Partial Joints Research Articles

Role of unilateral partial facet joint preservation in postero-lateral approach lumbar interbody fusion for patients with degenerative lumbar spinal stenosis presenting bilateral lower limb symptoms: a retrospective study

BackgroundPosterolateral decompression and fusion with internal fixation is a commonly used surgical approach for treating degenerative lumbar spinal stenosis (DLSS). This study aims to evaluate the impact of preserving a portion of the unilateral facet joint during decompression on surgical outcomes and long-term recovery in patients.MethodsThis study analyzed 73 patients with DLSS accompanied by bilateral lower limb neurological symptoms who underwent single-level L4/5 posterolateral decompression and fusion surgery from January 2022 to March 2023. Patients were categorized into two groups based on the type of surgery received: Group A comprised 31 patients who underwent neural decompression without facet joint preservation, while Group B consisted of 42 patients who underwent neural decompression with preservation of partial facet joints on one side. Regular follow-up evaluations were conducted, including clinical and radiological assessments immediately postoperatively, and at 3 and 12 months thereafter. Key patient information was documented through retrospective chart reviews.ResultsMost patients in both groups experienced favorable surgical outcomes. However, four cases encountered complications. Notably, during follow-up, Group B demonstrated superior 1-year postoperative interbody fusion outcomes (P < 0.05), along with a trend towards less interbody cage subsidence and slower postoperative intervertebral disc height loss. Additionally, Group B showed significantly reduced postoperative hospital stay (P < 0.05).ConclusionUnder strict adherence to surgical indications, the posterior lateral lumbar fusion surgery, which preserves partial facet joint unilaterally during neural decompression, can offer greater benefits to patients.

3D pose estimation using joint-based calibration in distributed RGB-D camera system

This paper proposes a new approach that acquires camera parameters and generates an integrated 3D joint using an RGB-D camera network distributed in an arbitrary location in space. The proposed technique consists of three steps. In the first step, camera parameters are calculated using partial joints as feature points. The internal and external parameters between cameras are not calculated using a specially manufactured calibration plate. In the second step, a 3D joint set is estimated by integrating the joints obtained from each camera using the calculated camera parameters. At the same time, a 3D volumetric model in the form of a point cloud is reconstructed. The third step consists of a joint correction algorithm. The resultant 3D joint with high reliability is estimated by correcting the position of the joint using the 3D point cloud reconstructed previously. The generated 3D joint can accurately express the shape and movement of 3D human. The estimated 3D joint was compared with the joint measured using a motion capture device to evaluate its performance. The temporal standard deviation between two measurements shows very low value from 1.966 mm to 7.99 mm.

Experimental study on seismic performance of internal cruciform joints of grouting sleeve connection for modular integrated construction

Modular integrated construction (MiC) adopts room units that integrate maintenance structure, decoration and equipment pipelines in the factory-made modules, resulting in a lack of operating space for connecting modules at the construction site. In the previous research, the joints between modules are usually hinged or semi-rigid connections and partial strength joints. In this paper, a new type of joint with the grouting sleeve connection is proposed to connect modules horizontally and vertically, which is more convenient for construction and does not conflict with interior decoration. Six full-scale cruciform joints were tested to study the effect of axial compression ratio and different structural details. The test results presented the failure mode, stiffness, ductility, and energy dissipation of the specimens. The ultimate inter-story drift ratio is between 4.78 % rad and 5.96 % rad, which is larger than the requirement of 4 % rad in the special moment frame (SMF) system. The horizontal connection plate between modules can cooperate the deformation of left and right beams and columns, and significantly improve the lateral resistance of the joint. The vertical connection between modules did not slip or open and the grouting material is not broken. The inner and outer reinforced plates in the beam-to-column connection can transfer the tensile force of the beam flange well so the outer sleeve does not tear, and the wedge-shaped stiffener can inhibit the cracking of the beam-to-column connection. EC3 Part 1–8 was adopted to evaluate the stiffness characteristic of the proposed connection, indicating that the proposed joint can be classified as rigid joint for the non-sway frame. Finally, the theoretical ultimate resistance of the joint under the ideal failure mode is obtained, which is lower than the test results, indicating that the plastic development of the joint is sufficient and can be classified as full-strength joint.

Partially sleeved joints between hollow sections using self‐drilling screws.

