BIOMECHANICAL STUDY OF PULLOUT RESISTANCE OF CORTICAL SCREWS IN SWINE LUMBAR VERTEBRAE.

INTRODUCTION

This study aimed to evaluate the mechanical resistance to pullout of the lumbar cortical bone trajectory (CBT) screw with and without transfixation of the second cortical in a biomechanical assay in swine vertebrae.

METHODS

A pullout test was performed in 16 swine vertebrae (L5 and L6) fixed with 32 CBT screws using the same protocol. Of these, 16 were inserted in a monocortical manner according to the original technique and 16 through a modified technique which included the transfixation of the second cortical bone.

RESULTS

The average maximum load value for pulling out the inserted screws with the modified technique including the transfixation of the second cortical bone was 140.50 Kgf (± 56.56), while in the original technique it was 95.69 Kgf (± 42.19) (p = 0.004).

CONCLUSION

The biomechanical tests applied to the studied sample showed that the pullout resistance of the CBT screws inserted with the bicortical technique was, on average, 46% higher than the screws inserted according to the original monocortical technique. Level of Evidence II; Experimental study.