The effect of lengthening of the percutaneous implant in the surgical treatment of Th-L ankylosed spine fractures: 4 segment fixation versus 5 to 8 segment fixation.

Abstract

Background: Fractures of thoracolumbar spine in the field of ankylosing diseases such as ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) can by surgically treated with miniinvasive posterior transpedicular fixation. The exact length of implant is the subject of several studies. In our study, we retrospectively evaluated the treatment of B3 fractures of the ankylosed thoracolumbar spine with use a shorter versus longer implant, always with 8 screws.

Methods: A total of 46 patients were included in the study (36 men and 10 women). Sixteen patients had AS and 30 patients had DISH. Patients treated between 2018 and 2022 with minimally invasive dorsal transpedicular fixation using 8 transpedicular screws were included in this study. We compared two groups where the first consisted of patients operated on with fixation of a maximum of 4 segments and the second group of patients consisted of patients in whom longer stabilization was used, at least 5 to 8 segments, with skipping of some vertebra between screws. We compared the effect of fixation length on reduction and retention before surgery, after surgery, and after 6 and 12 months. We evaluated the effect of reduction and retention on the basis of differences in the measurement of the Cobb angle and the angle, which we called "vege", which was formed by dislocation of the fracture. Furthermore, we monitored demographic data, the length of surgery, the number of complications, the number of concomitant injuries, the presence of a neurological deficit, and the result was assessed by the AO Spine PROST questionnaire.

Results: In the entire group of 46 patients, the difference in the "vege" angle was significant (p<0.001). When comparing the reduction between the groups with short and longer fixation, the difference was not significant (p=0.829). The difference of the Cobb angle before and after the surgery in the comparison between the two groups did not show a statistically significant difference (p=0.434). Measurements of the Cobb angle bisegmentally after 6 and 12 months showed a progressive change in terms of kyphotization, which was smaller in the group with longer fixation, this difference was not statistically significant (p=0.709). Complete reduction was achieved in the group with short fixation vs 75% vs 63.3% with longer fixation (p-0.739). At the check-up after 6 months, all incomplete intraoperative reductions were spontaneously reduced.

Conclusions: Based on this study, we could conclude that both used constructions are comparable in terms of treatment results. It can be observed that longer fixation is more resistant to kyphotization at 6 and 12 months, but we would need a larger group of patients to confirm this hypothesis. In all incomplete reduced fractures through the surgery, complete reduction after verticalization occurred within 6 months in both groups. The angle of reduction was greater in the group with longer fixation, but the difference was not significant (Tab. 6, Fig. 8, Ref. 31).