In Vitro Wire Tension in Circular External Fixation Frames.

Area of Science:

• Orthopedic biomechanics
• Biomaterials engineering

Background:

• Circular frames are vital for fracture and osteotomy management, but their clinical performance varies due to individualization.
• Wire tension in fine wire constructs is critical for stability but can degrade, with limited understanding of influencing factors.

Purpose of the Study:

• To monitor wire tension in an in vitro circular frame construct.
• To investigate clinical assembly and use factors affecting wire tension loss in external fixation.

Main Methods:

• Utilized strain gauge instrumented wires in a symmetrical circular frame.
• Monitored wire tension under varying assembly conditions and dynamic loading.

Main Results:

• Variability in wire tension was linked to tensioner application and wire slippage, primarily due to bolt torque.
• These factors could cause up to a 50% variation in achieved wire tension.
• Despite initial slippage, wire tension remained stable under dynamic loading after three cycles.

Conclusions:

• Consistent frame performance requires a calibrated tensioner set to high initial tension (110 kg).
• Controlled wire clamp bolt torque (14 Nm) is essential for minimizing tension loss and ensuring predictable outcomes.