Feasibility And Effectiveness Of A Novel Guidewire Aiming Device For The Treatment Of Femoral Neck Fracture With Cannulated Screws

1.BACKGROUNDFemoral neck fracture is a common skeletal system disease in the emergency department.As the number of elderly people increases rapidly,the incidence rate is going higher and higher.Closed reduction and internal fixation with three cannulated screws(CSs)is one of the most common and effective treatments.It’s universally acknowledged that the ‘inverted triangular’ configuration has excellent mechanical strength and stability,where the three screws are parallel to each other on anteroposterior view and the inverted triangular shape on lateral view.Some studies have confirmed that the higher the parallelism of the three screws and the more dispersed the distribution,the higher the mechanical strength and the better the fracture prognosis.Therefore,how to improve the parallelism and dispersion of the three cannulated screws becomes vital to all surgeons.Our team has designed a novel guidewire aiming device(GAD)to improve the accuracy of CSs insertion in femoral neck fracture.This device has simple structure and is easy to use.2.OBJECTIVEThis study consists of two main parts,one is to verify the feasibility of the novel GAD in femoral neck fracture,and another is to evaluate its effectiveness.We will explain the feasibility of the novel GAD by measuring the proximal anatomy of the femur and this work also can provide good reference and experience for later clinical practice.Additionally,we’ll conduct an in vitro randomized controlled trial to explore the effectiveness of the novel GAD compared to the traditional method.3.MATERIALS & METHODS Part one.Feasibility study of the novel GAD for internal fixation of femoral neck fracture with CSs.We randomly retrieved 60 cases of adult hip CT data(30 males and 30 females)from our hospital information system for 3 dimensional(3D)reconstruction.Measurement and analysis of relevant anatomical data were performed on the reconstructed femur.The angle between the anterior baseline and the central axis of the femoral neck was used to determine the geometric relationship of them.These results were used to verify the feasibility of the novel GAD.In addition,we worked out the safe area(SA)of the CSs insertion by projecting the femoral neck along the central axis.After analyzing and summarizing the sample data,the optimal absolute position and relative position of the CSs placement were recorded and calculated.And the usage parameters of the novel GAD were calculated according to data above.Part two.Effectiveness study of the novel GAD for internal fixation of femoral neck fracture with CSs.We made 40 puncture models by assembling 3D printed skin and artificial femur.These models were randomly divided into two groups,one group was the novel GAD assisted group(experimental group)and the other group is traditional fluoroscopy-guided group(control group).The guidewires of CSs were inserted by the above two methods,and the accuracy of the implantation,the number of intraoperative fluoroscopies,puncture attempts,and the operation time were recorded and statistically evaluated.4.RESULTS Part one.(1)Anatomical data of femoral head and neck: 30 female patients had a femoral head diameter of 45.42 ± 2.57 mm.The width of femoral neck were 32.24 ± 2.77 mm in anteriorposterior(AP)radiographs and were 27.01 ± 1.85 mm in lateral radiographs.There was a linear correlation between the diameter of the femoral head and the width of the femoral neck in AP radiographs.A linear correlation between the diameter of the femoral head and the width of the femoral neck in lateral radiographs also was found.The femoral head diameter of 30 male patients was 50.20 ± 1.76 mm;the width of the femoral neck of the AP and lateral radiographs was 35.36 ± 2.39 mm and 29.83 ± 1.68 mm,respectively.There was a linear correlation between the diameter of the femoral head and the width of the femoral neck in AP radiographs.There is no linear correlation between the diameter of the femoral head and the width of the lateral radiographs.(2)Parallelism detection between the anterior baseline and the central axis of the femoral neck: The median of the maximum angle between the anterior baseline and the central axis of the femoral neck in 30 female patients was 6.31 °([IQR] = 3.89°-8.92°)with a 95% confidence interval(CI)of(5.38,8.08)°.In 30 male patients,the median of the maximum angle between the anterior baseline and the central axis of the femoral neck was 7.59°([IQR] =6.00°-12.81°),95% CI =(7.52,10.38)°.(3)Analysis of the SA for CSs placements of the femoral neck: The femoral neck SA of the 30 female patients and 30 male patients was roughly similar in shape,and it was a near elliptical shape with a flat front.(4)Optimal placement positions: The position of the 1,2,and 3 screws in 30 female patients was 28.72 ± 2.76 mm(89.02% ± 2.66%),8.76 ± 1.80 mm(27.10% ± 4.65%),and 7.28 ± 1.48 mm(22.58% ± 3.95%)from the front boundary and was 16.46 ± 3.01 mm(60.87% ± 9.94%),21.62 ± 2.21 mm(79.98% ± 5.54%),3.65 ± 0.27 cm(13.56% ± 1.36)%)from the upper boundary.The position of the 1,2,and 3 screws in 30 male patients was 32.57 ± 2.36 mm(92.12% ± 3.00%),9.24 ± 2.21 mm(26.03% ± 5.62%),and 7.65 ± 1.83 mm(21.77% ± 5.51%)from the front boundary and was 18.19 ± 4.00mm(60.90% ± 12.70%),24.32 ± 2.63mm(81.47% ± 6.75%),and 3.59 ± 0.48mm(12.04% ± 1.63%)from the upper boundary.Part two.In both groups,the guidewires did not pierce the femoral neck cortex.The accuracy of CSs guidewire placement in GAD group was higher than in the conventional group: there was no significant difference in parallelism score,19.7 ± 2.8 points vs 20.3 ± 2.5 points(P =0.583),but there was significant difference in the coverage area of the three guidewire,72.9±11.7mm2 vs 55.3 ± 9.6mm2(P <0.0005).In addition,The number of fluoroscopies in the GAD group was less than that in the conventional surgery group,14.5±2.5 times vs 24.0 ± 5.5 times(P <0.0005).And the number of puncture attempts in the GAD group was less than that in the conventional group,5.2 ± 1.5 times vs 8.2 ± 3.0 times(P <0.0005).The experiment also showed that there was no significant difference between the operation time of the GAD group and one of the conventional group,25.4 ± 4.0min vs 22.9 ± 4.4min(P = 0.068).5.CONCLUSIONS(1)The study suggests that the SA for CSs placements in femoral neck fracture is a near elliptical shape with a flat front and the anterior baseline is approximately parallel to the central axis of the femoral neck,which conform to the design basis of the novel GAD.The study also provides reference values for the position of the three CSs by data measurement and analysis.Additionally,the reference value of the adjustment parameters of the three CSs when using the novel GAD is obtained by data conversion..(2)The in vitro model experiment suggests that the GAD is helpful to the implantations of CSs in femoral neck fracture.It can reduce the number of intraoperative fluoroscopies,the puncture attempts,and improve the accuracy of CSs placement.At the same time,the operation time does not increase.