Background The semi-extended tibial intramedullary nailing method would enable easier and improved reductions for tibial fractures as well as facilitate fluoroscopic imaging; however, its in-articular nature remains controversial. The aim of this study was to compare the clinical and functional outcomes of the semi-extended infrapatellar (SEIP) approach and hyper-flexed infrapatellar (HFIP) approach for intramedullary nailing to treat tibial shaft fractures.MethodsThis study involved the retrospective analysis of the medical records of patients with tibial shaft fractures that were fixed through either the SEIP approach or the HFIP approach of intramedullary nailing and who were admitted to a level 1 trauma center. The minimum patient follow-up period was 12 months and the clinical and functional outcomes were estimated at the 12-month visit. ResultsOf the 80 patients whose medical records were analyzed, 40 (50%) underwent SEIP nailing and the remaining 40 (50%) underwent the traditional HFIP nailing. Compared with the HFIP group, patients in the SEIP group had a higher Lysholm knee score (median, 92 [interquartile range, 88-95] vs median, 88 [interquartile range, 81-92]; p = .01), a shorter intraoperative fluoroscopy time (median, 93 [interquartile range, 78-105] s, vs median, 136 [interquartile range, 110-157] s; p < .001), and operation time (mean, 88.1 [SD, 17.8] min vs mean, 98.7 [SD, 19.3] min; p = .01). The VAS score was significantly lower in the SEIP group (median, 0; interquartile range, 0-0) than in the HFIP group (median, 0; interquartile range, 0-2) (p = .03). There were two cases (5%) in the SEIP group and 10 cases (25%) in the HFIP group of moderate AKP (p = .03). Meanwhile, there was no significant difference in malalignment, nonunion, delayed union, infection, and other complications, as well as SF-36 physical and mental scores.ConclusionWe found that the SEIP approach to tibia intramedullary nailing was superior to the HFIP approach based on the intraoperative and postoperative outcomes. Thus, this novel technique provides an infrapatellar option for semi-extended tibial nailing.