Significant Difference In Force Research Articles

Parameter Study and Optimization of Static Performance for a Hybrid Cable-Stayed Suspension Bridge

The hybrid cable-stayed and suspension (HCSS) bridge is known for its stability and cost-effectiveness, with significant application potential. This study examined the static performance of an HCSS bridge with a 1440 m main span. A finite element model (FEM) was developed to assess key parameters, such as the span-to-rise ratio, cable-to-hanger ratio, pylon stiffness, steel–concrete interface, and cable stiffness. Through FEM analysis and parameter optimization using the zero-order and first-order optimization methods in an ANSYS module, key design variables were optimized. The results show that an inappropriate span-to-rise ratio negatively impacts mid-span girder forces, while increasing the cable-stayed area enhances the overall stiffness. Main cable stiffness plays a crucial role in load-bearing and deformation control. Significant force differences were observed between stay and hanger cables, with axial force in the main girder increasing from the side span to the pylon under dead load. Bending moments in the transition region varied widely under combined loads. Optimizing parameters, such as the span-to-rise and cable-to-hanger ratios, significantly improved the mechanical performance of HCSS bridges, offering valuable insights for future designs.

Assessment of Intraday Variations in Skin Indentation Resistance.

Information about the mechanical properties of skin and their changes with age and other conditions is important to help characterize skin physiology and pathological changes. One method to obtain this information is to measure the force required to indent the skin to a specified indentation depth (FORCE). This process measures the tissue's resistance to indentation or its compressibility and is related to the tissue's elastic modulus. Since such measurements are made in clinical and other settings at various times of day (TOD), it is useful to estimate the extent of intraday variations in FORCE that may be expected. This report focuses on this issue. FORCE was self-measured on the volar forearm, 5 cm distal to the antecubital fossa, every two hours from 08:00 to 24:00 hours on two consecutive days by 12 medical students (six females and six males) who were trained in the measurement process using an indentation device (SkinFibroMeter). Variability in FORCE versus TOD was analyzed using the nonparametric Friedman test and differences between genders by the nonparametric Wilcoxon test. Differences between the first day (day 1) and the second day (day 2) were tested at each TOD. The whole-body fat percentage (FAT%) and water percentage (H2O%) were determined for each participant via bioimpedance measurements at 50 KHz. The age and BMI of the combined group (mean ± SD) were 24.5 ± 1.5 years and 23.2 ± 3.3 kg/m2.The overall average FORCE (mean ± SD) for the day over the 16 hours was 84.1 ± 22.7 mN and for day 2, it was 83.4 ± 28.5 mN with no significant difference between day 1 and day 2. For females, the overall two-day average FORCE (mean ± SD) over the 16 hours was 81.8 ± 20.3 mN and for males, it was 85.7 ± 30.1 mN with no significant difference between them (p = 0.271). Overall, there was no statistically significant difference in FORCE among TOD (p = 0.568). FORCE was not correlated with either FAT%, HTO%, or BMI. The findings indicate no statistically significant variation in indentation force in females, males, or combined concerning the TODof the measurement or differences between consecutive days at corresponding times. This suggests that whether such measurements are done in a research setting or within a clinic, they can be done at various TODwith minimal expected variation for a given subject. However, an extension of these findings to persons with skin conditions or ages not herein evaluated must await further study.

Ex vivo biomechanical evaluation and comparison of lateral femoro-fabella ligament suture and lateral suture with bone anchor for cranial cruciate ligament repair in cats.

To compare the biomechanical properties of lateral femoro-fabella ligament suture (FFLS) and lateral suture with a bone anchor suture (BAS) for management of feline cranial cruciate ligament disease. 12 femurs from 6 mature cat cadavers. The samples were collected from April to June 2023. The specimens had an FFLS and, subsequently, BAS placed and were positioned into a biomechanical testing machine, preloaded from 5 N to 15 N for 100 cycles, and subsequently, a load to suture failure was applied. The displacement at 5 N and 15 N, the total precycle displacement (millimeters), the force at 3 mm displacement and at failure (newtons), the displacement at failure (millimeters), and the stiffness to failure (Newton:millimiter) were recorded. Nonparametric Wilcoxon signed-rank tests were used to compare data between the 2 groups. The displacement at 5 N and 15 N and the total precycle displacement were significantly higher in the FFLS group compared to the BAS group. Additionally, the FFLS group results showed less consistent displacement and marked variability. The force (newtons) at 3 mm displacement was higher in the BAS group. There was no significant difference in force and no significant difference in displacement at failure between the 2 groups. However, the stiffness to failure (N/mm) was significantly higher in the BAS group. BAS represented a more stable and reliable femur attachment for extracapsular suture in cats. To demonstrate the stability and reliability between BAS and FFLS and influence implant selection in the treatment of cranial cruciate ligament rupture in cats with evaluation of biomechanical properties.

