Biomaterials in spinal fixation. An experimental animal study to improve the performance

M. Rocca, M. Fini, T. Greggi, P. Parisini, A. Carpi, R. Giardino

Research output: Contribution to journalArticlepeer-review


Different pedicle screws were biomechanically and morphologically studied and compared through the use of an animal model to determine their efficacy and resistance in spinal fixation. The principal objective was to compare biomechanical and histomorphological aspects of HA-coated screws to uncoated ones. Fourty-eight cylindrical transpedicular self-tapping screws divided into three groups of sixteen each were employed; Group A: stainless steel screws; Group B: titanium screws; Group C: HA-coated titanium screws. The screws were implanted bilaterally and randomly into the L3, L4, and L5 pedicles of eight adult mongrel sheep. The final insertion torque was measured in all the implants. After one and four months, upon euthanization, four samples per group were extracted from the surrounding bone and the screw extraction torque was measured. The remaining samples were examined and processed for histological and histomorphological evaluations. No differences were observed at one month among the extraction torque of the three groups. After four months the only significance between insertion and extraction values was for the HA group, i.e. p=0.001. Comparing the extraction torque values of the three groups after four months of healing, the HA-coated group showed a greater than twofold increase (p

Original languageEnglish
Pages (from-to)824-830
Number of pages7
JournalInternational Journal of Artificial Organs
Issue number12
Publication statusPublished - 2000


  • Hydroxyapatite
  • Implant
  • Pedicle
  • Screw
  • Torque

ASJC Scopus subject areas

  • Biophysics


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