title: A novel device for resistance-free biomechanical testing of the metaphysis of long bones.
abstract: BACKGROUND
  Biomechanical testing is an essential component of bone research. In order to test the metaphyseal region of long bones, a typical location for the nowadays increasing field of osteoporotic bone changes, three-point bending and breaking test devices are suitable and widely used. The aim of our study was to increase the effectiveness of this method by using a newly developed ball-mounted platform design. This new design eliminates the negative effects of friction, present in previous studies, caused by the lengthening of the distal tibia along its diaphyseal axis while sliding over the surface of a fixed aluminum block.
  
  
  METHODS
  70 tibiae of 35 twelve week old, female Sprague Dawley rats were separated into two groups for a metaphyseal bending/breaking test. Group 1 was made up of the rat's right tibiae, Group 2 of the left tibiae. Group 1 was tested on a solid metal block according to previously established testing devices whereas Group 2 was tested on the newly designed device: the resistance-free gliding, ball-mounted platform. Stiffness (N/mm), yield Load (N), and failure Load (N) were registered. In the evaluation of both testing procedures, the results of the right and left tibiae were compared according to the rat they originated from.
  
  
  RESULTS
  Stiffness (S) showed highly significant differences (p = 0.002) with 202.25 ± 27.010 N/mm SD (Group 1) and 184.66 ± 35.875 N/mm SD (Group 2). Yield Load (yL) showed highly significant differences (p < 0.001) with 55.31 ± 13.074 N SD (Group1) and 37.17 ± 12.464 N SD (Group2). The mean failure Load (fL) did not differ significantly (p < 0.231) between Group 1: 81.34 ± 11.972 N SD and Group 2: 79.63 ± 10.345 N SD.
  
  
  CONCLUSIONS
  We therefore conclude that, used in the three-point bending/breaking test, the mobile, ball-mounted platform device is able to efficiently eliminate the influence of friction in terms of stiffness and yield load. Failure Load was not affected. We suggest that the new ball-mounted platform device, when compared to other existing techniques, generates more accurate test results when used in the three-point bending/breaking test of the metaphysis of long bones.
authors.forename: Gina Alicia
authors.initials: GA
authors.lastname: Mackert
authors.forename: Christoph
authors.initials: C
authors.lastname: Hirche
authors.forename: Helmut
authors.initials: H
authors.lastname: Harhaus
authors.forename: Dimitra
authors.initials: D
authors.lastname: Kotsougiani
authors.forename: Bernd
authors.initials: B
authors.lastname: Hoener
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kneser
authors.affiliation: Department for Hand-, Plastic- and Reconstructive Surgery - Burn Care Center - BG-Trauma Clinic Ludwigshafen, Department for Plastic Surgery of the University of Heidelberg, Ludwig-Guttmann-Str, 13, 67071 Ludwigshafen, Germany. leila.harhaus@bgu-ludwigshafen.de.
authors.forename: Leila
authors.initials: L
authors.lastname: Harhaus
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005260:Female; D017276:Friction; D010808:Physical Examination / Q000295:instrumentation* / Q000379:methods; D011237:Predictive Value of Tests; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D013314:Stress, Mechanical; D013977:Tibia / Q000502:physiology*