2020 Volume 11 Issue 5 Pages 827-834
Introduction: A common complication after corrective surgery for adult spinal deformity (ASD) is PJK (proximal junctional kyphosis), that is supposed to be caused by multifactorial etiology. As a strategy for reducing the incidence of PJK after corrective surgery for ASD, we have been carrying out the following 4 points; (1) Inserting pedicle screw at thoracic level using the PPS (percutaneous pedicle screw) technique to preserve the posterior soft tissues such as the back muscle and ligaments, (2) Inserting longer pedicle screws in the caudal direction obliquely at the upper instrumental vertebra (UIV), (3) Making the bending direction of the proximal end of rod slightly kyphotic along the surface of thoracic spine, (4) Setting the target lordosis between PI-10 and PI to avoid overcorrection. In this study, we compared the incidence of PJK before and after introducing this strategy in corrective surgery for ASD.
Methods: A total of fifty-three ASD patients who underwent corrective surgery at a single institution from 2016 to 2017 and had minimum 2-year follow-up were included. In the corrective surgery for ASD, lateral lumbar interbody fusion followed by posterior thoraco-lumbar fixation with percutaneous pedicle-screw technique was performed. Posterior fixation with PPS technique was performed from the lower thoracic spine to the pelvis in all cases. Out of 53 ASD patients, 28 patients underwent corrective surgery before introducing the strategy (Group C) and the rests (25 patients) underwent this surgery after introducing the strategies (Group X). Radiological assessment, including various spinopelvic parameters and proximal junctional angle (PJA), and the incidence of PJK were evaluated. PJA was defined as the angle between the lower endplate of UIV and upper endplate of 2-supra adjacent vertebra and PJK was defined as post-operative PJA greater than 10°.
Results: There was no significant difference between the two groups in various spinopelvic parameters. The incidence of PJK (Group X/Group C) was 0%/25% at post-op 6 months, 8%/32% at post-op 12 months and 12%/32% at post-op 18 months, showing statistically significant lower incidence at any follow-up periods in Group X (p< 0.05). The reoperation rate was 0% in Group X and 17% in group C, indicating significant lower rate in Group X (p< 0.05).
Conclusions: The result of this study is suggesting that our strategy for reducing the incidence of PJK after corrective surgery for ASD would be effective.
