Anchor loop plate fixation for the treatment of sleeve avulsion fracture of the inferior pole of the patella : finite element analysis and case series

Anchor loop plate fixation for the treatment of sleeve avulsion fracture of the inferior pole of the patella : finite element analysis and case series | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Anchor loop plate fixation for the treatment of sleeve avulsion fracture of the inferior pole of the patella : finite element analysis and case series Taotao Ren, Bing Du, Bo Wu, Shuai Ji, Yao Lu, Zhong Li, Ming Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8831920/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Objective The purpose of this study was to compare the biomechanical stability of the Kirschner wire tension band combined with patellar cerclage and anchor loop plate ( ALP ) in the treatment of inferior patellar fracture with different fracture lines and to provide a new solution for the treatment of sleeve avulsion fracture of the inferior pole of the patella. Methods The finite element model was established, and the lower pole fractures of different fracture block sizes were graded according to the distribution of the lower pole fracture line. The model was subjected to finite element mechanical test under 500 N pressure to test the biomechanical properties of Kirschner wire tension band combined with patellar cerclage anchor nail loop plate fixation for the treatment of patellar lower pole fractures with different fracture lines. The clinical data of 8 patients with sleeve avulsion fracture of the inferior pole of the patella admitted to our hospital from June 2018 to June 2022 were retrospectively analyzed. All patients were treated with a newly designed anchor loop plate. The safety and effectiveness of this new technique in the treatment of sleeve avulsion fracture of the inferior pole of the patella were analyzed. The safety activity of passive flexion and extension of the knee joint during the operation was observed by consulting the medical records and follow-up results. The fracture healing, knee function recovery and postoperative complications were observed. Bostman score was used to evaluate knee joint function 3 and 9 months after operation. Results The biomechanical analysis of the finite element model showed that the maximum displacement of the Kirschner wire group was 1.77 times that of the ALP group at I-degree of the lower pole bone, the maximum stress of the Kirschner wire group was 1.21 times that of the ALP group, and the maximum stress of the Kirschner wire group was 13.29 times that of the ALP group. The maximum displacement of the II-degree of the lower pole bone in the Kirschner wire group was 2.22 times that of the ALP group, the maximum stress in the Kirschner wire group was 1.53 times that of the ALP group, and the maximum stress in the Kirschner wire group was 15.34 times that of the ALP group. The maximum displacement of the III-degree of the lower pole bone in the Kirschner wire group was 3.43 times that of the ALP group, the maximum stress in the Kirschner wire group was 1.60 times that of the ALP group, and the maximum stress in the Kirschner wire group was 16.86 times that of the ALP group. All avulsion fractures of the inferior patellar pole healed well without serious complications such as internal fixation failure or infection. The average operation time was 81.87 min ( 72–87 min ), the average final knee range of motion ( ROM ) was 124.50 ° ( 118 ° -130 ° ), the average Bostman score was 26.38 ( 24–29 ) in the third month, and the average Bostman score was 28.63 ( 27–30 ) in the ninth month. All patients showed good knee function one year after the operation. Conclusions With the change of fracture line to the distal end, the biomechanical stability of anchor loop plate was less affected by the change of fracture line, while the influence of Kirschner wire tension band combined with patellar cerclage technology tended to be unstable. Therefore, for sleeve avulsion fracture of the inferior pole of the patella, anchor loop plate has more biomechanical stability. In clinical practice, sleeve avulsion fracture of the inferior pole of the patella can be firmly fixed, and early functional exercise of knee joint can be allowed to bring good knee joint function to patients with sleeve avulsion fracture of the inferior pole of the patella. Health sciences/Anatomy Health sciences/Diseases Health sciences/Medical research Patellar fractures Plates Sleeve avulsion fracture Tension band Finite Element Analysis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Background Sleeve avulsion fracture of the inferior patellar pole is a serious injury involving the inferior patellar pole and the starting point of the patellar ligament. It is a special type of fracture of the knee extension device [ 1 ] .The injury mechanism is complex and often involves the destruction of the bone-cartilage-ligament complex, which is relatively common in children and adolescents, especially in pre-adolescent men who participate in high-intensity exercise [ 2 ] .Since the inferior pole of the patella is the hub of the quadriceps contraction force transmitted to the tibial tubercle through the patellar ligament, such fractures directly destroy the continuity of the mechanical conduction of the lower limbs. Improper treatment can easily lead to serious complications such as knee extension dysfunction, patella low, and traumatic arthritis [ 3 , 4 ] . The overall treatment strategy of avulsion fracture of the inferior pole of the patella mostly depends on surgical fixation. However, due to the variable fracture line and poor bone conditions, the selection of surgical options and the optimization of fixation methods are still controversial. The existing research mainly focuses on the clinical application and efficacy evaluation of traditional fixation methods, such as Kirschner wire tension band fixation and plate fixation. Their respective advantages and disadvantages and application scope have been preliminarily clarified [ 5 , 6 ] . However, there is still a lack of systematic analysis of the biomechanical properties of different fracture lines in the inferior pole of the patella, especially the mechanical stability and clinical safety of the new fixation technology. In addition, the existing literature is mostly case reports or small sample reviews, and there is a lack of comprehensive research combining finite element analysis and clinical large sample data, which limits the clinical promotion and application of related technologies. In view of the above shortcomings, this study innovatively combines finite element analysis with clinical case treatment reports to construct avulsion fracture models of the inferior patellar pole under different fracture line distributions, and quantitatively evaluates the biomechanical properties of the new anchor loop plate fixation technique. The finite element method simulates the changes of the force of the avulsion fracture of the inferior pole of the patella under different fracture lines, and compares it with the traditional fixation method, which provides a mechanical stability reference for the optimization of the surgical fixation method. At the same time, combined with the clinical case series, this study systematically reviewed the application effect and safety of the anchor loop plate in the actual operation. Combining biomechanical research with clinical research, the division of different fracture lines reflects the trend from simple inferior patellar fracture to sleeve avulsion fracture fixation, which provides a new idea for the treatment of sleeve avulsion fracture of inferior patellar pole. Materials and Methods Finite element analysis: collection of imaging data A 35-year-old male patient with a patellar fracture ( voluntary informed consent ) weighing 70 kg was selected. X-ray examination showed that there was no lesion in the contralateral patella, and the bone was good. A Spiral CT scan was performed. The scanning target was the healthy patella of the patient. The scanning length was from 5 cm above the upper pole of the patella to 5 cm below the lower pole of the patella. The scanning conditions were 120 k V, 155 m A, and the scanning layer thickness was 1 mm. The scanning information was collected and processed, and the continuous image data was saved in DICOM format. This study was approved by the Ethics Committee of Xi 'an Red Cross Hospital, and all the research methods in this study are implemented in accordance with the relevant guidelines and regulations. Finite element model of patella construction The data were imported into Mimics15.0 software, and the rough model of the femur was established by the commands of threshold segmentation and region growth in the software. Import it into Geomagic 2017 software. The model is subdivided into triangular patches, noise reduction and smoothing. Three-dimensional models of patellar cancellous bone and cortical bone were constructed by precise surface treatment. The above model was imported into Solidworks software, and the patella was divided into 16 equal parts from the upper pole to the lower pole. In the lower pole area of the patella, three fracture lines were constructed to divide the lower pole area of the patella into four equal parts. The 3 / 16 fracture line was defined as I-degree fracture of the lower pole of the patella, 2 / 16 fracture line was defined as II-degree fracture of the lower pole of the patella, and 1 / 16 fracture line was defined as III-degree fracture of the lower pole of the patella, as shown in Fig. 1 . The schematic diagram of different fracture lines of the inferior pole of the patella is shown in Fig. 1 .The experiment was divided into two groups: A.Kirschner wire group: Two Kirschner wires parallel to the articular surface of the patella were inserted into the patella, bound with steel wire ' 8 ', and the surface of the patella was bound with steel wire. B. Anchor loop plate ( ALP ) group: After the microplate was bent, it was attached to the surface of the patella through the patellar ligament and fixed with three screws and one steel wire. Volume mesh generation Finite element models were constructed using linear tetrahedrons(Fig. 2 ). This study showed 463524 elements with 628437 nodes in the tension band model after meshing and 258748 elements with 346795 nodes in the microplate model. The specific values are shown in Table 1 . Table 1 Number of nodes and elements in finite element model Number of nodes and elements in finite element model Finite element model Nodes Elements A group (K-wire) 628437 463524 B group(ALP) 346795 258748 Assignment of material properties The relevant material properties of the finite element model of patellar fracture were set up, and a three-dimensional finite element model similar to the actual model in terms of material parameters and mechanical behavior was established. The ligament is set to be a linear elastic material that only bears tensile stress. According to the actual data of clinical internal fixation device, the internal fixation structure involved in this study was constructed by Solidworks software, and the material properties of patellar cortical bone, patellar cancellous bone, Kirschner wire, steel wire and titanium alloy ( plate and screw ) were set [ 7 – 9 ] . The specific parameters are shown in Table 2 , and then the three-dimensional model and internal fixation model of the lower patella fracture with different fracture lines are assembled in SolidWorks software. Table 2 Model material parameters Name of the material Elastic modulus(MPa) Poisson ratio Cortical bone 10000 0.30 Cancellous bone 840 0.29 Steel wire 100000 0.29 Kirschner wire 200000 0.30 Titanium alloy 110000 0.30 Constraint and loading Two groups of three-dimensional finite element models with different fracture lines were fixed in the inferior patellar fracture models. A force of 0-500 N was applied to the inferior surface of the patella within 1 s [ 10 ] . Clinical data From June 2018 to June 2022, a total of 57 patients with patellar inferior pole fracture were treated, of which eight patients with patellar inferior pole avulsion fracture met the