Objective To investigate the effect of postoperative reduction quality in femoral neck fracture internal fixation on mechanical properties of the femoral head from the perspective of trabecular bone biomechanics.Methods From patients who underwent hip replacement surgery for femoral neck fractures,a total of 26 femoral head slice specimens were obtained.The central axis of the primary compressive trabeculae was defined as the 0° group,with the intersection point of the primary compressive trabeculae and the femoral calcar serving as the center.By rotating the specimens to simulate different reduction angles,the cut femoral head slice specimens were randomly divided into five groups:-10°,-5°,0°,5°,and 10°,representing femoral heads with varying reduction qualities.The specimens were subjected to single compression load tests and fatigue load tests.The load was set from 70 N to 1 400 N,at a frequency of 1 Hz,with 10 000 cycles.Axial stiffness,displacement,and the number of collapse cycles were measured,to compare the biomechanical properties of femoral head specimens under different reduction qualities.Results There were differences in the axial stiffness,displacement,and number of collapse cycles among the femoral head specimens in different groups.Under 800 N load,the axial stiffness of 0° group was significantly greater than that of±10° groups(P＜0.05).The axial stiffness of 0° group was also greater than that of the±5° groups,but the differences were not statistically significant(P＞0.05).The axial stiffness of±5° groups was greater than that of±10° groups(P＜0.05).0° group had a lower displacement than±5° groups and±10° groups.However,the differences in displacement between 0° group and±5° groups were not statistically significant(P＞0.05),while the differences between the 0° group and±10° groups were statistically significant(P＜0.05).The differences in displacement between±5° groups and±10° groups were also statistically significant(P＜0.05).0° group had a significantly higher number of collapse cycles than±10° groups(P＜0.05).The number of collapse cycles in 0° group was also higher than that in±5° groups,but the differences were not statistically significant(P＞0.05).The number of collapse cycles in±5° groups was significantly higher than that±10° groups(P＜0.05).Conclusions The quality of reduction after internal fixation of femoral neck fractures significantly affects the biomechanical properties of the femoral head.This study provides a scientific basis for optimizing treatment and postoperative management,aiming to improve clinical outcomes and patients' quality of life.

Objective:To evaluate the clinical effect of derotational distal femoral osteotomy (DDFO) combined with medial patellofemoral ligament (MPFL) reconstruction assisted by digital orthopedic technique in the treatment of recurrent patellar dislocation with enlarged femoral anteversion angle (FAA).Methods:TThe clinical data of 18 patients (4 men and 14 women; mean age 22.1±0.7 years; range, 18-26 years) with recurrent patellar dislocation (FAA≥30°) admitted to Digital Orthopedic Technology Clinical Application Center in Tianjin hospital from May 2022 to December 2023 were retrospectively analyzed. The average number of patella dislocations were 3.6±0.4 (range, 2-8 times), with a mean symptom duration of 4.3±0.4 years (range, 2-7 years). According to Dejour classification of femoral trochlea dysplasia, there were 5 cases of type A, 3 cases of type B, 6 cases of type C and 4 cases of type D. All patients underwent 3D CT scanning and digital modeling before operation. Based on the modeling results, personalized osteotomy and orthopedic integration guide were designed and printed to direct intraoperative DDFO and MPFL reconstruction. Radiological parameters, knee function and complications were assessed during follow-up. Knee function assessments included visual analogue scale (VAS), Intemational Knee Documentation Committee Knee Form (IKDC), Kujala, Lysholm and Tegner score. The radiological parameters included FAA, patellar tilt angle (PTA), tibial tuberosity-trochlear groove distance (TT-TG) and caton-deschamps index (CDI).Results:All patients underwent surgery and were followed up for 15.4±2.8 months (range, 12-20 months). Complications occurred in 3 patients, including deep venous thrombosis in 2 cases and wound effusion in 1 case. No other complications such as wound infection, nerve injury, vascular injury, fracture nonunion or patella dislocation were recorded. The VAS score improved from 5.4±0.3 preoperatively to 2.1±0.2 at one year postoperatively. The IKDC score improved from 44.4±2.7 to 79.2±1.9 points. The Kujala score improved from 51.8±2.6 to 86.1±1.6, the Lysholm from 49.8±2.5 to 84.9±1.5, and the Tegner score from 2.2±0.2 to 4.1±0.2. The FAA decreased from 39.7°±1.2° to 14.9°±0.2°, the PTA from 33.1°±2.6° to 12.6°±1.4°, and the TT-TG from 20.2±0.6 to 13.9±0.4 mm. The differences between time of all the above-mentioned parameters were statistically significant ( P<0.05). The CDI remained stable, which changed from 1.03±0.02 preoperatively to 1.07±0.01 one year after operation ( P>0.05). Conclusions:After the application of DDFO combined with MPFL reconstruction assist by personalized osteotomy and orthopedic integrated guide, the patient's knee function and imaging parameters were significantly improved at one-year follow-up. In the treatment of recurrent patellar dislocation with enlarged FAA, good early clinical efficacy could be achieved with this operation.