Development of Improved Confined Compression Testing Setups for Use in Stress Relaxation Testing of Viscoelastic Biomaterials.

The development of cell-based biomaterial alternatives holds significant promise in tissue engineering applications, but it requires accurate mechanical assessment. Herein, we present the development of a novel 3D-printed confined compression apparatus, fabricated using clear resin, designed to cater to the unique demands of biomaterial developers. Our objective was to enhance the precision of force measurements and improve sample visibility during compression testing. We compared the performance of our innovative 3D-printed confined compression setup to a conventional setup by performing stress relaxation testing on hydrogels with variable degrees of crosslinking. We assessed equilibrium force, aggregate modulus, and peak force. This study demonstrates that our revised setup can capture a larger range of force values while simultaneously improving accuracy. We were able to detect significant differences in force and aggregate modulus measurements of hydrogels with variable degrees of crosslinking using our revised setup, whereas these were indistinguishable with the convectional apparatus. Further, by incorporating a clear resin in the fabrication of the compression chamber, we improved sample visibility, thus enabling real-time monitoring and informed assessment of biomaterial behavior under compressive testing.

Efeitos do treinamento muscular do assoalho pélvico versus Ginástica Abdominal Hipopressiva (GAH) na incontinência urinária de esforço de mulheres climatéricas: ensaio clínico randomizado

ABSTRACT Pelvic floor muscle training (PFMT) is recommended as first-line treatment for stress urinary incontinence (SUI) in women (scientific evidence level 1). Currently, hypopressive abdominal gymnastics (HAG) has been used in clinical practice without evidence for this purpose. To verify the superiority of an experimental treatment in relation to a positive control (gold standard) for the treatment of SUI and PFM function in climacteric women. A non-inferiority clinical trial was conducted with 31 climacteric women with SUI who were sexually active. They were allocated into two groups: 16 in the PFMT group and 15 in the HAG group. Both groups received 26 sessions twice per week and individual care. All participants were assessed twice, at the beginning and at the end of interventions. The primary outcome was assessed using the International Consultation on Incontinence Questionnaire - Short Form (ICIQ-SF) and the secondary were given by PFM function assessed via bidigital palpation. The methods used to analyze the results were the two-way repeated measures analysis of variance (ANOVA), followed by the Tukey post-hoc test, when necessary. PFMT was better in improving SUI in the primary outcome (p=0.01). The groups showed no significant difference in force of contraction, time of sustained PFM, and fast and slow repetitions at the time of analysis. Regarding the symptoms of SUI, PFMT performed better than HAG.

Biomechanical comparison of open Bankart repair vs. conjoint tendon transfer in a 10% anterior glenoid bone loss shoulder instability model