AbstractThe present piece of research studies partial sleeve joints between similar rectangular tubes, involving bolts under shear as joining means. These are connections between two rectangular hollow sections that can be fitted one in another just by adequately cutting some faces and then bolting. For these elements, the use of self‐drilling screws is evaluated here. These connections could be removable and reusable in some cases, providing more sustainability. They also present semi‐rigid behaviour, which leads to weight saving structures and makes them ideal in many situations for structures like greenhouses or other light portal frames.The structural joints following this typology can be planned as beam‐column, ridge, or even column‐base plate joints. This paper is focused on the initial experimental results of the first two cases under bending moments, comparing them with some simplified analytical assumptions for the strength and the stiffness. These calculations are based on eccentric bolted connections with in‐plane moments but considering some particularities of these joints and joining means (self‐drilling screws).

Early Bronze Age violence in Ojo Guareña (Merindad de Sotoscueva, Burgos, Spain). Perimortem modifications in two male individuals

This paper analyses the taphonomic modifications of the human remains identified within Cueva Palomera, the main entrance to Ojo Guareña karstic system (Merindad de Sotoscueva, Burgos, Spain). The human skeletons were found deposited over the cave floor of two high, narrow and hard-to-reach sectors called Terraza del Enterramiento de la Galería Principal and Galería Sepulcral de la Sima Dolencias. Both sites represent primary depositions, in anatomical association and preserved partial joints but without grave goods. These humans are directly dated between 2000–1750 cal BC, suggesting that both events took place within a short time frame during the Early Bronze Age. The anthropological and taphonomic studies show that two adult male individuals suffered different types of lesions in their cranium, clavicle, and ribs, including traumatisms and cut marks. Taphonomic techniques have identified diagenetic and biostratinomic modifications, helping the assessment of their postmortem and perimortem interval. The morphological features of these modifications confirm that both individuals suffered lesions performed during the perimortem interval, suggesting their likely cause of death. The concentration of the injuries and the contemporaneity of both individuals are coherent with intentional anthropic action, indicating that they could result from a violent conflict.

Seismic behaviour of I-beams bolted CFST column connection using extended TSOBs

In this paper, the structural response and design method of Extended T-head Square-neck One-side Bolts (Extended TSOBs) bolted I-beams to Concrete Filled Steel Tubular (CFST) column cruciform connection were investigated under cyclic load through experimental, numerical, and theoretical approaches. The study mainly reports the effects of H-steel stiffener on seismic performance indices such as failure mode, bending bearing capacity, strength and rigidity degradations, and energy dissipation of the connection. Test results show that: (1) The H-steel stiffener can prevent Extended TSOB pull-out failure, but the relative slippage between the upper and lower columns is introduced in the strengthened connection; (2) The H-steel stiffener improves the peak bending moment, ultimate rotation, and accumulated energy dissipation of the connection by 3.3 %∼8.3 %, 33.9 %∼63.1 %, and 100.3 %, respectively; (3) The test connections can be classified as semi-rigid and partial strength joints according to Eurocode 4. The Finite Element Model (FEM) parametric analysis results show that Extended TSOB can be replaced by TSOB in the connections with H-steel stiffener and increasing the concrete grade has little effect on improving the connection bending bearing capacity. Moreover, two analysis models for calculating the bending bearing capacity of Extended TSOBs bolted I-beams to CFST column cruciform connections are proposed based on theory and tests. The accuracy and reliability of the proposed models are verified by comparing the calculated and tested bearing capacities.

Seismic performance of prefabricated joint for hollow CFDST column

While several studies have been conducted on the performance of concrete-filled double-skin steel tube (CFDST) members, only a few have evaluated the performance of prefabricated CFDST joints. In this study, we propose a prefabricated endplate bolted joint between the steel beam and CFDST column by performing a series of experiments while considering two effect parameters of the endplate type and thickness to achieve rapid construction and avoid wet work and on-site welding. Typical failure modes include plastic deformation of the endplate, local buckling of the flange end, slipping and fracture of the bolts, and fracture of the weld seam. Brittle fractures of bolts usually occur in the extended endplate joint and not in the flush endplate joint. In addition, the displacement ductility coefficients were all between 4.89 and 8.54, which indicated that the proposed joints possessed supreme ductility. Compared to the flush endplate, the extended endplate is capable of increasing the bearing capacity of the specimens by over 20%. Moreover, when the thickness of the endplate was increased to 8 mm, the maximum increment in the bearing capacity of the extended endplate joint and flush endplate joint increased by 35.91% and 30.88%, respectively. Based on the classification method in EC3, all specimens were the semi-rigid and partial strength joints. Furthermore, we propose a prediction method for the ultimate moment of the joint, which showed good agreement with the experimental results. We believe the results acquired in this study can provide a design basis for prefabricated CFDST structures.

