Delayed cyclops syndrome: symptomatic extension block four years after anterior cruciate ligament reconstruction.

Loss of knee extension after reconstruction of the anterior cruciate ligament may occur due to a neoproliferative fibrous nodule located anterolateral to the tibial tunnel, termed cyclops syndrome. This nodule occurs usually within the early postoperative period and results in diminished knee extension due to impingement on the intercondylar notch. We report a case of a 24-year-old female patient with an uncommon delayed-onset loss of knee extension due to a cyclops syndrome four years after anterior cruciate ligament reconstruction.