The treatment of shoulder instability in patients with subcritical glenoid bone loss poses a difficult problem for surgeons as new evidence supports a higher failure rate when a standard arthroscopic Bankart repair is used. The purpose of this study was to compare a conjoint tendon transfer (soft-tissue Bristow) to an open Bankart repair in a cadaveric instability model of 10% glenoid bone loss. Eight cadaveric shoulders were tested using a custom testing system that allows for a 6-degree-of-freedom positioning of the glenohumeral joint. The rotator cuff muscles were loaded to simulate physiologic muscle conditions. Four conditions were tested: (1) intact, (2) Bankart lesion with 10% bone loss, (3) conjoint tendon transfer, and (4) open Bankart repair. Range of motion, glenohumeral kinematics, and anterior-inferior translation at 60° of external rotation with 20 N, 30 N, and 40 N were measured in the scapular and coronal planes. Glenohumeral joint translational stiffness was calculated as the linear fit of the translational force-displacement curve. Force to anterior-inferior dislocation was also measured in the coronal plane. Repeated measures analysis of variance with a Bonferroni correction was used for statistical analysis. A Bankart lesion with 10% bone loss increased the range of motion in both the scapular (P=.001) and coronal planes (P=.001). The conjoint tendon transfer had a minimal effect on the range of motion (vs. intact P=.019, .002), but the Bankart repair decreased the range of motion to intact (P=.9, .4). There was a significant decrease in glenohumeral joint translational stiffness for the Bankart lesion compared with intact in the coronal plane (P=.021). The conjoint tendon transfer significantly increased stiffness in the scapular plane (P=.034), and the Bankart repair increased stiffness in the coronal plane (P=.037) compared with the Bankart lesion. The conjoint tendon transfer shifted the humeral head posteriorly at 60° and 90° of external rotation in the scapular plane. The Bankart repair shifted the head posteriorly in maximum external rotation in the coronal plane. There was no significant difference in force to dislocation between the Bankart repair (75.8±6.6 N) and the conjoint tendon transfer (66.5±4.4 N) (P=.151). In the setting of subcritical bone loss, both the open Bankart repair and conjoint tendon transfer are biomechanically viable options for the treatment of anterior shoulder instability; further studies are needed to extrapolate these data to the clinical setting.

PD30-01 USING MACHINE LEARNING TO CLASSIFY PROCEDURE-SPECIFIC SURGICAL EXPERIENCE BASED ON SURGICAL GESTURE RECOGNITION IN A RADICAL PROSTATECTOMY SIMULATION

You have accessJournal of UrologyCME1 Apr 2023PD30-01 USING MACHINE LEARNING TO CLASSIFY PROCEDURE-SPECIFIC SURGICAL EXPERIENCE BASED ON SURGICAL GESTURE RECOGNITION IN A RADICAL PROSTATECTOMY SIMULATION Nathan Schuler, Lauren Shepard, Tyler Holler, Patrick Saba, and Ahmed Ghazi Nathan SchulerNathan Schuler More articles by this author , Lauren ShepardLauren Shepard More articles by this author , Tyler HollerTyler Holler More articles by this author , Patrick SabaPatrick Saba More articles by this author , and Ahmed GhaziAhmed Ghazi More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003316.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Effectiveness of nerve sparing robot assisted radical prostatectomy (NS-RARP) is mainly based on recovery of postoperative erectile function. Previously, robotic kinematic data differentiated surgical expertise in suturing tasks and predicted continence rates. Using a validated realistic NS-RARP simulation with embedded sensors measuring torque on neurovascular bundles (NVB), our objective was to apply machine learning algorithms to classify surgical experience based on pure surgical gesture data inputs. METHODS: 50 certified urologists with average robotic case volumes (RV) of 1206 (range 100 - >5000) completed surveys and a NS-RARP simulation, during which video and force sensor data were collected. Videos were annotated for ten approved individual surgical gestures (e.g., cut, traction etc.) and aggregated based on instrument used and combinations of multiple gestures. Total force, average force, and number of force peak events were calculated. With a total of 33 inputs, output included total/NS-RARP case volume and NVB force data. Data was fit to a Gaussian Mixture model, then separated based on gesture utilization patterns. Tukey’s HSD test was used to determine significance in inter-group comparisons of RV and force metrics. RESULTS: Participants were clustered into 3 groupings based on mean total RV: 14 Super-Users (SU) (2221), 14 High Volume (HV) (1017), and 5 Low Volume (LV) (110) urologists (Figure 1). Significant differences were found between SU and HV for both Robotic case (p=0.03) and RARP volumes (p=0.008). Gesture pattern comparisons showed significant differences between SU vs HV and HV v LV in 64% and 30% of gesture inputs respectively. Force sensor comparisons showed significant differences in Total Force and Force Peak events between SU vs LV (p=0.014; p=0.021) and HV vs LV (p=0.021; p=0.046) groups. No significant differences in forces between SU and HV were found. CONCLUSIONS: This machine learning algorithm successfully categorized surgical experience into caseload and force applied, based solely on gesture inputs within a realistic simulated NS-RARP task. Differences in gestures differentiated HV from SU urologists, alluding to potential for targeted areas of improvement in gesture patterns, even for HV surgeons. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e830 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Nathan Schuler More articles by this author Lauren Shepard More articles by this author Tyler Holler More articles by this author Patrick Saba More articles by this author Ahmed Ghazi More articles by this author Expand All Advertisement PDF downloadLoading ...

