Stress tensor determination by modified hydraulic tests on pre-existing fractures:Method and stress constraints

The hydraulic testing of pre-existing fractures(HTPF)is one of the most promising in situ stress measurement methods,particularly for three-dimensional stress tensor determination.However,the stress tensor determination based on the HTPF method requires at least six tests or a minimum of 14-15 tests(under different conditions)for reliable results.In this study,we modified the HTPF method by considering the shear stress on each pre-existing fracture,which increased the number of equations for the stress tensor determination and decreased the number of tests required.Different shear stresses were attributed to different fractures by random sampling;therefore,the stress tensors were obtained by searching for the optimal solution using the least squares criterion based on the Monte Carlo method.Thereafter,we constrained the stress tensor based on the tensile strength criterion,compressive strength criterion,and vertical stress constraints.The inverted stress tensors were presented and analyzed based on the tensorial nature of the stress using the Euclidean mean stress tensor.Two stress-measurement campaigns in Weifang(Shandong Province,China)and Mercantour road tunnel(France)were implemented to highlight the validity and efficiency of the modified HTPF(M-HTPF)method.The results showed that the M-HTPF method can be applied for stress tensor inversion using only three to four tests on pre-existing fractures,neglecting the stress gradient.The inversion results were confined to relatively small distribution dispersions and were significantly reliable and stable due to the shear stresses on the fractures and the stress constraints employed.The M-HTPF method is highly feasible and efficient for complete stress tensor determination in a single borehole.

Correlation between anxiety, depression, and social stress in young patients with thoracolumbar spine fractures

BACKGROUND Traumatic injuries,such as falling,car accidents,and crushing mostly cause spinal fractures in young and middle-aged people,and>50%of them are thoracolumbar fractures.This kind of fracture is easily combined with serious injuries to peripheral nerves and soft tissues,which causes paralysis of the lower limbs if there is no timely rehabilitation treatment.Young patients with thoracolumbar fractures find it difficult to recover after the operation,and they are prone to depression,low self-esteem,and other negative emotions.AIM To investigate the association between anxiety,depression,and social stress in young patients with thoracolumbar spine fractures and the effect on rehabilitation outcomes.METHODS This study retrospectively analyzed 100 patients admitted to the orthopedic department of Honghui Hospital,Xi’an Jiaotong University who underwent thoracolumbar spine fracture surgery from January 2022 to June 2023.The general data of the patients were assessed with the Hamilton anxiety scale(HAMA),Hamilton depression scale(HAMD),life events scale,and social support rating scale(SSRS)to identify the correlation between anxiety,depression scores,and social stress and social support.The Japanese Orthopedic Association(JOA)was utilized to evaluate the rehabilitation outcomes of the patients and to analyze the effects of anxiety and depression scores on rehabilitation.RESULTS According to the scores of HAMD and HAMA in all patients,the prevalence of depression in patients was 39%(39/100),and the prevalence of anxiety was 49%(49/100).Patients were categorized into non-depression(n=61)and depression(n=39),non-anxiety(n=51),and anxiety(n=49)groups.Statistically significant differences in gender,occupation,Pittsburgh Sleep Quality Index(PSQI)score,and monthly family income were observed between the non-depression and depression groups(P<0.05).A significant difference in occupation and PSQI score was found between the non-anxiety and anxiety groups.Both depression(r=0.207,P=0.038)and anxiety scores(r=0.473,P<0.001)were significantly and positively correlated with negative life events.The difference in negative life event scores as well as SSRS total and item scores was statist-ically significant between patients in the non-depression and depression groups(P<0.05).The difference between the non-anxiety and anxiety groups was statistically significant(P<0.05)in the negative life event scores as well as the total SSRS scores.Additionally,JOA scores were significantly lower in both anxious and depressed patients.CONCLUSION Young patients with thoracolumbar fractures are prone to anxiety and depression.Patients’anxiety and depression are closely associated with social pressure,which reduces the life pressure of young patients with thoracolumbar fractures,enhances social support,and improves the psychology of anxiety and depression.,which affects patients’recovery.

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.

