Tiainen J, MD (1), Veiranto M, MSc (Eng.) (2),
Suokas E, Dr. Tech. (3), Törmälä P, PhD, Sci.h.c. (2), Waris T,
MD, PhD (4), Ninkovic M, MD, PhD (5), and Ashammakhi N, MD,
PhD, FRCSEd (1).
1. Department of Surgery, Oulu University Hospital, P.O.
Box 20, FIN-90029 Oulu, Finland.
2. Institute of Biomaterials, Tampere University of Technology, P.O. Box
589, FIN-33101 Tampere, Finland.
3. Bionx Implants Ltd., P.O. Box 3, FIN-33721 Tampere, Finland.
4. Department of Surgery, Tampere University Hospital and University of
Tampere, Tampere, Finland.
5. Department of Reconstructive Surgery, Innsbruck University Clinic,
Anichstraße 35, A-6020 Innsbruck, Austria.
Abstract
The aim of this study was to compare the pull-out forces of recently developed
bioabsorbable ciprofloxacin-containing and plain self-reinforced polylactide/polyglycolide
(SR-PLGA) miniscrews in human cadaver parietal bones. Parietal bone pieces
(c. 6 cm x 20 cm) were collected from five human male cadavers (44 to
75 years old). Fifty plain self-reinforced (SR-PLGA 80/20) miniscrews
(diameter 1.5 mm, length 4.0 mm) and fifty ciprofloxacin-containing SR-PLGA
(80/20) miniscrews (diameter 1.5 mm, length 4.0 mm) were used in this
study. The force needed to pull the screws from human parietal cadaver
bones was measured using a tensile strength testing machine. The screw
pull-out speed was 10 mm/min. Means and standard deviations (SDs) were
calculated and analyzed using Student's t-test (SPSS version 10.0 for
Windows). The pull-out forces of the ciprofloxacin-containing and plain
miniscrews were 66.8 ± 4.9 and 96.3 ± 9.3 N (significant difference, p<0.001),
respectively. The most common cause of failure was screw-shaft breakage
(60% in the case of ciprofloxacin-containing screws and 52% in the case
of plain SR-PLGA screws). Scanning electron microscopy (SEM) showed that
the fibrillar strip-like microstructure of plain SR-PLGA miniscrews turns
into a coarse uni-axial platelet-like morphology in antibiotic SR-PLGA
miniscrews as a result of the addition of ciprofloxacin. Ciprofloxacin-containing
SR-PLGA screws consequently have lower pull-out strength than corresponding
plain conventional SR-PLGA screws.
Keywords: Antibiotic, Bioabsorbable, Ciprofloxacin, Miniscrew,
SR-PLGA
