Bridge Reconstruction Research Articles

Structural response reconstruction of beam-like bridge based on equivalent loads under moving forces

Response reconstruction has advantages in enriching monitoring data with high quality and it is of great importance to bridge structural health monitoring. However, there still are many current difficulties with response reconstruction due to the complex operation of bridges, e.g., hard to deal with time-varying positions of vehicles and inefficient reconstruction for cases with a long time. According to the theory of equivalent load identification, this paper proposes a model-based method for reconstructing responses induced by moving forces. The proposed method introduces moving time windows to extract the measured responses in an orderly manner and re-organizes them into a matrix form. The measured responses, expressed in matrix form, then serve as the input data to identify both equivalent loads and structural initial conditions, but not to estimate the actual moving forces. Herein, the equivalent loads represent some concentrated loads with time-invariant acting positions and are employed to approximately re-express the main information of moving forces. Matrix regularization with a sparse penalty term is used to ensure the robustness of identified results. Since the structural inputs have been estimated, the structural responses happening at the validation sensors then can be calculated as a forward problem. In this process, the role of identified structural inputs is an intermediate variable connecting the measuring sensors and the validation sensors so that, the transmissibility function (TF) discussed in the proposed method is expressed in an implicit pattern. Compared to the response reconstruction methods developed from moving force identification (MFI), an obvious characteristic is that information on the actual moving forces is no longer necessary. Therefore, it can bring convenience in practical application such as the time-varying positions of moving vehicles are not needed in advance. In addition, the application of matrix regularization has the potential for efficient computation. To verify the feasibility and effectiveness of the proposed method, both numerical simulations and experimental studies are finally carried out. The illustrated results indicate that the proposed method can accurately reconstruct the structural response. In addition, some related issues are also discussed.

Surgical Management of Massive Irreparable Cuff Tears/Management of Rotator Cuff Disease: Interpositional Graft for Irreparable Posterosuperior Rotator Cuff Tears.

Increasingly, massive irreparable rotator cuff tears present a treatment challenge due to their high re-tear rates. The reparability of such tears depends on factors like tear size, the number of involved tendons, tendon retraction extent, muscular atrophy, fatty infiltration, and the presence or absence of arthritis. There are non-surgical and several surgical treatment options described each with their specific indications, contraindications, pros, and cons. Bridging reconstruction restores the superior rotator cuff tissue and arrests humeral head superior migration. The purpose of his review is to explore the existing literature on interpositional graft mechanics, indications, surgical technique, and clinical outcomes. It aims to understand how these parameters can facilitate the incorporation of bridging reconstruction using interpositional grafts into a surgeon's practice for managing massive irreparable rotator cuff tears. Interpositional grafts for irreparable massive rotator cuff tears can either be auto-, allo-, xenografts, or synthetic material and are best suited for patients who are relatively younger, no glenohumeral arthritis, and minimal to no fatty infiltration and muscle atrophy. Short to medium term outcome studies available report good functional, clinical, and radiological improvements with bridging reconstruction utilizing acellular dermal matrix allograft. Interpositional grafts for management of irreparable posterosuperior cuff tears provides improved clinical and radiological outcomes with minimal complications and thus a viable and valuable surgical technique for a shoulder surgeon's armamentarium.

Parametric Study on The Geometric Properties of Masonry Stone Bridges with an Arch Carrier System

In this research, computational models of masonry arch bridges were constructed, taking into account distinctive features such as span dimensions, height, and arch thickness, while the arch width was maintained as a constant parameter throughout the modeling process. The finite element analysis software, ANSYS version 16, was utilized to create these computational representations. To evaluate the structural integrity and load-carrying capabilities of these bridges, loading scenarios were applied to both the center section of the bridge and a quarter of the arch span. The analytical methodology adopted for this purpose was static thrust analysis. Subsequently, the study delved into the influence of the geometrical characteristics of the arches on their load-carrying capacity. The findings of this research hold potential utility in guiding and informing the reconstruction of historic bridges that have been completely or partially demolished.

