Replacement surgery of hip joint consists of the substitution of the joint with an implant able to recreate the articulation functionality. This article aims to review the current state of the art of the biomaterials used for hip implants. Hip implants can be realized with different combination of materials, such as metals, ceramics and polymers. In this review, we analyze, from international literature, the specific characteristics required for biomaterials used in hip joint arthroplasty, i.e., being biocompatible, resisting heavy stress, opposing low frictional forces to sliding and having a low wear rate. A commentary on the evolution and actual existing hip prostheses is proposed. We analyzed the scientific literature, collecting information on the material behavior and the human-body response to it. Particular attention has been given to the tribological behavior of the biomaterials, as friction and wear have been key aspects to improve as hip implants evolve. After more than 50 years of evolution, in term of designs and materials, the actual wear rate of the most common implants is low, allowing us to sensibly reduce the risk related to the widespread debris distribution in the human body.

https://www.mdpi.com/1996-1944/12/3/495/pdf

Materials for Hip Prostheses: A Review of Wear and Loading Considerations

Joint arthroplasty had revolutionized the outcome of orthopaedic surgery. Extensive and collaborative work of many innovator surgeons had led to the development of durable bearing surfaces, yet no single material is considered absolutely perfect. Generation of wear debris from any part of the prosthesis is unavoidable. Implant loosening secondary to osteolysis is the most common mode of failure of arthroplasty. Osteolysis is the resultant of complex contribution of the generated wear debris and the mechanical instability of the prosthetic components. Roughly speaking, all orthopedic biomaterials may induce a universal biologic host response to generated wear debris with little specific characteristics for each material; but some debris has been shown to be more cytotoxic than others. Prosthetic wear debris induces an extensive biological cascade of adverse cellular responses, where macrophages are the main cellular type involved in this hostile inflammatory process. Macrophages cause osteolysis indirectly by releasing numerous chemotactic inflammatory mediators, and directly by resorbing bone with their membrane microstructures. The bio-reactivity of wear particles depends on two major elements: particle characteristics (size, concentration and composition) and host characteristics. While any particle type may enhance hostile cellular reaction, cytological examination demonstrated that more than 70% of the debris burden is constituted of polyethylene particles. Comprehensive understanding of the intricate process of osteolysis is of utmost importance for future development of therapeutic modalities that may delay or prevent the disease progression.

https://jdc.jefferson.edu/cgi/viewcontent.cgi?article=1061&context=rothman_institute

Biological response to prosthetic debris

Recent alarming joint registry data highlighting increased revision rates has prompted further research into the area of metal-on-metal hip replacements and resurfacings. This review article examines the latest literature on the topic of adverse reactions to metal debris and summarises the most up-to-date guidelines on patient management. Adverse reactions to metal debris can cause significant damage to soft tissue and bone if not diagnosed early. Furthermore, not every patient with an adverse reaction to metal debris will be symptomatic. As such, clinicians must remain vigilant when assessing and investigating these patients in order to detect failing implants and initiate appropriate management.

/pdf/metal-on-metal-hip-arthroplasty-a-review-of-adverse-4qnodaodrr.pdf

Metal-on-Metal Hip Arthroplasty: A Review of Adverse Reactions and Patient Management.

Implant history extends more than 4000 years in antiquity, with biocompatible alloy implants extending over only 70 years. Over the past several decades, total hip and knee replacements of Ti-6Al-4V and Co-Cr-Mo alloys have exhibited post implantation life spans extending over 15 years; limited by infection, loosening, stress-shielding-related bone resorption and other mechanical failures. With the advent of additive manufacturing technologies, such as electron beam melting (EBM) over the past decade, personalized, patient-specific; porous (open-cellular) implant components can be manufactured, and the integration of chemical, biological and mechanical methods is able to optimize strategies for improving long-term clinical outcomes. This review outlines these strategies, which include enhanced osseointegration and vascularization prospects, and provides some evidence for, and examples of, clinical trials representative of millions of implant surgeries world-wide.

Open-cellular metal implant design and fabrication for biomechanical compatibility with bone using electron beam melting ☆

Background It has been established by previous studies that longer operative times can lead to higher rates of complications and poorer outcomes after total hip arthroplasty (THA). However, these studies were heterogeneous, examined limited complications, and have not provided a clear time after which complications increase. The aims of this study were to (1) assess whether longer operative time increases risk of complications within 30 days of THA, (2) investigate the relationship between operative time and various complications after THA, and (3) identify possible operative times beyond which complication rates increase. Methods The National Surgical Quality Improvement Project database was queried to identify 89,802 procedures that were included in the final analysis. The effect of operative time on complications within 30 days was evaluated using multivariate logistic regression models. Spline regression models were created to investigate the relationship between operative time and complications. Results Longer operative times were associated with higher risk of readmissions (P Conclusion While our findings cannot establish a clear cause and effect relation, they do suggest strong correlation between increased operative time and perioperative complications. Additionally, this study suggests an optimal time of approximately 80 minutes, as a goal for surgeons, that may be associated with less risk of complications following THA.

The Association Between Operative Time and Short-Term Complications in Total Hip Arthroplasty: An Analysis of 89,802 Surgeries.

Total hip arthroplasty (THA) has completely revolutionized the nature in which the arthritic hip is treated, and is considered to be one of the most successful orthopaedic interventions of its generation. With over 100 years of operative history, this review examines the progression of the operation from its origins, together with highlighting the materials and techniques that have contributed to its development. Knowledge of its history contributes to a greater understanding of THA, such as the reasons behind selection of prosthetic materials in certain patient groups, while demonstrating the importance of critically analyzing research to continually determine best operative practice. Finally, we describe current areas of research being undertaken to further advance techniques and improve outcomes.

Satya Prasad Biswas

Papers

Total Hip Arthroplasty – over 100 years of operative history