Post-tibial cyst formation over 2 years after posterior cruciate ligament reconstruction

We report a case of an asymptomatic post-tibial cyst with direct communication to the posterior orifice of the tibial tunnel after a posterior cruciate ligament (PCL) reconstruction. Two years earlier, the patient had undergone a PCL reconstruction using a transtibial technique through a lateral tibial tunnel and with a 10-mm bio-absorbable interference screw fixation. Magnetic resonance imaging (MRI) was taken with patient's consent when the patient re-visited our hospital to remove the metal post-tie screw. The patient was satisfied with the result and the cyst was an incidental finding. This complication appeared to be a consequence of direct communication between the joint and the post-tibial tunnel through the posterior orifice of the tibial tunnel because of the failed osteointegration of the graft. To our knowledge, this is the first report of cyst formation at the post-tibial tunnel after a PCL reconstruction.