A new apparatus for investigating stress,deformation and seepage coupling properties of rock fractures

A true triaxial apparatus which is composed of three units was presented.The apparatus allows for investigations on deformation and seepage behaviors of a single rock fracture subjected to lateral stress and normal stress.The first unit has three jacks which can apply loads independently in three orthogonal directions.The second unit is used to supply water inflow,control seepage pressure and measure flow velocity in real time.The third unit is for measuring the normal deformation of rock fractures.Some tests for investigating the normal deformation and seepage behaviors of rock fractures subjected to normal and lateral loads on hard granite specimens with an artificial persistent fracture,were introduced.The results show that both the normal deformation and the hydraulic conductivity are influenced not only by the normal stress but also by the lateral stress.It is also shown that the aperture and the hydraulic conductivity decrease with the increasing normal stress but increase with the increasing lateral stress and both the aperture and the hydraulic conductivity obey exponential relationships with the normal stress and the lateral stress.

Interaction among fractures and stress field computation of fracture systems

The interaction problem among fractures under the action of compressional stress is studied in this paper by using the finite element method and boundary element method respectively.The mechanical criteria which differentiate between the independent fractures and fracture systems and their computation methods are presented in this paper.The proportional conditions between length and spacing of fractures that exist interaction for several kinds of fracture groups of different geometric arrangement are given.The effect of interaction among fractures on the displacement field,stress field and strain energy distribution are computed.The relations between the fracture system of conjugate array and conjugate earthquakes are also discussed in this paper.

Lower limb stress fractures in sport:Optimising their management and outcome

Stress fractures in sport are becoming increasing more common,comprising up to 10%of all of sporting injuries.Around 90%of such injuries are located in the lower limb.This articles aims to define the optimal management of lower limb stress fractures in the athlete,with a view to maximise return rates and minimise return times to sport.Treatment planning of this condition is specific to the location of the injury.However,there remains a clear division of stress fractures by"high"and"low"risk."Low risk"stress fractures are those with a low probability of fracture propagation,delayed union,or non-union,and so can be managed reliably with rest and exercise limitation.These include stress fractures of the PosteroMedial Tibial Diaphysis,Metatarsal Shafts,Distal Fibula,Medial Femoral Neck,Femoral Shaft and Calcaneus."High risk"stress fractures,in contrast,have increased rates of fracture propagation,displacement,delayed and non-union,and so require immediate cessation of activity,with orthopaedic referral,to assess the need for surgical intervention.These include stress fractures of the Anterior Tibial Diaphysis,Fifth Metatarsal Base,Medial Malleolus,Lateral Femoral Neck,Tarsal Navicular and Great Toe Sesamoids.In order to establish the optimal methods for managing these injuries,we present and review the current evidence which guides the treatment of stress fractures in athletes.From this,we note an increased role for surgical management of certain high risk stress fractures to improve return times and rates to sport.Following this,key recommendations are provided for the management of the common stress fracture types seen in the athlete.Five case reports are also presented to illustrate the application of sportfocussed lower limb stress fracture treatment in the clinical setting.

Bilateral sequential femoral neck stress fractures in young adult with HIV infection on antiretroviral therapy: A case report

BACKGROUND Femoral neck stress fractures are rarely encountered among young adults and are often associated with either repetitive excessive loading or underlying bone pathology.Preliminary research has indicated human immunodeficiency virus(HIV)/antiretroviral therapy(ART)as predisposing agents to osteopenia and osteoporosis related complications.We report a case of HIV/ART induced insufficiency fracture in a resource limited setting in Central India.Our aim is to increase awareness and promote screening of HIV/ART related osteopenia and osteoporosis in order to prevent catastrophic orthopaedic complications.CASE SUMMARY A 35-year-old HIV positive male presented with a stress fracture of left femoral neck.The patient was on ART and reported no comorbidities.He went on to be successfully managed surgically.However,during work-up osteopenia of the contralateral proximal femur was recognised using Singh’s Index.Six months post-op the patient presented with right-sided femoral-neck stress fracture.At this stage the patient was nonconcordant with ART and denied surgical fixation.CONCLUSION In the absence of co-morbidities,several mechanisms of HIV/antiretroviral therapy may have played a role in predisposing our patient towards such a presentation.We recommend routine screening all HIV-infected patients for osteopenia,especially in younger individuals.In low resource settings and district hospitals,pelvis radiograph&Singh’s index can be used for screening.

