Internal Tendon Research Articles

Detection of internal tendon breaks by fiber-optical measurements – influence of the re-anchoring behavior

Unannounced tendon breaks belong to the most dreaded failure mechanisms in prestressed concrete bridges. Failure of single wires or tendons does not necessarily cause concrete cracking. Hence, such damage cannot always be detected by visual inspection. In the case of tendons bonded in concrete, re-anchoring after breaking induces characteristic local strain fields: tensile strains occur between the separated extremities, while compressive strains develop around the tendons, until the initial prestressing strain is reached again. On the more distant concrete surface, these strains are rather small and depend on multiple factors, e.g., the depth of the tendon, the transfer length or the concrete stiffness.Nevertheless, such strain fields can be detected by fiber-optical sensors attached to the surface in two-dimensional grids. By evaluating the backscatter of emitted light, minimal strain changes (uncertainty: ±1 µm/m) can be recorded in quasi-continuous resolution (0.65 mm pitch). An experimental investigation of artificial tendon failure in two prestressed concrete beams is presented. The tendons were mechanically cut to simulate failure, while strains were measured on the concrete faces. The failure can be localized within a few centimeters by monitoring.The bond to the tendon mainly depends on the concrete strength. To investigate its effect on the surface strain a normal strength concrete is compared to a high-performance concrete. Better bond conditions result in lower expansion of the strain field and smaller strains in general. The results show potential to detect the position and quantity of broken tendons, solely from the strain signal on the concrete surface.

Chitin deacetylases are necessary for insect femur muscle attachment and mobility

Muscle attachment sites (MASs, apodemes) in insects and other arthropods involve specialized epithelial cells, called tendon cells or tenocytes, that adhere to apical extracellular matrices containing chitin. Here, we have uncovered a function for chitin deacetylases (CDAs) in arthropod locomotion and muscle attachment using a double-stranded RNA-mediated gene-silencing approach targeted toward specific CDA isoforms in the red flour beetle, Tribolium castaneum (Tc). Depletion of TcCDA1 or the alternatively spliced TcCDA2 isoform, TcCDA2a, resulted in internal tendon cuticle breakage at the femur-tibia joint, muscle detachment from both internal and external tendon cells, and defective locomotion. TcCDA deficiency did not affect early muscle development and myofiber growth toward the cuticular MASs but instead resulted in aborted microtubule development, loss of hemiadherens junctions, and abnormal morphology of tendon cells, all features consistent with a loss of tension within and between cells. Moreover, simultaneous depletion of TcCDA1 or TcCDA2a and the zona pellucida domain protein, TcDumpy, prevented the internal tendon cuticle break, further supporting a role for force-dependent interactions between muscle and tendon cells. We propose that in T. castaneum, the absence of N-acetylglucosamine deacetylation within chitin leads to a loss of microtubule organization and reduced membrane contacts at MASs in the femur, which adversely affect musculoskeletal connectivity, force transmission, and physical mobility.

Experimental modal analysis of a rotating tendon-loaded helicopter blade demonstrator

A novel concept which uses an internal tendon to apply a compressive force on the blades for resonance avoidance of rotorcraft, so-called ‘active tendon concept’, was put forward recently. This research enhances the active tendon concept further toward its basic experimental validation in the rotating operational conditions. To progress in this direction, a new fully dynamically instrumented demonstrator combined with the displacement-based axial load application system is developed and assessed experimentally in non-rotating and rotating conditions for the rotor speeds ranging from 0 rpm to 500 rpm and axial compressive loads ranging from 0 N to 500 N. The identified modal dynamics is used to validate the comprehensive reduced-order model which is subsequently used to support the interpretation of the rotating results where the applied experimental methods lacked in resolution of range.It is observed that the rotating system features anticipated modal dynamics in the form of centrifugal stiffening and compressive softening of the beam-dominated modes, whilst the tendon-dominated modes display rapid stiffening effects with the applied axial loads. As a result of these opposing trends, further interactional phenomena such as modal veering are observed experimentally and in model-predicted results. One consistently observed beam-dominated mode is used to extend the range of the experimental observations beyond those supported by the models toward the damping characterisation throughout the veering interactions and complex strain mode analysis.The results presented in this work confirm the anticipated modal behaviour and suggest that the rotating systems can be influenced through controllable preloads whilst in the state of rotation. Additional vibration and load control opportunities arise from the emergent and tunable interactional dynamics between the primary beam or blade system and the secondary augmented tendon preload application system.

