biabsorable materialA bioabsorbable polymer is a substance similar to some plastics. They have been found to break down in the human body while becoming fully absorbed. They are a chemical compound used in orthopedic implant devices that eventually completely dissolve.

Bioabsorbable polymers are suitable materials for making a prosthetic. They can be engineered to dissolve at the same rate as new bones grow. The polymers have also proved to be more durable and elastic than a stiff metal alloy bone prosthetic. These have been known to often interfere with bone re-growth.

Injection molding processes are known for producing medical devices that involve the use of bioabsorbable polymers, which always become absorbed by the body over time. They are the viable alternative to metal components or more traditional polymers. They can even remain for controlled time periods.

When an absorbable device is inserted into a body - the need to remove it later is eliminated - saving cost, risk of infection and speed of healing. Injection molding processes easily utilize synthetic bioabsorbable polymers which are manufactured into many necessary shapes.

Emergent Polymer Technology Enhances Injection Molding


Injection molding specialists have begun working towards bioabsorbable polymers for expanded medical device manufacturing to replace metallic fracture-fixing devices and systems.

Some project that bioabsorbed polymers will perform vital body functions and then become dissolved. They generate no harmful debris and include polyesters, poly amino acids, polyanhydrides, polyortho-esters, polyurethanes and polycarbonates. They are MRI compatible.

Bioabsorbable polymers are prepared by copolymerization of monomers to modify and improve their properties as applications demand. Blending (mechanically mixing as opposed to copolymerization) the polymers can further expand their properties.

For example, blending poly (L-lactide) and poly (D-lactide) at a 1:1 ratio provides more strength and greater thermal and chemical stability than the individual polylactides.

Bio-Absorbable Polymers: 

New Designs for Drug-Delivery Technologies, Stents, Medical Devices

The copolymerization process means to engage a change similar to polymerization yet with unions of two or more differing monomers. Polymerization involves forming polymers - which is the combining of molecules forming a more complex result.

Monomers are molecules of low molecular weight. They react with other monomers to form a polymer. Basically, injection molding bioabsorbable polymers follows principals for molding conventional polymers although they are in a state of constant change as described by the word "biodegradable."

Once implanted - polymers serve to transfer responsibility to natural tissues in order to synch with the healing process. Drugs can be placed inside this polymer matrix for release at a rate controlled by the degradation of these materials.

Injection molding first transitions a polymer from a solid state to a semi-liquid state. By heating the material above a threshold temperature and reducing viscosity, the property of a fluid-resisting force tends to cause the fluid to flow upon turning it into a liquid - the polymer can then be injected into the cavity of a mold.

The process must then be reversed. Materials must cool and return to a solid state before removal from the mold. 

Absorbable polymers are used to make current non-absorbable medical devices absorbable. They provide drug-release from a product while allowing cellular in-growth into a product. Second removal procedures are rendered unnecessary. New products relying on bioresorbables primarily include cardiovascular applications.

Future bioabsorbables will be likely used for tissue-scaffolding. Cells would be seeded into the bioresorbable, then as the cells grow together - the biopolymer slowly melts away - leaving behind living tissue, only.

Bioresorbables are introduced as drug-delivery structures in new applications that need long residence times with long-term, slow-dose treatment. Similar to drug-eluting stent functions - bioresorbables are made to mimic the same release process, and are also reabsorbed after their intended useful life.

Bioabsorbable polymers are plastic-based materials that dissolve into compounds the body can safely absorb or eliminate.  Bioabsorbable polymers create flexibility, enhance creep-resistance and strength, while preserving the structural integrity of tissues until they heal.

Most Current Uses for Bioabsorbable Polymers

Evolution in this field is steady, and new applications are being discovered regularly. The most current applications of bioabsorbable polymers include:

  • Wound management
  • Orthopedics (fracture fixation plates, pins and screws, bone augmentation, nails (scaffolding)
  • Dental (Packing, dry socket treatment, scaffolding)
  • Surgical (Ligament repair, wound closure (sutures, suture anchors, skin staples, & adhesives), adhesion barriers, drug delivery, antineoplastic delivery, ligating clips, hemostasis clips, temporary RO markers)
  • Stents (vascular, coronary, biliary, ureteral, esophageal, etc.)
  • Tissue engineering (3-D structures, electro-spinning, molded, extruded Vascular graft with scaffolding, Bowel anastomosis and ureteral anastomosis, Guided nerve regeneration, Percutaneous devices with limited ingrowth, Tissue engineering scaffolds, Vehicles for controlled drug and therapeutic agent delivery)
  • Controlled drug delivery                                                                                        

Stents and grafts are also possible along with 3D-porous scaffolds, films and coatings, injectable gels, microspheres, and shapes for drug-delivery.

Bioabsorbable polymers are FDA-approved for medical devices. They are tailored to customer specifications. Bioabsorbables are widely used for cardiovascular applications. Many of these applications are small, complex, 3D structures that can only be manufactured or created by using injection molding. 

If you would like more information on how Crescent Industries can help with your next project, please contact Kevin Allison at kallison@crescentind.com or 717-235-3844.

Topics: custom injection molding