Experimental and numerical investigation on seismic performance of extended stiffened end-plate joints with reduced beam section using high strength steel

The flexural behavior of bolted extended stiffened (ES) end-plate joints with high strength steel (HSS) is crucial in order to avoid brittle fractures in earthquakes. A total of three types of ES joints with different failure mode were carefully designed to cover commonly used types of joints, namely the full strength, equal strength, and partial strength joints. They were tested under cyclic loading to further investigate their seismic performance, and to evaluate the suitability of the design equations specified in European Code (EN 1993: 1-8 and EN 1998-1). Experimental results showed that the energy dissipation zone of the extended stiffened full (ESF) strength joints with HSS is mainly concentrated in the reduced section, while the one of the extended stiffened equal (ESE) strength joint using HSS is mainly distributed in the end-plate and the reduced section, both of them belong to ductile failure mode; the extended stiffened partial (ESP) strength joints with HSS only rely on the crack propagation and closure between the end-plate and the beam flange, and the limited plastic deformation of the end-plate to dissipate seismic energy, which presented brittle fracture; The failure mechanism and energy dissipation capacity of ES end-plate joints with HSS are closely related to the capacity design parameters αd, The capacity design calculation model of the ES joints based on the EN 1993: 1-8 code component method can accurately predict its failure mode, but the reasonable parameter αd needs to be further studied in European Code. Finite-element analysis was performed and showed good agreement with the experimental results. It was found that a higher likelihood of fracture in transition length rather than in the connection area was reconfirmed in both ESF and ESE joints, while for ESP joints, it is in the CJP weld of the beam flange end.

Seismic Behavior of Extended End-Plate Connections Subjected to Cyclic Loading on the Top-Side of the Column.

The extended end-plate connections provide excellent performance in resisting seismic loads in high-risk areas. Most scholars’ experiments and finite element studies on this type of joint are focused on the method of applying displacement loads on the beam tip, while the method of applying displacement on the column side has not been the subject of further study. However, the load transmission mechanism of this type of connection is not completely consistent in actual engineering, as the design concept of “strong column weak beam” does not apply to all joints. Therefore, in this paper, the lateral displacement of the applied column is used to simulate the seismic horizontal force to study the mechanical properties of the connection joints of the “weak column and strong beam” under the limit state of earthquake action. Based on the two internal columns (IC-EP1/2) and two edge columns (EC-EP1/2), the failure modes, strength, stiffness, moment–rotation curve, skeleton curve, ductility, and energy dissipation of this type of connection were studied. Experiment results indicated that this type of connection features semi-rigid and partial strength joints. The connection rotation angle of all specimens in the test exceeds 0.05 rad, which suggests it is an ideal seismic joints. Besides, the relationship between the thickness of the end-plate and the diameter of the bolt has a greater impact on the failure mode of the joint. The finite element (FE) analysis models were established for the above connection. The numerical model was validated against experimental results and showed acceptable consistency.

The Design of a Real-Scale Steel Moment-Resisting Frame for Pseudo-Dynamic Earthquake Testing

