title: Evaluation of the Fatigue Performance and Degradability of Resorbable PLDLLA-TMC Osteofixations.
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.
authors.affiliation: Oral, Craniomaxillofacial and Plastic Facial Surgery, The Center of Surgery, Goethe University Medical Centre, Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Landes
authors.affiliation: Oral, Craniomaxillofacial and Plastic Facial Surgery, The Center of Surgery, Goethe University Medical Centre, Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ballon
authors.affiliation: Oral, Craniomaxillofacial and Plastic Facial Surgery, The Center of Surgery, Goethe University Medical Centre, Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
authors.forename: Shahram
authors.initials: S
authors.lastname: Ghanaati
authors.affiliation: Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ebel
authors.affiliation: Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Ulrich
authors.affiliation: Fraunhofer Institute for Mechanics of Materials IWM, Biological and Biocompatible Materials - group, Fraunhofer-IWM, Walter-Hülse-Str. 1, 06120 Halle.
authors.forename: Uwe
authors.initials: U
authors.lastname: Spohn
authors.affiliation: Fraunhofer Institute for Mechanics of Materials IWM, Biological and Biocompatible Materials - group, Fraunhofer-IWM, Walter-Hülse-Str. 1, 06120 Halle.
authors.forename: Ute
authors.initials: U
authors.lastname: Heunemann
authors.affiliation: Oral, Craniomaxillofacial and Plastic Facial Surgery, The Center of Surgery, Goethe University Medical Centre, Frankfurt, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Sader
authors.affiliation: Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg, Germany.
authors.forename: Raimund
authors.initials: R
authors.lastname: Jaeger
keywords: PLDLLA-TMC; PLLA; Polylactic acid; fatigue.; in-patient degradation; in-situ degradation; resorbable craniofacial implants; resorbable osteofixation; resorbable osteosyntheses; strength retention