Automated Camera Pose Generation for High-Resolution 3D Reconstruction of Bridges by Unmanned Aerial Vehicles

This work explores the possibility of automating the aerial survey of bridges to generate high-resolution images necessary for digital damage inspection. High-quality unmanned aerial vehicle (UAV) based 3D reconstruction of bridges is an important step towards autonomous infrastructure inspection. However, the calculation of optimal camera poses remains challenging due to the complex structure of bridges and is therefore often conducted manually. This process is time-consuming and can lead to quality losses. Research in this field to automate this process is yet sparse and often requires high informative models of the bridge as the base for calculations, which are not given widely. Therefore, this paper proposes an automated camera pose calculation method solely based on an easily accessible polygon mesh of the bridge. For safe operation, point cloud data of the environment are used for automated ground detection and obstacle avoidance including vegetation. First, an initial set of camera poses is generated based on a voxelized mesh created in respect to the quality requirements for 3D reconstruction using defined camera specification. Thereafter, camera poses not fulfilling safety distances are removed and specific camera poses are added to increase local coverage quality. Evaluations of three bridges show that for diverse bridge types, near-complete coverage was achieved. Due to the low computational effort of the voxel approach, the runtime was kept to a minimum, even for large bridges. The subsequent algorithm is able to find alternative camera poses even in areas where the optimal pose could not be placed due to obstacles.

Vulnerability assessment and lifecycle analysis of an existing masonry arch bridge

This paper presents a comprehensive study on structural verification and proposed improvements for an ancient masonry arch bridge. The research encompasses multiple stages, starting with a detailed survey utilizing LiDAR and aerial techniques to collect precise data on the bridge’s condition. Mechanical inspections assess deterioration levels and identify critical areas requiring attention. Based on the gathered data, a structural model of the bridge is developed, considering geometric parameters and material properties. The model undergoes rigorous verification procedures to assess its seismic response and ensure compliance with safety standards. The analysis includes identifying potential collapse mechanisms, such as the formation of plastic hinges, which can lead to structural failure. The study proposes structural improvements to enhance the bridge’s performance and safety. These interventions specifically target vulnerabilities identified during the verification process. They include additional support elements, reinforcing critical areas, and utilizing advanced materials to improve tensile strength and durability. The feasibility of the proposed retrofitting solutions will be proved by performing a cost analysis, while environmental impacts are evaluated through an environmental assessment (Lifecycle Assessment — LCA) in which all the main bridge refurbishment phases have been included. Finally, some of the advantages of bridge refurbishment measures are shown by comparing the proposed intervention with a bridge reconstruction in terms of costs and environmental impacts. The outcomes of this study contribute to the existing knowledge on the rehabilitation of masonry arch bridges and serve as a valuable reference for engineers and practitioners involved in preserving architectural heritage.

Surgical management for massive rotator cuff tears: a network meta-analysis of randomized controlled trials.

Multiple surgical strategies have been developed for treating massive rotator cuff tears (mRCTs). However, there is still no consensus on the best surgical option for mRCTs. Through a network meta-analysis, we aimed to comprehensively and systematically analyse the evidence in randomized controlled trials to help clinicians make evidence-based clinical decisions for patients with mRCTs. Our study was a network meta-analysis of the surgical management of mRCTs (PROSPERO Registration ID: CRD42023397971). We searched PubMed, EMBASE, Cochrane and Web of Science for randomized controlled trials that examined the efficacy of surgical management for mRCTs up to 3 November 2022. A three-step method was employed for the study process. Study selection, data extraction and risk of bias evaluation were conducted by two independent reviewers. R software (version 4.2.1) and Stata (version 15.1) were used for the data analysis. From 10,633 publications, we included 15 randomized controlled trials (996 participants) for the quantitative analysis. In terms of both long-term and short-term surgical effects, there were no statistically significant differences among surgical interventions such as patch-augmented rotator cuff repair (RCR), RCR with platelet-rich plasma, arthroscopic decompression, bridging reconstruction, arthroscopic RCR with platelet-leukocyte membrane, open RCR, mini-open RCR, arthroscopic debridement, superior capsular reconstruction, arthroscopic suture-spanning augmented repair, subacromial balloon spacer and latissimus dorsi tendon transfer. Based on algorithms, the probability ranking suggests that patch augmentation is the most highly ranked surgical intervention for achieving better short-term surgical outcomes. Furthermore, arthroscopic-associated mini-open RCR was ranked as the highest surgical intervention for achieving better long-term surgical effects. Based on the available data from the included studies, similar surgical efficacies were observed among the reported intervention measures for mRCTs. The patch augmentation technique was found to potentially achieve better short-term surgical outcomes, which is consistent with previous reports. However, the best surgical interventions for achieving long-term surgical effects remain unknown. More high-quality research is needed to evaluate the efficacy and safety of these interventions and to guide clinical practice.

