Bone graft incorporation failure with inappropriate limb load transfer can lead to aseptic acetabular loosening of metal-on-metal prosthesis: A case report

BACKGROUND Aseptic acetabular loosening can result from various factors that can be categorized into groups:patient-related,surgeon-related and implant-related.We present a case of a 63-year-old patient who at first underwent a total hip arthro-plasty(THA)using a metal-on-metal bearing due to hip arthrosis.Follow-up visits revealed no complications after the procedure.Two years after the THA,acetabular component loosening occurred due to subsequent trauma of the opposite hip,necessitating a revision THA using a ceramic-on-ceramic bearing.CASE SUMMARY We aim to illustrate a rare case where the primary reason for undergoing THA revision was not only incomplete bone graft incorporation but also improper limb load distribution.Following the revision arthroplasty,a 9-year follow-up visit revealed improvements in all evaluation measures on questionnaire compared to the state before surgery:Harris Hip Score(before surgery:15;after surgery:95),Western Ontario and McMaster Universities Arthritis Index(before surgery:96;after surgery:0),and Visual Analogue Scale(before surgery:10;after surgery:1).CONCLUSION Opposite-hip trauma caused a weight transfer to the limb after a THA procedure.This process led to a stress shielding effect,resulting in acetabular component loosening.

Metallosis with spinal implant loosening after spinal instrumentation:A case report

BACKGROUND Spinal metallosis is a rare complication following spinal instrumentation whereby an inflammatory response to the metal implants results in the development of granulomatous tissue.CASE SUMMARY We describe the case of a 78-year-old woman who had recurrence of back pain 5 years after lumbar spine posterior decompression and instrumented fusion.Lumbar spine radiographs showed hardware loosening and magnetic resonance imaging showed adjacent segment disease.Revision surgery revealed evidence of metallosis intraoperatively.CONCLUSION Spinal metallosis can present several years after instrumentation.Radiography and computed tomography may demonstrate hardware loosening secondary to metallosis.Blood metal concentrations associated with spinal metallosis have yet to be established.Hence,metallosis is still an intraoperative and histopathological diagnosis.The presence of metallosis after spinal instrumentation likely indicates a more complex underlying problem:Pseudarthrosis,failure to address sagittal balance,infection,and cross-threading of set screws.Hence,identifying metallosis is important,but initiating treatment promptly for symptomatic implant loosening is of greater paramount.

Effect of Deep Loosening on Soil Structure and Maize Root Activity

[Objective] This study was conducted to explore the effects of deep loos- ening on soil structure and the activity of maize root system, to provide a theoreti- cal basis for the efficient and rational use of water resources. [Method] Three differ- ent loosening treatments for maize in ridges were performed in field trials as fol- lows： conventional ridge tillage, loosening the cm in spring （deep loosening in spring）, and depth of 30 cm in autumn （deep loosening in soils between rows to a depth of 30 oosening the soils between rows to a autumn）. Then the soil properties and the development of root system were measured to evaluate the effects of different loosening methods. [Result] Soil compactness was significantly reduced after deep loosening in spring, There were significant differences in soil compactness in 0-20 cm depth and soil bulk density in 0-40 cm depth between deep loosening in spring and deep loosening in autumn, deep loosening in spring and conventional ridge tillage. The soil water holding capacity was also significantly different between the two deep loosening treatments and conventional ridge tillage. Moreover, the root ac- tive absorption area of maize of deep loosening in spring was higher than that of conventionai ridge tillage. [Conclusion] Deep loosening can reduce soil compactness, bulk density, and improve soil water holding capacity, soil water content and the root activity of maize. Deep loosening in spring is better in soil improvement be- cause spring is closer to the growth period of crops than autumn. So, deep loosen- ing is conducive to the improvement of soil compactness and structure.

