Investigation of Novel Radiological Parameters to Predict Treatment Failure and Ideal Surgical Interventions in Young Femoral Neck Fractures Treated with Triple Cannulated Screw: A Retrospective Analysis.

Abstract

Treatment failure remains a challenge in young femoral neck fractures treated with triple cannulated screws (TCS). This study aims to identify novel radiological parameters that can predict treatment failure and propose surgical techniques to enhance the success of TCS or aid in selecting alternative methods. We conducted a retrospective analysis of 87 patients who underwent surgery for femoral neck fractures between February 2014 and June 2022, meeting the inclusion criteria. Patients achieving union were categorized as Non-Fail (Group 1), while those experiencing nonunion were categorized as Fail (Group 2). Various demographic and clinical factors were assessed, including age, gender, fracture side, and fracture classification (Garden and Pauwels). Radiological parameters such as fragmentation in the medial cortex, postoperative fracture displacement in the calcar region, collo-diaphyseal angle (CDA) difference (varus/valgus alignment), and several newly defined parameters (modified tip apex distance (m-TAD), tip cortex distance (TCD), upper-lower screw-cortex distance/neck diameter, the calcar screw-cortex distance/neck diameter (Buyukdogan index), and sub-capital area/basocervical area (Dogan index) were evaluated. Patients developing nonunion were studied to establish potential cut-off values based on radiological parameters. Of the patients, 61 were classified as Non-Fail (Group 1) and 26 as Fail (Group 2). Both groups exhibited similar distributions in terms of gender, fracture side, Pauwels classification, and follow-up times (p > 0.05). However, Group 2 had a higher mean age than Group 1 (p = 0.006). There was a significant difference between the two groups in terms of Garden classification (p = 0.0003). Furthermore, postoperative calcar displacement, varus alignment, m-TAD, TCD, upper-lower screw-cortex distance/neck diameter ratio, Buyukdogan index, and Dogan index showed significant differences between the groups (p < 0.05). Conversely, medial calcar fragmentation did not differ significantly between the groups (p > 0.05). The Dogan index (≤ 0.5) can serve as an independent preoperative predictor of treatment failure, aiding in the selection of more effective surgical interventions than TCS. Varus alignment (> 10 degrees), the upper-lower screw-cortex distance to the neck diameter (> 0.45) and Buyukdogan index (> 0.2) are influenced by the surgical technique of TCS application and should be considered to decrease the success of TCS.