[Application of Deep Learning to Diagnose and Classify Adolescent Idiopathic Scoliosis].

A deep learning-based model for automatic diagnosis and classification of adolescent idiopathic scoliosis has been constructed. This model mainly included key points detection and Cobb angle measurement. 748 full-length standing spinal X-ray images were retrospectively collected, of which 602 images were used to train and validate the model, and 146 images were used to test the model performance. The results showed that the model had good diagnostic and classification performance, with an accuracy of 94.5%. Compared with experts' measurement, 94.9% of its Cobb angle measurement results were within the clinically acceptable range. The average absolute difference was 2.1°, and the consistency was also excellent (r2≥0.9552, P<0.001). In the future, this model could be applied clinically to improve doctors' diagnostic efficiency.

[Development and Application of Deep Learning-Based Model for Quality Control of Children Pelvic X-Ray Images].

Objective: A deep learning-based method for evaluating the quality of pediatric pelvic X-ray images is proposed to construct a diagnostic model and verify its clinical feasibility. Methods: Three thousand two hundred and forty-seven children with anteroposteric pelvic radiographs are retrospectively collected and randomly divided into training datasets, validation datasets and test datasets. Artificial intelligence model is conducted to evaluate the reliability of quality control model. Results: The diagnostic accuracy, area under ROC curve, sensitivity and specificity of the model are 99.4%, 0.993, 98.6% and 100.0%, respectively. The 95% consistency limit of the pelvic tilt index of the model is -0.052-0.072. The 95% consistency threshold of pelvic rotation index is -0.088-0.055. Conclusion: This is the first attempt to apply AI algorithm to the quality assessment of children's pelvic radiographs, and has significantly improved the diagnosis and treatment status of DDH in children.

Application of pedobarographic analysis in neglected congenital clubfoot patients following Ponseti treatment for recurrence prediction.

Background: Neglected congenital clubfoot (NCCF) is a birth deformity that remains untreated until the child begins to walk. Irrespective of the treatment protocols employed, children with NCCF face an elevated risk of recurrence following the initial correction. Predicting this recurrence could enable early intervention for high-risk children, ultimately diminishing the likelihood of invasive surgery. Methods: From January 2006 to January 2022, a total of 33 unilateral NCCF patients were enrolled in this study at Xijing Hospital. Pedobarographic tests were performed at three distinct time points: after the initial Ponseti treatment, before recurrence treatment, and after recurrence treatment. Four derivative parameters were developed for predicting recurrence, namely the difference of the contact time% (DCT%), difference of the contact area% (DCA%), difference of the peak pressure (DPP), and difference of the pressure-time integral (DPTI) between the two feet. ROC curves, Kaplan-Meier survival analysis, and Cox regression were employed to identify potential prognostic factors. Results: Out of the 33 unilateral NCCF patients, recurrence occurred in 8 individuals, with an average follow-up period of 109.8 months. The predictive parameter for recurrence is the midfoot (MF) zone's DCT% (MF-DCT%). When the contact time (CT)% of the affected side was 20.69% higher than that of the unaffected side, the hazard ratio (HR) of recurrence increased by 7.404 times. Another predictive plantar pressure parameter is the DPP in the MF zone (MF-DPP). If the PP of the affected side was 159% higher than that of the unaffected side, the HR of recurrence increased by 9.229 times. The MF-DCT% and MF-DPP of recurrence patients were assessed at three time points for comparisons, further validating their predictive ability for recurrence. Conclusion: Although satisfactory clinical outcomes were achieved in patients with unilateral NCCF after the initial Ponseti treatment, the plantar pressure distribution does not return to normal levels, which may indicate future recurrence. DCT% and DPP in the MF zone can be used as plantar pressure predictors of recurrence in patients with NCCF.

A novel approach for screening standard anteroposterior pelvic radiographs in children.

