Lateral femoral neck stress fractures: A case report

BACKGROUND Sport-induced injuries particularly affect young,healthy,and active individuals.Running,a popular and accessible sport,can cause a wide range of injuries,including stress fractures.Stress fractures can occur during high-intensity training or competitions,especially among well-trained amateurs and professional athletes.Adequate diagnosis can be complicated by the typically young age,unremarkable medical history,and vital condition of the patient.Stress fractures present insidiously,and this is specifically the case with stress fractures of the femoral neck.Timely intervention is crucial to prevent progressive displacement,as this can damage the blood supply to the femoral head.CASE SUMMARY A 30-year-old male runner presented to our outpatient clinic with persistent pain 3 weeks after running a marathon.X-ray showed a complete lateral fracture of the left femoral neck,which was treated surgically with a dynamic hip screw.CONCLUSION It is essential for healthcare providers to be vigilant for the subtle symptoms of stress fractures to ensure timely treatment.Early recognition prevents com-plication and leads to a better prognosis.

Stress fractures in uncommon location:Six case reports and review of the literature

BACKGROUND Individuals’interest in sports activities has been increasing,contributing to more stress fracture occurrences in uncommon locations on the skeleton.In this study,several cases of stress fractures in atypical locations are presented,and the possibility of combining diagnostic methods to make accurate and quick diagnoses is explored.Additionally,different causes of stress fractures,as well as various modalities of treatment,are highlighted.Other potential factors of stress fractures were identified by a literature review.CASE SUMMARY Six cases of stress fractures in the calcaneus,intermediate cuneiform bone,sacrum,tibia(bilateral),navicular bone and femoral neck are presented,with different types of diagnostic imaging and treatments.All of the cases were associated with an aspect of mobility because all of the patients were physically active in various sport disciplines.CONCLUSION The type of therapeutic procedure selected should depend on the specific clinical case,i.e.,the patient’s condition and level of physical activity.

Multiple stress fractures of unilateral femur:A case report

BACKGROUND Stress fractures of the femoral neck are not common in clinical practice,and simultaneous stress fractures of the femoral neck and proximal femur of the unilateral femur are even more rare.We introduce a case of this type of fracture that was treated in our department,analyze the causes,and review similar stress fractures reported in the literature to provide references for the diagnosis and treatment of such conditions.CASE SUMMARY A 62-year-old female,with a free medical history,was admitted to the hospital mainly due to pain in the right hip and worsening pain in the right thigh.The patient had no obvious history of trauma.X-ray and computed tomography showed fracture of the femoral neck and proximal femur.The patient had undergone surgery 1 year prior to address a fracture of the left proximal femur that had occurred in a traffic accident.Our first consideration was stress fracture of the femoral neck;however,simultaneous stress fractures of the femoral neck and proximal femur of the unilateral femur were seen.The femoral neck stress fracture was a tension fracture,with obvious displacement and varus deformity of the hip.Considering that the patient was an elderly female,we performed total hip arthroplasty.Follow-up X-rays showed that the stress fracture of the proximal femur had mostly healed after 3 mo.CONCLUSION Muscle fatigue and hip varus deformity provide an anatomical basis for the occurrence of femoral neck stress fractures.

Femoral neck stress fractures after trampoline exercise:A case report

BACKGROUND Femoral neck stress fractures(FNSFs)are commonly found in long-distance running athletes.For FNSFs,early diagnosis and proper treatment are important.The objective of this study was to report FNSFs that occurred after excessive exercise using trampoline in middle-aged women.CASE SUMMARY The patient was a 43-year-old woman who exercised jumping on a trampoline for 6 wk for 1-3 h a day to diet.Exercise includes repeated flexion-extension of the hip joint.The patient was admitted to the hospital due to sudden bilateral groin pain that occurred suddenly during a trampoline exercise.Hip magnetic resonance imaging(MRI)revealed bilateral FNSFs.After 2 wk of follow-up with conservative treatment,the pain slightly decreased.However,it did not disappear completely.It was determined that it was difficult to control symptoms only by conservation treatment.Thus,closed reduction and internal fixation using a cannulated screw were performed for the more painful left hip joint.After operation,the pain was improved.Walking using crutches was possible.Followup MRI showed that the right femoral head signal was decreased compared to the left femoral head signal.Therefore,nonsteroidal anti-inflammatory drug and conservative treatment were provided.CONCLUSION In middle-aged people,excessive trampoline exercise can repeat hip flexion and extension for a short period of time,leading to FNSFs.

