Development and Multi-Site Assessment of a Novel Shoulder Motion Joint Simulator

Background: Multiple biomechanical shoulder simulators have been described in the literature, with a trend toward increasing complexity to better simulate clinical scenarios. Our objective was to develop an advanced, novel shoulder joint simulator and compare outcomes at two separate institutions, for a typical shoulder joint motion simulation. Methods: Identical shoulder simulators were developed & deployed at both institutions. Eight cadaveric upper extremities were tested by simulating actively controlled, arm elevation in the plane of the scapula for two sequential test conditions (intact and non-destructive simulated cuff-tear), each repeated for a total of five trials. Muscle forces and joint translations were recorded for both conditions. The intact condition was repeated following simulated cuff-tear to assess effect of testing order. Statistical analyses were aimed at assessing repeatability and reproducibility of results within specimens, between specimens, and between institutions. Results: The highest average forces were observed for the middle deltoid (233N or 32.5% body weight), followed by infraspinatus (99.0N), and posterior deltoid (93.7N) muscles. Differentiation between test conditions was unhindered by variability between repeated trials. Data from testing repeated over time, and between the two institutions were not significantly different. Conclusions: The novel shoulder simulator produced repeatable results with low trial-to-trial variation and outcomes were comparable between the two institutions. The results demonstrated a consistent response in muscle forces and humeral translation for the simulated rotator cuff tear condition. Such advanced shoulder simulators could thus be used for evaluating and optimizing surgical interventions and implant strategies.

Loosening of Posteromedial Meniscal Root Repairs Affects Knee Mechanics: A Finite Element Study

Meniscal root repairs are susceptible to unrecoverable loosening that may displace the meniscus from the initial position reduced during surgery. Despite this, the effects of a loosened meniscal root repair on knee mechanics are unknown. We hypothesized that anatomic root repairs without loosening would restore knee mechanics to the intact condition better than loosened anatomic root repairs, but that loosened repairs would restore mechanics better than untreated meniscal root tears. Finite element knee models were used to evaluate changes in cartilage and meniscus mechanics due to repair loosening. The mechanical response from loosened anatomic root repairs was compared to anatomic repairs without loosening and untreated root tears. All conditions were evaluated at three flexion angles, 0°, 30°, and 60°, and a compressive force of 1,000 N to simulate return-to-activity loading. The two-simple-suture method was represented within the models to simulate posteromedial meniscal root repairs and repair loosening was derived from previous biomechanical experimental data. Loosening decreased hoop stresses throughout the meniscus, increased posterior extrusion, and shifted loading through the meniscus-cartilage region to the cartilage-cartilage region compared to the anatomic root repair without loosening. Despite differences between repairs and loosened repairs, the changes from loosened repairs more closely resembled the anatomic repair without loosening than the untreated root repair condition. Therefore, root repairs are susceptible to loosening that will prevent a successful initial repair from remaining in the intended position and will alter mechanics, although repairs that loosen appear better than leaving tears untreated.

Influence of Lumbar Lordosis on Posterior Rod Strain in Long-Segment Construct During Biomechanical Loading: A Cadaveric Study

Objective: The lordotic shape of the lumbar spine differs substantially between individuals. Measuring and recording strain during spinal biomechanical tests is an effective method to infer stresses on spinal implants and predict failure mechanisms. The geometry of the spine may have a significant effect on the resultant force distribution, thereby directly affecting rod strain.Methods: Seven fresh-frozen cadaveric specimens (T12-sacrum) underwent standard (7.5 Nm) nondestructive sagittal plane tests: flexion and extension. The conditions tested were intact and pedicle screws and rods (PSR) at L1-sacrum. The posterior right rod was instrumented with strain gauges between L3–4 (index level) and the L5–S1 pedicle screw. All specimens underwent lateral radiographs before testing. Lordotic angles encompassing different levels (L5–S1, L4–S1, L3–S1, L2–S1, and L1–S1) were measured and compared with rod strain. Data were analyzed using Pearson correlation analyses.Results: Strong positive correlations were observed between lordosis and posterior rod strain across different conditions. The L3–S1 lordotic angle in the unloaded intact condition correlated with peak rod strain at L3–4 with PSR during flexion (R = 0.76, p = 0.04). The same angle in the unloaded PSR condition correlated with peak strain in the PSR condition during extension (R = -0.79, p = 0.04). The unloaded intact L2–S1 lordotic angle was significantly correlated with rod strain at L3–4 in the PSR condition during flexion (R = 0.85, p = 0.02) and extension (R = -0.85, p = 0.02) and with rod strain at L5–S1 in the PSR condition during flexion (R = 0.84, p = 0.04).Conclusion: Lordosis measured on intact and instrumented conditions has strong positive correlations with posterior rod strain in cadaveric testing.

