title: The Influence of Lumbar Spinal Subtype on Lumbar Intervertebral Disc Degeneration in Young and Middle-Aged Adults.
abstract: METHODS
  Retrospective cohort study.
  
  
  OBJECTIVE
  To identify whether an in vivo correlation exists between lumbar spinal subtype (LSS) and lumbar disc degeneration (LDD) in young adults.
  
  
  BACKGROUND
  Lumbar disc degeneration has largely been ascribed to biomechanical and structural alterations to the disc, which are attributed to aging and pathological physical loading. Sagittal alignment in the asymptomatic spine has also been considered. A biomechanical study by Roussouly and Pinheiro-Franco proposed level-specific patterns in LDD. To date, no in vivo correlation between the LSS and LDD has been established.
  
  
  METHODS
  The authors screened 608 consecutive patients over 5.3 years. Lumbar spinal subtype and pelvic parameters were collected from standing lumbar radiographs and were categorized using the classification of Roussouly and Pinheiro-Franco. Lumbar disc degeneration at all lumbar intervertebral levels was classified using criteria of Pfirrmann et al. A stratified disc degeneration score was derived for each patient. Lumbar disc degeneration in type I, II, and IV LSS was compared using chi-square test. Pelvic incidence was correlated with stratified disc degeneration score using Spearman R, to determine whether a high PI was protective against LDD. Statistical significance was accepted at p < .05.
  
  
  RESULTS
  A total of 139 patients were included, with 91 females and a mean age of 32.6 years (range, 13-49 years). For LSS grades I to IV, there were 10 (7.3%), 43 (30.9%), 50 (35.9%), and 36 (25.9%) patients, respectively. The proportion of high-grade (Pfirrmann grades IV and V) LDD increased distally toward the lower intervertebral levels, affecting 2.88%, 2.9%, 5%, 9.4%, 33.1%, and 54% of discs at each sequential lumbar level from T12-L1 to L5-S1, respectively. Age but not gender was statistically significant for higher-grade LDD (p < .0001 and p = .442, respectively). Pelvic incidence across all LSS grades was not significantly correlated with stratified disc degeneration score (Spearman R = 0.0933; p = .335). No LSS (type I-IV) reached statistical significance for a specific pattern of LDD.
  
  
  CONCLUSIONS
  In this study, LSS was not statistically significantly correlated with LDD, nor was a high pelvic incidence protective against LDD.
authors.affiliation: Department of Spinal Surgery, Frenchay Hospital, North Bristol NHS Trust, Beckspool Road, Frenchay, Bristol BS16 1LE, UK. Electronic address: alextorrie99@hotmail.com.
authors.forename: P A G
authors.initials: PA
authors.lastname: Torrie
authors.affiliation: Department of Spinal Surgery, Frenchay Hospital, North Bristol NHS Trust, Beckspool Road, Frenchay, Bristol BS16 1LE, UK.
authors.forename: G
authors.initials: G
authors.lastname: McKay
authors.affiliation: Department of Spinal Surgery, Frenchay Hospital, North Bristol NHS Trust, Beckspool Road, Frenchay, Bristol BS16 1LE, UK.
authors.forename: R
authors.initials: R
authors.lastname: Byrne
authors.affiliation: Department of Spinal Surgery, Frenchay Hospital, North Bristol NHS Trust, Beckspool Road, Frenchay, Bristol BS16 1LE, UK.
authors.forename: S A C
authors.initials: SA
authors.lastname: Morris
authors.affiliation: Department of Spinal Surgery, Frenchay Hospital, North Bristol NHS Trust, Beckspool Road, Frenchay, Bristol BS16 1LE, UK.
authors.forename: I J
authors.initials: IJ
authors.lastname: Harding
keywords: Etiology; Lumbar disc degeneration; Lumbar spine subtype