Development of an experimental method for well-controlled blast induced traumatic limb fracture in rats

Heterotopic ossification(HO)is a consequence of traumatic bone and tissue damage,which occurs in 65%of military casualties with blast-associated amputations.However,the mechanisms behind blast-induced HO remain unclear.Animal models are used to study blast-induced HO,but developing such models is challenging,particularly in how to use a pure blast wave(primary blast)to induce limb fracture that then requires an amputation.Several studies,including our recent study,have developed platforms to induce limb fractures in rats with blast loading or a mixture of blast and impact loading.However,these models are limited by the survivability of the animal and repeatability of the model.In this study,we developed an improved platform,aiming to improve the animal's survivability and injury repeatability as well as focusing on primary blast only.The platform exposed only one limb of the rat to a blast wave while providing proper protection to the rest of the rat's body.We obtained very consistent fracture outcome in the tibia(location and pattern)in cadaveric rats with a large range of size and weight.Importantly,the rats did not obviously move during the test,where movement is a potential cause of uncontrolled injury.We further conducted parametric studies by varying the features of the design of the platform.These factors,such as how the limb is fixed and how the cavity through which the limb is placed is sealed,significantly affect the resulting injury.This platform and test setups enable well-controlled limb fracture induced directly by pure blast wave,which is the fundamental step towards a complete in vivo animal model for blast-induced HO induced by primary blast alone,excluding secondary and tertiary blast injury.In addition,the platform design and the findings presented here,particularly regarding the proper protection of the animal,have implications for future studies investigating localized blast injuries,such as blast induced brain and lung injuries.

Numerical study on the blocking effect of skin on Flash-Ball Impact and damage assessment

To explore the response law of non-lethal large-size kinetic energy projectiles to blunt attack on skin tissue,and to evaluate the skin injury characteristics of the attacked personnel and the use safety of kinetic energy projectiles.Based on the LS-DYNA simulation software,a three-layer skin simulation model and a Flash-Ball rubber bullet model are established,and the force-time and deformation-time biomechanical corridors of the Flash-Ball rubber bullet impacting human skin tissue are obtained.The corridor curve and the energy transfer and diffusion are analyzed and compared.The safety evaluation of the damage caused by the rubber bullet shooting a human body at different distances is carried out using the empirical formula of the penetration limit.Finally,the safe shooting distance is obtained.The results show that the model used in the simulation has a good correlation with the experimental data,its biomechanical corridor characteristics are different from those of conventional vehicle impact and smallsize projectile response characteristics.The energy transfer and action time of medium and low-speed impact may cause greater damage.The fat layer is the largest energy absorption unit.The minimum safe shooting distance to ensure skin tissue from penetrating damage is 15.8 m,and the limit specific kinetic energy of skin damage is 7.88 J/cm^(2).This study can be extended to the study of biomechanical response law and safety evaluation under the impact of the same type of large kinetic energy projectile,which provides an important theoretical reference for the police to use large kinetic energy projectiles to conduct safe shooting in peacekeeping operations.

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK:a case series

●AIM:To explore the clinical efficacy and safety of stromal lenticule addition keratoplasty(SLAK)with corneal crosslinking(CXL)on patients with corneal ectasia secondary to femtosecond laser-assisted in situ keratomileusis(FS-LASIK).●METHODS:A series of 5 patients undertaking SLAK with CXL for the treatment of corneal ectasia secondary to FS-LASIK were followed for 4-9mo.The lenticules were collected from patients undertaking small incision lenticule extraction(SMILE)for the correction of myopia.Adding a stromal lenticule was aimed at improving the corneal thickness for the safe application of crosslinking and compensating for the thin cornea to improve its mechanical strength.●RESULTS:All surgeries were conducted successfully with no significant complications.Their best corrected visual acuity(BCVA)ranged from 0.05 to 0.8-2 before surgery.The pre-operational total corneal thickness ranged from 345-404μm and maximum keratometry(Kmax)ranged from 50.8 to 86.3.After the combination surgery,both the corneal keratometry(range 55.9 to 92.8)and total corneal thickness(range 413-482μm)significantly increased.Four out of 5 patients had improvement of corneal biomechanical parameters(reflected by stiffness parameter A1 in Corvis ST).However,3 patients showed decreased BCVA after surgery due to the development of irregular astigmatism and transient haze.Despite the onset of corneal edema right after SLAK,the corneal topography and thickness generally stabilized after 3mo.●CONCLUSION:SLAK with CXL is a potentially beneficial and safe therapy for advanced corneal ectasia.Future work needs to address the poor predictability of corneal refractometry and compare the outcomes of different surgical modes.

