Tear Fracture Research Articles

English

Knee injuries are common in sports and depending on the mechanism of fall, injury of different ligaments can occur. Knee injury mostly involves the anterior cruciate ligament (ACL), and is the most common injury reported on MRI. It can be associated with posterolateral corner (PLC) injury and other osseous injuries, these injuries are rarely reported as they are very complex in structure. A detail knowledge about this complex helps to evaluate the associated ligaments as well. In association with anterior cruciate ligament injuries presence of a Segond fracture indicates occurrence of a concomitant or isolated injury to the posterolateral corner injury. The evaluation of these associated injuries along with anterior cruciate ligament aids in their repair and hence improving the postoperative outcome. Three main components of posterolateral corner are divided into three layers – superficial, middle, and deep. Clinically few tests have been advised to evaluate injury of different structures of knee joint. For example - McMurray's test and Ege's test are used to evaluate meniscus, Lachman test, Anterior drawer test and Pivot Shift Test are performed to evaluate anterior cruciate ligament tear while posterior drawer test is done to evaluate posterior cruciate ligament tear. Availability of special closely coupled extremity coils, high field systems, open system & extremity units have made MRI supplemental to clinical examination and plain radiographs for virtually all suspected disorders of knee. Here, we are presenting a case of MRI of knee injury involving posterolateral corner injury with anterior cruciate ligament tear and Segond fracture. Along with anterior cruciate ligament, medial meniscus, other ligaments and osseous injury are associated as well. The other structures responsible for stabilizing the knee joints are posterolateral corner and meniscus, which when involved may need to be treated simultaneously with anterior cruciate ligament tear, for full re stabilization of knee joint. If any associated fracture is present, it has to be treated simultaneously as well.

An experimental study on the seismic behavior and replaceability of the replaceable steel shear links

The reinforced concrete columns and steel beams (RCS) composite frames have received popularity in low to moderate seismic regions due to advantages of the system. However, the poor repairable capacity and deteriorating pinched hysteretic behaviour of the traditional RCS framed structure limit the application in practice under earthquakes. This study presents a modified RCS framed structure with replaceable members aiming to enhance the energy dissipation and resilience capability. The structural configuration character and the general predetermined levels of lateral response of the proposed RCS framed structure with replaceable members is first introduced. Seven quasi-static loading tests were subsequently conducted to evaluate the seismic behavior and replaceability of the replaceable shear links. Parameters including the link length ratio, stiffener configuration and link-to-column connection were examined. The test results depicted that the specimens exhibited the shear dominated behavior. The major failure features of the shear links included web-to-stiffener weld tear, web buckling and web fracture. All tested specimen showed a stable bearing strength, large inelastic rotation capacity and excellent energy dissipation behavior. The same link length ratio of the specimens with different specialized connections presented the similar behavior. Noted that end plate and web stiffeners connection can alleviate the stress concentration on the fillet weld of the flange-to-end plate weld and optimize the performance of the shear link. The average overstrength factor and inelastic rotation capacity of the test specimens were 1.9 and 0.087 rad significantly exceeding 1.5 and 0.08 rad provided by the AISC 341-16 provisions for the EBF links, respectively. In addition, the replaceability of the specimens was evaluated underwent the entire loading process. Compared with the T-shaped and Π-shaped plate connections, replacement of the shear link with the end plate demanded the least effort and time.

State medical malpractice laws and utilization of surgical treatment for rotator cuff tear and proximal humerus fracture: an observational cohort study

BackgroundHow much does the medical malpractice system affect treatment decisions in orthopaedics? To further this inquiry, we sought to assess whether malpractice liability is associated with differences in surgery rates among elderly orthopaedic patients.MethodsMedicare data were obtained for patients with a rotator cuff tear or proximal humerus fracture in 2011. Multivariate regressions were used to assess whether the probability of surgery is associated with various state-level rules that increase or decrease malpractice liability risks.ResultsStudy results indicate that lower liability is associated with higher surgery rates. States with joint and several liability, caps on punitive damages, and punitive evidence rule had surgery rates that were respectively 5%-, 1%-, and 1%-point higher for rotator cuff tears, and 2%-, 2%- and 1%-point higher for proximal humerus fractures. Conversely, greater liability is associated with lower surgery rates, respectively 6%- and 9%-points lower for rotator cuff patients in states with comparative negligence and pure comparative negligence.ConclusionsMedical malpractice liability is associated with orthopaedic treatment choices. Future research should investigate whether treatment differences result in health outcome changes to assess the costs and benefits of the medical liability system.