Clear aligner orthodontic force and conformity during lateral expansion

ABSTRACT Purpose: This study aimed to find the clear aligner form which buccal tipping is less likely to occur by experimentally comparing the marginal type of the aligners with the orthodontic force and conformity (flotation) on the first molars during lateral expansion. Materials and methods: Four different marginal types (conventional aligners with no palatal coverage, partial palatal coverage [with or without 2.0 mm buccal extension], and complete palatal coverage) and three levels of lateral expansion (no expansion, 0.25-mm expansion, and 0.50-mm expansion) were used. The force applied to the first molar was measured by attaching a pressure sensor to the palatal side of the left first molar on a modelled maxillary constricted dental arch. The conformity (flotation) was measured by micro-CT with each aligner attached to the model. Results: Conventional aligners showed no significant difference in force at 0.25-mm or 0.50-mm expansion, but significant flotation at the midpoint and cervical side. The force of all three types of palatal coverage aligners increased significantly (p < 0.01) with increasing expansion and showed less flotation (p < 0.01) compared to the conventional type. Complete palatal coverage aligners had little flotation at 0.25-mm expansion and no expansion. Conclusion: Conventional aligners should have greater buccal tipping of the molars due to increased flotation with expansion. Complete palatal coverage aligners with 0.25-mm expansion had the best conformity, suggesting that they may prevent unplanned buccal tipping of the molars and allow lateral expansion to occur as intended.

Is there an increased risk for subtrochanteric stress fracture with the Femoral Neck System versus multiple cannulated screws fixation?

PurposeThis study sought to compare the risk of subtrochanteric stress-riser fractures and biomechanical stability of the Femoral Neck System (FNS) versus multiple screw fixation (MSF). MethodsEight paired cadaveric femurs were randomly assigned to FNS or MSF. Physiologic load mimicking single leg stance at the subtrochanteric region was applied to the constructs. ResultsNo constructs failed in the subtrochanteric region during loading. There was no significant difference in force (P = 0.364) or loading cycles (P = 0.348) between groups. ConclusionFNS constructs were not associated with an increased incidence of iatrogenic subtrochanteric fractures or biomechanical stability versus MSF.

Experimental Evaluation of the Elson Test Efficiency Following Central Slip Injury

PurposeThe purpose of this article is to explore the amount of work, quantitated by flexion and extension cycles, that is needed to obtain a positive Elson test following a central slip injury. MethodsThirteen frozen cadaveric fingers from individuals with an average age of 79.6 years were used. Testing was performed by imposing sinusoidal displacement of the 2 tendons, with loads ranging from 30 N to 2 N at 1 Hz. Following transection to the central slip, each finger was cycled 1,000 times using the same protocol adopted for the control. Following 100, 200, 300, and 1,000 cycles, we measured the extension angles of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints from the flexed position and the distance between landmarks of the extensor apparatus and simulated an Elson test. ResultsIn both the fingers, the range of motion of the metacarpophalangeal and distal interphalangeal joints measured in the controls remained unchanged, whereas the range of motion of the proximal interphalangeal joint was significantly reduced immediately after central slip transection. Combining both ring and middle fingers, for a displacement of 5 mm, the force measured in the control (1.05 ± 0.69 N) increased to the value of 2.36 ± 0.97 N at the 1,000th cycle. Although the middle finger has shown a significant difference in force at 100 cycles following central slip transection, 200 cycles were needed to observe a difference on the ring finger. ConclusionsIn controlled conditions, there is a variation in resistance to flexion of the distal interphalangeal joint. However, the amplitude of the forces is so small that they are likely imperceptible clinically. Delayed testing should be considered to increase the sensitivity of the test or in patients experiencing pain. Type of study/level of evidenceDiagnostic V.

