Biomechanical Effects Research Articles

Biomechanical effects of men’s dress shoes made with bacterial cellulosic composite

PurposeThis study aimed to compare the performance of sustainable shoes made with bacterial cellulosic composite and commercial leather shoes using an experimental research design. The two specific research objectives were: (1) to examine the basic material properties of multi-layered bacterial cellulosic materials (MBC), which include green tea-based cellulosic (GBC) mats, hemp fabrics, and denim fabrics, in comparison with those of two-layered leathers (MCP) consisting of calf-skin and pig-skin – commonly used in shoe manufacturing; and (2) to explore wearers’ performance in the two types of shoes by assessing quantitative kinematic and kinetic parameters of lower body movements.Design/methodology/approachThis study focused on assessing the basic materials testing and performance of sustainable shoes through a biomechanical approach, in contrast to commercially available leather shoes, through human wear trials. In this study, green tea-based cellulosic (GBC) mats were developed using the optimal combination of ingredients for cellulose growth. Subsequently, the GBC, denim fabric (100% cotton), and 100% hemp fabric were combined to create multi-layered bacterial cellulosic materials (MBC) as an alternative to leather. Additionally, calf-skin and pig-skin leathers were utilized to produce a commercially available two-layered leather (MCP), commonly employed in shoe manufacturing. 37 of the 42 human subjects who participated in wear testing were collected. A paired t-test was conducted to determine whether significant mean differences existed between the two shoe types, a paired t-test was conducted.FindingsTo develop a biodegradable and compostable material that could be used as a leather alternative for the footwear industry, we proposed MBC and examined its properties compared with those of MCP, a product often used when making shoes. These findings confirmed the similar properties of MBC and MCP from the material testing and the possibility of using a men’s sustainable shoe prototype as a leather alternative, in terms of kinematics and kinetics.Practical implicationsThe new multi-layered bacterial cellulosic materials (MBC) could be an alternative to commercial leathers such as innovative sustainable material construction, advanced design, and advanced techniques to optimize the overall performance of sustainable footwear.Originality/valueInvestigating the integration of smart textile technologies, ergonomic design principles, and personalized customization will contribute to developing MBC and making sustainable shoes using MBC compared with commercial leather shoes. This study provides valuable insights into further refinement and innovation in the sustainable footwear industry.

Myocardial biomechanical effects of fetal aortic valvuloplasty.

Fetal critical aortic stenosis with evolving hypoplastic left heart syndrome (CAS-eHLHS) can progress to a univentricular (UV) birth malformation. Catheter-based fetal aortic valvuloplasty (FAV) can resolve stenosis and reduce the likelihood of malformation progression. However, we have limited understanding of the biomechanical impact of FAV and subsequent LV responses. Therefore, we performed image-based finite element (FE) modeling of 4 CAS-eHLHS fetal hearts, by performing iterative simulations to match image-based characteristics and then back-computing physiological parameters. We used pre-FAV simulations to conduct virtual FAV (vFAV) and compared pre-FAV and post-FAV simulations. vFAV simulations generally enabled partial restoration of several physiological features toward healthy levels, including increased stroke volume and myocardial strains, reduced aortic valve (AV) and mitral valve regurgitation (MVr) velocities, reduced LV and LA pressures, and reduced peak myofiber stress. FAV often leads to aortic valve regurgitation (AVr). Our simulations showed that AVr could compromise LV and LA depressurization but itcould alsosignificantly increase stroke volume and myocardial deformational stimuli. Post-FAV scans and simulations showed FAV enabled only partial reduction of the AV dissipative coefficient. Furthermore, LV contractility and peripheral vascular resistance could change in response to FAV, preventing decreases in AV velocity and LV pressure, compared with what would be anticipated from stenosis relief. This suggested that case-specific post-FAV modeling is required to fully capture cardiac functionality. Overall, image-based FE modeling could provide mechanistic details of the effects of FAV, but computational prediction of acute outcomes was difficult due to a patient-dependent physiological response to FAV.

