This paper reports the clinical outcome of the arthroscopic reduction and pull-out suture technique in acute and chronic displaced tibial spine anterior cruciate ligament (ACL) avulsion fractures. Between April 1997 and December 2000, 14 patients received an arthroscopic reduction and pull-out suturing of displaced tibial spine fractures (ACL avulsion fractures of tibia). Of 14 cases, ten were acute fractures and four were chronic nonunion fractures, in which all patients showed extension limitation. The mean follow-up period was 51 months (ranging from 30 to 80 months). At final follow-up, review of range of motion, Lachman test, anterior drawer test, KT-2000 arthrometer, Lysholm knee score, and Hospital for Special Surgery (HSS) score were evaluated. Compared to conventional pull-out suturing, several key modifications to surgical techniques were used. In all 14 patients, radiological bony union was detected at mean 12.3 weeks (range, 8–16 weeks) after surgery. All patients were able to return to their preinjury activity and sports level. At final follow-up, full range of motion was achieved in all patients. Anterior draw test, Lachman test, and KT-2000 (less than 3 mm side-to-side) were all negative in 13 patients. One female patient, who was 6 years old at the time of surgery, complained of no subjective instability, but showed Lachman grade I, and 5 mm side-to-side difference in KT-2000. She also revealed 10°̇ difference of genu recurvatum deformity. Two children (including the previously-mentioned 6-year-old female patient) showed leg-length discrepancy of 1 cm—the affected legs being longer—at final follow-up. The mean Lysholm knee scores were 95.6 (range, 92–100) and HSS knee scores were 96.4 (range, 91–100). Arthroscopic reduction with modified pull-out suturing technique in displaced tibial spine ACL avulsion fractures showed excellent union rate for both acute and chronic cases, without instability or extension limitations at minimum two-year follow-up.