Numerical simulation analysis of construction of steel truss arch bridge with in-situ reconstruction of continuous girder bridge

In order to carry out the stability analysis of the in-situ reconstructed steel truss bridge with continuous girder bridge, this study understood the basic overview of the project and the construction scheme, which carried out the construction analysis by numerical simulation method. It is easy to find that the maximum stress of bracket is 75N/mm2 which is less than 110N/mm2.The maximum deformation is 9.2mm, and column height/500=40mm.Stability is calculated as 10.2, which is in accordance with the code. Setting the reinforcement ring at the node part, the local stress is reduced from 285 N/mm2 to 145 N/mm2, which avoids the Z-direction tearing of the steel plate. During the construction stage, the tensile stresses at the top edge of block and bottom edge were 1.4 MPa and 1.5 MPa respectively, and the normal stress meets the construction requirements. The flexural bearing capacity can be satisfied without the temperature T-degree effect in consideration. The study can provide reference for the stability analysis of related cases.s

Reconstruction of the Bridge Over the Hron River in Village Hronovce

Abstract The paper deals with the reconstruction of four-span bridge carrying the third-class road over the Hron river nearby village Hronovce. The need of immediate reconstruction of the bridge object was evocated by an accident of the middle pier. The reconstruction consisted of two phases: the sanitation of the substructure and the replacement of the original superstructure, which was in bad technical condition. This paper deals mainly with the second stage, e.g., the design of new superstructure, which was suggested as a continuous, three-span steel and concrete composite structure.

Assessment of the state of bridge crossings and geoinformation spatial analysis of regional engineering and geological conditions of their operation

The article is devoted to the assessment of engineering and geological conditions of the Ivano-Frankivsk region, as a possible factor influencing the safe operation of bridges and bridge overpasses. An analysis of the condition of the bridges was carried out according to age characteristics and the location of the structure in accordance with the engineering and geological zoning of the study area. The possible impact of landslide processes on bridges and bridge crossings was investigated using GIS methods. Reconstruction of bridges is associated with the emergency state of the bridge crossing, which arose as a result of external influences, including as a result of natural phenomena – floods, mudflows, landslides, coastal erosion, changes in the watercourses. These phenomena are especially relevant for the territory of the Carpathian region. The distribution of bridges in relation to their total number on the territory of Ivano-Frankivsk region by year is given, and the connection of their location with engineering and geological zoning is indicated. It is shown that the number of reconstructed bridges is related to the maximum total monthly precipitation. The influence of the development of dangerous exogenous geological processes on the operation of bridge crossings was assessed using the methods of geoinformation analysis. The impact of landslide processes on the state of bridges was studied. The analysis of the histograms of the distribution of the distance from the bridge to the landslide object measured by map layers in the GIS environment shows the differences in the distributions in connection with the distance to the landslides for the reconstructed bridges, which indicates the need to differentiate the assessment of damage threats. The applied statistical non-parametric Mann-Whitney U-test for the series of distances to landslides and meandering coefficients of watercourses in the area of the bridges, according to the indicator of grouping - the presence or absence of reconstructions, revealed that the samples by grouping for two types of bridges, reconstructed and not reconstructed, according parameters of distances to landslides and tortuosity coefficients, are dependent, that is, they belong to the same general population. Therefore, the distance to the landslide and the meandering coefficient of the channel are not the determining factors that affect the fact of the reconstruction of the bridge. Further analysis of the stability of bridges and bridge crossings through a detailed study of the engineering and geological conditions of the research area and the dynamics of the state of watercourses with the involvement of GIS tools should be considered logical and justified. Keywords: exogenous geological processes, landslides, engineering-geological zoning, bridge crossings, geoinformation analysis.

