RESUMO
INTRODUCTION: After reconstruction of the anterior cruciate ligament, the modification processes in the transplanted tendon tissue directly influence the biomechanical properties of the knee. The histopathological alterations in failed grafts have hardly been studied. OBJECTIVE: Our study focused on examining the presence and extent of tendinosis (low or high grade) in the tendon tissue of failed anterior cruciate ligament reconstructions. We considered its relationship to the type of transplant, the symptoms, the arthroscopic appearance, the mode of trauma, and the timing of the failure. MATERIALS AND METHODS: The tendon tissue of failed anterior cruciate ligament reconstructions in 30 patients was gathered during revision surgery and its histopathology was analysed for the occurrence of structural alterations. The classification of the tendinosis as low or high grade was semiquantitative based on five qualities. We used a standardised questionnaire to collect patient data and we used the Marburg Arthroscopy Score for the intraoperative evaluation of the graft. RESULTS: We found histological vitality and, except for two samples, structural alterations consistent with tendinosis, predominantly high grade, in all failed anterior cruciate ligament grafts. No direct link could be proved between the degree of tendinosis and the type of graft used, the symptoms (except for instability) or the timing of the graft failure, the mode of trauma, or the arthroscopic appearance of the failed plasty. However, the accumulation of high-grade tendinosis in patients with hamstring tendons, subjective instability, and graft failure between 1 to 5 years postoperatively was noteworthy. CONCLUSION: Structural alterations consistent with tendinosis could be detected, with different expressions, in the vital tendon tissue of anterior cruciate ligament reconstructions. This indicates that the graft is subject to repetitive microtrauma. However, it is still unclear how tendinosis influences the failure of anterior cruciate ligament reconstructions.