Arthroscopic findings associated with roof impingement of an anterior cruciate ligament graft.

Nineteen patients with roof impingement of an anterior cruciate ligament graft had their grafts inspected during second-look arthroscopy. The diagnosis of roof impingement was suspected from the clinical findings of an effusion, extension deficit, recurrent instability, or anterior knee pain. The diagnosis was confirmed when a portion of the tibial tunnel was anterior to the tibial intersection of the slope of the intercondylar roof on a lateral roentgenogram of the fully extended knee. During second-look arthroscopy the impinged anterior cruciate ligament graft had one or more of the following features: fractured bundles, guillotined remnants at the tibial insertion, parallel fragmentation of an uninterrupted graft, fibrous nodule, or an extrusion of graft material at the outlet of the notch. We hypothesize that these changes in the integrity of the anterior cruciate ligament graft are caused by mechanical injury from roof impingement. CLINICAL RELEVANCE. One should suspect that a patient with an effusion, extension deficit, recurrent instability, or anterior knee pain after an anterior cruciate ligament reconstruction may have roof impingement. A lateral roentgenogram in full extension is diagnostic if the tibial tunnel is anterior to the intercondylar roof. The surgeon should be aware that impinged grafts can have a variety of arthroscopic appearances in addition to the previously reported fibrous nodule or Cyclops lesion.