Hypersensitivity to orthopaedic implant manifested as erythroderma: Timing of implant removal

Contact Dermatitis From Biomedical Devices, Implants, and Metals-Trouble From Within

Allergic contact dermatitis is characterized by its appearance of red, raised and infiltrated, scaling or scabbed skin and intense pruritus, and distinguished from irritant contact dermatitis by its specific immune process and histopathology. Many contact allergens are low-molecular- weight chemicals including metals such as nickel, cobalt, and chromium, preservatives, and adhesives. When such materials are used internally in biomedical devices, they are similarly capable of causing sensitization and an inflammatory response. Sometimes, the reaction remains internal, and presents as swelling, pain, stiffness, decreased range of motion, and internal itching around the implant. Such reactions may, in some cases, also extend to include a localized or, rarely, systemic contact dermatitis indicative of the same process. This review will present an overview of reported skin and local internal reactions to orthopedic implants, which are the largest category of implanted internal metal devices. Immune reactions to smaller categories of medical appliances include cardiac devices and vascular stents, neuromodulation devices, diabetic appliances, Nuss bar surgery for pectus excavatum, and dental and spinal implants. We will review the available diagnostic tools, the consensus on interpretation, and reported strategies for treatment.

Fatigue Crack Growth and Fracture of Internal Fixation Materials in In Vivo Environments-A Review

The development of crack patterns is a serious problem affecting the durability of orthopedic implants and the prognosis of patients. This issue has gained considerable attention in the medical community in recent years. This literature focuses on the five primary aspects relevant to the evaluation of the surface cracking patterns, i.e., inappropriate use, design flaws, inconsistent elastic modulus, allergic reaction, poor compatibility, and anti-corrosiveness. The hope is that increased understanding will open doors to optimize fabrication for biomedical applications. The latest technological issues and potential capabilities of implants that combine absorbable materials and shape memory alloys are also discussed. This article will act as a roadmap to be employed in the realm of orthopedic. Fatigue crack growth and the challenges associated with materials must be recognized to help make new implant technologies viable for wider clinical adoption. This review presents a summary of recent findings on the fatigue mechanisms and fracture of implant in the initial period after surgery. We propose solutions to common problems. The recognition of essential complications and technical problems related to various approaches and material choices while satisfying clinical requirements is crucial. Additional investigation will be needed to surmount these challenges and reduce the likelihood of fatigue crack growth after implantation.

Systemic Effects of Metals Released from Arthroplasty Implants – a Brief Summary

In recent years, increasing concern has been raised regarding potential systemic toxicity of metals released from arthroplasty implants. A lack of valid metal thresholds for human (organ) toxicity and the prospect of multi-decade survival of modern hip and knee replacements pose special challenges. Indeed, evidence of systemic effects of metals released from such implants is largely missing. Systemic cobalt exposure has repeatedly been associated with cardiotoxic and neurotoxic effects, and also with thyroid dysfunction. The toxic potential of chromium is considered less pronounced. Yet, in arthroplasty there is usually a co-exposure to chromium and cobalt which complicates evaluation of element-specific effects. Toxicity of titanium dioxide nanoparticles has been subject to debate among international regulatory authorities. Their wide use in a variety of products in everyday life, such as toothpaste, cosmetics and food colorants, hampers the assessment of an arthroplasty-induced systemic titanium exposure. To date there is no clear evidence for systemic complications due to titanium dioxide released from arthroplasty implants. Release of further metals such as tantalum, niobium, nickel, vanadium and zirconium from hip and knee replacement implants has been described occasionally, but systemic effects of respective long-term exposure scenarios are unknown. Generally, the characterization of all released metals regarding their chemical and physical specifications is critical for the evaluation of potential systemic risks. Systematic studies investigating the accumulation of metals relevant in arthroplasty in different organs/organ systems and the biological consequences of such accumulations are urgently needed.

Effect of thermomechanical treatment on the mechanical and microstructural evolution of a β-type Ti-40.7Zr-24.8Nb alloy

In this study, the microstructural evolution and mechanical properties of a newly developed Ti-40.7Zr–24.8Nb (TZN) alloy after different thermomechanical processes were examined. As-cast TZN alloy plates were solution-treated at 890 °C for 1 h, after which the thickness of the alloy plates was reduced by cold rolling at reduction ratios of 20%, 56%, 76%, and 86%. Stress-induced α” formation, {332} <113> β mechanical twinning, and kink band formation were observed in the cold-rolled TZN alloy samples. In the TZN sample after cold rolling at the 86% reduction ratio plus a recrystallization annealing at 890 °C for 1 h, the deformation products of a stress-induced α” phase, {332}<113> β mechanical twinning, and kink bands disappeared, resulting in a fine, equiaxed single β phase. The alloy samples exhibited elongation at rupture ranging from 7% to 20%, Young's modulus ranging from 63 to 72 GPa and tensile strength ranging from 753 to 1158 MPa. The TZN alloy sample after cold rolling and recrystallization annealing showed a yield strength of 803 MPa, a tensile strength of 848 MPa, an elongation at rupture of 20%, and an elastic admissible strain of 1.22%, along with the most ductile fractures during tensile testing.

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A newly developed Ti-40.7Zr–24.8Nb (TZN) alloy was thermomechanically processed.

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Deformation occurred via kink bands, mechanical twinning, and stress-induced α”.

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Cold rolling resulted in an increase in the tensile strength.

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Deformation products were disappeared after recrystallization annealing.

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TZN alloy can be considered as a promising candidate biomedical material.