The standard sagittal starting point and entry angle for tibia intramedullary nails results in malreduction of proximal tibial fractures.

ABSTRACT

INTRODUCTION: The aim of this study was to determine the sagittal starting point and entry angle necessary for anatomic reduction in proximal tibial fractures and to compare reductions obtained using a standard versus modified sagittal entry angle. METHODS: Extra-articular proximal tibial fracture sawbone models were divided into three groups. The first group was used to determine the sagittal starting point and entry angle necessary for an anatomic reduction by inserting nails into the distal fragment and then reducing the proximal fragment over the nail. The second and third groups had nails inserted through the standard coronal and sagittal starting point using the standard sagittal entry angle (parallel to the anterior cortex) versus a more posteriorly directed modified sagittal entry angle (directed at the center of the tibia at the level of the tibia tubercle prominence). Fracture gapping and translation in the sagittal plane were measured for each group. RESULTS: Anatomic reduction was only possible with a sagittal starting point that was too posterior for actual use. The standard sagittal entry angle resulted in greater posterior fracture translation and less anterior fracture gapping then the modified sagittal entry angle, 10.6 ± 1.1 versus 1.6 ± 2.8 mm (p < 0.01) and 1.3 ± 0.5 versus 5.3 ± 2.5 mm (p = 0.01), respectively. CONCLUSION: Anatomic reduction was not achieved with the standard sagittal starting point and entry angle. Considering these finding, surgeons should have a low threshold to utilize adjunct reduction methods for these injuries.