Biomechanical comparisons of unidirectional and bidirectional Kirschner-wire insertion

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Veterinary surgery

Background:

• Kirschner-wires (K-wires) are commonly used for bone fracture fixation.
• Drilling methods can influence K-wire insertion forces and fixation stability.
• Potential for soft-tissue damage exists with unidirectional drilling techniques.

Purpose of the Study:

• To compare the biomechanical performance of K-wires inserted using unidirectional versus bidirectional drilling.
• To evaluate the effect of drilling direction on axial entry and pull-out loads.
• To assess the clinical utility of bidirectional drilling for K-wire placement.

Main Methods:

• Canine metacarpals were used as a bone model.
• K-wires were inserted using both unidirectional and bidirectional drilling methods.
• Trocar-tip and diamond-tip K-wires were tested.
• Peak axial loads on entry and peak pull-out loads were measured.

Main Results:

• Trocar-tip K-wires showed similar entry loads for both drilling methods.
• Bidirectional insertion of trocar-tip K-wires resulted in lower pull-out loads than unidirectional insertion, but remained clinically useful.
• Diamond-tip K-wires exhibited higher entry loads and lower pull-out loads with bidirectional drilling.

Conclusions:

• Bidirectional drilling offers comparable fixation to unidirectional drilling for trocar-tip K-wires.
• Bidirectional insertion may mitigate risks of soft-tissue damage associated with unidirectional drilling.
• The findings support the potential clinical application of bidirectional drilling in orthopedic fixation.