Treatment of Patellar Fracture With Kirschner Wire Tension Band With Absorbable Sutures

shilong Jin Zhijin Hospital of TCM Fengwei Qin (  gzyqfw@126.com ) Guangzhou Hospital of Integrated Traditional and Western Medicine https://orcid.org/0000-00025085-2725 qiyuan Chen Zhijin Hospital of TCM jinfang Hu Zhijin Hospital of TCM libin Wei Zhijin Hospital of TCM yuanheng Zhou Zhijin Hospital of TCM jian Liu Zhijin Hospital of TCM xinlong Zhu Zhijin Hospital of TCM cheng Gao Zhijin Hospital of TCM


Introduction
Patellar fracture is relatively common, the incidence of 0.5% -1.5% [1], The surgical treatment of patella fractures mainly includes traditional and modi ed tension bands, hollow screw titanium cables, plate xation and other surgical methods [2] Among these methods, the Kirschner wire tension band xation method is simple and reliable, and it is still the most commonly used method for the treatment of patella fractures [3][4][5] . However, the Kirschner wire tension band technique also has many complications, such as the loosening of the Kirschner wire, the interference of the wire on the soft tissue, and the displacement of the fracture end, especially the comminuted patella fracture or the osteoporotic patella fracture. The above risks are higher. And it is prone to serious consequences such as failure of internal xation and nonunion of fractures [6][7][8]. In view of the limitations of traditional tension band technology, we use Kirschner wire combined with absorbable suture tension band technology to treat patella fractures. This surgical method is simple to operate and reliable, especially suitable for comminuted patella fractures.
This study aims to evaluate the clinical effect of Kirschner wire combined with absorbable suture tension band technology in the treatment of patella fractures.

Data And Methods
This was a retrospective observational cohort study, and the present study was approved by the institutional review board. The medical records and radiographs of patients who presented with patella fracture from January 2018 to December 2019 in our institution was reviewed. The inclusion criteria were as follows: patella fracture, surgical treatment with Kirschner wire combined with absorbable suture tension band technology, and patient age 18 years. The exclusion criteria were patients with less than 11 months of follow-up and periprosthetic fracture. Out of the initial 78 patella fractures that were screened during the period, 32 patients (17 male and 15 female) were included in this study with an average age of 58.6 (range, 19-84) years. The average follow up was 13.0 (range, 11-24) months. The X-ray or CT imaging results of all patients before and after the operation were collected, and the preoperative X-ray or CT results were classi ed according to the AO/OTA standard. Collect and record all postoperative clinical data and complications. Numerical Rating Scale (NRS) score, Levack score system, WOMAC test form of pain, stiffness and function, and knee joint range of motion (ROM) were applied for functional evaluation.
Surgical technique (Fig. 1, 2) The patient was placed in the supine position, continued epidural anesthesia, a thigh tourniquet was applied and in ated to 350mmHg, and the anterior median longitudinal incision approach of patella was selected. The periosteum and aponeurosis of the innermost layer were not cut along the incision, and the tissue was removed to both sides to expose the extension of the supporting zone. If the expansion part is broken, the patella fracture site can be explored from the fracture site. If the expansion part is complete, the longitudinal small incision can be made for exposure exploration according to the fracture site needed to be explored. First, the patellar fracture was reduced under direct vision, and the patellar fracture was temporarily xed and stabilized with the point reduction forceps. For the fractures that could not be temporarily xed and stabilized, the prepatellar fascia could be repaired with the No. 1 absorbable line (PGA, 2000127, shanghai, China) (Fig. 2, c-A). After fracture reduction was con rmed by C-arm uoroscopy machine (Siemens, Germany), Kirschner wire (φ2mm) was used to x the fracture block perpendicular to the fracture line as far as possible according to the position of the bone block, and the Kirschner wire passed through the contralateral cortical surface of the bone (Fig. 2, d). It is easier to bend the upper end of Kirschner wire by using stainless steel suction tube or hollow sleeve with diameter of 3 -4mm (Fig. 2, e-B). Then pull the Kirschner wire down to make as much contact as possible with the bone surface. Then bend the lower end of the Kirschner wire in the same way. The position and length of the Kirschner wire were determined by C-arm uoroscopy machine, and the effect of fracture reduction and xation was con rmed (Fig. 2, h). The excess Kirschner wires were cut off, the tail was reserved for about 5mm, and rotated inward 45° to avoid the stimulation of soft tissue by the stump of the Kirschner wires Postoperative management There was no use of hinged knee brace or other external xation. The isometric contraction exercise of quadriceps femoris muscle was allowed one-day post-operation ( Fig. 3, a). The second day after surgery (Fig. 3, b), the knee joint exion and extension exercises were performed with the assistance of continuous passive motion (CPM). On the third day after the operation, the patients were encouraged to get out of bed and walk on crutches (Fig. 3, c). Two weeks after the operation, the active function exercise of the knee joint was strengthened (Fig. 3, d). About 4 weeks postoperatively, vigorous active exion and extension movements can be performed without the aid of instruments (Fig. 3, e).