27 Within- and between-session reliability of the Tekscan™ Hoof System with a glue-on shoe

A current focus in equine research is to utilize technology which minimizes the subjective nature of gait and lameness analysis. One such technology is the Tekscan Hoof System, which can measure the force and area of a step while an animal is in motion. The objective of this study was to determine the reliability of the Tekscan Hoof System to measure force and area in 2 different sessions, and recordings within each of those sessions. Four mature Standardbred geldings from the MSU Horse Teaching and Research Center were exercised with Tekscan Hoof System sensors secured by a glue-on shoe (Sound Horse Technologies) to their front hooves. Horses were each exercised in AM and PM sessions. In both the AM and PM sessions, horses walked for 3 recordings of at least 10 steps and trotted for 3 recordings of at least 10 steps. The F-Scan research software (version 6.85) was utilized to analyze and export step data. Session differences were calculated with a MIXED procedure in SAS 9.4, with fixed effects of recording nested within session, gait, horse, and leg. Within- and between-session reliability was assessed in SPSS using Intraclass Correlation Coefficients (ICC(3,k)) and 95% confidence intervals (CI). Force and area in the AM recordings were 30% and 23% (respectively) greater than the PM recordings ( P < 0.0001). Between AM and PM sessions, ICC for the walk had good to excellent reliability for force (0.959; 0.797 – 0.992) and moderate to excellent reliability for area (0.907; 0.537 – 0.981); reliability at the trot was excellent for force (0.982, 0.911–0.996) and poor to excellent for area (0.897; 0.486–0.979). Within the AM and PM sessions, there were no significant differences in force or area between recordings (all P < 0.40). Within the AM and PM sessions, reliability was good to excellent at both walk and trot for force (ICCs ≥0.962; 0.817 – 0.999) and area (ICCs ≥0.942; 0.711 – 0.998). Force and area measurements were lower in the PM session, potentially due to sensel failure caused by exposure to moisture and organic materials. This phenomenon of decreased force and area was not seen within the AM or PM sessions, suggesting that prolonged exposure to moisture and organic matter between sessions may have caused decreased reliability. The Tekscan Hoof System has been found to have good to excellent reliability within a session when used with a glue-on shoe, but caution should be taken when comparing between sessions given the large 95% CI. When used in a research or clinical setting, recordings should be taken within one session for improved reliability.

A comparison of methods used to secure pediatric endotracheal tubes using a live human dermal model.

Endotracheal intubation is a common lifesaving procedure. An in situ endotracheal tube (ETT) must be secured in position to avoid displacement and potentially life-threatening complications. Adhesive tapes form the most common intraoperative ETT stabilization methods. Limited published data are available to guide the clinical decision regarding ETT taping method. We performed an interventional study aiming to establish which of many commonly employed ETT tape/supplementary adhesive methods provides the most resistance to ETT distraction. An experiment was undertaken to measure the force required to distract an ETT secured to a live dermal model with 24 different ETT securing methods comprising six types of tape alone and in combination with one of three supplementary adhesives. The primary measurement was the peak force (Newtons) required to distract a secured ETT 3 cm. A total of 1,164 measurements were made. The mean force required to distract the ETT ranged from 7.8 to 21.8 Newtons. The combination of Cloth Adhesive™ + Mastisol® had the greatest observed mean distraction force, as well as the greatest estimated lower and upper confidence limits. There are significant differences in force required to distract an ETT based on taping methods.

Modeling statin myopathy in a human skeletal muscle microphysiological system.

Statins are used to lower cholesterol and prevent cardiovascular disease. Musculoskeletal side effects known as statin associated musculoskeletal symptoms (SAMS), are reported in up to 10% of statin users, necessitating statin therapy interruption and increasing cardiovascular disease risk. We tested the hypothesis that, when exposed to statins ex vivo, engineered human skeletal myobundles derived from individuals with (n = 10) or without (n = 14) SAMS and elevated creatine-kinase levels exhibit statin-dependent muscle defects. Myoblasts were derived from muscle biopsies of individuals (median age range of 62–64) with hyperlipidemia with (n = 10) or without (n = 14) SAMS. Myobundles formed from myoblasts were cultured with growth media for 4 days, low amino acid differentiation media for 4 days, then dosed with 0 and 5μM of statins for 5 days. Tetanus forces were subsequently measured. To model the change of tetanus forces among clinical covariates, a mixed effect model with fixed effects being donor type, statin concentration, statin type and their two way interactions (donor type*statin concentration and donor type* statin type) and the random effect being subject ID was applied. The results indicate that statin exposure significantly contributed to decrease in force (P<0.001) and the variability in data (R2C [R square conditional] = 0.62). We found no significant differences in force between myobundles from patients with/without SAMS, many of whom had chronic diseases. Immunofluorescence quantification revealed a positive correlation between the number of straited muscle fibers and tetanus force (R2 = 0.81,P = 0.015) and negative correlation between number of fragmented muscle fibers and tetanus force (R2 = 0.482,P = 0.051) with no differences between donors with or without SAMS. There is also a correlation between statin exposure and presence of striated fibers (R2 = 0.833, P = 0.047). In patient-derived myobundles, statin exposure results in myotoxicity disrupting SAA organization and reducing force. We were unable to identify differences in ex vivo statin myotoxicity in this system. The results suggest that it is unlikely that there is inherent susceptibility to or persistent effects of statin myopathy using patient-derived myobundles.

