Metal Debris Research Articles

Quantification and severity grading of femoral vessel compression by adverse reactions to metal debris in metal-on-metal total hip arthroplasty.

Metal-on-metal (MoM) total hip arthroplasty (THA) may cause adverse reactions to metal debris (ARMD). ARMD causing femoral vessel compression with serious complications has been described in case reports, but the rate of compression by ARMD is not known. This study aims to investigate the rate, and quantify the severity, of femoral vessel compression in MoM hips with ARMD lesions. Patients under surveillance for MoM THA investigated with MRI were studied. In patients with confirmed ARMD, femoral artery (FA) and vein (FV) diameters were measured at the point of maximal compression and compared to contralateral vessels. The primary outcome measure was presence or absence of compression. Cases were then classified by compression ratios. Secondary outcome measures were rates of deep vein thrombosis, revision surgery and time to ARMD from index procedure. MRI scans for 436 patients with MoM THA were screened. Of these, 211/436 (48.4%) showed evidence of ARMD. Measurements were obtained on 133/211 (63.0%) patients. The FV was compressed in 102/133 (76.7%) and FA in 58/133 (43.6%), while 31/133 (23.3%) patients had no compression. In FVs, 42 demonstrated mild compression, 39 moderate and 21 severe. In FAs, none were severely compressed, 6 were moderate and 52 showed mild compression. There were 3 DVT cases, 2 in patients with moderate FV compression and 1 in patients without FV compression. Revision rates were highest in patients with severe FV compression (14/21, 66.7%). The mean time for MRI-diagnosed ARMD from index procedure was 8 years and 1 month (range 11 months-14.5 years). Extra-luminal compression of the femoral vessels was found in >75% of patients with ARMD. Although it is not clear whether revision for femoral vessel compression is required, quantification of FV compression may be useful for surgeons and radiologists considering revision for ARMD.

Removal of SUS304 fine particles transformed into martensite by the high gradient magnetic separation under dry condition

The interfusion of impurities such as metallic wear debris has been a major issue in the manufacturing process of foods, medicines and industrial products. Such debris originates with wearing of stainless-steel pipe joints or mechanical moving parts. Since the debris shows ferromagnetic properties by undergoing the strain-induced martensitic transformation of non-magnetic SUS304 (X5CrNi18-10), the magnetic separation system is much efficient to remove such debris from raw materials. In order to study the magnetic separation properties for the martensitic transformation fine particles, the several kinds of magnetic powder with different magnetization were prepared by controlling the amount of martensitic transformation by heat-treating SUS304 powders. The magnetic separation performance was evaluated by the high gradient magnetic separation (HGMS) experiments using the multilayer unidirectional magnetic wire filter under dry condition. The experimental results and FEM particle trajectory simulations revealed that the SUS304 powders transformed into martensite were removed at high speed of 0.1 m/s by the superconducting HGMS in a relatively low magnetic field.

Evolución de los niveles séricos de cromo y cobalto tras el empleo de un vástago con cuello modular en la artroplastia total de cadera primaria

Introduction and objectivesModular neck primary stems were introduced with the theoretical advantage of restoring the hip anatomy more precisely. However, the presence of a second junction has been associated with increased corrosion and release of metal debris. The objective of our study is to quantify of chromium and cobalt serum values, and to analyze their temporal evolution during five years. Material and methodsWe present a prospective series of 61 patients who underwent primary total hip arthroplasty by implantation of the HMAX-M® stem (Limacorporate, San Daniele, Italy). Serum chromium and cobalt determinations were performed at six months, two years and five years. ResultsOur series shows a progressive elevation in chromium levels with a significant difference between chromium values at six months (0.35±0.18) and five years (0.52±0.36), P=.01. Regarding cobalt, a statistically significant elevation is observed between six months and two years and a subsequent stabilization of values between two and five years, with a cobalt mean at six months (1.17±0.8) significantly lower than at two (2.63±1.76) and five years (2.84±2.1), P=.001. ConclusionElevated serum cobalt levels have been observed in patients who underwent modular neck stem implantation. The results obtained in this study have limited the use of stems with a modular neck in our clinical practice.

