Study on the Effect of Removing the Slide Wire Screw on Locking Plate by Nail Groove Reconstruction Method

11 Background: This paper is to describe and evaluate the nail groove reconstruction 12 method in removing slide wire screw on locking plate. Then compare the method with 13 tungsten steel drilling nail method, to explore a new method of removing slide wire 14 screw on locking plate. 15 Method: A total of 1254 patients with removal fracture internal fixation devices 16 were collected from the Affiliated Hospital of Hangzhou Normal University from July 17 2015 to September 2021, of which 62 cases met the inclusion and exclusion criteria. 18 All patients were randomly divided into the experimental group and the control group. 19 31 people per group. There were 19 males and 12 females in the experimental group, 20 the age of patients was 35.68 ± 11.70years; while 18 males and 13 females in the 21 control group, the age of patients was 36.27 ± 10.37years. Nail groove reconstruction method was used in the experimental group, and the tungsten steel drilling nail 1 method was used in the control group. Collect and count surgical-related indicators, 2 the data of two groups were compared and analyzed from four aspects: intraoperative 3 blood loss, operation time, incision healing time and limb function recovery time. 4 Result: All slide wire screws were removed successfully, and all patients had no 5 serious postoperative complications such as internal fixation retention and 6 neurovascular injury. The experimental group was better than the control group in the 7 following three aspects: the amount of intraoperative blood loss, the operative time ， 8 the recovery time of limb function, and the differences were statistically significant(p 9 < 0.05). There was no significant difference in incision healing time between the two 10 groups. 11 Conclusion: The nail groove reconstruction method has less damage to the bone 12 and soft tissue, less intraoperative blood loss, shorter operation time, and faster 13 postoperative recovery of limb function. The nail groove reconstruction method is a 14 simple and effective method, it has obvious advantages compared with the traditional 15 method. 16

method was used in the experimental group, and the tungsten steel drilling nail 1 method was used in the control group. Collect and count surgical-related indicators, 2 the data of two groups were compared and analyzed from four aspects: intraoperative 3 blood loss, operation time, incision healing time and limb function recovery time. Result: All slide wire screws were removed successfully, and all patients had no 5 serious postoperative complications such as internal fixation retention and 6 neurovascular injury. The experimental group was better than the control group in the 7 following three aspects: the amount of intraoperative blood loss, the operative time， 8 the recovery time of limb function, and the differences were statistically significant(p 9 < 0.05). There was no significant difference in incision healing time between the two 10 groups. system not only provides strong support for the fracture, but also disperses the stress, 5 which provides a good biomechanical environment for postoperative functional 6 exercise. So that the limb's function can be better restored. Most of the internal 7 fixation need to be removed after fracture healing, especially those related to 8 intra-articular fractures. The studies show that the pain is relieved and the function is 9 significantly improved after removing internal fixation of ankle joint and knee joint 10 (1-3). Although the removal of internal fixation device is a simple operation, 11 according to statistics, the incidence of complications is as high as 20%, among which 12 the difficulty caused by slide wire screws is the most common and most troublesome 13 problem for clinicians (4-6) . When screw slipping occurs during operation, improper 14 treatment may cause a series of iatrogenic injuries, including postoperative fracture, 15 neurovascular injury, and increase the probability of postoperative infection (7). At 16 present, there are the following common methods are used to remove slide wire 17 screws: ①Rotating plate loosening screw method, ②Bending or shearing steel plate 18 method, ③Cutting off the end of screws method, ④Groove-changing method.

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However, these methods have some limitations and shortcomings, such as they can't 20 be used in the case of two or more adjacent screws sliding wire, and a lot of metal 21 debris will be produced in the process of screw extraction. In response to the dilemma 22 in the clinic, inspired by the groove-changing method, we designed a new method, 1 called nail groove reconstruction method. 2 We aim the large-sized screwdriver at the groove of the slide wire screw and slowly 3 knock it in along the direction of the screw to make a new torx groove in the tail of 4 the screw. Keep the screwdriver always in the direction of the screw during the 5 tapping process. When the screwdriver is completely in the groove, turn the 6 screwdriver to remove the slide wire screw. This method can take out multiple slide 7 wire screws on any position of the plate. In this study, the nail groove reconstruction 8 method was compared with the traditional method, and its clinical effect was 9 evaluated from the aspects of incision healing time, operation time, blood loss,    There were 19 males and 12 females in the experimental group, the age of patients 5 was 35.68 ± 11.70years, the time after internal fixation was 13.90 ± 1.89. 6 Experimental group contained 38 screws, including 4 screws with 5mm diameter and 7 34 screws with 3.5mm diameter. Besides, There were 18 males and 13 females in the 8 control group, the age of patients was 36.27±10.37, the time after internal fixation 9 was 14.10±2.12. Control group contained 40 screws, including 5 screws with 5mm 10 diameter and 35 screws with 3.5mm diameter. All slide wire screws were hexagonal 11 screws. There was no significant difference between the two groups on the patients' 12 basic information. (including gender, age, time after internal fixation, type and 13 number of slide wire screws)( p > 0.05, Table 1).   5 We cut the skin along the original incision, separated the soft tissue to fully expose the 6 plate and screw, and removed the soft tissue and hyperplastic callus embedded around 7 plate and screws. We needed select a matching screwdriver, fully inserted it into the 8 groove of the screw, and removed the screws one by one. If there was screw difficult 9 to remove, put it on hold and removed the easy screw first. Then we tried to remove 10 the difficult screw with T-handle's screwdriver again. When the screw slid, different 11 screw extraction methods were adopted according to the different groups.  Nail groove reconstruction method: The nail groove reconstruction method was 19 used in the experimental group. The larger toxr screwdriver was knocked into the 20 groove of the slide wire screw. When the larger toxr screwdriver was absolutely 21 advanced into the screw groove, a new torx groove was reconstructed. Then we could 22 turn the screwdriver to remove the screw slowly. There were a few points for attention: 1 ①Keep the screwdriver in the same direction as the screw; ②Be gentle and slow in 2 the process of knocking; ③Pay attention to the metal debris in the process. The 3 screwdriver used during the operation is shown in Figure 1, and the typical case is 4 shown in Figure 2-5.    The difference between two groups was compared by the independent sample t-test.

