Biomaterials as Implants in the Orthopedic Field for Regenerative Medicine: Metal versus Synthetic Polymers

Abstract

Patients suffering bone fractures in different parts of the body require implants that will enable similar function to that of the natural bone that they are replacing. Joint diseases (rheumatoid arthritis and osteoarthritis) also require surgical intervention with implants such as hip and knee joint replacement. Biomaterial implants are utilized to fix fractures or replace parts of the body. For the majority of these implant cases, either metal or polymer biomaterials are chosen in order to have a similar functional capacity to the original bone material. The biomaterials that are employed most often for implants of bone fracture are metals such as stainless steel and titanium, and polymers such as polyethene and polyetheretherketone (PEEK). This review compared metallic and synthetic polymer implant biomaterials that can be employed to secure load-bearing bone fractures due to their ability to withstand the mechanical stresses and strains of the body, with a focus on their classification, properties, and application.

Radiopacity Enhancements in Polymeric Implant Biomaterials: A Comprehensive Literature Review

“…Bioresorbable stents were developed as an alternative to metallic stents, which often exhibited problems such as restenosis, fractures, and a need for additional surgical removal procedures. ,, Bioresorbable stents are typically made from synthetic biodegradable polymers, with PLLA being the most common choice due to its biodegradability and biocompatibility. , Researchers initially incorporated radiopaque markers made of dense metals such as tantalum, gold, or platinum at the proximal and distal ends of stents to enable their visibility during medical imaging. ,,, However, these markers offered only partial visibility of the implant, which was insufficient in monitoring the stent in vivo . Moreover, there were concerns about metal pieces remaining in the body after resorption of the stent …”

“…They can either be permanent, where their intended duration spans years, or temporary, where they are naturally biodegraded in vivo or removed upon healing . These polymers serve diverse functions, such as to restore the normal function of joints in arthroplasty, as drug delivery systems, or to provide physical and structural support to vascular systems. − Polymers possess desirable characteristics such as biocompatibility, flexibility, corrosion resistance, ease of production, and various mechanical, physical, and chemical properties, which are considered beneficial depending on the intended application . Additionally, their properties can easily be modified to satisfy a wide range of requirements. ,− …”

“…Commonly used synthetic polymers in medical implants include polyethylene (PE), mainly comprised of ultra high molecular weight PE (UHMWPE), polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), poly­(methyl methacrylate) (PMMA), polyurethane (PU), poly­(lactic acid) (PLA), poly­( l -lactic acid) (PLLA), poly­(glycolic acid) (PGA), poly­(lactic-co-glycolic acid) (PLGA), and polypropylene (PP) . These polymers have found application in dental, orthopedic, vascular systems, and tissue engineering contexts. , …”

Biopolymer‐based coatings for anti‐corrosion of Ti‐alloys used in biomedical applications: A review

“…A PHA, for example, is a polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), or a copolymer. Among the most extensively studied and well‐known PHAs is PHB 102–104 …”

An Advanced Human Bone Tissue Culture Model for the Assessment of Implant Osteointegration In Vitro

“…The evaluation for the most promising materials, which can blend the necessary mechanical and biological features, has been boosted, especially for the latter condition. Nowadays, the most used implantable devices are metallic, polymeric, or ceramic materials, each showing different characteristics and whose efficiency can vary according to the implantation sites [3]. Ceramic materials (e.g., hydroxyapatite and tricalcium phosphate) can be inert or bioactive, are highly biocompatible, and are easily shaped according to the morphology most suitable for their application, despite being less mechanically performing.…”