inclusion and exclusion criteria and received anchor loop plate surgery. There were five males and three females. The ages ranged from 45 to 76 years, with an average age of 58.38 years. Six cases were caused by falls, and two cases were caused by traffic accidents. The hospital ethics committee has approved this experiment, and all patients have signed the informed consent. Inclusion criteria: 1. CT diagnosis of sleeve avulsion fracture of the inferior pole of the patella; 2.Fixed with the anchor loop plate ; 3. New fractures were completed within one week after injury; 4. Knee joint function was good before injury; 5. Patients informed consent and complete clinical data. Exclusion criteria are as follows: 1. Patients with other types of patellar fractures; 2.Patients with distal femoral fractures or proximal tibial fractures ; 3. Combined with patellar fracture or patellar ligament injury; 4. patients treated with other fixation methods; 5. Lost follow-up or follow-up less than nine months. Surgical procedure After the patient's anesthesia was satisfied, the supine position was taken, routine disinfection was performed, a sterile surgical scarf was spread, and the tourniquet was placed close to the thigh. During the operation, the sleeve avulsion fracture of the inferior pole of the patella block was exposed by the median anterior approach, the joint cavity was rinsed, and the blood clots around the joint and at the fracture end were removed. A small incision was made at the junction of the patellar ligament, and the lower pole with a sharp knife, and the long arm of the plate passed through the patellar ligament from the inside to the outside. Then, the short arm of the plate was dragged to the lower pole of the patella, and the plate was adjusted with the help of the fluoroscopy machine to attach to the surface of the patella. After satisfactory forming, the steel wire is penetrated. Once again, the long arm of the steel plate passes through the small incision of the patellar ligament from the inside to the outside, dragging the lower pole bone block to reset. When the local bone block is squeezed, the lower bone piece can be sutured with a suture line, and the whole is sutured to the short arm hole of the anchor plate. Lumbar puncture needle assisted wire puncture, through the inner and outer support band and soft tissue, wire ring tightened. ( wire diameter is 1 mm ). Then the plate was fixed with 2.7 screws. Knee flexion was performed during the operation to check fracture stability. Rinse the wound repeatedly with plenty of normal saline. Suture the patellar ligament incision, align the flap suture, and suture the skin layer by layer. The knee joint passive flexion and extension activities were observed and recorded immediately. The key steps in the operation are shown in Fig. 3. Figure 3. Intraoperative situation of anchor loop plate in the treatment of sleeve avulsion fracture of the inferior pole of the patella. A. Incision exposure fracture line. B. Cut a small incision at the patellar ligament with a scalpel. C. One end of the long arm of the pre-bending plate passes through the patellar ligament hole. D and E. The plastic bone plate was inserted into the steel wire, and the lumbar puncture needle was assisted after fracture reduction. F. Screw implantation. G. Immediate joint passive flexion and extension activities. H and I. Intraoperative fluoroscopy. Outcome measures On the second day after the operation, the dressing was opened to observe the wound, the wound was disinfected strictly, and the dressing was replaced. The X-ray and CT films of the knee joint were retrospectively analyzed. Actively carry out the flexion and extension of the knee joint, and the movement angle gradually increases ( the target angle of movement is 90 ° 1 week after surgery ). Half-weight-bearing training was started one day after the operation, and full-weight-bearing training was carried out one month after the operation. X-ray films of affected limbs were reviewed every four weeks after the operation to evaluate fracture healing, guide patients to carry out knee joint functional exercises, record knee joint activity, and record surgical complications. Fracture healing was based on X-ray examination results and clinical results. X-ray examination showed that the fracture healed. The clinical results showed that the patient could walk normally without knee pain, and the fracture was healed. The knee joint function score was evaluated by the Bostman score [ 11 ] . Results Finite element analysis: displacement of fractures On the second day after the operation, the dressing was opened to observe the wound, the wound was disinfected strictly, and the dressing was replaced. The X-ray and CT films of the knee joint were retrospectively analyzed. Actively carrying out the flexion and extension of the finite element analysis under 500 N load of different fracture lines is as follows. The biomechanical test results of the finite element model showed that the maximum displacement of the K-wire group and the ALP group at the I-degree of the lower pole bone was 0.122 mm and 0.069 mm, respectively. The maximum displacement of the K-wire group was 1.77 times that of the ALP group. The maximum displacement of the K-wire group and the ALP group at the Ⅱ-degree of the lower pole bone was 0.173 mm and 0.078 mm, respectively. The maximum displacement of the K-wire group was 2.22 times that of the ALP group. The maximum displacement of the K-wire group and the ALP group at the Ⅲ-degree of the lower pole bone was 0.288 mm and 0.084 mm, respectively. The maximum displacement of the K-wire group was 3.43 times that of the ALP group, as shown in Fignnnnnnure 4. With the movement of the fracture line to the lower pole of the patella, the advantage of the ALP group in maintaining stable reduction was more significant. Finite element analysis results. Finite element analysis: Internal fixation and stress distribution of inferior patella pole The maximum internal fixation stress of the K-wire group and the ALP group showed that the I-degree of the lower pole bone was 587.35 MPa and 485.67 MPa, respectively, and the maximum stress of the Kirschner wire group was 1.21 times that of the ALP group. The maximum stress at the Ⅱ-degree of the lower pole bone was 73.26 MPa and 511.65 MPa, respectively. The maximum stress in the Kirschner wire group was 1.53 times that in the ALP group. The maximum stress at the Ⅲ-degree of the lower pole bone was 856.80 MPa and 536.94 MPa, respectively. The maximum stress of the Kirschner wire group was 1.60 times that of the ALP group. The maximum stress of the polar bone in the K-wire group and the ALP group showed that the I-degree of the lower pole bone was 77.26 MPa and 5.81 MPa, respectively. The maximum stress of the polar bone in the K-wire group was 13.30 times that of the ALP group in the Ⅰ-degree of the lower pole bone. The maximum stress of the polar bone in the K-wire group was 15.34 times that of the ALP group in the Ⅱ-degree of the lower pole bone. The maximum stress of polar bone in the K-wire group was 16.86 times that of the ALP group in the Ⅲ-degree of the lower pole bone. The stress concentration is distributed at each contact point between the internal fixation and the polar bone. The overall stress situation of the ALP group is stable at a lower level. As the fracture line moves to the lower pole of the patella, the smaller the peak value of the stress distribution in the ALP group, the more significant the advantage. The two sets of finite element analysis cloud images are shown in Fig. 5 and Fig. 6. The peak displacement and peak stress of the two internal fixation schemes. Comparing the peak displacement and peak stress values of the K-wire group and the ALP group, the overall peak displacement and peak stress of the ALP group were at a lower level than those of the K-wire group. In particular, the stress of the patella lower pole bone block in the ALP group was significantly lower than that in the K-wire group. As the fracture line moves to the distal end of the patella, the ALP changes less, while the K-wire group is affected by the fracture line. The change of the distal movement is greater, which indicates that the ALP group has a more stable biomechanical structure, as shown in Fig. 7 and Fig. 8. Clinical outcome The 8 cases of sleeve avulsion fracture of the inferior pole of the patella included in the study were well-healed without serious complications such as internal fixation failure or infection. The average operation time was 81.87 min ( 72–87 min ), the average final knee range of motion ( ROM ) was 124.50 ° ( 118 ° -130 ° ), the average Bostman score was 26.38 ( 24–29 ) at the third month, and the average Bostman score was 28.63 ( 27–30 ) at the ninth month. All patients showed good knee function one year after the operation. The typical case is shown in Fig. 9 . Discussion 1.Special anatomical structure and treatment of patellar sleeve avulsion fracture The inferior pole of the patella is the starting point of the patellar ligament, and its anatomical structure is special. The trabecular bone structure in this area is unique and the blood supply is relatively weak, making it a stress concentration area in the knee extension device. This anatomical feature makes the lower pole of the patella prone to injury when subjected to strong traction. In particular, the transition zone between the patellar ligament and the lower pole of the patella is a mechanically weak point. When the knee joint is subjected to acute violence or chronic overload, this area is prone to avulsion fractures with cartilage or thin bone slices as the ' cap ', while the ligament substance itself may remain relatively intact [ 12 ] . The integrity of the knee extension device is essential for maintaining normal knee function. It not only ensures the normal mechanical trajectory of the patellofemoral joint, but also plays a decisive role in the extension of the knee joint within 30 ° [ 13 ] . The choice of surgical treatment strategy for sleeve avulsion fracture of the lower pole of the patella lies in the accurate evaluation of the nature of the injury, the state of the fracture block and the soft tissue conditions. For patients with old fracture nonunion or malunion, due to the presence of fibrous tissue or callus between the fracture ends, and often accompanied by knee extension device shortening and joint stiffness, simple internal fixation is often difficult to obtain stable healing and good function. At this time, the operation should be based on the integrity of the patellar ligament to determine whether reconstruction is needed after fully releasing the joint adhesion and restoring the normal position and height of the patella [ 14 ] .When considering surgical treatment, both the internal fixation of the inferior pole of the patella fracture and the reconstruction of the patellar ligament must be aimed at restoring the natural anatomy and biomechanics of the knee joint [ 15 , 16 ] . 