[Experimental studies of segmental bone defects treated by skeletal external fixation]

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Vascular biology

Context:

• Tibial shaft defects and limb shortening pose significant clinical challenges.
• Limb lengthening procedures require stable fixation and adequate vascular supply for successful bone regeneration.
• Current treatments often face limitations in achieving complete bone defect restoration.

Purpose:

• To investigate the vascularization and healing processes in goat tibias undergoing lengthening with skeletal external fixation (SEF) after segmental resection.
• To evaluate the regional blood flow (RBF) dynamics during bone lengthening and defect repair.
• To establish the efficacy of SEF in promoting primary bone healing and vascular network formation in critical-sized bone defects.

Summary:

• Segmental tibial defects in goats were created and stabilized with SEF, followed by lengthening at 1.0 mm/d.
• Angiography, microvascular casting, and RBF measurements revealed extensive vascular network development in the lengthened bone, with vessels adapting to the lengthening rate and forming Haversian systems.
• The RBF in the lengthened zone peaked post-lengthening and remained significantly elevated, indicating robust vascularization. Primary bone healing was observed with stable fixation.

Impact:

• Demonstrates that SEF can support significant tibial lengthening and defect healing with substantial vascular ingrowth.
• Provides evidence for the adaptive capacity of blood vessels during distraction osteogenesis in a defect model.
• Offers a theoretical foundation for using SEF in treating complex tibial defects, nonunions, and associated limb shortening in clinical practice.