Comparison of the Pull-Out Forces of Bioabsorbable Polylactide/Glycolide Screws (Biosorb and Lactosorb) and Tacks: A Study on the Stability of Fixation in Human Cadaver Parietal Bones

Abstract

The aim of this study was to compare the pull-out forces of bioabsorbable polylactide/glycolide (PLGA) tacks and screws in human cadaver parietal bones. Parietal bone pieces (c. 6 cm x 20 cm) were collected from five human male cadavers (age range: 47-75 years). Forty-nine BioSorbPDX (self-reinforced [SR] PLGA 80/20) tacks (1.5-mm diameter, 4.0-mm length), 47 BioSorbPDX (SR-PLGA 80/20) screws (1.5-mm diameter, 4.0-mm length), and 46 LactoSorb (PLGA 82/18) screws (1.5-mm diameter, 4.0-mm length) were applied. The tacks were applied to drill holes using a special applicator gun (no tapping or tightening). The screws were applied to drill holes in the traditional way using tapping and tightening with a screwdriver. A tensile testing machine was used. All the implants were tested thus: the head of the implant was held by an aluminum jig, and the jig was pulled with wire until implant failure. The testing pull speed was 10 mm/min. Means and SDs were calculated, and the data were analyzed using ANOVA. The pull-out force of the tacks was 115.9 +/- 8.3 N, that of Lactosorb screws was 112.9 +/- 12.1 N, and that of Biosorb screws was 110.4 +/- 8.9 N (statistically insignificant difference between the three groups). The most common reason for failure in the case of tacks was barb breakage (55.1%); it was thread breakage in the case of BioSorb screws (66%) and stem split in the case of Lactosorb screws (56%). Tacks seem to have a similar, perhaps even a little better, holding power to cranial bone as screws and can hence be recommended for clinical application, as the procedure saves time and, consequently, costs.