Comparison of force delivery of thermally activated aesthetic and non-aesthetic Ni-Ti wires: An in-vitro study

The present study aimed to compare the force of aesthetic wires and their non-aesthetic equivalents from two commercial brands at different displacement points, during the unloading phase at 36°C. Forty samples (n=10) were assessed, which were presented in two groups of aesthetic wires and two groups of non-aesthetic wires from the brands GAC® (Dentsply GAC® International, NY, USA) and Aditek®(Cravinhos, SP, Brazil), with 0.016-inch gauge. The orthodontic wires were maintained at a temperature of 36°C throughout the experiment and they were subjected to the three-point bending test at a speed of 1mm/min. The unloading values were recorded as 0.5, 1.5, and 2.5mm of displacement. The data were subjected to Student's t-test and unequal variance t test, at 5% significance level. During the unloading phase, the mean force was significantly higher for aesthetic wires than non-aesthetic ones, in the deflection of 2.5mm, presenting values means of 2.25N (P=.0213). In deflections of 0.5mm and 1.5mm, the orthodontic archwires did not show significant differences in force between the thermally activated wires with aesthetic coating and their non-aesthetic equivalents (P≥0.05). It is concluded that during the unloading phase at a temperature of 36°C, the orthodontic archwires analyzed did not show significant difference in force between thermally activated wires with aesthetic coating and their non-aesthetic equivalents at most displacement points analysed, except for the deflection of 2.5mm, which showed higher values.

Force Metrics and Suspension Times for Microlaryngoscopy Procedures

To determine the difference in force metrics measured by the laryngeal force sensor for various suspension microlaryngoscopy (SML) procedures and their perioperative narcotic requirements. Prospective observational study. Academic tertiary center. The laryngeal force sensoris a force sensor designed for SML procedures. Prospectively enrolled patients had dynamic recordings of maximum force, average force, suspension time, and total impulse. Procedures were grouped into excision of striking zone lesions, nonstriking zone lesions, endoscopic cancer surgery with margin control, and airway dilation. Narcotic administration in the intraoperative period and postanesthesia care unit was also recorded and converted into IV morphine equivalents. Surgeons were blinded to the force recordings during surgery to prevent operator bias. In total, 110 patients completed the study. There was no significant difference in average force across different procedures, however, a significant difference was seen for maximum force (P=0.025), suspension time (P < 0.001), and total impulse (P=0.002). The highest values were seen for endoscopic cancer surgeries with margin control with a mean maximum force of 49.4 lbf (95%CI, 37.1-61.7), mean suspension time of 60.2 minutes (95%CI, 40.5-79.9), and mean total impulse of 31.3 ton*s (95%CI, 15.2-47.3). A significant difference (P < 0.01) in perioperative narcotic requirements was also seen, with endoscopic cancer surgery cases having the highest requirements at 27.6 mg of ME (95%CI, 16.1-39.2 mg). Significant differences in force metrics exist between various SML procedures. Endoscopic cancer surgery is associated with higher force metrics and perioperative narcotic requirements.

