title: Changes in vertebral strength-density and energy absorption-density relationships following bisphosphonate treatment in beagle dogs.
abstract: We aimed to determine the effects of bisphosphonates on mechanical properties independent of changes in bone density. Our results show that at equivalent bone densities, vertebrae from beagles treated with bisphosphonate have equivalent bone strength and reduced bone energy absorption compared to those from untreated animals.
  
  
  BACKGROUND
  Assessing the relationship between mechanical properties and bone density allows a biomechanical evaluation of bone quality, with differences at a given density indicative of altered quality. The purpose of this study was to evaluate the strength-density and energy absorption-density relationships in vertebral bone following a one-year treatment with clinical doses of two different bisphosphonates in beagle dogs.
  
  
  METHODS
  Areal bone mineral density (aBMD) and compressive mechanical properties (ultimate load and energy absorption) were assessed on lumbar vertebrae from skeletally mature beagle dogs treated with vehicle (VEH), alendronate (ALN), or risedronate (RIS). Relationships among properties were assessed using analyses of covariance.
  
  
  RESULTS
  Neither treatment altered the strength-density relationship compared to VEH, suggesting increases in vertebral strength with bisphosphonate-treatment are explained by increased density. The energy absorption-density relationship was altered by ALN, resulting in significantly lower energy absorption capacity at a given aBMD compared to both VEH (-22%) and RIS (-14%).
  
  
  CONCLUSIONS
  These data document that after adjusting for increased aBMD, vertebrae from animals treated with bisphosphonates have similar strength as those from untreated animals. Conversely, when adjusted for increased aBMD, alendronate treatment, but not risedronate treatment, significantly reduces the energy required for vertebral fracture, indicative of an alteration in bone quality.
authors: Dept. of Anatomy and Cell Biology, MS 5035, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202, USA. matallen@iupui.edu
authors: M R
authors: MR
authors: Allen
authors: D B
authors: DB
authors: Burr
mesh_terms: D019386:Alendronate / Q000494:pharmacology; D000818:Animals; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D019245:Compressive Strength; D004164:Diphosphonates / Q000494:pharmacology*; D004285:Dogs; D012968:Etidronic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D008159:Lumbar Vertebrae / Q000187:drug effects*; D023421:Models, Animal; D000068296:Risedronic Acid
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D000068296:Risedronic Acid; D012968:Etidronic Acid; D019386:Alendronate
references: J Bone Miner Res. 2004 Feb;19(2):330-7
references: 14969404
references: Bone. 2000 Nov;27(5):687-94
references: 11062357
references: JAMA. 1999 Aug 18;282(7):637-45
references: 10517716
references: Bone. 1993 Jul-Aug;14(4):595-608
references: 8274302
references: JAMA. 1999 Oct 13;282(14 ):1344-52
references: 10527181
references: J Bone Miner Res. 2006 Jul;21(7):1106-12
references: 16813531
references: J Bone Miner Res. 2006 Aug;21(8):1248-55
references: 16869723
references: Bone. 2004 Apr;34(4):599-604
references: 15050889
references: J Biomech. 2004 Apr;37(4):549-56
references: 14996567
references: Calcif Tissue Int. 2001 Apr;68(4):205-10
references: 11353945
references: Bone. 2001 May;28(5):524-31
references: 11344052
references: J Bone Miner Res. 2005 Jan;20(1):141-51
references: 15619680
references: Bone. 2006 Nov;39(5):1130-5
references: 16814622
references: Bone. 2006 Dec;39(6):1173-81
references: 16876493
references: Bone. 2001 Jan;28(1):133-9
references: 11165955
references: Bone. 2001 Aug;29(2):185-91
references: 11502482
references: Bone. 2006 Oct;39(4):872-9
references: 16765660
references: Lancet. 1996 Dec 7;348(9041):1535-41
references: 8950879
references: Bone. 2002 Jul;31(1):8-11
references: 12110405
references: J Biomech. 1996 Feb;29(2):257-60
references: 8849821