Metal debris release is commonly seen from explanted total ankle replacements

This study aimed to characterise the damage mechanisms present on the metal components used in various contemporary total ankle replacements. Twenty-seven explanted total ankle replacements comprising 8 different designs (3 fixed bearing and 5 mobile bearing) were analysed using various explant analysis techniques. Pitting and scratching were the most commonly observed wear features. Microscopic analysis revealed metallic pitting on 52% of tibial components and 95% of talar components. Pitting was identified on more cobalt-chromium than titanium alloy tibial components (63% versus 0%). Non-contact profilometry confirmed the presence of pitting, with significant (p < 0.05) differences in the measured average surface roughness values of pitted and unpitted areas for tibial and talar components. There was macroscopically visible sliding plane scratching, indicating the presence of hard third body particles, on 78% of talar components. Changes to the non-articulating surfaces coatings in terms of coating loss and/or changes in reflectivity was identified visually on 80% of metal components. Scanning electron microscopy with energy dispersive X-ray spectroscopy identified metallic embedded debris in 19% of polyethylene inserts. This explant study demonstrates the release of metal debris from both the metallic tibial and talar component articulating surfaces and non-articulating surface coatings of various contemporary total ankle replacements. Metal particulate debris release from total ankle replacements may be more common than previously recognised. Metal debris should be considered in further study into the aetiology of failed total ankle arthroplasty.

Experimental investigation on debris bed formation from metallic melt coolant interactions

Motivated by risk quantification of severe core meltdown accidents which may occur light water reactors, an extensive DEFOR (DEbris FORmation) test series with various molten oxidic materials was conducted previously at Royal Institute of Technology to investigate the characteristics of debris beds formed from oxidic melt-water interactions, which are important to the coolability of debris beds and thus the retention of core melt. Yet, little attention has been paid to metallic melt which exist in the core melt. The present study is intended to fill in the knowledge gap, i.e., to characterize metallic melt-water interactions when a melt jet falls into a deep water pool. Nine DEFOR-M tests are carried out to clarify the effects of melt jet diameter, free fall height and water pool depth on metallic debris formation characteristics. Molten tin of 20 kg is employed as the simulant of metallic melt. A melt sensor and a mass sensor are installed to detect the discharging period of coherent jet and the mass accumulation of debris bed, respectively. A high-speed camera is applied to record the process of jet breakup, debris fragmentation and solidification, and debris bed formation. The experimental results show that the water pool depth has a significant influence on steam explosion and debris bed formation characteristics. Moreover, the jet breakup length is sensitive to jet diameter and free fall height. Finally, the features of metallic debris beds are compared with those of oxidic ones in respects of debris bed's configuration and porosity, particles' morphology and size distribution.

Constrained metal-on-metal hip arthroplasty: ever heard of a50-year survival story?

The history of total hip arthroplasty dates back to the first half of the twentieth century. Data on hip endoprostheses implanted during the 1960s and 1970s suggest widely varying survival rates of the prosthesis. Acase of apatient who underwent total hip arthroplasty in 1972 using aSivash prosthesis, developed in 1956 in the former Soviet Union, is presented in this article. The prosthesis has remained unrevised in the patient's body for 50years and he continues to be widely free of implant-related symptoms. Despite the constrained metal-on-metal design of the implant, which can lead to adverse reactions to metal debris, no elevated systemic metal ion levels were detected. The likelihood of encountering patients with prosthesis survival beyond 50years is still rare. Nevertheless, changing demographics and the steadily improving designs and materials of hip endoprostheses may likely result in such cases.

Strategies for fixation of periprosthetic fragility fractures of the neck of femur below a well-functioning hip resurfacing arthroplasty: A case-series

IntroductionMetal-on-metal Hip Resurfacing (HR) was performed in many young individuals as it conserved bone stock and had low wear rates, before it became less popular due to the detection of Adverse Reactions to Metal Debris. As such, many patients in the community have well-functioning HRs and as they age, the incidence of fragility fractures of the neck of femur around the existing implant is expected to increase. These fractures are amenable to surgical fixation as adequate bone stock remains in the head of the femur and the implants are well fixed. Case-seriesWe present a series of six cases which were treated by fixation using locked plates (3), dynamic hip screws (2) and cephalo-medullary nail (1). Four cases achieved clinical and radiographic union with good function. One case had a delayed union, though union was finally achieved at 23 months. One case had an early failure necessitating revision to a Total Hip Replacement after 6 weeks. DiscussionWe highlight the geometrical principles of placing fixation devices under an HR femoral component. We have also conducted a literature search and present details of all case reports to date. ConclusionFragility per-trochanteric fractures under a well-fixed HR with good baseline function are amenable to fixation using a variety of methods including large screw devices that are commonly used in this location. Locked plates including variable angle locking designs should be kept available if needed.

