BACKGROUND:Conventional surgical repair can cause large traumas in patients with knee injuries, and patients often recover slowly after implant fixation, most of whom can appear to have poor recovery of knee function. OBJECTIVE: To explore the folow-up effect of arthroscopic double-steel wire clip fixation on tibial eminence avulsion fracture of anterior cruciate ligament. METHODS: A retrospective analysis was performed on the clinical data of 23 patients with tibial eminence avulsion fractures, who were given arthroscopic double-steel wire clip fixation. The patients were folowed up for 1-6 months. Short- and middle-term therapeutic effect as wel as IKDC and Lysholm scores before and after treatment were observed and analyzed. RESULTS AND CONCLUSION:The operation time was 35-65 minutes, and no complications, such as blood, nerve and anterior cruciate ligament injuries occurred. Moreover, no infection and other poor biocompatible reactions occurred after internation fixation. Al patients were folowed up for 1-6 months. The excelent and good rate was 87% at 1 month after treatment and 96% at 6 months after treatment. Al the patients had improved IKDC score and Lysholm score after treatment (P < 0.05), indicating that the knee function of patients was improved significantly.

Objective To evaluate the clinical efficacy of arthroscopic treatment of tibial intercondylar eminence avulsion fracture in pediatric patients without epiphyseal interference.Methods From February 2010 to February 2014,18 children patients with avulsion fracture of tibial eminence were admitted.They were 12 boys and 6 girls,from 7 to 14 years of age (average,10.4 years).Four cases were complicated with meniscus injury and 2 with medial collateral ligament injury.The mean time from injury to surgery was 4.5 days (range,from 2 to 7 days).According to Meyers-McKeever classification,13 children were type Ⅱ and 5 type Ⅲ.They were treated with Ultrabraid sutures arthroscopically.After reposition,the bone fragments were fixated to the distal epiphysis of tibial tubercle through the inferior of transverse ligament of knee to avoid epiphyseal injury.Anterior drawer test,Lanchman test,pivot shift test and Lysholm knee scoring were conducted at all clinical follow-up visits to assess functional recovery.Results All children were followed up from 10 to 24 months (average,15 months).The X-ray examination demonstrated bone union in all cases.At the end of follow-up,all children achieved satisfactory recovery of range of motion without complications like joint stiffness,joint relaxation,dysfunction or epiphyseal injury.The anterior drawer test,Lanchman test and pivot shift test were all negative at the last follow-up.The mean Lysholm knee scores improved significantly from preoperative 45.6 ± 7.4 to 92.4 ± 5.8 at the final follow-up (t =-25.403,P ＜ 0.01).Conclusions Bone reposition under arthroscopy with suture fixation is reliable and minimally invasive in the treatment of avulsion fractures of tibial intercondylar eminence in pediatric patients.

Objective To compare the biomechanical characteristics between S2 alar-iliac (S2AI) screw and sacroiliac joint screw in treating unilateral type C sacroiliac joint dislocation. Methods A 25 year-old healthy male adult agreed to take computed tomography scan of the pelvis. The pelvic floor thickness was 1 mm and the image data were saved in DCOM format. A three dimensional finite element model of intact pelvis was reconstructed by Mimics, Geomagic, SolidWorks, and Abaqus softwares. A finite element model of type C unilateral sacroiliac dislocation was established. One S1 vertebral sacroiliac screw of 6.5 mm in diameter (S1 group), one S2AI screw (S2AI group) and one Si vertebra sacroiliac screw + one S2 vertebra sacroiliac screw (S1+S2 group) were placed in the model, respectively. The500 N vertical load on the upper surface of the sacrum was simulated. The displacement value of sacroiliac joint, the displacement of sacrum, the stress value of the internal fixation and surrounding bone, and the stress distribution cloud map were recorded and analyzed. Results The displacement data showed that displacement distribution in the three groups had a consistent trend. In terms of the absolute value of displacement the result was S, group＞S 2AI group＞S1+ S2 group, of which the maximum displacement of sacroiliac joint in S1 groups was 0.87 mm and that of sacrum was 1.6 mm; the maximum displacement of sacroiliac joint in S2 AI group was 0.22 mm, and that of sacrum was 0.24 mm; the maximum displacement of the sacroiliac joint in S1 + S2 group was 0.06 mm, and that of sacrum was0.16 mm. Stress data showed that the stress in the internal fixation was mainly distributed at the sacroiliac joint, and the stress result was S2AI group＞S, group＞S, + S2 group, of which the maximum stress value was 52.8 MPa in S1 group, 62.1 MPa in S2AI group, and 38.2 MPa in S1 + S2 group. The stress around the screws was also concentrated at the sacroiliac joint, and the stress result was S1 group＞S2AI group＞S1 + S2 group, of which the maximum stress value was 56.8 MPa in S1 group, 11.2 MPa in S2AI group, and 5.8 MPa in S1 + S2 group. Conclusions Single S1 screw, single S2 AI screw and S, screws combined S2 screws can be used for the treatment of unilateral C type sacroiliac joint dislocation. Early weight bearing of single S1 screw might lead to the risks of increased sacroiliac joint displacement and internal fixation failure. S2 AI screw fixation and S1 + S2 screw fixation have similar biomechanical strength, allowing early weight-bearing and contributing to better postoperative rehabilitation.