Objective:To evaluate the clinical effect of derotational distal femoral osteotomy (DDFO) combined with medial patellofemoral ligament (MPFL) reconstruction assisted by digital orthopedic technique in the treatment of recurrent patellar dislocation with enlarged femoral anteversion angle (FAA).Methods:TThe clinical data of 18 patients (4 men and 14 women; mean age 22.1±0.7 years; range, 18-26 years) with recurrent patellar dislocation (FAA≥30°) admitted to Digital Orthopedic Technology Clinical Application Center in Tianjin hospital from May 2022 to December 2023 were retrospectively analyzed. The average number of patella dislocations were 3.6±0.4 (range, 2-8 times), with a mean symptom duration of 4.3±0.4 years (range, 2-7 years). According to Dejour classification of femoral trochlea dysplasia, there were 5 cases of type A, 3 cases of type B, 6 cases of type C and 4 cases of type D. All patients underwent 3D CT scanning and digital modeling before operation. Based on the modeling results, personalized osteotomy and orthopedic integration guide were designed and printed to direct intraoperative DDFO and MPFL reconstruction. Radiological parameters, knee function and complications were assessed during follow-up. Knee function assessments included visual analogue scale (VAS), Intemational Knee Documentation Committee Knee Form (IKDC), Kujala, Lysholm and Tegner score. The radiological parameters included FAA, patellar tilt angle (PTA), tibial tuberosity-trochlear groove distance (TT-TG) and caton-deschamps index (CDI).Results:All patients underwent surgery and were followed up for 15.4±2.8 months (range, 12-20 months). Complications occurred in 3 patients, including deep venous thrombosis in 2 cases and wound effusion in 1 case. No other complications such as wound infection, nerve injury, vascular injury, fracture nonunion or patella dislocation were recorded. The VAS score improved from 5.4±0.3 preoperatively to 2.1±0.2 at one year postoperatively. The IKDC score improved from 44.4±2.7 to 79.2±1.9 points. The Kujala score improved from 51.8±2.6 to 86.1±1.6, the Lysholm from 49.8±2.5 to 84.9±1.5, and the Tegner score from 2.2±0.2 to 4.1±0.2. The FAA decreased from 39.7°±1.2° to 14.9°±0.2°, the PTA from 33.1°±2.6° to 12.6°±1.4°, and the TT-TG from 20.2±0.6 to 13.9±0.4 mm. The differences between time of all the above-mentioned parameters were statistically significant ( P<0.05). The CDI remained stable, which changed from 1.03±0.02 preoperatively to 1.07±0.01 one year after operation ( P>0.05). Conclusions:After the application of DDFO combined with MPFL reconstruction assist by personalized osteotomy and orthopedic integrated guide, the patient's knee function and imaging parameters were significantly improved at one-year follow-up. In the treatment of recurrent patellar dislocation with enlarged FAA, good early clinical efficacy could be achieved with this operation.

