## 3 Key Points of the Surgical Technique  
Before describing the surgical procedure, the philosophy of our new technique must be understood. Because of the eccentric mechanical axis of the femur, high bending shear forces in subtrochanterior injuries cause the proximal fragment to deviate in varus. Thus, high bending stress is created medially and tensile forces laterally, increasing the strain \begin{table}
\begin{tabular}{l c c c c c c} \hline
**PATIENTS** & **1** & **2** & **3** & **4** & **5** & **Mean** \\ \hline Age * & 34 & 54 & 85 & 69 & 78 & 64 (34–85) \\ \hline Sex & Male & Female & Female & Female & Female & – \\ \hline Time from fracture & & & & & & \\ to nonunion & 40 & 12 & 12 & 10 & 13 & 17.4 (40–10) \\ diagnosis & (months) * & & & & & \\ \hline Affected hip & Left & Left & Right & Right & Right & – \\ \hline Injury mechanism & Vehicle & & & & & \\ accident & Simple fall & Simple fall & Simple fall & Simple fall & – \\ \hline Previous implant & \begin{tabular}{c} Long intramedullary \\ nail \$ \\ \end{tabular} & \begin{tabular}{c} Short intramedullary \\ mainland \\ nail \\ \end{tabular} & \begin{tabular}{c} Short intramedullary \\ mainland \\ \end{tabular} & \begin{tabular}{c} Short intramedullary \\ mainland \\ \end{tabular} & \begin{tabular}{c} Long intramedullary \\ mainland \\ \end{tabular} & \
\begin{tabular}{c} Long intramedullary \\ mainland \\ \end{tabular} &
\begin{tabular}{c} – \\ mainland \\ \end{tabular} \\ \hline Femoral neck angle & & & & & & \\ pre-surgery * & & & & & \\ \hline Pre-surgery offset & & & & & \\ (mm) * & & & & & \\ \hline Vertical distance & & & & & \\ nonunion-head & 57 & 43 & 32 & 46 & 40 & 43.6 (32–57) \\ pre-surgery (mm) * & & & & & \\ \hline Limb length & & & & & \\ discrepancy (mm) * & & & & & \\ \hline Harris Hip Score & & & & & \\ pre-surgery * & & & & & \\ \hline \end{tabular}  
*: Parameters were measured and presented with the mean and range in parenthesis. *: First-generation nail. *: Third-generation nail (cephalo-medullary nail).  
\end{table} 
Table 1: Baseline demographics of the patients and preoperative radiologic and functional parameters. at the fracture nonunion (Figure 1A). After the decompaction of the fragments (without removing the fibrous tissue from the nonunion site), the head screw is introduced into the undamaged lateral trochanteric cortex of the proximal fragment (Figure 1B). Posteriorly, the plate is applied to the head screw and secured to the shaft to achieve valigation of the proximal fragment (Figure 1C). Over-valgization of the proximal fragment is the key point of our novel technique. It implies a verticalization of the proximal fragment. This way, the lateral cortex is positioned against the medial area of the distal fragment, producing a lateralization of the shaft (Figure 1C). The DHS will bear strong weight-bearing loads, and due to its dynamic behavior, a progressive medialization of the previously lateralized shaft will occur, resulting in progressive compaction between fragments. Thus, the main drawback of the DHS, which is the medialization of the diaphysis, is now one of the keys to the technique's success (Figure 1D). This zone of bone contact is subjected to strong loads, creating firm, progressive contact between the fragments. It will behave as a true bone stop that prevents excessive medialization of the diaphysis. Due to the verticalization of the proximal fragment, load transmission occurs more vertically, which is the dominant form of transmission in this subtrochanteric zone. Moreover, due to the overcorrection of the hip valgus, which shifts the mechanical axis of the femur laterally, shear forces are transformed into compressive forces. Thus, even through this small area, a powerful bony bridge is created that adequately conducts the loads to the diaphysis and marks the beginning of an early and significant bony callus.