Robotic Detector with Rocker Bogie Mechanism

The Rocker Bogie Mechanism (RBM) is widely used in planetary rovers for its ability to traverse challenging terrain. However, the presence of metal debris in the terrain can pose a significant threat to the rover's mobility and instrumentation. Therefore, a metal detector integrated with the RBM is necessary to avoid any potential damage. This paper presents the design and development of a metal detector for the RBM, which includes the selection of suitable components, the development of the detection algorithm, and the integration with the RBM. The detector's performance is evaluated in both simulation and experimental settings, demonstrating the successful detection of metallic objects and their location.

Using a handheld metal detector to detect ingested hooks and other metallic objects in freshwater turtles

AbstractTurtles can be unintentionally hooked during recreational and commercial fishing operations. While hook ingestion is not always fatal, ingested hooks can harm or kill turtles by damaging soft tissues or affecting digestion. Detecting ingested hooks and other metallic debris in the field is a challenge. As such, we tested the efficacy of a handheld metal detector in detecting ingested fish hooks and incidental metallic debris in freshwater turtles in Georgia, USA. We captured 426 individual freshwater turtles representing 4 species and radiographed 106 yellow‐bellied sliders (Trachemys scripta scripta). Of 37 turtles that tested positive with a handheld metal detector, radiographs revealed 17 (46%) had ingested at least one hook, 15 (40%) had ingested an unidentifiable metal object or objects, and 5 (14%) showed no clear signs of hooks or other metallic objects. All 69 turtles that tested negative in the field and were radiographed showed no signs of metal ingestion. Accordingly, our proportion of false positives was 14% (5 of 37), false negatives (metal not detected in field but on follow‐up radiograph) were 0% (0 of 69), and our overall accuracy at detecting ingested metal with a handheld metal detector was 95% (101 of 106 radiographed turtles). Thus, handheld metal detectors may be a useful tool for detecting ingested hooks and other metallic objects in freshwater turtles.

Hip and Knee Arthroplasty: A Review of Complications and Advances in Imaging

Arthroplasty-related complications are challenging to diagnose as they often present with nonspecific signs and symptoms, and can lead to long-term morbidity if inadequately managed. The difficulty in imaging implants is compounded by its intrinsic propensity to artifacts. Strategies to reduce this include: Judicious use of the appropriate imaging modality for the relevant clinical indication; knowledge of optimizing imaging acquisition parameters; and use of metal artifact reduction (MAR) software. We review the literature on expected normal appearances of hip and knee arthroplasties, findings of arthroplasty-related complications on various imaging modalities, advances in imaging techniques, and subsequently, suggest an algorithm for painful arthroplasty assessment. Serial radiographs remain key in identifying subtle changes in component position, hardware failure, periprosthetic osteolysis, and potential for loosening, given their ready availability, high resolution, and minimal metal-related artifact. Computed tomography with MAR provides 3D assessment and information on bone stock for surgical planning and custom implants. Magnetic resonance imaging with MAR can identify complications at earlier stages, such as loosening, capsular dehiscence in instability, and periprosthetic edema in nondisplaced fractures. It has high diagnostic performance in infection (lamellated synovitis), particle disease, adverse reactions to metal debris, in addition to demonstrating impingement on neurovascular structures. Nuclear medicine imaging is used as a problem-solving tool and is valuable in its high negative predictive value. Novel imaging techniques can further reduce artifacts and improve visualization of the implant-bone interface, and machine learning can facilitate image interpretation although attaining sufficient data and clinical validation will be challenging.

Research on Detection Performance of Four-Coil Inductive Debris Sensor

The online monitoring of debris in oil can timely and accurately reflect the wear status of mechanical equipment. The inductive debris sensor based on the electromagnetic induction can effectively detect various parameters of debris. The four-coil structure-based of the sensor is theoretically introduced. The optimal coil length, the turns of the excitation coil and the turn ratio are obtained through simulation in order to improve the sensitivity of the inductive debris sensor. The effects of the excitation frequency and the movement velocity, size, position and material of the debris on the sensor output are investigated. The sensing signal recovered by coherent demodulation confirms the sensor’s effectiveness in identifying metal debris. The experiment realized the identification of iron debris with a diameter of 93.5 μm and copper debris with a diameter of 447.3 μm under the 3 mm pipe radius, providing a reference for the design of four-coil inductive debris sensor.