Non-uniform displacement within ruptured Achilles tendon during isometric contraction.

The purpose of this study was investigate tendon displacement patterns in non-surgically treated patients 14months after acute Achilles tendon rupture (ATR) and to classify patients into groups based on their Achilles tendon (AT) displacement patterns. Twenty patients were tested. Sagittal images of AT were acquired using B-mode ultrasonography during ramp contractions at a torque level corresponding to 30% of the maximal isometric plantarflexion torque of the uninjured limb. A speckle tracking algorithm was used to track proximal-distal movement of the tendon tissue at 6 antero-posterior locations. Two-way repeated measures ANOVA for peak tendon displacement was performed. K-means clustering was used to classify patients according to AT displacement patterns. The difference in peak relative displacement across locations was larger in the uninjured (1.29±0.87mm) than the injured limb (0.69±0.68mm), with a mean difference (95% CI) of 0.60mm (0.14-1.05mm, P<.001) between limbs. For the uninjured limb, cluster analysis formed 3 groups, while 2 groups were formed for the injured limb. The three distinct patterns of AT displacement during isometric plantarflexion in the uninjured limb may arise from subject-specific anatomical variations of AT sub-tendons, while the two patterns in the injured limb may reflect differential recovery after ATR with non-surgical treatment. Subject-specific tendon characteristics are a vital determinant of stress distribution across the tendon. Changes in stress distribution may lead to variation in the location and magnitude of peak displacement within the free AT. Quantifying internal tendon displacement patterns after ATR provides new insights into AT recovery.

시체 손 실험연구를 이용한 손 내부 건의 힘과 외부 악력과의 관련성 연구

시체 손 실험연구를 이용한 손 내부 건의 힘과 외부 악력과의 관련성 연구

Tensile load on the flexor digitorum profundus tendon during palmar and lateral blocking exercises: Influence on blocking force and distal interphalangeal joint flexion angle

Study DesignThis is a basic science research. IntroductionIsolating excursion of the flexor digitorum profundus (FDP) in zones I and II is common practice in the current management after flexor tendon repair. During this procedure, the proximal interphalangeal joint is sometimes fully extended with unmeasured external forces at the middle phalanx when the distal interphalangeal joint is actively flexed. Purpose of the StudyThe purpose of the study was to investigate the incremental effect of external force with palmar blocking versus lateral blocking and increased angles of flexion on internal tendon forces at the repair site for a safer application of force by the treating therapist. MethodsEight human cadaveric fingers were studied. To simulate palmar or lateral finger blocking, a compression force of blocking was applied from 5N (510 grams) to 25N (2,550 grams) on the skin surface of the palmar or the lateral aspect of each of these middle phalanges in 5N increments. The tensile load on the FDP tendon during distal interphalangeal joint flexion from 0° to 60° was measured in 10° increments. ResultsDuring palmar blocking, the tensile load was significantly increased with increases in palmar blocking force. However, no significant increase in the tensile load on the FDP tendon was observed at any lateral blocking. DiscussionLateral blocking exercise can be performed with less tensile force on the FDP tendon when performing blocking exercise after flexor tendon injury repair. ConclusionsThis study supports the concept that lateral blocking with incremental joint angles allows a safer application of force for the healing tendon.

Short-term effect of double bundle reconstruction of posterior cruciate ligament with total internal short tendon technique

To explore the method and curative effect of double bundle reconstruction of posterior cruciate ligament with total internal short tendon technique. From October 2010 to June 2018, 50 patients with simple posterior cruciate ligament rupture were admitted, including 35 males and 15 females, ranging in age from 20 to 45 years old, 16 with acute injury and 34 with old injury. The posterior cruciate ligament (PCL) was reconstructed by double bundle technique with the whole internal short tendon. The two ends of the transplanted ligament were fixed by titanium plate suspended with adjustable loop. The Lysholm knee score and IKDC score were used to evaluate the clinical effects. All the 50 patients were followed up, and the duration ranged from 6 to 60 months, with a mean of (28.84±9.52) months. At the latest follow up, the knee joint activity returned to normal range. The median value of Lysholm knee score was 54 before operation and 100 after operation. According to the IKDC score, there were 0 case of grade A, 0 case of grade B, 20 cases of grade C and 30 cases of grade D before operation;29 cases of grade A, 19 cases of grade B, 1 case of grade C and 1 case of grade D after operation;the difference was statistically significant (P<0.01). Arthroscopic double bundle reconstruction of posterior cruciate ligament with short internal tendon is safe and reliable, with less tendon transplantation, more stable fixation, and more bone reserve, which is beneficial for healing and renovation. The short term effect is positive.

