Study On MR Characteristics Of Achilles Tendon And Paratendon Tissue Injury And Immediate Change After Running In Amateur Marathon Runners

Objective: To use MR to evaluate the injury of Achilles tendon and paratendon tissue in amateur marathon runners,and to explore the correlation between injury and gender,running age and landing pattern;to quantitatively analyze Achilles tendon and Kager’s fat pad(KFP)by MAGi C technology Acute changes before and after running for 30 minutes.Methods: A total of 21 amateur marathon runners(14 males and 7 females)were recruited.Before running and immediately after running for 30 minutes,bilateral ankle joint MR imaging was performed to observe the MR appearance of Achilles tendon and paratendon tissues.Scanning sequences include sagittal T1 WI sequence,axial,sagittal and coronal fs-PDWI sequence,sagittal PD-fs-Cube sequence,sagittal MAGi C sequence,T1 and T2 can be obtained by reconstruction after MAGi C sequence scanning,PD 3 kinds of maps.The infrared motion spectrum capture system STT CLINICAL 3DMA is used to capture the subject’s gait and clarify the subject’s landing mode.The MAGi C sequence started from the attachment point of the Achilles tendon,intercepted 6 cm of the Achilles tendon,and divided the Achilles tendon into three sub-regions from far to near,including the insertion segment,the middle segment,and the tendon segment of the Achilles tendon.The T1,T2,and PD values of the area and KFP were evaluated by ICC to evaluate the consistency of data among observers.Multiple response analysis was used to analyze the MR performance of the Achilles tendon and paratendon tissues,and the chi-square test was used to analyze the correlation between the MR manifestations of the Achilles tendon and paratendon tissues and gender,running age and landing mode.Paired sample T-test and paired sample non-parametric test were used to compare the T1、T2,and PD values of the Achilles tendon and each subregion before and after running for 30 minutes,and to analyze Acute changes of the Achilles tendon and KFP of amateur marathon runners before and after running for 30 minutes.Results: The injury of Achilles tendon and its paratendin included Achilles tendinopathy,retrocalcaneal bursitis,peritendinitis of Achilles,bone marrow edema of calcaneus and paratendinitis of Achilles.The incidence of Achilles tendonitis in amateur marathon runners was the highest(78%,32/42),and the incidence of Achilles tendonitis was the lowest(29.30%,12/42).Landing mode is an influencing factor of Achilles tendinopathy and retrocalcaneal bursitis in amateur marathon runners(P=0.049,P<0.05),and Achilles tendinopathy and retrocalcaneal bursitis in amateur marathon runners who did not land on the rear foot The incidence of bursitis was higher than that of hind foot landing(P <0.05).There was no significant difference in the T1、T2,and PD signals of the entire Achilles tendon and each sub-region before and after running for 30 minutes(P>0.05).The T2 and PD values of the Kager fat pad had statistically significant differences before and after running for 30 minutes(P<0.05),but there was no significant difference in T1 values(P >0.05).The T2 and PD values after running were higher than those before running.There was no significant difference in gender and age in Achilles tendon and paratendon injury(P >0.05).Conclusion: The incidence of para-Achilles tendonitis is the highest in Achilles tendon and para-tendon tissue injuries,which may be because the Kager fat pad,as a special elastic fat tissue,is repeatedly squeezed during marathon exercise for a long time,which can easily lead to para-Achilles tendonitis.Non-hindfoot landing pattern is a risk factor for insertional Achilles tendinopathy and retrocalcaneal bursitis,and gender and running age are probably irrelevant factors for Achilles tendon and paratendinous tissue injury.A correct understanding of the related factors of Achilles tendon and paratendon tissue injury will help guide amateur marathon runners in scientific training and competition.The internal structure of each section of the Achilles tendon in amateur marathon runners is relatively stable,and there will be no acute injury before and after running for 30 minutes.The adjacent Kager fat pad plays a role in buffering and shock absorption during running.