Statistical distribution of micro and macro pores in acrylic bone cement- effect of amount of antibiotic content

Mahsa Alimohammadi; Hassan Mirzabozorg; Farzam Farahmand; Sunjung Kim; Caroline Baril; Heidi-Lynn Ploeg

doi:10.1016/j.jmbbm.2023.106297

Statistical distribution of micro and macro pores in acrylic bone cement- effect of amount of antibiotic content

J Mech Behav Biomed Mater. 2024 Feb:150:106297. doi: 10.1016/j.jmbbm.2023.106297. Epub 2023 Dec 8.

Authors

Mahsa Alimohammadi¹, Hassan Mirzabozorg², Farzam Farahmand³, Sunjung Kim⁴, Caroline Baril⁵, Heidi-Lynn Ploeg⁶

Affiliations

¹ Civil Engineering Department, KN Toosi University of Technology, Tehran, Iran; Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada.
² Civil Engineering Department, KN Toosi University of Technology, Tehran, Iran.
³ Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran.
⁴ Department of Orthopaedic Surgery, University of Illinois Chicago, Chicago, IL, USA.
⁵ Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada.
⁶ Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada. Electronic address: heidi.ploeg@queensu.ca.

PMID: 38100980
DOI: 10.1016/j.jmbbm.2023.106297

Abstract

Aseptic loosening due to mechanical failure of bone cement is considered to be a leading cause of revision of joint replacement systems. Detailed quantified information on the number, size and distribution pattern of pores can help to obtain a deeper understanding of the bone cement's fatigue behavior. The objective of this study was to provide statistical descriptions for the pore distribution characteristics of laboratory bone cement specimens with different amounts of antibiotic contents. For four groups of bone cement (Palacos) specimens, containing 0.3, 0.6, 1.2 and 2.4 wt/wt% of telavancin antibiotic, seven samples per group were micro computed tomography scanned (38.97 μm voxel size). The images were first preprocessed in Mimics and then analyzed in Dragonfly, with the level of threshold being set such that single-pixel pores become visible. The normalized pore volume data of the specimens were then used to extract the logarithmic histograms of the pore densities for antibiotic groups, as well as their three-parameter Weibull probability density functions. Statistical comparison of the pore distribution data of the antibiotic groups using the Mann-Whitney non-parametric test revealed a significantly larger porosity (p < 0.05) in groups with larger added antibiotic contents (2.4 and 0.6 wt/wt% vs 0.3 wt/wt%). Further analysis revealed that this effect was associated with the significantly larger frequency of micropores of 0.1-0.5 mm diameter (p < 0.05) in groups with larger antibiotic content (2.4 wt/wt% vs and 0.6 and 0.3 wt/wt%), implying that the elution of the added antibiotic produces micropores in this diameter range mainly. Based on this observation and the fatigue test results in the literature, it was suggested that micropore clusters have a detrimental effect on the mechanical properties of bone cement and play a major role in initiating fatigue cracks in highly antibiotic added specimens.

Keywords: Dragonfly; Histogram; Micro-CT; Palacos bone cement; Telavancin antibiotic; Three-parameter weibull distribution.

MeSH terms

Animals
Anti-Bacterial Agents
Bone Cements
Odonata*
Polymethyl Methacrylate*
Statistical Distributions
X-Ray Microtomography

Substances

Polymethyl Methacrylate
Anti-Bacterial Agents
Bone Cements