음향방출 기술을 이용한 PSC 구조물 내부 텐던의 파괴거동 연구

프리스트레스트 콘크리트 (Pre-Stressed Concrete; PSC) 공법은 긴장재를 콘크리트 외부 또는 내부에 위치하여 적용하며 고가도로 등 교량 건설에 많이 적용되었다. 외부 텐던은 점검자가 접근이 가능하여 파단이 발생한 경우 여러 가지 점검 방법을 통하여 상태 평가가 가능하나, 내부 텐던의 경우 콘크리트 내부에 위치하여 결함이 발생할 경우 현존하는 비파괴 검사 기술로 탐지 하는데 한계가 있다. 본 연구에서는 음향방출 기술을 이용하여 PSC 교량의 내부 긴장재 파괴 거동에 대한 감시를 수행하고, 내부 텐던파괴 시에 발생하는 특정 데이터를 분석하여 텐던의 이상감지를 수행하였다. 인위적으로 손상된 내부 텐던이 그라우트 처리된 PSC 실험체에 반복하중과 인장 파괴실험을 적용하여 PSC 구조물의 물리적 거동을 관측하였다. 반복 하중 시험 중 최대 하중(6.5 ton) 도달 시점 2차례에 걸쳐 콘크리트 표면 균열이 확인과 기준 신호 레벨 대비 1,000 aJ 이상 큰 AE Energy가 계측되었고, 인장 파괴 시험 시 약 8 ton 하중에서부터 콘크리트 균열의 급격한 성장과 이때 AE Energy는 10,000 aJ 이상의 값이 계측되었으며, 하중이 13 ton에 도달했을 때, 긴장재가 파단되면서 약 50,000 aJ의 AE Energy가 돌발적으로 계측되었다. 반복실험 및 인장 파괴실험에서는 AE energy, Ib value, frequency features로 콘크리트 파괴거동에 대한 구분을 수행하였다. 특히 Initiation Frequency, Reverberation Frequency 로서 텐던의 파괴거동에 대한 분석이 가능함을 확인하였다.

Morpho-textural changes of the patellar tendon in professional volleyball players: a six month longitudinal study

Abstract Introduction Tendinopathy is a term used to describe a clinical presentation of pain and dysfunction, which, at times, is accompanied by pathologic structural changes in the tendon matrix. Jumper's knee has been studied for some time, however the etiology is still unknown. The deep fibers of the proximal region are the most affected area in tendinopathies affecting the patellar tendon. Ultrasound (US) scanning may have the greatest sensitivity for confirming clinically diagnosed patellar tendinopathy compared with other imaging techniques such as magnetic resonance. Some studies have found that a minimum of six months is required to observe significant structural changes, although other studies reveal that structural changes can be visible in a shorter period of time. Thus, sonography has been used to evaluate quantitative variables such as thickness, echogenicity, texture measures and the internal tendon matrix. Objective The purpose of this study was to evaluate the sonographic behavior of morpho-textural changes of the patellar tendon in professional male volleyball players over a one year season. Material and Methods This is an observational, longitudinal and analytical study. A sample of 66 patellar tendons from 33 volleyball players of the Spanish super league was recruited, with an average of: 28 years, 86kg and 192cm. An ultrasound scan was performed using the Sonosite Titan ultrasound system, L38, 5–10 MHz, with a cross section of 5mm from the lower pole of the patella. Two depths were analyzed: a.39mm: echogenicity, echogenicity variation, circularity, width and thickness. b.24mm: entropy and contrast. Statistical analysis and analysis of variance (ANOVA) was performed for repeated measures and, in addition, the effect size was calculated with Cohen's d. The confidence interval was 95%. SPSS Statistics software was used. Results For textural variables: contrast increased significantly with an average effect size, and entropy showed no significant difference. Circularity was significantly lower. Width was shown to be significantly greater, with an average effect size, while thickness was reduced significantly. Regarding echogenicity, no significant changes were detected and variation in echogenicity did not show significant changes. Conclusions Imaging analysis could be a potential tool to detect changes in the pattern of patellar tendons. Some morpho-textural changes were found in male volleyball players: the textural contrast variable increases significantly throughout the annual season, meaning that the tendon becomes slightly flatter and loses circularity in its transverse section. The entropy and echogenic parameters obtained from the gray-scale histogram did not reveal any significant changes.

