[Relationship and risk factors of osteonecrosis of femoral head after internal fixation of femoral neck fracture with serum bone metabolism and vasoactive factors].

Objective: To study the relationship between osteonecrosis of femoral head after internal fixation of femoral neck fracture and serum bone metabolism, vascular active factors, and analyze the risk factors.

Methods: Total 150 patients with femoral neck fracture who underwent reduction and internal fixation from April 2016 to April 2019 were selected, including 83 males and 67 females. According to whether there was necrosis of femoral head after operation, they were divided into necrosis group(32 cases) and non necrosis group (118 cases). Before operation and 1, 3, 5 days after operation, the serum levels of beta-C terminal cross-linked telopeptides of typeⅠ collagen(β-CTX), N-telopeptide of typeⅠ procollagen(PINP), nitric oxide (NO), Endothelin-1 (ET-1) were measured. The clinical characteristics of the two groups were compared. The risk factors of postoperative femoral head necrosis were analyzed by logistic regression model. The value of serum indexes in predicting postoperative femoral head necrosis was analyzed by ROC curve.

Results: There was no significant difference in the levels of serum PINP and β-CTX between necrotic group and non necrotic group before operation and 1, 3 and 5 days after operation(>0.05). There was no significant difference in the levels of serum NO and ET-1 before operation and 5 days after operation(>0.05). There were significant differences in the levels of serum NO and ET-1(<0.05), fracture type, preoperative traction ratio and reduction quality (<0.05). Logistic regression analysis showed that the decrease of serum NO content and the increase of ET-1 content at 1 day after operation, Ⅲ-Ⅳ fracture and Ⅲ-Ⅳ reduction were the risk factors of femoral head necrosis;ROC curve analysis showed that serum NO and ET-1 content at 1 day after operation had predictive value for femoral head necrosis, and the best cut-off points were 26.55 μmol / L and 7.785 μg / L, respectively.

Conclusion: The content of serum NO and ET-1 on the first day after operation can predict the necrosis of femoral head.