Soft Failure Research Articles

Implementing Self-Healing N-Policy Queueing Models and their Impact on IoT Design Applications

We embarked on a comprehensive exploration of a single server queueing design, with a specific focus on handling soft failures. Soft failures refer to instances where customers do not need to be removed but rather need to wait for the server to be reactivated. These occurrences can happen at any time during the server's operation. When a soft failure occurs, the process automatically initiates a repair action, which we will refer to as the self-healing time. This self-healing time is relatively short, as the server possesses a remarkable restoration capability. Once the repair is complete, the server resumes its service provision and resumes normal operations. Moreover, during periods of prolonged idleness, the server can enter a dormant state, akin to a vacation mode. This dormant state is triggered when the server awaits the accumulation of N or more users. Once the threshold is reached, the server transitions into a busy state and resumes its normal operations This study represents the pioneering integration of soft failures with the N policy, marking the first of its kind in this field. Additionally, we provide explicit expressions for the transient probabilities of the model, employing generating function methodology and Laplace transform techniques. Furthermore, we include performance measures and a numerical component to underscore the significance of the model's parameters.

Analysis of Single Server Markovian Queueing Model with Differentiated Working Vacation, Vacation Interruption, Soft Failure, Reneging of Customers

This article investigates the reneging of customers in M/M/1 model with differentiated working vacation, vacation interruption and soft failure. The customers come with rate λ and receives service during busy period with rate μ, where λ and μ obeys markovian distribution. In this model two distinct vacations are considered: one has been taken just after serving all customers in busy period with slow service rate θ as some soft failure occurs during working vacation (Vacation I). At an epoch of completion of working vacation, if any customers are present in the system, then the server moves to busy period for serving customers otherwise move to vacation II. During vacation II if customer comes then interruption is assumed to occur in the vacation and server returns to busy period otherwise remain in vacation .When an arriving customer finds server is on working vacation, it makes customer impatient and it start up an impatient timer T0 with an exponentially distributed rate α0 If service does not begin before T0 expires, the customer might renege with probability p without getting served or wait for their turn with probability 1-p=q. By using PGF technique we have derived different steady state probabilities and various system performances analytically. Effect of few parameters on different system performances have been shown numerically and illustrated graphically.

Failure Modes in Orthopedic Oncologic Reconstructive Surgery: A Review of Imaging Findings and Failure Rates.

Limb salvage surgeries utilizing endoprostheses and allografts are performed for a variety of oncologic conditions. These reconstructions can fail and require revision for many reasons, which are outlined and classified into mechanical failures (soft tissue failures, aseptic loosening, structural failure), non-mechanical failures (infection, tumor progression), and pediatric failures (physeal arrest, growth dysplasia). Distinct radiologic and clinical findings define specific failure subtypes but are sparsely illustrated in the radiology literature. Specifically, an understanding of the organizational structure of the failure modes can direct radiologists' search for post-reconstruction complications, enhance an appreciation of their prognostic significance, and facilitate research by standardizing the language and conceptual framework around outcomes. The purpose of this review is to highlight the key radiologic findings and imaging studies of each failure mode in orthopedic oncologic reconstructive surgery in the context of risk factors, failure rates, prognosis and survival statistics, and clinical decision-making regarding chemotherapy, radiation, and revision surgery.

Reliability Analysis for Degradation-Shock Processes with State-Varying Degradation Patterns Using Approximate Bayesian Computation (ABC) for Parameter Estimation

The degradation of products is an integral part of their life-cycle, often following predictable trajectories. However, sudden, unexpected events, termed ’shocks’, can substantially alter these degradation paths. Shocks can significantly influence the pace of degradation, leading to accelerated system failure. Moreover, they may initiate changes in degradation patterns, transitioning from linear to non-linear or random trajectories. To address this challenge, we present a novel multi-state reliability model for competing failure processes that account for degradation-shock dependencies by considering the state-varying degradation pattern. The degradation process is divided into s-states, with each state treated according to its pattern based on the time-transform Wiener process. The reliability function is derived based on soft failure caused by continuous degradation involving the s-states, the sudden increase in degradation caused by random shocks, and hard failure due to some shock processes. Additionally, we performed a sensitivity analysis to determine which parameters have the most significant impact on product reliability. Due to the complexity of the likelihood function, we adopted the ABC method to estimate the model parameters. A simulation study and a practical application with micro-electro-mechanical systems (MEMS) degradation results are used to demonstrate the efficiency and effectiveness of the proposed approach.