Evolution of morphology, microstructure and hardness of bodies and debris during sliding wear of carbon steels in a closed tribosystem

Debris generated during sliding wear of steels have an important role on tribosystem's behavior. However, the evolution of morphology, microstructure and hardness of debris and solid bodies, and their role on friction and wear is not quite evident, especially for closed tribosystems. Interrupted pin-on-disk wear tests were carried out on low, medium, and high carbon steel tribopairs, while an adaptation of the test apparatus effectively prevented debris ejection from wear track, simulating a closed tribosystem. The experiment was designed according to a repeated measures ANOVA model for multiple dependent variables that includes running-in duration, wear rates, surface hardness and their ratios, and debris size and shape. Plasticity-dominated severe wear took place in all cases, generating two types of metallic debris: flake-type via adhesion and delamination processes and, after sufficient sliding distance, cutting-type due severe shear deformation caused by the abrasive action of hard asperities. Debris were, at least, 20% softer than worn pins and disks, and provided some lubricating effect when adhered, sheared and rolled between sliding surfaces. Low carbon steel wear generated more soft and adherent debris, resulting in prolonged running-in periods. Finally, steel carbon content did not affect wear mechanisms, debris morphology (size and shape), worn surface hardness and wear rates in closed tribosytems, when a debris-flow controlled process prevails.

On the Investigation of Frequency Characteristics of a Novel Inductive Debris Sensor.

Lubricants have the ability to reduce frictions, prevent wear, convey metal debris particles and increase the efficiency of heat transfer; therefore, they have been widely used in mechanical systems. To assess the safety and reliability of the machine under operational conditions, the development of inductive debris sensors for the online monitoring of debris particles in lubricants has received more attention from researchers. To achieve a high-precision, high-efficiency sensor for accurate prediction on the degree of wear, the equivalent circuit model of the sensor coil has been established, and its equations discovering the relationship between the induced voltage and excitation frequency have been derived. Furthermore, the influence of excitation frequencies and metal debris on the magnetic flux density has been analyzed throughout the simulations to determine the sensor magnetic field. In order to identify a frequency range suitable for detecting both ferrous and non-ferrous materials with a high level of sensitivity, the analytical analysis and experiments have been conducted to investigate the frequency characteristics of the developed inductive debris sensor prototype and its improved inspection capability. Moreover, the developed inductive debris sensor with the noticeable frequency characteristics has been assessed and its theoretical model has been also validated throughout experimental tests. Results have shown that the detection sensitivity of non-ferrous debris by the developed sensor increases with the excitation frequency in the range of 50 kHz to 250 kHz, while more complex results for the detection of ferrous debris have been observed. The detection sensitivity decreases as the excitation frequency increases from 50 kHz to 300 kHz, and then increases with the excitation frequency from 300 kHz to 370 kHz. This leads to the effective selection of the excitation frequency in the process of inspection. In summary, the investigation into the frequency characteristics of the proposed novel inductive debris sensor has enabled its broad applications and also provided a theoretical basis and valuable insights into the development of inductive debris sensors with improved detection sensitivity.

Long-Term Outcomes of Articular Surface Replacement (ASR) Implant in Hip Arthroplasty: A Single Institution Review.

Various metal-on-metal (MoM) total hip replacements (THRs) have been found to have high short-term failure rates due to adverse responses to metal debris (ARMD). As a consequence, several low-performing THRs have been removed off the market. The purpose of this research was to look at the at least five-year outcomes of patients who had MoM hip arthroplasty at our institution. In one specialised centre between 2007 and 2008, 24 Articular Surface Replacement (ASRTM, DePuy, Warsaw, IN, USA) MoM THRs (in 24 patients, mean age: 56.4 years) were implanted. DePuy ASR hip prosthesis for osteoarthritis or hip fractures were employed in the THR system. All patients were summoned back for a clinical assessment, and imaging was done as needed. The average period of follow-up was 8.0 years (6.0-10 years). In all, eight instances (33.3%) were discovered to have pseudotumors, four hips (16.7%) were revised, and one (4.1%) was operated for ARMD. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Oxford ratings improved statistically significantly five years after surgery in all three areas of pain, disability, and stiffness; however, there was no statistically significant change in the 36-Item Short Form Survey (SF-36) (mental) score. MoM hip arthroplasty had a greater revision incidence at five years in our group, presumably owing to the adoption of a smaller femoral head size.