RANK-ligand and osteoprotegerin as biomarkers in the differentiation between periprosthetic joint infection and aseptic prosthesis loosening

AIM To assess serum levels of RANK-ligand(RANKL) and osteoprotegerin(OPG) as biomarkers for periprosthetic joint infection(PJI) and compare their accuracy with standard tests.METHODS One hundred and twenty patients presenting with a painful total knee or hip arthroplasty with indication for surgical revision were included in this prospective clinical trial. Based on standard diagnostics(joint aspirate, microbiological, and histological samples) and Musculoskeletal Infection Society consensus classification,patients were categorized into PJI, aseptic loosening,and control groups. Implant loosening was assessed radiographically and intraoperatively. Preoperative serum samples were collected and analyzed for RANKL, OPG, calcium, phosphate, alkaline phosphatase(AP), and the bone-specific subform of AP(b AP). Statistical analysis was carried out, testing for significant differences between the three groups and between stable and loose implants. RESULTS All three groups were identical in regards to age, gender, and joint distribution. No statistically significant differences in the serum concentration of RANKL(P = 0.16) and OPG(P = 0.45) were found between aseptic loosening and PJI, with a trend towards lower RANKL concentrations and higher OPG concentrations in the PJI group. The RANKL/OPG ratio was significant for the comparison between PJI and non-PJI(P = 0.005). A ratio > 60 ruled out PJI in all cases(specificity: 100%, 95%CI: 89, 11% to 100.0%) but only 30% of non-PJI patients crossed this threshold. The positive predictive value remained poor at any cut-off. In the differentiation between stable and loose implants, none of the parameters measured(calcium, phosphate, AP, and b AP) showed a significant difference, and only AP and b AP measurements showed a tendency towards higher values in the loosened group(with P = 0.09 for AP and P = 0.19 for b AP). CONCLUSION Lower RANKL and higher OPG concentrations could be detected in PJI, without statistical significance.

Competitive Failure of Bolt Loosening and Fatigue under Different Preloads

Existing research on the competitive failure relationship,failure mechanism,and influencing factors of bolt loosening and fatigue under different preloads is insufficient.This study analyzes the competitive failure relationship between bolt loosening and fatigue under composite excitation through competitive failure tests of bolt loosening and fatigue under different preloads.The results indicated that the failure mode of the bolt is only related to the load ratio(R)and is unrelated to the initial preload and excitation amplitude,which only determine the failure life of the bolt.The small axial loads of composite excitation can restrain bolt failure,and the significant degree of this restraining effect is differ-ent for different preloads.Subsequently,a fracture analysis of the bolt was performed to verify the competitive failure relationship of the bolt from a microscopic perspective,and the competitive failure mechanism of the bolt was deter-mined.Based on the findings,we propose a calculation equation for the optimal preload of 8.8 grade high-strength bolts that can serve as a reference for engineering applications.

Potential contribution of pedicle screw design to loosening rate in patients with degenerative diseases of the lumbar spine:An observational study

BACKGROUND The majority of published data report the results of biomechanical tests of various design pedicle screw performance.The clinical relevance and relative contribution of screw design to instrumentation stability have been insufficiently studied.AIM To estimate the contribution of screw design to rate of pedicle screw loosening in patients with degenerative diseases of the lumbar spine.METHODS This study is a prospective evaluation of 175 patients with degenerative diseases and instability of the lumbar spine segments.Participants underwent spinal instrumentation employing pedicle screws with posterior only or transforaminal interbody fusion.Follow-up was for 18 mo.Patients with signs of pedicle screw loosening on computed tomography were registered;logistic regression analysis was used to identify the factors that influenced the rate of loosening.RESULTS Parameters included in the analysis were screw geometry,type of thread,external and internal screw diameter and helical pitch,bone density in Hounsfield units,number of levels fused,instrumentation without anterior support,laminectomy,and unilateral and bilateral total facet joint resection.The rate of screw loosening decreased with the increment in outer diameter,decrease in core diameter and helical pitch.The rate of screw loosening correlated positively with the number of fused levels and decreasing bone density.Bilateral facet joint removal significantly favored pedicle screw loosening.The influence of other factors was insignificant.CONCLUSION Screw parameters had a significant impact on the loosening rate along with bone quality characteristics,the number of levels fused and the extensiveness of decompression.The significance of the influence of screw parameters was comparable to those of patient-and surgery-related factors.Pedicle screw loosening was influenced by helical pitch,inner and outer diameter,but screw geometry and thread type were insignificant factors.

