A Novel Device for Accurate Guide wire Placement in Cannulated Screw Fixation of Femoral Neck Fracture:A Pilot Study

Background: Accurate placement of cannulated screws is the key to stable xation of the femoral neck fracture. A novel device was developed to improve the accuracy of screw placement. Methods: 20 synthetic femoral bones were divided into conventional technique group and the experimental group. Three Kirschner wire were inserted into the femoral neck fracture by conventional technique or by the simple guide device. The operative time, total drilling times and uoroscopic frequency were evaluated. Results: By using the guide device, the uoroscopy and operation time of the experimental group were shorter that of the conventional method. The total drilling times with the simple guide device were signicantly lower than the conventional technique group. Conclusions: This device can help trauma surgeons shorten the surgical time and reduce radiation exposure time. The use of this guide device can make screw xation for femoral neck fracture easier.


Background
Femoral neck fracture is a common hip fracture in orthopedics. Internal xation is preferred for femoral neck fracture in young people and non-displaced femoral neck fracture in elderly people with good physical condition 1,2 . Cannulated screws has been an accepted implant among several implants which have been used for femoral neck fracture 3,4,5 . Placing three cannulated screws in parallel with the inverted triangle can provide better biomechanical stability 6 . However, it is not easy for the surgeons to place screws at the right position. Accurately to insert guide wires accounts for a signi cant proportion of the total uoroscopy and operative time.
In this study, the authors designed a novel device for accurate placement of guide wires in cannulated screw xation of femoral neck fracture. The purpose of this study was to demonstrate the effectiveness of the guide device. In the conventional technique group, a guidewire was placed along the anterior femoral neck as a reference. The rst Kirschner wire was inserted to femoral neck manually. Fluoroscopic imaging was performed and once it was in the inferocentral part of femoral neck, use a parallel guide to place the posterosuperior and anterosuperior Kirschner wire.

Structure of the device
In the experimental group, the guide device was sutured on the lateral side of the thigh and the Kirschner

Statistical Analysis
This was carried out using SPSS18.0 software (SPSS Inc., Chicago IIIiosi) using chi-squared testing. The level of signi cance was set as a p-value<0.05.

Results
The operative time with the novel device were signi cantly lower than the operation with the conventional technique (p 0.05). The uoroscopic frequency and total drilling times were also signi cantly lower in the operation with the novel device (p 0.001 ).

Discussion
Closed reduction and internal xation have become the standard methods for the treatment of femoral neck fractures in patients 60 years of age or younger. Fixation with three parallel cannulated screws placed in an inverted triangle con guration, is a common method for femoral neck fracture 7 . If complication didn't occur, the patient can resume normal activities. The inverted triangle is effective in reducing the rate of nonunion and implant failure 8 . However, accurate guide wire placement necessitates high requirement for the surgeon and requires more uoroscopic and operative time. So, we developed this device to make it easier.
The conventional method of screw placement for femoral neck fractures is mainly performed by surgeons with experience under fluoroscopic monitoring. During the screw xation of femoral neck fracture with closed reduction, the femoral neck was not exposed and the desired position was not easily obtained due to the lack of necessary reference during the placement of the rst guide needle, which often requires multiple drilling for success. Multiple drilling not only resulted in prolonged operation time, increased tissue damage, and increased doctor-patient exposure time to the X-ray radiation, but also resulted in unstable fracture xation due to more or less osteoporosis in the femoral neck of most patients 9 .
By using the guide device, the uoroscopy and operation time of the experimental group were shorter that of the conventional method. The most important thing is to successfully insert the guide wires in the femoral neck at one time. The femoral cortex was not drilled frequently.
The guide device is easy to operate. It works like inserting the spiral blade in the proximal femoral nail anti

Conclusions
This guide device can signi cantly improve the accuracy of injection, reduce tissue damage, shorten the operation time and reduce the amount of X-ray radiation, and has less dependence on the operator's experience. The use of this device can make percutaneous compression hollow screw xation for femoral neck fracture easier. Figure 1 Picture of the guide device. (A) aiming component consists of damping (1), a rod (2) and two meshes (3), which were welded on the two opposite sides of the damping. (B) xation component: two stainless steel buckle(4), which has a hole and locking knob, are welded to a small steel plate (5).

Figure 2
The guide device was xed on the surface of the skin. The three Kirschner wire through the pipe was inserted onto the surface of the femur. (A: Anterior view, B: lateral view).