A case－control study on risk factors of stress fractures in military recruits during basic training

Stress fracture(SF) is an important training injury with a high incidence during recruits' basic training. In order to primarily investigate its risk factors and to provide etiologic threads for a further study,we carried out a case control study on SF. The results of univariate analysis and multivariate logistic regression analysis revealed that attending training on the occasion of injury or fatigue , and a lower length ratio of tibia and pelvic limb were the main risk factors of SF. The authors are of the opinion that compared with the absolute length of tibia , the relative length of tibia(tibia length/pelvic limb length) may be more relevant to the tibia biomechanical characteristics. , The harm of attending training under the circumstances of injury or fatigue is discussed in this paper.

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.

Assessment of stress degree and bone metabolism activity in patients with middle humeral shaft fractures after minimally invasive surgery MIPO and open surgery ORIF

Objective:To study the effects of MIPO and ORIF on stress degree and bone metabolism activity in patients with middle humeral shaft fractures.Methods: Patients with middle humeral shaft fractures who received surgical treatment in Mianyang Orthopedic Hospital between June 2010 and October 2015 were enrolled and randomly divided into MIPO group and ORIF group who were treated with minimally invasive plate oateosynthesis and open reduction internal fixation respectively. Before surgery as well as 1 d and 3 d after surgery, serum was collected to determine the contents of stress response molecules and bone metabolism markers.Results:1 d and 3 d after surgery, serum stress molecules PGE2, CRP, NE and E as well as bone resorption markers TRACP-5B,β-CTX, RANK and RANKL contents of both groups were higher than those before surgery while bone formation markers BGP, BALP, PINP and OPG contents were lower than those before surgery;serum stress molecules PGE2, CRP, NE and E as well as bone resorption markers TRACP-5B,β-CTX, RANK and RANKL contents of MIPO group were lower than those of ORFI group while bone formation markers BGP, BALP, PINP and OPG contents were higher than those of ORFI group.Conclusion: Compared with ORIF, MIPO for middle humeral shaft fractures can reduce stress response degree and improve bone metabolism.

Simulation of Paleotectonic Stress Fields and Distribution Prediction of Tectonic Fractures at the Hudi Coal Mine, Qinshui Basin

Study on tectonic fractures based on the inversion of tectonic stress fields is an effective method. In this study, a geological model was set up based on geological data from the Hudi Coal Mine, Qinshui Basin, a mechanical model was established under the condition of rock mechanics and geostress, and the finite element method was used to simulate the paleotectonic stress field. Based on the Griffith and Mohr-Coulomb criterion, the distribution of tectonic fractures in the Shanxi Formation during the Indosinian, Yanshanian, and Himalayan period can be predicted with the index of comprehensive rupture rate. The results show that the acting force of the Pacific Plate and the India Plate to the North China Plate formed the direction of principal stress is N-S, NW - SE, and NE - SW, respectively, in different periods in the study area. Changes in the direction and strength of the acting force led to the regional gradients of tectonic stress magnitude, which resulted in an asymmetrical distribution state of the stress conditions in different periods. It is suggested that the low-stress areas are mainly located in the fault zones and extend along the direction of the fault zones. Furthermore, the high-stress areas are located in the junction of fold belts and the binding site of multiple folds. The development of tectonic fractures was affected by the distribution of stress intensity and the tectonic position of folds and faults, which resulted in some developed areas with level I and II. There are obvious differences in the development of tectonic fractures in the fold and fault zones and the anticline and syncline structure at the same fold zones. The tectonic fractures of the Shanxi Formation during the Himalayan period are more developed than those during the Indosinian and Yanshanian period due to the superposition of the late tectonic movement to the early tectonic movement and the differences in the magnitude and direction of stress intensity.