Early Experience of Reverse Total Shoulder Arthroplasty in a Public Hospital in Malaysia.

Introduction:Reverse total shoulder arthroplasty provides a surgical alternative to standard total shoulder arthroplasty for the treatment of cuff tear arthropathy, arthritis and fracture sequelae. This study aimed to assess the short-term outcomes following reverse total shoulder arthroplasty for patients in a large public hospital in Malaysia.Materials and Methods:We identified and performed five primary reverse total shoulder arthroplasties between 1 May 2019 and 1 June 2020. All patients were contactable and available for analysis. Assessment of functional outcomes was performed using the Constant-Murley score, the patient satisfaction score (PSS), and imaging studies. The mean follow-up from operation to the time of reporting was 9.6 months (range, 3 to 14 months)Results:The median age for our patients was 58 years (±11.91). The most common indication for surgery was post-traumatic arthritis, followed by rotator cuff arthropathy and osteoarthritis. The mean Constant score improved from 9.0 pre-operatively to 52.3 post-operatively at a mean of 9.6 months. The majority of the patients were satisfied with the surgery as the post-operative range of motion, especially anterior elevation and abduction, improved in four of our patients and there were no short-term complications, for example, of infection or revisions, reported at the last follow-up.Conclusion:This study has shown that reverse total shoulder arthroplasty can yield good short-term outcomes for the treatment of complex shoulder problems in addition to cuff tear arthropathy. It should be considered a treatment for rotator cuff tears, severe arthritis and ≥ 3 parts proximal humeral fractures.

Influence of glenosphere diameter and lateralization on instability of reverse shoulder arthroplasty

Abstract Background Prosthetic replacement of the proximal humerus with reverse shoulder arthroplasty (RSA) is an established means of treatment. Due to its unique biomechanical characteristics, RSA can restore shoulder function to a satisfying level in the case of cuff tear arthropathy, arthritis, and fractures. However, complications are frequent in RSA, one of the more common being implant instability with dislocation. The present study investigated the influence of glenosphere diameter and metaglene lateralization using a unique test setup. Methods Seven fresh-frozen cadaveric specimens of the shoulder were thawed and dissected. The subscapularis muscle, the infraspinatus, and the three heads of the deltoid muscle were fixed to a pulley system. After implanting an RSA in different configurations (38/42 mm glenosphere with lateralization of +0 mm, +5 mm, or +10 mm), the implants were dislocated using selective muscle pull. The frequency of dislocations depending on the prosthesis configuration was documented. Results The larger glenosphere diameter of 42 mm showed less dislocations than the diameter of 38 mm (39 vs. 46). Lateralization of +0, +5 mm, and +10 mm showed 26, 29, and 30, dislocations, respectively. Dislocation via pull on the infraspinatus muscle was most frequent. None of the results reached statistical significance. Conclusion The current investigation used a novel technique for investigating the effect of lateralization and glenosphere diameter on RSA instability. Despite indicating tendencies, the present test setup could not prove the hypothesis that a larger glenosphere diameter and increased lateralization add to stability. The lack of statistical significance could be attributable to the low specimen number. The clinical significance of lateralization and glenosphere diameter should be further assessed in future biomechanical investigations.

Interpretation of emergency CT scans in polytrauma: trauma surgeon vs radiologist.