Objective:To evaluate the clinical effectiveness of high tibial osteotomy (HTO) assisted by digital orthopedic techniques in the treatment of varus knee osteoarthritis secondary to tibial fracture malunion.Methods:The clinical data were retrospectively analyzed of the 16 patients who had been admitted to Clinical Application Center of Digital Orthopedic Technology, Tianjin Hospital for varus knee osteoarthritis secondary to tibial fracture malunion from April 2022 to October 2023. There were 6 men and 10 women, with an age of (56.3±1.6) years and a mean body mass index of (23.8±0.9) kg/m 2. HTO was performed for all the patients using patient-specific instrumentation integrated osteotomy and orthopedic guide which was designed and printed with digital orthopedic techniques. If preoperative imaging indicated symptomatic meniscus injury (tear), intraarticular free body, or intercondylar fossa stenosis in a patient, arthroscopic clearance was first conducted before subsequent performance of HTO at one stage. Clinical effectiveness was evaluated by measuring and comparing hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), posterior tibial slope (PTS), lower limb weight-bearing line (WBL) ratio, Western Ontario and McMaster University (WOMAC) osteoarthritis index, visual analogue scale (VAS) pain score and knee range of motion (ROM) before surgery and 12 months after surgery. Results:The operative time was (41.3±2.1) min and intraoperative fluoroscopy was performed only once in all the patients. All the wounds healed by the first stage with no such complications as hinge point fracture, wound infection, vascular injury, nerve injury, delayed union or nonunion of fracture, lower limb deep venous thrombosis, loosening of internal fixation, or plate rupture. The follow-up time for the 16 patients was (16.3±0.7) months. At 12 months after surgery, the HKA (179.5°±0.5°), MPTA (91.7°±0.5°), WBL ratio (61.2%±0.4%), WOMAC osteoarthritis index [(12.8±0.8) points], VAS pain score [(1.8±0.3) points] and knee ROM (121.8°±1.8°) were significantly better than those before surgery [166.6°±1.3°, 81.8°±0.4°, 29.6%±1.0%, (38.4±2.1) points, (4.8±0.3) points, and 110.5°±2.1°] ( P < 0.05). There was no significant difference in PTS between pre-surgery and 12 months after surgery ( P > 0.05). Conclusions:When HTO is used to treat varus knee osteoarthritis secondary to tibial fracture malunion, assistance of digital orthopedic techniques can improve HKA, MPTA, lower limb alignment, and knee ROM to reduce and recover knee function for the patients.

Objective To investigate the effect of postoperative reduction quality in femoral neck fracture internal fixation on mechanical properties of the femoral head from the perspective of trabecular bone biomechanics.Methods From patients who underwent hip replacement surgery for femoral neck fractures,a total of 26 femoral head slice specimens were obtained.The central axis of the primary compressive trabeculae was defined as the 0° group,with the intersection point of the primary compressive trabeculae and the femoral calcar serving as the center.By rotating the specimens to simulate different reduction angles,the cut femoral head slice specimens were randomly divided into five groups:-10°,-5°,0°,5°,and 10°,representing femoral heads with varying reduction qualities.The specimens were subjected to single compression load tests and fatigue load tests.The load was set from 70 N to 1 400 N,at a frequency of 1 Hz,with 10 000 cycles.Axial stiffness,displacement,and the number of collapse cycles were measured,to compare the biomechanical properties of femoral head specimens under different reduction qualities.Results There were differences in the axial stiffness,displacement,and number of collapse cycles among the femoral head specimens in different groups.Under 800 N load,the axial stiffness of 0° group was significantly greater than that of±10° groups(P＜0.05).The axial stiffness of 0° group was also greater than that of the±5° groups,but the differences were not statistically significant(P＞0.05).The axial stiffness of±5° groups was greater than that of±10° groups(P＜0.05).0° group had a lower displacement than±5° groups and±10° groups.However,the differences in displacement between 0° group and±5° groups were not statistically significant(P＞0.05),while the differences between the 0° group and±10° groups were statistically significant(P＜0.05).The differences in displacement between±5° groups and±10° groups were also statistically significant(P＜0.05).0° group had a significantly higher number of collapse cycles than±10° groups(P＜0.05).The number of collapse cycles in 0° group was also higher than that in±5° groups,but the differences were not statistically significant(P＞0.05).The number of collapse cycles in±5° groups was significantly higher than that±10° groups(P＜0.05).Conclusions The quality of reduction after internal fixation of femoral neck fractures significantly affects the biomechanical properties of the femoral head.This study provides a scientific basis for optimizing treatment and postoperative management,aiming to improve clinical outcomes and patients' quality of life.