The Relationship between Fractures and Tectonic Stress Field in the Extra Low-Permeability Sandstone Reservoir at the South of Western Sichuan Depression

The formation and distribution of fractures are controlled by paleotectonic stress field, and their preservative status and effects on development are dominated by the modern stress field. Since Triassic, it has experienced four tectonic movements and developed four sets of tectonic fractures in the extra low-permeability sandstone reservoir at the south of western Sichuan depression. The strikes of fractures are in the S-N, NE-SW, E-W, and NW-SE directions respectively. At the end of Triassic, under the horizontal compression tectonic stress field, for which the maximum principal stress direction was NW.SE, the fractures were well developed near the S-N faults and at the end of NE-SW faults, because of their stress concentration. At the end of Cretaceous, in the horizontal compression stress fields of the NE-SW direction, the stress was obviously lower near the NE-SW faults, thus, fractures mainly developed near the S-N faults. At the end of Neogene-Early Pleistocene, under the horizontal compression tectonic stress fields of E-W direction, stress concentrated near the NE-SW faults and fractures developed at these places, especially at the end of the NE-SE faults, the cross positions of NE-SW, and S-N faults. Therefore, fractures developed mostly near S-N faults and NE-SW faults. At the cross positions of the above two sets of faults, the degree of development of the fractures was the highest. Under the modern stress field of the NW-SE direction, the NW-SE fractures were mainly the seepage ones with tensional state, the best connectivity, the widest aperture, the highest permeability, and the minimum opening pressure.

Experimental and finite element analysis of tibial stress fractures using a rabbit model

AIM: To determine if rabbit models can be used to quantify the mechanical behaviour involved in tibial stress fracture(TSF) development.METHODS: Fresh rabbit tibiae were loaded under compression using a specifically-designed test apparatus. Weights were incrementally added up to a load of 30 kg and the mechanical behaviour of the tibia was analysed using tests for buckling, bone strain and hysteresis. Structural mechanics equations were subsequently employed to verify that the results were within the range of values predicted by theory. A finite element(FE) model was developed using cross-sectional computer tomography(CT) images scanned from one of the rabbit bones, and a static load of 6 kg(1.5 times the rabbit's body weight) was applied to represent running. The model was validated using the experimental strain gauge data, then geometric and elemental convergence tests were performed in order to find the minimum number of cross-sectional scans and elements respectively required for convergence. The analysis was then performed using both the model and the experimental results to investigate the mechanical behaviour of the rabbit tibia under compressive load and to examine crack initiation.RESULTS: The experimental tests showed that un der a compressive load of up to 12 kg, the rabbit tibia demonstrates linear behaviour with little hysteresis Up to 30 kg, the bone does not fail by elastic buckling however, there are low levels of tensile stress which predominately occur at and adjacent to the anterio border of the tibial midshaft: this suggests that fatigue failure occurs in these regions, since bone under cycli loading initially fails in tension. The FE model predic tions were consistent with both mechanics theory and the strain gauge results. The model was highly sensi tive to small changes in the position of the applied load due to the high slenderness ratio of the rabbit s tibia. The modelling technique used in the curren study could have applications in the development o human FE models of bone, where, unlike rabbit tibia the model would be relatively insensitive to very sma changes in load position. However, the rabbit mode itself is less beneficial as a tool to understand the me chanical behaviour of TSFs in humans due to the sma size of the rabbit bone and the limitations of human scale CT scanning equipment.CONCLUSION: The current modelling technique could be used to develop human FE models. However, the rabbit model itself has significant limitations in under standing human TSF mechanics.

3D morphology and formation mechanism of fractures developed by true triaxial stress

As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law and mechanism regarding the influence of the confining pressure constraints on 3D morphological features of natural fractures.First,fracture surfaces were obtained by true triaxial compression test and 3D laser scanning.Then 3D morphological parameters of fractures were calculated by using Grasselli’s model.The results show that the failure mode of granites developed by true triaxial stress can be categorized into tension failure and shear failure.Based on the spatial position of fractures,they can be divided into tension fracture surface,S-1 shear fracture surface,and S-2 shear fracture surface.Micro-failure of the tension fracture surface is dominated by mainly intergranular fracture;the maximum height of asperities on the fracture surface and the 3D roughness of fracture surfaces are influenced by σ_(3) only and they are greater than those of shear fracture surfaces,a lower overall uniformity than tension fracture surface.S-1 shear fracture surface and S-2 shear fracture surface are dominated by intragranular and intergranular coupling fracture.The maximum height of asperities on the fracture surface and 3D roughness of fracture surface are affected by σ_(1),σ_(2),and σ_(3).With the increase of σ_(2) or σ_(3),the cutting off of asperities on the fracture surface becomes more common,the maximum height of asperities and 3D roughness of fracture surface further decrease,and the overall uniformity gets further improved.The experimental results are favorable for selecting technical parameters of enhanced geothermal development and the safety of underground mine engineering.