2.New internal fixation technology strategy for sleeve avulsion fracture of the lower pole of the patella Tension band fixation is a classic method for the treatment of patellar fractures, especially non-comminuted fractures. Its core biomechanical principle is to convert the tension acting on the anterior surface of the patella in the flexion and extension of the knee joint into the pressure at the fracture end, thereby promoting fracture healing [ 17 ] . However, before the application of tension band technology, the quality of bone block must be carefully evaluated to ensure that it can withstand the cerclage force of steel wire and avoid the fixation failure caused by insufficient holding force [ 18 ] . The lower pole of the patella is avulsion fracture, usually the bone block is small, and the tension band fixation technique is difficult to provide sufficient holding force. For the innovation of tension band technology, some scholars have proposed the ' three needles and two cables ' structure for the treatment of avulsion fracture of the inferior pole of the patella. Compared with the traditional steel wire tension band, this technology shortens the operation time, reduces the incidence of complications, and obtains better knee joint mobility and functional score [ 19 ] . However, for comminuted fractures or sleeve avulsion fractures, it is often difficult to obtain strong internal fixation by conventional tension band and tension band-related modified techniques. Suture anchors and suture bridge fixation techniques have become one of the mainstream minimally invasive fixation methods for the treatment of sleeve avulsion fractures of the lower pole of the patella, especially in cases of small bone mass, crushing or osteoporosis. The core of this technique is to implant suture anchors into the proximal bone of the lower pole of the patella, and use high-strength sutures to weave or bridge avulsed bone-ligament complex [ 4 ] . In recent years, with the in-depth exploration of internal fixation for the treatment of avulsion fracture of the lower pole of the patella, it is difficult to grasp the bone fixation for the avulsion fracture of the lower pole of the patella. Scholars have explored a variety of surgical methods to solve this traumatic orthopedic problem. For example, multi-directional three-dimensional steel wire ring fixation technology has been proved to have the advantages of reliable fixation, allowing early functional exercise and fewer complications [ 20 ] . A new type of implant was designed based on the principle of biomechanics, such as the ' smile necklace ' plate, which has the advantages of both plate fixation and tension band fixation. It aims to provide better fixation for osteoporotic comminuted fractures and facilitate early rehabilitation [ 3 ] . In addition, a ' hammock plate ' technique using synthetic sutures and low-profile mini-plates to form a ' hammock ' -like structure to lift bone blocks as a whole has also been proposed for comminuted lower pole sleeve avulsion fractures, aiming to achieve firm bone healing [ 21 ] . 3.The expected effect, biomechanical and clinical results of surgical treatment of avulsion fracture of the inferior pole of the patella. Since the location of the avulsion fracture of the lower pole of the patella does not involve the patellofemoral joint surface and does not require anatomical reduction of the articular surface, the main goal of treatment is to restore the knee extension device. The results of finite element analysis showed that under the same 500 N tensile load, the ALP group of different fracture lines showed smaller maximum displacement and smaller internal fixation stress in the comparison of different fracture lines, that is, in the I-degree, II-degree and III-degree of patellar inferior pole fracture, showing better biomechanical stability than the Kirschner wire group.The two groups have a massive gap in the stress of the lower pole fracture. ALP fixation will bring a more minor stress to the lower pole bone, while K-wire fixation will bring a more significant and more concentrated stress to the lower pole bone. Through further analysis of the data, we found that as the fracture line is closer to the distal end of the lower pole, the biomechanical stability of the K-wire group becomes more unstable during this dynamic change.In contrast, the displacement and stress of the ALP group remain at a low level and are less affected by the change of the fracture line, as shown in Fig. 7 and Fig. 8. From the perspective of biomechanical stability, this shows that the smaller the lower pole fracture block after the lower pole fracture of the patella, the more prominent the advantages of the ALP group fixation method. The clinical results showed that the average Bostman score nine months after surgery reached 28.63, and the final knee range of motion ( ROM ) was 124.50 ° on average, indicating that the knee function of patients undergoing ALP fixation recovered well after surgery. 4. The biomechanical properties of ALP are better when the fracture of the inferior pole of the patella is fixed with different fracture lines. The results of statistical finite element mechanical analysis showed that as the fracture line of the lower pole of the patella moved down, the biomechanical trends of the two internal fixations were as shown in Fig. 7 and Fig. 8. During the transformation of the fracture type from I-degree fracture of the lower pole of the patella to III-degree fracture of the lower pole of the patella, ALP was more stable in the three aspects of overall displacement, internal fixation stress and lower pole bone stress, and ALP fixation with the fracture line moved down, the change range was small, while the Kirschner wire tension band group changed greatly. As the fracture line tends to be larger than the III-degree of inferior patellar fracture, it is suggested that this method is not suitable for the treatment of avulsion fracture of the inferior patellar pole. In the dynamic process of moving down the fracture line, we noticed that the 8-shaped structure of the Kirschner wire tension band group was shrinking, and the contact surface between the Kirschner wire and the lower pole of the bone block was also shrinking rapidly. Perhaps due to the smaller contact area, the local pressure was greater, which made the biomechanical structure tend to be unstable. With the dynamic process of the fracture line moving down, we noticed that the area of the short arm of the plate in the stress concentration area was almost unchanged, which brought about a more stable structure. The severity of the fracture of the inferior pole of the patella was less changed, and its biomechanical stability was very stable. The application of ALP in the treatment of sleeve avulsion fracture of the inferior pole of the patella provides a confirmation of biomechanical stability. conclusion In our previous study, it has been confirmed from the perspective of clinical and biomechanical that ALP uses the inferior pole of the patella and the patellar ligament as a whole towing technique, which can be used as a new method for the treatment of the inferior pole of the patella fracture, and has achieved excellent research results. In view of the excellent biomechanical advantages of ALP, in order to further expand its application, the research team applied it to the treatment of more extreme sleeve avulsion fracture of the lower pole of the patella. In this special, difficult and technically demanding fracture of the lower pole of the patella, and achieved good clinical prognosis.The sleeve avulsion fracture of the inferior pole of the patella is indeed a more difficult fracture of the inferior pole of the patella. Because the sleeve avulsion fracture is a relatively rare type of patellar fracture, the existing studies usually only have relevant cases to report this type of patellar fracture, such as the case report of Shimasaki and Tsubosaka on the sleeve avulsion fracture [ 1 , 22 ] . Due to the inability to use tension band technology to fix, they use sutures to fix the fracture of the lower pole of the patella. The fixation strength is low, and there is no internal fixation device suitable for this unique patellar fracture. Most scholars use the surgical method of patellar ligament reconstruction, but patellar ligament reconstruction often has complications such as patellar height change and patellofemoral arthritis.However, some scholars have found that compared with the patellar ligament repair with the removal of the inferior pole of the patella, the preservation of the inferior pole of the patella usually does not cause the abnormal position of the patella after the operation, and the connection strength between the bone and the bone is greater than that between the bone and the ligament [ 23 ] . It enables patients to carry out early functional exercise and obtain better knee joint function. On the basis of retaining the advantages of bone-bone fixation, the screw hole design of ALP can be used as a suture site. In the case of patellar ligament tear, the suture can be fixed on the ALP after the patellar ligament is repaired by the suture, and the continuity of the patellar ligament can be indirectly restored. In this study, the finite element model was used to confirm that for the sleeve-shaped avulsion fracture of the patella, due to the very small amount of bone in the lower pole, the more concentrated the stress of the internal fixation on the bone block, the higher the probability of internal fixation failure. As the fracture line is closer to the distal end of the fracture, the smaller the bone block in the lower pole of the patella, and the tension band combined with the patella cerclage technique is difficult to stabilize. This is confirmed in the finite element analysis part of this study. Further finite element mechanical analysis results show that as the fracture line is closer to the distal end of the fracture, the smaller the bone block at the lower pole of the patella is, and the tension band combined with the patellar cerclage technique is difficult to stabilize. Fixed, and ALP technology is not affected by the fracture line, when the fracture block is small, its biomechanical stability is still good. Therefore, we applied ALP technology to the treatment of clinical patellar lower pole sleeve avulsion fracture, and obtained better clinical treatment effect, which provided a new surgical fixation idea for the special type of patellar lower pole sleeve avulsion fracture.In addition, in most cases, the failure of internal fixation in patients with the lower pole of the patella usually indicates that the volume of the lower pole bone block that can be used for fixation during the second revision surgery will be further reduced. The reduction of bone mass will make the internal fixation device unable to be fixed and be treated with patellar ligament reconstruction. We found that compared with the improved tension band technique, the biomechanical stability of the ALP device did not fluctuate significantly with the further reduction of the remaining bone volume. Therefore, the ALP device has the advantage of potentially stable fixation for the failure of the internal fixation in the first operation. We applied this technique to the failure of the internal fixation device and tried to perform secondary surgical fixation to obtain a better surgical treatment effect. Shortcomings of current research ALP has better biomechanical stability than modified tension band in the treatment of patellar inferior pole fractures with different fracture lines, and better recovery of knee joint function after operation, which is more prominent in the fixation of patellar inferior pole avulsion fractures. Anchor loop plate is an effective surgical method for the treatment of patellar inferior pole fracture, which brings new possibilities for the fixation of patellar inferior pole sleeve avulsion fracture. The limitations of this study are mainly reflected in the insufficient sample size and the lack of long-term follow-up data. The limitation of sample size may lead to insufficient statistical significance of the results, which affects the general applicability of the research conclusions. In addition, the finite element analysis used in this study simplifies the connection structure. The influence of soft tissues such as ligaments and muscles around the knee joint on mechanical stability was ignored. These soft tissues may cause specific errors, and further mechanical experiments are needed to verify our research results. Declarations Announcement : All patients with identifiable human images in this article have informed consent and signed consent for this study.All participants, including patients and researchers who participated in the study, agreed to the release of this study. Funding: Supported by the Shaanxi Provincial Science and Technology Department(No. 2025JC-YBQN-1238) and (No. 2025SF-YBXM-089). Author Contribution T.T.Ren and M.Li are responsible for the conception and writing of the article. B.Wu and S.Ji are responsible for consulting the relevant literature. B.Du is responsible for finite element analysis experiments. Y.Lu and Z.Li were responsible for manuscript proofreading and clinical CT data collection. Data Availability The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request. References Shimasaki, K., Uesugi, M., Kobayashi, T., Tanaka, H. & Ichimura, H. 