[Decompression by mini-open posterior approach assisted with microscope for thoracolumbar burst fracture with severe spinal canal stenosis].

ABSTRACT

Objective: To investigate the effectiveness of posterior microscopic mini-open technique (MOT) decompression in patients with severe spinal canal stenosis resulting from thoracolumbar burst fractures. Methods: The clinical data of 28 patients with severe spinal canal stenosis caused by thoracolumbar burst fractures, who were treated by posterior microscopic MOT, which performed unilateral or bilateral laminectomy, poking reduction, intervertebral bone graft via spinal canal, and percutaneous pedicle screw fixation between January 2014 and January 2016 were retrospectively analyzed. There were 21 males and 7 females with a mean age of 42.1 years (range, 16-61 years). The involved segments included T 11 in 1 case, T 12 in 4 cases, L 1 in 14 cases, and L 2 in 9 cases. According to AO classification, there were 19 cases of type A3, 9 of type A4. According to American Spinal Injury Association (ASIA) grading, 12 cases were grade C, 13 grade D, and 3 grade E. The time between injury and operation was 3-7 days (mean, 3.6 days). To evaluate effectiveness, the changes in the visual analogue scale (VAS), percentage of anterior height of injured vertebrae, Cobb angle, rate of spinal compromise (RSC), and ASIA grading were analyzed. Results: All patients were performed procedures successfully. The operation time was 135-323 minutes (mean, 216.4 minutes). The intraoperative blood loss was 80-800 mL (mean, 197.7 mL). The hospitalization time was 10-25 days (mean, 12.5 days). The incisions healed primarily, without wound infection, cerebrospinal fluid leakage, or other early complications. All the 28 patients were followed up 12-24 months (mean, 16.5 months). No breakage or loosening of internal fixation occurred. All fractures healed, and the healing time was 3-12 months (mean, 6.5 months). Compared with preoperative ones, the percentage of anterior height of injured vertebrae, Cobb angle, and RSC at immediate after operation and at last follow-up and the VAS scores at 1 day after operation and at last-follow were significantly improved ( P<0.05). There was no significant difference in the percentage of anterior height of injured vertebrae and Cobb angle between at immediate after operation and at last follow-up ( P>0.05). But the RSC at immediate after operation and VSA score at 1 day after operation were significantly improved when compared with those at last follow-up ( P<0.05). The ASIA grading at last follow-up was 1 case of grade C, 14 grade D, and 13 grade E, which was significantly improved when compared with preoperative ones ( Z=3.860, P=0.000). Conclusion: MOT is an effective and minimal invasive treatment for thoracolumbar AO type A3 and A4 burst fractures with severe spinal canal stenosis, and it is beneficial to early rehabilitation for patients.