A multicentre retrospective cohort study was conducted within the Department of Orthopaedics at the First Affiliated Hospital of Fujian Medical University. This study reviewed 1,296 patients who underwent internal fixation treatment with ITF at the institution between 2020 and 2024. This study employed three distinct nutritional assessment tools for preoperative nutritional evaluation: CONUT, PNI, and NPS. By comparing the prevalence of malnutrition across these three scales and their relationship with FIF-ITF, an optimal predictive model combining INST with clinical factors was established.

A multicentre retrospective cohort study was conducted within the Department of Orthopaedics at the First Affiliated Hospital of Fujian Medical University. This study reviewed 1,296 patients who underwent internal fixation treatment with ITF at the institution between 2020 and 2024. Detailed documentation of patient information, including age, gender, affected side, bone mineral density (BMD), age-adjusted Charlson Comorbidity Index (aCCI), fracture type, internal fixation method, haematological parameters, implant-related complications (INSTs), and reasons for failure. This study employed three distinct nutritional assessment tools for preoperative nutritional evaluation: CONUT, PNI, and NPS. By comparing the prevalence of malnutrition across these three scales and their relationship with FIF-ITF, an optimal predictive model combining INST with clinical factors was established.

Inclusion Criteria:

• 1. Diagnosis of ITF on the basis of medical history, symptoms, imaging data, etc.; 2. Treatment by internal fixation surgery; 3. Normal cognitive function; and 4. Informed consent obtained from the patient or family.

Exclusion Criteria:

• 1. Significant missing data: In accordance with the Transparent Reporting of a Multivariate Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) statement, only cases with complete key variables (missing rate <5%) were included; 2. Severe preoperative systemic comorbidities (e.g., decompensated liver/renal failure, active pneumonia, malignancy, and cachexia) and/or a history of mental illness; and 3. Missing postoperative follow-up.

According to inclusion criteria, 1,296 patients undergoing internal fixation for intertrochanteric fractures at the aforementioned medical institutions between 2020 and 2024 were selected. All patients completed at least one year of follow-up. Follow-up comprised comprehensive orthopaedic examinations and serological tests, supplemented by repeat imaging where necessary to assess local fracture/internal fixation status.