Background: Forthe reliable prediction of the non-linear response of structures, severe seismic events have proven to be a challenging task. Although much non-linear analysis software exists, the accuracy of the results depends on the assumptions made in the characterization of the members. Typically, the analytical models are calibrated using experimental observations. With this scope, experimental research remains the most reliable mean for the assessment of the seismic performance of structures, and it is crucial to target the development of new analytical models and design methods. Objective: Quasi-static tests can provide information on the non-linear behaviour of subassemblies, but it is often difficult to relate the imposed force or displacement histories to those that might occur during an earthquake. The pseudo-dynamic method combines an on-line computer simulation with experimental information about the tested structure, providing the application of realistic dynamic response histories. In this paper, the preliminary analysis and the design of a pseudo-dynamic testing facility for the experimental study of a real scale two storeys-two bays steel MRF, with classical and innovative joint details, are shown. Methods: Pushover and Incremental Dynamic Analyses carried out with Seismostruct software estimate the forces and displacements expected at each storey for the selected ground motions. These analyses have been performed by varying the structural detail of the beam-to-column connections. Results / Conclusion: In this paper, the analytical prediction of the performance of two bays-two storeys steel frames equipped with different solutions of beam-to-column joints is focused. Based on the performed analyses, it has been recognized that steel frames with partial strength joints can provide satisfactory performance under severe seismic actions provided that the joints are adequately designed.

Limit analysis of reinforced concrete slabs with construction joints

Reinforced concrete slabs constructed of precast elements and in situ concrete are commonly used for short-span road bridges. The construction joints between the concrete cast at different stages reduce the torsional capacity and thus the load-carrying capacity of the slab. However, the present formulations for the torsional capacity, based on limit analysis, only consider monolithically cast slabs. In this paper, the load-carrying capacity of reinforced concrete slab bridges with construction joints are investigated using limit analysis of perfect plastic materials based on the lower bound theorem. New formulations for the torsional capacity of slabs with vertical construction joints and partial construction joints are presented. The load-carrying capacity of slabs is calculated using finite element limit analysis based on the lower bound theorem. For the analysis, a complete yield criteria for the bending moments and torsional moments are setup applying a layer model. The size of the layers is calculated from the moment capacities and the derived torsional capacities. Examples of limit analysis of slabs with and without construction joints are compared, which demonstrate the reduction due to the construction joints.

Atomistic simulations of hydrogen and carbon segregation in α-iron grain boundaries

During material deformation, the coincidence site lattice (CSL) grain boundaries (GBs) are exhibiting deviations from their ideal lattice structure. Hence, this will change the atomic structural integrity by generating full and partial dislocation joints on the ideal CSL boundaries. In this analysis, the ideal Σ5 (310) GB structures and its angular deviations in α-iron within the limit of Brandon criterion, in order to conserve the dislocation core structure, will be studied in depth using molecular statics simulations. Firstly, the hydrogen and carbon atoms energetics within the GBs core structure and their free surfaces are calculated. Then Rice-Wang cohesive structure model is applied to compute the embrittlement/strengthening effect of the solute atoms on the ideal and deviated GB structures. Hydrogen showed significant embrittlement and degradation in the mechanical properties of α-iron, while carbon showed a desirable atomic strengthening effect.

Seismic evaluation and calculation models of CFDST column blind bolted to composite beam joints with partial shear interaction

With the purpose of investigating the seismic performance and failure mechanism of the concrete filled double skin steel tubular (CFDST) column blind bolted to composite beam joint with partial shear interaction, an experimental campaign was carried out to assert the effects of end plate type and column hollow ratio. Each specimen was tested subjected to cyclic lateral loads. Typical failure modes of this novel joint in conjunction with the application of partial shear interaction were examined. Based on the experimental results, the crack patterns of steel bar truss deck (SBTD) concrete slabs and hysteretic performance were also estimated. Shift of the beam neutral axis was evaluated by the analyses of the strain distributions. Furthermore, calculation models of the blind bolted composite connections to circular CFDST columns with partial shear interaction were developed based on the component method, where the sagging and hogging moments were both incorporated. For partial shear joints, the shear connector was identified as an important component to estimate its influence on the initial stiffness and moment resistance. In addition, the lower bound of the degree of shear connection was proposed to avoid the shear connector fracture under sagging moment. The predicted results from the proposed component-based models were validated by the experimental data, which demonstrated that the derived calculation models were capable of evaluating the initial stiffness and moment resistances of the CFDST column blind bolted joints to composite beams with partial shear interaction. The experimental and analytical results provide a reference for the analysis and design of blind bolted composite joint to CFDST column with partial shear interaction in engineering practice.