Prosthesis applications and challenges in children with earthquake-related amputations

BackgroundAmputations are among the most important traumatic injuries caused by earthquakes. However, data on amputee children and prosthesis application is quite limited in the literature. The aim of the study is to evaluate the injury-related data, stump problems, prosthesis application, difficulties and complications experienced with prosthesis during follow-up of children with 2023 Kahramanmaraş earthquake-related limb loss. Patients and methodsSociodemographic and injury-related data, pre-amputation and post-amputation interventions, prosthesis application, current prosthetic problems, and revision surgeries of the amputee children were recorded. ResultsMedian age of patients (n = 102) admitted to our center was 13.0 years. 67.6 % of patients had one or more concomitant injuries. Median time and number of amputations were 4 (0–57) days and 1 (1–4), respectively. Of the total 120 amputations, 67.5 % (n = 81) were lower extremity amputations. Most common amputation levels were transtibial (29.1 %, n = 35), transfemoral (22.5 %, n = 27), and transhumeral (15.8 %, n = 19). Most amputees (56.8 %) underwent revision surgery after initial amputation. Median duration of time from amputation to prosthesis application was 184 (28–314) days. For 25 prostheses, a socket revision was required. Six patients had surgical revision of the stumps to allow prosthetic fit and mobility (due to bone overgrowth, soft tissue failure, heterotopic ossification). ConclusionLimited healthcare facilities, surgeries performed under emergency conditions, accompanying multiple traumas, inadequate follow-up conditions, and additional difficulties arising from the pediatric patient group lead to difficulties in the care of pediatric amputee patients. Our results will guide the care of this vulnerable patient population in the event of a similar unfortunate disaster.

Non-coaxial plasticity of similar weakly cemented soft rock under directional shear stress path

The plastic flow behavior of soft rock exhibits non-coaxial features under complex stress paths, while traditional plasticity theories are ill-equipped to adequately represent this, which leads to the mechanism of soft rock failure still unclear. To investigate the evolution law of strain increments and non-coaxial characteristics of weakly cemented soft rock, the directional shear tests are conducted using the hollow cylinder apparatus (HCA). The results show that non-coaxiality does not occur when α is distinct from 0° or 90°. The oscillation of the non-coaxial angle is significantly more variable in soft rock experiencing combined tension–torsion (45° < α < 90°), as opposed to those under the influence of combined compression-torsion (0° < α < 45°). The non-coaxiality swiftly dissipates when the sample is approaching the failure state. The stress rate is decomposed into stress magnitude and direction to describe non-coaxial features of plastic strain. And a new method for non-coaxial stress rate is proposed which can express the plastic strain increment directions. The spherical interpolation coefficient method is utilized to describe the continuous change in non-coaxial plastic flow direction between tangential and normal directions of the yield surface. The non-coaxial parameter (Δ) is introduced to quantify the non-coaxial characteristics of soft rock and its validity is confirmed through test results. This method effectively captures the principal stress direction influence on non-coaxial behavior of soft rock and have significance for rock mechanics.

Integrating parametric HFGMC and isogeometric RZT[formula omitted] for multiscale damage modeling of composite structures: A numerical and experimental study