Transportation Resilience Modeling and Bridge Reconstruction Planning Based on Time-Evolving Travel Demand during Post-Earthquake Recovery Period

After major earthquakes, communities may experience time-evolving population in terms of size and distribution, and varying travel demands, along with the displacement and recovery of residents caused by the damage and restoration of dwelling units. Community transportation can be significantly affected if the changes in population size and distribution are considerable. As a result, the post-earthquake infrastructure reconstruction process is essentially like urban replanning to meet the realistic traffic needs of the remaining and recovering residents and further maximize the sustainability of the community. To fill the gap in existing studies that considered the travel demand as fixed during the long-term recovery stage, it is important to investigate the effects of time-evolving travel demand on transportation resilience modeling and bridge reconstruction planning during the post-earthquake recovery period. A new methodology is proposed to analyze such impact by assessing the time-dependent resilience performance of transportation networks during the post-earthquake recovery stage. Traffic efficiency and safety are the two resilience performance indicators used to evaluate the transportation network. Post-earthquake infrastructure restoration planning is conducted using a heuristic algorithm based on the time-dependent resilience performance indicator. A demonstrative case study is carried out at Shelby County, Tennessee.

Construction-Monitoring Analysis of a Symmetrical Rigid Frame Tied Steel Box Arch Bridge in Southwest China Based on Segmental Assembly Technique

Tied steel box arch bridges are increasingly being used due to their attractive appearance, high load-bearing capacity, and good stress performance. Their construction involves multiple processes and factors. Construction monitoring can ensure that such a bridge remains in its intended stress and linear states during and after construction. This helps to minimize deviations from the design state at every stage of construction. Using the segmental assembly construction technique, this study conducted construction monitoring of the alignment and force at each stage of the reconstruction of bridges using MIDAS Civil software. The construction monitoring analysis indicated that the arch rib and lattice beam were correctly placed, thereby meeting the specified requirements for arch rib closure. Displacement errors between the measured and theoretical values at each stage of construction fell within an allowable range, resulting in overall smooth bridge alignment. The measured stress in the main arch and the lattice beam generally corresponded to the theoretical stress derived from the control section stress of the entire bridge. The deviation between the cable force of the suspender and the tie rod and theoretical value fell within 10%, indicating good stress reserve. The symmetrical monitoring points in the analyzed rigid-frame tied steel box arch bridges exhibited symmetrical displacement, stress, and cable force results under various working conditions. This observation further confirms the effectiveness of construction monitoring using the segmental assembly technique.

Paper 49: Bridging Reconstruction for Large-to-Massive Rotator Cuff Tears Has a Low Rate of Cuff Arthropathy Progression at A Minimum Five-Year Follow-Up

