title: Delayed fracture healing in aged senescence-accelerated P6 mice.
abstract: BACKGROUND
  Osteoporosis is characterized by poor bone quality. However, it is still controversially discussed whether osteoporosis compromises fracture healing. Herein, we studied whether the course of healing of a femur fracture is affected by osteoporosis or age.
  
  
  METHODS
  Using the senescence-accelerated osteoporotic mouse, strain P6 (SAMP6), and a closed femur fracture model, we studied the process of fracture healing in 5- and 10-month-old animals, including biomechanical, histomorphometric, and protein biochemical analysis.
  
  
  RESULTS
  In five-month-old osteoporotic SAMP6 mice, bending stiffness, callus size, and callus tissue distribution as well as the concentrations of the bone formation marker osteocalcin and the bone resorption markers tartrate-resistant acid phosphatase form 5b (TRAP) and deoxypyridinoline (DPD) did not differ from that of non-osteoporotic, senescence-resistant, strain 1 (SAMR1) controls. In contrast, femur fractures in 10-month-old SAMP6 mice showed a significantly reduced bending stiffness and an increased callus size compared to fractures in age-matched SAMR1 controls. This indicates a delayed fracture healing in advanced age SAMP6 mice. The delay of fracture healing was associated with higher concentrations of TRAP and DPD. Significant differences in osteocalcin concentrations were not found between SAMP6 animals and SAMR1 controls.
  
  
  CONCLUSIONS
  In conclusion, the present study indicates that fracture healing in osteoporotic SAMP6 mice is not affected in five-month-old animals, but delayed in animals with an age of 10 months. This is most probably due to the increased osteoclast activity in advanced age SAMP6 animals.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University of Saarland, Homburg/Saar, Germany. tina.histing@uks.eu
authors.forename: Tina
authors.initials: T
authors.lastname: Histing
authors.forename: Swantje
authors.initials: S
authors.lastname: Kuntz
authors.forename: David
authors.initials: D
authors.lastname: Stenger
authors.forename: Claudia
authors.initials: C
authors.lastname: Scheuer
authors.forename: Patric
authors.initials: P
authors.lastname: Garcia
authors.forename: Joerg H
authors.initials: JH
authors.lastname: Holstein
authors.forename: Moritz
authors.initials: M
authors.lastname: Klein
authors.forename: Tim
authors.initials: T
authors.lastname: Pohlemann
authors.forename: Michael D
authors.initials: MD
authors.lastname: Menger
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000375:Aging / Q000235:genetics / Q000502:physiology*; D000596:Amino Acids / Q000652:urine; D000818:Animals; D001862:Bone Resorption / Q000503:physiopathology; D005264:Femoral Fractures / Q000150:complications / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D017102:Fracture Healing; D005596:Fractures, Closed / Q000150:complications / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D007527:Isoenzymes / Q000097:blood; D051379:Mice; D008817:Mice, Mutant Strains; D015675:Osteocalcin / Q000097:blood; D010010:Osteoclasts / Q000473:pathology; D010024:Osteoporosis / Q000150:complications*; D000071681:Tartrate-Resistant Acid Phosphatase; D016474:Weight-Bearing
chemical_list: D000596:Amino Acids; D007527:Isoenzymes; D015675:Osteocalcin; C036020:deoxypyridinoline; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase