Study on the Optimization of Process Parameters for Absorbable Bone Plate with In-Mold Heat Treatment

Abstract:

Titanium alloy & stainless steel are major materials for bone fracture fixation such as bone screws and plates in today's medical devices. However, the fixation devices made of metal not only have the risk of metal ion release to cause human allergies, but they also need to be removed by a second surgical operation making pain and the risk of the patient’s wound infection after the bone fracture healing. The biodegradable Polylactic Acid (PLA) bone screws & bone plates have the great advantage of not needing a second operation, but their insufficient strengths make them not be widely used in the current bone fracture fixation. In the study, we use PLA as the matrix and in-mod heat treatment with induction coils to increase the strength of bone screw & plate by improving crystallinity of material. Regarding ASTM F2502 “Standard Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants”, we measure bending loads of test pieces before and after in-mold heat treatment, and obtain the optimized process parameters by Taguchi method that will increase the bend load of PLA bone plates by 34.82%. These optimal parameters are the injection speed of 80 mm/s, the melt temperature of 205 °C, the heat treatment temperature of 110 °C and heat treatment time of 20 min.

• Periodical: Solid State Phenomena (Volume 294)
• Pages: 71-76
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.294.71
• Online since: July 2019
• Authors: Wen Teng Wang*, Yu Chen Lin
• Keywords: Absorbable Bone-Plates, Biodegradable Thermoplastics, Crystallinity, In-Mold Heat Treatment

References

[1] L.-T. Lima, R. Aurasb, M. Rubinob, Processing technologies for poly (lactic acid),, Progress in Polymer Science 33 (2008), p.820–852.

[2] Surata, I. Wayan, I. G. Suriadi, and Krissanti Arnis. Mechanical properties of rice husks fiber reinforced polyester composites., International Journal of Materials, Mechanics and Manufacturing 2.2 (2014): 165-168.

DOI: 10.7763/ijmmm.2014.v2.121

[3] Yee, H. M., K. K. Choong, and MN Abdul Hadi. Sustainable development of tensioned fabric green structure in the form of Enneper., International Journal of Materials, Mechanics and Manufacturing 3.2 (2015): 125-128.

DOI: 10.7763/ijmmm.2015.v3.180

[4] K.Hamad , M. Kaseem , H.W. Yang , F. Deri , Y.G. Ko, Properties and medical applications of poly lactic acid: A review,, Express Polymer Letters 9.5 (2015), pp.435-455.

DOI: 10.3144/expresspolymlett.2015.42

[5] M. van der Elsta , A.R.A. Dijkemaa, C.P.A.T. Klein, P. Patkaa, H.J.Th.M. Haarmana, Tissue reaction on PLLA versus stainless steel interlocking nails for fracture fixation: An animal study,, Department of Traumatology, Free University Hospital, Amsterdam, The Netherlands, Biomaterials, Jan;16(2) (1995), pp.103-6.

DOI: 10.1016/0142-9612(95)98270-o

[6] Rong-Cheng Huang, Siang-An Wang, Chih-Liang Chang, Chih-Hau Chen Analysis of Energy Consumption in High Mold Temperature Injection Molding Process Technology,, Journal of Taiwan Energy, 2.1 (2016), pp.79-87.

[7] L. Nascimento, J. G. Perez, O. Santana, J. I. Velasco, M. L. Maspoch, E. F. Urquiza, Effect of the Recycling and Annealing on the Mechanical and Fracture Properties of Poly(Lactic Acid),, J Polym Environ, Vol. 18 (2010), p.654–660.

DOI: 10.1007/s10924-010-0229-5

[8] ASTM F2502, Stander Specification and Test Methods for Absorbable Plates and Screws for Internal Fixation Implants.

DOI: 10.1520/f2502

[9] ISO 5835:1991 Implants for surgery -- Metal bone screws with hexagonal drive connection, spherical under-surface of head, asymmetrical thread – Dimensions.

DOI: 10.3403/00249656u

[10] Yu-Chi Huang, Crystallinity and thermal degradation behavior of poly-L-lactide for dental/ orthopedic use,, master thesis, school of oral hygiene, Taipei Medical University (2001).