The structure and properties of laser seam stepper system (LSS) welded the low alloy high strength steel DOCOL 1200M with martensitic structure

This paper will present the influence of joining process parameters on the structure and properties of overlapped welded joints of 1.8 mm DOCOL 1200M steel. The obtained welded joints were subjected to micro- and macroscopic metallographic examination and hardness measurement. The visual inspections and non-destructive testing made it possible to develop the field of welding parameters to allow obtaining full penetration joints (depending on requirements) or partial penetration joints. For present welding parameters, i.e. feed rate and weld length, which are constant, the actual length of weld is determined by welding frequency. In each case, the microscopic examinations revealed martensitic structure in the weld area, and with the increase in linear welding energy the size of martensite needles became larger, especially in relation to the base material. In HAZ, the martensitic structure is tempered. It has been shown that with appropriately selected parameters the Laser SEAM Stepper method is suitable for welding the DOCOL 1200M steel. With the increase in welding power, the penetration depth increases.

APPLICATION OF PARTIAL STRENGTH CONNECTION IN THE DESIGN OF MULTI-STOREY BRACED STEEL FRAME USING TRAPEZOIDAL WEB PROFILED SECTION

Eurocode 3 offers the opportunity to design steel frames as „semi-continuous‟ by including the moment resistance of „partial strength‟ connections in plastic hinge analysis of the frame. Semi-continuous construction with partial strength connections offers many benefits for braced frames such as shallower and lighter beams, standardized connections with less complicated geometry, and more robust frames than simple construction. It is expected to give significant savings in frame weight. This paper presents findings on a series of two-bay, four-bay and six-bay braced frames of two-, four-, six- and eight-storey with span ranging from 6 m to 9 m by comparing between Hot-rolled (HR) steel beams designed using simple construction and Trapezoidal Web Profiled (TWP) steel beams designed using the semi-continuous construction method. Flush end-plate and extended end-plate connections were used as partial strength joints whereas for the simple construction, partial depth flexible end-plate connections were used as pin joints. The semi-continuous design method can reduce the frame weight between 13.4% and 20.5% compared to simple construction.

Automated Quantitative Bone Analysis in In Vivo X-ray Micro-Computed Tomography.

Measurement and analysis of bone morphometry in 3D micro-computed tomography volumes using automated image processing and analysis improve the accuracy, consistency, reproducibility, and speed of preclinical osteological research studies. Automating segmentation and separation of individual bones in 3D micro-computed tomography volumes of murine models presents significant challenges considering partial volume effects and joints with thin spacing, i.e., 50 to [Formula: see text]. In this paper, novel hybrid splitting filters are presented to overcome the challenge of automated bone separation. This is achieved by enhancing joint contrast using rotationally invariant second-derivative operators. These filters generate split components that seed marker-controlled watershed segmentation. In addition, these filters can be used to separate metaphysis and epiphysis in long bones, e.g., femur, and remove the metaphyseal growth plate from the detected bone mask in morphometric measurements. Moreover, for slice-by-slice stereological measurements of long bones, particularly curved bones, such as tibia, the accuracy of the analysis can be improved if the planar measurements are guided to follow the longitudinal direction of the bone. In this paper, an approach is presented for characterizing the bone medial axis using morphological thinning and centerline operations. Building upon the medial axis, a novel framework is presented to automatically guide stereological measurements of long bones and enhance measurement accuracy and consistency. These image processing and analysis approaches are combined in an automated streamlined software workflow and applied to a range of in vivo micro-computed tomography studies for validation.

Surgical Technique for Decompression of Severe Thoracic Myelopathy due to Tuberous Ossification of Ligamentum Flavum.

Retrospective review. To describe a safe surgical procedure, en bloc resection of the posterior wall of the thoracic canal, for the decompression of severe thoracic myelopathy caused by tuberous ossification of the ligamentum flavum (OLF). OLF has been widely recognized as a cause of thoracic myelopathy in East Asia. Surgical decompression of thoracic myelopathy caused by OLF is technically demanding. Although several surgical decompression procedures have been described, acute neurological deterioration is common. Eighteen patients with severe thoracic myelopathy caused by tuberous OLF underwent posterior decompression via segmental en bloc resection of the posterior wall of the thoracic canal. The ossified ligamentum flavum, laminae, and partial facet joints of each segment were resected en bloc. Ossified dura mater was removed if present. Posterior fixation with pedicle screws was followed by lateral bone graft fusion. The mean preoperative modified Japanese Orthopaedic Association score (total score, 11) was 4.1 (range, 2-5). Postoperatively, no neurological deterioration occurred, and all patients improved clinically. With an average follow-up of 31.2 months (range, 24-42 mo), the average modified Japanese Orthopaedic Association score was 7.8 (range, 6-10), representing a 2- to 5-point improvement. The average improvement rate was 55.2% (range, 33.3%-83.3%). Most patients were functionally independent at the last follow-up. Forty ossified segments were resected. The average time required for the resection of 1 segment was 77 minutes. Intraoperatively, dural ossification was noted in 11 patients. Complete resection was performed in all patients. Cerebrospinal fluid leakage occurred in 5 patients. Segmental en bloc resection of the posterior wall of the thoracic canal is a safe and effective alternative for OLF-related severe thoracic myelopathy.