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Suture anchor repair for distal patellar tendon avulsion in tibial tubercle fractures: a technical description and report of two cases. Cureus 16 , e54696 (2024). Ling, M., Zhan, S., Jiang, D., Hu, H. & Zhang, C. Where should kirschner wires be placed when fixing patella fracture with modified tension-band wiring? A finite element analysis. J. Orthop. Surg. Res. 14 , 14 (2019). Meng, D., Ouyang, Y. & Hou, C. [a finite element analysis of petal-shaped poly-axial locking plate fixation in treatment of y-shaped patellar fracture]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi . 31 , 1456–1461 (2017). Kim, Y., Kwon, M., Ryu, J. Y. & Moon, S. W. Biomechanical analysis of the kirschner-wire depth of the modified tension band wiring technique in transverse patellar fractures: an experimental study using the finite-element method. Clin. Orthop. Surg. 13 , 315–319 (2021). He, S. et al. Modified technique of separate vertical wiring for the fixation of patellar inferior pole fracture. J. Orthop. Trauma. 32 , e145–e150 (2018). Böstman, O., Kiviluoto, O. & Nirhamo, J. Comminuted displaced fractures of the patella. Injury 13 , 196–202 (1981). Negrão, E., van den Eede, E., Kyriazopoulos, A. & Romijn, M. G. Sinding-larsen-johansson syndrome with minimally displaced patellar sleeve avulsion fracture: a case report with multimodality approach and literature review. Skeletal Radiol. 52 , 1403–1407 (2023). Felli, L. et al. Anatomy and biomechanics of the medial patellotibial ligament: a systematic review. Surgeon 19 , e168–e174 (2021). Elbaz, M. A., Batra, A., Mohamed, A., Alkhateeb, K. M. & Abdulgadir, M. Proximal patellar tendon injury with avulsed periosteal sleeve: a case report and long-term follow-up. Int. J. Surg. Case Rep. 127 , 110870 (2025). Hargreaves, M., Sisson, H., Harris, C., Momaya, A. M. & Casp, A. J. Combined medial patellofemoral ligament and medial quadriceps tendon-femoral ligament reconstruction with single knotless anchor. Arthrosc. Tech. 13 , 103102 (2024). Martin-Alguacil, J. L. et al. Double-bundle technique for the reconstruction of the proximal medial patellofemoral complex, using the first layer of the quadriceps tendon as a graft. Arthrosc. Tech. 14 , 103268 (2025). Tan, B. Y., Ng, J., Ng, W. X., Wei, Y. & Kwek, E. The evolution of olecranon fractures and its fixation strategies. Indian J. Orthop. 56 , 1385–1393 (2022). Bhavani, P., Roy, M., Das, D., Dwidmuthe, S. & Raghute, S. Challenging open extraction of intraarticular intracapsular broken patellar cerclage wire adjacent to the medial femoral condyle following unsuccessful arthroscopic removal. Cureus 16 , e58455 (2024). Duan, C. & Cheng, J. [effectiveness of three-needle and two-cable structure in treatment of inferior patellar pole avulsion fractures]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi . 39 , 686–691 (2025). Xie, M. et al. [effectiveness of multidirectionally three-dimensional steel wire ring sleeve fixation in treatment of inferior patellar pole avulsion fractures]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi . 35 , 183–187 (2021). Jang, J. H., Cho, Y. J., Choi, Y. Y. & Rhee, S. J. Hammock plating for comminuted inferior sleeve avulsion fractures of the patella: a surgical technique and clinical results. Orthop. Traumatol. Surg. Res. 107 , 102866 (2021). Tsubosaka, M., Makino, T., Kishimoto, S. I. & Yamaura, K. A case report of sleeve fracture of the patella in a shield. J. Orthop. Case Rep. 6 , 24–27 (2016). Veselko, M. & Kastelec, M. Inferior patellar pole avulsion fractures: osteosynthesis compared with pole resection. Surgical technique. J. Bone Joint Surg. Am. 87 (Suppl 1), 113–121 (2005). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 13 Apr, 2026 Reviews received at journal 12 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviews received at journal 06 Mar, 2026 Reviewers agreed at journal 05 Mar, 2026 Reviewers invited by journal 05 Mar, 2026 Editor assigned by journal 05 Mar, 2026 Editor invited by journal 03 Mar, 2026 Submission checks completed at journal 27 Feb, 2026 First submitted to journal 27 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8831920","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":602613089,"identity":"4db0c007-c4c8-4f3a-bb10-df7453de60fd","order_by":0,"name":"Taotao Ren","email":"","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":false,"prefix":"","firstName":"Taotao","middleName":"","lastName":"Ren","suffix":""},{"id":602613090,"identity":"1ed2accb-a7f0-43d9-8837-bc7131db5a6a","order_by":1,"name":"Bing Du","email":"","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bing","middleName":"","lastName":"Du","suffix":""},{"id":602613091,"identity":"7bc5793e-e1ba-4fa9-9a9a-0cef771e3757","order_by":2,"name":"Bo Wu","email":"","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":false,"prefix":"","firstName":"Bo","middleName":"","lastName":"Wu","suffix":""},{"id":602613092,"identity":"1b345d34-323c-401d-affe-3004b8e8fe43","order_by":3,"name":"Shuai Ji","email":"","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":false,"prefix":"","firstName":"Shuai","middleName":"","lastName":"Ji","suffix":""},{"id":602613093,"identity":"c3e93385-92e1-44ea-a404-e5667700a923","order_by":4,"name":"Yao Lu","email":"","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yao","middleName":"","lastName":"Lu","suffix":""},{"id":602613094,"identity":"14b117f3-a787-4752-97a9-7b91e44e3980","order_by":5,"name":"Zhong Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8UlEQVRIiWNgGAWjYDCCG4wNBhIGNsyM8w82PvhgYCNHhBbmhgKLijR25hnMzYYzCtKMidDC3vCh4sxhfvYZ7G3SPB8OJxLUwXe7sXHDzbY0ad7ZjQ3SNgbMCQzsh49uwKdF8s7BZsOZbTbGknMONhjnGLDlMfCkpd3Ap8XgRmKbsWRbWrJhQ2JDco4BTzGDBI8ZIS3tv/+2Ha7ffyCx4bCFgURiAxFagIF85jAz44zExmYGAwPCWoB+AWqpSGNm7DnYzNhjkGDMRsgvfLfbH0Cisr39+Y8ff/7L8bMfPoZXCyZgI035KBgFo2AUjAJsAAAMW1VB5lN+JQAAAABJRU5ErkJggg==","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":true,"prefix":"","firstName":"Zhong","middleName":"","lastName":"Li","suffix":""},{"id":602613095,"identity":"a437eab9-3bf6-41ac-8c02-209efdc8f1c0","order_by":6,"name":"Ming Li","email":"","orcid":"","institution":"Xi'an Medical University Affiliated Honghui Hospital: Honghui Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ming","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2026-02-09 15:10:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8831920/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8831920/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104416199,"identity":"e8e5be11-25b5-418b-bf22-a62a06ca8bb1","added_by":"auto","created_at":"2026-03-11 13:14:28","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":28409,"visible":true,"origin":"","legend":"\u003cp\u003eThe interception sites of different fracture lines.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/51e934619b53360606d61fb4.jpg"},{"id":104416286,"identity":"8e485796-3d62-4a2b-8e95-36055266a44a","added_by":"auto","created_at":"2026-03-11 13:14:41","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":172184,"visible":true,"origin":"","legend":"\u003cp\u003eModel after Meshing.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/699e2ba1b82c40faaa76f6bc.jpg"},{"id":104416191,"identity":"03d972ed-17da-4ff6-aaa2-b010aa3027d0","added_by":"auto","created_at":"2026-03-11 13:14:24","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":186354,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative situation of anchor loop plate in the treatment of sleeve avulsion fracture of the inferior pole of the patella. A. Incision exposure fracture line. B. Cut a small incision at the patellar ligament with a scalpel. C. One end of the long arm of the pre-bending plate passes through the patellar ligament hole. D and E. The plastic bone plate was inserted into the steel wire, and the lumbar puncture needle was assisted after fracture reduction. F. Screw implantation. G. Immediate joint passive flexion and extension activities. H and I. Intraoperative fluoroscopy.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/318f912c640b0ca77d331c8d.jpg"},{"id":104416207,"identity":"9dc65f24-fce4-4256-9e81-c96853a4d361","added_by":"auto","created_at":"2026-03-11 13:14:31","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":128776,"visible":true,"origin":"","legend":"\u003cp\u003eGeneral displacement distribution of different fracture line models : I-degree of the lower pole bone, K-wire group ( A ) and ALP group ( B ); Ⅱ-degree of the lower pole bone, K-wire group ( C ) and ALP group ( D ); Ⅲ-degree of the lower pole bone K-wire group ( E ) and ALP group ( F ).\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/d1bd2c1e053422619ab79de3.jpg"},{"id":104416488,"identity":"38009be6-f53e-4c73-969e-ec0e45e70aee","added_by":"auto","created_at":"2026-03-11 13:15:27","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":147777,"visible":true,"origin":"","legend":"\u003cp\u003eInternal fixation stress distribution of different fracture line models : I-degree of the lower pole bone, K-wire group ( A ) and ALP group ( B ); Ⅱ-degree of the lower pole bone, K-wire group ( C ) and ALP group ( D ); Ⅲ-degree of the lower pole bone, K-wire group ( E ) and ALP group ( F ).\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/946fc9d855ccd6ddbb7955e4.jpg"},{"id":104416343,"identity":"9912dc4e-ba33-41c8-95e2-4ffe3cb56bec","added_by":"auto","created_at":"2026-03-11 13:14:59","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":104084,"visible":true,"origin":"","legend":"\u003cp\u003eDifferent fracture line model of the inferior pole of the patella bone distribution cloud : I-degree of the lower pole bone, K-wire group ( A ) and ALP group ( B ); Ⅱ-degree of the lower pole bone, K-wire group ( C ) and ALP group ( D ); Ⅲ-degree of the lower pole bone, K-wire group ( E ) and ALP group ( F ).\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/92245282ef68e77781c7a4a7.jpg"},{"id":104416511,"identity":"0120b331-44e6-4a66-b6c4-e9a93cee88ca","added_by":"auto","created_at":"2026-03-11 13:15:32","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":57922,"visible":true,"origin":"","legend":"\u003cp\u003eThe change trend of internal fixation displacement in the two groups.\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/44ee3065dd8fa5e368e58d0f.jpg"},{"id":104416294,"identity":"38062da4-0f8a-49ff-b9b6-9bfbbd1eb6a7","added_by":"auto","created_at":"2026-03-11 13:14:45","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":78959,"visible":true,"origin":"","legend":"\u003cp\u003eThe trend of stress change of lower pole bone in two groups of internal fixation.\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/8a83d1de8e297c7662af3f32.jpg"},{"id":104416198,"identity":"b9e1c735-0516-413b-a50a-5391a354c24d","added_by":"auto","created_at":"2026-03-11 13:14:28","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":67171,"visible":true,"origin":"","legend":"\u003cp\u003eA 37-year-old male patient with an sleeve avulsion fracture of the inferior pole of the patella of the left patella caused by a falling injury. Preoperative CT ( A, B ), postoperative anteroposterior and lateral X-ray films ( C, D ), and knee joint function ( E, F ) 1 year after operation.\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/b88e299860ccbf6babd1b037.jpg"},{"id":104417689,"identity":"32e25587-4980-470b-a7e8-4bd4150fe99d","added_by":"auto","created_at":"2026-03-11 13:20:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1886521,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8831920/v1/cefb75d4-a534-40c4-b54f-0e67c0fedebc.