Total knee arthroplasty with long tibial stem for tibial stress fractures with knee osteoarthritis:Two birds with one stone

Purpose:The treatment and outcome of tibial stress fractures concomitant with knee osteoarthritis(OA)are complicated.The aim of this study was to evaluate the functional and radiological outcome of total knee arthroplasty with long tibial stem as a treatment for patients having knee OA and tibial stress fracture.Methods:Patients who were diagnosed to have proximal tibia stress fracture along with knee OA at our institution between June 2013 and November 2018 were included in our study.All patients underwent total knee arthroplasty with long tibial stem.Preoperative and postoperative functional assessments were done according to range of movement of the knee joint,knee society score and knee injury and OA outcome score.Descriptive analysis was carried out by mean and standard deviation for quantitative variables,frequency and proportion for categorical variables.Results:Twelve patients were included in the study.All patients were found to have stress fractures in the proximal half of tibia and extra-arthrosis.Four patients had non-union/delayed union,and 8 patients had acute fractures.The average preoperative range of movement was 88.1°,which improved to 116.3°at 3 months following surgery.It was found that the fracture has healed in all cases.Mean knee society score improved from 32.9 preoperatively to 89.3 at 1 year follow-up.Knee injury and OA outcome score improved from a mean score of 28.3 preoperatively to 81.1 at 1 year follow-up.Conclusion:Stress fractures can occur in the proximal tibia in patients with knee OA.Total knee arthroplasty with tibial stem provides a suitable solution for both conditions.Additional plating or bone graft is unlikely to be required.

Bilateral stress fractures of femoral neck in non-athletes： a report of four cases

Femoral neck stress fractures （FNSFs） are rare, constituting only 5% of all stress fractures in young adults. These fractures are usually seen in athletes, military recruits and patients with underlying metabolic diseases. The treatment of FNSFs is still controversial because of the inherent complications associated with the treatment procedure. We came across 4 cases of bilateral FNSFs in non-athletic individuals who were manual labourers with- out underlying bony disorders. Two patients with FNSFs and coxa vara deformity on both sides were managed by subtrochanteric valgus osteotomy and dynamic hip screw fixation. One of the remaining two patients was treated by cannulated cancellous screw fixation on one side and sub- trochanteric valgus osteotomy on the other side. The fourth patient received subtrochanteric valgus osteotomy on oneside and bipolar hemiarthroplasty on the other side after failed cannulated screw fixation. All the fractures healed without any complications. No evidence of avascular ne- crosis or arthritis was noted in our series. Subtrochanteric valgus osteotomy restores normal neck-shaft angle in pa- tients suffering from FNSFs combined with coxa vara deformity. Moreover, it helps to bring the forces acting around the hip to normal biomechanical levels, leading to fracture union and better results. Replacement arthroplasty is recommended to patients who fail to achieve bony union after fixation.

Impact loading in female runners with single and multiple bone stress injuries during fresh and exerted conditions