Anteroposterior pelvic radiography is the first-line imaging modality for diagnosing developmental dysplasia of the hip (DDH). Nonstandard radiographs with pelvic malposition make the correct diagnosis of DDH challenging. However, as the only method available for screening standard pelvic radiographs, traditional manual assessment is relatively laborious and potentially erroneous. We retrospectively collected 3,247 pelvic radiographs. There were 2,887 radiographs randomly selected to train and optimize the AI model. Then 362 radiographs were used to test the model's diagnostic performance. Its diagnostic accuracy was assessed using receiver operating characteristic (ROC) curves and measurement consistency using Bland-Altman plots. In 362 radiographs, the AI model's area under ROC curves, accuracy, sensitivity, and specificity for quality assessment was 0.993, 99.4% (360/362), 98.6% (138/140), and 100.0% (222/222), respectively. Compared with clinicians, the 95% limits of agreement (Bland-Altman analysis) for pelvic tilt index (PTI) and pelvic rotation index (PRI), as determined by the model, were -0.052-0.072 and -0.088-0.055, respectively. CONCLUSIONS: The artificial intelligence-assisted method was more efficient and highly consistent with clinical experts. This method can be used for real-time validation of the quality of pelvic radiographs in current picture archiving and communications systems (PACS). WHAT IS KNOWN: • Nonstandard pediatric radiographs with pelvic malposition make the correct diagnosis of developmental dysplasia of the hip (DDH) challenging. • Traditional manual assessment remains the only method available for screening standard pediatric pelvic radiographs, which is relatively laborious and potentially erroneous. WHAT IS NEW: • This study proposed an artificial intelligence-assisted model to assess the quality of pediatric pelvic radiographs accurately and efficiently. • We recommend the integration of the model into current picture archiving and communications systems (PACS) for real-time screening of standard pediatric pelvic radiographs.

Risk factors for misdiagnosis in children with developmental dysplasia of the hip: a retrospective single centre study.

OBJECTIVE: To investigate risk factors of misdiagnosis at the first visit of children with developmental dysplasia of the hip (DDH) who did not participate in hip ultrasound screening. METHODS: A retrospective review was conducted on children with DDH admitted to a tertiary hospital in northwestern China between January 2010 and June 2021. We divided the patients into the diagnosis and misdiagnosis groups according to whether they were diagnosed at the first visit. The basic information, treatment process and medical information of the children were investigated. We made a line chart of the annual misdiagnosis rate to observe the trend in the annual misdiagnosis rate. Univariate and multivariate logistic regression analyses were used to identify significant risk factors for missed diagnosis. RESULTS: A total of 351 patients met the inclusion criteria, including 256 (72.9%) patients in the diagnosis group and 95 (27.1%) patients in the misdiagnosis group. The line chart of the annual rate of misdiagnoses among children with DDH from 2010 to 2020 showed no significant change trend. Multiple logistic regression analysis showed that the paediatrics department (v the paediatric orthopaedics department: OR 0.21, p<0.001), the general orthopaedics department (v the paediatric orthopaedics department: OR 0.39, p=0.006) and the senior physician (v the junior physician: OR 2.47, p=0.006) on the misdiagnosis at the first visit of children were statistically significant. CONCLUSION: Children with DDH without hip ultrasound screening are prone to be misdiagnosed at their first visit. The annual misdiagnosis rate has not been significantly reduced in recent years. The department and title of the physician are independent risk factors for misdiagnosis.

Clinical thought-based software for diagnosing developmental dysplasia of the hip on pediatric pelvic radiographs.