In this research effort, a novel multiscale analysis scheme is proposed for damage modeling of composite laminates, sandwich structures, and stiffened plates relying on capabilities of the parametric HFGMC and isogeometric RZT{3,2} formulations. The Ramberg Osgood (RO) model is incorporated into the micromechanics model to reflect polymer matrix material nonlinearities on the overall homogenized composite behavior. Carbon fibers are assumed to behave in a linear transversely isotropic manner. The higher order RZT{3,2} theory employed at the macro level facilitates efficient applicability of the model to thick composite laminates and soft core sandwiches. On the other hand, it generates all three-dimensional stress components and thus ensures dimensional consistency between micro and macro levels. Numerical discretization and prediction of RZT{3,2} kinematic variables are enabled by performing NURBS based isogeometric analysis (IGA) thereby enhancing modeling efficacy to a significant degree. Soft core plasticity and failure in the composite are evaluated at the macro level through the RO model and Hashin criteria, respectively. Applicability of the method is presented for thin and thick flat composite and sandwich laminates; and further extended to stiffened plates via developing a multipatch formulation. A comprehensive validation of our analysis is conducted by comparing the results with established benchmarks from the literature, experimental data, and three-dimensional finite element method (3D-FEM) simulations. Initially, a moderately thick, simply supported square laminate under transverse loading is examined, a common verification benchmark. Then, results from standard mechanical tests, including tensile, shear, and four-point bending tests on thin laminates, followed by experiments on moderately thick sandwich structures subjected to four-point bending, are presented. Finally, the analysis is extended to a stiffened plate under uniform pressure, demonstrating the method’s accuracy and applicability across diverse structural configurations.

Different characteristics between acute and delayed proximal junctional failure in elderly patients undergoing corrective surgery for adult spinal deformity: comparative analysis of risk factor, failure mode, and clinical consequences

Background contextWhile numerous studies have been conducted on proximal junctional failure (PJF), the clinical significance of acute and delayed PJF remains poorly understood. PurposeThe primary object of this study is to investigate the risk factors separately for acute and delayed PJF. Secondly, we aim to assess the incidence of each failure mode and their clinical consequences in relation to acute and delayed PJF. Study design/settingRetrospective comparative study. Patient samplePatients aged ≥60 years who underwent deformity correction with ≥5-level fusion to sacrum. Outcome measuresRisk factor, failure modes, and patient-reported outcome measure (PROM) MethodsAcute PJF is defined as PJF occurring within 6 months, while delayed PJF occurring after 6 months. Risk factors were analyzed by comparing various clinical and radiographic parameters among three groups: no, acute, and delayed PJF groups. The failure modes, including soft tissue failure, vertebral fracture, fixation failure, and myelopathy, were compared among these groups. The clinical subsequences after PJF development were evaluated by assessing the change in proximal junctional angle (PJA), revision rate, and patient-reported outcome measure (PROM). ResultsA study cohort of 363 patients was included in the analysis. Among them, 156 patients experienced PJF, with 87 patients (55.8%) in the acute PJF group and 69 patients (44.2%) in the delayed PJF group. Multivariate analyses showed that older age (Odds ratio [OR] = 1.057, 95% confidence interval [CI] = 1.002 – 1.118), osteoporosis (OR=2.149, 95% CI = 1.074 – 4.300), high American Society of Anesthesiology ASA score (OR=2.150, 95% CI = 1.089 – 4.245), and overcorrection relative to the age-adjusted pelvic incidence - lumbar lordosis target (OR=4.031, 95% CI = 1.962 – 8.280) were identified as risk factors for the development of acute PJF. On the other hand, a high body mass index (OR=1.150, 95% CI = 1.049 – 1.251) and an uppermost instrumented vertebra located at ≤ T10 (OR=2.267, 95% CI = 1.205 – 4.268) were found to be associated with delayed occurrence of PJF. No radiographic parameters were found to be related to the development of delayed PJF. In terms of failure modes, vertebral fracture and fixation failure were more commonly observed in acute PJF, while soft tissue failure and myelopathy were more predominant in delayed PJF. The clinical course was more aggressive in the acute PJF group compared to the delayed PJF group, as evidenced by a greater increase in PJA, a higher revision rate, and worse PROM. ConclusionsThis study demonstrated different risk factors between the acute and delayed PJF. It was found that overcorrection relative to the age-adjusted PI-LL target increased the risk of acute PJF, but had no impact on the development of delayed PJF. Therefore, a different surgical strategy needs to be established to mitigate both acute and delayed PJF.

