OBJECTIVETo investigate the feasibility of utilizing self-designed score system for lower lumbar vertebral burst fractures to select surgical approach.

METHODSFrom January 2006 to December 2011, the clinical data of 56 patients with lower lumbar vertebra burst fractures who underwent surgical treatment were retrospectively analyzed. There were 42 males and 14 females with an average age of 43.1 years old (ranged, 19 to 65). Causes of injury included falling down (40 cases), traffic accidents (12 cases), and crashing injury by heavy objects(4 cases). Injury site was L3 in 37 cases, L4 in 16 cases, and L5 in 3 cases. According to the AO classification, 17 cases were type A3.1, 14 cases were type A3.2, 25 cases were type A3.3. According to Frankel grade of nerous function, 2 cases were grade B, 5 cases were grade C, 9 cases were grade D and 40 cases were grade E. Surgical methods and approaches were chosen based on the comprehensive evaluation of AO classification, condition of posterior column injury and spinal canal encroachment. Surgical methods and approaches included trans-vertebra fixation (15 cases), intra-vertebra pedicle screw fixation (21 cases), combination of anterior and posterior approaches (11 cases), one-stage posterior approaches (9 cases). Cobb angles, restorations of the affected vertebral anterior border height, and conditions of spinal canal encroachment were compared before and after surgery. Conditions of bone graft fusion and internal fixation (if bending, loosening or breakage existed) were observed. Spinal cord functions were assessed according to Frankel grade. Localized pain and working status of patients were also assessed at the last follow-up.

RESULTSNo incision infection was found and no spinal nerve symptoms improved in all of 56 patients. All patients were followed up for 12 to 60 months with a mean of 28.5 months, without internal fixation loosening or breakage. There was significant differences in Cobb angle, vertebral anterior border height and recovery of spinal canal encroachment between preoperative and postoperative instantly (P < 0.05), however, there was no significant difference between postoperative instantly and final follow-up (P > 0.05). Thirteen cases obtained fusion by trans-vertebra fixation, 20 cases obtained fusion by intra-vertebra fixation, and 20 cases were treated by the combination of anterior and posterior approaches or one-stage posterior approaches all of patients obtained fusion. Spinal nervous function recovered I to II grade, 1 case was grade C, 3 cases were grade D, 52 cases were grade E. Localized pain was assessed as P1 in 52 cases, P2 in 3 cases, and P3 in 1 case. Working status was classified into W1 in 12 cases, W2 in 39 cases, and W3 in 5 cases.

CONCLUSIONThe lower lumbar vertebra and thoracolumbar junction exhibit different injury characteristics due to variations in anatomy and biomechanics. A comprehensive score of the AO classification, posterior column injury and degree of spinal canal encroachment will guide the selection of surgical method and approach for the treatment of lower lumbar vertebra burst fractures.