RESUMO
OBJECTIVE: The objective of this study was to analyze the ratio of fracture site diameter to tibial isthmus diameter (TFI ratio) as a predictor of postoperative complications, including malunion and delayed union, after tibial intramedullary nailing for middle and lower tibial fractures. METHODS: Data were collected from all adult patients older than 20 years of age who underwent tibial intramedullary nailing for middle and lower tibial fractures between January 2015 and January 2023 and were followed up for at least 1 year. Diabetes history, smoking history, fracture type, injury mechanism, surgical method, surgical approach, diameter of the medullary cavity at the fracture site, and diameter of the tibial isthmus were recorded. Logistic regression analysis was used to determine the variables affecting the occurrence of complications. The TFI ratio was used to calculate the sensitivity and specificity of the parameters, and ROC curves were generated to establish TFI ratio thresholds for predicting complications. RESULTS: A total of 123 patients with middle and lower tibial fractures were treated with intramedullary nails. The mean age of the patients was 43.72 years (range, 21-81 years); 89 were males, and 34 were females. Univariate logistic regression analysis showed that fracture type, open reduction surgery, superior patellar approach, and TFI ratio were significantly correlated with postoperative complications after intramedullary nailing of a tibial fracture. Multivariate logistic regression analysis showed that the TFI ratio was an independent risk factor for complications (P = 0.001*). By using the TFI ratio as a predictor of complications, an ROC curve was generated to establish a threshold. The ROC curve showed that a TFI ratio ≥ 1.31 had a sensitivity of 0.89, a specificity of 0.71, and an area under the ROC curve of 0.82 for predicting complications. CONCLUSIONS: The results of this study suggest that a wider intramedullary diameter and a shorter fixed length at the fracture site are associated with a higher incidence of complications after tibial intramedullary nailing. The TFI ratio may be used as a reliable parameter for predicting complications after such surgery. In patients with a high TFI ratio (≥ 1.31), additional reduction and fixation techniques may be needed to obtain and maintain fracture reduction.
