Leinonen S (1) Med. Student, Suokas E (2) MSc (Eng.), Veiranto M (2) MSc (Eng.), Törmälä P (2) PhD, MD.Sci.h.c., Waris T (1) MD, PhD and Ashammakhi N (1) MD, PhD, FRCS.

1. Department of Surgery, Oulu University Hospital, P.O. Box 21, FIN-90029 OYS, Oulu, Finland
2. Institute of Biomaterials, Tampere University of Technology, P.O. Box 589, FIN-33101 Tampere, Finland.

Antibiotics- plus bioactive glass-containing bioabsorbable self-reinforced (SR) polylactide screws have been developed for antibacterial osteoconductive bone fixation. The aim of the present study was to test the pullout properties of these recently developed miniscrews. Ciprofloxacin- plus bioactive glass-containing SR-polylactide miniscrews (BC) were compared with miniscrews made of neat SR-polylactide (A), SR-polylactide with bioactive glass (B) and ciprofloxacin-containing SR-polylactide. BC miniscrews and their controls (A, B, C) (all of length 6.0 mm, core diameter 1.45 mm, thread diameter 2.0 mm) were applied to one pair of cadaveric fibulae. Pullout force was measured using a materials testing machine. We carried out 49-50 pullout tests for each implant type. The Mann-Whitney test and Student's t-test were used for statistical evaluation. The pullout force for BC miniscrews was 114.9 ± 34.0 (SD) N. Pullout forces for control miniscrews were 162.7 ± 37.8 N (A), 99.1 ± 16.2 N (B) and 142.9 ± 26.9 N (C). Differences between the four groups were statistically significant (p < 0.001). Ciprofloxacin- plus bioactive glass-containing polylactide miniscrews have good holding power to human cadaver fibulae. However, adding bioactive glass and ciprofloxacin components to neat SR-polylactide results in lower pullout values.