Objective:To evaluate the clinical effectiveness of high tibial osteotomy (HTO) assisted by digital orthopedic techniques in the treatment of varus knee osteoarthritis secondary to tibial fracture malunion.Methods:The clinical data were retrospectively analyzed of the 16 patients who had been admitted to Clinical Application Center of Digital Orthopedic Technology, Tianjin Hospital for varus knee osteoarthritis secondary to tibial fracture malunion from April 2022 to October 2023. There were 6 men and 10 women, with an age of (56.3±1.6) years and a mean body mass index of (23.8±0.9) kg/m 2. HTO was performed for all the patients using patient-specific instrumentation integrated osteotomy and orthopedic guide which was designed and printed with digital orthopedic techniques. If preoperative imaging indicated symptomatic meniscus injury (tear), intraarticular free body, or intercondylar fossa stenosis in a patient, arthroscopic clearance was first conducted before subsequent performance of HTO at one stage. Clinical effectiveness was evaluated by measuring and comparing hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), posterior tibial slope (PTS), lower limb weight-bearing line (WBL) ratio, Western Ontario and McMaster University (WOMAC) osteoarthritis index, visual analogue scale (VAS) pain score and knee range of motion (ROM) before surgery and 12 months after surgery. Results:The operative time was (41.3±2.1) min and intraoperative fluoroscopy was performed only once in all the patients. All the wounds healed by the first stage with no such complications as hinge point fracture, wound infection, vascular injury, nerve injury, delayed union or nonunion of fracture, lower limb deep venous thrombosis, loosening of internal fixation, or plate rupture. The follow-up time for the 16 patients was (16.3±0.7) months. At 12 months after surgery, the HKA (179.5°±0.5°), MPTA (91.7°±0.5°), WBL ratio (61.2%±0.4%), WOMAC osteoarthritis index [(12.8±0.8) points], VAS pain score [(1.8±0.3) points] and knee ROM (121.8°±1.8°) were significantly better than those before surgery [166.6°±1.3°, 81.8°±0.4°, 29.6%±1.0%, (38.4±2.1) points, (4.8±0.3) points, and 110.5°±2.1°] ( P < 0.05). There was no significant difference in PTS between pre-surgery and 12 months after surgery ( P > 0.05). Conclusions:When HTO is used to treat varus knee osteoarthritis secondary to tibial fracture malunion, assistance of digital orthopedic techniques can improve HKA, MPTA, lower limb alignment, and knee ROM to reduce and recover knee function for the patients.

