Apical vertebral derotation in the posterior treatment of adolescent idiopathic scoliosis: myth or reality?

Abstract

Introduction Direct apical vertebral rotation represents an important goal of posterior surgery for thoracic adolescent idiopathic scoliosis (AIS), so as to obtain a better cosmetic effect and to avoid posterior thoracoplasty. However, the real effectiveness in correction of vertebral rotation, using posterior only procedures, is still open to debate. The aim of the present study is to compare the correction of axial apical rotation obtained with direct rotation procedure versus simple concave rod rotation, in patients treated by posterior fusion for thoracic AIS using pedicle screw-only construct. Materials and methods A retrospective review was performed on a total of 62 consecutive patients (one single institution, three different surgeons) affected by AIS, who had undergone a posterior spinal fusion with pedicle screwonly instrumentation between January 2005 and April 2008 at the reference center. All cases presented a main thoracic curve (Lenke type 1 and 2). The angle of rotation (RAsag) of the apical vertebra was measured from the preoperative and last follow-up axial CT. According to the derotation procedure, two groups were identified: a direct vertebral rotation group (DR group; n = 32 patients) and a simple concave rod rotation group (No-DR group; n = 30 patients). There were no statistical differences between the two groups, in terms of age, Risser's sign, curve patterns, Cobb main thoracic (MT) curve magnitude and flexibility, extension of fusion, offset measurements on the coronal plane and sagittal preoperative contour. ResultsAll 62 patients were reviewed at an average follow-up of 3.7 years (range 2.5-4.2 years). The DR group compared to the No-DR group showed a significantly better final correction of apical vertebral rotation (DR 63.4 % vs. No-DR 14.8 %; p \ 0.05) and a greater final correction (61.3 vs. 52.4 %; p \ 0.05) with better maintenance of the initial correction (-1.7°vs. -1.9°; ns) of the main thoracic curve. Concerning the coronal balance, there was the same aforementioned trend of better results in the DR group, with less final apical MT vertebra translation (DR 2.2 cm vs. No-DR 4.1 cm), greater overall change (preop-final) of lower instrumented vertebra (LIV) coronal tilt (-14.9°vs. -11.1°; p \ 0.05); the final global coronal balance (C7-S1) resulted quite better in DR group, but without a significant difference. The T5-T12 kyphosis angle was quite similar in both group before surgery (DR 16.8°vs. No-DR 17.5°) and was little lower at final followup evaluation in direct vertebral rotation group (14.5°vs. 16.5°). The T10-L2 sagittal alignment angle was similar in each group before surgery , and at the latest follow-up averaged 5.3°versus 8.2°, respectively. Lumbar lordosis was similar in each group before surgery (DR -42°vs. No-DR -44.1°) and at the final follow-up evaluation (-45.9°vs. -43.2°). At the latest follow-up, SRS-30 and SF-36 findings were similar between the two groups. The complication rate was higher in the simple concave rod rotation group (13.3 vs. 9.3 %), r...

Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system

“…Surprisingly, the torsion index reduction reached 44 %, and the apical vertebral rotation correction averaged 48.3 %, approaching the rates reported in the literature obtained using direct vertebral rotation (DVR) (42.5-64 %) [35][36][37] while obviating potential risks associated with DVR [38]. The unexpectedly high apical vertebral rotational reduction observed in the present patients might be explained by the fact that the corrective maneuver was mediated simultaneously by both rods, preassembled using fixed transverse connectors (Fig.…”

The Impact of Direct Vertebral Rotation (DVR) on Radiographic Outcome in Surgical Correction of Idiopathic Scoliosis

“…Reported efficacy of vertebral derotation varies widely, yet direct vertebral rotation showed the significantly better reduction of apical rotation over other methods [5,8,[30][31][32]. In our series, axial rotation changed significantly by 31.8% in DVR group comparing to 8.6% in non-DVR.…”

“…Several authors reported similar results. Di Silvestre et al, Kadoury et al, Samandi et al presented 8-10% better correction in coronal plane caused by DVR application [5][6][7]. In Lee's and Suk's papers, the differences were even more significant in favor of DVR.…”

“…15°). Although this simulation was established to correct axial rotation completely (to 0°), the situation not existing in clinical practice, there are clinical reports from DiSilvestre [5] and Mladenov [11] supporting this view-they both observed lower kyphosis results in DVR group in comparison to standard rod rotation alone. On the other hand, there are contradictory observations from Hwang et al who reported the decrease in postoperative kyphosis in the whole series of patients but did not find any worsening of the sagittal profile in DVR group [27].…”

“…Direct vertebral rotation (DVR) was developed with the expectation to complement correction of twisted spine, to overcome complications in rib hump reduction associated with thoracoplasty, as well as to reduce fusion extension and optimize correction in coronal and sagittal planes [2,[5][6][7][8]. DVR maneuvers consist of derotation of apex vertebrae (levels of greatest rotation and translation due to spinal deformity) and correction of the axial spinal deformity.…”