The effect of devascularisation upon early bone healing in dynamic external fixation

Area of Science:

• Orthopedics
• Bone healing research
• Surgical innovation

Background:

• Osteotomies require robust blood supply for effective healing.
• External fixation systems provide stability but can impact local vascularity.
• Understanding vascularity's role in fracture healing is critical for clinical outcomes.

Purpose of the Study:

• To investigate the impact of periosteal devascularisation on early osteotomy healing in sheep tibiae.
• To assess the relationship between cortical blood flow and fracture healing under external fixation.
• To determine if early restoration of blood flow is essential for the osteogenic effects of dynamic fixation.

Main Methods:

• Sheep tibiae osteotomies were stabilized using an external fixation system (240 N/mm axial stiffness).
• Periosteal devascularisation was performed in experimental groups.
• Cortical and medullary blood flow were measured using the microsphere technique at 14 days.
• In vivo monitoring and post-mortem mechanical testing assessed healing progression.

Main Results:

• Devascularised osteotomies showed significantly reduced cortical blood flow (1.7 ml/min/100g) compared to well-vascularised controls (19.3 ml/min/100g) at 14 days.
• A significant increase in medullary blood flow was observed in devascularised sites.
• Delayed healing in devascularised osteotomies was confirmed by in vivo and mechanical testing.

Conclusions:

• Periosteal devascularisation impairs early osteotomy healing by compromising cortical blood flow.
• The osteogenic stimulus provided by dynamic external fixation appears dependent on the early re-establishment of cortical perfusion.
• Maintaining or restoring vascularity is essential for optimal fracture healing in stabilized osteotomies.