Mechanisms of shoulder trauma: Current concepts

Acute traumatic injuries to the glenohumeral articulation are common.The types of injuries depend on age,muscle strength,bone density,and biomechanics of the traumatic event.Understanding the different mechanisms of trauma and how they affect the functional anatomical structures of the shoulder joint is crucial for the treatment of these lesions.Therefore,when clinicians have knowledge of these mechanisms they can accurately diagnose and treat shoulder pathology and predict distinct injury patterns.Here,we have described the fundamentals of the mechanisms of injury of the glenohumeral dislocation,dislocation with fracture of the humeral head,and the proximal humerus fracture.We have focused on common injury mechanisms and the correlation with radiological diagnostics.Radiological and laboratory findings of distinct types of injury were also discussed.

Indirect contact matters:Mid-flight external trunk perturbation increased unilateral anterior cruciate ligament loading variables during jump-landings

Purpose:To determine the effect of unanticipated mid-flight medial-lateral external perturbation of the upper or lower trunk on anterior cruciate ligament(ACL)loading variable s during jump-landings.Methods:Thirty-two participants performed double-leg vertical jump-landings while bilateral kinematics and kinetics were collected under 6conditions(upper or lower trunk perturbation locations;no,left,or right perturbation directions).Two customized catapult apparatuses were created to apply pushing perturbation to participants near the maximal jump height.Results:The ball contacted participants near the center of mass for the lower-trunk conditions and approximately 23 cm above the center of mass for the upper-trunk conditions.Under upper-trunk perturbation,the contralateral leg demonstrated significantly smaller knee flexion angles at initial contact and greater peak knee abduction angles,peak vertical ground reaction forces,peak knee extension moments,and peak knee adduction moments compared to other legs among all conditions.Under lower-trunk perturbation,the contralateral leg showed significantly smaller knee flexion angles at initial contact and increased peak vertical ground reaction forces and peak knee extension moments compared to legs in the no-perturbation conditions.Conclusion:Mid-flight external trunk pushing perturbation increased ACL loading variables for the leg contralateral to the perturbation.The uppertrunk perturbation resulted in greater changes in ACL loading variables compared to the lower-trunk perturbation,likely due to trunk and ipsilateral leg rotation and more laterally located center of mass relative to the contralateral leg.These findings may help us understand the mechanisms of indirect-contact ACL injuries and develop jump-landing training strategies under mid-flight trunk perturbation to better prevent ACL injury.

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.

A lateral ankle sprain during a lateral backward step in badminton:A case report of a televised injury incident

Background:This study presents a kinematic analysis of an acute lateral ankle sprain incurred during a televised badminton match.The kinematics of this injury were compared to those of 19 previously reported cases in the published literature.Methods:Four camera views of an acute lateral ankle sprain incurred during a televised badminton match were synchronized and rendered in3-dimensional animation software.A badminton court with known dimensions was built in a virtual environment,and a skeletal model scaled to the inj ured athlete’s height was used for skeletal matching.The ankle joint angle and angular velocity profiles of this acute injury were compared to the summarized findings from 19 previously reported cases in the published literature.Results:At foot strike,the ankle joint was 2° everted,33° plantarflexed,and 18° internally rotated.Maximum inversion of 114° and internal rotation of 69° was achieved at 0.24 s and 0.20 s after foot strike,respectively.After the foot strike,the ankle joint moved from an initial position of plantarflexion to dorsiflexion-from 33° plantarflexion to 53° dorsiflexion(range=86°).Maximum inversion,dorsiflexion,and internal rotation angular velocity were 1262°/s,961°/s,and 677°/s,respectively,at 0.12 s after foot strike.Conclusion:A forefoot landing posture with a plantarflexed and internally rotated ankle joint configuration could incite an acute lateral ankle sprain injury in badminton.Prevention of lateral ankle sprains in badminton should focus on the control and stability of the ankle joint angle during forefoot landings,especially when the athletes perform a combined lateral and backward step.