Low-Cost Wireless Sensor Network Node Design for Multi-point Bolt Loosening Detection

Bolted connections are commonly used in aerospace structures.Once the bolts on the aircraft are damaged or loose,the consequence will be disastrous.Therefore,monitoring bolt loosening is especially required.However,periodic manual inspection costs much money and time.And it is very difficult to achieve multi-point monitoring for many bolted structures in an aircraft.Therefore,a low-cost,reliable detection method based on wireless sensor networks is presented.The reed switch is selected as a sensor for bolt loosening monitor.The chip PT2262 and PT2272are chosen as hardware codec chip for multi-point placement.A wireless transmitter and receiver circuit is designed on 315 MHz frequency.The codec chip and the wireless transmission are triggered by the reed switches.Bolt loosening is detected by the receiving terminal and indicated by light and sound alarms.The wireless transmitter and the receiver circuit are tested and the monitoring system is verified by experiments.The results show that bolt loosening can be effectively detected within 300 m.The developed sensor network is expected to solve multi-point bolt detection problems and provide a low-cost and reliable monitoring technology.

LOOSENING AND LENGTHENING OF INTESTINAL TRACT AFTER RECTAL ISOLATION IN ANUS－SAVING RESECTION FOR RECTAL CARCINOMA

In low rectal cancer surgery,the section of rectum destal to the lower tumor maigin is relaxed and lengthened after fully isolation of the organ. This would facilitate the adoption of anus saving operation.Before and after fully isolation of the rectum in low ratal cancer surgery, the distance between the lower tumor margin and the anorectal line was measured by the same rectuscope introduced through the anus.The two results were compared .The average lengthening was less than 1 cm if the lower tumor marginanorectal line distance was 5 cm.It was 1─2 cm if the lower tumor margin-anorectal distance was 6 cm.It was more than 2 cm if the distance was 7─9 cm.The loosening and lengthening of the rectal canal was related to the presence of lymphnode metastasis and the skill of the operator.The lengthening was also influenced by the body build of the patient,involvement of the rectal circumference and the Dukes stage. Modified Park's operation,trans abdominosacral resection with anastormosis of rectum,and anterior resection on transpubic approach are indicated for those in whom the lower tumor margin-anorectal line distance was 5 cm The rectectomy-anastomosis in the abdominal cavity(Dixon's operation)is indicated for those in whom the lower tumor margin-anorectal line was 6 cm.If manual anastomosis is difficult,stapling device may be used. The anus saving resection is easy if the distance was 7─9 cm.

IL-1B,IL-6 and TNF-a change of experimental knee joint degeneration model and effect of local loosening therapy

Objective To observe IL-1B,IL-6 and TNF-a level change of the joint fluid in the experimental knee joint degeneration and the effect of the local loosening therapy.Methods Thirty rabbits were divided into 3 groups at random:ten in the normal contrast group,ten in the blank model group and ten in the loosening therapy group to observe the IL-1B,IL-6 and TNF-a change of the joint fluid before and after the treatment in each group.Result IL-1B,IL-6 and TNF-a level in the blank model group was obviously higher than that in the normal group.(P<0.05).IL-1B,IL-6 and TNF-a level in the treatment group was obviously lower than that in the normal group.(P<0.05).Conclusions 1)IL-1B,IL-6 and TNF-a level of the joint fluid in the blank model group was obviously higher than that in the normal group.2)Loosening soft tissues of the knees can improve IL-1B,IL-6 and TNF-a level of the joint fluid.

Review on anti-loosening methods for threaded fasteners

Threaded fasteners naturally tend to loosen under vibration,impact,or alternating thermal load.Various anti-loosening methods or strategies are widely applied for preventing loosening,including a few anti-loosening designs and anti-loosening structures.In this review,a variety of influencing factors that improved the anti-loosening ability and helped guide the anti-loosening designs of threaded fasteners are summarized.Second,the anti-loosening structures are classified into two categories,that is,conventional and new-style anti-loosening structures.The former refers to widely used structures in engineering applications,while the latter refers to novel structures not available in the markets.The research on the evaluation and comparison of various conventional anti-loosening structures in terms of preventing loosening is summarized in detail and the newstyle anti-loosening structures from five different aspects are also surveyed based on different structural characteristics.In the future,the effects of combined factors on loosening should be considered to achieve optimal anti-loosening designs.More quantitative research on the mathematical relationship between the anti-loosening performance of conventional structures and structural parameters must be conducted.Furthermore,novel structures with excellent abilities to prevent loosening are needed,and issues of difficulties in installation and disassembly,low strength at thread,large deformation,and temperature dependence also need to be addressed.

