Improvement of the bone-screw interface strength with hydroxyapatite-coated and titanium-coated AO/ASIF cortical screws

Antonio Moroni, Cesare Faldini, Michele Rocca, Susanna Stea, Sandro Giannini

Research output: Contribution to journalArticle

Abstract

Objective: To evaluate whether coating AO/ASIF screws with osteoconductive materials can improve bone-screw fixation. Design: Ninety-six AO/ASIF 4.5-millimeter cortical screws were divided into four paired groups and implanted in the femurs and tibiae of six sheep: Group A = standard stainless steel screws; Group B = stainless steel screws coated with highly crystalline hydroxyapatite; Group C = stainless steel screws coated with low crystalline hydroxyapatite; Group D = titanium screws coated with titanium. The screws were implanted according to the standard AO technique to an insertion torque of 2,000 Newton-millimeters. Sheep were killed at one, three, and twelve months after surgery. Main Outcome Measures: Extraction torque was measured on six screws from each group selected at random at time of each euthanization. Morphologic analysis of the bone-screw interface was performed on the remaining screws. Results: At each euthanization the extraction torque of Group A was lower than that of the other groups (p <0.0001). At three and twelve months the extraction torque of Group B was higher than that of Group D (p = 0.002). Morphologic results showed extensive bone-screw gap in Group A. Optimal osteointegration was observed in Groups B and C. Osteointegration of Group D was higher than that of Group A and lower than that of Groups B and C. Conclusions: It was demonstrated that AO/ASIF screws coated with osteoconductive materials achieve optimal fixation strength, even in the early phase. This fixation strength was significantly higher than that of the standard screws.

Original languageEnglish
Pages (from-to)257-263
Number of pages7
JournalJournal of Orthopaedic Trauma
Volume16
Issue number4
DOIs
Publication statusPublished - 2002

Keywords

  • AO/ASIF screws
  • Fixation
  • Hydroxyapatite
  • Stainless steel
  • Titanium

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Surgery
  • Physical Therapy, Sports Therapy and Rehabilitation

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