Study Of Mechanism And Evaluation Of Achilles Tendon Injury And Repair

BackgroundAchilles tendon injuries are common disorders, including Achillestendinopathy and rupture, which are common in athletes and sedentarypopulations. The pathogenesis is not clear. Neovascularization is mainpathological features of Achilles tendinopathy and a prerequisite for therepair of Achilles tendon rupture, providing the necessary nutritions.Neovascularization withdraw during the process of remodeling. In thisstudy, new technology of ultrasound was used to evaluate Achilles tendoninjury and repair, and then explore its pathogenesis.ObjectiveFirstly, we intend to investigate the correlation between theneovascularization and mechanical property of Achilles tendinopathy.Secondly, we intend to investigate the correlation between theneovascularity and pain. Thirdly, CEUS was used to evaluate thevascularity during the healing processing of Achilles tendon rupture.Fourthly, SWE was used to investigate the stiffness of repaired Achillestendon postoperativly.Methods1. Achilles tendinopathy of rabbits were induced by collagenase injection.At3day,7days and14days, CEUS was performed to investigate thevascularity of injured Achilles tendon. For HE staining, the vasculardensity (MVD) of Achilles tendon was determined. For immunehistologicalanalysis, expression of VEGF-A, HIF-1α, MMP-3, Collagen Ⅰ and Ⅲexpression were determined. The failure load and stiffness weredetermined by mechanical testing. 2. Achilles tendinopathy of rats were induced by collagenase injection.Gait analysis was used to observe the percentage of three-legged stand,the pressure and area of affected foot. For immunehistological analysis,expression of VEGF-A,substance P and calcitonin gene-relatedpeptide(CGRP) were determined.3. Achilles tendon ruptures of rabbits were repaired surgically. CEUS wasused to evaluate the vascularity of repaired Achilles tendon one week,four weeks and eight weeks postoperativly. Expression of VEGF-A, typeⅠ and Ⅲ collagen were determined by immunehistologicalanalysis.Failure load and stiffness of repaired Achilles tendon wasinvestigated by biomechanical testing.5. Patients with Achilles tendon rupture in our hospital were treatedsurgically.They were divided into two group, rehabilitation group andcontrol group. After12,24and48weeks postoperatvely,SWE was used toevaluated the stiffness of repaired achlles tendon and AmericanOrthopaedic Foot and Ankle Society scorces (AOFAS scores) was used toevaluated the its function.Results1. MVD was correlated inversely with VEGF-A expression.Area undertime-intensity curve was correlated positively MVD. Failure load wasnegative correlated with MVD、VEGF expression.2. Percentage of three-legged stand was positively correlated with VEGF-A,substance P,CGRP expression.3. Area under time-intensity curve was positively correlated withMVD,VEGF-A expression.Ultimate load was positively correlated withMVD,VEGF-A expression.4. SWE showed the change of elastic modulus of the repaired Achilles tendon.The elastic modulus was positively correlated with AOFAS score. Conclusion1. CEUS can show the neovascularity within affected tendon and may be aneffective tool to assess tendon degeneration.2. Neovascularity and its accompanying sensory nerves secreteingneuropeptides such as substance P and calcitonin gene-related peptides,may be associated with tendon pain.3. CEUS may be used to asses the vascularity of repaired Achilles tendonand may be used to evaluate the process of tendon remodeling.4. SWE can evaluate the elastic modulus of repaired Achilles tendonpost-operatively. The elastic modulus was correlated with the function.