Shear Behavior of Epoxy Resin Joints in Precast Concrete Segmental Bridges

Epoxy resin joints for precast concrete segmental bridges protect internal posttensioned tendons from corrosion, compensate for irregularities between joint interfaces, and act as a joint lubricant. The shear strength, shear behavior, and crack pattern of the epoxy resin joints with castellated keys were investigated for 25 full-depth male–female shear key specimens match cast with a variety of key geometries, distances, numbers, and angles, internal tendon layouts and reinforcing bars. It was found that these design parameters not only effected joint shear strength but also changed epoxy resin joint failure modes and ductility. Several previous datasets were collected to evaluate six analytical expressions for epoxy resin joint shear strength, and recommendations for their use are presented. An improved analytical expression is proposed to predict the shear strength of epoxy resin joints with reinforced keys.

Two-dimensional biomechanical thumb model for pipetting

Manual pipetting imposes repetitive movements, high force, and awkward postures on the thumb, fingers, and wrist, increasing the risk of musculoskeletal injuries. The purpose of this study is to provide a linear regression model to estimate the optimal pipetting grip height based on the two-dimensional biomechanical static thumb model developed in this study. This biomechanical static thumb model uses hand anatomy and static equilibrium conditions to estimate internal tendon forces against a given external force. Based on the model, we conclude that the optimal grip height is 3 cm in males and 2 cm in females in terms of grip strength and force efficiency. In addition, the model is validated by RMS EMG data from correlation analysis between the predicted internal tendon forces, with RMS EMG values of 0.65 for Flexor Pollicis Longus, 0.57 for Flexor Pollicis Brevis, and 0.61 for Adductor Pollicis.

The pyramidalis\u2013anterior pubic ligament\u2013adductor longus complex (PLAC) and its role with adductor injuries: a new anatomical concept

PurposeAdductor longus injuries are complex. The conflict between views in the recent literature and various nineteenth-century anatomy books regarding symphyseal and perisymphyseal anatomy can lead to difficulties in MRI interpretation and treatment decisions. The aim of the study is to systematically investigate the pyramidalis muscle and its anatomical connections with adductor longus and rectus abdominis, to elucidate injury patterns occurring with adductor avulsions.MethodsA layered dissection of the soft tissues of the anterior symphyseal area was performed on seven fresh-frozen male cadavers. The dimensions of the pyramidalis muscle were measured and anatomical connections with adductor longus, rectus abdominis and aponeuroses examined.ResultsThe pyramidalis is the only abdominal muscle anterior to the pubic bone and was found bilaterally in all specimens. It arises from the pubic crest and anterior pubic ligament and attaches to the linea alba on the medial border. The proximal adductor longus attaches to the pubic crest and anterior pubic ligament. The anterior pubic ligament is also a fascial anchor point connecting the lower anterior abdominal aponeurosis and fascia lata. The rectus abdominis, however, is not attached to the adductor longus; its lateral tendon attaches to the cranial border of the pubis; and its slender internal tendon attaches inferiorly to the symphysis with fascia lata and gracilis.ConclusionThe study demonstrates a strong direct connection between the pyramidalis muscle and adductor longus tendon via the anterior pubic ligament, and it introduces the new anatomical concept of the pyramidalis–anterior pubic ligament–adductor longus complex (PLAC). Knowledge of these anatomical relationships should be employed to aid in image interpretation and treatment planning with proximal adductor avulsions. In particular, MRI imaging should be employed for all proximal adductor longus avulsions to assess the integrity of the PLAC.