Background: The common methods of radiographic diagnosis of developmental dysplasia of the hip (DDH) include measuring hip parameters and quantifying the degree of hip dislocation. However, clinical thought-based analysis of hip parameters may be a more effective way to achieve expert-like diagnoses of DDH. This study aims to develop a diagnostic strategy-based software for pediatric DDH and validate its clinical feasibility. Methods: In total, 543 anteroposterior pelvic radiographs were retrospectively collected from January 2017 to December 2021. Two independent clinicians measured four diagnostic indices to compare the diagnoses made by the software and conventional manual method. The diagnostic accuracy was evaluated using the receiver operator characteristic (ROC) curves and confusion matrix, and the consistency of parametric measurements was assessed using Bland-Altman plots. Results: In 543 cases (1,086 hips), the area under the curve, accuracy, sensitivity, and specificity of the software for diagnosing DDH were 0.988-0.994, 99.08%-99.72%, 98.07%-100.00%, and 99.59%, respectively. Compared with the expert panel, the Bland-Altman 95% limits of agreement for the acetabular index, as determined by the software, were -2.09°-2.91° (junior orthopedist) and -1.98°-2.72° (intermediate orthopedist). As for the lateral center-edge angle, the 95% limits were -3.68°-5.28° (junior orthopedist) and -2.94°-4.59° (intermediate orthopedist). Conclusions: The software can provide expert-like analysis of pelvic radiographs and obtain the radiographic diagnosis of pediatric DDH with great consistency and efficiency. Its initial success lays the groundwork for developing a full-intelligent comprehensive diagnostic system of DDH.

Quantification of femoral position on radiographic acetabular coverage in children.

An accurate assessment of the radiographic acetabular coverage is essential for clinical diagnosis or surgical decision-making in hip disorders. This study aimed to evaluate the effect of femoral position on acetabular coverage and to predict the actual acetabular coverage from nonstandard radiographs. A total of 21 children (34 hips) with normative acetabular coverage were screened in this retrospective study. The Mimics-based local-rotation fluoroscopy simulation method was used to tilt, incline, and rotate the femur in 4° increments within the range of femoral motion. The acetabular coverage, namely acetabular-head index (AHI) and center-edge angle (CEA), increased with femoral abduction but decreased with other motions. Compared to the femoral neutral position, no significant differences were identified in AHI with the rotation (range: 0°-16°) and in CEA with the tilt (range: -20°-4°), inclination (range: 0°-4°), or rotation (range: -8°-40°). The linear regression analysis showed that the CEA increased by about 0.20° for each 1° increase in femoral inclination and decreased by about 0.01°, 0.07°, 0.06°, or 0.07° for each 1° increase in internal rotation, external rotation, flexion, or extension, respectively. And a more significant change in AHI was observed. All femoral malpositions, especially the inclination, affected radiographic acetabular coverage in children. Therefore, each pelvic radiograph should assess potential femoral malpositioning before diagnosing hip disorders. This study will assist surgeons in predicting the acetabular coverage on nonstandard radiographs.

Clinical reliability and validity of a video-based markerless gait evaluation method.

Objective: To explore the reliability and validity of gait parameters obtained from gait assessment system software employing a human posture estimation algorithm based on markerless videos of children walking in clinical practice. Methods: Eighteen typical developmental (TD) children and ten children with developmental dysplasia of the hip (DDH) were recruited to walk along a designated sidewalk at a comfortable walking speed. A 3-dimensional gait analysis (3D GA) and a 2-dimensional markerless (2D ML) gait evaluation system were used to extract the gait kinematics parameters twice at an interval of 2 h. Results: The two measurements of the children's kinematic gait parameters revealed no significant differences (P > 0.05). Intra-class correlation coefficients (ICC) were generally high (ICC >0.7), showing moderate to good relative reliability. The standard error of measurement (SEM) values of all gait parameters measured by the two walks were 1.26°-2.91°. The system software had good to excellent validity compared to the 3D GA, with ICC values between 0.835 and 0.957 and SEM values of 0.87°-1.71° for the gait parameters measured by both methods. The Bland-Altman plot analysis indicated no significant systematic errors. Conclusions: The feasibility of the markerless gait assessment method using the human posture estimation-based algorithm may provide reliable and valid gait analysis results for practical clinical applications.

