Pullout strength of 2.0 mm cancellous and cortical screws in synthetic bone.

Objective: To determine whether 2.0 mm cancellous screws are superior to 2.0 mm cortical screws when inserted into cancellous and bicortical bone.

Study Design: Biomechanical study.

Methods: The 2.0 mm cancellous screws and 2.0 mm cortical screws were inserted according to the recommended guidelines in synthetic cancellous and bicortical blocks. Fifteen screw-block constructs per group were tested to failure in axial pullout. Axial pullout strength and yield strength were calculated. Data were analyzed using a one-way ANOVA.

Results: The 2.0 mm cortical screws achieved lower axial pullout strength than 2.0 mm cancellous screws in cancellous blocks. The 2.0 mm cortical screws achieved greater pullout strength than 2.0 mm cancellous screws in bicortical blocks.

Conclusion: The 2.0 mm cancellous screws may offer a biomechanical advantage in bone with thin cortices (<1 mm thick), whereas 2.0 mm cortical screws may be preferred in cortical bone with cortices measuring at least 1 mm in thickness.