BACKGROUND:Currently,research both domestically and internationally on patellofemoral pain syndrome has explored the kinematics and dynamics during daily activities such as stair ascent and descent,and walking. However,there is a lack of studies examining the lower limb biomechanical characteristics of young female patients with patellofemoral pain syndrome in different squatting conditions.OBJECTIVE:To investigate the lower limb biomechanical characteristics among young female patients with patellofemoral pain syndrome in different functional states of the subtalar joint,providing theoretical support for the clinical treatment of various types of patellofemoral pain syndrome.METHODS:A total of 33 participants were included in this study. There were 10 subjects in the healthy control group (group C). The other 27 subjects with patellofemoral pain syndrome were divided into two groups according to the foot posture index:14 subjects in the normal subtalar joint group (group A,foot posture index 0-6 points) and 13 subjects in the abnormal subtalar joint group (group B,foot posture index 7-12 points). The biomechanical indices of thesubjects in each group were collected and compared when they walked on stairs at normal speed. The kinematic indices included the three-dimensional joint angles of the hip and knee and the sagittal plane joint angles of the ankle at the initial contact moment and the moment of maximum knee flexion angle during the stance period. The dynamic indices included the three-dimensional joint torques of the hip and knee and the sagittal plane joint torques of the ankle at the moment of maximum knee flexion angle during the stance period. The surface electromyography indices included the root mean square amplitudes of the vastus medialis,vastus lateralis,rectus femoris,semitendinosus and semimembranosus,biceps femoris,and gluteus medius in the pre-activation stage and the buffering stage.RESULTS AND CONCLUSION:(1) At the initial ground contact moment,group A exhibited a greater knee flexion angle (P<0.05),greater hip external rotation angle (P<0.01),and smaller knee external rotation angle (P<0.01) compared to group B. Compared to group C,group A showed a greater knee flexion angle and smaller hip flexion angle (both P<0.01). Group B demonstrated a greater knee external rotation angle and smaller hip external rotation angle and hip flexion angle (all P<0.01) compared to group C. (2) At the moment of maximum knee flexion,group A had a smaller knee valgus angle (P<0.05),smaller knee external rotation angle (P<0.05),and greater knee flexion angle (P<0.01) compared to group B. Compared to group C,group A showed a smaller knee valgus angle (P<0.05),smaller hip flexion angle (P<0.01),and smaller hip external rotation angle (P<0.05). Group B had a smaller knee flexion angle,hip flexion angle,hip external rotation angle,and greater knee external rotation angle (all P<0.01) compared to group C. Additionally,group A exhibited a greater hip internal rotation moment (P<0.05) and plantarflexion moment (P<0.01) compared to group C. (3) At normal speed during the staircase buffering phase,group C showed higher activation levels than group A in the vastus lateralis (P<0.05),vastus medialis (P<0.01),gluteus medius (P<0.01),and biceps femoris (P<0.05). Group C also had higher activation levels than group B in the vastus medialis (P<0.01),gluteus medius (P<0.01),and biceps femoris (P<0.05). Additionally,group A showed higher activation in the semitendinosus and semimembranosus muscles compared to group B (P<0.05). (4) These findings indicate that young female patients with patellofemoral pain syndrome have stiffer hip and knee joint buffering while descending stairs,potentially compensated by the ankle joint. Low muscle activation levels contribute to patellofemoral pain,with those having normal subtalar joints but experiencing pain showing the lowest and most abnormal activation. ③ Abnormal biomechanics in the normal subtalar joint group are mainly due to insufficient hip and knee flexion. Abnormal biomechanics in the abnormal subtalar joint group are mainly due to excessive subtalar joint pronation.

Background Accurate T-staging is critical for esophageal cancer therapy,but CT-based assessment has significant limitations.Large vision models(LVMs)hold promise,yet their zero-shot clinical diagnostic capability without fine-tuning remains unvalidated.Methods A retrospective analysis was conducted on the chest CT images from 98 esophageal cancer patients and 50 normal controls.Using radiologist-consensus as the gold standard,the zero-shot T-staging performance of 3 LVMs(GPT-5,Gemini,and MedGemma)was evaluated with prompts of varying complexity.Results GPT-5 exhibited the highest accuracy and stability.Significant biases were observed among models:Gemini tended to over-stage,while MedGemma showed a tendency to under-stage.All models faced challenges in identifying early-stage tumors,but structured prompts improved diagnostic performance for mid-to-late stage lesions.Conclusion LVMs have potential for zero-shot T-staging,but their performance highly depends on model choice and prompt design.The generic model GPT-5 show superior zero-shot generalization.However,current model performance is not yet clinically viable,especially for early diagnosis.Future work should focus on fine-tuning with high-quality clinical data and developing standardized prompt frameworks.