IntroductionTime is critical in the trauma setting. Emergency computed tomography (CT) scans are usually interpreted by the attending doctor and plans to manage the patient are implemented before the formal radiological report is available. This study aims to investigate the discrepancy in interpretation of emergency whole body CT scans in trauma patients by the trauma surgeon and radiologist and to determine if the difference in trauma surgeon and radiologist interpretation of emergency trauma CT scans has an impact on patient management.MethodThis prospective observational comparative study was conducted over a 6 month period (01 April–30 September 2016) at the Inkosi Albert Luthuli Central Hospital which has a level 1 trauma department. The study population comprised 62 polytrauma patients who underwent a multiphase whole body CT scans as per the trauma imaging protocol. The trauma surgeons' initial interpretation of the CT scan and radiological report were compared. All CT scans reported by the radiology registrar were reviewed by a consultant radiologist. The time from completion of the CT scan and completion of the radiological report was analysed.ResultsSince the trauma surgeon accompanied the patient to radiology and reviewed the images as soon as the scan was complete, the initial interpretation of the CT was performed within 15–30 min. The median time between the CT scan completion and reporting turnaround time was 75 (16–218) min. Critical findings were missed by the trauma surgeon in 4.8% of patients (bronchial transection, abdominal aortic intimal tear and cervical spine fracture) and non-critical/incidental findings in 41.94%. The trauma surgeon correctly detected and graded visceral injury in all cases.ConclusionThere was no significant discrepancy in the critical findings on interpretation of whole body CT scans in polytrauma patients by the trauma surgeon and radiologist and therefore no negative impact on patient management from missed injury or misdiagnosis.The turnaround time for the radiology report does not allow for timeous management of the trauma patient.

A comparative study on mechanical and rheological properties of ternary rubber blends

Polymer blends lead to producing a new class of plastics, which may have better properties than being individual. In this study, the ternary blends of natural rubber (NR)/styrene-butadiene rubber (SBR)/nitrile rubber (NBR) were prepared via melt compounding, and then the physicomechanical properties of ternary NR/SBR/NBR blends were investigated. NR content was kept constant at 30 phr, while SBR and NBR fractions were varied simultaneously. The effect of the addition of 3 phr of ultrablend 4000 as compatibilizer on the compatibility of the rubber blends was studied. The results revealed that the use of the compatibilizer has significantly resulted in the clear stability of the scorch time and the optimum cure time of the blends. Tensile strength; stress at 100%, 200%, and 300% elongations; elongation at break %; compression strength; and compression set increase with the NBR content. There was a dramatic rise in the value of swelling ratio with the decrease of NBR. Moreover, the dynamic mechanical analysis showed some shifts in glass transition temperatures for blends to higher and lower temperatures as a function of the composition, which indicates the partial miscibility between the contributing components. Scanning electron microscopy of the tear fracture surfaces indicated that incorporation of NBR in the blends resulted in better adhesion of ternary blends and improved the tensile properties of ternary blends.

Risk of knee osteoarthritis after different types of knee injuries in young adults: a population-based cohort study

ObjectivesTo estimate the risk of clinically diagnosed knee osteoarthritis (OA) after different types of knee injuries in young adults.MethodsIn a longitudinal cohort study based on population-based healthcare data from Skåne,...

Clinical Results of a Short Metaphyseal Reverse Total Shoulder Arthroplasty (RTSA) in Patients Aged 65 or Younger: Minimum 2 Years Follow Up (2–11 Years Follow Up)

To assess the outcome of a short metaphyseal rTSA in patients aged 65 or younger Reverse total shoulder arthroplasty (rTSA) are increasingly used in recent years for treatment of glenohumeral arthropathy with deficient rotator cuff. Bone preservation is becoming a major goal in shoulder replacement surgery, especially in young patients. Metaphyseal humeral components without a stem were developed to minimize bone resection and preserve bone. We evaluated 44 patients (29 F, 15 M) with a mean age of 59 years (range, 33-65 years) that underwent metaphyseal rTSA between 2006 - 2015. 17 were revisions. Indications were cuff tear artropathy, rheumathoid arthritis, primary ostheoarthritis and fracture sequelae. Constant Score (CS), Pain score, Subjective Shoulder Value (SSV) and patients’ satisfaction were used preoperatively and postoperatively with mean follow up 49 ± 25.7 months. Mean CS improved from 18.1±11.9 to 60.1±18.6 (p<0.001) (Age/sex adjusted to 83.5 ± 25.2). Pain score improved from 3.5/15 to 11.1/15. Mean active elevation 141.1°±41.9° (p<0.001), active abduction 136.8°±44.7° (p<0.001) , active external rotation 36.9°±21.4° (p<0.001) and active internal rotation 66.2°±23.1° (p<0.001). All the patients rated their shoulder as much better or better, with 68% excellent. There were no statistically significant differences between outcomes at 12 months and the last follow up; however, some further improvements were seen in almost all shoulders with time. No differences were observed between primary and revision cases. No lucencies, loosening, subsidence or stress shielding were evident radiographically. One case of grade-2 glenoid notching. 2 cases had postoperative complications. rTSA can be used with good results and high satisfaction in patients aged 65 years or younger. The use of a short metaphyseal implant that preserves the bone, allows its use in young patients as all options are preserved if any future surgeries will be needed. Good clinical and radiological results are maintained over time.

