Mechanical comparison of two small interlocking nails in torsion using a feline bone surrogate

Area of Science:

• Veterinary Orthopedics
• Biomechanical Engineering
• Surgical Implant Technology

Background:

• Fracture repair in felines often requires stable fixation.
• Interlocking nails and locking compression plates (LCP) are common osteosynthesis options.
• Torsional stability and the effects of implant removal are critical factors in construct success.

Purpose of the Study:

• To compare the torsional behavior of I-Loc and Targon interlocking nails against locking compression plates (LCP).
• To assess the impact of implant removal on the torsional strength of feline bone surrogates.

Main Methods:

• Experimental comparison of six implants (I-Loc, Targon, LCP) in feline bone surrogates.
• Cyclic torsional testing of fracture gap constructs (n=4/group).
• Torsion to failure testing of intact surrogates with implant-specific pilot holes to simulate removal (n=4/group).

Main Results:

• I-Loc 4 demonstrated the lowest torsional compliance and angular deformation.
• Targon 2.5 exhibited significant locking interface slippage and the highest angular deformation.
• Targon nails resulted in the lowest failure torque, while I-Loc and LCP showed no difference from intact bone.

Conclusions:

• I-Loc nails provide superior torsional stability over Targon nails and LCPs.
• Targon 2.5's locking interface slippage compromises construct stability.
• Large Targon bolt holes increase the risk of iatrogenic fracture after explantation.