| 1.BackgroundAcute lateral ankle sprain(ALAS)is one of the common diseases in emergency orthopedics and orthopedics.It is often caused by the failure of treatment and mistreatment,which eventually leads to the delay of the disease.The probability of recurrent sprain in ALAS patients is as high as 74%within one year,and about 30%of them will repeatedly sprain and eventually develop into functional ankle instability(FAI),which brings serious problems to patients.Due to the limitations of physical examination and the patient’s resistance to pain,clinicians are affected to carry out risk stratification and prognosis evaluation for this group.Traditional Chinese medicine continues to inherit and innovate in the research of disease prognosis,and adheres to the idea of "prevention of disease",which coincides with the concept of modern preventive medicine.At present,the research on risk factors related to ALAS is complicated and the research results lack systematic sorting,which seriously affects the overall risk assessment of ALAS population by doctors.At the same time,there is a lack of research on the prognosis of ALAS,and the evaluation tool for systematically evaluating the risk of poor prognosis of ALAS has not been built.Therefore,the construction of a scientific and effective clinical prognosis model of ALAS can help clinicians quantify the condition,evaluate the prognosis,allocate medical resources reasonably and reduce the occurrence of adverse prognostic events in ALAS,which has certain practical significance.Seeking the root of the disease is the leading thought of the disease treatment in the traditional Chinese medicine,and the "prevent the recurrence of disease" of the theory of "prevention of disease" is the embodiment of seeking the root of the disease.The research on the mechanism of ALAS mainly has the following disputes:whether ALAS is closely related to ankle metatarsal flexion and back extension.whether metatarsal flexion exists as a sufficient condition for ALAS.Which state of metatarsal flexion or back extension is more prone to ALAS.According to the traditional view,ALAS is caused by the sudden varus,pronation and metatarsal flexion of the ankle joint,and none of them is indispensable.However,modern research has found that ALAS is mainly caused by varus and Internal rotation,especially Internal rotation,which has little relationship with metatarsal flexion and back extension of ankle joint.In the early stage,the research group has completed the construction and verification of the normal ankle finite element model,and simulated the stress distribution around the ankle during the gait cycle.Based on the above controversies,the research group proposed that the main influencing factors of ALAS injury mechanism are ankle varus and Internal rotation,and metatarsal flexion and dorsal extension are secondary factors.2.ObjectiveUnder the guidance of the theory of "prevention of disease",identify the risk factors related to ALAS,construct the clinical prognosis model of ALAS,and develop an APP which can calculate the prognostic risk of ALAS,In order to guide the prognosis of the disease,achieve the goal of "treat diseases that do not occur,are not serious,and do not affect other organs".Build the finite element model of ankle joint,simulate the different working conditions of ALAS,compare and analyze the strain of lateral ligament of ankle joint under different working conditions of ALAS,clarify the injury mechanism of ALAS patients,play the role of "prevent the recurrence of disease "and seek the root of the disease,and provide theoretical support and scientific guidance for the prevention and treatment of ALAS.3.Method(1)Screening of Internal Risk Factors Related to the Prognosis of ALASThrough systematic review and meta-analysis,relevant literatures on risk factors of ALAS were screened.The included factors were analyzed and summarized,and the high risk factors related to ALAS were preliminarily obtained.Based on the preliminary screening of ALAS-related high-risk factors through meta-analysis and systematic evaluation in the early stage,an expert questionnaire on ALAS high-risk factors was initially prepared.Delphi method was used to optimize the items of the questionnaire and finally form the "ALAS risk factor questionnaire".(2)Establishment and Validation of prognostic model for ALASThrough a retrospective cohort study,based on the "ALAS risk factors questionnaire" determined by literature research,the information of ALAS patients diagnosed in emergency orthopedics and joint departments of Wangjing hospital from September 2020 to March 2022 was collected.According to the inclusion and exclusion criteria,the clinical sample data set was determined.A telephone follow-up was conducted 12 months after the sprain to determine whether there was acute lateral ankle joint sprain again or FAI.First,the clinical sample data set was randomly divided into training set(70%)and validation set(30%).According to whether acute lateral ankle sprain occurred,it was divided into sprain group and normal group.The risk factors of ALAS determined by literature research were analyzed by single factor and multiple factor logistic regression,and the prognosis model of Acute lateral ankle joint Re-sprain was constructed.Then,based on the data set diagnosed as acute lateral ankle Re-sprain,it was divided into training set and verification set according to 7:3 proportion,and divided into instability group and sprain group according to the diagnostic criteria of FAI.The risk factors of FAI within 12 months of acute lateral ankle sprain