Objectives: Rotator cuff tears cause pain, muscle weakness, and difficulty with overhead activity. While smaller tears are easier to repair, large-to-massive cuff tears (>3 cm in size) are considered irreparable. For patients with large-to-massive cuff tears, surgical options include maximal repair, superior capsular reconstruction, bridging reconstruction, tendon transfers and reverse total shoulder arthroplasty (rTSA). Bridging reconstruction was developed to improve outcomes and to avoid the morbidity associated with other technique. Bridging reconstruction, also known as graft interposition, has been shown to have superior outcomes as compared to maximal repair with better patient-reported outcomes at two-years post-operatively as recently demonstrated in a randomized controlled trial. These positive results are maintained at five years, however the midterm changes in progression of rotator cuff arthropathy and conversion to rTSA have not been assessed. The purpose is to assess the progression of rotator cuff arthropathy in bridging reconstruction patients at a five-year follow-up. Methods: Forty-four patients who underwent bridging reconstruction between 2012 and 2017 for large-to-massive rotator cuff tears were included. All patients had a minimum five-year follow-up. Data collected included demographics, pre- and post-operative Western Ontario Rotator Cuff (WORC) Index, conversion to rTSA, and X-ray readings (including acromiohumeral distance (as measured on anterior-posterior pre/post-operative radiographs) and Hamada grades for rotator cuff arthropathy). Furthermore, a sub-group analysis was performed on post-operative MRIs for graft status. Results: The mean age at surgery was 59.9± 10.8 years with a mean follow-up of 7.3±1.4 years. The population was mostly male (70.5%). Pre-operatively, seven patients had mild rotator cuff arthropathy with Hamada grade 2-3, and one patient had Hamada grade 4B. The rest of the patients had Hamada grade one preoperatively. At a minimum five-year postoperative follow-up, only one patient had a rTSA, resulting in a survivorship rate of 98%. Two patients (4.6%) had post-operative Hamada grade 4. One patient had progression of cuff arthropathy from pre-operative Hamada 3 to post-operative Hamada 4A. The other patient maintained Hamada grade 4B from pre-operative to post-operative. Patients with progression of cuff arthropathy (i.e. higher post-operative Hamada grade) appear to have a higher possibility of complete post-operative graft tears. [SS1] [JM2] There were no correlations between progression of cuff arthropathy and WORC score at five years. Conclusions: At a minimum 5-year with a mean follow-up of 7.3 years, bridging reconstruction showed 98% survivorship rate with a low rate of conversion to rTSA and a low progression of cuff arthropathy with only 4.6% of patients having advanced RCA with Hamada grade 4.

Safety and Stability Analysis of Demolition and Reconstruction of Existing Railway Bridge Piers and Caps

The process of bridge reconstruction often involves the demolition and reconstruction of bridge piers and caps, while most of the construction methods used in the previous bridge reconstruction projects changed the bridge-bearing positions. In this paper, an in situ replacement scheme of bridge piers and caps is proposed, which can maintain the existing stress state of the bridge without changing the bearing position. In order to figure out the safety and stability of the in situ replacement scheme of existing railway bridges, a steel support system model for the removal and reconstruction of the bridge piers and caps is established by ABAQUS, according to a domestic railway bridge reconstruction project, and verified by field measurement test. Based on the model, the stress and deformation of the steel support system under a trainload are analyzed, as well as those of the bearing foundation and the superstructure. The results show that the steel support system and steel pipe piles located directly below the line carrying the trainload are subjected to the greatest stress and deformation. While under various load conditions, the stress and deformation of the main components in the steel support system of the in situ replacement scheme meet the design requirements, and the structure is safe under a trainload. In addition, guided by the numerical calculation results, the implementation scheme, existing problems, and solutions of the project are introduced in detail, which can provide a reference for similar projects.

Construction of eco-crossing on traffic roads in areas of preserved nature

With the implementation of the project "Reconstruction and modernization of the main road M-18 Podgorica-Danilovgrad", which was financed by the EBRD, an upgrade and reconstruction of the 15 km long section was carried out. In this project, which included: widening of the road from 2 to 4 lanes, reconstruction of bridges, construction of new roundabouts and installation of water drainage systems, special attention was paid to environmental protection. As the section of the road is located within a key biodiversity area, during the preparation of the project numerous biodiversity studies have been carried out, all in accordance with domestic and international standards in the field of environment. During construction, numerous environmental protection measures were implemented, and one of them is the construction of an eco-crossing for animals that will enable the safe crossing of animals from one side of the road to the other. These are alternative crossings over or under major roads, in areas of preserved nature, which aim to disrupt the way of life of wild animals as little as possible and prevent their extermination, i.e., to contribute to species conservation. In addition to this, fenced openings are left on the dividing island so that the animals have enough natural light. The goal of this report is to show that, with the adaptation of the project solution, the ecological value of the project area was preserved, and that this example of adapting the road to its living space represents a successful campaign in raising environmental awareness.