Review of research on loosening of threaded fasteners

Loosening of threaded fasteners is a key failure mode,which is mainly caused by the slippage and friction behaviors on the thread and bearing surfaces,and will affect the integrity and reliability of products.Numerous scholars have conducted research on the loosening of threaded fasteners;however,comprehensive reviews on the loosening of threaded fasteners have been scarce.In this review article,we define loosening as a loss of preload and divide it into non-rotational and rotational loosening.The causes and mechanisms of non-rotational and rotational loosening are summarised.Some essential topics regarding loosening under transverse vibration have also attracted significant attention and have been investigated widely,including the loosening curve,critical condition of loosening,and influencing factors of loosening.The research carried out on these three topics is also summarised in this review.It is believed that our work will not only help new researchers quickly understand the state-of-the-art research on loosening,but also increase the knowledge of engineers on this critical subject.In the future,it is important to conduct more quantitative research on local slippage accumulation,and the relationship between local slippage accumulation and rotational loosening,which will have the potential to comprehensively unravel the loosening mechanism,and effectively guide the anti-loosening design of threaded fasteners.

Support design method for deep soft-rock tunnels in non-hydrostatic high in-situ stress field

Due to the long-term plate tectonic movements in southwestern China,the in-situ stress field in deep formations is complex.When passing through deep soft-rock mass under non-hydrostatic high in-situ stress field,tunnels will suffer serious asymmetric deformation.There is no available support design method for tunnels under such a situation in existing studies to clarify the support time and support stiffness.This study first analyzed the mechanical behavior of tunnels in non-hydrostatic in-situ stress field and derived the theoretical equations of the ground squeezing curve(GSC)and ground loosening curve(GLC).Then,based on the convergence confinement theory,the support design method of deep soft-rock tunnels under non-hydrostatic high in-situ stress field was established considering both squeezing and loosening pressures.In addition,this method can provide the clear support time and support stiffness of the second layer of initial support.The proposed design method was applied to the Wanhe tunnel of the China-Laos railway in China.Monitoring data indicated that the optimal support scheme had a good effect on controlling the tunnel deformation in non-hydrostatic high in-situ stress field.Field applications showed that the secondary lining could be constructed properly.

Mid-term clinical outcomes of the uncemented Robert Mathys pressfit cup

BACKGROUND The use of uncemented cups during total hip arthroplasty(THA)has gained popularity in recent years.The Robert Mathys(RM)pressfit cup,an uncemented monoblock implant is expected to preserve bone density due to its composition and external surface,while reducing backside wear with its monoblock construction.These factors should lead to a high survival rate of the implant.AIM To evaluate the mid-term survival and functional outcome of the RM Pressfit cup in a large study population.METHODS Between 2011 and 2020,we included 1324 patients receiving a primary THA using the RM pressfit cup.Final clinical follow-up was performed at 2 years postoperatively with the Dutch arthroplasty register used to assess implant status thereafter.Revision for acetabular failure and reason for revision were reported to evaluate implant survival,while the hip disability and osteoarthritis outcome score(HOOS)scores were used to assess functional outcome.RESULTS The mean age at surgery was 64.9 years.The mean follow-up was 4.6 years.Of the 1324 THAs performed,13 needed cup revisions within 5 years after index THA:5 due to aseptic loosening,6 due to infection,2 due to dislocation and 2 due to other causes.This resulted in a 5-year cup survival of 98.8%(95%CI:98.1-99.5).Nine of the cup revisions occurred within the first year after index THA.HOOS scores increased significantly in all domains during the first year and levelled out during the second year.CONCLUSION In the present study,the RM pressfit cup demonstrated excellent clinical outcomes at mid-term follow-up;however,future studies are needed to assess the long-term outcomes of this acetabular implant.