Background:Bone stress injuries(BSIs)are common in female runners,and recurrent BSI rates are high.Previous work suggests an association between higher impact loading during running and tibial BSI.However,it is unknown whether impact loading and fatigue-related loading changes discriminate women with a history of multiple BSIs.This study compared impact variables at the beginning of a treadmill run to exertion andthe changes in those variables with exertion among female runners with no history of BSI as well as among those with a history of single or multiple BSIs.Methods:We enrolled 45 female runners(aged 18-40 years)for this cross-sectional study:having no history of diagnosed lower extremity BSI(N-BSI,n=14);a history of 1 lower extremity BSI(1-BSI,n=16);and diagnosed by imaging,or a history of multiple(>3)lower extremity BSIs(M-BSI,n=15).Participants completed a 5-km race speed run on an instrumented treadmill while wearing an Inertial Measurement Unit.The vertical average loading rate(VALR),vertical instantaneous loading rate(VILR),vertical stiffness during impact via instrumented treadmill,and tibial shock determined as the peak po sitive tibial acceleration via Inertial Measurement Unit were measured at the beginning and the end of the run.Results:There were no differences between groups in VALR,VILR,vertical stiffness,or tibial shock in a fresh or exerted condition.However,compared to N-BSI,women with M-BSI had greater increase with exertion in VALR(-1.8%vs.6.1%,p=0.01)and VILR(1.5%vs.4.8%,p=0.03).Similarly,compared to N-BSI,vertical stiffness increased more with exertion among women with M-BSI(-0.9%vs.7.3%,p=0.006)and 1-BSI(-0.9%vs.1.8%,p=0.05).Finally,compared to N-BSI,the increase in tibial shock from fresh to exerted condition was greater among women with M-BSI(0.9%vs.5.5%,p=0.03)and 1-BSI(0.9%vs.11.2%,p=0.02).Conclusion:Women with 1-BSI or M-BSIs experience greater exertion-related increases in impact loading than women with N-BSI.These observations imply that exertion-related changes in gait biomechanics may contribute to risk of BSI.

In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning

A coal mine in New South Wales is longwall mining 300 m wide panels at a depth of 160–180 m directly below a 16–20 m thick conglomerate strata. As part of a strategy to use hydraulic fracturing to manage potential windblast and periodic caving hazards associated with these conglomerate strata,the in-situ stresses in the conglomerate were measured using ANZI strain cells and the overcoring method of stress relief. Changes in stress associated with abutment loading and placement of hydraulic fractures were also measured using ANZI strain cells installed from the surface and from underground. Overcore stress measurements have indicated that the vertical stress is the lowest principal stress so that hydraulic fractures placed ahead of mining form horizontally and so provide effective pre-conditioning to promote caving of the conglomerate strata. Monitoring of stress changes in the overburden strata during longwall retreat was undertaken at two different locations at the mine. The monitoring indicated stress changes were evident 150 m ahead of the longwall face and abutment loading reached a maximum increase of about7.5 MPa. The stresses ahead of mining change gradually with distance to the approaching longwall and in a direction consistent with the horizontal in-situ stresses. There was no evidence in the stress change monitoring results to indicate significant cyclical forward abutment loading ahead of the face. The forward abutment load determined from the stress change monitoring is consistent with the weight of overburden strata overhanging the goaf indicated by subsidence monitoring.

Femoral neck stress fracture and medial tibial stress syndrome following high intensity interval training: A case report and review of literature

BACKGROUND Femoral and tibial stress injuries are commonly found in long distance running athletes.Stress fractures have rarely been reported in athletes performing high intensity interval training(HIIT)exercise.The objective of this study was to report a case of a patient who presented with medial tibial stress syndrome and femoral neck stress fracture after performing HIIT exercises.CASE SUMMARY A 26 year old female presented with bilateral medial tibial pain.She had been performing HIIT exercise for 45 min,five times weekly,for a seven month period.Her tibial pain was gradual in onset,and was now severe and worse on exercise,despite six weeks of rest.Magnetic resonance imaging(MRI)revealed bilateral medial tibial stress syndrome.As she was taking norethisterone for birth control,a dual energy X-ray absorbitometry scan was performed which demonstrated normal bone mineral density of her lumbar spine and femoral neck.She was managed conservatively with analgesia and physiotherapy,but continued to exercise against medical advice.She presented again six months later with severe right hip pain.MRI of her right hip demonstrated an incomplete stress fracture of her subtrochanteric region.Her symptoms resolved with strict rest and physiotherapy.CONCLUSION HIIT may cause stress injury of the tibia and femur in young individuals.