Closing-opening wedge osteotomy for the treatment of congenital kyphosis in children.

BACKGROUND: To evaluate the safety and effectiveness of posterior closed-open wedge osteotomy for treatment of congenital kyphosis in children. METHODS: Imaging and clinical data from January 2010 to December 2019 of posterior closed-open wedge osteotomy of congenital kyphosis with at least 2-year follow up was analyzed retrospectively. Perioperative indicators such as operation time, osteotomy site, osteotomy method and occurrence of complications, and imaging indicators were observed. The 3D printed models were used to measure the expanded distance of anterior edge vertebra and closed length of spinal canal line. The clinical effect was evaluated through SRS-22 questionnaires. RESULTS: There were 15 CK patients in this study. The osteotomy segments and details are as follows: 1 case each for T6-9 and L2, 2 cases at T11, 3 cases at T12, and 6 cases at L1. The average operation time was 314 min, the average blood loss was 970 mL, the average fusion range was 6.3 segments, and the average time of follow up was 70.5 months. The Cobb angle of local kyphosis was corrected from 65.6 ± 18.8° to 11.3 ± 7.1°(p < .001). The range of kyphosis correction was 40-90°, and average correction rate was 83.2% (67.7-95.7%). The correction was stable in follow-up, and the kyphotic angle was 11.0 ± 7.6 (p = .68). The preoperative SVA was 31.5 ± 21.8 mm, and the postoperative recovery was 18.0 ± 15.5, while the last follow-up was 9.1 ± 7.9. The p values were 0.02 and 0.07 respectively. By using 3D printed models, the expanded distance of anterior edge vertebra and closed length of spinal canal line were 14.5 ± 7.5 mm and 24.5 ± 8.0 mm respectively. Self-image and satisfaction in SRS-22 improved significantly. There was no recurrence of deformity and junctional kyphosis. CONCLUSIONS: The posterior closing-opening wedge osteotom for treatment of congenital kyphosis in children is satisfactory, if selected appropriately. During the longitudinal follow-up, the patients could achieve solid fusion and the correction could be well maintained.Evidence of Confidence: IVa.

Comparison of Transfer Learning Models in Pelvic Tilt and Rotation Measurement in Pediatric Anteroposterior Pelvic Radiographs.

The rotation and tilt of the pelvis during anteroposterior pelvic radiography can lead to misdiagnosis of developmental dysplasia of the hip (DDH) in children. At present, no method exists for accurately and conveniently measuring the precise rotation and tilt angles of pelvic on radiographs. The objective of this study was to develop several rotation and tilt measurement models using transfer learning and digital reconstructed radiographs (DRRs), and to compare their performances on pelvic radiographs. Based on the inclusion criteria, 30 of 92 children who underwent 3D hip CT scans at Xijing Hospital from 2015 to 2020 were included in the study. Using DRR techniques, radiographs were generated by rotating and tilting the pelvis in CT datasets at - 12 to 12° (projected every 3°) and were randomized to a 2:1:1 ratio of training dataset, validation dataset, and test dataset. Five pre-trained networks, including VGG16, Xception, VGG19, ResNet50 and InceptionV3 were used to develop pelvic rotation measurement models and tilt measurement models, and these models were trained with training dataset. The callback function was used during the training to slow down the learning rate when learning was stalled. Then, the validation set was used to optimize each model and compare their performances. At last, we tested the final performances of optimal rotation measurement model and optimal tilt measurement model on test dataset. The mean absolute error (MAE) was employed to assess the performance of the models. A total of 2430 pelvic DRRs were collected based on 30 CT datasets. Among 5 pre-trained transfer learning models, VGG16-Tilt achieved the best tilt prediction performance at the same BS and different LR. VGG16-Tilt model achieved its best performance on validation set at LR = 0.001 and BS = 4, and the final MAE on the test set was 0.5250°. In terms of rotation prediction, VGG16-Rotation also achieved the best performance, and it achieved its best performance on validation set at LR = 0.002 and BS = 8. The final MAE of VGG16-Rotation on the test set was 1.0731°. Pretrained transfer learning models worked well in predicting tilt and rotation angles of the pelvis on radiographs in children. Among them, VGG16-Tilt and VGG16-Rotation had the best effect in dealing with such problems despite their simple structures. These models deployed in devices can give orthopedic surgeons a powerful aid in DDH diagnosis.