Effect of a Flexor Digitorum Superficialis Hemitenodesis on Reducing Volar Plate Strains for Swan Neck Deformities

Background Flexor digitorum superficialis (FDS) hemitenodesis is a common procedure to treat swan neck deformity (SND). We hypothesize that this surgical technique is a biomechanically effective way to reduce strain in the volar plate at the proximal interphalangeal joint (PIPJ). Methods Fifteen digits from 5 cadaveric specimens were tested using a novel in vitro active finger motion simulator under 4 finger conditions: intact, SND, FDS hemitenodesis, and FDS hemitenodesis with distal interphalangeal (DIP) joint fusion. Tensile loads in FDS and flexor digitorum profundus (FDP) and joint ranges of motion were measured by electromagnetic tracking. In addition, strain gauges were inserted under the volar plate to measure strain during PIPJ hyperextension. Results were analyzed using 1-way repeated-measures analysis of variance tests. Results The SND condition increased volar plate strain by 176% ± 25% ( P < .001) compared with the intact condition. The FDS hemitenodesis repair relieved more than 50% of the SND strain, restoring it to within no statistical difference from intact. The DIP fusion further reduced strain with no further statistical significance. At full flexion, FDS and FDP tendon loads diverged as a function of the test condition ( P < .001). With the FDS hemitenodesis, the FDP load increased by 2.1 ± 1.5 N from the SND condition ( P < .001), whereas the FDS load decreased by 1.3 ± 1.3 N ( P = .012). Conclusion The FDS hemitenodesis repair restored strains to within 3.0 milli-strain of the intact condition with no significant difference. Application of DIP fusion did not further protect the PIPJ from increased hyperextension and further exacerbated the imbalance of flexor tendon loads.

Temporal fine structure influences voicing confusions for consonant identification in multi-talker babble

To understand the mechanisms of speech perception in everyday listening environments, it is important to elucidate the relative contributions of different acoustics cues in transmitting phonetic content. Previous studies suggest that the energy envelopes of speech convey most speech content, while the temporal fine structure (TFS) can aid in segregating target speech from background noise. Despite the vast literature on TFS and speech intelligibility, the role of TFS in conveying additional speech content over what envelopes convey in complex acoustic scenes is poorly understood. The present study addresses this question using online psychophysical experiments to measure consonant identification in multi-talker babble for intelligibility-matched intact and 64-channel envelope-vocoded stimuli. Consonant confusion patterns revealed that listeners had a greater tendency in the vocoded (versus intact) condition to be biased towards reporting that they heard an unvoiced consonant, despite envelope and place cues being largely preserved. This result was replicated when babble instances were varied across independent experiments, suggesting that TFS conveys important voicing cues over what envelopes convey in multi-talker babble, a masker that is ubiquitous in everyday environments. This finding has implications for assistive listening devices that do not currently provide TFS cues, such as cochlear implants.

Intangible Conditions of Human Resources Factors in MSME Decade of Covid 19 in the Bandung City-West Java-Indonesia

The purpose of this study is to compensate for the intangible variables of the human resources of MSME actors in Bandung City, related to Employee Engagement and Attitude at the time of the COVID-19. Therefore, the intact condition of the two related variables is important for stakeholders such as the government and other related parties to understand and serve as a basis for policy and decision making, especially when the economy is exposed to COVID-19. The research method used is descriptive, verification and comparative. Data were tested using the validity test, reliability test, classical assumptions and data normality, and to test the level of contribution between variables and variable dimensions used correlation and termination tests. The data were obtained from the MSME economic actors in the city of Bandung total 45 samples. The city of Bandung was chosen as a place of research because the city of Bandung is known as a model city, culinary, education, creative industries as well as the city of culture and government of West Java. The results showed that the contribution, enthusiasm, pride of business people towards MSMEs was not supportive, lost trust and small. Only MSME players have employee engagement in the form of willingness. Attitudes or attitudes in the form of motives, traits and self-concepts are still strong for every MSME actor in Bandung City, and this condition is in line with the willingness dimension of employee engagement. Based on the results of the study, it can be concluded that the employee engagement of MSME actors in the city of Bandung is currently not good or has decreased, while the attitude at is still good.