Analysis of stress fractures in athletes based on our clinical experience

AIM:To analyze stress fractures in athletes based on experience from our sports medicine clinic.METHODS:We investigated the association between stress fractures and age,sex,sports level,sports activity,and skeletal site in athletes seen at our sports medicine clinic between September 1991 and April 2009.Stress fractures of the pars interarticularis were excluded from this analysis.RESULTS:During this period(18 years and 8 mo),14276 patients(9215 males and 5061 females)consulted our clinic because of sports-related injuries,and 263 patients(1.8%)[171 males(1.9%)and 92 females(1.8%)]sustained stress fractures.The average age of the patients with stress fractures was 20.2 years(range 10-46 years);112 patients(42.6%)were 15-19 years of age and 90(34.2%)were 20-24 years of age.Altogether,90 patients(34.2%)were active at a high recreational level and 173(65.8%)at a competitive level.The highest proportion of stress fractures was seen in basketball athletes(21.3%),followed by baseball(13.7%),track and field(11.4%),rowing(9.5%),soccer(8.4%),aerobics(5.3%),and classical ballet(4.9%).The most common sites of stress fractures in these patients were the tibia(44.1%),followed by the rib(14.1%),metatarsal bone(12.9%),ulnar olecranon(8.7%)and pelvis(8.4%).The sites of the stress fractures varied from sport to sport.The ulnar olecranon was the most common stress fracture site in baseball players,and the rib was the most common in rowers.Basketball and classical ballet athletes predominantly sustained stress fractures of the tibia and metatarsal bone.Track and field and soccer athletes predominantly sustained stress fractures of the tibia and pubic bone.Aerobics athletes predominantly sustained stress fractures of the tibia.Middle and long distance female runners who sustained multiple stress fractures had the female athlete triad.CONCLUSION:The results of this analysis showed that stress fractures were seen in high-level young athletes,with similar proportions for males and females,and that particular sports were associated with specific sites for stress fractures.Middle and long distance female runners who suffered from multiple stress fractures had the female athlete triad.

Experimental study on the slip evolution of planar fractures subjected to cyclic normal stress

The frictional rupture mechanisms of rock discontinuities considering the dynamic load disturbance still remain unclear.This paper investigates the transitional behaviors of slip events happened on a planar granite fracture under cyclic normal stress with diferent oscillation amplitudes.The experimental results show that the activations of fast slips always correlate with unloading of normal stress.Besides,the intensive normal stress oscillation can weaken the shear strength which is recoverable when the normal stress return to constant.The rupture patterns are quantifed by stress drop,slip length and slip velocity.With the efect of small oscillation amplitudes,the slip events show chaotic shapes,compared to the regular and predictable style under constant normal stress.When the amplitude is large enough,the big and small slip events emerge alternately,showing a compound slip style.Large amplitude of the cyclic normal stress also widens the interval diferences of the slip events.This work provides experimental supports for a convincible link between the dynamic stress disturbance and the slip behavior of rock fractures.

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and hippocampus.Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology.In this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression.We focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine circuit.We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic system.Therefore,BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Incidence and distribution of stress fractures in recruits during basic training

Stress fracture（SF）in military recruits in China was investigated using99mTc-MDP bone scintigraphy in a randomized sample of 432 injured who wereclinically screened from 1060 recruits during basic training.The relationship between SFand training intensity was discussed.It was shown that the total incidence was 32.5%.There were two peaks during 9 training-weeks:one was in the 2nd week,and the otherin the 7th.Infantry soldiers had a more intensive training and,therefore a higher inci-dence than in artillery and service troops.Although SF was found in most ofweight-bearing bones,tibia was most commonly fractured（67%）.The findings suggestthat SF is a major training-related injury in military recruits and improperly strengthenedtraining can increase the incidence.

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.