Implant Preservation versus Implant Replacement in Revision Surgery for Adjacent Segment Disease After Thoracolumbar Instrumentation: A Retrospective Study of 43 Patients.

OBJECTIVE: To evaluate the mechanical properties of a new connector rod aiming to preserve implants in revision surgery (RS) for adjacent segment disease, a problematic complication of instrumented spinal fusion, and to assess its clinical applicability. METHODS: The mechanical properties of the connector-rod construct (implant preservation) and traditional rod construct (implant replacement) were evaluated and compared. Forty-three patients underwent RS for adjacent segment disease in the thoracolumbar spine with implant preservation or replacement, and radiological and clinical outcomes were assessed. RESULTS: Mechanical properties in group A were comparable to those in group B. Total mean time from prior surgery to RS was 6.86 ± 1.08 years. Surgical time and blood loss values of group A were 40.14% and 29.29% statistically significantly smaller than values of group B. In group B, 12% (3/25) of patients developed surgical site infections. In both groups, the visual analog scale leg score decreased significantly after RS. Early postoperative (at 1-month and 3-month follow-up) Oswestry Disability Index and visual analog scale back scores of group A were significantly lower than those of group B; the difference in the visual analog scale back score between groups was significant until the 6-month follow-up. No implant failures occurred, and spinal fusion was achieved in all cases. CONCLUSIONS: The connector rod is considered safe and can reduce the surgical time, blood loss, risk of complications, and medical costs. Better early postoperative clinical outcomes can be achieved with the rod owing to less surgical trauma.

Impairment of type H vessels by NOX2-mediated endothelial oxidative stress: critical mechanisms and therapeutic targets for bone fragility in streptozotocin-induced type 1 diabetic mice.

Rationale: Mechanisms underlying the compromised bone formation in type 1 diabetes mellitus (T1DM), which causes bone fragility and frequent fractures, remain poorly understood. Recent advances in organ-specific vascular endothelial cells (ECs) identify type H blood vessel injury in the bone, which actively direct osteogenesis, as a possible player. Methods: T1DM was induced in mice by streptozotocin (STZ) injection in two severity degrees. Bony endothelium, the coupling of angiogenesis and osteogenesis, and bone mass quality were evaluated. Insulin, antioxidants, and NADPH oxidase (NOX) inhibitors were administered to diabetic animals to investigate possible mechanisms and design therapeutic strategies. Results: T1DM in mice led to the holistic abnormality of the vascular system in the bone, especially type H vessels, resulting in the uncoupling of angiogenesis and osteogenesis and inhibition of bone formation. The severity of osteopathy was positively related to glycemic levels. These pathological changes were attenuated by early-started, but not late-started, insulin therapy. ECs in diabetic bones showed significantly higher levels of reactive oxygen species (ROS) and NOX 1 and 2. Impairments of bone vessels and bone mass were effectively ameliorated by treatment with anti-oxidants or NOX2 inhibitors, but not by a NOX1/4 inhibitor. GSK2795039 (GSK), a NOX2 inhibitor, significantly supplemented the insulin effect on the diabetic bone. Conclusions: Diabetic osteopathy could be a chronic microvascular complication of T1DM. The impairment of type H vessels by NOX2-mediated endothelial oxidative stress might be an important contributor that can serve as a therapeutic target for T1DM-induced osteopathy.

