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.

Pull-Out Strength of Multifunctional Bioabsorbable Ciprofloxacin-Releasing Polylactide-Polyglycolide 80/20 Tacks

“…10 In an earlier study, PLGA tacks had similar or slightly better pull-out strength than the screws of same size (statistically insignificant difference, P = 0.69). 12 In another earlier study, ciprofloxacin-containing SR-PLGA screws had lower pull-out strength than plain SR-PLGA screws because adding of any drug may compromise the strength of the bioabsorbable material. 19 In scanning electron microscope (SEM) micrographs, fractures with axial direction were seen in the fibrillar striplike microstructure of plain SR-PLGA screw threads.…”

“…Also, in our earlier pull-out studies, the most common reason for failure with BioSorbPDX (SR-PLGA 80/20) tacks and SR-P(L/D)LA 70/30 tacks was barb breakage. 8,12 With screws, the most common reason for failure in pull-out tests was thread breakage with BioSorbPDX (SR-PLGA 80/20) screws and stem splitting with Lactosorb (PLGA 82L/18G) screws (LactoSorb, Warsaw, IN). 12 With ciprofloxacin-containing SR-PLGA 80/20 screws, the most common cause of failure was breakage of the screw shaft.…”

“…8,12 With screws, the most common reason for failure in pull-out tests was thread breakage with BioSorbPDX (SR-PLGA 80/20) screws and stem splitting with Lactosorb (PLGA 82L/18G) screws (LactoSorb, Warsaw, IN). 12 With ciprofloxacin-containing SR-PLGA 80/20 screws, the most common cause of failure was breakage of the screw shaft. 19 In that study also with plain SR-PLGA 80/20 screws, the most common cause of failure was screw-shaft breakage, but nearly as common cause was breakage of threads.…”

“…The tacks used in this study were developed and manufactured by Conmed Linvatec Biomaterials Ltd. A tackapplicator gun was used in this study for rapid insertion of tacks (Conmed Linvatec Biomaterials Ltd). For more details of the tackapplicator gun, see Tiainen et al 12 …”

“…The pull-out forces of such tacks were found to be comparable to screws of similar size in a previous study. 12 Bone infection (osteomyelitis) may complicate any surgical procedure or trauma. This serious problem may progress to a chronic osteomyelitis with its problematic and costly complications.…”