Effect of Plate Configuration in the Primary Stability of Osteotomies and Biological Reconstructions of Femoral Defects: Finite-Element Study

Background/objective: Osteosynthesis is an alternative treatment for stabilizing femur-bone traumas. The initial stability of the fixation systems is one of the biomechanical parameters affecting implant failure and bone union, especially in surgeries of intercalary reconstructions after the removal of bone tumors. This study aimed to investigate the initial biomechanical effect of using one or two osteosynthesis plate configurations for femoral fixation and the effect of fastening the allograft to the osteosynthesis plate in the case of femoral allograft reconstructions. Methods: Three finite-element models of a femur with three different fixation conditions for a transverse osteotomy in the middle of the diaphysis, i.e., using one and two osteosynthesis plates and an intercalary allograft, were constructed. An eight-hole compression plate and a six-hole second plate were used to simulate osteosynthesis plates. The plate screws were tightened previously to the loading, and the tightening sequences simulate the bolt-tightening procedure in a surgical environment. The models were imported into the ADINA System for nonlinear analysis, using compression loads applied over the femur head. Results: Models with the dual fixation systems had the most outstanding compression stiffness. The femur head movement in the dual plate system was 24.8% smaller than in the single plate system. A statistical analysis of a region of interest (VOI) placed in the femur diaphysis showed that the biomechanical effect of using the dual plate system is smaller in the osteotomy region than at the femur head, e.g., a displacement average decrease of only 5% between the two systems, while the maximum value decreases by 26.8%. The allograft fixation to the second osteosynthesis plate leads to an improvement in the system stability. Conclusions: The results presented in this work show that including the bolt analysis in the femoral diaphysis osteotomy fixation will allow for capturing the nonlinear behavior of the osteotomy region more realistically. The stability of the intercalary reconstruction of the femoral diaphysis was higher when the allograft was fastened to the second osteosynthesis plate.

Short-term lumbar disc and lumbar stability changes of one-hole split endoscope technique treatment of spinal stenosis

ObjectiveInvestigating the early biomechanical effects of the one-hole split endoscope (OSE) technique on lumbar spine after decompression surgery.MethodsA retrospective analysis was conducted on 66 patients with lumbar spinal stenosis (LSS) who underwent OSE technique surgery at the affiliated hospital of Binzhou Medical University from September 2021 to September 2022. The patients had complete postoperative follow-up records. The mean age was (51.73 ± 12.42) years, including 33 males and 33 females. The preoperative and postoperative imaging data were analyzed, including disc height (DH), foraminal height (FH), lumbar lordosis angle (LLA), changes in disc angle, anterior-posterior translation distance, and lumbar intervertebral disc Pfirrmann grading. The visual analogue scale (VAS) was applied to evaluate the severity of preoperative, postoperative day 1, postoperative 3 months, and final follow-up for back and leg pain. The Oswestry Disability Index (ODI) was applied to assess the functionality at all the listed time points. The modified MacNab criteria were applied to evaluate the clinical efficacy at the final follow-up.ResultsIn 66 patients, there were statistically significant differences (p < 0.05) in DH and FH at the affected segments compared to preoperative values, whereas no significant differences (p > 0.05) were found in DH and FH at the adjacent upper segments compared to preoperative values. There was no statistically significant difference in the LLA compared to preoperative values (p > 0.05). Both the affected segments and adjacent upper segments showed statistically significant differences in Pfirrmann grading compared to preoperative values (p < 0.05). There were no statistically significant differences in the changes in disc angle or anterior-posterior translation distance in the affected or adjacent segments compared to preoperative values (p > 0.05). The VAS scores for back and leg pain, as well as the ODI, significantly improved at all postoperative time points compared to preoperative values. Among the comparisons at different time points, the differences were statistically significant (p < 0.05). The clinical efficacy was evaluated at the final follow-up using the modified MacNab criteria, with 51 cases rated as excellent, 8 cases as good, and 7 cases as fair, resulting in an excellent-good rate of 89.39%.ConclusionsThe OSE technique, as a surgical option for decompression in the treatment of LSS, has no significant impact on lumbar spine stability in the early postoperative period. However, it does have some effects on the lumbar intervertebral discs, which may lead to a certain degree of degeneration.

