Direct Vertebral Rotation Versus Single Concave Rod Rotation: Low-dose Intraoperative Computed Tomography Evaluation of Spine Derotation in Adolescent Idiopathic Scoliosis Surgery.

STUDY DESIGN A comparative clinical study of two main corrective manoeuvres in scoliosis surgery. OBJECTIVE To compare the effectiveness of two main corrective manoeuvres: single concave rod rotation (SCRR) and direct vertebral rotation (DVR) in regard to apical vertebral rotation (AVR) and rib hump correction in adolescent idiopathic scoliosis (AIS) surgery. SUMMARY OF BACKGROUND DATA It remains unclear whether SCRR manoeuvre alone causes apical vertebral derotation (AVD) and rib hump correction. Although the influence of DVR on AVD and rib hump change has been described, it has been evaluated mainly with indirect methods. This is the first study to evaluate separately the derotational effectiveness of these two manoeuvres during the low-dose intraoperative computed tomography (ICT). METHODS A study group consisted of 38 AIS patients treated by posterior scoliosis surgery (PSS) with all pedicle screw constructs. All examined patients had dow-dose ICT evaluation (before correction, after SCRR, and after DVR). RESULTS We found SCRR ineffective - mean postcorrectional AVR increased insignificantly 1.5° (16.1% worsening) P = 0.170. On the contrary, an average postcorrectional AVR after DVR decreased significantly mean 3.1° (33.3% improvement) P = 0.049. Precorrectional rib hump angle was 19.3°, after SCRR 15°, and after DVR 12.3°. It was found that despite the lack of true derotation after SCRR there was a significant 22.3% decrease of the rib hump P = 0.043. Although the rib hump decreased significantly 36.3% after DVR as well P = 0.023. There was also significant difference between a rib hump angle after SCRR and DVR (P = 0.049). CONCLUSION SCRR does not lead to AVD. The true spinal derotation is possible only when DVR systems are used. The decrease of rib hump is achieved after both SCRR and DVR, but the improvement is significantly better after DVR. LEVEL OF EVIDENCE 3.