Reconstructing three-dimensional (3D) models from two-dimensional (2D) images is necessary for preoperative planning and the customization of joint prostheses. However, the traditional statistical modeling reconstruction shows a low accuracy due to limited 3D characteristics and information loss. In this study, we proposed a new method to reconstruct the 3D models of femoral images by combining a statistical shape model with Laplacian surface deformation, which greatly improved the accuracy of the reconstruction. In this method, a Laplace operator was introduced to represent the 3D model derived from the statistical shape model. By coordinate transformations in the Laplacian system, novel skeletal features were established and the model was accurately aligned with its 2D image. Finally, 50 femoral models were utilized to verify the effectiveness of this method. The results indicated that the precision of the method was improved by 16.8%–25.9% compared with the traditional statistical shape model reconstruction. Therefore, the method we proposed allows a more accurate 3D bone reconstruction, which facilitates the development of personalized prosthesis design, precise positioning, and quick biomechanical analysis.
Objective To explore the clinical and inflammatory characteristics and risk factors of severe asthma to improve clinicians' awareness of the disease. Methods The general information of patients with asthma who visited the Department of Respiratory Medicine, the First Hospital of Shanxi Medical University from May 2018 to May 2021, as well as the diagnosis and treatment of asthma, personal history, comorbidities, auxiliary examination, asthma control test (ACT) score were collected. A total of 127 patients were included, including 40 in the severe asthma group and 87 in the mild-to-moderate asthma group. Chi-square test, independent sample t test and logistic regression were used to analyze the clinical characteristics, inflammatory markers and risk factors of severe asthma. Results Compared with the patients with mild to moderate asthma, the patients with severe asthma were more older (51.0±12.0 years vs 40.7±12.8 years, P<0.05), had more smokers (32.5% vs. 14.9%, P<0.05), and more males (67.5% vs. 40.2%, P<0.05). The patients with severe asthma got poor FEV1%pred [(56.1±23.8)% vs. (93.2±18.0)%, P<0.05] and FEV1/FVC [(56.7±13.2)% vs. (75.8±9.0)%, P<0.05)], and more exacerbations in the previous year (2.7±3.1 vs. 0.1±0.4, P<0.05), lower ACT score (14.4±3.7 vs. 18.0±5.0, P<0.05), and higher blood and induced sputum eosinophil counts [(0.54±0.44)×109/L vs. (0.27±0.32)×109/L, P<0.05; (25.9±24.2)% vs. (9.8±17.5)%, P<0.05]. There was no significant difference in the proportion of neutrophils in the induced sputum or FeNO between the two groups (P>0.05). Analysis of related risk factors showed that smoking (OR=2.740, 95%CI 1.053 - 7.130), combined with allergic rhinitis (OR=14.388, 95%CI 1.486 - 139.296) and gastroesophageal reflux (OR=2.514, 95%CI 1.105 - 5.724) were risk factors for severe asthma. Conclusions Compared with patients with mild to moderate asthma, patients with severe asthma are characterized by poor lung function, more exacerbations, and a dominant eosinophil inflammatory phenotype, which is still poorly controlled even with higher level of treatment. Risk factors include smoking, allergic rhinitis, and gastroesophageal reflux, etc.
The human femur is in a relatively complex mechanical environment, subject to the combined effects of multiple factors such as mechanical loads from movement and weight-bearing, as well as changes in the body fluid environment in daily life. In in vitro testing cases of the femur (e.g., testing of distal femoral fractures), changes in load conditions usually significantly affect the mechanical properties of the overall structure. However, there is currently no systematic evaluation standard for in vitro mechanical performance testing of the femur. Therefore, this paper established four human femur models (model A~model D) constructed based on computed tomography (CT) under different load environments, as well as two artificially synthesized femur models (the finite-element model and the experimental model) under the same load environment. Among them, for the human femur models, model A was configured to apply hip joint contact forces together with all muscle forces to approximate the real in vivo mechanical environment, model B was applied with hip joint contact force and abductor muscle force, model C was only applied with hip joint contact force, and model D was subjected to an equivalent resultant force. For the artificially synthesized femur models, both the finite-element model and the experimental model were applied with the same equivalent resultant force as model D. Comparative analyses revealed that model D exhibited femoral head displacement and stress-strain distributions similar to Model A, indicating its suitability as an equivalent in vitro test model. Further comparison between the finite-element and experimental synthetic femur models yielded consistent mechanical responses, thereby validating the equivalent model. In summary, it is hoped that the findings of this study will provide a reference for establishing a systematic, tiered preclinical evaluation system for hip prostheses/implants in the future.
A certain degree of varus alignment is physiological in the native knee, and alignment strategies such as kinematic and functional alignment permit residual postoperative varus. However, identical total varus angles may result from varying combinations of femoral and tibial varus, whose biomechanical implications for implant loading and ligament stress remain unclear. This study aims to investigate the biomechanical effects of different femoral–tibial varus configurations in total knee arthroplasty (TKA). Using combined geometric modeling and finite element analysis, TKA models with different varus combinations were constructed to evaluate changes in limb moment arms, polyethylene insert stress, and ligament forces during static knee flexion (0°–90°). Results demonstrated that a higher proportion of femoral varus, under equivalent total varus and flexion angles, led to reduced maximum polyethylene stress and decreased tension in the medial collateral ligament (MCL) and anterolateral ligament complex (ALL). Knee flexion angle had a more significant impact on polyethylene stress than varus: stress increased by approximately 2.48 times at 90° flexion compared to 0°, whereas 12° varus increased stress by only approximately 14%. The ALL experienced the greatest tensile load during flexion, indicating a key stabilizing role. In conclusion, optimizing the combination of femoral and tibial varus may help redistribute loads and improve implant longevity. This study reveals, from a biomechanical perspective, how different varus configurations affect stress distribution in the prosthesis and surrounding soft tissues, suggesting that intraoperative osteotomy strategies should comprehensively consider the combined alignment of the femur and tibia.