Experimental investigation of tension-reducing effectiveness of keystone perforator island flap

Background and aim. Nowadays, the reconstruction of large and complex defects with keystone perforator island flaps (KPIF) has gained popularity in plastic and reconstructive surgery. The keystone perforator island flap was described as a curvilinear shaped trapezoidal design flap, with two V-Y advancement flaps end-to-side. It is a multiperforator advancement flap, based on multiple fasciocutaneous or musculocutaneous perforators, described by Behan in 2003. These flaps have a simple harvest technique, an easy-to-implement design, and they are time and cost-saving. Their blood supply lends a versatile and robust character, with less complications. Nonetheless, their biomechanical properties and effectiveness are unclear, the wound-closure tension-reducing effect is not well documented in existing literature. The present study aims to investigate the wound closure tension-reducing effect of type I, type IIA, type Sidney Melanoma Unit I (SMU) and type SMU II KPIFs. The main purpose of this study was to clarify the tension-reducing effect of the KPIF technique, which can contribute to the understanding of the biomechanical benefits of the KPIF. Methods. This is an experimental, in vivo study, based on twelve white race porcine models (PIC-FII-377), as their anatomy and wound healing process is very similar to that of humans. In this study, 42 wounds that could not be closed by primary wound closure, known as ‘unclosable’ elliptical defects, were created in six different anatomical regions. The criteria used for not achieving primary wound closure were the breaking of 0 nylon suture or the edges of the wound. Each defect was closed with different types of keystone perforator island flap: type I, type IIA, type Sydney Melanoma Unit I and type Sydney Melanoma Unit II. Keystone perforator island flaps were used in 42 cases. Intraoperative tissue tension was measured by an AXIS FB50, 50 N force gauge tensiometer. In all cases a wide elliptical excision was performed for the primary defect. Before reconstruction, tissue tension was measured across the widest point of the elliptical primary defect. Skin incision was performed for the first flap, without division of deep fascia. After preparing first flap, tension was measured at the widest point of the wound. Furthermore, deep fascia for the second flap was divided, tissue tension across the widest point of the primary defect was measured. Finally, tension was measurement across the widest point of the donor-site after closure of the defect-side flap and V–Y closure of either end of keystone perforator island flap. Results. In this study were included 12 porcine model (PIC-FII-377). A number of 42 keystone perforator island flaps were performed in this study, in six different anatomical regions, ranging between 3.3 x 12 cm and 16 x 30 cm. All elliptical defects were unclosable, with varying sizes ranging between 2 x 4 cm and 8 x 20 cm. The mean tension that was required to close all wounds with primary closure initially was 24.51 N ± 10.73 N. After using a type I KPIF a tension decrease of -7.04 N ± 4.93 N was seen, in the case of type IIA KPIF the tension decreased to -12.43 N± 5.63 N. Furthermore, after reconstruction with type SMU I KPIF the tension decreased to -7.38N ± 5.21N. After using a type SMU II KPIF a tension decrease of -10.52 N± 5.74 N was seen. Conclusions. The main purpose of this study was to clarify the tension-reducing effect of the KPIF technique, which can contribute to the understanding of the biomechanical benefits of the KPIF. The outcomes of the present study suggest that type I, type IIA, type SMU I, and SMU II of keystone perforator island flaps have a significant tension-reducing effects, especially the technique that involves the division of the deep fascia. The results of this experimental research thoroughly explain the benefits of these flaps. The effectiveness of the flap and doubts on biomechanical properties have not been answered so far. It will encourage more plastic surgeons to use the flap, especially given its proven benefits.  

Biomechanical effects of clear aligner with different shape design at extraction space area during anterior teeth retraction.

This study aimed to investigate the biomechanical effects of clear aligner (CA) with different shape designs at extraction space (CAES) area during space closing. A finite-element method (FEM) model of mandibular dentition, periodontal ligaments, attachments, and corresponding CA was established. The connecting rod design of CAES was modelled for the control group. Eight test groups with different heights of CAES from -4 mm to +4 mm were designed. Tooth displacement tendencies were calculated. The maximum principal stress in PDLs, teeth, and CAs was analysed. Both global coordinate system and local coordinate system were also used to evaluate individual tooth movements. Across all groups, stresses concentrated on the lingual outer surface of CAESs. For the lowered CAES groups, both the stress value and the stress distribution area at CAESs were increased. The lowered CAES groups showed reduced movement in anterior teeth and less tipping tendency of the canines. The shape of CAES has a biomechanical impact on anterior teeth movement and should be considered in aligner design. The results suggest that increasing the height of CAES can enhance anterior teeth retraction, while lowered CAES may facilitate controlled root movement. Changes in the shape of CAES represent a potential direction for biomechanical improvement of clear aligner in extraction cases and are worth exploring.

Classification of Osteophytes Occurring in the Lumbar Intervertebral Foramen.

