Usefulness of Percutaneous Pedicle Screw Fixation for Treatment of Lower Lumbar Burst (A3-A4) Fractures: Comparative Study with Thoracolumbar Junction Fractures.

Background: Percutaneous pedicle screw fixation (PPSF) without fusion has been recently recommended in the treatment of thoracolumbar fracture to reduce the adverse effects associated with the conventional open approaches and to restore range of motion. However, those studies report on the thoracolumbar junction, and there is no report on lower lumbar fracture. Purpose: To assess effectiveness of PPSF without fusion for treating lower lumbar burst (A3 and A4) fractures. Methods: A retrospective analysis was made to evaluate consecutive 50 patients with AO type A3 and A4 thoracolumbar fracture underwent PPSF. Patients were divided into a thoracolumbar junction (TLJ) group (T11-L2) and lower lumbar (LL) group (L3-5). The following items were measured and compared between the two groups. Vertebral height and consolidation, retropulsed fragment, sagittal curve and fixation failure were assessed with certain interval regularly. Results: The average height at pre- and post-reduction were 56.2% (36.2-74.3), 95.3% (84.2-98.3) in TLJ group and 65.7% (45.7-86.2), 91% (73.1-100) in LL group. The average canal area occupancy rate at pre- and post-reduction were 46.1% (37.4%-67.5%), 38.1% (31.3%-40.8%) in TLJ group and 40.4% (15.0-65.7), 19.3% (9.4-26.6) in LL group. Consolidation was completed within 12 months after surgery in both groups. There was no significant difference between two groups in clinical and radiographic parameters except cobb angle loss. Conclusion: Patients with lower lumbar fracture can be effectively managed with PPSF without fusion. PPSF following the implant removal can restore the movement of the lower lumbar spine, which is essential for daily life.