| Objective:To observe the MR morphology and signal characteristics of patellar tendon（PT）in amateur marathon runners to explore the influence of long-term marathon exercise on the morphological characteristics of PT.Dynamically observe the morphological characteristics of PT before and after a half-marathon to explore the short-term effect of a half-marathon running on the morphological characteristics of PT.Methods:19 male amateur marathon runners of 38 knee joints were enrolled to receive 1.5T MRI scan before the half-marathon,within 3 hours after running,3 days after running,and 1 week after running.10 healthy male volunteers of 20 knee joints were recruited as controls.MR scanning sequences include sagittal T1WI,sagittal and coronal fs-PDWI and 3D-fast imaging with steady-state precession T2WI（3D-FISP-T2WI）sequences.Firstly,the morphology and signal of PT in the runners group and the controls were qualitatively diagnosed and compared on the routine sequence,and then the MR morphology and signal changes of PT in the runners group were evaluated 4times before and after running.Three morphological parameters length,proximal,middle and distal cross-sectional area（CSA）,and volume of PT were measured using the post-processing tool ITK-SNAP,and the data were standardized.According to the occurrence of patellar tendinitis,the runners were divided into non-patellar tendinitis group and patellar tendinitis group,and the independent sample t-test or non-parametric test was used to make further comparison with the controls.The differences of PT CSA between proximal,middle and distal parts in each group were analyzed by single factor variance（ANOVA）.One-way Repeated Measures ANOVA was used to analyze the morphological changes of PT of amateur marathon runners before half-marathon running（t0）,3h after running（t1）,3 days after running（t2）and 1 week after running（t3）.The comparison of the mean of multiple groups of samples was conducted by LSD method.Results:There was no obvious abnormality in the morphology and signal of PT in controls.The incidence of asymptomatic patellar tendinitis in amateur marathon runners was 26.3%（10 sides/38 sides）.No significant MR signal changes of PT were observed in all runners during 3 follow-up visits after running.In the amateur marathon runners’group,the PT length was 45.48±0.45 mm,the proximal,middle and distal CSA were103.00（92.54,132.79）mm2,99.16±16.71 mm2,104.89±17.39 mm2,respectively,and the volume was 3970.11±558.69 mm3.In controls,the PT length was 46.37±0.28 mm,the proximal,middle and distal CSA were 84.58±14.44 mm2,91.27±12.06 mm2,92.96±12.71 mm2,respectively,and the volume was 3628.75±455.96 mm3.To evaluate the effect of patellar tendinitis on the morphology of PT,the runners were divided into the non-patellar tendinitis group（14 cases/28 sides）and patellar tendinitis group（5 cases/10 sides）for further comparison according to the occurrence of patellar tendinitis.In the non-patellar tendinitis group,the PT length was 46.83±3.35 mm,the proximal,middle and distal CSA were 98.98±13.14 mm2,92.92±10.92 mm2,100.27±14.37 mm2,respectively,and the volume was 3826.57±499.23 mm3.In the patellar tendinitis group,the PT length was 43.40（39.35,45.33）mm,the proximal,middle and distal CSA were 147.88±14.65 mm2,116.65±18.12 mm2,117.82±19.28mm2,respectively,and the volume was 4372.00±540.36 mm3.After the data was standardized,the proximal CSA in non-patellar tendinitis group was larger than that in controls（P<0.05）,and there was no significant difference in length,medium and distal CSA and volume compared with controls（All P>0.05）.The PT length in patellar tendinitis group was shorter than that in controls（P<0.05）,and the proximal,middle and distal CSA and volume were larger than those in controls（All P<0.05）.Intra-group comparison:There was no significant difference in proximal,middle and distal CSA in non-patellar tendinitis group and the controls（All P>0.05）.The proximal CSA of the patellar tendinitis group was larger than that of the middle and distal CSA（P<0.05）,and there was no statistical difference between the middle and distal CSA（P>0.05）.Dynamic observation:In the non-patellar tendinitis group,the length,proximal and distal CSA and volume of PT increased at 3h after running（P<0.05）,and there was no significant difference between 3 days,1 week after running and before running.The middle CSA was not significantly different in different periods.In the patellar tendinitis group,the proximal,distal CSA and volume of PT increased at 3h after running（P<0.05）,and there was no significant difference between 3 days,1 week after running and before running.The length and middle CSA of PT were not significantly different in different periods.Conclusion:Long-term running has effect on the normal PT morphology in male amateur marathon runners,showing an increase in proximal CSA,while the length and volume of PT have no significant change.A half-marathon will not cause serious acute patellar tendon injury,but will affect the length,regional CSA and volume in asymptomatic male amateur marathon runners.However,these change ars reversible.Further studies are necessary to clarify the time interval of the patellar tendon morphological recovery,and to provide scientific guidance for marathon training and competition. |
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