Surgeons have limited knowledge of the lumbar intervertebral foramina. This study aimed to classify osteophytes in the lumbar intervertebral foramen and to determine their pathoanatomical characteristics, discuss their potential biomechanical effects, and contribute to developing surgical methods. We conducted a retrospective, non-randomized, single-center study involving 1224 patients. The gender, age, and anatomical location of the osteophytes in the lumbar intervertebral foramina of the patients were recorded. Two hundred and forty-nine (20.34%) patients had one or more osteophytes in their lumbar 4 and 5 foramina. Of the 4896 foramina, 337 (6.88%) contained different types of osteophytes. Moreover, four anatomical types of osteophytes were found: mixed osteophytes in 181 (3.69%) foramina, osteophytes from the lower endplate of the superior vertebrae in 91 (1.85%) foramina, osteophytes from the junction of the pedicle and lamina of the upper vertebrae in 39 foramina (0.79%), and osteophytes from the upper endplate of the lower vertebrae in 26 (0.53%) foramina. The L4 foramen contained a significantly higher number of osteophytes than the L5 foramen. Osteophyte development increased significantly with age, with no difference between males and females. The findings show that osteophytic extrusions, which alter the natural anatomical structure of the lumbar intervertebral foramina, are common and can narrow the foramen.

Finite element analysis of biomechanical effects of percutaneous cement discoplasty in scoliosis

ObjectiveTo investigate the effect of bone cement on the vertebral body and biomechanical properties in percutaneous cement discoplasty (PCD) for degenerative lumbar disc disease.MethodsThree-dimensional reconstruction of L2 ~ L3 vertebral bodies was performed in a healthy volunteer, and the corresponding finite element model of the spine was established. Biomechanical analysis was performed on the changes in stress distribution in different groups of models by applying quantitative loads.ResultsModels with percutaneous discoplasty (PCD) showed improved stability under various stress conditions, and intervertebral foraminal heights were superior to models without discoplasty.ConclusionCement discoplasty can improve the stability of the vertebral body to a certain extent and restore a certain height of the intervertebral foramen, which has a good development prospect and potential.

Tumor Biomechanics Alters Metastatic Dissemination of Triple Negative Breast Cancer via Rewiring Fatty Acid Metabolism.

In recent decades, the role of tumor biomechanics on cancer cell behavior at the primary site has been increasingly appreciated. However, the effect of primary tumor biomechanics on the latter stages of the metastatic cascade, such as metastatic seeding of secondary sites and outgrowth remains underappreciated. This work sought to address this in the context of triple negative breast cancer (TNBC), a cancer type known to aggressively disseminate at all stages of disease progression. Using mechanically tuneable model systems, mimicking the range of stiffness's typically found within breast tumors, it is found that, contrary to expectations, cancer cells exposed to softer microenvironments are more able to colonize secondary tissues. It is shown that heightened cell survival is driven by enhanced metabolism of fatty acids within TNBC cells exposed to softer microenvironments. It is demonstrated that uncoupling cellular mechanosensing through integrin β1 blocking antibody effectively causes stiff primed TNBC cells to behave like their soft counterparts, both in vitro and in vivo. This work is the first to show that softer tumor microenvironments may be contributing to changes in disease outcome by imprinting on TNBC cells a greater metabolic flexibility and conferring discrete cell survival advantages.

Numerical study of osteophyte effects on preoperative knee functionality in patients undergoing total knee arthroplasty.

Osteophytes are routinely removed during total knee arthroplasty, yet the preoperative planning currently relies on preoperative computed tomography (CT) scans of the patient's osteoarthritic knee, typically including osteophytic features. This complicates the surgeon's ability to anticipate the exact biomechanical effects of osteophytes and the consequences of their removal before the operation. The aim of this study was to investigate the effect of osteophytes on ligament strains and kinematics, and ascertain whether the osteophyte volume and location determine the extent of this effect. We segmented preoperative CT scans of 21 patients, featuring different osteophyte severity, using image-based active appearance models trained to identify the osteophytic and preosteophytic bone geometries and estimate the cartilage thickness in the segmented surfaces. The patients' morphologies were used to scale a template musculoskeletal knee model. Osteophytes induced clinically relevant changes to the knee's functional behavior, but these were variable and patient-specific. Generally, severe osteophytic knees significantly strained the oblique popliteal ligament (OPL) and posterior capsule (PC) relative to the preosteophytic state. Furthermore, there was a marked effect on the lateral collateral ligament and anterolateral ligament (ALL) strains compared to mild and moderate osteophytic knees, and concurrent alterations in the tibial lateral-medial translation and external-internal rotation. We found a strong correlation between the OPL, PC, and ALL strains and posterolateral condylar and tibial osteophytes, respectively. Our findings may have implications for the preoperative planning in total knee arthroplasty, toward reproducing the physiological knee biomechanics as close as feasibly possible.

