Factors associated with the development of screw cut-out after the fixation of intertrochanteric femoral fractures with a proximal femoral nail

Abstract

Objective: To reveal the factors associated with screw cut-out in the fixation of proximal femur intertrochanteric fractures with a proximal femoral nail (PFN).
 Material and Method: Patients who were diagnosed with proximal femoral intertrochanteric fractures and were being treated and followed up in our hospital between January 2014 and January 2019 were retrospectively analyzed. The hip fracture types of the patients were determined according to the American Foundation/American Orthopedic Trauma Association (AO/OTA) classification. AO/OTA 31-A1, A2 and A3 type fractures were included in the study. Twenty-seven patients with PFN fixation failure and screw cut-out (cut-out group, 11.4%) were compared with 208 patients who had successful osteosynthesis without cut-out (non-cut-out group, 88.6%). Age, gender, affected side, follow-up time, PFN design, tip-apex distance (TAD), calcar-referenced TAD, fracture type, reduction quality, posteromedial support loss, lag screw position, Singh index, and collo-diaphyseal angle (CDA) were compared between the two groups.
 Results: The two groups significantly differed in terms of TAD and calcar-referenced TAD (p = 0.002 and 0.001, respectively). In the evaluation of reduction quality according to the Baumgaertner scale and the Garden alignment index, a significant difference was found between the two groups (p = 0.021 and 0.002, respectively). A significant difference was also observed between the two groups in terms of screw position and posteromedial cortex continuity (p = 0.009 and 0.037, respectively). However, there was no significant difference in relation to age, gender, affected side, CDA, PFN design, and osteoporosis severity.
 Conclusion: Fracture type, poor reduction quality, loss of posteromedial support, TAD, calcar-referenced TAD, and lag screw position were found to be associated factors in the development of screw cut-out. Apart from the type of fracture, these factors that are under the control of the surgeon generally show the importance of anatomical reduction and accurate screw placement.