Background Accurate T-staging is critical for esophageal cancer therapy,but CT-based assessment has significant limitations.Large vision models(LVMs)hold promise,yet their zero-shot clinical diagnostic capability without fine-tuning remains unvalidated.Methods A retrospective analysis was conducted on the chest CT images from 98 esophageal cancer patients and 50 normal controls.Using radiologist-consensus as the gold standard,the zero-shot T-staging performance of 3 LVMs(GPT-5,Gemini,and MedGemma)was evaluated with prompts of varying complexity.Results GPT-5 exhibited the highest accuracy and stability.Significant biases were observed among models:Gemini tended to over-stage,while MedGemma showed a tendency to under-stage.All models faced challenges in identifying early-stage tumors,but structured prompts improved diagnostic performance for mid-to-late stage lesions.Conclusion LVMs have potential for zero-shot T-staging,but their performance highly depends on model choice and prompt design.The generic model GPT-5 show superior zero-shot generalization.However,current model performance is not yet clinically viable,especially for early diagnosis.Future work should focus on fine-tuning with high-quality clinical data and developing standardized prompt frameworks.

BACKGROUND:Currently,research both domestically and internationally on patellofemoral pain syndrome has explored the kinematics and dynamics during daily activities such as stair ascent and descent,and walking. However,there is a lack of studies examining the lower limb biomechanical characteristics of young female patients with patellofemoral pain syndrome in different squatting conditions.OBJECTIVE:To investigate the lower limb biomechanical characteristics among young female patients with patellofemoral pain syndrome in different functional states of the subtalar joint,providing theoretical support for the clinical treatment of various types of patellofemoral pain syndrome.METHODS:A total of 33 participants were included in this study. There were 10 subjects in the healthy control group (group C). The other 27 subjects with patellofemoral pain syndrome were divided into two groups according to the foot posture index:14 subjects in the normal subtalar joint group (group A,foot posture index 0-6 points) and 13 subjects in the abnormal subtalar joint group (group B,foot posture index 7-12 points). The biomechanical indices of thesubjects in each group were collected and compared when they walked on stairs at normal speed. The kinematic indices included the three-dimensional joint angles of the hip and knee and the sagittal plane joint angles of the ankle at the initial contact moment and the moment of maximum knee flexion angle during the stance period. The dynamic indices included the three-dimensional joint torques of the hip and knee and the sagittal plane joint torques of the ankle at the moment of maximum knee flexion angle during the stance period. The surface electromyography indices included the root mean square amplitudes of the vastus medialis,vastus lateralis,rectus femoris,semitendinosus and semimembranosus,biceps femoris,and gluteus medius in the pre-activation stage and the buffering stage.RESULTS AND CONCLUSION:(1) At the initial ground contact moment,group A exhibited a greater knee flexion angle (P<0.05),greater hip external rotation angle (P<0.01),and smaller knee external rotation angle (P<0.01) compared to group B. Compared to group C,group A showed a greater knee flexion angle and smaller hip flexion angle (both P<0.01). Group B demonstrated a greater knee external rotation angle and smaller hip external rotation angle and hip flexion angle (all P<0.01) compared to group C. (2) At the moment of maximum knee flexion,group A had a smaller knee valgus angle (P<0.05),smaller knee external rotation angle (P<0.05),and greater knee flexion angle (P<0.01) compared to group B. Compared to group C,group A showed a smaller knee valgus angle (P<0.05),smaller hip flexion angle (P<0.01),and smaller hip external rotation angle (P<0.05). Group B had a smaller knee flexion angle,hip flexion angle,hip external rotation angle,and greater knee external rotation angle (all P<0.01) compared to group C. Additionally,group A exhibited a greater hip internal rotation moment (P<0.05) and plantarflexion moment (P<0.01) compared to group C. (3) At normal speed during the staircase buffering phase,group C showed higher activation levels than group A in the vastus lateralis (P<0.05),vastus medialis (P<0.01),gluteus medius (P<0.01),and biceps femoris (P<0.05). Group C also had higher activation levels than group B in the vastus medialis (P<0.01),gluteus medius (P<0.01),and biceps femoris (P<0.05). Additionally,group A showed higher activation in the semitendinosus and semimembranosus muscles compared to group B (P<0.05). (4) These findings indicate that young female patients with patellofemoral pain syndrome have stiffer hip and knee joint buffering while descending stairs,potentially compensated by the ankle joint. Low muscle activation levels contribute to patellofemoral pain,with those having normal subtalar joints but experiencing pain showing the lowest and most abnormal activation. ③ Abnormal biomechanics in the normal subtalar joint group are mainly due to insufficient hip and knee flexion. Abnormal biomechanics in the abnormal subtalar joint group are mainly due to excessive subtalar joint pronation.