Study on in-situ stress measurement around coastal marginal land in Fujian

The in-situ hydraulic fracturing stress measurements have been carried out around the coastal marginal land in Fu- jian Province. And the characteristics of magnitude, direction and distribution of tectonic stress have been obtained. Based on the observed stress data, the characteristics and activities of fault zones are analyzed and studied in the paper according to the Coulomb friction criteria. 1 The maximum horizontal principal compressive stress is in the NW-WNW direction from the north to the south along the coastline verge, which is parallel to the strike of the NW-trending fault zone, consistent with the direction of principal compressive stress obtained from geological structure and across-fault deformation data, and different from that reflected by focal mechanism solution by about 20°. 2 The horizontal principal stress increases with depth, the relation among three stresses is SH>Sv>Sh or SH≈Sv>Sh, and the stress state is liable to normal fault and strike-slip fault activities. 3 According to Coulomb friction criteria and taking the friction strength μ as 0.6~1.0 for analysis, the stress state reaching or exceeding the threshold for normal-fault frictional sliding near the fault implies that the current tectonic activity in the measuring area is mainly normal faulting. 4 The force source of current tectonic stress field comes mainly from the westward and northwestward horizontal extrusions from the Pacific and Philippine Plates respectively to the Eurasian Plate.

Effects of Strain Rate on Stress Corrosion of S355 Steel in 3.5% NaCl Solutions

The stress corrosion of S355 steel in 3.5% NaCl solution under the different strain rates was analyzed with the slow strain rate test（SSRT）, the stress corrosion cracking（SCC） behaviors of S355 steel under the different strain rates in the solution were investigated, and the fracture morphologies and compositions of corrosion products under the different strain rates were analyzed with scanning electron microscopy（SEM） and energy dispersive spectrometerry（EDS）, respectively. The experimental results show that the SCC sensitivity index is the highest when the strain rate is 2×10-6, and the medium corrosion is the main reason resulting in the highest SCC sensitivity index. The SCC sensitivity index is the least when the strain rate is 5×10-6, and the stress is the main reason resulting in the stress corrosion. The SCC sensitivity index is the middle when the strain rate is 9×10-6, the interaction of stress and medium is the stress corrosion fracture mechanism.

Management of proximal tibial stress fracture associated with advanced knee osteoarthritis:A systematic review

Purpose:Tibial stress fracture associated with knee osteoarthritis is an unusual and difficult clinical scenario.There is no clear existing treatment guideline for this uncommon clinical disease.The aim of this study is to review the impact of various treatment options for patients with advanced knee osteoarthritis associated with proximal tibial stress fracture.Methods:The study was performed using the databases of PubMed and Scopus.Methodological index for non-randomized studies score was used to evaluate the included studies’bias.The concluded data included the treatment approach,reported outcome measure,and time to fracture union.The literature search was started in December 2021 and accomplished in January 2022.A narrative description of the different methods and comparison of their results were done.Results:Out of total assessed 69 studies,9 studies were included in our review.The commonest treatment approach used was total knee arthroplasty by long tibial stem extension.The mean preoperative knee society score and knee functional score were 30.62 and 23.17,respectively.The mean postoperative knee society knee score was 86.87,while the functional score was 83.52.The average reported time to achieve fracture union was 4 months(a range of 2.07-5.50 months).Conclusion:The optimal clinical outcome for treating either acute or mobile tibial stress fracture in patients with advanced knee osteoarthritis can be achieved with long stem total knee arthroplasty.However,due to heterogeneity of data,comparison of different treatment options for chronic proximal tibial stress fracture mal-union/non-union coexisting with knee osteoarthritic and such inferences need to be judged cautiously.