were identified and the prognosis model was constructed.The effectiveness of the model was verified by the area under the subject working characteristic curve and Hosmer-Lemeshow test,and the clinical application value of the prognostic model was tested by internal verification.Clinical validation of factors included in ALAS prognosis model:The information of patients with ALAS diagnosed in our hospital from August 2022 to October 2022 was collected and studied by random control method.The experimental group was treated with traditional Chinese medicine external treatment(Xiaotong plaster)and routine treatment,while the control group was treated with routine treatment.The sample size was calculated according to the results of literature research.The observation period of this study was 6 weeks and was followed up every 2 weeks.The two treatment schemes are commonly used in clinic,and the smooth implementation of this project can be ensured by obtaining the corresponding case data through perfect clinical observation and follow-up.The quantifiable risk factors included in the prognostic model are used as observation indicators,including 5 indicators such as VAS score,ankle range of motion,and Y-balance test.SPSS23.0 software was used to compare the differences within and between groups to further verify the clinical reliability of the prognostic model.(3)Biomechanical Injury Mechanism of ALASFirst of all,based on the CT and MRI images of volunteers’ feet and ankles,the shape of normal ankles was restored by 3D modeling software,and the preliminary models were imported into the finite element simulation software ABAQUS and ANSYS software for post-processing analysis.Then,with the currently recognized Anderson ankle finite element as the control,the model constructed in this study is compared and analyzed with the Anderson ankle finite element,and the scientific validity is verified by collecting the stress data at different points of the normal ankle finite element model and the constructed ALAS finite element model.Finally,the ANSYS software is used to simulate the ankle varus moment and internal rotation moment loaded under different metatarsal flexion and dorsal extension angles of the ankle joint,to maximize the strain of the ligament during the reduction of ALAS,to compare the stress of the ligament under different working conditions,and to comprehensively analyze the biomechanical mechanism of ALAS.4.Result(1)Screening The Internal Risk Factors Related to the Prognosis of ALASMeta-analysis and systematic review included 32 articles with a total of 7548 patients,and the quality of the literature was good.According to the characteristics of the literature,13 risk factors can be included and perform meta-analysis,including general condition(sex,age,height,weight,BMI,history of sprain),physical examination(pain,ankle relaxation,balance and posture control,ankle range of motion(metatarsal flexion,dorsal extension,Ankle valgus,Varus malleolus)).Combined with literature review and clinical experience,three high risk factors of ecchymosis,muscle strength and anterior drawer test were added.Balance and posture control were divided into dynamic balance and static balance,and 17 high risk factors related to ALAS were included.On the basis of meta-analysis and systematic evaluation of the risk factors related to ALAS,the risk factors related to ALAS were identified based on Delphi method,including 18 risk factors including age,sex,weight,BMI,sprain history,continued high load after sprain,swelling,VAS score,metatarsal flexion,back extension,front drawer test,talus tilt test,static balance,dynamic balance,valgus-varus muscle strength,medial ankle space,tibiofibular space,talus tilt angle,The ALAS risk factor questionnaire with high authority and credibility has been formed.(2)Establishment and Validation of prognostic model for ALASFinally,300 patients with ALAS were included.Among them,there were 190 patients with acute lateral ankle Re-sprain within 12 months,and 80 patients with FAI were diagnosed.Clinical prognostic models were constructed,and internal verification was completed.Risk prediction APP was developed at the same time.Based on the data set of 300 cases of ALAS,BMI,the number of ALAS in 12 months,Continuous high-load activity after sprain,and the Foot Lift Test are the risk factors of acute lateral ankle Re-sprain,while the active back extension angle and the active metatarsal flexion angle of the ankle are the protective factors of acute lateral ankle sprain.The prognosis model of acute lateral ankle Re-sprain is constructed.The model AUC(0.898,95%CI:0.849～0.947,P<0.05),Hosmer-Lemeshow test(χ2=11.36,P>0.05).Through stepwise regression analysis of 190 cases of acute lateral ankle sprain,it was concluded that BMI,the number of ALAS in 12 months,the length of tibiofibular space,and Foot Lift Test were the risk factors of FAI,while the active metatarsal flexion angle of ankle joint and Y-balance Test were the protective factors of FAI.According to the weight of predictive factors,the prognostic model of FAI was constructed.The Distinguishing degree test of the prognostic model was AUC(0.898,95%CI:0.841～0.955,P<0.05)and Hosmer-Lemeshow test(χ2=12.35,P>0.05).The clinical verification based on the external treatment of traditional Chinese medicine showed that the intra-group analysis showed that at Follow-up nodes after treatment,the VAS score,AOFAS score,Y-balance Test,Foot Lift Test and ankle joint activity of the test group and the control group were significantly improved compared with those before treatment,P<0.001,with statistical difference.The results of inter-group comparison showed that there were significant differences between the test group and the control group in VAS score(before 4 weeks),ankle motion,ankle static stability and overall functional recovery(P<0.05),which also has the significant differences.The comprehensive results show that the clinical prognosis model of ALAS is reasonable and reliable,which has strong clinical applicability.