Biomaterials are currently being used in many medical fields including the production of implants, tissue engineering, orthopedic and prosthetic aids, and drug delivery systems among many others. The use of biomaterials is progressively associated with additive manufacturing (AM) of different medical devices and aids.
Biomaterials use in medicine is significant not only in terms of their biocompatibility and direct effect on the human body, but also in terms of their biodegradability, processability, and environmental non-toxicity during their manufacture or after-use processing. Polylactic acid (PLA) bioplastics tend to be suitable biomaterials to be used with an AM system in a variety of medical applications.

What are orthopedic biomaterials?

The nature of biomaterials, their structural structures, and their properties, and also the implications of their contact with the human body's soft and hard tissues, blood, and intra- and extracellular fluids, is a critical aspect for surgeons.

The field of orthopedics has benefited from the continued efforts of many orthopedic surgeons, laboratories for experimental surgery, and research centers, and research work at universities, societies, scientific organizations, and several interdisciplinary associations. Nonetheless, in the production of new biomaterials that will increase the long-term quality of clinical outcomes in orthopedic surgery, many obstacles remain to be addressed.

Types of orthopedic biomaterials:

• Polymers

Polymers are organic materials forming large chains consisting of various repeating units. Polymers are commonly used in parts of joint replacement. Ultra-high molecular weight polyethylene (UHMWPE), thermoplastic polyether ether ketone (PEEK), acrylic bone cement, and bioabsorbable are currently the most commonly used polymers for joint replacements.

• Composites

To obtain properties that enhance each of the components, composite biomaterials are created with filler (reinforcement) in addition to a matrix material. It means that there may be many processes in composite materials. Also, many matrix materials with different types of fillers can be mixed. Polymers comprising fillers of particulate are known as particulate composites. Fiber-reinforced polymers and polymethyl methacrylate (PMMA) aggregates are the polymers considered while designing orthopedic devices.

• Metal

Comprehensive research focuses on the improvisation of a metallic biomaterial's mechanical and biological performance for improved bone-implant performance. Metals have been used in medical treatments for several decades. During the 17th century, metallic implants were observed to be used in various cases. The metal screw implant was first used in the 18th century.

Most of the periodic table elements are metals. Metallic biomaterials are mainly used in load-bearing systems including hip and knee prostheses and for fixing internal and external fractures of the bone. Knowing the physical and chemical properties of the various metallic materials used in orthopedic surgery and their interaction with the human body's host tissue is quite essential.

Where are orthopedic biomaterials used?

1. Orthobiologics

Orthobiologics is a particular type of biomaterial. Such materials are used by orthopedic and dental surgeons to facilitate bone and tissue healing. Bioactive glass, bone cement, bone void fillers, and dura membranes are examples of orthobiological products that are commonly used. The explosive growth of orthopedic biologics in recent times shows just how strong and profitable the integration of the biotechnology and medical device markets can be.

2. Implants

Orthopedic implants, like those made from stainless steel, cobalt-based alloys, and titanium (Ti) alloys, are widely used to stabilize, protect, strengthen, replace or regenerate damaged musculoskeletal tissues in millions of patients with bone trauma, both anatomically and functionally. Magnesium (Mg) and alloys based on magnesium are the new generations of degradable implant materials that have gained a great deal of attention over the past 10 years. Recent findings indicate that alloying magnesium with aluminum (Al), calcium (Ca), zinc (Zn), zirconium (Zr), yttrium (Y) and elements of rare earth can dramatically improve its resistance to corrosion and mechanical strength.

3. Joint replacements

In the human body, prosthetic devices are inserted to replace the injured joint. This is done to alleviate discomfort and regain its normal function. It is well known that femoral stem joint replacements have a mean useful life that is closely linked to wearing particles, among other factors. Titanium-based alloys, cobalt-chromium alloys, ceramics, and cross-linked ultra-high molecular weight polyethylene are the biomaterials used during total knee replacements.

The bottom line

The next generation's increased demand for orthopedic biomaterials, specifically to meet the need for a targeted orthopedic procedure, has strengthened the global reach of the market. Orthopedic injuries and degenerative conditions are unfulfilled clinical needs and are constantly increasing and straining healthcare systems throughout the world.

Advanced biomaterial-based tissue engineering methodologies put forward the notion that scaffolds can be used to repair and restore lost tissue function. This also provides mechanical resilience, a means of protecting therapeutic cargo (e.g. cells, biologics), which will trigger local endogenous repair mechanisms and a template for the neotissue to be formed.

The future of biomaterial design will depend on the advancement of bioresorbable implant materials that degrade in vivo after complete and safe tissue growth. This has to happen without producing harmful degradation products at the targeted anatomic site. Permanent biomaterials presently used in mandibular reconstruction frequently result in effects of pressure shielding due to mismatch between bone and implant in Young's modulus values, resulting in loosening of implants.

The biomedical community has recently explored magnesium (Mg)-based materials as being the potential materials for mandibular reconstruction. The reason being, they exhibit favorable mechanical properties, sufficient biocompatibility, and degradability.