Innovative Design and Development of Personalized Ankle-Foot Orthoses for Survivors of Stroke With Equinovarus Foot: Protocol for a Feasibility and Comparative Trial.

Ankle-foot orthoses (AFOs) are vital in gait rehabilitation for patients with stroke. However, many conventional AFO designs may not offer the required precision for optimized patient outcomes. With the advent of 3D scanning and printing technology, there is potential for more individualized AFO solutions, aiming to enhance the rehabilitative process. This nonrandomized trial seeks to introduce and validate a novel system for AFO design tailored to patients with stroke. By leveraging the capabilities of 3D scanning and bespoke software solutions, the aim is to produce orthoses that might surpass conventional designs in terms of biomechanical effectiveness and patient satisfaction. A distinctive 3D scanner, complemented by specialized software, will be developed to accurately capture the biomechanical data of leg movements during gait in patients with stroke. The acquired data will subsequently guide the creation of patient-specific AFO designs. These personalized orthoses will be provided to participants, and their efficacy will be compared with traditional AFO models. The qualitative dimensions of this experience will be evaluated using the Quebec User Evaluation of Satisfaction With Assistive Technology (QUEST) assessment tool. Feedback from health care professionals and the participants will be considered throughout the trial to ensure a rounded understanding of the system's implications. Spatial-temporal parameters will be statistically compared using paired t tests to determine significant differences between walking with the personalized orthosis, the existing orthosis, and barefoot conditions. Significant differences will be identified based on P values, with P<.05 indicating statistical significance. The Statistical Parametric Mapping method will be applied to graphically compare kinematic and kinetic data across the entire gait cycle. QUEST responses will undergo statistical analysis to evaluate patient satisfaction, with scores ranging from 1 (not satisfied) to 5 (very satisfied). Satisfaction scores will be presented as mean and SD values. Significant variations in satisfaction levels between the personalized and existing orthosis will be assessed using a Wilcoxon signed rank test. The anticipation is that the AFOs crafted through this innovative system will either match or outperform existing orthoses in use, with higher patient satisfaction rates. Embracing the synergy of technology and biomechanics may hold the key to revolutionizing orthotic design, with the potential to set new standards in patient-centered orthotic solutions. However, as with all innovations, a balanced approach, considering both the technological possibilities and individual patient needs, will be paramount to achieving optimal outcomes. PRR1-10.2196/52365.

Intraocular lens power calculation: angle κ and ocular biomechanics

Purpose: To study the effect of ocular biomechanics on the prediction error of intraocular lens (IOL) power calculation. Setting: Centro Hospitalar Universitário do Porto, Porto, Portugal. Design: Prospective longitudinal study. Methods: This study included 67 subjects. Before cataract surgery subjects underwent biometry with IOLMaster 700 and biomechanical analysis with Corvis Scheimpflug technology. The targeted spherical equivalent was calculated with SRK-T and Barrett Universal II. Associations between prediction error (PE), absolute prediction error (AE), and biometric and biomechanical parameters were performed with stepwise multivariate linear correlation analysis. Results: Using the SRKT formula, there was association between PE and Corvis Biomechanical Index (CBI, B = −0.531, P = .011) and between AE and the horizontal offset between the center of the pupil and the visual axis (angle κ, B = −0.274, P = .007). Considering the Barret Universal II formula, PE was independently associated with anterior chamber depth (B = −0.279, P = .021) and CBI (B = −0.520, P = .013) and AE was associated with angle κ (B = −0.370, P = .007). Conclusions: A large angle κ may reduce the predictability of IOL power calculation. Ocular biomechanics likely influence the refractive outcomes after IOL implantation. This study showed that eyes with softer corneal biomechanics had more myopic PE. This may relate to anteriorization of the effective lens position. Dynamic measurements may be the way to progress into future formulas.

