Dissolving magnesium hydroxide implants enhance mainly cancellous bone formation whereas degrading RS66 implants lead to prominent periosteal bone formation in rabbits.

Bone fractures often require internal fixation using plates or screws. Normally, these devices are made of permanent metals like titanium providing necessary strength and biocompatibility. However, they can also cause long-term complications and may require removal.

In vivo comparative study of tissue reaction to bare and antimicrobial polymer coated transcutaneous implants.

We coated transcutaneous implants made of titanium alloy Ti6Al4V with copolymer dimethyl (2-methacryloyloxy-ethyl) phosphonate and 4-vinylpyridine and investigated the tissue reaction with respect to its biocompatible and antimicrobial properties in vivo. We distinguished between clinically observable superficial inflammations and histologically detectable deep infections. The vinylpyridine moieties were transferred into cationic pyridinium groups by reaction with hexyl bromide.

Bioabsorbable interbody magnesium-polymer cage: degradation kinetics, biomechanical stiffness, and histological findings from an ovine cervical spine fusion model.

Study Design: An experimental study using a sheep cervical spine interbody fusion model.

Objective: First, to compare anterior cervical discectomy and fusion of an experimental bioabsorbable cage consisting of a magnesium alloy and a polymer (poly-ε-caprolactone, PCL) with an autologous tricortical iliac crest bone graft. Second, to determine the degradation kinetics of the cage, assess the 2 fusion devices for biomechanical stability, and determine their histological characteristics.

Preliminary results in anterior cervical discectomy and fusion with an experimental bioabsorbable cage - clinical and radiological findings in an ovine animal model.

Background: Bioabsorbable implants are not widely used in spine surgery. This study investigated the clinical and radiological findings after anterior cervical discectomy and fusion (ACDF) in an ovine animal model with an experimental bioabsorbable cage consisting of magnesium and polymer (poly-ϵ-caprolactone, PCL) in comparison to a tricortical bone graft as the gold standard procedure.

Materials And Methods: 24 full-grown sheep had ACDF of C3/4 and C5/6 with an experimental bioabsorbable implant (magnesium and PCL) in one level and an autologous tricortical bone graft in the second level.

Non-invasive pH determination adjacent to degradable biomaterials in vivo.

An appropriate pH level is an important prerequisite for the physiologal functioning of cells and tissues. Changes in the extracellular pH often lead to specific cellular reactions and an altered metabolism of cells and tissues influences the extracellular pH range. Thus a method to monitor the extracellular pH is a valuable tool to track specific tissue reactions.

In situ optical coherence tomography of percutaneous implant-tissue interfaces in a murine model.

Novel surface coatings of percutaneous implants need to be tested in biocompatibility studies. The use of animal models for testing usually involves numerous lethal biopsies for the analysis of the implant-tissue interface. In this study, optical coherence tomography (OCT) was used to monitor the reaction of the skin to a percutaneous implant in an animal model of hairless but immunocompetent mice.

Biocompatibility of rapidly solidified magnesium alloy RS66 as a temporary biodegradable metal.

Biodegradable magnesium-based alloys are very promising materials for temporary implants. However, the clinical use of magnesium-based alloys is often limited by rapid corrosion and by insufficient mechanical stability. Here we investigated RS66, a magnesium-based alloy with extraordinary physicochemical properties of high tensile strength combined with a high ductility and a homogeneous grain size of ~1 μm which was obtained by rapid solidification processing and reciprocal extrusion.

In vivo study of a biodegradable orthopedic screw (MgYREZr-alloy) in a rabbit model for up to 12 months.

Biodegradable magnesium-based implants are currently being developed for use in orthopedic applications. The aim of this study was to investigate the acute, subacute, and chronic local effects on bone tissue as well as the systemic reactions to a magnesium-based (MgYREZr-alloy) screw containing rare earth elements. The upper part of the screw was implanted into the marrow cavity of the left femora of 15 adult rabbits (New Zealand White), and animals were euthanized 1 week, 12 weeks, and 52 weeks postoperatively.

Fast escape of hydrogen from gas cavities around corroding magnesium implants.

Magnesium materials are of increasing interest in the development of biodegradable implants as they exhibit properties that make them promising candidates. However, the formation of gas cavities after implantation of magnesium alloys has been widely reported in the literature. The composition of the gas and the concentration of its components in these cavities are not known as only a few studies using non-specific techniques were done about 60 years ago.

In vivo fluorescence imaging of apoptosis during foreign body response.

Quantification of apoptotic tissues during inflammatory processes induced by biomaterials is challenging in vivo. Here we present a non-invasive method using a fluorescence imaging system which facilitates intermittent snap shots of the current state of local apoptotic tissue. For this purpose, apoptotic cells around two different subcutaneously implanted materials (titanium discs and copper-coated titanium discs) in hairless but immunocompetent mice were quantified after 4, 8 and 23 days of implantation.

Model based 3D segmentation and OCT image undistortion of percutaneous implants.

Optical Coherence Tomography (OCT) is a noninvasive imaging technique which is used here for in vivo biocompatibility studies of percutaneous implants. A prerequisite for a morphometric analysis of the OCT images is the correction of optical distortions caused by the index of refraction in the tissue. We propose a fully automatic approach for 3D segmentation of percutaneous implants using Markov random fields.

Designing the biocompatibility of biohybrids.

Biohybrid has been used as a fashionable term in scientific publications during the past years to describe a functional unit consisting of a bioactive and a structural component. The bioactive part of the biohybrid could consist of cells or bioactive molecules, while the structural part is of biological or non-biological origin. Biohybrids are currently used as implants and transplants in regenerative medicine or in vitro applications such as assays, biosensors or bioreactors.

Coating of titanium implants with copolymer supports bone regeneration: a comparative in vivo study in rabbits.

Purpose: In modern orthopedics aseptic loosening caused by the formation of micro-wear particles remains a problem for endoprosthetic joint replacements as revision surgery is necessary with corresponding costs and exertions by patients. This study is devoted to the question of how the osseous ingrowth of implants can be supported. It was investigated whether the developed copolymer, p-VBP-co-GMA, coated on the surface of the implants, supports bone healing.