Perioperative Radiographic Predictors of Non-Union in Infra-Isthmal Femoral Shaft Fractures after Antegrade Intramedullary Nailing: A Case–Control Study

Abstract

Antegrade intramedullary (IM) nailing is the gold standard treatment for femoral shaft fractures; however, the non-union rate of infra-isthmal femoral shaft fractures is still high after antegrade IM nailing. This retrospective case–control study aimed to determine the association between perioperative radiographic factors and the non-union of infra-isthmal femoral shaft fractures after antegrade IM nailing. Univariate and multivariate analyses were used to evaluate the radiographic risk factors of non-union. Ninety-three patients were included, with thirty-one non-unions and sixty-two matched controls between 2007 and 2017. All were regularly followed up for 2 years. Receiver operating characteristic analysis revealed that a ratio of the unfixed distal segment >32.5% was strongly predictive of postoperative non-union. The risk factors for non-union were AO/OTA type B and C (odds ratio [OR]: 2.20), a smaller ratio of the distal fragment (OR: 4.05), a greater ratio of the unfixed distal segment (OR: 7.16), a higher ratio of IM canal diameter to nail size at the level of fracture (OR: 6.23), and fewer distal locking screws (OR: 2.31). The radiographic risk factors for non-union after antegrade IM nailing for infraisthmal femoral shaft fractures were unstable fractures, shorter distal fragments, longer unfixed distal fragments, wider IM canal, and fewer distal locking screws. Surgeons must strive to avoid non-union with longer and larger nails and apply more distal locking screws, especially for unstable, wider IM canal, and shorter distal fragment fractures.