Objective:Comparison of biomechanical stability of S 2-alar-iliac screw and S 1 pedicle screw fixation (S 2AI-S 1) with conventional sacroiliac screw in the treatment of Denis type II sacral fractures by finite element analysis. Methods:The lumbar spine and pelvis of a male volunteer with normal skeletal structure were scanned by CT, followed by three-dimensional reconstruction. The finite element model of right Denis type II sacral fracture and pubic symphysis injury was constructed using ANSYS 17.0 software. The anterior pelvic ring is fixed with a five-hole steel plate, and the posterior pelvic ring is fixed with four different internal fixation methods, namely, sacroiliac screw (S 1 segment half-thread hollow screw), S 2AI-S 1 and S 2AI screw and contralateral S 1 screw fixation (S 2AI-CS 1). By restraining the bilateral acetabular and applying 500 N vertical stress above the L 4 vertebral body, the maximum displacement, maximum von Mises stress and vertical stiffness of the three groups of internal fixation were compared. Results:In terms of the maximum displacement of the sacrum in the vertical and anteroposterior directions, the S 2AI-S 1 model was the smallest (1.40 mm, 1.40 mm, respectively), while the S 2AI-CS 1 model was the largest (1.60 mm, 1.56 mm, respectively); In terms of the maximum displacement of the sacrum in the horizontal direction, the S 2AI-S 1 model is the smallest (0.19 mm), while the SIS model is the largest (0.37 mm); In terms of the maximum von Mises stress of internal fixation, the stress of the sacroiliac screw model is the largest (216.02 MPa), while the stress of the S 2AI-S 1 model is the smallest (39.82 MPa); In terms of the maximum von Mises stress of the bone around the screw, the stress of the sacroiliac screw model (39.68 MPa) is the largest and that of the S 2AI-S 1 model is the smallest (31.56 MPa); In terms of the vertical displacement of the center point of the upper surface of the S 1 vertebral body, the sacroiliac screw, S 2AI-S 1 and S 2AI-CS 1 groups were 0.83 mm, 0.73 mm and 0.93 mm, respectively. Using the vertical displacement of the center point of the upper surface of the S 1 vertebral body to predict the vertical stiffness of the three groups of models, from large to small, are S 2AI-S 1, sacroiliac screw and S 2AI-CS 1. Conclusion:S 2AI-S 1 fixation has good biomechanical stability in three-dimensional finite element analysis. It can be used as a new type of internal fixation for the treatment of sacral fractures and is worthy of promotion.

Unstable sacral fracture is usually caused by high-energy trauma. Unstable sacral fracture often results in damage to the mechano-conductive structures of the spine and pelvis and thereby affects walking dysfunction. Treatment of sacral fracture has been a challenge due to the complex local anatomy, unique biomechanics and poor bone quality of the sacrum. The screw-rod fixation system has always played an important role in the treatment of variant sacral fracture and more severe sacral fracture. With the introduction of new technology, the screw-rod fixation system has evolved into a variety of structural types. According to whether the fixation range extends to the spine, it can be divided into two categories including spine-pelvic stabilization techniques and pelvic stabilization techniques. The authors review the progress of the screw-rod fixation system in the treatment of sacral fracture from aspects of biomechanical properties and clinical efficacy, so as to provide a reference for the selection of clinical internal fixation.

Objective:To explore the efficacy and safety of TiRobot combined with three-dimensional imaging in the minimally invasive surgery for pelvic fractures.Methods:A retrospective analysis was conducted of the 40 patients with pelvic fracture who had been treated by fixation with S1 and S2 sacroiliac screws at Department of Orthopaedics and Traumatology, Yangjiang People's Hospital from January 2019 to May 2021. They were divided into 2 groups according to their treatment methods. In the TiRobot group of 20 cases subjected to percutaneous sacroiliac screw fixation assisted by TiRobot combined with three-dimensional imaging, there were 13 males and 7 females with an age of (38.2 ± 8.8) years. In the manual group of 20 cases subjected to fixation with manual placement of sacroiliac screws under conventional C-arm fluoroscopy, there were 11 males and 9 females with an age of (37.3 ± 9.2) years. The 2 groups were compared in terms of fluoroscopy time for screw placement, guide needle adjustment, operation time, intraoperative blood loss, visual analogue scale (VAS) 72 hours after operation, postoperative hospital stay, time to ambulation, excellent to good rate of screw placement, complication rate, fracture union time, Majeed score at 6 months after operation, and excellent to good rate of functional evaluation.Results:There was no significant difference between the 2 groups in their preoperative general data, showing they were comparable ( P > 0.05). In the TiRobot group, fluoroscopy time for screw placement [(8.2 ± 2.9) s], guide needle adjustment [(0.4 ± 0.2) times], operation time [(67.4 ± 5.5) min], and intraoperative blood loss [(36.5 ± 8.0) mL] were significantly less than those in the manual group [(40.4 ± 4.5) s, (8.6 ± 0.7) times, (78.4 ± 7.2) min, and (41.6 ± 7.8) mL], postoperative VAS [3.0 (4.0, 5.0) points] was significantly lower than that in the manual group [4.0 (5.0, 6.0) points], the excellent to good rate of screw placement (100%, 40/40) was significantly higher than that in the manual group (85.0%, 34/40), and the complication rate (5.0%,1/20) was significantly lower than that in the manual group (35.0%, 7/20) (all P < 0.05). There was no significant difference between the 2 groups in postoperative hospital stay, time to ambulation, fracture union time, Majeed score, or excellent to good rate of functional evaluation ( P > 0.05). Conclusion:In the minimally invasive surgery for pelvic fractures, TiRobot combined with three-dimensional imaging leads to positive outcomes, because it can reduce operation time and radiation exposure, improve accuracy of screw placement, and increase safety.