Investigation of index finger triggering force using a cadaver experiment: Effects of trigger grip span, contact location, and internal tendon force

A cadaver study was conducted to investigate the effects of triggering conditions (trigger grip span, contact location, and internal tendon force) on index finger triggering force and the force efficiency of involved tendons. Eight right human cadaveric hands were employed, and a motion simulator was built to secure and control the specimens. Index finger triggering forces were investigated as a function of different internal tendon forces (flexor digitorum profundus + flexor digitorum superficialis = 40, 70, and 100 N), trigger grip spans (40, 50, and 60 mm), and contact locations between the index finger and a trigger. Triggering forces significantly increased when internal tendon forces increased from 40 to 100 N. Also, trigger grip spans and contact locations had significant effects on triggering forces; maximum triggering forces were found at a 50 mm span and the most proximal contact location. The results revealed that only 10–30% of internal tendon forces were converted to their external triggering forces.

Nonlinear analysis of containment structure based on modified tendon model

This paper proposes a modified stress–strain relation for bonded internal tendon in containment structures on the basis of the tension stiffening effect and the bond characteristics between a tendon and its surrounding concrete. Differently from general approaches for the consideration of bond-slip, which take the double nodes in defining the displacement field, the proposed model indirectly considers the bond-slip effect through the modification for the stress–strain relation of tendon. Since the proposed tendon model takes into account the bond-slip effect without taking double nodes in the numerical modeling of containment structures, it can effectively be implemented into commercialized programs which have a lot of limitation in considering the bond-slip effect at large complex containment structures. The solution algorithm for an un-bonded internal tendon whose structural response is not section-dependent but member-dependent is also introduced. The different structural responses from those in bonded tendon are evaluated by successive iterations and finally considered by the additional modification for the stress–strain relation of tendon. The validity of the proposed tendon model is verified through correlation studies between analytical and experimental results for PSC beams and 1/4 PCCV containment structures.

Development of Two-Dimensional Biomechanical Modeling of the Thumb for Pipetting

The aim of this study is to develop a two-dimensional biomechanical static thumb model based on the posture of the hand using pipette. This model used hand anatomy and static equilibrium conditions to estimate internal tendon forces against a given external force. The input variables can be divided into two groups: 1) joint angle, external load and bone length, which are directly measured from the test; and 2) tendon force ratio and moment arm, which are adopted from previous studies. The thumb model was simulated using an FSR (forcesensing resistor) and validated using an Electromyography (EMG) system with four grip heights from 1 to 4 cm and with two tasks: Aspirating and Dispensing. A similar trend was observed between the simulation and EMG results. The average thumb pressure for Dispensing tasks is about 3.1 times greater than that for Aspirating, and the overall force efficiency ratio for both tasks is around 8 times the external load. The optimal grip height is 3 cm in terms of grip strength, 1 or 3 cm in terms of minimum internal force and 1 cm in terms of force efficiency. Overall, the optimal grip height is 1 or 3 cm.

Investigation of Triggering Force by the Index Finger for Optimal Trigger Design Using a Cadaver Experiment

This study determined the optimal trigger grip span for the index finger and contact location between the index finger and trigger, using a cadaver experiment. Three fresh-frozen right male cadaveric hand specimens without any medical problem were employed, and the index finger motion simulator (IFMS), consisting of 1) support frame, 2) force measurement system, 3) motion delivery unit, and 4) operation system, was developed to support and control the specimens. The experiment consisted of two phases: triggering force was observed as a function of 1) grip spans (40, 50, 60 mm) and 2) three contact locations on the middle of the distal to the middle of the medial phalange. Also, three levels of total tendon forces (FDP + FDS: 40, 70, and 100 N) were applied to both phases. As a result, at Phase I, the maximum triggering forces, 8.9, 15.0, and 20.0 N, were obtained at 50 mm grip span for total tendon forces respectively. At Phase II, The contact location on the middle of the medial phalange showed the maximum triggering forces, 10.1, 18.2, and 28.2 N, for the total tendon forces respectively. Force efficiency, triggering force to tendon force ratio, showed approximately 10 to 30% of internal tendon force was converted into external trigger force. On the basis of the results of this study, 50 mm grip span and the contact location on the middle of the medial phalange were recommended for optimal trigger design.

