This is a retrospective study of 173 cases of chronic laxity of the knee, surgically treated between May 1985 and December 1988 using the MacIntosh technique (quadriceps-plasty) reinforced with the Kennedy ligament augmentation device (LAD). It involved 171 operations, 113 men and 58 women aged between 15 and 49 years (average 26 years), the majority of whom were active in sports both at competition (51 cases) and at recreational level (119 cases). There were 101 lesions of the medial meniscus (58.4%) and 94 lesions of the lateral meniscus (54.4%); only 41 knees had no meniscal lesion (23.6%). The results at medium term (between 4 and 8 years follow-up) were based on 107 cases (61.8%). The tolerance of the reinforcement was excellent as there were no instances of either acute or chronic synovitis in this series. The anatomical results evaluated using the Lachmann test (maximum manual Lachmann) showed no differential in 24 cases (22.8%), a differential of between 0 and 2 mm in 54 cases (50.5%), of between 2 and 4 mm in 20 cases (19%) and of > 4 mm in 9 cases (8.7%). The functional results evaluated using the Arpège CLAS system showed 83% of results to be satisfactory (score > 23). The radiological results showed that 63 knees (58.9%) had no subclinical or clinical signs of medial or lateral femorotibial osteoarthritis. In total, with an average follow-up of > 5 years (4-8 years), it was found that the MacIntosh quadriceps-plasty reinforced with the Kennedy LAD was not accompanied by any iatrogenic disease.(ABSTRACT TRUNCATED AT 250 WORDS)