Examining the intrinsic foot muscles'capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping

Background:During human locomotion,a sufficiently stiff foot allows the ankle plantar flexors to generate large propulsive powers.Increasing foot stiffness(e.g.,via a carbon plate)increases the ankle’s external moment arm in relation to the internal moment arm(i.e.,increasing gear ratio),reduces plantar flexor muscles’shortening velocity,and enhances muscle force production.In contrast,when activation of the foot’s intrinsic muscles is impaired,there is a reduction in foot and ankle work and metatarsophalangeal joint stiffness.We speculated that the reduced capacity to actively control metatarsophalangeal joint stiffness may impair the gearing function of the foot at the ankle.Methods:We used a tibial nerve block to examine the direct effects of the intrinsic foot muscles on ankle joint kinetics,in vivo medial gastrocnemius’musculotendinous dynamics,and ankle gear ratio on 14 participants during maximal vertical jumping.Results:Under the nerve block,the internal ankle plantar flexion moment decreased(p=0.004)alongside a reduction in external moment arm length(p=0.021)and ankle joint gear ratio(p=0.049)when compared to the non-blocked condition.Although medial gastrocnemius muscle-tendon unit and fascicle velocity were not different between conditions,the Achilles tendon was shorter during propulsion in the nerve block condition(p<0.001).Conclusion:In addition to their known role of regulating the energetic function of the foot,our data indicate that the intrinsic foot muscles also act to optimize ankle joint torque production and leverage during the propulsion phase of vertical jumping.

Quantification of Ride Comfort Using Musculoskeletal Mathematical Model Considering Vehicle Behavior

This research aims to quantify driver ride comfort due to changes in damper characteristics between comfort mode and sport mode,considering the vehicle’s inertial behavior.The comfort of riding in an automobile has been evaluated in recent years on the basis of a subjective sensory evaluation given by the driver.However,reflecting driving sensations in design work to improve ride comfort is abstract in nature and difficult to express theoretically.Therefore,we evaluated the human body’s effects while driving scientifically by quantifying the driver’s behavior while operating the steering wheel and the behavior of the automobile while in motion using physical quantities.To this end,we collected driver and vehicle data using amotion capture system and vehicle CAN and IMU sensors.We also constructed a three-dimensional musculoskeletal mathematical model to simulate driver movements and calculate the power and amount of energy per unit of time used for driving the joints and muscles of the human body.Here,we used comfort mode and sport mode to compare damper characteristics in terms of hardness.In comfort mode,damper characteristics are soft and steering stability is mild,but vibration from the road is not easily transmitted to the driver making for a lighter load on the driver.In sport mode,on the other hand,damper characteristics are hard and steering stability is comparatively better.Still,vibration from the road is easily transmitted to the driver,whichmakes it easy for a load to be placed on the driver.As a result of this comparison,it was found that a load was most likely to be applied to the driver’s neck.This result in relation to the neck joint can therefore be treated as an objective measure for quantifying ride comfort.

Biomechanical Response of the Root System in Tomato Seedlings under Wind Disturbance

Wind disturbance as a green method can effectively prevent the overgrowth of tomato seedlings,and its mechanism may be related to root system mechanics.This study characterized the biophysical mechanical properties of taproot and lateral roots of tomato seedlings at five seedling ages and seedling substrates with three different moisture content.The corresponding root system-substrate finite element(FE)model was then developed and validated.The study showed that seedling age significantly affected the biomechanical properties of the taproot and lateral roots of the seedlings and that moisture content significantly affected the biomechanical properties of the seedling substrate(p<0.05).The established FE model was sensitive to wind speed,substrate moisture content,strong seedling index,and seedling age and was robust.The multiple linear regression equations obtained could predict the maximum stress and strain of the root system of tomato seedlings in the wind field.The strong seedling index had the greatest impact on the biomechanical response of the seedling root system during wind disturbance,followed by wind speed.In contrast,seedling age had no significant effect on the biomechanical response of the root system during wind disturbance.In the simulation,no mechanical damage was observed on the tissue of the seedling root system,but there were some strain behaviors.Based on the plant stress resistance,wind disturbance may affect the growth and development of the root system in the later growth stage.In this study,finite element and statistical analysis methods were combined to provide an effective approach for indepth analysis of the biomechanical mechanisms of wind disturbances that inhibit tomato seedlings’growth from the root system’s perspective.