Design and Voluntary Motion Intention Estimation of a Novel Wearable Full-Body Flexible Exoskeleton Robot

The wearable full-body exoskeleton robot developed in this study is one application of mobile cyberphysical system (CPS), which is a complex mobile system integrating mechanics, electronics, computer science, and artificial intelligence. Steel wire was used as the flexible transmission medium and a group of special wire-locking structures was designed. Additionally, we designed passive joints for partial joints of the exoskeleton. Finally, we proposed a novel gait phase recognition method for full-body exoskeletons using only joint angular sensors, plantar pressure sensors, and inclination sensors. The method consists of four procedures. Firstly, we classified the three types of main motion patterns: normal walking on the ground, stair-climbing and stair-descending, and sit-to-stand movement. Secondly, we segregated the experimental data into one gait cycle. Thirdly, we divided one gait cycle into eight gait phases. Finally, we built a gait phase recognition model based on k-Nearest Neighbor perception and trained it with the phase-labeled gait data. The experimental result shows that the model has a 98.52% average correct rate of classification of the main motion patterns on the testing set and a 95.32% average correct rate of phase recognition on the testing set. So the exoskeleton robot can achieve human motion intention in real time and coordinate its movement with the wearer.

Free from damage beam-to-column joints: Testing and design of DST connections with friction pads

Dealing with the seismic behavior of steel MRFs, in last decade, the adoption of dissipative partial-strength beam-to-column joints has started to be considered an effective alternative to the traditional design approach which, aiming to dissipate the seismic input energy at beam ends, suggests the use of full-strength joints. On the base of past experimental results, the use of dissipative Double Split Tee (DST) connections can be considered a promising solution from the technological standpoint, because they can be easily replaced after the occurrence of a seismic event. Nevertheless, their dissipation supply under cyclic loads has been demonstrated to be characterized by significant pinching and strength degradation which undermine the energy dissipation capacity. The need to overcome these drawbacks to gain competitive technological solutions has suggested an innovative approach based on the integration of beam-to-column joints by means of friction dampers located at the beam flange level. Therefore, the use of partial strength DST joints equipped with friction pads is proposed. Aiming to the assessment of the cyclic rotational response of such innovative connections, two experimental programs have been undertaken. The first one has been aimed at characterizing the dissipative performances of five frictional interfaces to be employed as dampers. The second one is aimed at the application of the same materials to DST joints specifically designed for dissipating the seismic input energy in a couple of friction dampers located at the beam flanges level. The results of the experimental analysis carried out at the Materials and Structures Laboratory of Salerno University are herein presented, showing the potential of the proposed damage-free beam-to-column joints.

Seismic Performance of a Multi-Story Composite Frame with Partial Shear Interaction and Partial Strength Joints

This study investigates the influence of partial shear interaction and partial strength beam-to-column joints on the seismic performance of a multi-story composite frame. The moment-rotation relationship of the beam-to-column joints and the force-slip curve of the beam-to-slab connections have been calibrated on the basis of available experimental tests. The results of the numerical investigations show that the energy dissipation of the composite frame increases by reducing the shear connection degree. The shear connection degree has a significant effect on the total dissipated energy in case of rigid joints, whereas in case of partial strength joints the contribution of the joints to the dissipated energy is predominant. Low shear connection degrees can provide a source of dissipated hysteretic energy, above all in case of rigid joints, and can reduce the ductility demand on other parts of a composite frame, such as partial strength beam-to-column joints. However, the shear connection degree should be high enough in order to protect shear connectors from failure.