Radiographic Evaluation of the Tibial Intramedullary Nail Entry Point

INTRODUCTION: Tibia fractures are common injuries that can often be effectively treated with intramedullary nail (IMN) fixation. The ideal starting point for IMN reaming and nail placement is well described and regarded as a crucial aspect in the technique. The purpose of this study is to determine the accuracy and precision with which the starting point is established and if this is maintained after nail insertion during fracture fixation. METHODS: Fifty consecutive tibia fractures treated by IMN fixation sized 9 to 13 mm through an infrapatellar or medial parapatellar approach and 50 treated with a suprapatellar approach were evaluated. The starting point for reaming and IMN placement was measured using intraoperative fluoroscopy. Postoperative radiographs were used to determine the center of the IMN after placement. The distance between the measured points and the ideal starting point was measured. RESULTS: Deviation from the ideal entry point on intraoperative fluoroscopy averaged 4.6 ± 4.0 mm medially, 2.9 ± 3.7 mm anteriorly, and 2.7 ± 3.3 mm distally. In 30% of cases, the final IMN position varied from the entry point by greater than one SD in the coronal or sagittal plane. No difference between approaches was appreciated. DISCUSSION: Although the ideal starting point for tibial IMN fixation is known, this is frequently not the starting point accepted in practice. Final position of the IMN is independent of IMN size or approach and is not markedly different than the obtained starting point. LEVEL OF EVIDENCE: Therapeutic level III.