Detailing the influence of PEO-coated biodegradable Mg-based implants on the lacuno-canalicular network in sheep bone: A pilot study

An increasing prevalence of bone-related injuries and aging geriatric populations continue to drive the orthopaedic implant market. A hierarchical analysis of bone remodelling after material implantation is necessary to better understand the relationship between implant and bone. Osteocytes, which are housed and communicate through the lacuno-canalicular network (LCN), are integral to bone health and remodelling processes. Therefore, it is essential to examine the framework of the LCN in response to implant materials or surface treatments. Biodegradable materials offer an alternative solution to permanent implants, which may require revision or removal surgeries. Magnesium alloys have resurfaced as promising materials due to their bone-like properties and safe degradation in vivo. To further tailor their degradation capabilities, surface treatments such as plasma electrolytic oxidation (PEO) have demonstrated to slow degradation. For the first time, the influence of a biodegradable material on the LCN is investigated by means of nondestructive 3D imaging. In this pilot study, we hypothesize noticeable variations in the LCN caused by altered chemical stimuli introduced by the PEO-coating. Utilising synchrotron-based transmission X-ray microscopy, we have characterised morphological LCN differences around uncoated and PEO-coated WE43 screws implanted into sheep bone. Bone specimens were explanted after 4, 8, and 12 weeks and regions near the implant surface were prepared for imaging. Findings from this investigation indicate that the slower degradation of PEO-coated WE43 induces healthier lacunar shapes within the LCN. However, the stimuli perceived by the uncoated material with higher degradation rates induces a greater connected LCN better prepared for bone disturbance.

Automated summary

The increasing prevalence of bone-related injuries and aging geriatric populations are driving the growth of the orthopaedic implant market. A hierarchical analysis of bone remodelling after material implantation is necessary to understand the relationship between implant and bone. Osteocytes play a vital role in bone health and remodelling processes, making it essential to examine the lacuno-canalicular network (LCN) in response to implant materials. Biodegradable materials, such as magnesium alloys, offer a potential solution to permanent implants, and surface treatments like plasma electrolytic oxidation (PEO) can slow degradation. This study investigates the impact of PEO-coated WE43 on the LCN using nondestructive 3D imaging, and the findings suggest that slower degradation induced by PEO-coating results in healthier lacunar shapes within the LCN.