Soft rock deformation and failure modes under principal stress rotation from roadway excavation

Soft rock deformation and failure modes under principal stress rotation from roadway excavation

Novel condition-based opportunistic maintenance policy for series systems with dependent competing failure processes

This paper investigates a novel condition-based opportunistic maintenance model for a two-component series system. The system comprises two non-identical components, that is, Component 1 and Component 2, suffering from shocks with different intensities. The two components are subject to dependent competing failure processes, that is, soft and hard failures. The component fails whichever type of failure process occurs. At each inspection, the replacement decision for components is made according to the condition of both components. In addition, when Component 1 is preventively replaced and Component 2 reaches the opportunistic maintenance threshold, opportunistic maintenance (OM) is implemented on Component 2. The optimal inspection interval, preventive replacement (PR) threshold, and OM threshold are derived by minimizing the long-run expected maintenance cost rate. Finally, the superiority of the proposed maintenance model is verified by an illustrative example.

Cochlear reimplantation outcomes over 20 years: Expertise in reimplantation surgery and auditory-speech rehabilitation

ObjectivesThe aim of this study was to present an institution's experience with cochlear reimplantation (CRI), to assess surgical challenges and post-operative outcomes and to increase the success rate of CRI. Study designRetrospective single-institution study. SettingTertiary medical center. MethodsWe retrospectively evaluated data from 76 reimplantation cases treated in a tertiary center between 2001 and 2022. Clinical features including etiology of hearing loss, type of failure, surgical issues, and auditory speech performance were analyzed. Categorical Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scores were used to evaluate pre- and post-CRI outcomes. ResultsThe CRI population comprises of 7 patients from our institute,69 referred patients from other centers. Device failure was the most common reason (68/76, 89.5 %) for CRI; in addition, there were 7 medical failures and 1 had both soft device failure. Medical failures included flap rupture and device extrusion, magnet migration, auditory neuropathy, leukoencephalopathy, foreign-body residue and meningitis. In 21/76 patients, the electrode technology was upgraded. The mean time to failure was 0.58–13 years, with a mean of 4.97 years. The mean (± SD) CAP and SIR scores before and after CRI were 5.2 ± 1.2 versus 5.5 ± 1.1 and 3.4 ± 1.1 versus 3.5 ± 1.1, respectively. Performance was poor in six patients with severe cochlear malformation, auditory nerve dysplasia, leukoencephalopathy, and epilepsy. ConclusionCRI surgery is a challenging but relatively safe procedure, and most reimplanted patients experience favorable postoperative outcomes. Medical complications and intracochlear damage are the main causes of poor postoperative results. Therefore, adequate preoperative preparation and atraumatic CRI should be carried out for optimal results.

Functional Outcomes and a Review of Management Options for Revision Shoulder Arthroplasty.

Increase in the number of primary shoulder arthroplasty has led to an increase in the number of revisions which presents many complex challenges and often has inferior outcomes. Data was collected retrospectively, and patients were classified using Dines classification. Comprehensive case reviews were done to identify preoperative and intra-operative challenges. The primary outcome measure was Oxford shoulder score (OSS). The secondary measures were range of motion (ROM) and patient satisfaction (very satisfied, satisfied, not satisfied or worse). A total of 32 patients were identified with a mean age of 67.64 years and the most common cause of revision was a combination of bone and soft tissue failure (39.3%). All patients (n=8) with hemiarthroplasty had rotator cuff deficiency while patients with resurfacing had both rotator cuff failure and bony erosion. Four patients needed a proximal humeral osteotomy and six patients needed allograft reconstruction of the glenoid for bone loss. Twenty-one shoulders were revised to reverse total shoulder arthroplasty (TSA), 2 to anatomical TSA and 5 were left with cement spacer in situ. Mean duration of follow-up was 41.6 months. Mean OSS at the last follow-up was 26.88 with statistically significant improvement in ROM. There was no statistical difference in clinical outcomes (p>0.05) based on the type of primary prosthesis or cause of revision. A total of 70% patients were pain free. Patients with infection had inferior outcomes with a mean OSS of 17. Management of patients with failed shoulder arthroplasty is often challenging but has good clinical outcome except in infections.