SIF-based fracture criterion for interface cracks

The complex stress intensity factor K governing the stress field of an interface crack tip may be split into two parts, i.e.,■ and s^（-iε）, so that K = ■ s^（-iε）, s is a characteristic length and ε is the oscillatory index. ■ has the same dimension as the classical stress intensity factor and characterizes the interface crack tip field. That means a criterion for interface cracks may be formulated directly with■, as Irwin（ASME J. Appl. Mech. 24：361–364, 1957） did in 1957 for the classical fracture mechanics. Then, for an interface crack,it is demonstrated that the quasi Mode I and Mode II tip fields can be defined and distinguished from the coupled mode tip fields. Built upon SIF-based fracture criteria for quasi Mode I and Mode II, the stress intensity factor（SIF）-based fracture criterion for mixed mode interface cracks is proposed and validated against existing experimental results.

Crimp feasibility of AZ31 magnesium alloy wide plate at warm temperatures responding to asymmetry

The crimp feasibility of AZ31 Mg alloy wide plate responding to asymmetry and anisotropy at different temperatures was conducted by bending experiments and numerical simulation.Through the microstructural characteristic,mechanical properties,EBSD and FEM analysis,the results indicated that{10-12}twins and pyramidal(a)slip were dominated at the inner surface layer of the plate,while prismatic and pyramidal(a)slips were controlled at the outer layer when bending at 100℃,and their quantity decreased as the temperature elevation and vanished at 200℃.The flexural deflection increased gradually with the augment of flexural temperature,while the fracture stress weakened.A large number of twins nucleated and grew in the coarse grain,causing major distribution proportion of high angular grain boundaries(HAGBs)at the compression part,which could improve its flexural properties and affect subsequent strain contours,twins and recrystallization distribution.The offset of the neutral layer declined from 1.4125 mm to 0.7261 mm with the temperature rising from 100℃to 250℃when bending,while it was concentrated on 0.0338-0.0481 mm when coiling,accounting for 0.26%-0.37%of the plate thickness.At last,the reel diameter descended with increasing the temperature and coiling rate.

Impact Toughness Scattering of Bainitic Steel in the Ductile-brittle Transition Temperature Region

The impact toughness scattering in the ductile-brittle transition temperature （DBTT） region was experimentally examined on mixed and homogeneous grains of low alloy high strength bainitic steel under dynamic loading conditions. The results revealed that the mixed grain microstructure had larger impact toughness scattering than the homogeneous one, and the impact toughness scattering was mainly caused by the scattering in the cleavage fractttre stress σf. The value of σf. is related to the size of the microcrack formed in the bainitic packet. When a bainitic packet-sized microcrack propagates from one bainitic packet into the adjacent packet, cleavage fracture occurs. The cleavage fracture is controlled by the few coarse packets in the microstructures, and the σf scattering is influenced by the varied distances/relative locations between these coarse packets, and homogenizing the distribution of fine bainitic packet sizes is an effective way to reduce the impact toughness scattering in the DBTT region.

Fabrication and Thermal Structural Characteristics of Ultra-high Temperature Ceramic Struts in Scramjets

ZrB_2-SiC based ultra-high temperature ceramic（UHTC） struts were firstly proposed and fabricated with the potential application in the combustor of scramjets for fuel injection and flame-holding for their machinability and excellent oxidation/ablation resistance in the extreme harsh environment. The struts were machined with electrospark wire-electrode cutting techniques to form UHTC into the desired shape, and with laser drilling to drill tiny holes providing the channels for fuel injection. The integrated thermal-structural characteristic of the struts was evaluated in high-temperature combustion environment by the propane-oxygen free jet facility, subject to the heat flux of 1.5 MW/m^2 lasting for 300 seconds, and the struts maintained integrity during and after the first experiment. The experiments were repeated for verifying the reusability of the struts. Fracture occurred during the second repeated experiment with the crack propagating through the hole. Finite element analysis（FEA） was carried out to study the thermal stress distribution in the UHTC strut. The simulation results show a high thermal stress concentration occurs at the hole which is the crack initiation position. The phenomenon is in good agreement with the experimental results. The study shows that the thermal stress concentration is a practical key issue in the applications of the reusable UHTC strut for fuel injection structure in scramjets.