Plantar Pressure Distribution of Right and Left Foot in Bilateral Clubfoot Treated by Ponseti Method: A Correlation Analysis.

BACKGROUND Congenital clubfoot is a common pediatric orthopedic deformity that can be corrected by Ponseti method, and pedobarographic analysis has been used to assess the outcomes. However, the relationship between the plantar pressure distribution of the right and left foot in children with bilateral clubfoot has not been studied. In this study, the pedobarographic data of patients with bilateral clubfoot who were treated by the Ponseti method were reviewed, and a correlation analysis was conducted to clarify the relationship between the right and left foot. MATERIAL AND METHODS A retrospective cross-sectional study of children with bilateral clubfoot who were treated by the Ponseti method in infancy was performed, in which all the patients were available for clinical evaluation, and pedobarographic analysis was conducted on each patient after treatment. The Pearson's correlation coefficient (r) were calculated for all the measurements of the left and right foot. RESULTS A total of 20 children (mean age 6.9±1.07 years, range 4-8 years) with bilateral clubfoot who were treated by the Ponseti method were included. The Dimeglio and Pirani scores before and after treatment between the right and left foot were significantly correlated. All the pedobarographic measurements between the left and right foot were correlated, indicating different degrees of positive correlation. CONCLUSIONS The plantar pressure measurements between the 2 feet in patients with bilateral clubfoot were highly correlated before treatment, and a correlation was also observed after those patients were treated by the Ponseti method. We should take these correlations into consideration during study design and analysis of clubfoot cases.

Biomechanical study of space frame structure based on bone cement screw.

Stability of space frame structures with bone cement screw reinforcement by biomechanical testing was analyzed. Seven complete human spine specimens with osteoporosis were selected. Three specimens were separated into 18 vertebral bodies. Nine vertebral bodies were randomly selected and bone cement screws were implanted on both sides. Bone cement was used to form a bridge at the front end of the two screws (single vertebral group A). The other nine vertebral bodies were implanted with cement screws on both sides, but the front ends of the two screws were not bridged (single vertebral group B). The remaining spine specimens were used for biomechanical testing of the overall stability of the three-dimensional frame. The four specimens were osteotomized, and then two specimens were randomly selected. Bone cement screws were implanted on both sides of the vertebral body, and a bone cement bridge was formed at the front end of the two screws to establish a three-dimensional frame structure (multi-vertebral group A). The other two spine specimens were implanted with cement screws on both sides of the vertebral body, but the front ends of the two screws were not bridged (multi-vertebral group B). A statistical difference was found between the extractive force of bridged and non-bridged specimens. Group B showed some loosening of screws after the test. The stability of the triangle structure screw, which was formed after the bridge was established at the front end of the single-vertebral bone cement screw, was significantly enhanced. Moreover, the stability was significantly improved after the three-dimensional frame structure was established in the multi-vertebral body group, providing a new method for clinical improvement of the stability and reliability of internal fixation in patients with severe osteoporosis and spinal disease.

One-stage Surgical Treatment of Simultaneous Osteotomy and Asymmetric Lengthening on Short Femur with Severe Deformity of Genu Valgus.

This study aimed to discuss the effects of one stage surgical treatment by simultaneous osteotomy and asymmetric lengthening by Ilizarov external fixator on short femur with severe deformity of genu valgus. A total of 12 cases with unilateral deformities treated by simultaneous osteotomy and Ilizarov asymmetric lengthening on short femur with severe deformity of genu valgus were retrospectively analyzed from January 2006 to April 2015. The affected limbs were 2.5-11 cm (5.2 cm on average) short, the femorotibial angle was 135°-158° (146.3° on average), and the ankle interval was 15-43 cm (24.7 cm on average). The Paley method was used to determine the osteotomy plane (distal femur) of genu valgus. According to this standard, the bone union results were as follows: 11 had excellent and 1 had good, where 7 patients had excellent and 5 had good functional outcomes. One stage surgical treatment by simultaneous osteotomy and asymmetric lengthening on short femur with severe deformity of genu valgus was considered to be an effective and reliable method with better osteotomy union, less trauma and fewer complications.

