title: The effect of compressive force applied to the intervertebral disc in vivo. A study of proteoglycans and collagen.
abstract: METHODS
  Coil springs were stretched and attached to produce a compressive force across the lumbar intervertebral discs of dogs for up to 27 weeks.
  
  
  OBJECTIVE
  To test the hypothesis that a high compressive force applied over a period of time affects the production of proteoglycans and collagen by the intervertebral disc cells.
  
  
  BACKGROUND
  It is a commonly held belief that high forces applied to the intervertebral disc, and to joints in general, play a role in causing degeneration.
  
  
  METHODS
  Pairs of stainless steel coil springs were stretched and attached to produce a compressive force across the lumbar intervertebral discs (L1-L2 and L3-L4) of 16 dogs. Dogs were killed between 13 and 27 weeks after the springs were attached. The discs (L1-L2 and L3-L4) were excised and assessed using immunohistochemical analyses and enzyme-linked immunosorbent assay; T13-L1 and L4-L5 were used as controls.
  
  
  RESULTS
  The main result relates to a group effect in the six dogs, assessed using enzyme-linked immunosorbent assay, that were generally at the highest values of force for the greatest number of weeks. For the nucleus, but not the anulus, Spearman rank correlations revealed a strong correlation between increases in force and force-weeks (force multiplied by number of weeks) and increases in collagen type I accompanied by decreases in proteoglycans, chondroitin sulfate, and collagen type II for both experimental discs (L1-L2 and L3-L4), as compared with corresponding values in the controls (T13-L1 and L4-L5). In other words, as either the force or the force-weeks increased, the effect on the nucleus became greater.
  
  
  CONCLUSIONS
  A high compressive force applied to the disc over a period of time initiates changes in proteoglycans and collagen.
authors.affiliation: Department of Orthopaedics, Emory University, Atlanta, Georgia. william_hutton@emory.org
authors.forename: W C
authors.initials: WC
authors.lastname: Hutton
authors.forename: Y
authors.initials: Y
authors.lastname: Toribatake
authors.forename: W A
authors.initials: WA
authors.lastname: Elmer
authors.forename: T M
authors.initials: TM
authors.lastname: Ganey
authors.forename: K
authors.initials: K
authors.lastname: Tomita
authors.forename: T E
authors.initials: TE
authors.lastname: Whitesides
mesh_terms: D053674:Aggrecans; D000818:Animals; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D002809:Chondroitin Sulfates / Q000378:metabolism; D003094:Collagen / Q000378:metabolism*; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D007403:Intervertebral Disc / Q000378:metabolism*; D037181:Lectins, C-Type; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000378:metabolism / Q000601:surgery; D008297:Male; D011509:Proteoglycans; D011859:Radiography; D013122:Spinal Diseases / Q000209:etiology / Q000378:metabolism*; D013314:Stress, Mechanical
chemical_list: D053674:Aggrecans; D011508:Chondroitin Sulfate Proteoglycans; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D002809:Chondroitin Sulfates; D003094:Collagen