A citric acid-based hydroxyapatite composite for orthopedic implants

Hongjin Qiu, Jian Yang, Pradeep Kodali, Jason Koh, Guillermo A. Ameer

Research output: Contribution to journalArticlepeer-review

190 Scopus citations


We describe a novel approach to process bioceramic microparticles and poly(diol citrates) into bioceramic-elastomer composites for potential use in orthopedic surgery. The composite consists of the biodegradable elastomer poly(1,8-octanediol-citrate) (POC) and the bioceramic hydroxyapatite (HA). The objective of this work was to characterize POC-HA composites and assess the feasibility of fabricating tissue fixation devices using machining and molding techniques. The mechanical properties of POC-HA composites with HA (40, 50, 60, 65 wt.%) were within the range of values reported for tissue fixation devices (for POC-HA 65 wt.%, Sb=41.4±3.1, Eb=501.7±40.3, Sc=74.6±9.0, Ec=448.8±27.0, St=9.7±2.3, Et=334.8±73.5, Ss=27.7±2.4, Ts=27.3±4.9, all values in MPa). At 20 weeks, the weight loss of POC-HA composites ranged between 8 and 12 wt.%, with 65 wt.% HA composites degrading the slowest. Exposure of POC-HA to simulated body fluid resulted in extensive mineralization in the form of calcium phosphate with Ca/P of 1.5-1.7 similar to bone. POC-HA supported osteoblast adhesion in vitro and histology results from POC-HA samples that were implanted in rabbit knees for 6 weeks suggest that the composite is biocompatible. Synthesis of POC-HA is easy and inexpensive, does not involve harsh solvents or initiators, and the mechanical properties of POC-HA with 65 wt.% HA are suitable for the fabrication of potentially osteoconductive bone screws.

Original languageEnglish (US)
Pages (from-to)5845-5854
Number of pages10
Issue number34
StatePublished - Dec 2006

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Bioengineering
  • Ceramics and Composites
  • Biomaterials
  • Mechanics of Materials


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