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The Chi-square test was performed for the qualitative data. Statistical significance 9 was set at P value less than 0.05.

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A total of 62 patients were included in this study, 31 patients per group. The  The recovery time of limb function in the experimental group was 19.52±3.04, the 20 control group was 29.16±4.39. There was significant difference between the two 21 groups (p < 0.05) (Details in Table 2 and Figure 6).  removal of internal fixation device is the low-level operation, but when the screw is 10 slippery, the difficulty of the operation is greatly increased. When it is difficult to 11 remove plates and screws, improper removal will cause complications such as 12 re-fracture, neurovascular injury, retention of internal fixation and so on (7) . There are 13 so many reasons for screw slipping, which can be summarized three aspects: Patient have greater biomechanical strength in conjunction with the screws, so slide wire is 2 easy to occur when removed (9,10). Several studies have shown that the 3.5mm 3 screw is more difficult to be removed than 4.5mm and 5.0mm screw (5). Statistics 4 show that the rate of 3.5mm screw slide wire is 10.7%, while that of 5.0mm screw is 5 2.0%. The difference is statistically significant. The main reason is that the groove of surface polishing is easier to remove (7). The application of locking plate 8 significantly increases the incidence of slide wire screw (5,6). The locking plate 9 commonly is made by titanium alloy and stainless steel. And the biological 10 characteristic of titanium alloy is more consistent with the bone, but the hardness is 11 low, which can easily lead to screw deformation and wear when encountered with 12 resistance (4,5,8,11). And the cold welding effect will occur between the titanium 13 alloy plate and screw, so titanium alloy screw is most likely to slide wire (12,13). 3. 14 Latrogenic factors. The irregular operation of the surgeon is an important reason 15 leading to slide wire screw, including：①The drill bit didn't match the screw; ②The 16 sight was not used when drilling the screw was not placed in the direction of the 17 screw path, and no torque limiting screwdriver was used; ③The screwdriver was not 18 in the same direction as the screw, resulting in wear at the tail of the screw; ④The 19 soft tissue or hyperplastic bone in the groove was not cleaned when the nail was 20 removed (13,14); ⑤When the combination of the screw and the plate is over 21 tightened, the surgeon tried to use a power tool to remove the screw instead of the 22 T-handle screwdriver (15). 1 In recent years, with the increasing preference of clinicians for locking plate and 2 screw system, the incidence of slide wire screw has increased significantly, which has 3 also attracted the attention of orthopedic surgeons. Through continuous research, 4 improvement and practice, many scholars have put forward a variety of methods to 5 remove slide wire screws. We classify the existing mainstream methods into the 6 following categories: 1. Cutting off the tail and taking screw. After destroying the 7 tail of the screw with a tungsten steel drill, the plate is removed first, and then the 8 screw is removed by expanding the screw path with a ring drill or Kirschner needle. 9 Gupta improved this method by directly grinding the plate along the screw direction 10 with a grinding drill, and then removing the plate and screws. This method can 11 remove multiple screws without being restricted by the position of the screws. But it 12 takes a lot of time, and a large amount of metal debris will be produced in the process, 13 which is often stranded in the patient's body (10). And the method will damage the 14 normal bone and reduce the bone strength, which is not conducive to early Groove-changing method. Make a new "one-shaped" groove at the tail of the slide 4 wire screw and remove the screw with a corresponding screwdriver. This method will 5 produce a large amount of metal debris in the process, and the new groove is 6 generally shallow and irregular, so that the friction force produced by the screwdriver 7 is low. The above methods all have some limitations and shortcomings. By 8 summarizing up the experiences and reviewing the relevant literature, we put forward 9 the nail groove reconstruction method on the basis of the Groove-changing method. 10 Through the control study, it is found that it has a good effect. 11 From the results, we can see that all slide wire screws can be removed in both of the screw. It is best to use the T-handle screwdriver to get as much friction as possible. 1 Although we have made sufficient preoperative preparations and standard operation, 2 it is inevitable that the screw will slide wire. When it is confirmed that the screw 3 cannot be removed, you should communicate with the patient and his family and give 4 up removing the screw in order to avoid serious complications. 5 5. Conclusion: 6 This control study shows that the nail groove reconstruction method can be used to 7 remove the slide wire screw that is on the locking plate, especially for hexagonal 8 screws with 3.5mm diameter. Furthermore, compared with the traditional methods, 9 the nail groove reconstruction method has the advantages of small trauma, simple 10 operation, quick recovery, safe and effective. The data and materials might be obtained from the corresponding author upon 9 request.

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Competing interests: 11 The authors declare that they have no competing interests.