Patient-reported outcome after stemmed versus stemless total shoulder arthroplasty for glenohumeral osteoarthritis: a patient-blinded randomized clinical trial

BackgroundStemless shoulder arthroplasty systems with uncemented metaphyseal fixation have been used for glenohumeral osteoarthritis since 2004 (Hawi, et al. BMC Musculoskelet Disord 17:376, 2016). The stemless design has several theoretical advantages compared with the stemmed shoulder arthroplasty systems: restoring patients’ anatomy; preserving humeral bone stock; and few complications in component removal if the need for a revision arthroplasty arises. The purpose of the study is to compare the short-term, patient-reported outcome of stemless and stemmed total shoulder arthroplasty (TSA).Materials and methodsA randomized clinical trial will be conducted. Eighty patients with clinical and radiological signs of primary or post-traumatic glenohumeral osteoarthritis, computed tomography (CT) scan-verified adequate glenoid bone stock, and no total rupture of rotator cuff tendons verified by a magnetic resonance imaging (MRI) scan will be randomly allocated to a stemless or stemmed TSA. The primary outcome will be the Western Ontario Osteoarthritis Shoulder (WOOS) score at 12 months. Secondary outcomes are the WOOS score at three months and the Oxford Shoulder Score (OSS) and EQ-5D at 3 and 12 months. All complications, including glenoid and humeral component loosening, instability, rotator cuff tear, intraoperative and postoperative periprosthetic fracture, nerve injury, infection, deltoid injury, and symptomatic deep venous thrombosis, will be reported.DiscussionFindings will provide patients with better information about the potential benefits and harms of stemless and stemmed TSA and will assist shoulder surgeons and patients in decision-making.Trial registrationClinicaltrials.gov, NCT03877315. Registered on 13 March 2019.

Effect of Temperature on the Tear Fracture and Fatigue Life of Carbon-Black-Filled Rubber.

The mechanical behaviour of carbon-black (CB)-filled rubber is temperature-dependent. It is assumed that temperature affects the fatigue life of rubber products by changing the tear energy of the material. The static tearing behaviour and fatigue crack propagation behavior of CB-filled rubber at different temperatures were investigated in this study. The critical tear energy of the material was measured through static tear fracture tests at different temperatures; it is shown that the critical tear energy decreases exponentially with increasing temperature. A fatigue crack growth test of a constrained precracked planar tension specimen was conducted at room temperature; the measurements verify that the fatigue crack growth follows a Paris–Erdogan power law. Considering the temperature dependence of the critical tear energy, the temperature dependent fatigue crack growth kinetics of CB-filled rubber was established, and the fatigue life of the material at high temperatures was predicted based on the kinetics. The predictions are in good agreement with experimental measurements.

Microstructure evolution and mechanical properties of micro-/nano-bimodal size B4C particles reinforced aluminum matrix composites prepared by SPS followed by HER

With the advantage of micro-size and nano-size B4C particles, micro-/nano-bimodal size B4C particles have been widely used to fabricate excellent composites with high strength and ductility. In this study, micro-/nano-bimodal size B4C particles reinforced aluminum matrix composites with three different volume fractions (3%, 5% and 7%) were fabricated by spark plasma sintering (SPS) followed by hot extrusion and rolling (HER). The microstructure evolution and mechanical properties of as-SPSed, as-extruded and as-rolled composites were investigated. Results show that the microscopic electrical discharge between the particles in SPS promotes the densification of composites. The maximum relative density of as-SPSed composites increases from 99.21% to 99.65% after HER. Nano-size B4C particles distribute mainly at the gap of 6061Al particles in as-SPSed composites, while the microstructure presents more homogeneous after HER. Pin effect of nano-size B4C particles stimulates dynamic recrystallization (DRX) and grain refining. Texture orientation of the 6061Al grain exists in the as-extruded and as-rolled B4C/6061Al NCs. No new phases are detected in composites in all deformation stages. The tensile strength of as-SPSed composites increases when compared with 6061Al matrix, and the tensile strength of as-rolled composites after hot extrusion is enhanced to 305 MPa. Fracture mechanisms of as-extruded and as-rolled composites mainly include 6061Al matrix tear, particle/matrix interfacial tear and micro-size B4C particle fracture.