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Anchor loop plate fixation for the treatment of sleeve avulsion fracture of the inferior pole of the patella : finite element analysis and case series","fulltext":[{"header":"Background","content":"\u003cp\u003eSleeve avulsion fracture of the inferior patellar pole is a serious injury involving the inferior patellar pole and the starting point of the patellar ligament. It is a special type of fracture of the knee extension device\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e .The injury mechanism is complex and often involves the destruction of the bone-cartilage-ligament complex, which is relatively common in children and adolescents, especially in pre-adolescent men who participate in high-intensity exercise\u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e.Since the inferior pole of the patella is the hub of the quadriceps contraction force transmitted to the tibial tubercle through the patellar ligament, such fractures directly destroy the continuity of the mechanical conduction of the lower limbs. Improper treatment can easily lead to serious complications such as knee extension dysfunction, patella low, and traumatic arthritis\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. The overall treatment strategy of avulsion fracture of the inferior pole of the patella mostly depends on surgical fixation. However, due to the variable fracture line and poor bone conditions, the selection of surgical options and the optimization of fixation methods are still controversial. The existing research mainly focuses on the clinical application and efficacy evaluation of traditional fixation methods, such as Kirschner wire tension band fixation and plate fixation. Their respective advantages and disadvantages and application scope have been preliminarily clarified\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. However, there is still a lack of systematic analysis of the biomechanical properties of different fracture lines in the inferior pole of the patella, especially the mechanical stability and clinical safety of the new fixation technology. In addition, the existing literature is mostly case reports or small sample reviews, and there is a lack of comprehensive research combining finite element analysis and clinical large sample data, which limits the clinical promotion and application of related technologies.\u003c/p\u003e \u003cp\u003eIn view of the above shortcomings, this study innovatively combines finite element analysis with clinical case treatment reports to construct avulsion fracture models of the inferior patellar pole under different fracture line distributions, and quantitatively evaluates the biomechanical properties of the new anchor loop plate fixation technique. The finite element method simulates the changes of the force of the avulsion fracture of the inferior pole of the patella under different fracture lines, and compares it with the traditional fixation method, which provides a mechanical stability reference for the optimization of the surgical fixation method. At the same time, combined with the clinical case series, this study systematically reviewed the application effect and safety of the anchor loop plate in the actual operation. Combining biomechanical research with clinical research, the division of different fracture lines reflects the trend from simple inferior patellar fracture to sleeve avulsion fracture fixation, which provides a new idea for the treatment of sleeve avulsion fracture of inferior patellar pole.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eFinite element analysis: collection of imaging data\u003c/h2\u003e \u003cp\u003eA 35-year-old male patient with a patellar fracture ( voluntary informed consent ) weighing 70 kg was selected. X-ray examination showed that there was no lesion in the contralateral patella, and the bone was good. A Spiral CT scan was performed. The scanning target was the healthy patella of the patient. The scanning length was from 5 cm above the upper pole of the patella to 5 cm below the lower pole of the patella. The scanning conditions were 120 k V, 155 m A, and the scanning layer thickness was 1 mm. The scanning information was collected and processed, and the continuous image data was saved in DICOM format. This study was approved by the Ethics Committee of Xi 'an Red Cross Hospital, and all the research methods in this study are implemented in accordance with the relevant guidelines and regulations.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eFinite element model of patella construction\u003c/h3\u003e\n\u003cp\u003eThe data were imported into Mimics15.0 software, and the rough model of the femur was established by the commands of threshold segmentation and region growth in the software. Import it into Geomagic 2017 software. The model is subdivided into triangular patches, noise reduction and smoothing. Three-dimensional models of patellar cancellous bone and cortical bone were constructed by precise surface treatment. The above model was imported into Solidworks software, and the patella was divided into 16 equal parts from the upper pole to the lower pole. In the lower pole area of the patella, three fracture lines were constructed to divide the lower pole area of the patella into four equal parts. The 3 / 16 fracture line was defined as I-degree fracture of the lower pole of the patella, 2 / 16 fracture line was defined as II-degree fracture of the lower pole of the patella, and 1 / 16 fracture line was defined as III-degree fracture of the lower pole of the patella, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The schematic diagram of different fracture lines of the inferior pole of the patella is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.The experiment was divided into two groups: A.Kirschner wire group: Two Kirschner wires parallel to the articular surface of the patella were inserted into the patella, bound with steel wire ' 8 ', and the surface of the patella was bound with steel wire. B. Anchor loop plate ( ALP ) group: After the microplate was bent, it was attached to the surface of the patella through the patellar ligament and fixed with three screws and one steel wire.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eVolume mesh generation\u003c/h3\u003e\n\u003cp\u003eFinite element models were constructed using linear tetrahedrons(Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This study showed 463524 elements with 628437 nodes in the tension band model after meshing and 258748 elements with 346795 nodes in the microplate model. The specific values are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eNumber of nodes and elements in finite element model\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eNumber of nodes and elements in finite element model\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eFinite element model Nodes Elements\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eA group (K-wire)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e628437\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e463524\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eB group(ALP)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e346795\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e258748\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eAssignment of material properties\u003c/h3\u003e\n\u003cp\u003eThe relevant material properties of the finite element model of patellar fracture were set up, and a three-dimensional finite element model similar to the actual model in terms of material parameters and mechanical behavior was established. The ligament is set to be a linear elastic material that only bears tensile stress. According to the actual data of clinical internal fixation device, the internal fixation structure involved in this study was constructed by Solidworks software, and the material properties of patellar cortical bone, patellar cancellous bone, Kirschner wire, steel wire and titanium alloy ( plate and screw ) were set \u003csup\u003e[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. The specific parameters are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, and then the three-dimensional model and internal fixation model of the lower patella fracture with different fracture lines are assembled in SolidWorks software.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eModel material parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eName of the material\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eElastic modulus(MPa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePoisson ratio\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCortical bone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCancellous bone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e840\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSteel wire\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKirschner wire\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e200000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTitanium alloy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e110000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eConstraint and loading\u003c/h3\u003e\n\u003cp\u003eTwo groups of three-dimensional finite element models with different fracture lines were fixed in the inferior patellar fracture models. A force of 0-500 N was applied to the inferior surface of the patella within 1 s\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eClinical data\u003c/h2\u003e \u003cp\u003eFrom June 2018 to June 2022, a total of 57 patients with patellar inferior pole fracture were treated, of which eight patients with patellar inferior pole avulsion fracture met the inclusion and exclusion criteria and received anchor loop plate surgery. There were five males and three females. The ages ranged from 45 to 76 years, with an average age of 58.38 years. Six cases were caused by falls, and two cases were caused by traffic accidents. The hospital ethics committee has approved this experiment, and all patients have signed the informed consent. Inclusion criteria: 1. CT diagnosis of sleeve avulsion fracture of the inferior pole of the patella; 2.Fixed with the anchor loop plate ; 3. New fractures were completed within one week after injury; 4. Knee joint function was good before injury; 5. Patients informed consent and complete clinical data. Exclusion criteria are as follows: 1. Patients with other types of patellar fractures; 2.Patients with distal femoral fractures or proximal tibial fractures ; 3. Combined with patellar fracture or patellar ligament injury; 4. patients treated with other fixation methods; 5. Lost follow-up or follow-up less than nine months.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurgical procedure\u003c/h3\u003e\n\u003cp\u003eAfter the patient's anesthesia was satisfied, the supine position was taken, routine disinfection was performed, a sterile surgical scarf was spread, and the tourniquet was placed close to the thigh. During the operation, the sleeve avulsion fracture of the inferior pole of the patella block was exposed by the median anterior approach, the joint cavity was rinsed, and the blood clots around the joint and at the fracture end were removed. A small incision was made at the junction of the patellar ligament, and the lower pole with a sharp knife, and the long arm of the plate passed through the patellar ligament from the inside to the outside. Then, the short arm of the plate was dragged to the lower pole of the patella, and the plate was adjusted with the help of the fluoroscopy machine to attach to the surface of the patella. After satisfactory forming, the steel wire is penetrated. Once again, the long arm of the steel plate passes through the small incision of the patellar ligament from the inside to the outside, dragging the lower pole bone block to reset. When the local bone block is squeezed, the lower bone piece can be sutured with a suture line, and the whole is sutured to the short arm hole of the anchor plate. Lumbar puncture needle assisted wire puncture, through the inner and outer support band and soft tissue, wire ring tightened. ( wire diameter is 1 mm ). Then the plate was fixed with 2.7 screws. Knee flexion was performed during the operation to check fracture stability. Rinse the wound repeatedly with plenty of normal saline. Suture the patellar ligament incision, align the flap suture, and suture the skin layer by layer. The knee joint passive flexion and extension activities were observed and recorded immediately. The key steps in the operation are shown in Fig.\u0026nbsp;3.