Objective To compared effect of one-stage anterior-posterior combined decompression and fixation and one-stage posterior decompression and fixation for treatment of severe lumbar burst fractures.Methods The study reviewed severe lumbar burst fractures treated by onestage anterior-posterior combined compression and fixation (combined group,n =23) and one-stage posterior fixation and compression (posterior group,n =21) from January 2005 to Ju ne 2010.There were 35 males and 9 females with age ranging from 19 to 57 years (mean 36.6 years).Fracture involved L1 in 13 cases,L2 in 21,L3 in seven,L4 in three.All fractures were AO type A3.3.Load sharing scoring system(LSS) of the fracture ranged from 7 to 9 points (average 8.2 points).According to Frankel criterion,spinal cord function was classified as scale A in four cases,scaleB in nine,scale C in 17,scale D in 11,and scale E in three.Of the two groups,operation time,intraoperative blood loss,postoperative drainage volume,intra-and post-operative allogeneic blood transfusion volume were compared; Cobb' s angle,restoration of anterior height of injured vertebra,and improvement of vertebral canal stenosis before and after operation and at the final follow-up were estimated according to radiographic observation; interbody fusion and spinal cord function were observed in follow-up; local pain and work status were compared using Denis score.Results Posterior group were superior to combined group in aspects of operation time,intraoperative blood loss,postoperative drainage volume,and postoperative allogeneic blood transfusion volume (P < 0.05).Both groups were followed up for 12 to 48 months (average 29.5 months),without the presence of implant loosening or breakage.There were no significant differences between the two groups concerning correction of Cobb' s angle,restoration of anterior height of injured vertebra,and improvement of vertebral canal stenosis after operation as well as restoration of anterior height of injured vertebra and improvement of spinal canal stenosis at final follow-up.Whereas,some cases in posterior group had slight loss of correction angle after the removal of pedicle screws.All cases in both groups obtained satisfactory interbody fusion and their neurologic function had considerable recovery except for the cases of scale A nenrofunction.At final follow-up,Denis local pain score was better in posterior group than in combined group,but there were no significant difference of work status between the two groups,Conclusions Compared to the combined approaches,posterior approach gains advantages of small trauma,less bleeding,and short operation time in treatment of severe lumbar burst fracture,but the surgical indications need to be grasped strictly. Key words: Spinal injuries; Lumbar vertebrae; Fracture fixation,internal; Spinal canal decompression