Dynamic Crack Propagation Analysis Using Scaled Boundary Finite Element Method

The prediction of dynamic crack propagation in brittle materials is still an important issue in many engineering fields. The remeshing technique based on scaled boundary finite element method(SBFEM) is extended to predict the dynamic crack propagation in brittle materials. The structure is firstly divided into a number of superelements, only the boundaries of which need to be discretized with line elements. In the SBFEM formulation, the stiffness and mass matrices of the super-elements can be coupled seamlessly with standard finite elements, thus the advantages of versatility and flexibility of the FEM are well maintained. The transient response of the structure can be calculated directly in the time domain using a standard time-integration scheme. Then the dynamic stress intensity factor(DSIF) during crack propagation can be solved analytically due to the semi-analytical nature of SBFEM. Only the fine mesh discretization for the crack-tip super-element is needed to ensure the required accuracy for the determination of stress intensity factor(SIF). According to the predicted crack-tip position, a simple remeshing algorithm with the minimum mesh changes is suggested to simulate the dynamic crack propagation. Numerical examples indicate that the proposed method can be effectively used to deal with the dynamic crack propagation in a finite sized rectangular plate including a central crack. Comparison is made with the results available in the literature, which shows good agreement between each other.

On the physical model of earthquake precursor fields and the mechanism of precursors＇timespace distribution──origin and evidences of the strong body earthquake──generating model

According to the requirement of the project 'Establishment of the Physical Model of Earthquake PrecursorFields',this paper elucidates the train of thinking for research on the project and some scientific problems whichmust be studied i, the elucidation emphasizes that the core of this project is to study the conditions and processesof the generation of strong earthquakes. The paper first outlines the origin and development of the'strong-bodyearthquake-generating model' proposed by the author in the 1980;and then proves the reasonableness of themodel from three aspects, namely: deep structures, mechanical analysis and rock fracture experiments. Bystudying the tomographic image for the northern part of North China, it can be seen that the sources of strongearthquakes are all distributed in high-velocity bodies,or in the contact zone between high-velocity and lowvelocity bodies but nearer to the high-velocity body. It has been affirmed through studies of the mechanical modelsof hard and soft inclusions that the existence of a hard inclusion is an imPOrtant condition for the high concentration of large amounts of strain energy. A lot of theoretical and experimental studies have been made to investigate the conditions for rock instability; the results have consistently indicated that rock instability,sudden fracture and stress drop would be possible only if the stiffness of the source body is greater than the environmentalstiffness.

Effects and mechanism of platelet-rich plasma on military drill injury: A review

Military drill injury is a significant part of military medical research.The increase of training intensity and changes in training methods lead to differences in injury types.The ideal therapeutic modality should allow rapid healing at a reasonable cost and minimize impact on patients’life.Platelet-rich plasma(PRP),a platelet concentrate,is rich in a variety of growth factors and widely used clinically as a minimally invasive treatment.It plays an important role in injury repair and rehabilitation.In this article,we review the therapeutic role of PRP in military drill injury and its possible underlying mechanisms,with a focus on plantar fasciitis,stress fractures and other common injuries,in order to provide basic support for military reserve.

Study of experiment method for triaxial frost heaving constitutive relation of frozen soil

A new experiment method is introduced to study the relations between frost heaving strain and stress of soil or fracture rock under different moisture contents, temperatures and stress states. Based on experiments, a new triaxial frost heaving stress-strain relation is presented aiming at tunnel in cold regions. The experimental equipments are strain-controlled and low temperature buildup, and different restrained conditions are controlled by changing the stiffness of a test-force-ring. Then the frost heaving strain and stress of soil or fracture rock can be obtained under different restrained conditions, and the frost heaving stress-strain relation can be got by regression analysis of some feature points. Experiments of saturated sandy soil conducted by this method show that the triaxial frost heaving stress-strain relation could be expressed by logarithmic curves, and the frost heaving stress changes linearly with the logarithm of the frost heaving strain. The stronger the constraint, the smaller the frost heaving strain and the larger the frost heaving stresses. The frost heaving stresses would tend to a limit value with increasing the constraint intensity. The larger the confining pressure, the larger the frost heaving strain and stress.