RESEARCH ARTICLE


Evaluation of the Fatigue Performance and Degradability of Resorbable PLDLLA-TMC Osteofixations



Constantin Landes1, *, Alexander Ballon1, Shahram Ghanaati1, Daniel Ebel2, Dieter Ulrich2, Uwe Spohn3, Ute Heunemann3, Robert Sader1, Raimund Jaeger2
1 Oral, Craniomaxillofacial and Plastic Facial Surgery, The Center of Surgery, Goethe University Medical Centre, Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany
2 Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany
3 Fraunhofer Institute for Mechanics of Materials IWM, Biological and Biocompatible Materials – group, Fraunhofer-IWM, Walter-Hülse-Str. 1, 06120 Halle

Article Information


Identifiers and Pagination:

Year: 2013
Volume: 7
First Page: 133
Last Page: 146
Publisher ID: TOBEJ-7-133
DOI: 10.2174/1874120701307010133

Article History:

Received Date: 21/5/2013
Revision Received Date: 24/9/2013
Acceptance Date: 3/10/2013
Electronic publication date: 29 /11/2013
Collection year: 2013

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Creative Commons License
© Landes et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Oral, Craniomaxillofacial and Plastic Facial Surgery, Goethe University Medical Centre, Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany Tel: +49 69 6301 6859; Fax: +49 69 6301 5644; E-mail: constantinlandes@gmail.com


Abstract

The fatigue performance of explanted in-situ degraded osteofixations/osteosyntheses, fabricated from poly (70L-lactide-co-24DL-lactide-6-trimethylane-carbonate or PLDLLA-TMC) copolymer was compared to that of virgin products. The fatigue test was performed on 21 explants retrieved from 12 women and 6 men; 16-46 years by a custom-designed three-point bend apparatus using a staircase method and a specified failure criterion (an increase of the deflection of the specimen > 1 mm) with run-out designated as “no failure” after 150,000 loading cycles. While all the virgin products showed run-out at 38N, all of the specimens fabricated from explants failed at this load level. For the explant specimens, although there was a trend of decreased failure load with increased in-situ time, this decrease was pronounced after 4 months in-situ, however, not yet statistically significant, while a 6-month in-situ explant had significantly less failure load. Three and four month in-situ explants had highly significant differences in failure load between measurements close and distant to the osteotomy line: p=0.0017 (the region of maximum load in-situ). In the virgin products, there were only traces of melt joining and cooling, left from a stage in the manufacturing process. For the implants retrieved after 4.5 months in-situ, the fracture surfaces showed signs of degradation of the implants, possibly caused by hydrolysis, and for those retrieved after 9 months in-situ, there were cracks and pores. Thus, the morphological results are consistent with those obtained in the fatigue test. The present results suggest that resorbable osteofixations fabricated from PLDLLA-TMC are stable enough to allow loading of the healing bone and degrade reliably

Keywords: : Polylactic acid, resorbable osteosyntheses, resorbable osteofixation, PLLA, PLDLLA-TMC, in-situ degradation, in-patient degradation, strength retention, resorbable craniofacial implants, fatigue..