Risk factors for implant failure of PFNA–II in the treatment of intertrochanteric fractures (AO/OTA 31 A1 and A2)

Intertrochanteric fractures are common in the elderly, with PFNA being the primary treatment. The shorter PFNA-II is frequently used in Asian populations, but its failure risk factors remain unclear. This study aims to explore these factors to guide clinical treatment. A retrospective study was conducted on 693 intertrochanteric fracture patients treated with PFNA-II. Patients were divided into two groups based on implant failure. Reduction quality, continuity of the medial femoral cortex, nail length, and tip apex distance (TAD) were analyzed to determine risk factors. A total of 466 patients were enrolled, with an average age of 83 years old. There were 24 patients with implant failure. There was no significant difference in demographic index between the two groups. After propensity score matching and multivariate logistic regression analysis, there were statistically significant differences in reduction quality and continuity of the medial femoral cortex between the two groups. Poor reduction quality significantly increased the risk of implant failure by 22.2 times, while discontinuity of the medial femoral cortex increased this risk by 12.1 times. Poor reduction quality and medial femoral cortex discontinuity are key risk factors for implant failure in intertrochanteric fractures treated with short PFNA-II, increasing failure risk by 22.2 and 12.1 times respectively. Anatomic reduction and medial support reconstruction are crucial for successful outcomes.