Pedicle screw versus hybrid construct instrumentation in adolescent idiopathic scoliosis: meta-analysis of thoracic kyphosis.

STUDY DESIGN A quantitative meta-analysis was conducted on publishing studies reporting results of spinal surgery in adolescent idiopathic scoliosis with instrumentation of pedicle screw or hybrid construct. OBJECTIVE The primary objective is to get overview of the power to restore thoracic kyphosis using 2 different instrumentations. SUMMARY OF BACKGROUND DATA During the past years, surgery has mainly focused on correcting the coronal curve, but nowadays, the aims of posterior fusion and instrumentation are to achieve a stable, well-balanced spine in the coronal as well as in the sagittal planes. METHODS A PubMed and EMBASE search was conducted using combinations of the key words "hybrid construct" or "pedicle screw" with "adolescent idiopathic scoliosis" up to October 2013. A hand search of reference lists of obtained articles was also performed. RESULTS A total of 24 studies were identified and included in this meta-analysis. Of this, 12 included pedicle screw group only, 5 included hybrid construct group only, and 7 included both groups. The total number of patients was 1615. Age ranged from 9 to 26 years, with a mean of 15. For pedicle screw group, we got standard mean difference (SMD) as 0.40 (95% confidence interval, 0.31-0.50); I= 91.4%. For hybrid construct group, we got SMD as 0.15 (95% confidence interval, 0.04-0.26). Both intervals of SMD lay in positive value side. Overall SMD was 0.30 (95% confidence interval, 0.23-0.37). The positive value of SMD means thoracic kyphosis improves after surgery, whereas negative value means kyphosis loss after surgery. CONCLUSION There is overall tendency for both instrumentations to restore thoracic kyphosis. Hybrid construct seems to be more powerful in restoring kyphosis than pedicle screw. Preoperative important factor was found to be reasonably distributed or balanced. For operative factor, rod stiffness, fashion of hybrid construct, in situ bending, and rod rotation maneuver could have influence on results of kyphosis in different ways. Loss of correction and limited restoration of loss may do exist after correction. LEVEL OF EVIDENCE 3.