Effects of bioresorbable magnesium-based materials on bone healing: a preclinical study in a large growing-animal model

3F5Q1 ePOSTER CLINICAL INNOVATIONS

Background: Over the last decade, the development of new and alternative materials has been focused in many research fields. In recent years promising results have been achieved using magnesium (Mg)-based alloys as biodegradable metallic implants. With a similar density and Young's modulus to bone, the alloys are homogeneously resorbable, biocompatible, osteoconductive and also used as functionally supportive implant.

Aim/Hypothesis: The aim of the study was to investigate the clinical applicability of Mg-based alloy without rare earth elements in a growing sheep model with osteotomized bone compared to a NO-osteotomy control group regarding degradation behaviour, growth regulation and fracture healing.

Materials and Methods: Eleven one-month-old female lambs were randomized into three groups (3, 6 and 12 weeks). Within the groups, right tibiae were osteotomized imitating a fracture and received screw fixation using two Mg-based screws into the epiphyseal area, whereas left tibiae underwent screw fixation without osteotomy (control). After 3, 6 and 12 weeks μCT and histology of the explanted tibiae were performed and 3D calculated to determine screw degradation, gas evolution, influence in-growth and fracture consolidation.

Results: The screw volume was significantly (P < 0.05) reduced for 3, 6 and 12 weeks post-surgery compared to the initial volume. During 12 weeks, this volume reduced from 198.4 mm3 (± 0.9 mm³) to 181.21 mm³ (± 6.11 mm³). In both side (proximal and distal) of implants, gas volume increased significantly between week 3 and week 12. No negative effects on longitudinal bone growth were detected. In case of osteotomized tibiae, fracture consolidation was observed in all cases after 12 weeks. No significant differences between the osteotomized side and the control side were found, neither in screw volume, nor in gas production.

Conclusions and Clinical Implications: Mg screw degradation related to hydrogen gas evolution was not associated with adverse effects on fracture consolidation or longitudinal bone growth in juvenile bones. The fracture healing process should not have any significant influence on the degradation behavior. Mg-based implant has showed interesting biomechanical, bioresorbable and biocompatible properties. Bioresorbable materials based on magnesium have therefore applications in the field of dentistry, oral and maxillofacial surgery.

Keywords: Implant, Bioresorbable, Magnesium, Screw