Description of a minimally invasive technique with a modified instrument for the osteosynthesis of proximal femoral fractures using the standard DHS and case series

Introduction: the number of hip fractures is estimated to increase from 1.66 million in 1990 to 6.26 million by 2050. Internal fixation is the most common surgical treatment for intertrochanteric fractures. Objectives: the objective of the present research is to describe a minimally invasive technique with a modified instrument for the treatment of stable proximal femoral trochanteric fractures using the standard DHS, classified as Tronzo types 1 and 2 (AO 31A1.2), and presenting a case series. Methods: a case was selected to present the technique. Patients operated by this technique undergo a clinical evaluation and preoperative preparation as routine. The criteria for inclusion in the study were the presence of stable fracture of the proximal femur verified by two hip specialist orthopedists, and operated by the minimally invasive technique with a modified instrument using a standard DHS. Exclusion criteria were cases of patients operated for unstable fractures, and the use of other surgical techniques. A case series of 98 patients was performed and discussed. Results: minimally invasive technique with a modified instrument using the standard DHS device can reduce bleeding, it decreases soft tissue injuries, surgical time, and hospital stay, as any other MIPO procedures. Ninety-eight patients underwent the operation (Tronzo types I and II), 59 female and 39 male, ages from 50 to 85 years old. Immediate post-operative complications were shortening of the lower limb, loss of fracture reduction, and death by clinical complications. Conclusion: the present study describes a minimally invasive surgical technique using a modified instrument to perform proximal femoral osteosynthesis for stable trochanteric fractures, using the standard DHS.


INTRODUCTION
T he risk of hip fracture is high, ranging from 40% to 50% in women over 60, and 13% to 22% in men.
With life expectancy increasing worldwide, and due to these demographic changes, the number of hip fractures is estimated to increase from 1.66 million in 1990 to 6.26 million by 2050 1,2 . The estimated annual cost of treating these fractures is enormous and represents a significant burden on any health system 1 .
Internal fixation is the most common surgical treatment for intertrochanteric fractures 3

MATERIAL AND METHODS
The present study describes a minimally invasive technique using a modified instrument for

DESCRIPTION OF THE TECHNIQUE
As the traditional technique, the surgical procedure begins with the patient in supine position on a traction table. The fracture is reduced with traction and internal rotation ( Figure 1A, 1B). A fluoroscopy assesses the prepositioning of the guide wire over the skin in the fractured hip region, following the cephalo-medullary angle, and the location of the guide wire laterally in the hip is defined ( Figure 1C). Then a 4 cm incision is made observing the guide wire outlet (1cm proximal and 3cm distal) ( Figure 1D). Skin and subcutaneous tissue, fascia lata and musculature are opened in the stretch. Then the proposed instrument, a disassembled 135-degree boot guide is passed (Figures 1E,F,G,H,I), mounting the device in the proximal femur ( Figures 1F,J). The guide wire is introduced ( Figure 1K,L,M). Its positioning is evaluated according to the traditional technique, centered on the anteroposterior and lateral in the x-rays views or slightly below and posterior to avoid the cutout ( Figure 1L,M).
The new proposed instrument, the 135 degrees positioner is subtly removed by pulling it out and disassembling it, once the wire is positioned as recommended by the literature (Figure 1N). The drilling is performed as usual and the DHS screw is inserted ( Figure   1O), respecting the TAD index. A special instrument, a DHS plate slider ( Figure 1P) is used in this step. After inserting the DHS plate in reverse ( Figure 1Q), you must rotate it by 180 degrees and hold it (plate) with your finger ( Figure 1R,S). The plate slider has a tune that slides the DHS plate, making it easy to insert into the Richards screw ( Figure 1P). The screw-like fits into the instrument and facilitates the manipulation in all directions ( Figure   1T,U,V). The skin is then pulled down and the cortical screws are inserted ( Figure 1W). The fluoroscopy is used to perform the general revision, and then the fascia lata, subcutaneous and skin are closed. Please note the small incision performed with the technique (Figure 1X).

Tips and tricks
Increased difficulty must be considered for the introduction of the guide wire in patients with soft tissue stiffness, scars, and previous trauma, due to the limitation in handling these structures. It is also important to remember that excess of internal or external rotation of the lower limb can cause tension to the muscles, and consequently make the surgical procedure difficult.
Finally, note that the more laterally is the insertion of the Irigoyen Description of a minimally invasive technique with a modified instrument for the osteosynthesis of proximal femoral fractures using the standard DHS and case series Richard screw the more hinder is the plate positioning.
We suggest leaving 2 to 3mm of screw outside the lateral cortex of the femur.

Case series
Ninety-eight patients underwent this operation