November/December AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 1 8 2 4 accommodate a patient’s natural anat- omy and the type of surgery being per- formed. The implants are widely used in many parts of the body where soft tissue and bone have been separat- ed, resulting in pain and loss of mo- tion. With an aging population and more active lifestyles, there is a grow- ing demand for these procedures. Low- er cost is an important consideration as well. Biomedical polymers offer advan- tages over metals such as titanium for these implantable devices. In addition to biocompatibility and chemical inert- ness, they have a modulus of elasticity that is closer to that of bone. PEEK and other polymers are also completely ra- diolucent, enabling surgeons to clear- ly see the bone/soft tissue interface on x-rays without the shadows and opacity of titanium. RôG (pronounced Rogue) Sports Medicine Inc., based in Illinois, has re- ceived 510(k) clearance from the U.S. Food & Drug Administration for its RôG Suture Anchor made of Zeniva poly- etheretherketone (PEEK) resin from Solvay Advanced Polymers [15-17] . This biomaterial, used as a reference in this case study, has a modulus very close to that of bone plus excellent toughness and fatigue resistance. These suture anchors are made from 6-mm-diam- eter PEEK rod stock and are threaded to screw into bone, thus securing the soft tissue to the prepared bone sur- face so that the soft tissue and bone reunite. Here, five polymers meet the constraints that were used and perform well in the objective of minimizing cost. They do, however, have slightly lower values than PEEK for the mechanical parameters used in this study. The values are roughly 30% less than those of PEEK, and it must be confirmed that this will not impede performance in the application. As a comparison, these values are still high- er than the ABS used for LEGO blocks and other sturdy toys. The values used in the constraints in this case study are chosen to be realistic but do not reflect actual test data requirements. CONCLUSIONS There is much to think about when choosing materials for biological appli- cations and especially when seeking to innovate in applications traditional- ly fulfilled by metals. Plastics and new options such as glass-ceramics are now entering the medical market. In ex- ploring these ideas, whether for edu- cational purposes as in the use of CES EduPack resources discussed here, or in industry, it is important to have the right materials data and tools to sup- port a systematic investigation. ~AM&P For more information: Dr. Claes Fredriksson, senior materials educa- tion consultant, Granta Design, Rustat House, 62 Clifton Rd., Cambridge, UK, CB1 7EG, +44 (0)1223 218000 , educa- tion.team@grantadesign.com References 1. Q.Z. Chen, I.D. Thompson, and A.R. Boccaccini, 45S5 Bioglass-Derived Glass-Ceramic Scaffolds for Bone Tissue Engineering, Biomaterials, 27, p 2414-2425, 2006. 2. F. Bloisi, et al., Matrix-Assisted Pulsed Laser Thin Film Deposition by Using Nd:YAG Laser, J. Nanomater., 2012. 10.1155/2012/395436. 3. HCL Technologies, An Overview of the Plastic Material Selection Process for Medical Devices, February 2013. http://www.hcltech.com/white-papers. 4. For example, see data record on NAS 30 (Styrolution) in the prospector database of the polymer database of CES EduPack. 5. A. Ohlin and L. Linder, Biocom- patibilty of Polyoxymethylene [Delrin] in Bone, Biomaterials, Vol 14, Issue 4, p 285-289, 1993. 6. For example, see data record on POM (copolymer) in the bioengineering level 3 database of CES EduPack. 7. For example, see data on poly- (oxymethylene), copolymer (POM-C) in the ASM Medical Materials Database. 8. K. Rezwan, et al., Biodegradable and Bioactive Porous Polymer/Inor- ganic Composite Scaffolds for Bone Tissue Engineering, Biomaterials, Vol 27, 2006. 9. K. Pielichowska, A. Szczygielska, and E. Spasowka, Preparation and Characterization of Polyoxymethylene- Copolymer/Hydroxyapatite Nanocom- posites for Long-Term Bone Implants, Polym. Adv. Technol., Vol 23, Issue 8, p 1141-1150, 2012. 10. For example, see data on poly- (lactic acid) (PLA) in the ASM Medical Materials Database. 11. A.R. Boccaccini, et al., Degradable and Bioactive Synthetic Composite Scaffolds for Bone Tissue Engineering, [N. Eliaz, book author], Degradation on Implant Materials, p 110-13, Springer, 2011. 12. D.W. Sommerfeldt and C.T. Rubin, Biology of Bone andHow it Orchestrates the Form and Function of the Skeleton, Eur. Spine J, Vol 10, suppl 2, p S86-S95, 2001. 13. For example, see data on poly(lac- tic acid)/hydroxyapatite (HAPLA) in the ASM Medical Materials Database. 14. Smith-Nephew, TWINFIX◊ Ultra HA Suture Anchor Enhancement of Biocompatibility. https://www. smithnephew.com/documents/nl- twinfix-ultra-ha-whitepaper.pdf, Dec. 7, 2015. 15. J.A. Grant, et al., Relationship Between Implant Use, Operative Time, and Costs Associated with Distal Biceps Tendon Reattachment, Orthopedics, Vol 35, Issue 11, e1618-e1624, 2012. 16. RoG Sports Medicine Inc., http:// www.buyrog.com, Dec. 7, 2015. 17. Solvay, Zeniva PEEKbiomaterial de- scription, http://www.solvay.com/en/ marketsand-products/featured-prod- ucts/solviva.html, Dec. 7, 2015. RôG suture anchor made of Zeniva PEEK resin from Solvay Advanced Polymers.