Necrolytic migratory erythema caused by pancreatic hyperglycemia with emphasis on therapeutic and prognosis:A case report

BACKGROUNDWith the incidence of pancreatic diseases increasing year by year,pancreatichyperglycemia,as one of the common complications,is gradually gaining attentionfor its impact on the skin health of patients.CASE SUMMARYThis was the case of an elderly female with clinical manifestations of necrolyticmigratory erythema,“three more and one less,”diabetes mellitus,hypertension,anemia,hypoproteinemia,and other syndromes,which had been misdiagnosedas eczema.Abdominal computed tomography showed a pancreatic caudal spaceoccupyinglesion,and the magnetic resonance scanning of the epigastric regionwith dynamic enhancement and diffusion-weighted imaging suggested a tumorof the pancreatic tail,which was considered to be a neuroendocrine tumor orcystadenoma.The patient was referred to a more equipped hospital for laparoscopicpancreatic tail resection.Post-surgery diagnosis revealed a neuroendocrinetumor in the tail of the pancreas.To date,the patient’s general condition is good,and she is still under close follow-up.CONCLUSIONNecrolytic migratory erythema can be induced by endocrine system tumors orendocrine metabolic abnormalities,with complex clinical manifestations,difficultdiagnosis,and easy misdiagnosis by dermatologists.The initial treatment principlesin dermatology include symptomatic supportive therapy and effectivedrugs to relieve skin lesions.After clarifying the etiology of glucagonoma,comprehensive treatment in collaboration with endocrinologists,generalsurgeons,and oncologists can help provide individualized treatment for patientsand improve their prognosis.

Anti-loosening performance of coatings on fasteners subjected to dynamic shear load

This paper investigates the self-loosening of threaded fasteners subjected to dynamic shear load. Three kinds of typical coatings, PTFE, MoS_2, and TiN applied to bolts and nuts, are tested in this investigation. The study experimentally examines the loosening mechanisms of fasteners and assesses the anti-loosening performance of the three tested coatings based on their tightening characteristics, loosening curves, and the damage of thread surface. Additionally, the anti-loosening performance of the three coatings is compared under different load forms. The results indicate that the PTFE and MoS_2 coatings have significant anti-loosening effect, whereas the anti-loosening performance of Ti N coating is not satisfactory. It is also found that an appropriate increase of the initial tightening torque can significantly improve the anti-loosening effect. In addition, the microscopic analyses of PTFE and MoS2 coating reveal that a reduced initial tightening torque leads to fretting wear on the thread contact surfaces of fasteners, thereby aggravating the damage.

Design and experiment of bionic stubble breaking-deep loosening combined tillage machine

Under the conditions of straw returning operation,there are three major technical bottlenecks in the Phaeozem region of northeast China,namely low stubble breaking rate,poor tillage depth consistency,and high fuel consumption.In this research,a bionic stubble-deep loosening combined tillage machine(BSD)was designed through bionic prototype analysis,coupled bionic analysis,coupled bionic design,theoretical analysis and application of intelligent control techniques.It consists of a bionic stubble breaking device and a bionic self-excited vibratory deep loosening device.Based on the unique biting pattern of locust mouthparts on maize rootstocks,the bionic stubble breaking device adopted a new multi-segment serrated bionic structure and a symmetrical rotational motion,which could significantly increase the stubble breaking rate(p<0.05)and reduce the resistance to stubble breaking operations(p<0.05).Based on the unique biology of the hare’s paws,toes and nails,the bionic self-excited vibration deep loosening device adopted a new series-parallel composite bionic elastic system and an intelligent tilling depth control system with a fuzzy algorithm,which significantly improved the tilling depth consistency(p<0.05).The operational performance of the BSD was verified at different operating speeds through comparative experiments and reveals the mechanism of its excellent performance through theoretical analysis.The final experiment results showed that,at the same operating speed,the BSD improved the stubble breaking rate by 9.62%and 10.67%,reduced the stubble breaking torque by 28 N·m and 33 N·m,reduced the tillage depth coefficient of variation by 12.73%and 13.48%,and reduced the specific fuel consumption by 36 g/km·h and 40 g/km·h compared to the two most common models.The operating performance of the three kinds of machines will decrease with the increase of operating speed,and the BSD has the least decrease.