Pedobarographic Analysis following Ponseti Treatment for Unilateral Neglected Congenital Clubfoot.

Recent trends have led to an interest in Ponseti treatment for correcting neglected congenital clubfoot. Although good clinical and functional outcomes have been reported, the plantar pressure distribution after the treatment of neglected clubfoot has not been explored yet. The present study aimed to investigate whether plantar pressures normalized following Ponseti treatment in patients with neglected congenital clubfoot. Pedobarographic, clinical, and functional examinations were performed in 22 children (aged, 91.0 ± 40.3 months) with unilateral neglected congenital clubfeet, treated using Ponseti method at 27.8 ± 12.1 months of age. Plantar pressure parameters were recorded using a Footscan pressure plate. The contact time, contact area, peak pressure, and pressure-time integral were determined. The data of the affected feet were compared with those of the unaffected feet and healthy controls. Although clinical and functional examinations showed satisfactory results according to the Dimeglio and Pirani scores, considerable differences in plantar pressure parameters were identified among the affected feet, unaffected feet, and healthy controls. Internal foot progression angle and a load transfer from the medial forefoot and hindfoot to the lateral forefoot and midfoot were observed in the affected feet. Future studies should attempt to investigate the factors accounting for plantar pressure deviations and the possible effect of these deviations on the lower limb musculoskeletal development of children.

Reliability of the Footscan® Platform System in Healthy Subjects: A Comparison of without Top-Layer and with Top-Layer Protocols.

The Footscan platform is a useful tool for plantar pressure measurement. However, there is still controversy over whether or not the platform should be covered by top-layer during the test. This study was designed to compare the reliability of the Footscan platform and identify the differences of the foot loading parameters between without top-layer (WOT) and with top-layer (WT) protocols. Measurements were taken from thirty-two healthy subjects. Participants were tested with a Footscan platform using the WOT and WT protocols. Three trials were performed during two separate testing sessions with a 7-day interval. Peak pressure, contact time, contact area, and pressure-time integral at ten foot zones were recorded and calculated for intra- and intersession reliability using intraclass correlation coefficients (ICCs) and coefficients of variation (CVs). The reliability and values of the analyzed parameters for the two protocols were compared. Both protocols produced a moderate to good level of intra- and intersession reliability. Compared with the WT protocol, the WOT protocol showed higher ICCs, lower CVs, and higher values in most of the parameters analyzed. The results suggest that the WOT protocol showed better reliability than the WT protocol. We recommend not using the top-layer when performing the plantar pressure test.

Influence of the shape of the micro-finite element model on the mechanical properties calculated from micro-finite element analysis.

Assessing the biomechanical properties of trabecular bone is of major biological and clinical significance for the research of bone diseases, fractures and their treatments. Micro-finite element (µFE) models are becoming increasingly popular for investigating the biomechanical properties of trabecular bone. The shapes of µFE models typically include cube and cylinder. Whether there are differences between cubic and cylindrical µFE models has not yet been studied. In the present study, cubic and cylindrical µFE models of human vertebral trabecular bone were constructed. A 1% strain was prescribed to the model along the superior-inferior direction. E values were calculated from these models, and paired t-tests were performed to determine whether these were any differences between E values obtained from cubic and cylindrical models. The results demonstrated that there were no statistically significant differences in the E values between cubic and cylindrical models, and there were no significant differences in Von Mises stress distributions between the two models. These findings indicated that, to construct µFE models of vertebral trabecular bone, cubic or cylindrical models were both feasible. Choosing between the cubic or cylindrical µFE model is dependent upon the specific study design.

Normal foot loading parameters and repeatability of the Footscan® platform system.

