Objective Engineering monitoring methods were adopted to compare the effects of PFNA and InterTAN on elderly patients with intertrochanteric fractures, including bone metabolism dynamics, limb function recovery and endograft stability. Methods A total of 104 elderly cases of intertrochanteric fractures admitted to the Department of Orthopedics and Traumatology, Xuchang Hospital of Traditional Chinese Medicine from April 2022 to February 2024 were selected and all underwent surgical treatment and were included in the research cohort. The subjects were grouped based on different internal fixation regimens (the control group and the observation group). The control group (n=52) was treated with InterTAN internal fixation, while the patients in the observation group (n=52) were treated with PFNA internal fixation. The surgical indicators, bone metabolism parameters, limb function scores and postoperative complications of the two groups were compared and analyzed. Results The intraoperative operation time in the observation group was significantly shorter than that in the control group, and the amount of blood loss was significantly reduced (all P<0.05). After the operation, the OC level of patients in the observation group was higher than that of patients in the control group, while the β-CTX level and iPTH level were lower than those in the control group (P<0.05). After the operation, the Harris score and FMA-LE score of the patients in the observation group were higher than those in the control group (P <0.05). There was no statistically significant difference in the cumulative incidence of postoperative complications between the two groups (P>0.05). At 1 month and 3 months after the operation, the walking speed and the ROM of flexion and extension of the affected hip joint in the observation group were significantly better than those in the control group (P <0.05). By 6 months after the operation, there was no statistically significant difference in walking speed and hip joint ROM between the two groups (P>0.05). Conclusion PFNA internal fixation in elderly with intertrochanteric fractures can improve the therapeutic effect, enhance the postoperative bone metabolism level of patients, and improve the prognosis limb function. Moreover, PFNA surgery is significantly superior to InterTAN surgery in early functional recovery (a 15.2% improvement in gait symmetry). Engineering assessment tools can provide an objective basis for the selection of clinical surgical procedures.