Poster B10 - Development of Sensate Polymer-Ceramic Composites Scaffolds for Regeneration of Large Critical Size Bone Defects

Thursday, October 24, 2024

2:45 PM - 3:45 PM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Sabina Romero

Biomaterial Laboratory Undergraduate Researcher
University of Arizona
Nogales, Arizona, United States

Co-Author(s)

Gerardo Figueroa (he/him/his)

PhD Student
University of Arizona
San Luis, Arizona, United States
DG

David Gonzales

Laboratory Manager
University of Arizona, United States

Primary Investigator(s)

DM

David Margolis, MD, PhD

Assistant Professor, Orthopaedic Surgery
University of Arizona, United States

Co-Author(s)

JS

John Szivek

Professor
University of Arizona, United States

Introduction: Current treatments for long bone segment defects are costly, risky, and result in prolonged recovery. Our lab has previously noted that polybutylene terephthalate (PBT) scaffolds can regenerate critical size defects in sheep in 6 months. Although effective, PBT is bioinert. The combination of biodegradable and biocompatible polymers such as polylactic acid (PLA) and osteoconductive ceramics such as B-tricalcium phosphate (TCP) presents a promising alternative. However, the use of high-ceramic materials to produce bone regenerating scaffolds through freeform fabrication is limited due to the materials tendency to clog print heads, which restricts scaffold size. Our lab recently developed a high ceramic content composite material that can be used to produce bone regeneration scaffolds with freeform fabrication. In this study, we investigate the development of a large femoral scaffold using a 50/50 mixture of Polylactic Acid (PLA) and TCP for the treatment of large critical sized defects.

Materials and

Methods: Two different materials, PBT and a PLA/TCP mixture, were used for scaffold fabrication. PLA and TCP were combined at a 50/50 weight ratio and processed using an EX2 filament extruder. The 3D-printed scaffolds featured a trabecular pattern to mimic a bone porous structure (Figure 1). PBT scaffolds were produced using a Stratasys FDM 1650 printer. Composite scaffolds were produced utilizing a Piocreat G5 Pro printer with a 1mm nozzle, a print rate of 1800 mm/s, a printing temperature of 190°C, and a bed temperature of 65°C. Scaffolds were produced with a diameter of 25 mm, and of height of 42 mm. Strain gauges were glued onto the scaffold using a cyanoacrylate based adhesive. Scaffolds were tested in compression using a Material Testing System (MTS) while load and strain were recorded. This data was used to calculate stiffness of the scaffolds.

Results, Conclusions, and Discussions: The average weight of the PBT scaffold was 7.09 ± 0.04g, while the PLA/TCP scaffold weighed 15.16 ± 2.01g. Mechanical testing demonstrated that PLA/TCP scaffolds exhibited significantly higher stiffness (269.23 ± 43.12kg/mm) compared to PBT scaffolds (117.20 ± 25.15kg/mm) (Figure 2). The PLA/TCP scaffold failed at a load of 175 kg and a strain of 3500 με (Figure 3).

This study demonstrated that composite PLA/TCP scaffolds showed higher stiffness compared to PBT scaffolds. The failure load of the composite PLA/TCP scaffolds was sufficient to support the body weight of sheep. The high failure strain suggests that the scaffold can endure considerable deformation before failure. This is beneficial for mimicking the mechanical properties of natural bone.

Previous studies in our lab suggest that a biomimetic internal structure based on trabecular bone improves bone growth compared to the use of simple geometric pores. Previous use of these scaffolds in a rat model suggests that a 50/50 composite PLA/TCP scaffold supports increased bone regeneration compared to PBT scaffolds. Future studies will use a clinically relevant sheep model to determine whether composite scaffolds improve bone regeneration in large defects.

Acknowledgements (Optional):