BACKGROUND: The Footscan® platform system is one of the most commonly used clinical tools for the measurement of the foot pressure. The present study was designed to assess the repeatability of the system and identify the range of loading parameters observed in the normal foot. METHODS: Measurements were collected from 32 healthy participants, 15 females and 17 males, twice at an interval of 1 week. Peak pressure (PP), contact time (CT), contact area (CA), pressure-time integral (PTI), and maximum force (MaF) were recorded; these parameters were investigated in 10 areas of the foot: medial heel, lateral heel, midfoot, first to fifth metatarsals, hallux, and toes 2-5. The intra-session repeatability was evaluated by calculating the intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) across the three repeated trials within the same session. The inter-session repeatability was assessed using the average of the three trials in each session to determine the ICCs and CVs. RESULTS: The ICCs showed moderate to good repeatability for every variable of interest, and the CVs were all <28%. The highest zones of PP were found under the second and third metatarsals, followed by the medial heel. The CT was 68.5-82.8% of the total stance time under the metatarsal heads. CA was highest under the midfoot, PTI was highest under the second metatarsal, and MaF was highest under the medial heel. CONCLUSIONS: Footscan® platform system was found to be repeatable. Thus, it can be used as a valuable tool in the assessment of plantar pressure distribution, and the normal values of the foot loading parameters identified in this study can be employed to provide a reference range for the gait analysis performed by the Footscan® system.

Adiponectin improves the osteointegration of titanium implant under diabetic conditions by reversing mitochondrial dysfunction via the AMPK pathway in vivo and in vitro.

Diabetes-induced reactive oxygen species (ROS) overproduction would result in compromised osteointegration of titanium implant (TI) and high rate of implant failure, yet the underlying mechanisms remain elusive. Adiponectin (APN) is a fat-derived adipocytokine with strong antioxidant, mitochondrial-protective and anti-diabetic efficacies. We hypothesized that mitochondrial dysfunction under diabetes may account for the oxidative stress in osteoblasts and titanium-bone interface (TBI) instability, which could be ameliorated by APN. To test this hypothesis, we incubated primary rat osteoblasts on TI and tested the cellular behaviors when subjected to normal milieu (NM), diabetic milieu (DM), DM+APN, DM+AICAR (AMPK activator) and DM+APN+Compound C (AMPK inhibitor). In vivo, APN or APN+Compound C were administered to diabetic db/db mice with TI implanted in their femurs. Results showed that diabetes induced structural damage, dysfunction and content decrease of mitochondria in osteoblasts, which led to ROS overproduction, dysfunction and apoptosis of osteoblasts accompanied by the inhibition of AMPK signaling. APN alleviated the mitochondrial damage by activating AMPK, thus reversing osteoblast impairment and improving the osteointegration of TI evidenced by Micro-CT and histological analysis. Furthermore, AICAR showed beneficial effects similar to APN treatment, while the protective effects of APN were abolished when AMPK activation was blocked by Compound C. This study clarifies mitochondrial dysfunction as a crucial mechanism in the impaired bone healing and implant loosening in diabetes, and provides APN as a novel promising active component for biomaterial-engineering to improve clinical performance of TI in diabetic patients. STATEMENT OF SIGNIFICANCE: The loosening rate of titanium implants in diabetic patients is high. The underlying mechanisms remain elusive and, with the rapid increase of diabetic morbility, efficacious strategies to mitigate this problem have become increasingly important. Our study showed that the mitochondrial impairment and the consequent oxidative stress in osteoblasts at the titanium-bone interface (TBI) play a critical role in the diabetes-induced poor bone repair and implant destabilization, which could become therapeutic targets. Furthermore, adiponectin, a cytokine, promotes the bio-functional recovery of osteoblasts and bone regeneration at the TBI in diabetes. This provides APN as a novel bioactive component used in material-engineering to promote the osteointegration of implants, which could reduce implant failure, especially for diabetic patients.