Posterior Tibial Loading Results in Significant Increase of Peak Contact Pressure in the Patellofemoral Joint During Anterior Cruciate Ligament Reconstruction: A Cadaveric Study

Background: Inappropriate posterior tibial loading and initial graft tension during anterior cruciate ligament (ACL) reconstruction may cause altered patellofemoral joint (PFJ) contact mechanics, potentially resulting in pain and joint degeneration. Hypothesis: PFJ contact pressure would increase with the increases in posterior tibial loading and graft tension during ACL reconstruction. Study Design: Controlled laboratory study. Methods: Nine fresh-frozen, nonpaired human cadaveric knees were tested in a customized jig from 0° to 120° of knee flexion. First, the knee was tested in the ACL-intact state. Second, reconstruction of the ACLs using different posterior tibial loadings and graft tensions were performed. The posterior tibial loading was evaluated at 2 levels: 33.5 and 67 N. Graft tension was assessed at 3 levels: low tension (20 N), medium tension (60 N), and high tension (80 N). Maximum values of peak contact pressure in the medial and lateral patellar facets were compared between ACL-intact and ACL-reconstructed knees. The PFJ kinematics between ACL-intact knees and ACL-reconstructed knees were compared during knee flexion at 30°, 60°, 90°, and 120°. Results: Reconstruction of ACLs with both low and high posterior tibial loading resulted in significant increases of peak contact pressure in the medial (range of differences, 0.46-0.92 MPa; P < .05) and lateral (range of differences, 0.51-0.83 MPa; P < .05) PFJ compared with the ACL-intact condition. However, no significant differences in PFJ kinematics were identified between ACL-reconstructed knees and ACL-intact knees. In ACL-reconstructed knees, it was found that a high posterior tibial loading resulted in high peak contact pressure on the medial patellar side (range of differences, 0.37-0.46 MPa; P < .05). No significant difference in peak contact pressure was observed among the differing graft tensions. Conclusion: In this cadaveric model, ACL reconstruction resulted in significant increases of peak contact pressure in the PFJ facet when compared with the ACL-intact condition. A high posterior tibial loading can lead to high medial PFJ peak contact pressure. Graft tension was found to not significantly affect PFJ contact pressure during ACL reconstruction. Clinical Relevance: An excessive posterior tibial loading during ACL reconstruction resulted in increased PFJ contact pressures at time of surgery. These data suggest that a low posterior tibial loading might be preferred during ACL reconstruction surgery to reduce the PFJ contact pressure close to that of the ACL-intact condition.

The Anatomical and Biomechanical Superiority of Novel Posterior En Bloc Elevation Cervical Laminoplasty

Objectives. In this study, we performed a novel type of posterior en bloc elevation cervical laminoplasty (PEEL) to keep the integrity of the posterior structure, aiming to reduce axial symptoms complicated by a conventional cervical laminoplasty procedure. Methods. Twelve human cervical cadaveric spines (C2-T1) were sequentially tested in the following order: intact condition, open-door laminoplasty (ODL) through bilateral intermuscular approach (mini-invasive ODL), PEEL, and laminectomy (LN). After bilateral transecting at the junction of lamina and lateral mass through the tubular retraction system, the PEEL procedure symmetrically elevated all the posterior structure which was further stabilized with bone grafts and titanium plates. Computed tomography (CT) scan and biomechanical testing were performed after each condition. Results. Both mini-invasive ODL and PEEL procedures were accomplished with 2 small incisions on each side. Two types of laminoplasties could enlarge the spinal canal significantly both in cross-sectional area and anteroposterior diameter comparing with intact condition. The PEEL procedure demonstrated a significantly higher enlargement rate on a canal area and a symmetrical expansion pattern. Compared with intact condition, mini-invasive ODL performed from C3-C7 demonstrated significantly decreased motion in all testing directions except the flexion range of motion (ROM); the PEEL procedure showed mild and insignificant decrease on ROM in all directions. Laminectomy resulted in a statistically significant increase in all directions except the lateral bending ROM. Conclusions. Posterior en bloc elevation cervical laminoplasty can enlarge the canal more effectively and preserve better ROM after operation than the ODL procedure. Although technically challenging, the PEEL procedure probably would decrease the common complications associated with ODL laminoplasty.