The biomechanical effect of lumbopelvic distance reduction on reconstruction after total sacrectomy: a comparative finite element analysis of four techniques

Background ContextFollowing total sacrectomy, lumbopelvic reconstruction is essential to restore continuity between the lumbar spine and pelvis. However, to achieve long-term clinical stability, bony fusion between the lumbar spine and the pelvic ring is crucial. Reduction of the lumbopelvic distance can promote successful bony fusion. Although many lumbopelvic reconstruction techniques (LPRTs) have been previously analyzed, the biomechanical effect of lumbopelvic distance reduction (LPDR) has not been investigated yet. PurposeTo evaluate and compare the biomechanical characteristics of four different LPRTs while considering the effect of LPDR. Study Design/SettingA comparative finite element (FE) study. MethodsThe FE models following total sacrectomy were developed to analyze four different LPRTs, with and without LPDR. The closed-loop reconstruction (CLR), the sacral-rod reconstruction (SRR), the four-rod reconstruction (FRR), and the improved compound reconstruction (ICR) techniques were analyzed in flexion, extension, lateral bending, and axial rotation. Lumbopelvic stability was assessed through the shift-down displacement and the relative sagittal rotation of L5, while implant safety was evaluated based on the stress state at the bone-implant interface and within the rods. ResultsRegardless of LPDR, both the shift-down displacement and relative sagittal rotation of L5 consistently ranked the LPRTs as ICR<SRR<FRR<CLR, with ICR being the stiffest for both parameters. LPDR decreased the shift-down displacement values by 25% in CLR, by 61% in SRR, by 15% in FRR, and by 46% in ICR, as well as reduced the relative sagittal rotation values by 21% in CLR, by 73% in SRR, by 11% in FRR, and by 53% in ICR. Considering the stress at the bone-implant interface, without LPDR, the ICR yielded the smallest stress values for flexion, lateral bending, and axial rotation with 131.4 MPa, 68.2 MPa, and 70.3 MPa, respectively, and the second smallest in extension with 36.1 MPa. Due to LPDR, these stress values were reduced by 31% in flexion, by 17% in extension, by 29% in lateral bending, and by 29% in axial rotation. Within the rods, without LPDR, the ICR yielded the smallest stress values for flexion, extension, lateral bending, and axial rotation with 346.5 MPa, 108.0 MPa, 186.2 MPa, and 199.7 MPa, respectively. With LPDR, these stress values were reduced by 16% in flexion, by 9% in extension, by 11% in lateral bending, and by 12% in axial rotation. ConclusionsLPDR significantly improved both lumbopelvic stability and implant safety in all reconstruction techniques after total sacrectomy. LPDR reduced the shift-down displacement of L5, the relative sagittal rotation of L5, and the stress values at the bone-implant interface. Furthermore, in the ICR and SRR techniques, LPDR decreased the peak stress values within the rods. All four investigated LPRTs demonstrated suitability for lumbopelvic reconstruction, with the ICR technique exhibiting the highest lumbopelvic stiffness. Clinical SignificanceLPDR creates a biomechanically advantageous environment following total sacrectomy; therefore, it has the potential to impact the design of custom-made 3D-printed or traditional LPRTs. However, to confirm the findings of the current FE study, long-term clinical trials are recommended.

404 Mechanisms of a Dynamic Stability Protocol for Persons with Thumb Osteoarthritis

OBJECTIVES/GOALS: Our aims are to 1) describe changes in thumb Carpometacarpal (CMC1) joint stability following an 8-week clinic-based dynamic stability exercise program using computerized tomography (CAT) and 2) to evaluate the agreement between ultrasound and CAT (reference standard) when quantifying thumb CMC stability. METHODS/STUDY POPULATION: Aim 1: We have enrolled 13/49 participants in a prospective pre-post interventional study of an 8-week clinic-based occupational therapy dynamic stability program. The primary outcome will be change in stability (thumb metacarpal subluxation in mm) when forcefully loading the thumb as per CAT from pre-treatment to post-treatment at 9 weeks. Aim 2: Same 49 participants are undergoing a one-time ultrasound during baseline assessment. Agreement of ultrasound and CAT measurements (thumb metacarpal subluxation in mm) will be assessed by the Bland-Altman method. RESULTS/ANTICIPATED RESULTS: Exercise is a first-line treatment of CMC1 OA yet there is insufficient evidence to support this. Progression of CMC1 OA is characterized by altered joint mechanics. Joint replacement surgery may reduce pain but often worsens thumb mechanics and overall hand function. This study is the first to test the sustained biomechanical effects of non-invasive thumb exercises. Should these benefits exist, this will further support exercise as a first-tier intervention. Should ultrasound be a suitable proxy for CAT, therapists/physicians could monitor thumb CMC mechanics in response to treatment without risk of radiation exposure. We anticipate 1) a statistically significant reduction in thumb CMC subluxation at 9 weeks follow up and 2) high agreement between sonographic and CAT measures of thumb stability. DISCUSSION/SIGNIFICANCE: This study will lay the foundation for future work and may offer critical support for the use of a non-pharmacological and non-surgical approach as first-line treatment of a highly disabling disease. Future study should include controlled trials where hand function, activity limitation, disease progression, and costs are the outcomes in interest.

