Analysis of plastic deformation in cortical bone after insertion of coated and non-coated self-tapping orthopaedic screws

Abstract

Insertion of internal fracture fixation devices, such as screws, mechanically weakens the bone. Diamond-like carbon has outstanding tribology properties which may decrease the amount of damage in tissue. The purpose of this study was to investigate methods for quantification of cortical bone damage after orthopaedic bone screw insertion and to evaluate the effect of surface modification on tissue damage. In total, 48 stainless steel screws were inserted into cadaver bones. Half of the screws were coated with a smooth amorphous diamond coating. Geometrical data of the bones was determined by peripheral quantitative computed tomography. Thin sections of the bone samples were prepared after screw insertion, and histomorphometric evaluation of damage was performed on images obtained using light microscopy. Micro-computed tomography and scanning electron microscopy were also used to examine tissue damage. A positive correlation was found between tissue damage and the geometric properties of the bone. The age of the cadaver significantly affected the bone mineral density, as well as the damage perimeter and diameter of the screw hole. However, the expected positive effect of surface modification was probably obscured by large variations in the results and, thus, statistically significant differences were not found in this study. This can be explained by natural variability in bone tissue, which also made automated image analysis difficult.

Enhanced Bone Screw Fixation with Biodegradable Bone Cement in Osteoporotic Bone Model

“…Our further interests in this subject include comparison tests with several commercial or novel bone cements as well as fatigue tests at body temperature and in liquid to reveal the effect of cyclic loading. The use of animal or cadaveric bone as in previous studies (34,35) will be also considered.…”

Interfacial Sliding Properties of Bone Screw Materials and Their Effect on Screw Fixation Strength

“…Pullout strength for PMMA was significantly lower (P<0.05, 1-way ANOVA) than for Sawbones®. Pullout strength was not tested for cadaver bone due to histological sectioning of the samples required in our previous study (26).…”

Screw-Bone Interface Modelling in Locking Plate Fe Models

“…Excessively large strains and damage in host bone will encourage resorpsion and compromise holding strength. It is therefore desirable to limit the damage caused to the bone during screw insertion (Koistinen et al, 2011). Thread-forming screws were shown to cause the most damage during insertion in a study by Kuhn et al (1995).…”