Kinematics, kinetics, and new insights from a contemporary analysis of the first experiments to produce cervical facet dislocations in the laboratory.

The first experimental study to produce cervical facet dislocation (CFD) in cadaver specimens captured the vertebral motions and axial forces that are important for understanding the injury mechanics. However, these data were not reported in the original manuscript, nor been presented in the limited subsequent studies of experimental CFD. Therefore, the aim of this study was to re-examine the analog data from the first experimental study to determine the local and global spinal motions, and applied axial force, at and preceding CFD. In the original study, quasistatic axial loading was applied to 14 cervical spines by compressing them between two metal plates. Specimens were fixed caudally via a steel spindle positioned within the spinal canal and a bone pin through the inferior-most vertebral body. Global rotation of the occiput was restricted but its anterior translation was unconstrained. The instant of CFD was identified on sagittal cineradiograph films (N = 10), from which global and intervertebral kinematics were also calculated. Corresponding axial force data (N = 6) were extracted, and peak force and force at the instant of injury were determined. CFD occurred in eight specimens, with an intervertebral flexion angle of 34.8 ± 5.6 degrees, and a 3.1 ± 1.9 mm increase in anterior translation, at the injured level. For seven specimens, CFD was produced at the level of transition from upper neck lordosis to lower neck kyphosis. Five specimens with force data underwent CFD at 545 ± 147 N, preceded by a peak axial force (755 ± 233 N) that appeared to coincide with either fracture or soft tissue failure. Re-examining this rich dataset has provided quantitative evidence that small axial compression forces, combined with anterior eccentricity and upper neck extension, can cause flexion and shear in the lower neck, leading to soft tissue rupture and CFD.

Convolutional preprocessing Transformer-based fault diagnosis for rectifier-filter circuits in nuclear power plants

Rectifier-filter circuit, as a vital electronic component in nuclear power plants (NPPs), serves the role of converting alternating current into smooth direct current. Affected by intense radiation environmental factors and variable operating profiles, the rectifier-filter circuit is subject to degradation and soft failures, namely, a derated circuit performance but not yet to failure. It is urgent to diagnose the soft failures of the rectifier-filter circuit, so as to ensure the safe operations of NPPs. In this article, an ensemble empirical mode decomposition (EEMD) algorithm is first employed to decompose the three-phase current signals and electrical signals of electronic components. The decomposed signals are fed into a convolutional preprocessing Transformer (CPT) to deeply extract the fault features of the rectifier-filter circuit. Specifically, the multi-directional, multi-scale, and extremely sensitive long-range time-dependent features in the EEMD feature data are extracted by the multi-head attention mechanism of the Transformer. A deep Softmax classifier is, then, devised to reduce the feature dimensionality and identify the soft fault modes of the rectifier-filter circuit. The fault simulation of the rectifier-filter circuit is conducted, and a real case experiment and multiple comparative studies are conducted to validate the effectiveness and diagnosis accuracy of the CPT-based method.

Digital-twin-assisted meta learning for soft-failure localization in ROADM-based optical networks

Reconfigurable optical add/drop multiplexer (ROADM) nodes are evolving towards high-degree architectures to support growing traffic and enable flexible network connectivity. Due to the complex composition of high-degree ROADMs, soft failures may occur between both inter- and intra-node components, like wavelength selective switches and fiber spans. The intricate ROADM structure significantly contributes to the challenge of localizing inter-/intra-node soft failures in ROADM-based optical networks. Machine learning (ML) has shown to be a promising solution to the problem of soft-failure localization, enabling network operators to take accurate and swift measures to overcome such challenges. However, data scarcity is a main hindrance when using ML for soft-failure localization, especially in the complex scenario of inter- and intra-node soft failures. In this work, we propose a digital-twin-assisted meta-learning framework to localize inter-/intra-node soft failures with limited samples. In our proposed framework, we construct several mirror models using a digital twin of the physical optical network and then generate multiple training tasks. These training tasks serve as pretraining data for the meta learner. Then, we use real data for fine-tuning and testing of the meta learner. The proposed framework is compared with the rule-based reasoning method, transfer-learning-based method, and artificial-neural-network-based method with no pretraining. Experimental results indicate that the proposed framework improves localization accuracy by over 15%, 33%, and 54%, on average, compared to benchmark approaches, respectively.