The frictional energy absorber effectiveness and its impact on the pressure ulcer prevention performance of multilayer dressings.

Pressure ulcers including heel ulcers remain a global healthcare concern. This study comprehensively evaluates the biomechanical effectiveness of the market-popular ALLEVYN® LIFE multilayer dressing in preventing heel ulcers. It focuses on the contribution of the frictional sliding occurring between the non-bonded, fully independent layers of this dressing type when the dressing is protecting the body from friction and shear. The layer-on-layer sliding phenomenon, which this dressing design enables, named here the frictional energy absorber effectiveness (FEAE), absorbs approximately 30%-45% of the mechanical energy resulting from the foot weight, friction and shear acting to distort soft tissues in a supine position, thereby reducing the risk of heel ulcers. Introducing the novel theoretical FEAE formulation, new laboratory methods to quantify the FEAE and a review of relevant clinical studies, this research underlines the importance of the FEAE in protecting the heels of at-risk patients. The work builds on a decade of research published by our group in analysing and evaluating dressing designs for pressure ulcer prevention and will be useful for clinicians, manufacturers, regulators and reimbursing bodies in assessing the effectiveness of dressings indicated or considered for prophylactic use.

A Finite Element Analysis Study of Edentulous Model with Complete Denture to Simulate Masticatory Movement.

The purposes of this study are to establish and validate a finite element (FE) model using finite element analysis methods and to identify optimal loading conditions to simulate masticatory movement. A three-dimensional FE model of the maxillary and mandibular cortical bone, cancellous bone, and gingiva was constructed based on edentulous cone-beam-computed tomography data. Dental computer-aided design software was used to design the denture base and artificial teeth to produce a complete denture. Mesh convergence was performed to derive the optimal mesh size, and validation was conducted through comparison with mechanical test results. The mandible was rotated step-by-step to induce movements similar to actual mastication. Results showed that there was less than a 6% difference between the mechanical test and the alveolar bone-complete denture. It opened 10° as set in the first stage, confirming that the mouth closed 7° in the second stage. Occlusal contact occurred between the upper and lower artificial teeth as the mouth closed the remaining angle of 3° in the third stage while activating the masseter muscle. These results indicate that the FE model and masticatory loading conditions developed in this study can be applied to analyze biomechanical effects according to the wearing of dentures with various design elements applied.

Corrective Efficacy of Calcaneal Lengthening Osteotomy for Planovalgus Deformity in Cerebral Palsy Patients.

Introduction Planovalgus deformity is common in children with spastic cerebral palsy (CP), particularly spastic diplegia and spastic quadriplegia. It results from muscle imbalance over the immature foot skeleton, leading to hindfoot valgus, forefoot abduction, and joint subluxation. Surgical interventions, like calcaneal lengthening osteotomy (CLO), are frequently employed to correct this deformity, but objective guidelines for its use in CP patients are lacking. Material and methods This retrospective cohort study examined the efficacy of CLO in correcting plano valgus deformity in pediatric CP patients at the Pediatric Orthopedic Unit of Christian Medical College (CMC) in Vellore, India. Data from patient records and radiographs were collected, including demographics, pre- and postoperative angles, and surgical details. Statistical analysis was performed to assess changes in angles and associations with various factors. Results After the surgery, there was a notable enhancement in the calcaneal pitch, lateral talo-first metatarsal angle, and naviculocuboid overlap, as shown by the CLO results. However, tibiocalcaneal angles did not show significant changes. Associations were observed between age, Gross Motor Function Classification System (GMFCS) level, additional surgeries, and postoperative angle corrections. Conclusion CLO shows promise in correcting plano valgus deformity, with age, GMFCS level, and comorbidities influencing outcomes. Long-term follow-up is crucial to monitor correction durability. Specific radiographic angles provide insights into CLO's biomechanical effects, but study limitations warrant caution in interpretation. CLO effectively corrects plano valgus deformity in pediatric CP patients, with age, GMFCS level, and comorbidities influencing outcomes. Long-term follow-up and further research are needed to optimize management strategies and enhance understanding of surgical outcomes.