Agreement of intraocular pressure measurement with Corvis ST,non-contact tonometer,and Goldmann applanation tonometer in children with ocular hypertension and related factors

AIM:To access the agreement of intraocular pressure(IOP)values obtained from biomechanically corrected tonometer[Corvis ST(CST)],non-contact tonometer(NCT),and Goldmann applanation tonometer(GAT)in children with NCT measured-IOP(NCT-IOP)values of 22 mm Hg or more,and related factors.METHODS:A total of 51 eyes with NCT-IOP≥22 mm Hg in children aged 7 to 14y were examined and IOP was measured by CST,NCT,and GAT.Based on GAT measured IOP(GAT-IOP),ocular hypertension(OHT)group(≥22 mm Hg,24 eyes)and the non-OHT group(<22 mm Hg,27 eyes)were defined.We compared the agreement of the three measurements,i.e.,CST measured IOP(CST-IOP),GAT-IOP,and NCT-IOP,and further analyzed the correlation between the differences in tonometry readings,central corneal thickness(CCT),axial length(AL),optic disc rim volume,and age.RESULTS:Compared with the OHT group,thicker CCT,larger rim volume,and higher differences between NCTIOP and GAT-IOP,were found in the non-OHT group.The differences between CST-IOP and GAT-IOP were lower than the differences between NCT-IOP and GAT-IOP in both groups.The mean differences in CST-IOP and GAT-IOP were 1.26 mm Hg(95%limit of agreement ranged from 0.1 to 2.41 mm Hg,OHT group)and 1.20 mm Hg(95%limit of agreement ranged from-0.5 to 3.00 mm Hg,non-OHT group),and the mean differences in NCT and GAT were 3.90 mm Hg(95%limit of agreement ranged from-0.19 to 9.70 mm Hg,OHT group)and 6.00 mm Hg(95%limit of agreement ranged from 1.50 to 10.50 mm Hg,non-OHT group).The differences between CST-IOP and GAT-IOP were not related to CCT,age,and AL in both groups;while the differences between NCT-IOP and GAT-IOP were related to CCT in the OHT group(r=0.93,P<0.001)and to CCT and AL in the non-OHT group(r=0.66,P<0.001,r=-0.81,P<0.001).CONCLUSION:The accuracy of NCT in the diagnosis of pediatric OHT is low.The agreement of CST-IOP and GATIOP was significantly higher in children with and without OHT than in those with NCT-IOP and GAT-IOP.Therefore,CST can be used as a good alternative for IOP measurement in children.The impacts of CCT and AL on NCT measurement need to be fully considered when managing childhood IOP.

Rotator cuff repair with an interposition polypropylene mesh:A biomechanical ovine study

BACKGROUND Chronic large to massive rotator cuff tears are difficult to treat and re-tears are common even after surgical repair.We propose using a synthetic polypropylene mesh to increase the tensile strength of rotator cuff repairs.We hypothesize that using a polypropylene mesh to bridge the repair of large rotator cuff tears will increase the ultimate failure load of the repair.AIM To investigate the mechanical properties of rotator cuff tears repaired with a polypropylene interposition graft in an ovine ex-vivo model.METHODS A 20 mm length of infraspinatus tendon was resected from fifteen fresh sheep shoulders to simulate a large tear.We used a polypropylene mesh as an interposition graft between the ends of the tendon for repair.In seven specimens,the mesh was secured to remnant tendon by continuous stitching while mattress stitches were used for eight specimens.Five specimens with an intact tendon were tested.The specimens underwent cyclic loading to determine the ultimate failure load and gap formation.RESULTS The mean gap formation after 3000 cycles was 1.67 mm in the continuous group,and 4.16 mm in the mattress group(P=0.001).The mean ultimate failure load was significantly higher at 549.2 N in the continuous group,426.4 N in the mattress group and 370 N in the intact group(P=0.003).CONCLUSION The use of a polypropylene mesh is biomechanically suitable as an interposition graft for large irreparable rotator cuff tears.