This study aims to investigate the function of lmo2363 gene in stress resistance of Liste-ria monocytogenes strain LM83-1.In this study,the lmo2363 gene deletion strain and complement-ation strain of Listeria monocytogenes were constructed using overlapping extended PCR and ho-mologous recombination techniques,and the growth ability,stress survival rate and biofilm forma-tion ability of wild,deletion strain and complementation strain were compared under different stress environments.lmo2363 gene deletion strain and complementation strain of Listeria monocy-togenes were successfully constructed in this experiment.The growth curves showed that the growth capacity of the deletion strain was weaker than the wild strain LM83-1 under 4 ℃,7％NaCl,10％NaCl,3.5％ethanol,4.0％ethanol and pH5 stress(P＜0.001).The results of stress survival test showed that the survival rate of the deletion strain was significantly lower than the wild strain after 1 h treatment with pH3 and 10 mmol/L H2 O2 stress(P＜0.010).The biofilm forming ability of the deletion strain was decreased compared with that of the wild strain(P＜0.050).This study confirmed that lmo2363 gene mediated the adaptation of LM to low temperature,high osmotic pressure,ethanol and acid stress environment and affected the formation of LM bio-film.This study laid a foundation for further exploring the function of lmo2363 gene in the stress resistance process of Listeria monocytogenes.

Shape memory materials are intelligent materials that have the effect of remembering and recovering their original shape in response to external stimuli. The preparation methods include heat treatment and laser sintering for alloy-based memory materials, and thermoplastic methods for polymer-based and composite shape memory materials. Shape memory materials have shown great application value in the field of orthopaedics, such as fracture treatment, bone tissue engineering repair, spinal correction and joint replacement. Shape memory materials have excellent biomechanical properties, providing sustained and effective compression, support and torsion resistance during fracture treatment, as well as the advantage of reducing stress masking in internal fixation of fractures. The sustained stress exerted on the surrounding bone tissue due to environmental changes provides continuous corrective force for spinal deformity correction, and improves the durability of prostheses in arthroplasty. Shape memory materials exhibit good biocompatibility and the performance of inducing cell proliferation, making them suitable for fabricating self-adapting" scaffolds for tissue engineering. When precisely filling bone defect sites, they apply mechanical forces to the autogenous bone, stimulate the proliferation and differentiation of osteoblasts, guide bone regeneration and accelerate bone repair. Moreover, shape memory materials can be used as carriers for drug delivery and release, controlling drug release by adjusting temperature, stress and environmental factors to achieve targeted therapy. With the development of 4D printing technology, shape memory materials have extensive potential in the fields of personalized orthopaedic diagnosis and treatment as well as individualized medical device customization.

Objective:To propose a method to measure the femoral anteversion angle based on the three-dimensional model of femur.Methods:From January 2019 to December 2023, a total of 50 patients (100 femurs) with patellar instability who underwent full-length CT examination of both lower limbs in Tianjin Hospital were retrospectively analyzed, including 16 males and 34 females, aged 28.5±11.9 years (range, 16-57 years). All patients underwent CT examination of both lower limbs, and the imaging data were imported into Mimics 21.0 software as DICOM format files. The femur was extracted by the threshold segmentation function, and the 3D model of the femur was reconstructed by appropriate trimming and smoothing. Three-dimensional models of the femur from 30 patients (60 femurs) were selected and imported into 3-matic 13.0 software for labeling of anatomical points and drawing of axes. The angle between the axis of the distal femur and the axis of the proximal femur was the femoral anteversion angle. Two observers positioned the spatial coordinates of the intercondylar fossa apex, the greater trochanter apex, the center of the femoral head, the femoral through-condylar axis and the posterior condylar tangent marker points on a 3D model of the femur to compare the differences between the groups. The femoral anteversion angles measured by different three-dimensional measurement methods were compared with the clinically reported femoral anteversion angles.Results:The difference between the femoral head center and intercondylar fossa apex coordinate data of 30 patients (60 femurs) measured by the two observers was not statistically significant ( P>0.05), whereas the data for the Y-axis coordinate of the greater trochanter apex were 25.77±23.21 