This study aimed to investigate the possible consequences of soft tissue interposition of Endobutton on clinical outcomes and reoperation rates after anterior cruciate ligament reconstruction.
We measured the distance between the centre of the Endobutton and the lateral femoral cortex on the postoperative first day anteroposterior X-rays of the 156 knees that underwent anterior cruciate ligament reconstruction. Those with a distance less than 1 mm were regarded as Group 1 (118 patients), the ones between 1 mm and 2 mm were regarded as Group 2 (30 patients) and the ones more than 2 mm were regarded as Group 3 (8 patients). The movement of the Endobutton of more than 1 mm along the femoral tunnel axis on anteroposterior X-rays or its rotation by more than 5° on lateral X-rays during follow-up were considered migration. Clinical assessment scores (Lysholm, Tegner Activity Scale), clinical examination tests, and rates of Endobutton migration in the groups were analysed.
Eleven Endobuttons (9.3%) in Group 1, 26 Endobuttons (86.7%) in Group 2 and all of the 8 Endobuttons (100%) in Group 3 were observed to have migrated. Clinical results and examination tests showed no significant difference between Groups 1 and 2, whereas a significant difference was detected in Group 3 compared to Groups 1 and 2 (p < 0.05).
Soft tissue interposition is a major cause of Endobutton migration, and an interposition over 2 mm between the Endobutton and the lateral femoral cortex can negatively affect the outcomes after an anterior cruciate ligament surgery.

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