Since the Nice knot was proposed, it has been widely studied and applied; Ian Peeters[11] suggested that a non-metallic cerclage technique mainly in the upper limb might become the golden standard, while in the lower limb both metallic and non-metallic cerclage techniques were complementary and dependent on indication. The biomechanical[12] comparison showed that high-performance sutures provided an alternative to steel wire for cerclage fixation, which had certain clinical application value. A recent biomechanical study[13] demonstrated that the Nice knot, especially using fiber wire, was biomechanically superior to the surgeon's and Tennessee slider knots. P Collin[10] et al. made a mechanical analysis of Nice knot, which provided an option for sliding and locking knots, which reduced the risk of elongation during dynamic stress. Two half hitches were recommended to ensure adequate knot security. In 2016, Pascal Boileau[7] described a novel suture fixation technique that combined a doubled suture with a sliding knot and had replaced metallic wires and cables for bone fixation. The doubled-suture Nice knot has been used for the treatment of proximal humeral fractures, rotator cuff injuries, and the small- or medium-sized wounds [9]. Especially recently, Mengcun Chen[8] systematically explained the effect of Nice Knots as an auxiliary reduction technique in displaced comminuted patella fractures. As far as we know, there are very few studies about the application of the Nice knots in the treatment of the displaced clavicle fractures.
Although the treatment of clavicle fractures without displacement or complex displacement remains controversial, in young patients with > 15 mm clavicle shortening in the frontal plane, and especially in case of comminution and displacement fracture, surgery should be considered, due to elevated risk of non-union [6]. In recent years, the treatment of clavicle fracture had made progress, especially in the surgical treatment of middle clavicle fracture. Many studies [3, 14, 15] suggested surgical treatment of comminuted displaced mid- clavicle fractures to reduce shoulder discomfort caused by nonunion and malunion. The technique needed to take account of clavicle anatomy: especially periosteal vascularization in midshaft fracture. This segmentation of vascularization was difficult to objectify in surgery and suggested that intraoperative midshaft periosteum loss should be minimized [6, 16]. For the surgical treatment of closed middle clavicle fracture, in order to reduce soft tissue trauma, people continue to study the surgical methods. Current surgical options included superior plating, anterior-inferior plating, dual plating, and intramedullary nail fixation. Since the clavicle fracture was fixed with Kirschner wire in 1950, the technique of locking intramedullary nail had been developing continuously, indirect reduction could be used to fix the fracture end with intramedullary nail, so as to reduce the damage of soft tissue and blood supply at the fracture end, which could achieve satisfactory clinical effect[17]. Some clinical studies [18, 19] had shown that major re-intervention and re-fracture after implant removal occurred more frequently after plate fixation of comminuted displaced midshaft clavicle fractures. There were no significant differences between plate fixation and intramedullary fixation in terms of function and nonunion. However, for comminuted unstable fractures, plate treatment had a greater advantage. In recent literature,[3] the operative treatment of clavicle fractures showed lower rates of long-term sequelae, specifically lowering the incidence of symptomatic malunion and nonunion and improving functional outcomes. Some literatures [6] believe that plate osteosynthesis is the gold standard treatment for displaced midshaft fractures (DMCF). In the segmental defect model of clavicle fracture[20] , the locking plate increases the torsional stiffness compared with the standard plate. This study described a simple, practical, and effective method to assist in the incisional repositioning of mid-clavicle comminuted displaced fractures based on the principles of reducing periosteal dissection and blood transport disruption and achieving anatomical repositioning as much as possible. In this study, the clinical results and functional outcomes of the displaced clavicle fractures with ORIF were good in both groups at the last follow-up.
The advantage of Nice knot is that it does not destroy the blood flow around the fracture like steel wire, and it can give satisfactory reduction to the subclavian fracture fragments. As we predicted, the Nice knot assisted reduction group could achieve better anatomical reduction without excessively peeling off the periosteum, and track the operation time, intraoperative blood loss, and intraoperative fluoroscopy time. We found that the operation time and intraoperative fluoroscopy time in NK group were significantly shorter than those in TK group (P<0.01), and not only that, we also found that the intraoperative blood loss in NK group was also significantly less than that in TK group (P<0.01). Therefore, Nice knots is promising method for the fixation of displaced fracture of clavicle fracture.