Reliability assessment models for competing failure processes with two types of correlative thresholds

AbstractThe two dependent competing risks are soft failure due to aging degradation and fragmentation caused by shocks and hard failure due to spring breakage caused by the same shock process. Considering the complexity of the product itself and the instability of the working environment, this study proposed a generalized reliability model for systems experiencing dependent competing failure processes (DCFPs) of degradation and random shocks, which considered two kinds of DCFP: (1) shock process could affect soft failure thresholds; (2) degradation process could affect hard failure thresholds. In case (1), we considered the effect that a cumulative number of shocks above a certain magnitude could have on the change in the soft failure threshold. In case (2), we considered not only the shock process's impact on the soft failure threshold but also the total degradation (including continuous degradation and sudden degradation caused by shock) on the hard failure threshold. The model captures the features that the shocks experienced by the system affect the degradation process, accelerating the system degradation and causing soft failures; the degradation process of the system affects the shock process, making the system more susceptible to failure from external shocks. Finally, an example using micro‐electro‐mechanical systems devices illustrates the effectiveness of the proposed approach with sensitivity analysis.

Reliability analysis method of competitive failure processes considering the coupling effect of multiple shock processes and degradation process

AbstractDuring the operational phase, complex systems are subject to various shocks, both random and continuous degradation. This coupling effect poses significant challenges for reliability assessment. The proposed method aims to provide a clear and objective evaluation of the system's reliability. In this paper, we propose a competitive failure reliability analysis method that considers the coupling effect of multiple shock processes and degradation processes. The random shocks are subdivided into external and internal shocks. The degradation increment is mainly influenced by external shocks, whereas internal shocks affect the degradation rate. The combined effect of these two shock processes accelerates the failure processes. Additionally, two different shock models are combined to create an extreme‐cumulative shock model to assess the impact of various shock processes and the degradation process on system reliability. The analysis examines the coupling effect between the degradation process and shock processes to explore the influence law between hard failure and soft failure. Subsequently, the reliability modeling of competitive failure processes is completed. Finally, practical case studies demonstrate the effectiveness and practicality of the proposed method.

Comparison of oncological and functional outcomes in Lower-limb osteosarcoma pediatric patients: a large single-center retrospective cohort study.

Treating pediatric osteosarcoma in long bones is challenging due to skeletal immaturity, which restricts the generalizability of insights derived from adult patients. Are there disparities in outcomes? How should surgical protocols be tailored for children of varying ages? What are the specific postoperative complications? A large single-center retrospective cohort study of 345 patients under 14 years old with lower-limb osteosarcoma treated in our department since 2000 was conducted to address these inquiries. A retrospective analysis of 345 pediatric patients with lower-limb osteosarcoma admitted to our department between 2000 and 2019 was conducted. Clinical and functional outcomes were compared based on age groups, surgical methods, type of prosthesis, and primary tumor location. Patients were divided into the low-age group (≤10y old) and the high-age group (>10y old). Overall survival rate (OS), progressionfree survival rate (PFS), and prosthesis survival rate were assessed using Kaplan-Meier curves, nonparametric survival analysis (log-rank test), and Univariate cox regression were used for comparison. The incidence of complications, local relapse rate (LRR), metastasis rate, final limb-salvage, and amputation rate, and Musculoskeletal Tumor Society (MSTS) score of different independent groups were further evaluated using χ2 test or Fisher's exact test, and t -test was employed to evaluate the measurement data. The average age of the patients was 11.10±2.32 years ranging from 4 to 14y, with an average follow-up duration of 48.17 months. The 5, 10, and 15-year OS rates were 50.3%, 43.8%, and 37.9%, respectively. The progression-free survival rate was 44.8% at 5 years and 41.1% at 10 years. The final limb salvage rate was 61.45%, while the final amputation rate was 38.55%. The low-age group had a higher amputation rate compared with the high-age group (48.00% vs. 33.18%, P =0.009). The overall LRR was 9.28%, and the incidence of metastasis was 28.99%. The LRR of the limb-salvage group was higher than the amputation group ( P =0.004). The low-age group experienced more prosthesis-related complications than the high-age group ( P =0.001). The most common prosthesis-related complication in the low-age group was soft-tissue failure, while the periprosthetic infection was most frequent in the high-age group. The high-age group had a higher cumulative prosthesis survival compared with the low-age group ( P =0.0097). Modular prosthesis showed better MSTS scores and higher cumulative prosthetic survival than expandable prosthesis in pediatric patients ( P <0.05). Limb preservation in pediatric patients becomes increasingly efficacious with advancing age, while consideration of amputation is warranted for younger patients. The prevailing postoperative complications associated with prosthesis encompass soft tissue failure and periprosthetic infection. Younger patients diagnosed with lower limb osteosarcoma exhibit a heightened amputation rate and a greater incidence of prosthesis-related complications.

