Biodegradable Bone Adhesives

Biodegradable bone adhesives are materials that induce complete bone regeneration and disappear as soon as the bone recovers, since they are gradually self-degrading in the body. Biodegradable adhesives thus serve as an alternative to conventional adhesives and have the advantage of not being necessary to remove once the fracture has healed. They are used in orthopaedic surgery mostly for the fixation of fractures. 

Widely used biodegradable materials as bone adhesives include polyglycolic acid (PGA), poly-L- lactic acid (PLLA), poly- DL-lactic acid (PDLLA), PGA/trimethylenecarbonate copolymers (PGA/TMC), poly-p-dioxanone (PDS) and poly-beta-hydroxybutyric acid (PBHBA). Research studies reveal that that they are safe for the majority of ankle fractures, but not suitable for comminuted and unstable fractures. 

Pain-point:

Most bone adhesives being used now are cements with minimal adhesive properties, which bond surfaces together by interlocking into pores and imperfections in the surfaces of the underlying bone.

For example, substances such as Plaster of Paris are injectable and provide the elements required for the inorganic component of bone, however, their setting characteristics are difficult to control particularly in an aqueous environment and their mechanical properties are far from ideal.

How is it solved?

Developing an ideal adhesive for bone repair is a difficult but potentially highly rewarding challenge requiring expertise from several scientific disciplines. A good bone adhesive should be able to work in the wet environment inside the body, must be setting quick with high strength (i.e., the capability to reabsorb over time and transition the wound to natural healed bone without a loss in strength).

Superglue (cyanoacrylate) is now routinely used in medical clinics to glue outer skin (under trade names like LiquiBand and Dermabond) because of the properties of quick setting and high strength. However they lack to work in the wet environment inside the body. 

Hence there is a need for a bioreabsorbable bone adhesive that can exhibit good biocompatibility and its degradation will not interfere with physiological fracture healing. 

End Users 

The main target of these products would be on the medical sector – Surgeons and Nurses. 

Market Size and growth  

The valuation of the orthopaedic biomaterials (orthopaedic biomaterials doesn’t mean bone adhesives. It mainly is nano-hydroxy appetites, osteoclast and osteoblast inducers) segment in 2009 was around $7.4 billion, representing over 17% of the orthopaedic total. At a growth rate of 13% per year, which is more than double the rate for the overall orthopaedics market, biomaterials segment will achieve a value of $9.4 billion by 2011. 

Growth in the U.S. market is expected to be somewhat faster than in Europe and significantly greater than in the developing world, partly because new biomaterials are relatively expensive and their uptake is related, in general terms, to GDP. Overall, the U.S. market for orthopaedic biomaterials is expected to grow by approximately 12% per annum over the next five years.

Researchers at CSIRO Molecular Science developed a biodegradable polymer that can be used in the human body. Not only is it biodegradable and biocompatible, it can be formulated as an injectable gel which cures in-situ or on-demand by promoting tissue growth. The polymer's rate of degradation can also be controlled.

At present, Polyethyleneglycol (PEG) based absorbable polymers serve as the premiere solution to advanced techniques in dura-sealant essentially replacing the “off-label” use fibrin glue for brain and spinal surgery. The same technology lends itself to multiple indications.

How far from commercialization?   

There has been a growing interest in the use of such adhesives in all fields of medicine in recent years. The wish of trauma surgeons and orthopaedic for alternatives to osteosynthesis is reflected in the development of a variety of surrogates of biological or synthetic origin. Despite a longstanding history of research in this field, a clinically applicable alternative in the field of bone gluing has not yet been found. 

A research in 2009 on rabbits indicates that biodegradable beta-Tri-Calciumphosphate (beta-TCP, Cerasorb) can be used as a biodegradable glue to fix broken bones. The sad part is that, this research has been proved in Rabbits. Further research on using beta-TCP on humans can be carried out. 

Additionaly, a researcher from the University of Utah has mimicked the glue of a special water-borne worm called Sandcastle worm to ‘stick together’ bones. As various superglues were found to be ineffective in a wet environment, this discovery has created a stir among surgeons. 

The key to the sandcastle worm's glue formulation is its use of coacervates—spherical droplets measured in microns (micrometers)—that encapsulate the glue in a shell of lipids (waxy molecules that repel water). So far, the sandcastle worm's glue has passed the three tests—strength, quickly sets, works underwater—but a fourth goal for commercialization is making it biodegradable, which they plan to tackle next. 

Another such adhesive can be reproduced from Mussels. The glue that Mussels use to stick to rocks can be used in surgery to stick bones and close wounds! Using this super glue would cause quicker healing, less pain and less scarring.

Competition Scenario: 

Adherion, a company partially owned by UMass Lowell, makes a biodegradable bone adhesive system based on a BPRC patent.

Polymerco Pty Ltd. was established by CSIRO and Xceed Biotechnology to develop this revolutionary new biodegradable polymer technology for medical device applications.

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