Bisphosphonate treatment delays stress fracture remodeling in the rat ulna

J Orthop Res. 2011 Dec;29(12):1827-33. doi: 10.1002/jor.21464. Epub 2011 May 19.


Because bisphosphonates (BPs) are potent inhibitors of bone resorption, we hypothesized that they would retard direct remodeling of stress fractures. The aim of this study was to determine the effect of risedronate on direct remodeling and woven bone callus formation following stress fracture formation in the rat ulna. In 135 adult female Wistar rats, cyclic loading of the ulna created stress fractures. Rats were treated daily with oral saline, or risedronate at 0.1 or 1.0 mg/kg. From each bone, histomorphometry was performed on sections stained with toluidine blue at a standard level along the fracture. The high dose of risedronate caused a significant decrease in the percentage of repaired stress fracture and bone resorption along the stress fracture line at 6 and 10 weeks after loading (p < 0.05). At this dose, intracortical resorption was significantly reduced at 10 weeks after loading and intracortical new bone area was significantly reduced at 6 and 10 weeks. Woven bone formation and consolidation phases of stress fracture repair were not affected by low or high doses of risedronate. In conclusion, high dose bisphosphonate treatment impaired healing of a large stress fracture line by reducing the volume of bone resorbed and replaced during remodeling. We also confirmed that periosteal callus formation was not adversely affected by risedronate treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Density Conservation Agents / pharmacology*
  • Bone Remodeling / drug effects*
  • Bony Callus / drug effects
  • Diaphyses / drug effects
  • Diaphyses / injuries
  • Diphosphonates / pharmacology
  • Dose-Response Relationship, Drug
  • Etidronic Acid / analogs & derivatives*
  • Etidronic Acid / pharmacology
  • Female
  • Fractures, Stress / drug therapy*
  • Periosteum / drug effects
  • Rats
  • Rats, Wistar
  • Risedronic Acid
  • Ulna Fractures / drug therapy*


  • Bone Density Conservation Agents
  • Diphosphonates
  • Risedronic Acid
  • Etidronic Acid