MRI of patellar tendon anterior cruciate ligament autografts

Twenty-one MR examinations were performed in 15 patients with clinically stable knees after arthroscopic anterior cruciate ligament (ACL) reconstruction with patellar bone-tendon-tibial bone autografts. The postoperative interval ranged from 3 months to 3 years 3 months (average 9.5 months). Proton- and T2-weighted sagittal images with axial and oblique sagittal T1-weighted images were obtained. The MR appearance of the autografts was categorized depending on distribution of dark signal band into type 1 (continuous, two patients), type 2 (proximal half, eight patients), type 3 (distal half, two patients), and type 4 (nonvisualization, three patients). There was no change in appearance of the grafts in those who had a second imaging within 1 year postoperatively. We conclude that the normal ACL autograft has a variable appearance and that criteria used in evaluating the native ligament is inadequate to assess the autografts.