Wheel-rail force identification for high-speed railway based on a modified weighted l1-norm regularization with optimal strain sensors

Wheel-rail force identification is an important inverse problem for structural health monitoring of high-speed railway train-track-bridge system. It is widely used for dynamic response reconstruction of bridges and early safety warning of dynamic reduction rate of wheel weight for the train. It can also serve as a reference for the calibration of wheel-rail force model. This paper proposes a wheel-rail force identification method for high-speed railway based on a modified weighted l1-norm regularization. Based on numerical simulations, it is found that variations of dynamic component of wheel-rail forces are very small. Therefore, the problem is transformed into the identification of three categories of static wheel weights and two categories of average dynamic components, which greatly simplifies the degree of freedom of the solution compared to traditional methods, thereby improving the solution accuracy and saving the number of sensors needed. The wheel-rail forces are decomposed into the product of a series of redundant basis functions and corresponding coefficients. The fast iterative shrinkage threshold algorithm (FISTA) and the Bayesian information criterion (BIC) are used to seek the solution of l1-norm regularization and to select the optimal regularization coefficients, respectively. Since the number of sensors and their locations have a significant impact on the accuracy of reconstructed wheel-rail forces, they are optimized using a genetic algorithm (GA), aiming to accurately reconstruct the wheel-rail forces with the minimum number of sensors at corresponding optimal positions. Numerical simulation of a 32 m box girder standard beam for high-speed railway shows that the reconstructed wheel-rail forces are in good agreement with the simulated results, which verifies the accuracy of the proposed method. In addition, the results of dynamic load test indirectly demonstrate the effectiveness of the proposed method.

The Oxymoron of the Italian Legal System: The Administrative-Law: From the Collapse of the Genoa Bridge to a Ruling of the Italian Constitutional Court

The tragic collapse of the Genoa bridge – an event that hit the world headlines few years ago, also for the huge number of casualties caused – has engendered in Italy, more recently, multifarious legal controversies. In addition to whether the Italian Government was legally entitled to terminate the long-term service concession arrangements with the private entity in charge of the maintenance of the bridge, further subtle legal issues, of a public law nature, have followed up too. As to the latter, the contribution discusses the one relating to the legal characterisation of the piece of legislation (the obscure and opaque “administrative-law”) which the Italian Government has adopted in order to rule out, apparently within any legal-contractual justification, from the public contest of the Genoa bridge re-construction, an Italian company. This entity was the one in charge of the maintenance of the Italian motorway network, including the infamous bridge. The same Italian Constitutional Law has been recently required to enter the heated debate, with an ensuing decision which, as dissected in the article, has ascertained whether the different acts of the Italian Government, promoted and implemented in the aftermath of the Genoa Bridge, were legitimate. In this very complex scenario, the contribution is also aimed, from a more theoretical perspective, at shedding a light on the myriad of laws (administrative, executive, proper laws) that in the Italian legal system have blossomed in the last decades. Genoa bridge collapse, Italian motorways and service concession arrangements, right of termination, administrative-laws, constitutional legitimacy, rule of law, due process of law, concessionaire’s rights, European Union Law, competition law

Road Temporary Collapsible Bridges

Abstract. Problem. Bridge crossings on motorways are the most vulnerable facilities. Restoration of bridges destroyed as a result of accidents, natural disasters and military operations is crucial for the functioning of Ukraine's economy and armed forces. The organisation of bridge reconstruction works on motorways remains one of the most challenging tasks. Reconstruction of bridges involves significant expenditure of effort, money and time. The main requirement is to restore destroyed bridges in a short time. The use of sets of temporary collapsible road bridges allows for the restoration of interrupted traffic across water obstacles in a short time. Goal. The goal of the research is to generalise and systematise temporary collapsible bridges of various static systems for civil and military purposes used in Ukraine and around the world. Methodology Methods of analysis and generalisation are used to systematise road temporary collapsible bridges of various static systems for civil and military purposes used in different countries. Results. The data for the use of temporary road collapsible bridges in Ukraine were obtained. The main characteristics of temporary bridges are: the size of spans, bridge length, carriageway width, load capacity, weight of bridge structures, main bridge elements, assembly time, etc. Originality. He article presents the results of generalisation and systematisation of temporary collapsible bridges of various static systems for civil and military purposes used in Ukraine and around the world. Practical value. The objective of the study was to familiarise a wide range of bridge specialists with the peculiarities of using various designs of temporary collapsible bridges and further modelling of organisational and technical solutions for their use in the context of military aggression against Ukraine.