Effects of alendronate on bone mass and organ pathology in ovariectomized mice

Objective:To investigate the effect of alendronate on bone mass and organ pathology of ovariectomized mice.Methods:Thirty SPF grade C57 female mice were randomly divided into three groups(n=10):Sham operation group(Sham),ovariectomized group(OVX)and ovariectomized+alendronate group(ALN).The sodium alendronate was injected subcutaneously at 400μg/kg twice a week in the ALN group.The equal volume of normal saline was injected subcutaneously twice a week in the SHAM group and OVX group.After 12 weeks of drug administration,the samples were taken.The organ coefficients,main organ pathological sections,and bone histopathological sections were observed,and the micro CT,L4 biomechanics and serum biochemical indicators were analyzed.Results:The uterine coefficient of Sham group was(0.0054±0.0007)significantly higher than that of OVX group(0.0026±0.0009)and ALN group(0.0025±0.0007),and the difference was statistically significant(P<0.05).No obvious lesions or toxic or side effects were observed in the main organs.Compared with the OVX group,the ALN group with decalcified sections of bone tissue had compact trabecular structure and fewer adipocytes.Micro-CT results showed that the Tb.BMD,Tb.N,Tb.Th and Tb.BV/TV values of the ALN group were significantly increased compared with those of the OVX group,but the Tb.Sp value was significantly decreased,and the difference was statistically significant(P<0.05).In L4 vertebral body biomechanics,the elastic modulus(50.29±13.43)and maximum load number(29.83±4.92)of ALN group were significantly higher than those of OVX group(14.77±3.12)and maximum load number(11.57±3.18),and the difference was statistically significant(P<0.05).Compared with the OVX group,the serum OCN and PINP indicators of bone formation in the ALN group were increased,while the bone resorption indicators TRACP-5b and CTX-I were decreased,with statistical significance(P<0.05).Conclusion:Alendronate sodium improves bone quality by increasing bone density,improving bone microstructure,increasing bone strength,promoting bone formation and inhibiting bone resorption,without obvious toxic and side effects on organs.

Changes in corneal biomechanics and posterior corneal surface elevation after FS-LASIK

AIM:To investigate the changes in corneal biomechanics and posterior corneal surface elevation after femtosecond laser-assisted in situ keratomileusis(FS-LASIK).METHODS:Totally 197 eyes of 100 patients who underwent the FS-LASIK from April 2022 to November 2022 were included.They were divided into three groups according to the ratio of residual corneal stroma thickness/corneal thickness(RCST/CT):Group I(50%≤RCST/CT<55%,63 eyes of 32 patients),Group II(55%≤RCST/CT<60%,67 eyes of 34 patients),and Group III(RCST/CT≥60%,67 eyes of 34 patients).The intraocular pressure(IOP),corneal compensated IOP(IOPcc),corneal hysteresis(CH)and corneal resistance factor(CRF)were measured immediately,1,and 3mo postoperatively by ocular response analyzer(ORA)and the posterior elevation difference(PED)was measured by Pentacam.RESULTS:After operation,IOP,CH,CRF,and PED were statistically different among the three groups(F=12.99,31.148,23.998,all P<0.0001).There was no statistically significant difference in IOPcc among the three groups(F=0.603,P>0.05).The IOP,IOPcc,CH,and CRF were statistical changed after surgery(F=699.635,104.125,308.474,640.145,all P<0.0001).The PED of Group I was significantly higher than that of Group II(P<0.05),and Group II was significantly higher than that of Group III(P<0.05).The PED value of 3mo after surgery decreased in each group compared with 1mo after surgery,but there was no statistical difference(Group I:t=0.82,P=0.41;Group II:t=0.17,P=0.87;Group III:t=1.35,P=0.18).The correlation analysis of corneal biomechanical parameter changes with PED at 1mo and 3mo after surgery showed thatΔIOP,ΔIOPcc,ΔCH,andΔCRF were not correlated with PED value in three groups(P>0.05).CONCLUSION:The smaller the RCST/CT,the greater effect on corneal biomechanics and posterior surface elevation.There is no correlation between changes in corneal biomechanics and posterior corneal surface elevation in the range of RCST/CT≥50%.

