Anterior Cruciate Ligament Reconstruction Grafts: MR Imaging Features at Long-term Follow-up—Correlation with Functional and Clinical Evaluation

PURPOSE: To assess the presence of increased intrasubstance signal intensity within anterior cruciate ligament (ACL) grafts and to assess whether such signal intensity changes are correlated to clinical assessments of graft instability and patient function 4-12 years after ACL reconstruction. MATERIALS AND METHODS: Ethical permission and written informed patient consent were obtained. The study was HIPAA compliant. Forty-seven patients were included and underwent 1.5-T magnetic resonance (MR) imaging of the knee that was treated surgically. Signal intensity characteristics of the ACL graft were evaluated on sagittal intermediate-weighted and sagittal and axial T2-weighted fast spin-echo MR images. The amount of signal intensity change, femoral and tibial graft tunnel position, and orientation of ACL graft in the coronal plane were assessed. Objective index of graft stability or laxity was performed with arthrometric testing, and subjective function was assessed by using International Knee Documentation Committee (IKDC) scoring. RESULTS: Increased intrasubstance graft signal intensity was found in 70 % (33 of 47) and in 64% (30 of 47) of patients on intermediate-weighted MR images and T2-weighted MR images, respectively. When present, intrasubstance graft signal intensity changes involved less than 25% of the maximal cross-sectional area of the graft in 70% (23 of 33) of cases on intermediate-weighted acquisitions and in 70% (21 of 30) of cases on T2-weighted acquisitions. No significant association was seen between graft signal intensity changes on intermediate-weighted and T2-weighted images and IKDC score (P = .667 and .698, respectively), arthrometric testing (P = .045-.99), and time since surgery (P = .592 and .610, respectively). CONCLUSION: Small amounts of increased intrasubstance graft signal intensity on intermediate- and T2-weighted images can be seen after ACL reconstruction at long-term follow-up of 4 years or longer and do not necessarily correlate with findings of joint instability or functional limitations in patients after ACL repair.