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A new adjustable parallel drill guide for internal fixation of femoral neck fracture: a developmental and experimental study
© Yuenyongviwat et al. 2016
Received: 27 May 2015
Accepted: 7 December 2015
Published: 11 January 2016
Internal fixation is one treatment for femoral neck fracture. Some devices and techniques reported improved accuracy and decreased fluoroscopic time. However, these are not widely used nowadays due to the lack of available special instruments and techniques. To improve the surgical procedure, the authors designed a new adjustable drill guide and tested the efficacy of the device.
The authors developed a new adjustable drill guide for cannulated screw guide wire insertion for multiple screw fixation. Eight orthopaedic surgeons performed the experimental study to evaluate the efficacy of this device. Each surgeon performed guide wire insertion for multiple screw fixation in six synthetic femurs: three times with the new device and three times with the conventional technique. The fluoroscopic time, operative time and surgeon satisfaction were evaluated.
In the operations with the new adjustable drill guide, the fluoroscopic and operative times were significantly lower than the operations with the conventional technique (p < 0.05). The mean score for the level of satisfaction of this device was also statistically significantly better (p = 0.02) than the conventional technique.
The fluoroscopic and operative times with the new adjustable drill guide were reduced for multiple screw fixation of femoral neck fracture and the satisfaction of the surgeons was good.
KeywordsFemoral neck fracture Drill guide Internal fixation
Internal fixation is the standard treatment of femoral neck fracture in young patients and non-displaced or impacted femoral neck fracture in the elderly [1, 2]. The key success factor of this fixation depends on the quality of the bone, number of screws, and screw position in the femoral neck [3, 4]. Parallel three-screw fixation is better than two-screw fixation because three-screw fixation has greater resistance to load and less fracture displacement . The other factor is the position of the screws. A greater separation between the screws results in better fixation stability . In addition, each screw must be inserted parallel to each other and form an inverted equilateral triangle configuration . The need for very precise screw placement requires a meticulous surgical technique that usually requires a prolonged operative time and the surgeon has to deal with high radiation exposure.
Recently, several devices and techniques were developed to improve the accuracy and minimize fluoroscopic time. Computer-based navigation techniques [8–10] using a cannulated screw as the drill guide  were reported to reduce radiation time and improve accuracy. However, these techniques are not widely used because of the limitation on the higher costs of the special instruments.
Our group designed a new adjustable drill guide device. The aim of this study was to compare the fluoroscopic time, operative time, and surgeon satisfaction of the new device with the conventional technique in cannulated guide wire insertion for multiple screw fixation of femoral neck fractures.
Design and development
The concept for development of this drill guide was based on the drill guide helping the surgeon insert the cannulated guide wire with an easily adjustable separation distance from the reference guide wire and produce good stability during insertion of the cannulated guide wire.
Simulated operation testing
This study was approved by the Ethics Committee and Institutional Review Board of the Faculty of Medicine at Prince of Songkla University, Songkhla, Thailand. This study was conducted in synthetic bones and not related to human subjects. So, an informed consent was unnecessary according to institutional regulations.
The experimental study evaluated the efficacy of the new drill guide compared to the conventional technique. The intraoperative setting was a simulated multiple screw fixation in femoral neck fracture with the patient in the supine position. The synthetic femoral bone made of foam cortical shell with cancellous inner material (Sawbones™, Pacific Research Laboratories, Inc., Vashon, Washington, USA) was placed on the operative table and fixed with a synthetic bone holder. The synthetic bone was covered with sponges to simulate the soft tissue compartment.
Eight orthopaedic surgeons were included in this study. They were given instructions and then practiced the technique to use this new drill guide. Each surgeon performed cannulated guide wire insertion for multiple screw fixation in six femurs using three guide wires for three-screw cannulated screw fixation in each femur. They performed the operation three times with the new drill guide and three times with the conventional technique. In the conventional technique group, guide wires were inserted using a standard parallel wire guide (Synthes 312.71 Parallel Wire Guide, Synthes, Paoli, Pennsylvania, USA) and protection sleeve. The operations were performed under C-arm fluoroscopy (Philips BV Libra, Philips Medical Systems North America Co., Bothell, Washington, USA) in the same operative theater environment.
The statistical analysis was performed using R software version 3.1.0 (R Foundation). In order to compare fluoroscopic time and operative time, the differences between the groups used the Wilcoxon signed-rank test. The student t-test was used for comparison of satisfaction scores. Statistical significance was considered when P was less than 0.05.
A statistical power analysis was performed for sample size estimation based on data from a previous study . To detect a 10 % difference in fluoroscopic time with a power set to 0.9 and a significance level set to 0.05, nine samples per group were required.
Fluoroscopic and operative times of the operations
New device (24)
Fluoroscopic time (seconds)
Operative time (minutes)
Femoral neck fracture is a fracture that produces significant morbidity and mortality. The majority of fractures occur in the elderly from low-energy trauma and a low incidence of fractures occurs in younger patients from high-energy trauma . There are two main options for treatment of femoral neck fracture: internal fixation and arthroplasty .
Multiple screw fixation is the choice of treatment for non-displacement, impacted fracture in the elderly and also displaced fracture in young patients . Screw position and configuration are the crucial parts of a successful outcome. Selvan reported a biomechanical study of configuration of multiple screws for the fixation of intracapsular hip fractures. The study showed that triangular configurations of three parallel screws could resist a higher load than other screw configurations . Due to the high precision needed for screw placement, this operation usually requires a long operative time and high radiation exposure to the surgeon.
There were reports of new surgical techniques and devices to improve the operating procedure and decrease the radiation exposure and operative times. Liebergall et al. reported a comparison study between a computer-based navigation technique and the conventional fluoroscopy technique. The results showed that the navigation group had better screw positions and had a tendency for a fewer number of reoperations and overall complications . Kendoff et al. also reported results of an integration of the parallel drill guide and navigation module compared with the conventional technique. The study found a reduction of radiation time in the navigation group but the operative time increased . Another report showed a significant reduction in operative time by using a cannulated screw as a drill guide and sleeve compared with the conventional technique .
This present study demonstrated the advantages of the new adjustable drill guide in comparison with the conventional technique. Since the distance for drilling is easily adjustable with the new stable drill guide, high accuracy for parallel drilling can be maintained. The spikes at the tip of the sleeve also prevent drill guide slippage as the drill starts through the femoral cortex. The new drill guide has a low learning curve to become familiar with the device and most surgeons in this study were satisfied with this new device. This new adjustable drill guide might also be applied to other operations which require parallel drilling from a reference point such as odontoid screw fixation or anti-rotational screw for dynamic hip screw fixation [11, 15].
In this experimental study, the new adjustable drill guide reduced fluoroscopic and operative times in multiple screw fixation for femoral neck fracture with good surgeon satisfaction. However, further clinical studies should be conducted to evaluate the efficacy of this new device in clinical practice.
The study was funded by Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand. The authors wish to thank Glenn Shingledecker for his assistance in proofreading the English of this report.
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