Mechanical analysis of the femoral neck dynamic intersection system with different nail angles and clinical applications

BACKGROUND The femoral neck dynamic intersection system(FNS)is mechanically more stable than other internal fixation techniques.Current studies have confirmed that the structural design of FNS has good biomechanical properties in European and American populations.However,whether the suitability of the FNS's 130°main nail angle design for Asian populations has been thoroughly investigated remains unclear.AIM To compare the biomechanical stability differences among different main nail angles of the FNS in the treatment of femoral neck fractures in Asian populations.METHODS Computed tomography data of the femur of healthy adult male volunteers were imported into Mimics software to create a three-dimensional model of the femur.The model was adapted to the curve using Geomagic software and imported into Solidworks software to construct the Pauwels I femoral neck fracture model and design the FNS internal fixation model using different main nail angles.Afterward,the models were assembled with the FNS fracture model and meshed using the preprocessing Hypermesh software.Subsequently,they were imported into Abaqus software to analyze and evaluate the biomechanical effects of different angles of the FNS main nail on the treatment of femoral neck fractures.RESULTS The peak displacement of the proximal femur under different angles of FNS fixation under stress was 7.446 millimeters in the 120°group and 7.416 millimeters in the 125°group;in the 130°,135°,and 140°FNS fixation groups,the peak displacement was 7.324 millimeters,8.138 millimeters,and 8.246 millimeters,respectively.In the 120°and 125°FNS fixation groups,the maximum stresses were concentrated at the main nail and the anti-rotation screw,which intersected the fracture line of the femur neck,resulting in peak stresses of 200.7 MPa and 138.8 MPa,respectively.Peak stresses of 208.8 MPa,219.8 MPa,and 239.3 MPa were observed on the angular locking plate distal to the locking screw in the 130°,135°,and 140°fixation groups.CONCLUSION FNS has significant stress distribution properties,a minimal proximal femoral displacement,and an optimal stability for treating femoral neck fractures in Asian populations when performed with a 130°main nail angle.

Pregnancy-Induced Changes in Ocular Biomechanics Are Related to Maternal Hormone Levels in Healthy Chinese Pregnant Women

Background: To explore the changes in ocular biomechanics during pregnancy and the postpartum period and their association with maternal hormone level changes. Methods: In a prospective cohort study, 24 eyes of 12 pregnant women were enrolled and monitored throughout pregnancy and after delivery (6 weeks). Intraocular pressure (IOP), central corneal thickness (CCT), corneal endothelium cell (CEC), axial length (AL), corneal curvature (K1, K2), anterior chamber depth (ACD), central subfield thickness (CST), macular volume (MV), cube average thickness (CAT), retinal nerve fibre layer (RNFL), tear meniscus height (TMH), and breaking up time (BUT) were measured throughout pregnancy, and blood plasma levels of maternal hormones were determined at the same time points. Results: A gradual decrease in IOP values was observed as gestation progressed, and there was a statistically significant difference in IOP between the 3rd trimester and the 1st and 2nd trimester and postpartum (p = 0.002, p = 0.006, p = 0.050). There was a significant difference between the 1st and 2nd trimesters in terms of MV (p = 0.023). The difference in RNFL in the 3rd trimester and postpartum was significant (p = 0.011). The levels of the β-hCG showed a significant correlation with K2, ACD, and TMH only in the 2nd trimester (r = 0.588, p = 0.045;r = - 0.740, p = 0.006;r = 0.642, p = 0.024). Regarding luteinizing hormone, there was a negative correlation with MV in the 1st and 2nd trimesters (r = - 0.598, p = 0.040;r = - 0.672, p = 0.017) and CAT in the 1st and 2nd trimesters (r = - 0.599, p = 0.040;r = - 0.655, p = 0.021). Luteinizing hormone levels were correlated with ACD (r = - 0.702, p = 0.011) in the 2nd trimester and K2 (r = 0.585, p = 0.046) in the 3rd trimester. A correlation was found between follicle-stimulating hormone levels and CEC, MV and CAT in the 1st trimester (r = - 0.677, p = 0.016;r = - 0.602, p = 0.039;r = - 0.584, p = 0.046) and AL in the 3rd trimester (r = - 0.618, p = 0.032). The correlation between oestradiol and CST in the 1st trimester (r = - 0.621, p = 0.031) and RNFL (r = 0.594, p = 0.041) in the postpartum. A statistically significant correlation between progesterone and MV (r = 0.583, p = 0.047) and TMH (r = 0.762, p = 0.004) was observed in the 1st trimester. No significant intergroup correlation was observed postpartum (p > 0.05). Conclusion: Ophthalmological parameters showed physiological changes induced by hormone levels in pregnancy and returned to baseline levels after delivery.

