Predicting cut-out in intertrochanteric fractures fixed with cephalomedullary nails: the role of tip-to-apex distance referenced to calcar (calTAD)--A retrospective analysis of 158 cases

Abstract

Introduction: The optimal positioning of the cephalic screw in intertrochanteric fractures (ITFs) is crucial for minimizing the risk of cut-out. This study assesses the predictive value of the tip-to-apex distance (TAD) and tip-to-apex distance referenced to calcar (calTAD) for cut-outs in patients undergoing fixation with cephalomedullary nails.

Method: We analyzed 158 consecutive patients aged over 65 years (mean 83.6 ± 15.9) with intertrochanteric hip fractures who underwent cephalomedullary nailing between January 2016 and July 2022. Receiver operating characteristic (ROC) curves were used to determine the optimal cut-off points for TAD and calTAD. Uni- and multivariate logistic regression analyses were conducted to identify independent predictors of cut-out, considering demographic data, comorbidities, fracture type (AO/OTA), reduction quality (according to Baumgartner classification), TAD, and calTAD.

Results: Cut-out occurred in 12 patients (7.5%). ROC analysis identified 18.99 mm as the optimal cut-off for TAD (sensitivity 83.3%, specificity 63.7%; area under the curve-AUC- 0.703, p = 0.009) and 24.95 mm for calTAD (sensitivity 100%, specificity 82.9%, AUC = 0.906, p = < 0.0001). Univariate analysis revealed no significant differences in demographics, fracture type, or reduction quality between patients with and without cut-outs. Multivariate analysis identified calTAD > 24.95 mm as the only independent predictor of cut-out, with an Odds ratio of 24.62 (95% Confidence Interval 27.61-68.92, p = 0.001).

Conclusion: Our findings suggest that calTAD is a helpful measure for predicting cut-outs in intertrochanteric fracture fixation using cephalomedullary nails in the context of good fracture reduction. Surgeons should aim to keep calTAD values below 24.95 mm to reduce the risk of cut-out, as values above this threshold significantly increase the risk.

Keywords: Cephalomedullary nailing; Intertrochanteric fracture; Lag screw position; Tip-apex distance (TAD); Tip-apex distance referenced to calcar (calTAD).