What's New in Pediatric Upper Extremity Sports Injuries?

Sports injuries are common in pediatric and adolescent patients and the evaluation and treatment of these injuries continues to evolve. The purpose of this review is to provide a comprehensive appraisal of the most recent literature, highlighting updates on sports-related upper extremity injuries in pediatric patients. An electronic search of the PubMed, EMBASE, and Google Scholar databases was performed for keywords related to pediatric overhead athletes, osteochondritis dissecans (OCD) of the capitellum, medial epicondyle fractures, shoulder instability, and clavicle fractures. Search results were filtered by publication date to yield articles published electronically or in print on or after January 1, 2013 to May 30, 2017. Papers were selected based on expert opinion and consensus by the authors and included if deemed to have contributed important findings to the above topics. A total of 51 articles were deemed to have contributed significant findings to the literature: 11 overhead athlete, 9 OCD of the capitellum, 6 medial epicondyle fractures, 17 shoulder instability, and 8 clavicle fractures. The level of evidence for most studies was either Level III or IV. Overuse and traumatic conditions of the pediatric elbow including UCL tear, capitellar OCD, and medial epicondyle fractures represent a significant portion of injuries in the overhead athlete. Research in the prevention and treatment of primary and recurrent shoulder instability in young athletes continues to evolve. The operative treatment of clavicle fractures in adolescents has been increasing without a commensurate increase in the level of evidence supporting such treatment. Advances have been made in the treatment of sports-related upper extremity injuries in pediatric patients, however, high-level, comparative outcomes research in many areas is lacking and this review may help inform topics for future study. Level IV-Literature review.

Is Treatment of Segond Fracture Necessary With Combined Anterior Cruciate Ligament Reconstruction?

Background: There is a paucity of clinical information to guide the treatment of a combined anterior cruciate ligament (ACL) tear and Segond fracture. Purpose: To compare clinical outcomes, graft failure rates, and activity levels between patients undergoing ACL reconstruction (ACLR) with and without an untreated Segond fracture at a minimum 2-year follow-up. Study Design: Cohort study; Level of evidence, 3. Methods: This study included a group of patients with a combined ACL tear/untreated Segond fracture that was matched based on age, sex, body mass index, and graft type to a control group of patients with an ACL tear and no Segond fracture. All patients were treated with ACLR alone between the years of 2000 and 2015. The diagnosis of a Segond fracture, or bony avulsion of the anterolateral complex, was made by radiographic analysis. Data regarding the initial injury, surgical intervention, and physical examination findings were recorded. Clinical and functional outcomes were obtained using physical examination results, International Knee Documentation Committee (IKDC) subjective scores, and Tegner activity levels. Results: Twenty patients (16 male, 4 female) with a combined ACL tear/untreated Segond fracture with a mean age of 26.3 years (range, 13-44 years) were matched to a control group of 40 patients (32 male, 8 female) with an ACL tear and no Segond fracture with a mean age of 26.4 years (range, 13-47 years). The study group was followed for a mean of 59.1 months (range, 24-180 months) and the control group for a mean of 55.5 months (range, 24-120 months). The mean IKDC score was 86.5 (range, 54-100) for the study group compared with 93.0 (range, 54-100) for the control group (P = .03). The graft rupture rate was 10% for both groups (P = .97). The mean time to rupture was 33.0 months (range, 21-45 months) in the study group and 63.5 months (range, 39-88 months) in the control group (P = .24). Patients in the study group had significantly more anteroposterior instability by preoperative Lachman testing than those in the control group (control group: 0 normal, 3 grade 1+, 37 grade 2+, 0 grade 3+; study group: 0 normal, 1 grade 1+, 10 grade 2+, 9 grade 3+; P = .0001). There was no significant difference between the 2 groups in regard to postoperative Lachman testing (control group: 35 normal, 3 grade 1+, 2 grade 2+, 0 grade 3+; study group: 17 normal, 3 grade 1+, 0 grade 2+, 0 grade 3+; P = .31). Patients in the study group had significantly more instability by preoperative pivot-shift testing than those in the control group (control group: 0 normal, 7 grade 1+, 33 grade 2+, 0 grade 3+; study group: 1 normal, 1 grade 1+, 11 grade 2+, 7 grade 3+; P = .0003). No significant difference was found between the 2 groups for postoperative pivot-shift testing (control group: 36 normal, 2 grade 1+, 2 grade 2+, 0 grade 3+; study group: 18 normal, 1 grade 1+, 1 grade 2+, 0 grade 3+; P = .61) or final Tegner activity level (median, 6). Conclusion: At midterm follow-up, patients undergoing ACLR with and without a Segond fracture had similar pivot-shift test results, graft failure rates, and activity levels. The IKDC score was statistically worse in the patients with a combined ACL tear/untreated Segond fracture, but the difference was less than the minimal clinically important difference for the IKDC score. These findings suggest that patients with a combined ACL tear/untreated Segond fracture can have comparable outcomes to patients with an ACL tear and no Segond fracture when treated with ACLR alone.