A deep learning-based method for hull stiffened plate crack detection

Deep learning has attracted the attention of many researchers for structural health monitoring. However, it is difficult to use most of the deep learning-based techniques to detect damage throughout the life cycle of a large or inaccessible structure, especially a ship. Few studies have focused on hull stiffened plate crack damage detection. We propose such a method based on deep learning using a convolutional neural network (CNN). The model is trained on acceleration data, which are calculated by the Abaqus scripting interface. Five crack locations and four crack lengths are considered, as well as the intact condition. The effects of damping ratio, loading area, and load level on the proposed method are considered. The robustness of the proposed approach to noise and stiffener slenderness ratio are also discussed. The proposed method is compared to the multilayer perceptron method by wavelet packet transformation using the same data, so as to quantify its performance. The results show that the proposed method performs better at single- and double-crack detection, and is less sensitive to noise, damping ratio, loading area, and load level.

Tailoring selection of transforaminal interbody spacers based on biomechanical characteristics and surgical goals: evaluation of an expandable spacer

OBJECTIVETransforaminal lumbar interbody fusion (TLIF) is commonly used for lumbar fusion, such as for foraminal decompression, stabilization, and improving segmental lordosis. Although many options exist, surgical success is contingent on matching design strengths with surgical goals. The goal in the present study was to investigate the effects of an expandable interbody spacer and 2 traditional static spacer designs in terms of stability, compressive stiffness, foraminal height, and segmental lordosis.METHODSStandard nondestructive flexibility tests (7.5 N⋅m) were performed on 8 cadaveric lumbar specimens (L3–S1) to assess intervertebral stability of 3 types of TLIF spacers at L4–5 with bilateral posterior screw-rod (PSR) fixation. Stability was determined as range of motion (ROM) in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Compressive stiffness was determined with axial compressive loading (300 N). Foraminal height, disc height, and segmental lordosis were evaluated using radiographic analysis after controlled PSR compression (170 N). Four conditions were tested in random order: 1) intact, 2) expandable interbody cage with PSR fixation (EC+PSR), 3) static ovoid cage with PSR fixation (SOC+PSR), and 4) static rectangular cage with PSR fixation (SRC+PSR).RESULTSAll constructs demonstrated greater stability than the intact condition (p < 0.001). No significant differences existed among constructs in ROM (FE, AR, and LB) or compressive stiffness (p ≥ 0.66). The EC+PSR demonstrated significantly greater foraminal height at L4–5 than SRC+PSR (21.1 ± 2.6 mm vs 18.6 ± 1.7 mm, p = 0.009). EC+PSR demonstrated higher anterior disc height than SOC+PSR (14.9 ± 1.9 mm vs 13.6 ± 2.2 mm, p = 0.04) and higher posterior disc height than the intact condition (9.4 ± 1.5 mm vs 7.1 ± 1.0 mm, p = 0.002), SOC+PSR (6.5 ± 1.8 mm, p < 0.001), and SRC+PSR (7.2 ± 1.2 mm, p < 0.001). There were no significant differences in segmental lordosis among SOC+PSR (10.1° ± 2.2°), EC+PSR (8.1° ± 0.5°), and SRC+PSR (11.1° ± 3.0°) (p ≥ 0.06).CONCLUSIONSAn expandable interbody spacer provided stability, stiffness, and segmental lordosis comparable to those of traditional nonexpandable spacers of different shapes, with increased foraminal height and greater disc height. These results may help inform decisions about which interbody implants will best achieve surgical goals.