Abstract
Introduction
We aimed to determine the midterm effect of pedicle screw instrumentation on sagittal plane alignment, compared with a hybrid alignment, in the treatment of thoracic adolescent idiopathic scoliosis (AIS).
Methods
88 consecutive patients with AIS with a Lenke type 1 curve treated between 1998 and 2003 were analysed. Thoracic hooks were used in 45 patients (group Hy) and thoracic screws alone in 43 patients (group TPS). Preoperative average age (Hy 15·3 years vs TPS 16 years), sex (38 female and seven male vs 37 female and six male), Risser sign (2·9 vs 2·9), main thoracic curve (64° vs 65·5°), and thoracic kyphosis (22·6° vs 21·4°) were similar in both groups. Pearson correlation coefficient and univariate ANOVA were used.
Results
At a mean follow-up of 7·3 years (range 5–10), the TPS group had a greater final main thoracic curve correction (Hy 46·4% vs TPS 58·4%; p<0·001), with inferior loss of initial correction (–11·1° vs TPS –1·3°; p<0·0005). Absolute final thoracic kyphosis was similar in both groups (31·4° vs 25·4°; r=0·002; p>0·05), with both groups showing an equally statistically significant amelioration of the sagittal contour (Hy 49·2%; p<0·001 vs TPS 43·4%; p<0·001) (difference between groups p>0·05). We recorded a significant correlation between absolute kyphosis correction (final preoperative) and percentage main thoracic curve initial correction loss in the Hy group (r=0·35, p<0·001). The SRS–30 assessment showed an improvement in self-image and satisfaction, with no significant differences between groups.
Conclusions
The previously reported loss of kyphosis after a pedicle screw instrumentation in AIS, when compared with hybrid or hook only implants, should be questioned. At a minimum 5 years of follow-up, sagittal contour in the thoracic spine was not less kyphotic when pedicle screws were compared with hybrid constructs. The higher the loss of initial correction of main thoracic curve, the greater the postoperative absolute kyphosis at T5–T12 level. The clinical relevance of such radiographic differences is still undetectable with present self-assessment methods.
