A Simple and Effective Guide Device for Femoral Neck Fracture Fixed With Cannulated Screw Fixation

Background: Accurate placement of cannulated screws is the key to stable xation of the femoral neck fracture. A simple guide device was developed to improve the accuracy of screw placement. Methods: 40 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: The use of this guide device can make screw xation for femoral neck fracture easier. This is helpful for an inexperienced hand.


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 the common one 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 screws accounts for a signi cant proportion of the total uoroscopy and operative time.
In this study, the authors designed a simple and effective guide device for femoral neck fracture cannulated screw xation to make the xation easier. 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 inferocentra part of femoral neck, use a parallel guide to place the posterosuperior and anterosuperior Kirschner wire.
In the experimental group, the guide device was xed on the lateral side of the proximal femur and insert the Kirschner wire through the sleeve onto the lateral femur cortex (

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.

Result
The results are presented in Table 1. The operative time and total drilling times with the simple guide device were signi cantly lower than the operation with the conventional technique (p 0.05). The uoroscopic frequency was also signi cantly lower in the operation with the new drill guide (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 screw placement necessitates high requirement for the surgeon and requires more uoroscopic and operative time. So, we developed this simple and effective guide device to make the xation with screw easier.
The conventional method of screw placement for femoral neck fractures is mainly performed by surgeons with experience under fluoroscopic monitoring. During the internal xation of femoral neck fracture with closed reduction, the femoral neck is not exposed and the desired position is 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 wire in the femoral neck at one time. The femoral cortex is not drilled frequently.
The guide device is easy to operate. It works like inserting the spiral blade in the proximal femoral nail anti-rotation system. When The regulating device is xed on the lateral side of the thigh between the anterior and posterior femur cortex, the sleeve is at a 45degree angle to the lateral cortex in the anteroposterior view. The angle of anteversion can be adjusted by rotating the rod in steel buckle. Anteroposterior and lateral uoroscopic images were acquired. The trajectory of the Kirschner wire in the femoral neck is judged according to the extension of image of Kirschner wire on the c-arm uoroscope.
Once the Kirschner wire is in right place, the Kirschner wire was drilled into the femoral neck. The rst Kirschner wire was successfully inserted into the femoral neck at one time. Then the other two Kirschner wire were drilled by the parallel aiming device.
Other researchers have developed guides to accurately place Kirschner wires. Yin et al. demonstrated a novel guidewire aiming device to improve the accuracy of guidewire lnsertion 10 . However, the operation was complicated. The navigation systems could improve accuracy 11,12,13 , but the higher costs of the special instruments and increased radiation and operative time limited their clinical use 14 .
In conclusion, 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 guide can make percutaneous compression hollow screw xation for femoral neck fracture easier.
We believe this guide device can help to promote screw xation technique in third world countries. This is helpful for an inexperienced hand.  The guide device was xed on the surface of the skin. The rst Kirschner wire through the sleeve was inserted onto the surface of femur.