TS05 *MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS: ADVANCED EARLY FRACTURE HEALING IN A SHEEP TRAUMA MODEL

Abstract

Introduction: Minimally invasive plate osteosynthesis (MIPO) has become a clinically accepted method with good results, when compared to the open surgical approach (ORIF). However, while MIPO offers some advantages over ORIF, it also has some significant drawbacks. No experimental study to date showed a difference between the healing outcomes in fractures treated with the two surgical approaches. Therefore, we developed a novel, standardised severe trauma model in sheep, and used it to examine the effect of the two surgical approaches on soft tissue and fracture healing.Methods: 24 sheep were subjected to a soft tissue damage and a distal femur fracture. The fracture was initially stabilised with an external fixator. After 5 days of soft tissue recovery, internal plate fixation was applied via MIPO or ORIF. The sheep were sacrificed in 2 groups after 4 and 8 weeks, and CT scans and mechanical testing performed.Results: After 4 weeks, torsional stiffness was significantly higher in the MIPO group (30.1 ± 10.6% (SD) of fractured to intact contralateral bone; p = 0.018) compared to the ORIF group (9.8 ± 12.4%). The torsional strength also showed increased values for MIPO technique (p = 0.11). The callus volumes were higher in the ORIF group (19 141 ± 8511 mm3) than those of MIPO (15 596 ± 6194 mm3). After 8 weeks, the trends observed at 4 weeks continued without statistical significance.Conclusion: The surgical approach does influence the healing process of fractures. The MIPO technique led to a smaller, denser fracture callus with superior mechanical properties. This clinically related experimental trauma and treatment model indicates that MIPO leads to an advanced early fracture healing.