Objective To discuss the clinical significance of internal fixation through anterolaterel and posteromedial approaches in the treatment of closed sagittal Pilon fractures of Topliss classification and compare the effects of the two approaches.Methods The study involved 57 patients with closed sagittal Pilon fractures treated with open reduction and internal fixation from 2007 to 2010,including 29 patients treated through anterolateral approach (Group A) and 28 through posteromedial approach (Group B).All patients were with closed fractures,and all surgery time windows were 10-19 days.The two groups were compared in aspects of gender,age,type of fractures,soft tissue graduation,injury factors,condition of combined fibula fracture,surgery time window,operation time,intra-operative blood loss,ambulation time,infection and necrosis rate of skin and soft tissue,length of stay,ankle joint function recovery after internal fixation,and intra-operative X-ray reduction.Results All patients were followed up for 12-26 months (mean,20 months) except for one patient in the Group A,with total follow-up rate of 98％.The two groups showed no significant differences regarding the gender,age,type of fractures,soft tissue graduation,injury factors,condition of combined fibula fracture,surgery time window selection,operation time,intra-operative blood loss,and ambulation time (P ＞0.05).While,the infection and necrosis incidence of skin and soft tissue,and the hospital stay we re significantly lower and shorter in the Group A than that in the Group B (P ＜ 0.05 ).Two patients in the Group A were complicated with toe extensor tendon adhesion,which was released by removing the fixation.Fifteen patients had wound infection during hospitalization,including three patients in the Group A and 12 in the Group B,but they were all cured after treatments like dressing.Fifteen patients were treated with stage Ⅰ allogeneic bone graft and 11 with autologous iliac bone graft.All the patients obtained bone union.Conclusions Topliss classification of closed sagittal Pilon fractures has clear clinical significance in surgical plan selection and operative procedures.Both of the anterolateral and posteromedial approaches can achieve good effects in the treatment of closed sagittal Pilon fractures due to high energy injury.However,the anterolateral approach is relatively a better choice,for it brings in a lower incidence of infection and necrosis of skin and soft tissue and a shorter length of hospital stay.