = 0.002), greater low back pain intensity (p < 0.001), diminished social functioning (p = 0.049), and greater physical disability (p < 0.05) than individuals without disc degeneration. The p value of <0.05 for physical disability represents both the physical function (p = 0.006) and the physical component (p = 0.032) of the SF-36.
  
  
  CONCLUSIONS
  This study demonstrated that the presence of juvenile disc degeneration was strongly associated with overweight and obesity, low back pain, increased low back pain intensity, and diminished physical and social functioning. Furthermore, an elevated BMI was significantly associated with increased severity of disc degeneration. This study has public health implications regarding overweight and obesity and the development of lumbar disc disease.
authors.affiliation: Department of Orthopaedics and Traumatology, University of Hong Kong, Hong Kong, SAR, China. dsamartzis@msn.com
authors.forename: Dino
authors.initials: D
authors.lastname: Samartzis
authors.forename: Jaro
authors.initials: J
authors.lastname: Karppinen
authors.forename: Florence
authors.initials: F
authors.lastname: Mok
authors.forename: Daniel Y T
authors.initials: DY
authors.lastname: Fong
authors.forename: Keith D K
authors.initials: KD
authors.lastname: Luk
authors.forename: Kenneth M C
authors.initials: KM
authors.lastname: Cheung
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D017668:Age of Onset; D015992:Body Mass Index; D002681:China / Q000453:epidemiology; D015897:Comorbidity; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D018450:Disease Progression; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis / Q000453:epidemiology*; D016015:Logistic Models; D017116:Low Back Pain / Q000175:diagnosis / Q000453:epidemiology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D051346:Mobility Limitation; D015999:Multivariate Analysis; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology; D016017:Odds Ratio; D050177:Overweight / Q000175:diagnosis / Q000453:epidemiology*; D010809:Physical Fitness / Q000502:physiology; D015995:Prevalence; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D055815:Young Adult