To compare the clinical and radiological results after surgical treatments of the avulsion fractures of ACL between children and adults.

40 cases (18 cases of children, 22 cases of adults), who underwent surgical treatments after avulsion fractures of the ACL and followed up more than one year, were enrolled. Fractures were classified by modified Meyers & McKeever criteria. Range of motion, LK score, Lachman test, Pivot-Shift test, quadriceps muscle atropy and Telos® stress arthrometer were compared.

The types of fracture in children were categorized into 8 cases of type II, 10 cases of type III, and 2, 15, 5 cases of type II, III, IV each in adult group. Mean LK score showed significant difference between 99.3 points in children and 89.5 points in adults (p<0.05). In addition, accompanied injuries and the high degree of fracture leaded low LK score. However, there was no significant difference in range of motion, Lachman test and Pivot-Shift test. Anterior laxity by Telos® device showed an average of 2.0 mm in children, 2.5 mm in adults (p>0.05).

Children group showed better treatment results of avulsion fracture of ACL. Higher incidence of type II fractures and less combined injuries considered to be factors for better results.