Abstract
Aims: Several designs are available to the surgeon for internal fixation with plates. This study compares the mechanical behaviour of three different designs for screw-plate locking: threaded screw head (Type1), conical joint with titanium insert (Type2) and spherical 3-point wedge-locking (Type3).
Methods: 3D-CAD and FEM models were used to simulate the behaviour of each device component. Two typical loading conditions were considered in order to characterize joint mechanics: screw tension and bending.
Results: The screws performances were compared in terms of stress concentration factors (SCF) with reference to the screw nominal diameter. In particular, Type3 device exhibits a strong influence of screw tightening on SCF. Results can be summarized as follows:
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Tension: SCF_T-Type1=4.8; SCF_T-Type2=3.2; SCF_ T-Type3=11.7;
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Bending: SCF_B-Type1=2.45; SCF_B-Type2=1.44; SCF_B-Type3=2.52.
Conclusions: With respect to classic Type1 screw, Type2 device provides a better load distribution while Type3 system offers pivoting capabilities at the expenses of higher stresses acting on the joint.
The abstracts were prepared by incoming Professor Elena Brach del Prever. Correspondence should be addressed to IORS – President office, Dipartimento di Traumatologia, Ortopedia e Mediciana del Lavoro, Centro Traumatologico Ortopedico - Via Zuretti, 29 I-10135 Torino, Italy.