As we predicted, in the comparison between the two groups, the Nice knot assisted reduction group can achieve better anatomical reduction without excessive stripping of the periosteum, while reducing intraoperative blood loss and shortening the operation time. The Nice knots were used to stabilize the end of the fracture according to the type of fracture. For simple displaced fracture, the instrument was used to stabilize the fracture end and then bind 1-2 Nice knots around the fracture end. Nice knot had its special significance for comminuted and displaced fractures. Martijn hulsmans [21]reviewed the biomechanical studies of clavicle fractures, then pointed out that the loss of cortical line in wedge-shaped fracture and comminuted fractures directly affected the stability of intramedullary and plate fixation. On the other hand, the smaller fracture block screws were not suitable, the broken end nails were more likely to be loosened, and there was a greater risk of destroying the blood supply and affecting the healing of steel wire binding. The Saeed Asadollahi[22] study points out that some complications can be avoided by improving surgical techniques and careful use of cannulated screws for adequate fixation to obtain sufficient medial fragments. However, broken lines or butterfly-shaped bone blocks without treatment could result in bone defects and affect fracture healing. Blindly pursuing anatomical reduction and reduction was convenient. Excessive stripping of soft tissue around the fracture fragments would lead to the cutting off of blood supply of bone block, resulting in ischemic necrosis, delayed healing, nonunion and plate fracture. Recently, in order to reduce the damage of blood supply around the fracture, some studies[23, 24] have even shown that MIPPO technology can achieve good clinical effect by inserting clavicular plate, but it also loses the advantage of reducing complex fracture ends. The Kirschner wire or reduction forceps was firstly used to temporarily fix the main part of the fracture, and then bind it with Nice knots; finally, the remaining bone block should be kept as far as possible to keep its surrounding blood supply on the defect trunk. During our follow-up, we found two cases of plate fractures. Although there is no evidence to show the specific cause of clavicular plate fracture, we speculate that clavicular plate fracture may be related to coracoclavicular ligament traction. Anatomically, the injury of coracoclavicular ligament or acromioclavicular ligament can lead to shoulder instability. However, the stress at the broken end of the clavicle fracture is more concentrated because of the traction of these soft tissues in the middle clavicle fracture. Therefore, we added a Nice knot after placing the steel plate to stabilize the shear force between the fracture end and the steel plate. Of course, the corresponding evidence requires further biomechanical analysis.
Unlike the repair of proximal humerus, patella and rotator cuff injuries, clavicle fractures are mostly sutured and reduced under indirect vision. Therefore, we need to wind the clavicle during the operation, although we have not found any cases of subclavian vascular and nerve injury in our study, and many studies have pointed out that there are few intraoperative complications in the surgical treatment of clavicular fracture[22, 25]. However, during the operation, we still have to be very careful and pay attention to the course of the subclavian vessels and nerves in order to avoid damage during winding and drilling. In addition, the number of Nice knot used in clavicle fractures should be used reasonably to prevent excessive nodules from affecting the blood supply of the periosteum.
Although our data show that there are differences in operation time, intraoperative fluoroscopy time, intraoperative blood loss and fracture reduction satisfaction between the two groups, there are still some shortcomings in this study: 1. this study was a single-center retrospective clinical case analysis with a low level of evidence and a small number of cases, so multicenter, large sample case analysis will be needed to confirm the results of this study. It also illustrated the practicability and feasibility of Nice knot as a useful reduction tool in the treatment of displaced clavicle fracture. 2.This study was not randomly grouped, there was a certain selection bias. 3. Although the clinical and imaging effects of Nice knot were better than those of conventional reduction group, it was not clear whether this difference had clinical significance. And whether there are long-term complications, more long-term follow-up results are needed.