An innovative scoring system for predicting an excellent Harris hip score after proximal femoral nail anti-rotation in elderly patients with intertrochanteric fracture

Typically, intramedullary and extramedullary devices are used to treat elderly with intertrochanteric fractures. The majority of previous research has focused on the association between surgical factors and mechanical failure after internal fixation. There is, however, limited evidence to demonstrate the association between functional outcomes after proximal femoral nail anti-rotation (PFNA) fixation and the non-surgical factors such as patient’s comorbidities. The aim of this study is to determine the predictive factors associated with excellent outcome, as well as to develop an integrated scoring system to predict the outcome after PFNA fixation in elderly patients with an intertrochanteric fracture. A retrospective study was conducted between January 2012 and December 2018. Elderly patients with low-energy intertrochanteric fractures who underwent PFNA fixation and at least a year of follow-up were recruited. Demographics, comorbidities, cognitive status, time to operation, and surgical parameters of the patients were all identified. Excellent and non-excellent outcomes were assessed by Harris Hip Score (HHS) after a one-year follow up. Regression analysis was used to determine the predictors for an excellent functional outcome. A new integrated scoring system (ISSI; Integrate Scoring System in elderly patients with Intertrochanteric fracture) was developed and validated. 450 elderly patients were randomly divided into two cohorts: a development (N = 225) and validation cohorts (N = 225). In this study, age < 85 years, normal weight/overweight, Charlson comorbidity index (CCI) < 6, no cognitive impairment, a modified AO/OTA 31A1.3, time to operation < 6 days, and Tip Apex Distance between 20 and 30 mm were significantly associated with an excellent outcome after PFNA fixation. The range of ISSI score was between 0 to 16 and the cut-off score of 13 was found to have the highest discriminatory power to determine the excellent functional outcome where the area of ROC was 0.85. In regards to the validation cohort, the sensitivity and specificity of ISSI score was 69% and 87%, respectively, and the AUC was 0.81. The ISSI score is effortless and practical for orthopedic surgeons for predicting an outcome after PFNA fixation in elderly patients with an intertrochanteric fracture.