Histological, Histomorphometrical, and Biomechanical Studies of Bone-Implanted Medical Devices: Hard Resin Embedding

Abstract

The growing incidence of degenerative musculoskeletal disorders as well as lifestyle changes has led to an increase in the surgical procedures involving implanted medical devices in orthopedics. When studying implant/tissue interface in hard materials (i.e., metals or dense plastics) and/or in large bone segments, the hard plastic embedding of the intact undecalcified tissue envelope with the implant in situ is needed. The aim of this work is to describe the advances and the possibilities of high-temperature methyl methacrylate (MMA) embedding for the histological, histomorphometrical, and biomechanical assessment of bone-implanted medical devices. Unlike routine techniques, undecalcified bone processing histology, using high-temperature MMA, requires a complex and precise sample processing methodology and the availability of sophisticated equipment and software for both sample preparation and analyses. MMA embedding permits the evaluation of biological responses to the presence of implanted medical devices without implant removal, allowing simultaneous qualitative and quantitative histological evaluation, both static and dynamic histomorphometry, and biomechanical analyses not possible with tissue decalcification. MMA embedding, despite being a demanding procedure, is still preferred to other kinds of resin-based embedding because of its peculiar characteristics, which allow the study of samples of big dimensions also implanted with hard materials without reducing the sample or removing the material. Dynamic measurements are allowed together with biomechanical investigations at the bone-biomaterial interface, obtaining a comprehensive and precise evaluation of the safety and effectiveness of medical devices for orthopedic regenerative, reconstructive, and reparative surgery.

Optimization for Bone Samples Embedded in Methyl Methacrylate

“…In agreement with our proposal, Maglio et al 27) , processed large bone samples, with or without metal implants, with or without bone substitute materials, at room temperature (RT) and the use of a chemical fume hood throughout the procedure. We use similar embedding protocols, although we selected dibutyl phthalate instead of nonylphenol ethoxylate used by them.…”

“…The pre-polymerized MMA base, used in most protocols, was employed to prevent the formation of bubbles. It also promotes sample orientation 5,13,19,24,27) . We observed a complete reduction of tissue sections detachment at the deplasticization process when we used the combination of acid etched glass and Haurpt's adhesive over slide glass.…”

Early osteoimmunomodulatory effects of magnesium–calcium–zinc alloys

“…Different 2 and 3D imaging technologies have been recently developed to study the bone-biomaterial interface in the body. [54][55][56][57] In this study, we used different histology, immunohistochemistry, histomorphometry, 3D micro computed tomography (µCT), and small-angle X-ray scattering (SAXS) analyses to evaluate the tissue responses to the Mg alloys. We hypothesized that the results obtained from both 2 and 3D imaging technologies would be comparable.…”

Influence of orthodontic mini-screw surface modifications on implant topography and osseointegration: an in- vivo study.

“…In the current study, histological, histochemical and histomorphometric analyses were used. Bernhardt et al (2012) 48 and Maglio et al (2020) 49 reported histological imaging as the gold standard for analyzing bone formation around metallic implants, as this method allows for the detection of inflammatory and cellular changes that cannot be detected by radiographic examination alone.…”