Theoretical and simulation analysis on the spatial resolution of magnetic metal debris sensors

Inductive debris sensor is becoming increasingly important in online oil debris detection. This work proposes a new criterion for evaluating the performance of an inductive oil debris sensor: spatial resolution. When multiple metal particles in lubricating oil simultaneously pass through the sensor, it is vital that clear signals responding to each particle are produced. The spatial resolution is referred to the allowable distance between two particles when the sensor can accurately distinguish the particle signals. Theoretical analysis shows that spatial resolution has a relationship with the output signal of a single particle. A COMSOL model is established to simulate a coil output when two adjacent particles pass, and the output signals change with the distance between two particles, the particle size and the coil structures. Results show that the relevant factors affecting the spatial resolution, and a small coil radius can help improve the sensor’s accuracy of debris identification.

Coastal pollution analysis for environmental health and ecological safety using deep learning technique

Environmental degradation and loss of biodiversity occur widely in marine and coastal regions. The coastal ecosystems have diverse components, including mammals, invertebrates, and plants, which are now the most densely populated zones. Because of its localized interface, it is highly vulnerable to anthropogenic pollutants such as plastic debris, metal debris, volatile methyl siloxanes, and oil spills. Conventional algorithms related to coastal pollution classification face low accuracy and time consumption issues. A deep learning-based Deep Convolutional Neural Network (DCNN) is developed to overcome these issues. Initially, coastal images are collected and pre-processed using anisotropic diffusion and global histogram equalization for further processing. Anisotropic diffusion is utilized to remove the unwanted noise present in the image. Global histogram equalization is utilized to enhance the contrast level of the image. In sequence with pre-processing phase, the processed image is classified using deep learning-based DCNN to detect and analyze coastal pollution in coastal areas. In order to optimize, the weights present in the DCNN are optimally selected by using a reptile search algorithm to improve the classification performance. According to the experimental study, the proposed approach achieves 97.2% correctness, 2.8% error, 96% precision, 95.4% recall, 96% specificity, and 96.5% f1-score. Therefore, the developed approach attains better performance compared to other existing approaches. This prediction model helps detect coastal pollution in coastal areas to protect ecological safety and environmental health.

Machining of nickel-based super alloy inconel 718 using alumina nanofluid in powder mixed electric discharge machining

Inconel 718 is a nickel-based superalloy with exceptional mechanical qualities, including high tensile and impact strength, as well as good oxidation and corrosion resistance. EDM is widely used to cut hard materials of this type by common parameters affecting spark, current, duty cycle etc, whereas MRR, SR can be greatly improved by using sufficient fluid properties of the dielectric. Incorporation of alumina nanoparticles with deionized water may improve machining performance, with no prior research on machining characteristics of Inconel 718 using alumina nanofluid in EDM. The machinability of Inconel 718 via the electrical discharge machining process, as well as the performance of alumina nanofluid as a dielectric medium, have been evaluated using deionized water with a concentration of 0.5%. In this study, based on the effect of various input parameters such as and on the MRR, TWR and SR, and the RSM has been used to conduct the experiments. A maximum MRR of 0.048 g min−1, a TWR of 0.00632 g min−1 and an SR of 3.271 μm are achieved. Overall, the use of alumina nanofluid can improve machining performance in EDM, due to the reduction of abnormalities such as crack formation and molten metal debris in the machined surface of Inconel 718.

Damage analysis of retrieved BioloxⓇdelta components used in hard and soft bearings.