“A new physical aspect for elastic-viscous transition and velocity jump in fracture of rubbers”

The elastic-viscous transition of tear fracture of rubber consists of three different fracture zones, the elastic-brittle fracture zone, the viscous-ductile fracture zone and the intermediate transition zone accompanied with stick-slip motion and a corresponding velocity jump at a constant strain energy release rate. Following the previous paper where the fundamental concept named the elastic-viscous transition for the velocity jump was newly introduced, here in addition the authors propose another new physical concept for the mechanism of the elastic-viscous transition in comparison with the phase transition of water. The vibrational energy caused by the stick-slip motion converted from the external strain energy works as a driving force for the velocity jump, being similar to the situation when the latent heat converted from an external heating source causes a volume jump in the phase transition of water.The greatly increased vibrational energy might be consumed to accelerate the ductile fracture of the newly induced fraction of the glassy state in the transition process from the rubbery to glassy state around the glass transition region, resulting in the velocity jump at the elastic-viscous transition. It is the purpose of this paper to answer the essential question why the abrupt and significant velocity change occurs under circumstances where the input strain energy release rate is kept constant.

Liberation properties of middling coking coal under shear force

The relationship between shear force and selective liberation of middling coking coal was investigated by crushing the coal at different shear angles (15°, 30°, 45°, 60°, and 75°). Subsequent analysis of the middling coking coal revealed that as the ash content of coal increased, the shear strength and cohesion increased, while the internal friction angle gradually decreased. Increasing the shear angle caused a gradual increase in the quantity of coarse particles and a decrease in the quantity of fine particles, ultimately leading to a dominant particle size of >10mm at a shear angle of 75°. The cumulative ash and cumulative yield curves showed that the liberation of middling coking coal through crushing was optimum when the shear angle was smaller than the internal friction angle. Lamellar tear fractures observed with low-shear-angle crushing could contribute to the liberation of coal, but the step-like morphology characteristics of medium and high shear angles was not conducive to liberation. Because the liberation of middling coking coal through crushing was optimum when the shear angle was smaller than the internal friction angle, a high ash content or high shear angle may make the release of clean coal more difficult.

Structure and properties of styrene-butadiene rubber (SBR) with pyrolytic and industrial carbon black

To evaluate the performance of pyrolytic carbon black (pCB), we filled styrene-butadiene rubber (SBR) with pCB and N330 industrial carbon black (CB). We used two ratios of pCB and N330: 1/9 and 1/1. N330 was selected because its specific surface area was close to that of pCB. The overall CB content in the mixes was 0, 30, 45 and 60 part per hundred rubber (phr). We studied the effects of types and amounts of CB on the dispersion, cure behavior, dynamic mechanical thermal behavior, tensile mechanical and fracture mechanical properties of the filled rubbers. Dispersion of pCB was poorer than that of N330 CB. With respect to tensile mechanical properties – except tear strength – N330 outperformed pCB. The tear strength and fracture mechanics characteristics (J-integral at crack tip opening, and trouser tear strength) of SBR were higher with pCB than with N330. This can be attributed to the broader dispersion of pCB than N330. The combined use of N330 and pCB resulted in intermediate values, reflecting the actual N330/pCB ratio for all measured parameters. We wanted to correlate the mechanical performance with the apparent molecular weight between crosslinks (Mc), and found reasonable correlations for the Payne effect, tensile strength and critical J-integral. On the other hand, we only found a tendency for tear characteristics; this was ascribed to additional effects of (p)CB dispersion.