Optimized mitral annuloplasty ring design reduces loading in the posterior annulus

ObjectiveThe study objective was to develop a novel annuloplasty ring with regional flexibility and assess its suture force dynamics in healthy ovine subjects compared with fully rigid or fully flexible rings. MethodsMaterially heterogeneous rings were created with rigid anterior and posterior, and flexible commissural segments. These rings were created to match the geometry of the Profile 3D ring (Medtronic, Minneapolis, Minn). Each ring was instrumented with 10 force transducers to measure cyclic suture forces (FC) and undersized annuloplasty was performed in 6 healthy ovine subjects. Each FC was recorded and examined for cardiac cycles reaching a maximum left ventricular pressure of 100, 125, and 150 mm Hg. FC was compared with previously reported values from fully rigid Profile 3D and fully flexible prototype rings. ResultsRelative to the fully rigid ring, the heterogeneous ring exhibited 48% reduction in FC at its commissural (rigid vs heterogeneous: 1.80 ± 0.94 N vs 0.95 ± 0.52 N; P < .001) and 32% reduction in posterior (1.90 ± 0.92 N vs 1.29 ± 0.91 N; P < .001) regions, but not in its anterior region (2.45 ± 1.21 N vs 2.23 ± 1.22 N; P = .279). Relative to the fully flexible ring, the heterogeneous ring exhibited no significant differences in FC in any region. ConclusionsThe reduced FC of the heterogeneous ring relative to the fully rigid ring suggests a promising approach to reduce suture loading while preserving the annular remodeling capability of fully rigid rings. Future studies in diseased subjects are necessary to explore repair effectiveness of this ring.

Assessment of Hedgehog Signaling Pathway Activation for Craniofacial Bone Regeneration in a Critical-Sized Rat Mandibular Defect.

Osseous craniofacial defects are currently reconstructed with bone grafting, rigid fixation, free tissue transfer, and/or recombinant human bone morphogenetic protein 2. Although these treatment options often have good outcomes, they are associated with substantial morbidity, and many patients are not candidates for free tissue transfer. To assess whether polysaccharide-based scaffold (PS) constructs that are cross-linked with smoothened agonist (SAG), vascular endothelial growth factor (VEGF), and bone morphogenetic protein 6 (BMP-6) would substantially increase bone regeneration. This animal model study was conducted at the University of Virginia School of Medicine Cui Laboratory from March 1, 2017, to June 30, 2017. Thirty-three 10-week-old female Lewis rats were acquired for the study. Bilateral nonsegmental critical-sized defects were created in the angle of rat mandibles. The defects were either left untreated or filled with 1 of the 9 PSs. The rats were killed after 8 weeks, and bone regeneration was evaluated using microcomputed tomographic imaging and mechanical testing. Analysis of variance testing was used to compare the treatment groups. Blinded analysis and computer analysis of the microcomputed tomographic images were used to assess bone regeneration. In the 33 female Lewis rats, minimal healing was observed in the untreated mandibles. Addition of SAG was associated with increases in bone regeneration and bone density in all treatment groups, and maximum bone healing was seen in the group with BMP-6, VEGF, and SAG cross-linked to PS. For each of the 5 no scaffold group vs BMP-6, VEGF, and SAG cross-linked to PS group comparisons, mean defect bone regeneration was 4.14% (95% CI, 0.94%-7.33%) vs 66.19% (95% CI, 54.47%-77.90%); mean bone volume, 14.52 mm3 (95% CI, 13.07-15.97 mm3) vs 20.87 mm3 (95% CI, 14.73- 27.01 mm3); mean bone surface, 68.97 mm2 (95% CI, 60.08-77.85 mm2) vs 96.77 mm2 (95% CI, 76.11-117.43 mm2); mean ratio of bone volume to total volume, 0.11 (95% CI, 0.10-0.11) vs 0.15 (95% CI, 0.10-0.19); and mean connectivity density 0.03 (95% CI, 0.02-0.05) vs 0.32 (95% CI, 0.25-0.38). On mechanical testing, mandibles with untreated defects broke with less force than control mandibles in which no defect was made, although this force did not reach statistical significance. No significant difference in force to fracture was observed among the treatment groups. In this rat model study, activation of the hedgehog signaling pathway using smoothened agonist was associated with increased craniofacial bone regeneration compared with growth factors alone, including US Food and Drug Administration-approved recombinant human bone morphogenetic protein 2. Pharmaceuticals that target this pathway may offer a new reconstructive option for bony craniofacial defects as well as nonunion and delayed healing fractures. NA.

The effect of dominant first dorsal interosseous fatigue on the force production of a contralateral homologous and heterologous muscle.

