In this study, we surveyed a consecutive series of 500 patients who had undergone an open procedure for chronic anteromedial and/or anterolateral instabilities. Those patients who had an open arthrotomy were separated for analysis. All of the patients were examined before and during surgery. A knee sheet, based on the kind used at the Hughston Orthopaedic Clinic in Columbus, Georgia, was used to record all clinical findings. Chondromalacia of the articular surface of the femur was detected at surgery in 161 patients (32%). A statistical analysis showed that the variables directly influencing degenerative changes of the cartilage are: a previous surgery that did not sufficiently restore joint kinematics (chi square = 20.238, P less than 0.001) and a time lapse of more than 30 months between first trauma and surgery (chi square = 21.736; P = 0.001). A higher score on dynamic (jerk or pivot shift) and static (internal and external anterior drawer) tests, indicating instability, or a meniscal tear alone do not statistically correlate with chondromalacia, but together they influence degenerative changes of the cartilage.