Cyclops and cyclopoid formation after anterior cruciate ligament reconstruction: clinical and histomorphological differences

Prospectively, 119 patients were pursued clinically and by follow-up-arthro scopy for the occurrence of a '"cyclops syndrome" after ACL reconstruction with a patellar tendon autograft, augmented by LAD. Twenty-one patients sho wed nodular formations. Ten of these (group I) developed early clinical evi dence of a "cyclops syndrome" with a mean extension deficit of 19 degrees b efore follow-up-arthroscopy,on average 5.9 months after the index operation . The nodular formations found and excised during debridement had a hard co nsistency. Histomorphological undecalcified microtome section evaluation of six specimens revealed fibrocartilagineous tissue with active bane formati on in the center. The other Il patients showed no clinical symptoms (group 2). A similar but soft nodulous scar formation was detected at follow-up-ar throscopy, on average 9.5 months after the index operation. Histomorphologi cally these so-called "cyclopoid" formations were only built-up fibrocartil agineous islands surrounded by granulation tissue. Neither remnants of tend on graft fibers nor old bone particles were found in specimens of either gr oup. It can be concluded that both the hard cyclops and the soft "'cyclopoi d" are de novo scar formations.