Objective:To introduce a new treatment of the avulsion fracture of tibial insertion of ACL of adolescent under arthroscope and to assess its efficacy.Methods:16 cases of adolescent patients with avulsion fracture of tibial insertion of ACL were treated by using two-strand Ethicon suture fixation in "8"shape under arthroscope.Reduction of the avulsion fragment was observed after surgery;relaxation and mobility degree of knee

KT 2000 value and Lysholm score

and the influence of histology of teenage patients were calculated.Results:All cases were followed-up

and the fracture blocks were reduced or nearly reduced anatomically in all the cases.No fragment was missing at fracture healing.One case got Lachman test(+)

but his tibial insertion was healed.One case with poor compliance had 10 degrees of limited knee extension.On average

KT2000 value was 0.8mm(-1~3 mm)

P<0.01;Lysholm score was 95.2

and the main reason for the score was the anterior knee pain at standing position

which was found owing to"cyclops syndrome" in the next arthroscopy.In the X ray in the 6th

12th

and 18th month after the operation

there was no deformation of the tibial plateau

or the formation of osseous bridge in epiphyseal plate

and the height and width were the same on the epiphyseal plate of both sides.Conclusion:Suture fixation in "8" shape under arthroscope can be used to treat the adolescent patients with avulsion fracture of tibial insertion of ACL.The fixation is reliable;the activity and function of the knee is good after surgery

and has no effect on the epiphyseal plate’s growth.The tension of the ligament should be checked after reduction of the avulsion fragment during the surgery.The "cyclops syndrome" should be considered when the anterior knee pain occurs after surgery.