(3)Biomechanical Injury Mechanism of ALASThe normal finite element model of ankle joint includes 212004 elements and 781518 nodes,while the ALAS finite element model includes 233401 elements and 586395 nodes.In the neutral operating condition,the Von Mises stress of the ligament is mainly concentrated at the insertion point of the posterior tibial ligament,which is 10.35±0.07Mpa,and the Von Mises stress of the bone is concentrated at the neck of the talus,which is 7.29±0.11Mpa.The Von Mises stress under ALAS condition changes,mainly at the starting point of the anterior talofibular ligament,which is 10.21±0.07Mpa.The Von Mises stress of bone is concentrated at the talus neck and the medial malleolus joint surface,and the maximum Von Mises stress is 10.23±0.27Mpa.Von Mises stress of lateral collateral ligament,talus neck and medial malleolus talus joint surface of ALAS model was significantly higher than that of normal ankle joint model in neutral position(P<0.05),with statistical significance.Based on the normal ankle joint finite element model,a total of 200 ALAS finite element models under different varus and internal rotation combinational conditions are constructed through different load loads,including neutral position inversion,varus and internal rotation conditions(25);metatarsal flexion,varus and internal rotation conditions(100);Dorsal extension,varus and internal rotation conditions(75).Under the condition of constant moment of varus and internal rotation of tibia,with the increase of metatarsal flexion angle,the strain value of anterior talofibular ligament increased gradually.The maximum strain of ligament occurred in the comprehensive condition of metatarsal flexion 40°,varus and tibial internal rotation moment 20Nm.The starting strain value of anterior talofibular ligament was 0.436,and the fibula attachment area of anterior talofibular ligament was broken.When the moment of varus and tibial pronation are both greater than 15Nm,the strain value of the anterior talofibular ligament is all greater than 30%,which is in a broken state,independent of the plantar flexion angle.However,with the increase of metatarsal flexion angle,the strain of calcaneus-fibular ligament decreases gradually,and only a few cases show calcaneofibular ligament rupture(Metatarsal flexion 20°,loaded varus moment 10Nm,tibial internal rotation moment 15Nm,varus moment 15Nm,tibial internal rotation moment 5Nm).When the varus moment and the internal rotation moment of the tibia were fixed,the anterior talofibular ligament decreased with the increase of the dorsal extension angle of the ankle joint,and the calcaneofibular ligament showed an increasing trend as a whole.With the loading of varus moment and tibial internal rotation moment,the calcaneus-fibular ligament began to be damaged or even broken when the moment loading≥15Nm.The calcaneal and fibular ligaments were broken under different working conditions from 0° to 30° during back extension loading,while the calcaneal and fibular ligaments were only damaged and not broken during Metatarsal flexion loading from 0° to 40°.When the ankle joint is extended,the strain load of the anterior talofibular ligament is greater than 20%under static condition when the ankle varus moment and tibial internal rotation moment≥15Nm.The angle of metatarsal flexion and dorsal extension is constant,and with the loading of varus and internal rotation moment,the strain value of lateral collateral ligament is positively correlated with the magnitude of torque loading.No matter in any range of ankle metatarsal flexion,the lateral collateral ligament may be injured with the loading of varus and internal rotation moment.The ankle dorsal extension condition can also lead to the injury of the lateral collateral ligament.The torque required for the injury of lateral collateral ligament in metatarsal flexion condition is less than that in dorsal extension condition.5.Conclusion(1)In this study,we constructed the ALAS prognosis model of recurrent sprain or even FAI within 12 months after ALAS and completed the internal verification.And we also developed the ALAS prognostic risk APP.Completed the overall risk assessment and risk stratification of the ALAS population,can detect high-risk individuals and reduce the occurrence of adverse events.(2)Based on the finite element model of ankle joint and simulating the different working conditions of ALAS sprain,it is concluded that the back extension state of ankle joint can also lead to ALAS,and the injury of anterior talofibular ligament and calcaneal fibular ligament is closely related to varus and internal rotation moment.Different combinations of varus and internal rotation moments lead to the injury of the anterior talofibular ligament in the early stage of metatarsal flexion of the ankle joint.The varus moment is the main factor of the injury of the anterior talofibular ligament in the early stage of metatarsal flexion.Varus and internal rotation moment are the main factors affecting the occurrence of ALAS,while metatarsal flexion or dorsal extension are secondary factors. |
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