A ligament advanced reinforcement system (LARS) artificial ligament has been proposed for use in anterior cruciate ligament reconstruction in some cases, and an emerging body of reports has shown its success in the short term. However, there are great concerns about the potential risks of complications, which might prevent its extensive use. We report a rare case of serious synovitis 3 years postoperatively in a 26-year-old man who underwent LARS artificial ligament reconstruction. During revision arthroscopy, we observed a large amount of synovial hyperplasia in the knee joint, containing a large amount of hemosiderin deposition. In addition, the femoral tunnel was placed too anteriorly, and the ligament was ruptured near the tibial tunnel. Histologically, there was thick fibrous scar tissue around the graft, and poorly organized fibrous scar tissue infiltrated into the graft fibers, which could cause loss of structural integrity of the ligament and eventual graft failure. Collectively, our findings might arouse further in-depth research on the development of artificial ligament.