Objective To analyze the relationship between serum levels of bone morphogenetic protein-2(BMP-2)and N-terminal middle molecular fragment of osteocalcin(N-MID)and postoperative hip joint dys-function in elderly patients with intertrochanteric fractures of the femur.Methods A total of 96 elderly pa-tients with intertrochanteric fractures of the femur who were treated in the hospital from February 2022 to June 2023 were selected.Based on the Harris score of postoperative hip joint function,they were grouped into a postoperative good group(n=67)and a postoperative poor group(n=29).Clinical data of all patients were collected,and serum levels of BMP-2 and N-MID were detected and compared.Spearman method was applied to analyze the relationship between serum BMP-2,N-MID levels and postoperative hip joint dysfunction in pa-tients.The influencing factors of postoperative hip joint dysfunction in patients were analyzed using Multivari-ate Logistic regression.The predictive value of serum BMP-2 and N-MID levels for postoperative hip joint dys-function in patients was analyzed using receiver operating characteristic(ROC)curve.Results There were obvious differences in Evans-Jensen classification of fractures,presence of postoperative complications,postop-erative internal fixation methods,and osteoporosis grading between the postoperative good group and the post-operative poor group(P＜0.05).The serum levels of BMP-2 and N-MID in the postoperative poor group were greatly lower than those in the postoperative good group,and the differences were statistically significant(P＜0.05).The serum levels of BMP-2 and N-MID in elderly patients with intertrochanteric fractures of the femur were negatively correlated with postoperative hip joint function(r=-0.564,-0.638,P＜0.05).Ev-ans-Jensen classification Ⅲ-Ⅴ,postoperative complications and osteoporosis grade 4-6 were all risk factors for postoperative hip joint dysfunction in elderly patients with intertrochanteric fractures of the femur(P＜0.05),while elevated serum BMP-2 and N-MID levels were protective factors(P＜0.05).The area under the curve(AUC)of single and combined detection of serum BMP-2,N-MID for postoperative hip joint dysfunc-tion in patients was 0.932,0.883,and 0.977,respectively,and the value of the combined detection was higher(Z combination-BMP-2=2.220,P=0.026;Z combination-N-NMID=3.162,P=0.002).Conclusion The serum levels of BMP-2 and N-MID in elderly patients with hip joint dysfunction after surgery for intertrochanteric fractures of the fe-mur are greatly reduced,and are negatively correlated with postoperative hip joint function.The combination of the two could better predict postoperative hip joint dysfunction in patients.