Crossover and nonlocal muscle fatigue (NLMF) has generally focused on large muscle groups. It is unclear if fatigue of a small muscle can result in NLMF of a larger muscle. The purpose of the present study was to examine the effect of small muscle (first dorsal interosseous; FDI) fatigue on the force and activation of contralateral homologous and larger heterologous muscles (biceps brachii; BB). Fifteen right-handed male subjects performed 3 pre-test index finger abduction or elbow flexion maximum voluntary isometric contractions (MVICs) on the nondominant side. Subsequently, they performed two 100-s index finger abduction MVICs on the dominant side (experimental (fatigue) group) or rested for 5 min (control group). Afterwards, a single MVIC and a 12-repetition MVIC fatiguing protocol were completed with index finger abduction or elbow flexion on the nondominant side. Force and electromyography (EMG) were measured from both sides. The force and EMG (median frequency; MDF) of nonexercised index finger abductors (IFA)/FDI and elbow flexors (EF)/BB significantly decreased after the fatiguing protocol. Compared with the control condition, the nonexercised IFA (12.5% and 5.7%) had significantly greater force and MDF fatigue indexes than the EF (5.2% and 1.7%). There were no significant force differences with the single MVIC test between conditions. The small muscle fatiguing protocol produced NLMF effects on both contralateral homologous and larger heterologous muscles, with the force decrements greater with the homologous muscle.

Evaluating the Femoral-Side Critical Corner in Posterior Cruciate Ligament Reconstruction: The Effect of Outside-In Versus Inside-Out Creation of Femoral Tunnels on Graft Contact Pressure in a Synthetic Knee Model

To characterize and compare the graft contact characteristics of outside-in (OI) and inside-out (IO) femoral tunnels during single-bundle reconstruction of the anterolateral bundle of the posterior cruciate ligament in a synthetic knee model. Femoral tunnels were separately made in 16 synthetic femora (8 OI and 8 IO). Achilles tendon allografts were fixed using suspensory fixation with a pressure sensor between the allograft and femoral tunnel. Grafts were cyclically loaded; force, contact area, contact pressure, and peak pressure at the aperture were measured. This process was repeated using the same allograft to assess the other tunnel angle in a separate specimen. IO specimens showed higher mean contact pressure at all loading cycles, with significance shown at 50N(P= .02). Peak pressure was also greater in IO specimens at all loading cycles and reached statistical significance at 100N(P= .04). IO specimens had a lower contact area at 150N(P= .04). No statistically significant differences in force were observed between the 2 groups. OI creation of the femoral tunnel for anterolateral bundle reconstruction of the posterior cruciate ligament resulted in decreased mean and peak contact pressures at the femoral aperture compared with IO tunnel creation at the specific trajectories and loading parameters tested in this synthetic femoral model. These biomechanical data suggest that OI creation of the femoral tunnel may help reduce invivo graft contact pressure at the femoral aperture. These data suggest that a tunnel drilled from OI may result in less graft pressure at the femoral aperture, which may prevent graft elongation and optimize graft survival.

Comparison of mechanical properties of three orthodontic wires between levelled and unlevelled brackets: An in vitro study

Background: The objective of this study was to compare the mechanical properties of three orthodontic wires between levelled and unlevelled bracket using a three-point bending test. Methods: Three groups of ten Nickel titanium, Betatitanium and CuNiTi wire segments (0.017 × 0.025-in. diameter) were used. Two brackets were bonded to an acrylic jig with a 10-mm interbracket distance. Deflection test was done in two scenarios, one with aligned brackets and other with 2-mm horizontal displacement of the brackets to simulate malaligned teeth. Forces of loading and unloading of the wires during both tests were compared by an analysis of variance (ANOVA) tests. Results: The difference of LDR between levelled and unlevelled brackets during loading in NiTi wire was 0.1 N, Beta-titanium wire 0.2 N and CuNiTi wire was 1.5 N. The difference of LDR between levelled and unlevelled brackets during unloading in NiTi wire was 0.2 N, Betatitanium wire was 0.3 N and CuNiTi wire is 0.5 N. Conclusions: The study showed some significant differences in forces generated during loading and unloading among the three different types of wires tested. During both the scenarios only CuNiTi wire showed significant difference. Betatitanium wire exhibited highest force followed by NiTi and CuNiTi. Keywords: NiTi, Beta-titanium, CuNiTi wires, Three-point bending test, Load deflection rate (LDR), Newtons (N)