Purpose: Surgical correction for AIS has evolved from all hooks to hybrids or all screw constructs. Limited literature exists reporting outcomes using PHDS for posterior spinal fusion (PSF). This is the largest series in evaluating results of PHDS technique.
Methods: A retrospective review of consecutive AIS patients undergoing PSF by a single surgeon between 2006 and 2015 was performed. All eligible patients met a minimum 2-year follow-up. Patient demographics and radiographical parameters (radiographic shoulder height (RSH), T1 tilt, clavicle angle) at baseline, 6-week and 2-year post-operation were recorded. The primary outcome was difference in RSH from baseline measurements evaluated using repeated measures one-way analysis of variance with Bonferroni correction.
Results: A total of 219 patients (mean age at surgery: 13.68 years; 82% female) were included. The mean follow-up was 41.2 months (range 24-108 months). The RSH was significantly improved from - 14.7 ± 10.38 mm to 8.0 ± 6.9 mm (P < 0.0001). Clavicle angle was improved from 2.13° to 1.31° (P < 0.0001). T1 tilt was improved from 5.6° to 2.2° (P < 0.0001). At last follow-up, 95.8% of patients were shoulder balanced. There was a significant improvement of Cobb angle with an average correction of the upper thoracic curve of 42% and main thoracic curve of 67%.
Conclusion: The PHDS demonstrates the potential for additional shoulder balance improvement. Extension of fusion to structural proximal thoracic spine is the key to success for shoulder balance. It remains to be seen whether these improvements will translate into improved clinical outcomes in the longer term.
Keywords: Adolescent idiopathic scoliosis; Hybrid construct; PHDS technique; Pedicle screw construct; Shoulder balance.