Numerical study on transverse deformation characteristics of shield tunnel subject to local soil loosening

In this study,a refined numerical model for segmental lining of a shield tunnel,which contains detailed models of reinforcement and connecting bolts,is established using finite element software.The model is first validated by the results from a full-scale model test.Then,based on the load-structure method,this numerical model is adopted to investigate the internal force distribution and the transverse deformation characteristics of the shield tunnel when it is subject to local soil loosening.The influence of loosening position,loosening range,and loosening extent on the mechanical response is extensively studied through comprehensive numerical analyses.The results show that the main influence of local soil loosening on the ring is to disturb the force balance and change the constraint conditions,thus changing the deformation pattern and force state.After the loosening occurs,the bending moment of the ring in the loosening range increases and the axial force decreases.The vertical convergence of the ring is the largest and the equivalent stiffness of the ring is the smallest when the local soil loosened at the haunch and the loosening range a is 90°.The vertical convergence of the ring increases with increasing of the loosening extent,and the equivalent stiffness decreases linearly with increasing of the loosening extent.The results can enhance our understanding of mechanical behaviors of segmental lining associated soil loosening,and will show a possible way for detecting soil loosening based on the measured deformation and internal forces.

Therapeutic intervention for wear debris-induced aseptic implant loosening

Wear debris-induced aseptic loosening is an inflammatory bone disorder,which compromises the long-term success of total joint replacement.Despite the extensive research and great progress in treating inflammation-induced osteolysis for inflammatory arthritis,no drug has been proven for treatment/prevention of aseptic implant loosening.Also,there is very limited research on developing effective drug delivery systems for this pathological condition.In this review,we will discuss different therapeutic interventions and various delivery systems that have been developed for aseptic implant loosening.To provide the prospective for the future research in this area,the biology of wear particles-induced osteolysis,animal models developed for aseptic implant loosening and the potential challenges the field is facing are also presented in the discussion.

A Detection Method of Bolts on Axlebox Cover Based on Cascade Deep Convolutional Neural Network

This paper proposes a cascade deep convolutional neural network to address the loosening detection problem of bolts on axlebox covers.Firstly,an SSD network based on ResNet50 and CBAM module by improving bolt image features is proposed for locating bolts on axlebox covers.And then,theA2-PFN is proposed according to the slender features of the marker lines for extracting more accurate marker lines regions of the bolts.Finally,a rectangular approximationmethod is proposed to regularize themarker line regions asaway tocalculate the angle of themarker line and plot all the angle values into an angle table,according to which the criteria of the angle table can determine whether the bolt with the marker line is in danger of loosening.Meanwhile,our improved algorithm is compared with the pre-improved algorithmin the object localization stage.The results show that our proposed method has a significant improvement in both detection accuracy and detection speed,where ourmAP(IoU=0.75)reaches 0.77 and fps reaches 16.6.And in the saliency detection stage,after qualitative comparison and quantitative comparison,our method significantly outperforms other state-of-the-art methods,where our MAE reaches 0.092,F-measure reaches 0.948 and AUC reaches 0.943.Ultimately,according to the angle table,out of 676 bolt samples,a total of 60 bolts are loose,69 bolts are at risk of loosening,and 547 bolts are tightened.

Finite element analyses of Wanjiazhai water transmission tunnel excavation and service

This paper is devoted to the nonlinear stress and strain analysis oftunneling and working conditions of Wanjiazhai Division Project No.7 Tunnel in Shanxi province ofChina. The initial geological stress of loess was simulated by grading fill; the theory of unloadingproposed by Duncan and boundary stress of elasticity were used to calculate the excavation of thetunnel; Goodman joint elements were applied to simulate the joints of the liners; both loading andunloading tests have been performed to determine the parameters of Duncan-Chang's model and thecalculated results were compared; Terzaghi' s theory on loosening earth pressure was applied. Manyworking conditions were analyzed and some reasonable results were obtained. Based on the analyses,reparative measures were proposed and completed. The tunnel has functioned well since October, 2001.