Limb Salvage and Pelvic Reconstruction With Endoprosthesis After Pelvic Tumor Resection: A Narrative Review.

Periacetabular defects following tumor resection present formidable challenges in reconstruction and continue to pose clinical difficulties. Historically, treatment approaches leaned towards hindquarter amputation; however, due to associated morbidities and functional limitations, limb-sparing procedures gained prominence in the 1980s. Nevertheless, the intricacies of pelvic anatomy and the imperative of achieving wide surgical margins while preserving essential structures make pelvic tumor resection and subsequent reconstruction inherently complex. Various reconstruction modalities have been explored, including non-vascularized fibular grafts and prosthetic implants. Among these options, the LUMiC® endoprosthesis stands out as a promising solution for pelvic reconstruction post-tumor resection. Characterized by a modular design featuring a hydroxyapatite-coated stem and acetabular cup, this device has shown favorable implant survival rates in studies, despite encountering complications primarily associated with soft tissue failure, dislocation, and infection. Notably, the incidence of complications varies across studies. The Henderson classification system delineates these complications, encompassing soft tissue issues, aseptic loosening, periprosthetic fractures, infections, and tumor recurrence. Despite the encouraging functional outcomes associated with the LUMiC® endoprosthesis, it is not immune to limitations. Concerns persist regarding complications such as dislocation and infection, underscoring the imperative for further research to evaluate the long-term durability and reliability of this reconstructive approach. Moreover, advancements in surgical techniques, perioperative management, and the advent of navigation-assisted procedures hold promise for enhancing outcomes and mitigating complication rates in pelvic reconstruction surgeries.

Improving the sensitivity of cochlear implant integrity testing by recording electrode voltages with surface electrodes

IntroductionIdentification of faults with the internal, implanted, part of a cochlear implant presents a challenge for the cochlear implant community. Advanced Bionics Ultra V1 devices are vulnerable to moisture ingress, a hard failure, resulting in reduced volume and clarity for the recipient. The manufacturer uses a trans-impedance test “Electrical Field Imaging” to identify faulty Ultra V1 devices but reports the sensitivity of the test to be only 70–90%.MethodsIn our clinic we performed Electrode Voltage measurements with surface electrodes and have compared the two tests. Electrical Field imaging and Electrode Voltage (EV) measurements were available for 65 devices. Surface electrodes were attached to the earlobes and forehead and potentials measured in three montages: ipsilateral earlobe and forehead, contralateral earlobe and forehead, and both earlobes; voltages were extracted and relative voltages across the array were calculated.ResultsRelative EV were compared for the two earlobes montage and fitted to a third order polynomial function. A new criterion for identifying faulty devices was derived, with a deviation of &amp;lt; 6% for individual electrodes for normally functioning devices or ≥6% for faulty devices. All devices which were normal according to the new criterion (N = 15) had a normal electrical field imaging test, whilst 17/50 devices which were abnormal had normal electrical field imaging and 33/50 which were abnormal had abnormal electrical field imaging.DiscussionThe REVs test was well-tolerated and carried out in a routine cochlear implant clinic. Together with test sensitivity and reliability this may make it a new routine assessment tool to aid in distinguishing hard and soft failures.