Ultrastructural Analysis of Infected Absorbable Bone Fixation Material Using Scanning Electron Microscopy After Zygomatic Bone Fracture Surgery

Absorbable bone fixation materials are commonly used in facial bone fracture surgery. However, reports on the microstructure of infected implants are rare. This study presents a case involving a 74-year-old male patient who developed an α-<i>Streptococcus</i> infection 2.5 months after zygomatic bone fracture surgery and the ultrastructure of an infected absorbable plate observed under a scanning electron microscope (SEM). The patient sustained a right zygomatic bone fracture due to a fall and underwent open reduction and internal fixation with SonicWeld on the seventh day after the injury. The postoperative course was uneventful, but 2.5 months after the surgery, the patient presented with redness, swelling, and pain in the right lower eyelid, along with purulent discharge, leading to the removal of the bone fixation material. The SEM observation of the extracted implant revealed a biphasic pattern, with areas showing signs of infection and areas without such effects. The infected regions showed wide cracks, bacterial clusters, and biofilm formation, whereas noninfected areas exhibited narrow cracks and distinct geometric striations. These findings suggest a link between crack formation and bacterial proliferation, emphasizing the importance of proper handling and implantation techniques. Although the infection was controlled and bone healing achieved after the removal of infected implants, the patient experienced lower eyelid retraction due to adhesion between the skin and underlying bone, leading to persistent cosmetic issues. This case report presents a rare visualization of the ultrastructural characteristics of infected absorbable implants, offering insights into the potential role of SEM in understanding these changes and processes.