Effect of cervical spine surgery on the biomechanics of the cervical spine

In clinical practice,cervical spine surgery inevitably alters the original physiological structure of the cervical spine,thus causing changes in the original biomechanical properties of the cervical spine.The biomechanical properties of the cervical spine are particularly significant as it is an essential structure that supports the head and connects the trunk.Different cervical spine surgery options can have different effects on the biomechanics of the cervical spine.Therefore,this review will discuss recent research advances on the effects of cervical spine surgery on cervical spine biomechanics.We hope that this review will provide some theoretical basis for future studies on the biomechanical effects of cervical spine surgery on the cervical spine.

种植体的应力应变分析及优化设计

采用有限法对种植体进行应力应变研究,为临床设计和选择最佳的结构参数提供理论依据。基于实验建立种植体有限元模型,对其结构尺寸参数设定尺寸变化范围,施加垂直向和水平向的载荷,观察种植体平均应力峰值的变化。基于有限元分析种植体的结构优化提高了结构的生物力学性能。

基于生物力学数值模型对鼻腔气流场、温度场的研究

鼻腔除呼吸功能外,还有调节吸入气体温度、流量等作用。若空气未经过鼻腔加温作用,下呼吸道正常生理功能就会受到损害,并容易招致感染。在肺部进行气体交换的空气温度过低会导致肺部疾病。正常鼻腔对空气的加温使冷空气在温度上接近体温。鼻腔病变时,鼻腔气流阻力产生相应的变化,鼻腔气流场也发生相应变化。鼻腔通气功能异常可以引起鼻科疾病,甚至其他系统疾患。因此,对鼻腔气流场、温度场的研究有一定的临床意义。

Biomechanics of sclera crosslinked using genipin in rabbit

AIM:To strengthen the biomechanics of collagen by crosslinking rabbit scleral collagen with genipin to develop a new therapy for preventing myopic progression. METHODS:Ten New Zealand rabbits were treated with 0.5 mmol/L genipin injected into the sub-Tenon's capsule in the right eyes. Untreated contralateral eyes served as the control. The treated area was cut into scleral strips measuring 4.0 mm×10.0 mm for stress-strain measurements(n=5). The remaining five treated eyes were prepared for histological examination.RESULTS:Compared to the untreated scleral strips,the genipin-crosslinked scleral strips showed that the ultimate stress and Young's modulus at 10% strain were increased by the amplitude of 130% and 303% respectively,ultimate strain was decreased by 24%. There had no α-smooth muscle actin(α-SMA)positive cells in control and treated sclera. Histologically,there was no sign of apoptosis in the sclera,choroid,and retina; and no side effects were found in the peripheral cornea and optic nerve adjacent to the treatment area.CONCLUSION:Genipin induced crosslinking of collagen can increase its biomechanical behavior by direct strengthening of the extracellular matrix in rabbit sclera,with no α-SMA expression seen in the myofibroblasts. As there is no evidence of cytotoxicity in the scleral,choroidal,and retinal cells,genipin is likely a promising agent to strengthen the weakened sclera to prevent myopic progression.