Cyclic loading of periprosthetic fracture fixation constructs.
Max Talbot1, Radovan Zdero, Emil H Schemitsch
1Canadian Forces, 1 Canadian Field Hospital, Martin Orthopaedics Biomechanics Laboratory, Toronto, Ontario, Canada. max_talbot@hotmail.com
The Journal of Trauma
|May 13, 2008
Summary
Allograft strut-plate fixation for femur fractures after hip arthroplasty provides superior bending stiffness and load to failure compared to locking plates alone. Constructs maintained mechanical integrity after cyclic loading.
Area of Science:
- Orthopedic surgery
- Biomechanical engineering
- Materials science in medical devices
Background:
- Femur fractures are a frequent complication following hip arthroplasty.
- When the hip arthroplasty stem is stable, treating the femur fracture is prioritized.
- Various fixation techniques, including plates and allograft struts, are utilized.
Purpose of the Study:
- To compare the mechanical properties of different fixation methods for Vancouver type B1 periprosthetic femur fractures.
- To evaluate the efficacy of allograft struts in conjunction with plating systems.
- To assess construct stability under cyclic loading conditions.
Main Methods:
- Vancouver type B1 fractures were created in composite femurs with cemented hip stems.
- Fixation methods included nonlocking plate/allograft strut, locking plate/allograft strut, and locking plate alone, with struts secured by cables.
- Cyclic loading (100,000 cycles) was applied, followed by mechanical testing for stiffness (bending, torsion, axial) and load to failure.
Main Results:
- Constructs with allograft struts demonstrated significantly greater bending stiffness compared to the locking plate alone.
- The load to failure was significantly higher for constructs incorporating allograft struts.
- Cyclic loading had minimal impact on the mechanical properties of all tested constructs.
Conclusions:
- Allograft strut-plate constructs offer superior bending stiffness and load-bearing capacity over stand-alone locking plates for these fractures.
- The use of locking screws did not provide a significant mechanical advantage when combined with an allograft plate construct.
- All tested fixation methods maintained their mechanical integrity after substantial cyclic loading, indicating durable fixation.
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