ABSTRACT
PURPOSE: To evaluate the postoperative MR findings of the healthy anterior cruciate ligament (ACL) grafts which were confirmed by the second-look arthroscopic examination. MATERIALS AND METHODS: Among 419 cases who underwent the arthroscopic ACL reconstruction by one operator between June 1996 and January 2001, we evaluated 33 MR scans of 29 patients who underwent the postoperative MR scan and the second-look arthroscopic examination (4 patients underwent postoperative MRI twice). There were 18 male and 11 female patients, and the patient 's age ranges from 16 to 59 years-old (mean 29.7). There were 15 cases of autogeneous bone-patellar tendon-bone (BPTB) grafts, 13 cases of autogeneous double-loop hamstring grafts, and 1 case of allogeneous BPTB graft. Thirty-three MRIs were divided into 3 groups according to the time interval between operation and postoperative MR examination: less than 6 months, 7 to 12 months, and more than 13 months. The MR findings of ACL grafts - signal intensity, morphology, continuity, orientation, diameter - were analyzed. RESULTS: The increased signal intensity was found in 29 ACL grafts (87.7%) among 33 MR images. The most common pattern of the graft morphology was a longitudinal streak increased signal band (27 cases, 81.8%). The partial rupture was seen in 9 cases (27.3%), and the lax orientation in 4 cases (12.1%). According to Howell 's scoring system, the signal intensity score of the graft tended to decrease with time after operation, and the sagittal diameter of the graft tended to increase with time after operation. CONCLUSION: The main MR finding of the healthy ACL graft was longitudinal streak increased signal band. The graft signal intensity seemed to decrease, and the sagittal diameter of the graft seemed to increase, as time passes after operation.