Effect of modified flux on MIG arc brazing-fusion welding of aluminum alloy to steel butt joint

Pulsed MIG arc brazing-fusion welding process was applied to realize the butt joining of galvanized steel and 5052 aluminum alloy with no enclosed slot or groove adopted. A modified flux mixture was developed to improve the butt joint performance. After applying the modified flux, weld appearance became better and the spreadability of filler metal was also greatly improved. During brazing-fusion welding process, flux floating on the surface of welding pool weakened the surface tension between filler metal and Fe and reduced the evaporation of Zn, which both led to the greatly enhanced spreadability. The analysis of intermetallic compounds (IMCs) at brazed interface showed that Fe3Al was formed at upper side of steel plate, while Fe2Al5 was formed at other areas with the consideration of its lowest Gibbs free energy under certain temperature range. With modified flux, the tensile strength of the joint could reach up to 120MPa, which was about 60% of that of 5052 aluminum alloy base metal. From the fractured surface, two different fracture modes were identified, tear fracture and intergranular fracture, which confirmed that joint fractured in a brittle mode. The crack initiated at the front side of brazed interface due to the thicker IMCs layer, then propagated to the surface before the whole joint failed. The improved spreadability of filler metal on the top and back sides of steel plate due to the application of flux, contributed to the improvement of joint strength.

Correlation of parameters on preoperative CT images with intra-articular soft-tissue injuries in acute tibial plateau fractures: A review of 132 patients receiving ARIF

IntroductionTibial plateau fractures often occur in conjunction with soft-tissue injuries of knees. The hypothesis of this study is that parameters of CT imaging can predict intra-articular soft-tissue injuries. Patients and methodsPatients who underwent arthroscopically assisted reduction and internal fixation (ARIF) for acute tibial plateau fractures performed by a single orthopedic surgeon between 2005 and 2015 were included in this retrospective study. Patients with concomitant ipsilateral femoral fractures, who had received revision surgery or who had undergone index surgery more than 30days from the event were excluded. We measured lateral plateau depression and widening, medial plateau depression and displacement, and column involvement observed on preoperative CT scans. Intra-articular soft-tissue injuries were diagnosed based on findings from knee arthroscopy. The correlation of imaging parameters with soft-tissue injuries was analyzed by the area under a receiver operating characteristic (AUROC) curve and multivariate logistic regression. ResultsOne-hundred and thirty-two patients were enrolled in the study. The average age was 45.7±13.1 years (range: 18–75 years). Lateral tibial plateau depressions >11mm were significantly associated with increased risk of lateral meniscus tears (p=0.001). However, there was no significant threshold of lateral tibial plateau widening that could be used to predict lateral meniscus tear. Greater risk of anterior cruciate ligament (ACL) avulsion fracture was observed in younger patients, patients with high-energy-pattern tibial plateau fractures, patients with fractures involving anteromedial or posterolateral columns, and patients with medial tibial plateau displacement >3mm (p<0.05). ConclusionMeasuring lateral tibial plateau depression and column involvement on preoperative CT scans can help predict a higher risk of lateral meniscus tear and ACL avulsion fracture respectively in patients with acute tibial plateau fractures.

Fracture as a wear mechanism of ceramics based on a partially stabilized zirconia during dry friction against steel

The results of wear of four ceramic materials made of a partially stabilized zirconia (Y-TZP, YPCZ, Ce-TZP and Mg-PSZ) during friction against steel without lubrication are presented. It is shown that wear of ceramics from Y-TZP, Y-PSZ, and Ce-TZP occurs in two stages: first it’s a tear fracture and then it’s a shear fracture. The ceramics based on Mg-PSZ wears out by only the mechanism of shear fracture. Proceeding from the analysis, it was concluded that the wear mechanism of the ceramics under study depends on the grain boundary strength.