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Structural properties of interlocking nails, canine femora, and femur-interlocking nail constructs
R T Dueland1, L Berglund, R Vanderby
1Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, USA.
Veterinary Surgery : VS
|September 1, 1996
Summary
This study evaluated interlocking nails (IN) for stabilizing canine femur fractures. Larger diameter IN (8 mm) demonstrated superior stiffness and strength, suggesting they provide adequate stabilization for canine femoral fractures.
Area of Science:
- Orthopedic biomechanics
- Veterinary surgery
- Biomaterials science
Background:
- Interlocking nails (IN) are used to stabilize bone fractures.
- Understanding the biomechanical properties of IN in canine femora is crucial for effective fracture treatment.
- Previous studies have not fully characterized the performance of different IN sizes and screw configurations in canine models.
Purpose of the Study:
- To determine the structural properties of interlocking nails (IN), canine femora, and IN/femur constructs.
- To compare the biomechanical performance of 6 mm and 8 mm IN in intact and fractured canine femora.
- To evaluate the adequacy of 8 mm IN with varying screw configurations for stabilizing canine diaphyseal femoral fractures.
Main Methods:
- Standard material testing techniques were employed, including bending stiffness, torsional stiffness, and maximum torque to failure.
- Specimens included intact canine femora, interlocking nails (6 and 8 mm diameters), intact constructs (femur with IN), and fracture model constructs (femur with transverse osteotomy and IN).
- Various screw configurations (3.5 mm and 4.5 mm diameter) were used in conjunction with the IN in both intact and fracture models.
Main Results:
- Eight-millimeter IN exhibited significantly greater torsional (220%) and bending (270%) stiffness compared to 6 mm IN.
- Eight-millimeter IN approached the stiffness of intact canine femora (93% bending, 79% torsional).
- Eight-millimeter interlocking nail/four screw constructs showed comparable torsional stiffness and maximum torque to intact femora, with 147% of intact bending stiffness, indicating effective stabilization.
Conclusions:
- Larger diameter (8 mm) interlocking nails provide superior biomechanical stability in canine femora compared to smaller diameter nails.
- The 8 mm IN, particularly with a four-screw configuration, offers mechanical properties comparable to intact femora.
- The 8 mm IN/four screw construct is recommended for providing adequate stabilization for canine diaphyseal femoral fractures.