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

Thermomechanical andin vitrobiological characterization of injection-molded PLGA craniofacial plates

“…Due to its lower elastic modulus compared to metal implants, and gradual degradation, the choice of these materials protects against bone weakening due to stress shielding and avoids the need for subsequent surgery. 7,[10][11][12][13] Moreover, the application of bioresorbable implants is particularly advantageous for pediatric patients, since intracranial translocation of plates and screws as well as problems associated with metallic implants, such as tenderness, palpability, visibility, and thermal sensitivity, can be prevented. 1,10 PLA/PGA copolymers (poly(lactic-co-glycolic acid), PLGA) are under constant development and investigation as materials for craniofacial plate production.…”

“…17 The investigated plate geometry was based on commercially available devices. 10 The influence of the processing temperature on the material properties was investigated; in particular, two processing temperatures, 240°C (PLGA_lowT) and 280°C (PLGA_highT) were evaluated. PLGA_lowT was chosen as the minimum processability temperature while PLGA_highT was defined as the upper working limit temperature without possible polymer degradation.…”

Biomechanical Analysis of Biodegradable Cervical Plates Developed for Anterior Cervical Discectomy and Fusion

“…A biodegradable plate system has been introduced to overcome these problems. Biodegradable plate systems are typically absorbed within 6 months to 1 year postoperatively, and if dysphagia occurs, it does not persist after this period [13,2 5,26]. Dysphagia can be reduced because the mass effect of the plate disappears.…”

Resorbable Pins to Enhance Scaffold Retention in a Porcine Chondral Defect Model

“…This study utilized bioresorbable PLDLLA (poly(l-lactideco-d,l-lactide)) pins (Aesculap FR736, Center Valley, PA) with pin diameter of ~0.90 mm, head diameter of ~1.25 mm, and length of ~6 mm. Resorption of PLDLLA typically occurs on the order of months, 21,22 fitting the timeline of the long-term study. For implantation, a pilot hole was first created in the subchondral bone.…”