\u003cdiv description=\"\" class=\"Drawing\" id=\"1341584651\" name=\"图片 1\"\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;3. Intraoperative situation of anchor loop plate in the treatment of sleeve avulsion fracture of the inferior pole of the patella. A. Incision exposure fracture line. B. Cut a small incision at the patellar ligament with a scalpel. C. One end of the long arm of the pre-bending plate passes through the patellar ligament hole. D and E. The plastic bone plate was inserted into the steel wire, and the lumbar puncture needle was assisted after fracture reduction. F. Screw implantation. G. Immediate joint passive flexion and extension activities. H and I. Intraoperative fluoroscopy.\u003c/p\u003e\n\u003ch3\u003eOutcome measures\u003c/h3\u003e\u003cp\u003eOn the second day after the operation, the dressing was opened to observe the wound, the wound was disinfected strictly, and the dressing was replaced. The X-ray and CT films of the knee joint were retrospectively analyzed. Actively carry out the flexion and extension of the knee joint, and the movement angle gradually increases ( the target angle of movement is 90 \u0026deg; 1 week after surgery ). Half-weight-bearing training was started one day after the operation, and full-weight-bearing training was carried out one month after the operation. X-ray films of affected limbs were reviewed every four weeks after the operation to evaluate fracture healing, guide patients to carry out knee joint functional exercises, record knee joint activity, and record surgical complications. Fracture healing was based on X-ray examination results and clinical results. X-ray examination showed that the fracture healed. The clinical results showed that the patient could walk normally without knee pain, and the fracture was healed. The knee joint function score was evaluated by the Bostman score\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eFinite element analysis: displacement of fractures\u003c/h2\u003e \u003cp\u003eOn the second day after the operation, the dressing was opened to observe the wound, the wound was disinfected strictly, and the dressing was replaced. The X-ray and CT films of the knee joint were retrospectively analyzed. Actively carrying out the flexion and extension of the finite element analysis under 500 N load of different fracture lines is as follows. The biomechanical test results of the finite element model showed that the maximum displacement of the K-wire group and the ALP group at the I-degree of the lower pole bone was 0.122 mm and 0.069 mm, respectively. The maximum displacement of the K-wire group was 1.77 times that of the ALP group. The maximum displacement of the K-wire group and the ALP group at the Ⅱ-degree of the lower pole bone was 0.173 mm and 0.078 mm, respectively. The maximum displacement of the K-wire group was 2.22 times that of the ALP group. The maximum displacement of the K-wire group and the ALP group at the Ⅲ-degree of the lower pole bone was 0.288 mm and 0.084 mm, respectively. The maximum displacement of the K-wire group was 3.43 times that of the ALP group, as shown in Fignnnnnnure 4. With the movement of the fracture line to the lower pole of the patella, the advantage of the ALP group in maintaining stable reduction was more significant.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFinite element analysis results.\u003c/b\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eFinite element analysis: Internal fixation and stress distribution of inferior patella pole\u003c/h2\u003e \u003cp\u003eThe maximum internal fixation stress of the K-wire group and the ALP group showed that the I-degree of the lower pole bone was 587.35 MPa and 485.67 MPa, respectively, and the maximum stress of the Kirschner wire group was 1.21 times that of the ALP group. The maximum stress at the Ⅱ-degree of the lower pole bone was 73.26 MPa and 511.65 MPa, respectively. The maximum stress in the Kirschner wire group was 1.53 times that in the ALP group. The maximum stress at the Ⅲ-degree of the lower pole bone was 856.80 MPa and 536.94 MPa, respectively. The maximum stress of the Kirschner wire group was 1.60 times that of the ALP group. The maximum stress of the polar bone in the K-wire group and the ALP group showed that the I-degree of the lower pole bone was 77.26 MPa and 5.81 MPa, respectively. The maximum stress of the polar bone in the K-wire group was 13.30 times that of the ALP group in the Ⅰ-degree of the lower pole bone. The maximum stress of the polar bone in the K-wire group was 15.34 times that of the ALP group in the Ⅱ-degree of the lower pole bone. The maximum stress of polar bone in the K-wire group was 16.86 times that of the ALP group in the Ⅲ-degree of the lower pole bone. The stress concentration is distributed at each contact point between the internal fixation and the polar bone. The overall stress situation of the ALP group is stable at a lower level. As the fracture line moves to the lower pole of the patella, the smaller the peak value of the stress distribution in the ALP group, the more significant the advantage. The two sets of finite element analysis cloud images are shown in Fig.\u0026nbsp;5 and Fig.\u0026nbsp;6.\u003cdiv description=\"\" class=\"Drawing\" id=\"18\" name=\"图片 18\"\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003eThe peak displacement and peak stress of the two internal fixation schemes.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eComparing the peak displacement and peak stress values of the K-wire group and the ALP group, the overall peak displacement and peak stress of the ALP group were at a lower level than those of the K-wire group. In particular, the stress of the patella lower pole bone block in the ALP group was significantly lower than that in the K-wire group. As the fracture line moves to the distal end of the patella, the ALP changes less, while the K-wire group is affected by the fracture line. The change of the distal movement is greater, which indicates that the ALP group has a more stable biomechanical structure, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e7\u003c/span\u003e and Fig.\u0026nbsp;8.\u003cdiv description=\"\" class=\"Drawing\" id=\"14\" name=\"图表 14\"\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eClinical outcome\u003c/h2\u003e \u003cp\u003eThe 8 cases of sleeve avulsion fracture of the inferior pole of the patella included in the study were well-healed without serious complications such as internal fixation failure or infection. The average operation time was 81.87 min ( 72\u0026ndash;87 min ), the average final knee range of motion ( ROM ) was 124.50 \u0026deg; ( 118 \u0026deg; -130 \u0026deg; ), the average Bostman score was 26.38 ( 24\u0026ndash;29 ) at the third month, and the average Bostman score was 28.63 ( 27\u0026ndash;30 ) at the ninth month. All patients showed good knee function one year after the operation. The typical case is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e9\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003e \u003cb\u003e1.Special anatomical structure and treatment of patellar sleeve avulsion fracture\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe inferior pole of the patella is the starting point of the patellar ligament, and its anatomical structure is special. The trabecular bone structure in this area is unique and the blood supply is relatively weak, making it a stress concentration area in the knee extension device. This anatomical feature makes the lower pole of the patella prone to injury when subjected to strong traction. In particular, the transition zone between the patellar ligament and the lower pole of the patella is a mechanically weak point. When the knee joint is subjected to acute violence or chronic overload, this area is prone to avulsion fractures with cartilage or thin bone slices as the ' cap ', while the ligament substance itself may remain relatively intact\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. The integrity of the knee extension device is essential for maintaining normal knee function. It not only ensures the normal mechanical trajectory of the patellofemoral joint, but also plays a decisive role in the extension of the knee joint within 30 °\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. The choice of surgical treatment strategy for sleeve avulsion fracture of the lower pole of the patella lies in the accurate evaluation of the nature of the injury, the state of the fracture block and the soft tissue conditions. For patients with old fracture nonunion or malunion, due to the presence of fibrous tissue or callus between the fracture ends, and often accompanied by knee extension device shortening and joint stiffness, simple internal fixation is often difficult to obtain stable healing and good function. At this time, the operation should be based on the integrity of the patellar ligament to determine whether reconstruction is needed after fully releasing the joint adhesion and restoring the normal position and height of the patella\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e.When considering surgical treatment, both the internal fixation of the inferior pole of the patella fracture and the reconstruction of the patellar ligament must be aimed at restoring the natural anatomy and biomechanics of the knee joint\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003cb\u003e2.New internal fixation technology strategy for sleeve avulsion fracture of the lower pole of the patella\u003c/b\u003e \u003c/p\u003e \u003cp\u003eTension band fixation is a classic method for the treatment of patellar fractures, especially non-comminuted fractures. Its core biomechanical principle is to convert the tension acting on the anterior surface of the patella in the flexion and extension of the knee joint into the pressure at the fracture end, thereby promoting fracture healing\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. However, before the application of tension band technology, the quality of bone block must be carefully evaluated to ensure that it can withstand the cerclage force of steel wire and avoid the fixation failure caused by insufficient holding force\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. The lower pole of the patella is avulsion fracture, usually the bone block is small, and the tension band fixation technique is difficult to provide sufficient holding force. For the innovation of tension band technology, some scholars have proposed the ' three needles and two cables ' structure for the treatment of avulsion fracture of the inferior pole of the patella. Compared with the traditional steel wire tension band, this technology shortens the operation time, reduces the incidence of complications, and obtains better knee joint mobility and functional score\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. However, for comminuted fractures or sleeve avulsion fractures, it is often difficult to obtain strong internal fixation by conventional tension band and tension band-related modified techniques. Suture anchors and suture bridge fixation techniques have become one of the mainstream minimally invasive fixation methods for the treatment of sleeve avulsion fractures of the lower pole of the patella, especially in cases of small bone mass, crushing or osteoporosis. The core of this technique is to implant suture anchors into the proximal bone of the lower pole of the patella, and use high-strength sutures to weave or bridge avulsed bone-ligament complex\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. In recent years, with the in-depth exploration of internal fixation for the treatment of avulsion fracture of the lower pole of the patella, it is difficult to grasp the bone fixation for the avulsion fracture of the lower pole of the patella. Scholars have explored a variety of surgical methods to solve this traumatic orthopedic problem. For example, multi-directional three-dimensional steel wire ring fixation technology has been proved to have the advantages of reliable fixation, allowing early functional exercise and fewer complications\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. A new type of implant was designed based on the principle of biomechanics, such as the ' smile necklace ' plate, which has the advantages of both plate fixation and tension band fixation. It aims to provide better fixation for osteoporotic comminuted fractures and facilitate early rehabilitation\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. In addition, a ' hammock plate ' technique using synthetic sutures and low-profile mini-plates to form a ' hammock ' -like structure to lift bone blocks as a whole has also been proposed for comminuted lower pole sleeve avulsion fractures, aiming to achieve firm bone healing\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003cb\u003e3.The expected effect, biomechanical and clinical results of surgical treatment of avulsion fracture of the inferior pole of the patella.