الفهرس 
Title : A novel parameter for lag screw placement in patients with proximal femur fractures
ContantsOnly 14 pages are availabe for public view
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Abstract
Pertrochanteric fractures are one of the most common injuries in the elderly. Dynamic hip screw is the most common implant used for managing the stable patterns of these injuries. Lag screw cut out is a serious complication that has a big influence on patient morbidity and mortality. Several parameters, especially lag screw position within the femoral head, have been acknowledged to be related with lag screw cut out. The current parameters used to evaluate the lag screw position within the femoral head do not provide a full idea about the lag screw insertion depth and direction at the same time. We propose a novel parameter for measuring the lag screw position within the femoral head and hypothesise that it could improve the sensitivity and specificity for detecting lag screw cut out in these injuries.
Patients and Methods: A retrospective study was conducted for hip fracture entries in the period from Jan 2018 - Dec 2021. 921 subjects with hip fractures were evaluated against the inclusion criteria, of which 109 patients deemed eligible. A receiver operating characteristic curve (ROC) was used to evaluate the sensitivity and specificity of different parameters used to assess the lag screw position within the femoral head. The novel parameter was measured based on the sum of the value of twolimbs in the AP view and the usual TAD in the lateral view. We propose an acronym for the novel parameter as Cairo University Trochanteric Cut Out indeX (CUTCOX).
Results: The Cleveland zone, Parker’s ratio in the AP, reduction quality, the TAD, the Cal TAD, the ABA and the novel parameter were statistically associated with lag screw cut out. The novel parameter showed the highest combined sensitivity 100 % and specificity 94.4% of lag screw cut out at a cut off value 25 mm with a P value < 0.001. The TAD showed the second highest sensitivity 100% and specificity 92.1% of lag screw cut out at a cut off value 25 mm.
Conclusion: The novel parameter shows the highest combined sensitivity and specificity among other parameters predicting lag screw failure in patients with pertrochanteric hip fractures managed with DHS. Hence, its use as a predictive measure for prevention of lag screw cut out is recommended.