Between April 1976 and December 1983 we treated 578 cases of anterior capsuloligamentous laxity of the knee surgically (148 acute and 430 chronic). The chronic cases were treated by a variety of techniques; peripheral plastic repair (191 cases), reconstruction of the anterior cruciate ligament with semitendinosus (127 cases), and with semintendinosus and gracilis (112 cases). To achieve uniformity of classification in such a large number of cases it was necessary to simplify and consolidate the data relative to history, objective examination, operative findings and criteria of evaluation of the results. A personal computer was used to provide rapid processing.