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eSince the location of the avulsion fracture of the lower pole of the patella does not involve the patellofemoral joint surface and does not require anatomical reduction of the articular surface, the main goal of treatment is to restore the knee extension device. The results of finite element analysis showed that under the same 500 N tensile load, the ALP group of different fracture lines showed smaller maximum displacement and smaller internal fixation stress in the comparison of different fracture lines, that is, in the I-degree, II-degree and III-degree of patellar inferior pole fracture, showing better biomechanical stability than the Kirschner wire group.The two groups have a massive gap in the stress of the lower pole fracture. ALP fixation will bring a more minor stress to the lower pole bone, while K-wire fixation will bring a more significant and more concentrated stress to the lower pole bone. Through further analysis of the data, we found that as the fracture line is closer to the distal end of the lower pole, the biomechanical stability of the K-wire group becomes more unstable during this dynamic change.In contrast, the displacement and stress of the ALP group remain at a low level and are less affected by the change of the fracture line, as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e and Fig.\u0026nbsp;8. From the perspective of biomechanical stability, this shows that the smaller the lower pole fracture block after the lower pole fracture of the patella, the more prominent the advantages of the ALP group fixation method. The clinical results showed that the average Bostman score nine months after surgery reached 28.63, and the final knee range of motion ( ROM ) was 124.50 ° on average, indicating that the knee function of patients undergoing ALP fixation recovered well after surgery.\u003c/p\u003e \u003cp\u003e \u003cb\u003e4. The biomechanical properties of ALP are better when the fracture of the inferior pole of the patella is fixed with different fracture lines.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe results of statistical finite element mechanical analysis showed that as the fracture line of the lower pole of the patella moved down, the biomechanical trends of the two internal fixations were as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e and Fig.\u0026nbsp;8. During the transformation of the fracture type from I-degree fracture of the lower pole of the patella to III-degree fracture of the lower pole of the patella, ALP was more stable in the three aspects of overall displacement, internal fixation stress and lower pole bone stress, and ALP fixation with the fracture line moved down, the change range was small, while the Kirschner wire tension band group changed greatly. As the fracture line tends to be larger than the III-degree of inferior patellar fracture, it is suggested that this method is not suitable for the treatment of avulsion fracture of the inferior patellar pole. In the dynamic process of moving down the fracture line, we noticed that the 8-shaped structure of the Kirschner wire tension band group was shrinking, and the contact surface between the Kirschner wire and the lower pole of the bone block was also shrinking rapidly. Perhaps due to the smaller contact area, the local pressure was greater, which made the biomechanical structure tend to be unstable. With the dynamic process of the fracture line moving down, we noticed that the area of the short arm of the plate in the stress concentration area was almost unchanged, which brought about a more stable structure. The severity of the fracture of the inferior pole of the patella was less changed, and its biomechanical stability was very stable. The application of ALP in the treatment of sleeve avulsion fracture of the inferior pole of the patella provides a confirmation of biomechanical stability.\u003c/p\u003e "},{"header":"conclusion","content":"\u003cp\u003eIn our previous study, it has been confirmed from the perspective of clinical and biomechanical that ALP uses the inferior pole of the patella and the patellar ligament as a whole towing technique, which can be used as a new method for the treatment of the inferior pole of the patella fracture, and has achieved excellent research results. In view of the excellent biomechanical advantages of ALP, in order to further expand its application, the research team applied it to the treatment of more extreme sleeve avulsion fracture of the lower pole of the patella. In this special, difficult and technically demanding fracture of the lower pole of the patella, and achieved good clinical prognosis.The sleeve avulsion fracture of the inferior pole of the patella is indeed a more difficult fracture of the inferior pole of the patella. Because the sleeve avulsion fracture is a relatively rare type of patellar fracture, the existing studies usually only have relevant cases to report this type of patellar fracture, such as the case report of Shimasaki and Tsubosaka on the sleeve avulsion fracture\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. Due to the inability to use tension band technology to fix, they use sutures to fix the fracture of the lower pole of the patella. The fixation strength is low, and there is no internal fixation device suitable for this unique patellar fracture. Most scholars use the surgical method of patellar ligament reconstruction, but patellar ligament reconstruction often has complications such as patellar height change and patellofemoral arthritis.However, some scholars have found that compared with the patellar ligament repair with the removal of the inferior pole of the patella, the preservation of the inferior pole of the patella usually does not cause the abnormal position of the patella after the operation, and the connection strength between the bone and the bone is greater than that between the bone and the ligament\u003csup\u003e[\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. It enables patients to carry out early functional exercise and obtain better knee joint function. On the basis of retaining the advantages of bone-bone fixation, the screw hole design of ALP can be used as a suture site. In the case of patellar ligament tear, the suture can be fixed on the ALP after the patellar ligament is repaired by the suture, and the continuity of the patellar ligament can be indirectly restored. In this study, the finite element model was used to confirm that for the sleeve-shaped avulsion fracture of the patella, due to the very small amount of bone in the lower pole, the more concentrated the stress of the internal fixation on the bone block, the higher the probability of internal fixation failure. As the fracture line is closer to the distal end of the fracture, the smaller the bone block in the lower pole of the patella, and the tension band combined with the patella cerclage technique is difficult to stabilize. This is confirmed in the finite element analysis part of this study. Further finite element mechanical analysis results show that as the fracture line is closer to the distal end of the fracture, the smaller the bone block at the lower pole of the patella is, and the tension band combined with the patellar cerclage technique is difficult to stabilize. Fixed, and ALP technology is not affected by the fracture line, when the fracture block is small, its biomechanical stability is still good. Therefore, we applied ALP technology to the treatment of clinical patellar lower pole sleeve avulsion fracture, and obtained better clinical treatment effect, which provided a new surgical fixation idea for the special type of patellar lower pole sleeve avulsion fracture.In addition, in most cases, the failure of internal fixation in patients with the lower pole of the patella usually indicates that the volume of the lower pole bone block that can be used for fixation during the second revision surgery will be further reduced. The reduction of bone mass will make the internal fixation device unable to be fixed and be treated with patellar ligament reconstruction. We found that compared with the improved tension band technique, the biomechanical stability of the ALP device did not fluctuate significantly with the further reduction of the remaining bone volume. Therefore, the ALP device has the advantage of potentially stable fixation for the failure of the internal fixation in the first operation. We applied this technique to the failure of the internal fixation device and tried to perform secondary surgical fixation to obtain a better surgical treatment effect.\u003c/p\u003e"},{"header":"Shortcomings of current research","content":"\u003cp\u003eALP has better biomechanical stability than modified tension band in the treatment of patellar inferior pole fractures with different fracture lines, and better recovery of knee joint function after operation, which is more prominent in the fixation of patellar inferior pole avulsion fractures. Anchor loop plate is an effective surgical method for the treatment of patellar inferior pole fracture, which brings new possibilities for the fixation of patellar inferior pole sleeve avulsion fracture. The limitations of this study are mainly reflected in the insufficient sample size and the lack of long-term follow-up data. The limitation of sample size may lead to insufficient statistical significance of the results, which affects the general applicability of the research conclusions. In addition, the finite element analysis used in this study simplifies the connection structure. The influence of soft tissues such as ligaments and muscles around the knee joint on mechanical stability was ignored. These soft tissues may cause specific errors, and further mechanical experiments are needed to verify our research results.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAnnouncement : \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll patients with identifiable human images in this article have informed consent and signed consent for this study.All participants, including patients and researchers who participated in the study, agreed to the release of this study.\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eSupported by the Shaanxi Provincial Science and Technology Department(No. 2025JC-YBQN-1238) and (No. 2025SF-YBXM-089).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eT.T.Ren and M.Li are responsible for the conception and writing of the article. B.Wu and S.Ji are responsible for consulting the relevant literature. B.Du is responsible for finite element analysis experiments. Y.Lu and Z.Li were responsible for manuscript proofreading and clinical CT data collection.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eShimasaki, K., Uesugi, M., Kobayashi, T., Tanaka, H. \u0026amp; Ichimura, H. Inferior pole sleeve fracture of the patella in an adolescent: a case report. \u003cem\u003eCureus\u003c/em\u003e \u003cb\u003e15\u003c/b\u003e, e33494 (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDesai, V. M., DeFrancesco, C. J., Yellin, J. L., Nguyen, J. C. \u0026amp; Williams, B. A. Patient characteristics and postoperative outcomes of surgically treated inferior pole patellar sleeve fractures. \u003cem\u003eJ. Pediatr. Orthop.\u003c/em\u003e \u003cb\u003e44\u003c/b\u003e, 483\u0026ndash;488 (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu, W. et al. Design and validation of a smile-necklace plate for treating inferior patellar pole avulsion fractures: a review and hypothesis. \u003cem\u003eOrthop. Surg.