Objective: This study aimed to compare the biomechanical stability and clinical efficacy of the Kirschner-wire (K-wire) tension band combined with patellar cerclage and an anchor-loop plate (ALP) in treating inferior-pole patellar fracture.Methods: The finite element model was established to analyze the mechanical properties of a K-wire tension band combined with patellar cerclage and ALP fixation in the treatment of inferior patellar pole fracture. The clinical data of 49 patients with patellar inferior-pole fracture (AO/OTA 34 A1) admitted to our hospital from January 2017 to July 2021 were retrospectively analyzed. Among these, 28 cases were fixed with ALPs (ALP group) and 21 cases were fixed with K-wire tension bands combined with patellar cerclage (K-wire group). By reviewing the medical records and follow-up results, we compared the operation time, final knee joint activity, incidence of secondary surgery, postoperative complications, and joint function recovery between the two groups.Results: The biomechanical analysis of the finite element model showed that the maximum displacement of the K-wire group was 1.87 times that of the ALP group. The maximum stress of the K-wire group was 1.34 times that of the ALP group. The maximum stress of the pole bone in the K-wire group was 13.89 times that of the ALP group. The average follow-up times of the K-wire group and ALP group were similar (p > 0.05), and the average ages of the two groups were similar (p > 0.05). The operation time of the ALP group was significantly shorter than that of the K-wire group (p < 0.05).The final knee joint activity of the ALP group was significantly greater than that of the K-wire group (p < 0.05). The Bostman patellar fracture function score of the ALP group was significantly better than that of the K-wire group at 3 and 9 months after operation (p < 0.05). Postoperative complications of the two groups included 1 case (3.6%) in the ALP group with internal fixation-stimulation complications and, in the K-wire group, 3 cases (14.3%) with internal fixation stimulation complications and 1 case (4.8%) with infection.Conclusion: The ALP and K-wire tension band combined with patella cerclage models were tested at 500 N, and no damage occurred, indicating that the newly designed ALP is safe in mechanical structure. The ALP has better therapeutic effect in biomechanical stability, postoperative complications, secondary surgery, and knee function. This technique is an effective method for the treatment of inferior-pole patellar fracture.

Objective This study aimed to compare the distal femoral epiphyseal stress of Leg Length Discrepancy and Pelvic Tilt, to explain the phenomenon of genu varum and genu valgum in children with unequal lower extremities or pelvic tilt. Methods The finite element models was established to analyze the distal femoral epiphyseal Equivalent Von Mises Stress, We reconstructed the right sacrum, pubis, ischium, and femur of a healthy child by finite element method, and generated the distal femoral epiphysis and other cartilage structures. The left femur was amputated (1, 2, 3, 4, 5, 6cm) to study the stress changes in the bilateral distal femoral epiphysis. In addition, we tilted the pelvis of four models and placed the distal femur at the same level to study the stress changes after the pelvis was tilted. Results The Equivalent Von Mises Stress distribution of the distal femoral epiphysis on both sides of the children with unequal lower limbs was uneven, and the stress stimulation on the lateral side was greater than that on the medial side. And when the pelvis is tilted, this stimulation is more obvious. Conclusions We reconstructed a healthy child's pelvis and femur by Finite-Element, including cartilage and epiphyseal structures. The left femur was amputated to simulate the Leg Length Discrepancy, the pelvis tilt was also studied. Both lead to the increased lateral stress, with pelvic tilt having a greater effect.

Purpose To elucidate the biomechanical characteristics of fracture defect filled with spinal cage by finite element analysis, and investigate the clinical efficacy of medial and lateral dual plates with spinal cage for the treatment of hyperextension bicondylar tibial plateau fractures. Methods A 10-mm cuneiform defective osteotomy of proximal tibia was created in the finite element model to simulate hyperextension bicondylar tibial plateau fractures. The defect area in the established model was filled with spinal cage (Group A) or allograft bones (Group B) after fracture reduction. The biomechanical properties of both models were tested under axial compression loading and the maximum displacement of the fragments was recorded. Furthermore, a retrospective analysis was conducted on 12 patients with hyperextension bicondylar tibial plateau fractures who were surgically treated at the Lower Limb Surgery Ward of Traumatic Orthopedic Department, Xi’an Honghui Hospital from January 2020 to January 2022. The gender, age, cause of injury, associated injury, the preoperative and postoperative posterior tibial slope angle (pTSA), duration between injury and operation, surgical duration, intraoperative blood loss, complications, time of bone healing, time of weight bearing, Rasmussen radiological criteria and HSS scores were collected and analyzed. Results The finite element model showed that the maximum displacement in Group A was 0.1006 mm and that in Group B was 0.1203 mm, whereas the maximum stress in the two groups were 39.70 MPa and 43.69 MPa respectively. Therefore, implantation of spinal cage into the bone defect area after fracture reduction has obvious biomechanical advantages. We also analyzed 12 patients (9 males and 3 females, aged ranging from 27 to 66 years with mean age of 46.0 ± 12.3 years) with Schatzker type VI fractures. The patients were successfully followed up for an average of 12.50 ± 3.37 months (8 to 18 months). The postoperative pTSA was significantly improved related to the preoperative pTSA (P < 0.001). The average duration between injury and operation was 6.08 ± 2.78 days, the average surgical duration was 131.67 ± 32.71 min, and the average intraoperative blood loss was 320.83 ± 113.73ml. Furthermore, the average time of bone healing was 13.58 ± 2.57 weeks and the average time of weight-bearing was 8.33 ± 2.93 weeks. In addition, 33.33% of postoperative complications was observed in 1 case of superficial wound infection and dehiscence, 1 case of delayed union combined with limited range of motion of the knee joint and 2 cases of deep vein thrombosis. The excellent and good rates of Rasmussen radiological criteria and HSS scores were 83.33% and 91.67% respectively. Conclusion Fracture reduction and fixation by medial and lateral dual plates and spinal cage is an effective method for the treatment of hyperextension bicondylar tibial plateau fractures, and has biomechanical advantages such as favorable bone healing time, weight bearing time, radiographic and clinical functional outcomes.

ObjectiveThis study aims to find the optimal arrangement of the Kirschner wire (K-wire) in the sagittal plane for fixation of a pediatric lateral condylar humeral fracture (Milch type II) by using finite element analysis (FEA).MethodsA model of lateral condyle fracture in a 6-year-old boy was developed, and an XYZ coordinate system was established based on this model. The YZ plane was defined as the sagittal plane to investigate the impact of the angle formed by the first and second K-wires on stability. Two configurations were studied for each angle: parallel and divergent. Evaluation indicators included the maximum displacement of the fracture fragment and the maximum von Mises stress in the pins and bone.ResultsThe model with a −60° angle showed the best performance in both evaluation indicators. The parallel and divergent pin configurations had different performances in each group. The displacement results for negative angles were similar, and this result was better than those for positive angles.ConclusionWe successfully created a model of pediatric lateral condyle humerus fracture (Milch type II) and performed K-wire fixation with varying sagittal plane configurations, combined with FEA. Our findings demonstrate that the angle of −60° between the two pins in the sagittal plane provided the highest level of stability, with divergent configurations proving superior to parallel pinning at this angle.