Flexural Capacity of Fiber-Reinforced Polymer Strengthened Unbonded Post-Tensioned Members

Experimental and analytical investigations were carried out for evaluating the nominal moment capacity of unbonded posttensioned members when strengthened using external fiber reinforced polymer (FRP) composites. In the experimental part of the study, 36 simply supported specimens were tested to failure. The main test parameters included area of internal tension reinforcement, area of external FRP reinforcement, span-depth ratio of the member, profile of the prestressing tendons, and type of concrete structural system. In the analytical part of the study, a design-oriented procedure for evaluating the nominal moment capacity of FRP-strengthened post-tensioned members with internal or external unbonded tendon systems is developed. The procedure is consistent with the approach proposed in ACI Committee 440 report for reinforced concrete or bonded prestressed concrete members, and is applicable for both simply supported and continuous members. The accuracy of the design approach was verified by comparing it with the test results of the experimental part of this investigation.

Calculation of Crack Width of Steel-Concrete Composite Beams Prestressed with Internal Tendon

Steelconcrete composite beam prestressed with internal tendon (SCCPIT) is composed of prestressed concrete slab, steel beam and shear connectors, etc. At present, there is no calculation formula for crack width of SCCPIT in current design codes Eurocode 4, ASSHTO or Chinese Code for Design of Steel Structures (GB 500172003). In this paper, the calculating formulas for crack width provided in Code for Design of SteelConcrete Composite Structure (DL/T 50851999) were adopted as a basis for modification. On the basis of available test results, the calculation formulas for uneven coefficient of reinforcement strain and average crack space were modified by consideration of concrete slab width and combined force ratio. Hence, empirical calculating formulas of crack width of SCCPIT under negative moment were proposed. In order to verify the accuracy of the proposed formulas, five simply supported SCCPITs previously conducted by research group were analyzed, and comparisons indicated that the calculated values are in good agreement with the test results.

Development of the Two-Dimensional Biomechanical Hand Model for a Guitar Player

In this study, a two-dimensional biomechanical hand model predicting tendon loads in the fingers during guitar playing was developed. To estimate tendon forces, joint reaction forces, and force reactions against a given fingertip pressure (external force), a static hand model was developed based on the hand anatomy and static equilibrium conditions. Model inputs included 1) adopted existing anthropometry data, 2) fingertip pressures measured while playing the guitar, and 3) measured joint angles on the fingers. The hand model evaluated four chords: C, E, G7, and Am. G7 required the highest internal tendon force (41.0N), and Am (32.8N), E (30.3N), and C (26.6N) followed it. The index finger was mainly recruited for all four chords while the ring finger showed the worst efficiency, using the external force to internal tendon force ratio. Finally, the quick-and-dirty test showed the simulation result had strong correlation ( R2= 65.1 %) with EMG result (C: 22.9%MVC, E: 22.1%, G7: 34.8%, and Am: 34.3%) on the FDP muscle, a main flexor of the finger.

Weak link of tendon–bone healing and a control experiment to promote healing

This study aims to observe the mechanical weak point and histological features of tendon-bone interface after anterior cruciate ligament reconstructive surgery and to explore the tendon-bone healing effects of the platelet-rich gel (PRG) + deproteinized bone (DPB) compound. A total of 48 New Zealand white rabbits were randomly divided into normal group, model (without embedding), experimental (embedded with the PRG + DPB compound), and control (embedded with DPB) groups. The rabbits were executed at 2, 4, 8, and 12 weeks after the operation. Then, micro-computed tomography scan and uniaxial tensile test were conducted. The fractured specimens were subjected to histological observation. At 4, 8, and 12 weeks after the operation, the bone density of the tendon-bone bound section of the experimental group was higher than that of the other groups (P < 0.05). At 4 and 8 weeks, the maximum tensile load of the experimental group was obviously higher than that of the control and model groups (P < 0.05). Histological observation indicated that the tendon-bone interface in the experimental group had more cartilage and bone tissue growing toward the internal tendon, but the fracture layer mainly occurred in the non-ankylosed part. The mechanical weak point of the early tendon-bone interface was in the immature fibrous tissue. The PRG + DPB compound can effectively trigger tendon-bone healing by promoting the maturation and ossification of the tendon-bone tissue. This compound improved the tensile strength of the healing interface and reduced bone tunnel enlargement.