Biomechanical Effects of Seizures on Cerebral Dynamics and Brain Stress.

Epilepsy is one of the most common neurological disorders globally, affecting about 50 million people, with nearly 80% of those affected residing in low- and middle-income countries. It is characterized by recurrent seizures that result from abnormal electrical brain activity, with seizures varying widely in manifestation. The exploration of the biomechanical effects that seizures have on brain dynamics and stress levels is relevant for the development of more effective treatments and protective strategies. This study uses a blend of experimental data and computational simulations to assess the brain's physical response during seizures, particularly focusing on the behavior of cerebrospinal fluid and the resulting mechanical stresses on different brain regions. Notable findings show increases in stress, predominantly in the posterior gyri and brainstem, during seizures and an evidence of brain displacement relative to the skull. These observations suggest a dynamic and complex interaction between the brain and skull, with maximum shear stress regions demonstrating the limited yet essential protective role of the CSF. By providing a deeper understanding of the mechanical changes occurring during seizures, this research supports the goal of advancing diagnostic tools, informing more targeted treatment interventions, and guiding the creation of customized therapeutic strategies to enhance neurological care and protect against the adverse effects of seizures.

A Controlled Variable Study of the Biomechanical Properties of the Proximal Femur before and after Cancellous Bone Removal.

The biomechanical characteristics of proximal femoral trabeculae are closely related to the occurrence and treatment of proximal femoral fractures. Therefore, it is of great significance to study its biomechanical effects of cancellous bone in the proximal femur. This study examines the biomechanical effects of the cancellous bone in the proximal femur using a controlled variable method, which provide a foundation for further research into the mechanical properties of the proximal femur. Seventeen proximal femoral specimens were selected to scan by quantitative computed tomography (QCT), and the gray values of nine regions were measure to evaluated bone mineral density (BMD) using Mimics software. Then, an intact femur was fixed simulating unilateral standing position. Vertical compression experiments were then performed again after removing cancellous bone in the femoral head, femoral neck, and intertrochanteric region, and data were recorded. According to the controlled variable method, the femoral head, femoral neck, and intertrochanteric trabeculae were sequentially removed based on the axial loading of the intact femur, and the displacement and strain changes of the femur samples under axial loading were recorded. Gom software was used to measure and record displacement and strain maps of the femoral surface. There was a statistically significant difference in anteroposterior displacement of cancellous bone destruction in the proximal femur (p < 0.001). Proximal femoral bone mass explained 77.5% of the strength variation, in addition proximal femoral strength was mainly affected by bone mass at the level of the upper outer, lower inner, lower greater trochanter, and lesser trochanter of the femoral head. The normal stress conduction of the proximal femur was destroyed after removing cancellous bone, the stress was concentrated in the femoral head and lateral femoral neck, and the femoral head showed a tendency to subside after destroying cancellous bone. The trabecular removal significantly altered the strain distribution and biomechanical strength of the proximal femur, demonstrating an important role in supporting and transforming bending moment under the vertical load. In addition, the strength of the proximal femur mainly depends on the bone density of the femoral head and intertrochanteric region.

[Research progress on pathological mechanism and clinical correlation between medial meniscus posterior root tear and tibial rotation].

To summarize the current research progress on the concept, clinical presentation, diagnosis, biomechanical changes, and pathological mechanisms of the medial meniscus posterior root tear (MMPRT), and its clinical correlations with tibial rotation. The research literature on MMPRT and its relationship with tibial rotation at home and abroad in recent years was extensively consulted and summarized. MMPRT is a specific and common type of medial meniscus injury of the knee joint. The occurrence of posterior medial pumping pain events following low-energy trauma in patients provides important clues for the diagnosis of this injury, with MRI being the preferred imaging modality. The biomechanical effects generated by MMPRT are similar to those caused by total removal of the medial meniscus. And this injury is usually associated with tibial rotation. MMPRT induces pathological external rotation of the tibia, which can be restored by timely medial meniscus posterior root repair. Furthermore, changes in tibial rotation are related to the healing status after medial meniscus posterior root repair. MMPRT is closely related to tibial rotation. Understanding the biomechanics, pathological mechanisms, and clinical correlations between the two is of great significance for improving the diagnosis and treatment strategies.