To investigate the risk predictors of early femoral head necrosis (FHN) after femoral neck system (FNS) treatment for femoral neck fractures of Pauwels type I to type III.

From January 2020 to July 2024 120 patients with femoral neck fractures in the Affiliated Hospital of Chengdu University were retrospectively selected. Inclusion criteria: unilateral traumatic femoral neck fracture, aged from 18 to 65 years, clear surgical indications, complete data; exclusion criteria: pathological fracture, immune disease, history of hormone use, malignant tumor. and treated with FNS after admission. According to the presence or absence of occurrence of early FHN, the enrolled patients were divided into femoral head necrosis group (FHN group, n=39) and non-femoral head necrosis group (non-FHN group, n=81). The general data, laboratory indicators and perioperative indicators in the two groups were collected. The differences in related factors of FHN between groups were compared by univariate analysis. The independent influencing factors of FHN were screened by multivariate logistic model, and the predictive efficiency of each factor on the risk of early FHN was analyzed by receiver operating characteristic curve.

There was a statistical difference in Pauwels type composition between the FHN group and the non-FHN group (χ²=2.629, P=0.009). The waiting time from fracture to surgery, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), C-reactive protein (CRP), interleukin (IL)-6 and IL-33 in the FHN group were longer or higher than those in the non-FHN group while the β-C-terminal telopeptide of type I collagen (β-CTX) and pro-collagen I N-terminal pro-peptide (P1NP) were lower, with statistical difference (all P<0.05). After logistic regression analysis, it was found that the waiting time from fracture to surgery, NLR, IL-6, β-CTX and P1NP were the influencing factors for early FHN. As for predicting early FHN alone and in combination with waiting time from fracture to surgery, NLR, IL-6, β-CTX and P1NP, the sensitivities were 0.513, 0.821, 0.718, 0.872, 0.667 and 0.974 respectively; the specificities were 0.765, 0.889, 0.889, 0.556, 0.864 and 0.951; the Yoden indices were 0.278, 0.709, 0.607, 0.427, 0.531 and 0.925; the areas under the curves were 0.683, 0.924, 0.829, 0.748, 0.801 and 0.993 respectively.

The risk factors for postoperative early FHN in patients with femoral neck fractures treated with FNS for different fracture types include the waiting time from fracture to surgery, NLR, IL-6, β-CTX and P1NP. The combination of various factors has extremely high efficiency on predicting the occurrence of FHN and has great clinical promotion value.