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Synthetic Bioresorbables: Industry Evolution from PLLA to New Formulas

By Robert A. Poggie, Ph.D.

Bioresorbable synthetic polymers were first introduced as medical devices in the late 1960s for sutures made of glycolic and lactic acid-based polymers. They continue to have broad applications in orthopaedic devices and as a component in bioresorbable biocomposites, drug delivery, cardiovascular applications and regenerative medicine. Further, current research and investments indicate a future where new bioresorbables will replace the current materials in orthopaedics.

The basis for developing bioresorbable devices was to eliminate the need for re-operation (e.g. sutures, bone screws and plates), eliminate stress shielding and enable normal regeneration of tissue, improve imaging capability and improve ease of revision.1,2 The early research of bioresorbable polymers led to the definitions of bioresorption in the context of degradation of polymers in vivo, and importantly, the degradation of products being safely metabolized and resorbed within the body while not eliciting an adverse reaction, and causing minimum consequences to the patient.

David F. Williams, Ph.D., Professor at the Institute for Regenerative Medicine at Wake Forest University, is considered one of the world’s leading authorities on biomaterials. Professor Williams has defined bioresorption as “the process of removal by cellular activity and/or dissolution of a material in a biological system.” The foremost performance requirement is biocompatibility, defined as “the ability of a biomaterial to perform its desired function with respect to a medical therapy, without eliciting any undesirable local or systemic effects in the recipient or beneficiary of that therapy, but generating the most appropriate beneficial cellular or tissue response in that specific situation, and optimizing the clinically relevant performance of that therapy.” The criteria for the ideal bioresorbable polymer is defined as: “does not evoke an inflammatory/toxic response, disproportionate to its beneficial effect; is metabolized in the body after fulfilling its purpose leaving no trace; is easily processed into the final product form; has acceptable shelf life; and is easily sterilized.”2

Read more at BONEZONE about the industry's transition away from Poly-L-lactic acid (PLLA)-type resorbable polymers to updated and novel resorbable biomaterials that are designed to perform better clinically.