Biocompatibility and healing patterns in experimentally induced canine tibial fractures using Pedicle screw-Rod external fixation.

Abstract

Background: Biological osteosynthesis preserves blood supply and promotes rapid healing by aligning fracture fragments without direct surgical exposure. Pedicle screws are primarily designed for internal fixation in spinal procedures. A key objective of many orthopedic studies is to assess the biocompatibility of implants with bone and adjacent soft tissue. This study aims to evaluate the biocompatibility and effects of the Pedicle screw-Rod configuration as a novel external fixation method in canine tibial osteotomy.

Methods: With ethics approval, eight healthy, intact male dogs, aged 10-12 months and weighing between 20 and 22 kg, underwent a minimally invasive medial tibial approach for surgical fixation of tibial osteotomy using a Pedicle screw-Rod configuration. Postoperative evaluations included ultrasound assessments at the osteotomy site and histological evaluations at the bone-screw interface.

Results: B-mode ultrasound evaluation indicated healing progress at all osteotomy sites. The color Doppler examination revealed an initial increase in signals in the surrounding soft tissue during the first 4 weeks post-operation, followed by a decrease in signals within the adjacent soft tissue between the 5th and 8th weeks. During this latter period, the signals were primarily concentrated on the bone surface and the callus. The bone-screw interface at various screw sites exhibited similar histological changes, indicating effective integration of the newly formed woven bone into the screw threads.

Conclusions: Fixation of non-articular tibial osteotomy with Pedicle screw-Rod configuration resulted in secondary bone healing, characterized by abundant callus formation and neovascularization. This implant demonstrated favorable biocompatibility with bone and surrounding soft tissue, without significant complications.