OBJECTIVE:To systematically review the clinical effect of blood flow restriction training on rehabilitation after anterior cruciate ligament reconstruction to provide a reference for clinical practice. METHODS:Databases including CNKI,WanFang,PubMed,Web of Science and EBSCO were searched to collect randomized controlled trials of blood flow restriction training in the intervention of anterior cruciate ligament reconstruction from inception to August 10,2022.Outcomes included knee muscle strength,knee muscle mass,and knee function evaluation,all of which were continuous variables.Two reviewers independently screened the literature and extracted data.Cochrane bias risk assessment tool and Physiotherapy Evidence Database Scale were used to evaluate the bias risk of the included articles.Meta-analysis was then performed using RevMan 5.4 software. RESULTS:A total of 9 publications were included,including 226 subjects,114 in the trial group and 112 in the control group.Meta-analysis results showed that compared with conventional resistance training,the blood flow restriction training group could significantly improve knee muscle strength[SMD=0.54,95%CI(0.29,0.79),P＜0.01],muscle mass[SMD=0.26,95%CI(0.06,0.46),P=0.01]and knee joint function[SMD=1.17,95%CI(0.53,1.80),P＜0.01].Subgroup analysis showed that only when the intervention time was more than 4 weeks,there were significant improvements in knee joint muscle strength[SMD=0.68,95%CI(0.38,0.97),P＜0.01]and muscle mass[SMD=0.38,95%CI(0.09,0.68),P=0.01]. CONCLUSION:Current evidence shows that blood flow restriction training can improve muscle strength and knee function in patients with anterior cruciate ligament reconstruction and reduce muscle atrophy.It is recommended that the postoperative intervention time should be more than 4 weeks to achieve better muscle strength and muscle mass improvement.

Objective To analyze the differences of von Mises stress distribution in knee cartilage and meniscus in female with generalised joint hypermobility (GJH) and healthy female during drop jump landing. Methods The kinematic and ground reaction force (GRF) characteristics of knee joint in female with GJH and healthy female at the moment of peak vertical GRF (VGRF) during loading phase of drop jump landing were collected. The knee joint reaction force was calculated via inverse dynamics, and the combined force of knee joint along long axis of the femur was applied as the load. Based on three-dimensional (3D) finite element model of a female knee joint, numerical simulations were performed separately during drop jump landing of subjects in two groups, and von Mises stresses and stress distribution of knee cartilage and meniscus were calculated. Results At the moment of peak VGRF during drop jump landing, knee flexion and valgus angles in GJH group and control group showed a statistical significance (P<0. 05). Compared with control group, knee flexion angle decreased and valgus angle increased in GJH group. During drop jump landing, GJH group bore larger stress inside the knee joint, and stress distribution in weight-bearing areas of the medial and lateral tibiofemoral compartments was uneven, while the lateral femoral cartilage lateral condyle, the anterior and middle lateral of lateral tibial cartilage, the anterior angle and body lateral margin of lateral meniscus were stress concentration sites. Conclusions For females with GJH, the stability of knee joint decreases and force lines change in jumping events, due to the increased range of motion of knee joint and relaxation of joint capsule, which increases the risk of cartilage and meniscal injury in lateral knee joint. During jumping sports, females with GJH should especially prevent knee joint injury caused by altered force lines in frontal plane of knee joint.