\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e, 2799\u0026ndash;2808 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim, K. S. et al. Suture anchor fixation of comminuted inferior pole patella fracture-novel technique: suture bridge anchor fixation technique. \u003cem\u003eArch. Orthop. Trauma. Surg.\u003c/em\u003e \u003cb\u003e141\u003c/b\u003e, 1889\u0026ndash;1897 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNowell, J. A. \u0026amp; Niu, E. L. Patellar sleeve avulsion fracture repair: suture anchor technique with suture cerclage augmentation. \u003cem\u003eArthrosc. Tech.\u003c/em\u003e \u003cb\u003e12\u003c/b\u003e, e2197\u0026ndash;e2202 (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWood, R., Krumrey, J., Palomino, K. \u0026amp; Hicks, M. Suture anchor repair for distal patellar tendon avulsion in tibial tubercle fractures: a technical description and report of two cases. \u003cem\u003eCureus\u003c/em\u003e \u003cb\u003e16\u003c/b\u003e, e54696 (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLing, M., Zhan, S., Jiang, D., Hu, H. \u0026amp; Zhang, C. Where should kirschner wires be placed when fixing patella fracture with modified tension-band wiring? A finite element analysis. \u003cem\u003eJ. Orthop. Surg. Res.\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e, 14 (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeng, D., Ouyang, Y. \u0026amp; Hou, C. [a finite element analysis of petal-shaped poly-axial locking plate fixation in treatment of y-shaped patellar fracture]. \u003cem\u003eZhongguo Xiu Fu Chong Jian Wai Ke Za Zhi\u003c/em\u003e. \u003cb\u003e31\u003c/b\u003e, 1456\u0026ndash;1461 (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim, Y., Kwon, M., Ryu, J. Y. \u0026amp; Moon, S. W. Biomechanical analysis of the kirschner-wire depth of the modified tension band wiring technique in transverse patellar fractures: an experimental study using the finite-element method. \u003cem\u003eClin. Orthop. Surg.\u003c/em\u003e \u003cb\u003e13\u003c/b\u003e, 315\u0026ndash;319 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe, S. et al. Modified technique of separate vertical wiring for the fixation of patellar inferior pole fracture. \u003cem\u003eJ. Orthop. Trauma.\u003c/em\u003e \u003cb\u003e32\u003c/b\u003e, e145\u0026ndash;e150 (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eB\u0026ouml;stman, O., Kiviluoto, O. \u0026amp; Nirhamo, J. Comminuted displaced fractures of the patella. \u003cem\u003eInjury\u003c/em\u003e \u003cb\u003e13\u003c/b\u003e, 196\u0026ndash;202 (1981).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNegr\u0026atilde;o, E., van den Eede, E., Kyriazopoulos, A. \u0026amp; Romijn, M. G. Sinding-larsen-johansson syndrome with minimally displaced patellar sleeve avulsion fracture: a case report with multimodality approach and literature review. \u003cem\u003eSkeletal Radiol.\u003c/em\u003e \u003cb\u003e52\u003c/b\u003e, 1403\u0026ndash;1407 (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFelli, L. et al. Anatomy and biomechanics of the medial patellotibial ligament: a systematic review. \u003cem\u003eSurgeon\u003c/em\u003e \u003cb\u003e19\u003c/b\u003e, e168\u0026ndash;e174 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElbaz, M. A., Batra, A., Mohamed, A., Alkhateeb, K. M. \u0026amp; Abdulgadir, M. Proximal patellar tendon injury with avulsed periosteal sleeve: a case report and long-term follow-up. \u003cem\u003eInt. J. Surg. Case Rep.\u003c/em\u003e \u003cb\u003e127\u003c/b\u003e, 110870 (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHargreaves, M., Sisson, H., Harris, C., Momaya, A. M. \u0026amp; Casp, A. J. Combined medial patellofemoral ligament and medial quadriceps tendon-femoral ligament reconstruction with single knotless anchor. \u003cem\u003eArthrosc. Tech.\u003c/em\u003e \u003cb\u003e13\u003c/b\u003e, 103102 (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMartin-Alguacil, J. L. et al. Double-bundle technique for the reconstruction of the proximal medial patellofemoral complex, using the first layer of the quadriceps tendon as a graft. \u003cem\u003eArthrosc. Tech.\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e, 103268 (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTan, B. Y., Ng, J., Ng, W. X., Wei, Y. \u0026amp; Kwek, E. The evolution of olecranon fractures and its fixation strategies. \u003cem\u003eIndian J. Orthop.\u003c/em\u003e \u003cb\u003e56\u003c/b\u003e, 1385\u0026ndash;1393 (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBhavani, P., Roy, M., Das, D., Dwidmuthe, S. \u0026amp; Raghute, S. Challenging open extraction of intraarticular intracapsular broken patellar cerclage wire adjacent to the medial femoral condyle following unsuccessful arthroscopic removal. \u003cem\u003eCureus\u003c/em\u003e \u003cb\u003e16\u003c/b\u003e, e58455 (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuan, C. \u0026amp; Cheng, J. [effectiveness of three-needle and two-cable structure in treatment of inferior patellar pole avulsion fractures]. \u003cem\u003eZhongguo Xiu Fu Chong Jian Wai Ke Za Zhi\u003c/em\u003e. \u003cb\u003e39\u003c/b\u003e, 686\u0026ndash;691 (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXie, M. et al. [effectiveness of multidirectionally three-dimensional steel wire ring sleeve fixation in treatment of inferior patellar pole avulsion fractures]. \u003cem\u003eZhongguo Xiu Fu Chong Jian Wai Ke Za Zhi\u003c/em\u003e. \u003cb\u003e35\u003c/b\u003e, 183\u0026ndash;187 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJang, J. H., Cho, Y. J., Choi, Y. Y. \u0026amp; Rhee, S. J. Hammock plating for comminuted inferior sleeve avulsion fractures of the patella: a surgical technique and clinical results. \u003cem\u003eOrthop. Traumatol. Surg. Res.\u003c/em\u003e \u003cb\u003e107\u003c/b\u003e, 102866 (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsubosaka, M., Makino, T., Kishimoto, S. I. \u0026amp; Yamaura, K. A case report of sleeve fracture of the patella in a shield. \u003cem\u003eJ. Orthop. Case Rep.\u003c/em\u003e \u003cb\u003e6\u003c/b\u003e, 24\u0026ndash;27 (2016).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVeselko, M. \u0026amp; Kastelec, M. Inferior patellar pole avulsion fractures: osteosynthesis compared with pole resection. Surgical technique. \u003cem\u003eJ. Bone Joint Surg. Am.\u003c/em\u003e \u003cb\u003e87\u003c/b\u003e (Suppl 1), 113\u0026ndash;121 (2005).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Patellar fractures, Plates, Sleeve avulsion fracture, Tension band, Finite Element Analysis","lastPublishedDoi":"10.21203/rs.3.rs-8831920/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8831920/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eThe purpose of this study was to compare the biomechanical stability of the Kirschner wire tension band combined with patellar cerclage and anchor loop plate ( ALP ) in the treatment of inferior patellar fracture with different fracture lines and to provide a new solution for the treatment of sleeve avulsion fracture of the inferior pole of the patella.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThe finite element model was established, and the lower pole fractures of different fracture block sizes were graded according to the distribution of the lower pole fracture line. The model was subjected to finite element mechanical test under 500 N pressure to test the biomechanical properties of Kirschner wire tension band combined with patellar cerclage anchor nail loop plate fixation for the treatment of patellar lower pole fractures with different fracture lines. The clinical data of 8 patients with sleeve avulsion fracture of the inferior pole of the patella admitted to our hospital from June 2018 to June 2022 were retrospectively analyzed. All patients were treated with a newly designed anchor loop plate. The safety and effectiveness of this new technique in the treatment of sleeve avulsion fracture of the inferior pole of the patella were analyzed. The safety activity of passive flexion and extension of the knee joint during the operation was observed by consulting the medical records and follow-up results. The fracture healing, knee function recovery and postoperative complications were observed. Bostman score was used to evaluate knee joint function 3 and 9 months after operation.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe biomechanical analysis of the finite element model showed that the maximum displacement of the Kirschner wire group was 1.77 times that of the ALP group at I-degree of the lower pole bone, the maximum stress of the Kirschner wire group was 1.21 times that of the ALP group, and the maximum stress of the Kirschner wire group was 13.29 times that of the ALP group. The maximum displacement of the II-degree of the lower pole bone in the Kirschner wire group was 2.22 times that of the ALP group, the maximum stress in the Kirschner wire group was 1.53 times that of the ALP group, and the maximum stress in the Kirschner wire group was 15.34 times that of the ALP group. The maximum displacement of the III-degree of the lower pole bone in the Kirschner wire group was 3.43 times that of the ALP group, the maximum stress in the Kirschner wire group was 1.60 times that of the ALP group, and the maximum stress in the Kirschner wire group was 16.86 times that of the ALP group. All avulsion fractures of the inferior patellar pole healed well without serious complications such as internal fixation failure or infection. The average operation time was 81.87 min ( 72\u0026ndash;87 min ), the average final knee range of motion ( ROM ) was 124.50 \u0026deg; ( 118 \u0026deg; -130 \u0026deg; ), the average Bostman score was 26.38 ( 24\u0026ndash;29 ) in the third month, and the average Bostman score was 28.63 ( 27\u0026ndash;30 ) in the ninth month. All patients showed good knee function one year after the operation.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eWith the change of fracture line to the distal end, the biomechanical stability of anchor loop plate was less affected by the change of fracture line, while the influence of Kirschner wire tension band combined with patellar cerclage technology tended to be unstable. Therefore, for sleeve avulsion fracture of the inferior pole of the patella, anchor loop plate has more biomechanical stability. In clinical practice, sleeve avulsion fracture of the inferior pole of the patella can be firmly fixed, and early functional exercise of knee joint can be allowed to bring good knee joint function to patients with sleeve avulsion fracture of the inferior pole of the patella.\u003c/p\u003e","manuscriptTitle":"Anchor loop plate fixation for the treatment of sleeve avulsion fracture of the inferior pole of the patella : finite element analysis and case series","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-11 12:00:58","doi":"10.21203/rs.3.rs-8831920/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-13T08:47:41+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-12T23:56:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"2752145437355514282002950500907130809","date":"2026-04-02T02:09:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-06T09:53:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"76459031371463741683296475861744938782","date":"2026-03-05T15:29:04+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-05T15:04:15+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-05T14:38:47+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-03T07:49:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-27T22:56:09+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-02-27T17:23:29+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d028aa56-20b6-4543-bdf9-55cca30396aa","owner":[],"postedDate":"March 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":64124685,"name":"Health sciences/Anatomy"},{"id":64124686,"name":"Health sciences/Diseases"},{"id":64124687,"name":"Health sciences/Medical research"}],"tags":[],"updatedAt":"2026-05-11T10:39:30+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-11 12:00:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8831920","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8831920","identity":"rs-8831920","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}