Estimation of local anisotropy of plexiform bone: Comparison between depth sensing micro-indentation and Reference Point Indentation

E. Dall'Ara, P. Grabowski, P. Zioupos, M. Viceconti

Research output: Contribution to journalArticlepeer-review


The recently developed Reference Point Indentation (RPI) allows the measurements of bone properties at the tissue level in vivo. The goal of this study was to compare the local anisotropic behaviour of bovine plexiform bone measured with depth sensing micro-indentation tests and with RPI. Fifteen plexiform bone specimens were extracted from a bovine femur and polished down to 0.05μm alumina paste for indentations along the axial, radial and circumferential directions (N=5 per group). Twenty-four micro-indentations (2.5μm in depth, 10% of them were excluded for testing problems) and four RPI-indentations (~50μm in depth) were performed on each sample. The local indentation modulus Eind was found to be highest for the axial direction (24.3±2.5GPa) compared to the one for the circumferential indentations (19% less stiff) and for the radial direction (30% less stiff). RPI measurements were also found to be dependent on indentation direction (pind: 0.47±0.03N/μm for axial, 11% lower for circumferential and 17% lower for radial. Significant correlations were found between US1 and Eind (p=0.001; R2=0.58), while no significant relationship was found between IDI and any of the micro-indentation measurements (p>0.157). In conclusion some of the RPI measurements can provide information about local anisotropy but IDI cannot. Moreover, there is a linear relationship between most local mechanical properties measured with RPI and with micro-indentations, but IDI does not correlate with any micro-indentation measurements.

Original languageEnglish
Pages (from-to)4073-4080
Number of pages8
JournalJournal of Biomechanics
Issue number15
Publication statusPublished - Nov 26 2015


  • Anisotropy
  • Bone
  • Micro-indentation
  • Plexiform
  • Reference Point Indentation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Rehabilitation
  • Biophysics
  • Biomedical Engineering


Dive into the research topics of 'Estimation of local anisotropy of plexiform bone: Comparison between depth sensing micro-indentation and Reference Point Indentation'. Together they form a unique fingerprint.

Cite this