Results
A total of 32 patients with patellar fracture were screened and included in the study. All cases were closed fracture and were treated by Kirschner wire combined with absorbable suture technology. The baseline characteristics of all patients were shown in Table 1.
The clinical outcomes were shown in Table 2. All patients had fracture unioned. There was no wound infection, Kirschner Wire exposure and second displacement of fracture fragmen. Kirschner wire loosening happened in two case at six months post-operation. None of the patients had knee stiffness, and the range of motion of the knee was 125.6° (110 -135). The average NRS score for knee pain was 7.5 (6-9) preinjury and 0.5 (0-2) at the last follow-up. Knee joint function recovered well, excellent and good rate was 93.75% (30/32). The average Levack score was 10.0 (6-12), which included twenty evaluations of "excellent" and twelve of "good". WOMAC averaged 22.5 (14 -38).
Techniques of internal xation using stainless steel wire, such as the modi ed tension band method, are widely used. However, symptoms and complications related to the stainless steel wire are not uncommon after this technique [5]. The incidence of complications related to wire loops was 47%; furthermore, 1/4 had associated symptoms and required wire removal [9].
In recent years, the treatment of patella fractures with non-metallic internal xation materials has attracted more and more attention from clinical researchers. Current studies have shown that nonmetallic materials are used to treat olecranon fractures, proximal humeral fractures, and Achilles tendon ruptures, and have achieved good therapeutic effects [14][15][16][17]. Researchers have found that non-metallic materials have a signi cantly reduced repulsion response to the human body, and have less irritation to surrounding soft tissues. More importantly, studies have con rmed that there is no signi cant difference in mechanical properties between non-metallic materials and metal internal xation materials [10]. For patella fractures, studies have also shown that non-metallic internal xation materials can also achieve good therapeutic effects, but there are many  with fewer postoperative complications. Third, the technology is rmly xed and can achieve rapid recovery to the greatest extent. In this study, all patients did not need to place drainage tubes after surgery, and immediately performed knee exion and extension exercises with continuous passive motion (CPM) and assistance on the rst day after surgery. The patients were guided to walk on the ground within 1 week after surgery without the assistance of crutches or braces, and basically returned to normal walking 4 weeks after surgery. Fourthly, there were few postoperative complications with this technique.
Only 2 patients (2/32) had Kirschner wire loosening within 6 months after surgery, but the fracture was completely healed and the Kirschner wire was removed in advance.
In this study, absorbable sutures were used instead of traditional steel wires, which signi cantly reduced the complications caused by irritation and fracture of steel wires. Studies have con rmed that the strength of absorbable sutures can replace steel wire and Kirschner wire to form a tension band system [10]. In this study, we also improved the suture method of absorbable sutures. The absorbable suture is further strengthened by an arc suture along both sides of the patella using a hemlock suture, and the suture is repeated twice. During the operation, attention should be paid to the selection of the starting and If intraoperative rupture or tear of prepatellar fascia is found, absorbable sutures can also be used for repair. It is recommended to repair before the implantation of the Kirschner wire, because this can make the position of the crushed fracture block relatively stable and facilitate the implantation of the Kirschner wire.
In this technique, ordinary Kirschner wires are still used. The diameter of the Kirschner wires is selected according to the patient's physical condition. Generally, the diameter of the Kirschner wires is 2.0 or 2.5mm. During the operation, the patella can be temporarily xed with point-like reduction forceps, and then the prepatellar fascia can be repaired. Finally, two parallel Kirschner wires can be inserted longitudinally perpendicular to the fracture line. If there are more fractures, a third Kirschner wire can also be inserted horizontally perpendicular to the direction of fracture line. Both ends of the Kirschner wire are bent and cut off about 5mm from the tail end. The hollow stainless sleeve (such as suction tube or hollow screw driver) with a diameter of 3 4mm is recommended to bend the Kirschner wire so that it is bent as close to the bone surface as possible.
Of course, there are also shortcomings in this study, such as a small sample size, no comparative study with other internal xation techniques for patella fractures, and whether different speci cations of absorbable sutures have an impact on the xation effect. In addition, this technology still needs to be further proved in theoretical research. These are also the directions we will focus on in the next step.

Conclusions
In general, the Kirschner wire tension band with absorbable sutures can effectively x various types of patellar fractures, and can avoid the common loosening of internal xation and pain caused by internal Tables Tables 1 and 2 are not available with this version.   Postoperative rehabilitation. a. Knee exion and extension exercises in bed. b. The knee joint exercises was performed with the assistance of CPM. c. The patient got out of bed and walked. d. Two weeks after surgery, the suture was removed and the knee joint was strengthened. e. The knee exion and extension function of the patient returned to normal 4 weeks after operation.