and 22.08±25.73, respectively, and the difference was statistically significant ( t=2.906, P=0.017). The difference between the data of femoral through condylar and posterior condylar tangential coordinates of 30 patients (60 femurs) measured by the two observers was not statistically significant ( P>0.05). Using the femoral mechanical axis as the projection direction, the angle between the transcondylar axis and the posterior condylar tangent line was 5.97°±2.02° (range, 1.48°-12.08°). The anterior tilt of the femur measured by the two observers in the femoral neck cylinder fitting method was 23.35°±7.45° and 24.94°±9.01°, respectively, and the difference was statistically significant ( t=-2.147, P=0.040). The anterior inclination of the femur measured by the two observers in the femoral head ball enlargement method was 24.63°±7.66° and 25.12°±8.84°, the difference was not statistically significant ( t=-0.820, P=0.419). Using the femoral head ball expansion method to locate the proximal femoral axis, two observers measured the anterior tilt angle of the femur in 50 patients (100 femurs) according to the method described above, which was 23.30°±9.41° and 23.57°±9.97°, respectively, without a statistically significant difference ( t=-0.664, P=0.508), both smaller than the 29.56°±8.74° measured based on two-dimensional images in the imaging report, and the difference was statistically significant ( P<0.05). Conclusion:The femoral anteversion angle measured by the angle between the axis of the femoral condyle and the axis of the femoral neck based on the three-dimensional model is accurate and effective, and the measured value is smaller than that based on the two-dimensional images in clinical practice.

Objective:To explore the optimal index of rotational displacement of femoral neck fractures by modeling the axial rotational displacement of femoral neck fractures after reduction and based on X-ray projections.Methods:Six dry human femur specimens, comprising 2 males and 4 females, were utilized in the study. Design and manufacture a proximal femur ortholateral and oblique X-ray casting jigs and mounts. The femoral neck fracture was modeled on the femoral specimen, with Pauwells 30°, 50°, and 70° models (2 each) made according to Pauwells typing. The fractures were manually repositioned with residual anterior 20°, 40° and 60° axial rotational displacements. Each fracture model was projected at different angles (pedicled 40°, pedicled 20°, vertical 0°, cephalad 20°, and cephalad 40°), and the trabecular angle and Garden's alignment index of the model were measured to observe the imaging characteristics of the fracture line on the medial oblique and lateral oblique radiographs.Results:In the presence of a 20° and 40° anterior rotational displacement following reduction of a femoral neck fracture, the trabecular angle in the rotationally displaced group was not significantly different from that of the anatomically repositioned group in various projection positions. However, when a residual rotational displacement of 60° was present, the trabeculae appeared blurred at most projection angles in the Pauwells 30° and 50° models, failing to measure trabecular angles. In the Pauwells 70° fracture model, the trabecular angle in the rotational displacement group was significantly different from that in the anatomical reduction group. In anteroposterior radiographs, when the anterior rotation displacement was 60° in the Pauwells 70° group, Garden's contralateral index showed an unsatisfactory restoration (150°, 142°), whereas all rotationally displaced models in the Pauwells 30° and Pauwells 50° groups had a Garden's contralateral index of >155°, which achieved an acceptable restoration. In lateral radiographs, all rotational displacement models with Garden's alignment index>180° failed to achieve acceptable repositioning, and the larger the Pauwells angle the greater the Garden's alignment index at the same rotational displacement. In the internal oblique position with a bias towards the foot side, the image showed partial overlap between the femoral head and the shaft, making it difficult to assess the quality of the reduction. Conversely, when projected cephalad, the femoral neck appeared longer, particularly at a projection angle of 40° cephalad, allowing for clear observation of the fracture line and the anatomy of the proximal femur. The trabeculae were not well visualized in the external oblique position.Conclusion:There are limitations in applying the trabecular angle to assess the axial rotational displacement of the femoral head after reduction of femoral neck fractures. The Pauwells 70° with residual rotational anterior displacement of 60° was the only way to detect axial rotational displacement of the femoral head on anteroposterior radiographs Garden's alignment index. For the determination of axial rotational displacement of the femoral head, the Garden's alignment index on lateral radiographs provides higher reliability.