Patient Specific Alloplastic Implant Reconstruction of Mandibular Defects-Safe Practice Recommendations and Guidelines.

Mandibular continuity defects are commonly seen after tumor resection, osteomyelitis or maxillofacial trauma. Three-dimensional reconstruction of these mandibular segmental defects is critical for proper mandibular functioning and esthetics. Various methods used to reconstruct such defects include bridging reconstruction plates, modular endoprosthesis, non-vascularized and vascularized bone grafting with stock reconstruction plate or patient specific implants (PSI) and tissue engineering bone transfer. But in the recent years, literature documents use of PSI only alloplastic reconstruction as an alternate to microvascular bone flap reconstruction. Representative cases enumerate current practice of 'patient specific implant only' mandibular reconstruction and its pitfalls. This article discusses current status of literature on PSI's, choice of indications for 'PSI only' mandibular reconstruction and also proposes guidelines for safe practice of patient specific implant reconstruction of mandible.

A Knitted PET Patch Enhances the Maturation of Regenerated Tendons in Bridging Reconstruction of Massive Rotator Cuff Tears in a Rabbit Model

Background: Although nondegradable synthetic grafts for bridging reconstruction of massive rotator cuff tears (MRCTs) have shown satisfactory clinical outcomes, their function and details on graft-tendon healing and enthesis regeneration have not been fully studied. Hypothesis: The knitted polyethylene terephthalate (PET) patch as a nondegradable synthetic graft could provide sustained mechanical support, facilitating enthesis and tendon regeneration in the treatment of MRCTs. Study Design: Controlled laboratory study. Methods: A knitted PET patch was fabricated for bridging reconstruction (PET group) in a New Zealand White rabbit model of MRCTs (negative control group), and an autologous Achilles tendon was used as a control (autograft group). The animals were sacrificed, and tissue samples were harvested for gross observation as well as histological and biomechanical analyses at 4, 8, and 12 weeks postoperatively. Results: Histological analysis showed no significant difference in the graft-bone interface score between the PET and autograft groups at 4, 8, and 12 weeks postoperatively. Interestingly, in the PET group, Sharpey-like fibers were observed at 8 weeks, while fibrocartilage formation and the ingrowth of chondrocytes were recognized at 12 weeks. Meanwhile, the tendon maturing score was significantly higher in the PET group than in the autograft group (19.7 ± 1.5 vs 15.3 ± 1.2, respectively; P = .008) at 12 weeks, with parallel-oriented collagen fibers around the knitted PET patch. Moreover, the ultimate failure load of the PET group was similar to that of a healthy rabbit tendon at 8 weeks (125.6 ± 13.6 vs 130.8 ± 28.6 N, respectively; P > .05) and no different from that of the autograft group at 4, 8, and 12 weeks. Conclusion: The knitted PET patch could not only immediately reconstruct the mechanical support for the torn tendon postoperatively in the rabbit model of MRCTs but also enhanced maturation of the regenerated tendon by fibrocartilage formation and improved the organization of collagen fibers. Herein, the knitted PET patch could be a promising candidate graft adopted in bridging reconstruction of MRCTs. Clinical Relevance: A nondegradable knitted PET patch can safely bridge MRCTs with satisfactory mechanical strength and the promotion of tissue regeneration.

Reaching into the Community to Interpret Labor History

Reaching into the Community to Interpret Labor History