Summary
Objectives: The biomechanical properties of standard plates and recently designed locking plates
were compared in torsion. We hypothesized that titanium (Ti) constructs would have
the greatest deformation, and String of Pearls (SOP) constructs the greatest strength
and stiffness.
Methods: Dynamic compression plates (DCP), stainless steel (SS) limited contact (LC)-DCP,
Ti LC-DCP, locking compression plate (LCP), 10 mm and 11 mm Advanced Locking Plate
System (ALPS) 10 and 11, SOP and Fixin plates were applied to a validated bone model
simulating a bridging osteosynthesis. Yield torque (strength), yield angle (deformation)
and stiffness were compared using one-way ANOVA with post hoc Tukey (p <0.05).
Results: The ALPS 11 constructs had significantly greater elastic deformation than all constructs
except for the ALPS 10. There were not any differences in strength observed except
for the ALPS 10 constructs, which was less than that for the SOP, LCP, DCP and ALPS
11 constructs. No differences in construct torsional stiffness were observed with
the SS LCDCP, DCP, LCP and SOP constructs however all had greater stiffness than all
remaining constructs. The ALPS 10 construct had lower stiffness than all constructs.
Clinical significance: Modulus of elasticity of Ti explains the higher deformation and lower stiffness of
these systems, with similar results for the Fixin due to its lower section modulus
compared to all other plates. The SOP and standard constructs had surprisingly similar
biomechanical properties in torsion. The rationale for selecting these implants for
fracture repair likely needs to be based upon their differing biomechanical properties
inherent to the diverse implant systems.
Presented at the 38th Annual Conference of the Veterinary Orthopedic Society, Snowmass, Colorado, USA March
6, 2011.
Keywords
Torsion - bone plates - locking plates -
in vitro
- plate failure