This retrieval study included 43 Biolox delta explants (18 CoC, 25 CoP). Implants were examined macroscopically, whereby damage was evaluated using a semi quantitative scoring system. Confocal microscopy was used to examine wear related damage patterns of the articulating surfaces. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) was used to analyze wear marks on the implant surface and wear debris in periprosthetic tissue samples. Raman spectroscopy and X-ray diffraction (XRD) were used to quantify monoclinic zirconia fractions. On all components, in vivo wear resulted predominantly in different damage patterns caused by metal transfer. In CoC bearings stripe wear was additionally detected, and some implants underwent severe damage due to component breakage. The wear scores were higher for CoC components, with no differences between the scores for CoC heads and liners. Wear features caused comparable roughening on implants from CoC and CoP bearings. SEM studies demonstrated that most wear marks were caused by metal debris released from implant components. Grain pull-out was observed in stripe wear regions. Monoclinic phase shift was observed in a similar quantity on components from CoP and CoC bearings. The increase of monoclinic zirconia content around metal deposits was minimal and was more pronounced in areas of stripe wear. The results of this study indicate, that ZTA components in general undergo minimal wear in both, CoC and CoP bearings, however, it is more pronounced in the former. Metal deposits, as the most common wear feature, have no significant effect on monoclinic phase transition. STATEMENT OF SIGNIFICANCE: In this paper, we classify all damage patterns macroscopically according to an established scoring system and assess them regarding surface roughness (confocal microscopy) and monoclinic phase content (Raman spectroscopy) in order to derive the severity for patients. We compare hard-hard and hard-soft bearings and relate damage patterns with metal transfer based on SEM/EDS examinations. Furthermore, we work out correlations between patient-specific data, cause of revision and the physical condition of each individual sample Our cohort consists of 43 Biolox delta retrievals, a comparatively large quantity. In addition, we address current topics such as metal transfer and, based on the classification of damage patterns, provide incentives and/or meaningful focal points for further research.

Functionalized Cortical Bone-Inspired Composites Adapt to the Mechanical and Biological Properties of the Edentulous Area to Resist Fretting Wear.

Dental implants with long-term success of osseointegration have always been the goal, however, difficulties exist. The accumulation of fretting damage at the implant-bone interface often gets overlooked. Commonly used titanium is approximately 7-fold harder and stiffer than cortical bone. Stress shielding caused by the mismatching of the elastic modulus aggravates fretting at the interface, which is accompanied by the risk of the formation of proinflammatory metal debris and implant loosening. Thus, the authors explore functionalized cortical bone-inspired composites (FCBIC) with a hierarchical structure at multiple scales, that exhibit good mechanical and biological adaptivity with cortical bone. The design is inspired by nature, combining brittle minerals with organic molecules to maintain machinability, which helps to acquire excellent energy-dissipating capability. It therefore has the comparable hardness and elastic modulus, strength, and elastic-plastic deformation to cortical bone. Meanwhile, this cortical bone analogy exhibits excellent osteoinduction and osseointegration abilities. These two properties also facilitate each other to resist fretting wear, and therefore improve the success rate of implantation. Based on these results, the biological-mechanical co-operation coefficient is proposed to describe the coupling between these two factors for designing the optimized dental implants.

Sensitivity and specificity for detecting pseudotumors in patients with hip resurfacing arthroplasty, metal-on-metal or metal-on-polyethylene total hip arthroplasty-MRI versus ultrasonography performed by an orthopedic surgery resident.

Metal artifact reduction sequence magnetic resonance imaging (MRI) scan is a common method to detect adverse reaction to metal debris in total hip arthroplasty (THA). It might be quicker and cheaper if ultrasonography (US) could screen for the need for an MRI. However, both require trained personnel. We aimed to investigate the sensitivity and specificity of US for detecting pseudotumors (PT) when performed by an orthopedic surgery resident compared to MRI. We also investigated the sensitivity and specificity of US to detect PTs in obese and non-obese patients. We examined 205 patients with hip resurfacing arthroplasty, metal-on-metal or metal-on-polyethylene THA with both MRI and US. US was performed by an orthopedic surgery resident who was trained according to a standardized training program in musculoskeletal US. Results from MRI were used as gold standard. US had a sensitivity of 0.92 (95% CI 0.81-0.98) and specificity of 0.94 (95% CI 0.89-0.97) for detecting PT. It had a positive predictive value of 0.84 (95% CI 0.73-0.91) and a negative predictive value of 0.97 (95% CI 0.93-0.99). US performed similarly in obese and non-obese patients. US had a high sensitivity and specificity for detecting PT when performed by an orthopedic surgery resident. Trained orthopedic surgeons could screen for the need of an MRI scan when searching PTs.