Abstract Direct Vertebral Rotation (DVR): A New Technique of 3-D Deformity Correction with Segmental Pedicle Screw Fixation in Adolescent Idiopathic S

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1 Abstract Direct Vertebral Rotation (DVR): A New Technique of 3-D Deformity Correction with Segmental Pedicle Screw Fixation in Adolescent Idiopathic Scoliosis (AIS) Sang-Min Lee, MD, Se-Il Suk, MD, Ewy-Ryong Chung, MD Seoul Spine Institute, Inje University Sanggye Paik Hospital, Study Design: A prospective study Objectives: To introduce a new technique, direct vertebral rotation (DVR), and to compare the surgical results with those of a simple rod derotation (SRD) Summary of Background Data: Pedicle screw fixation, with a simple rod derotation maneuver, enables powerful coronal and sagittal plane corrections in scoliosis surgery However, the ability for rotational correction is still unclear Methods: Thirty-eight AIS patients, treated with segmental pedicle screw fixation, were analyzed The first group (n=17) was treated by DVR, and the second (n=21) by SRD Having similar preoperative curve patterns, both groups were evaluated for the deformity correction and spinal balance Results: In the DVR group, the average preoperative AVR of 167 was corrected to 96, showing a 425% correction, while in the SRD group, the correction was negligible, from 161 to 157 (24%) In the DVR group, the preoperative thoracic curve of 55 was corrected to 12 (796%), and the lumbar curve from 39 to 7 (805%) In the SRD group, the preoperative thoracic curve of 53 was corrected to 17 (689%), and the lumbar curve from 39 to 16 (622%) The average LIVT correction was 806 and 663% in the DVR and SRD group, respectively There were statistically significant differences in the coronal curve, LIVT and rotational correction (p<005, Mann-Whitney u test) Conclusions: The segmental pedicle screw fixation with direct vertebral rotation showed better rotational and coronal corrections than the simple rod derotation Key Words: Idiopathic scoliosis, Pedicle screw fixation, Rotational correction, Direct vertebral rotation (DVR) Address reprint requests to Sang-Min Lee, MD, Seoul Spine Institute, Inje University Sanggye Paik Hospital #761-1 Sanggye-dong, Nowon-gu, Seoul, , Korea Tel: , Fax: ,

2 , C-D, 3 1,5,6,7,8,11,14,16,19,20) 10,, (intra-vertebral) (inter-vertebral) (DVR, direct vertebral rotation) (stable vertebra), Harrington,, (flat back deformity),,, ( v e c t o r ) ( ) 1980, C-D /, 3,13,17,18) 3 90 Table 1 The results of surgical correction Group I (n=17) Group II (n=21) p value Thoracic Curves Preoperative >005 Postoperative* Correction 796% 689% Lumbar Curves Preoperative >005 Postoperative* Correction 805% 622% Thoracic Kyphosis Preoperative >005 Postoperative >005 LIVT Preoperative >005 Postoperative* Correction 806% 663% AVR Preoperative >005 Postoperative* Correction 425% 24% Decompensation Preoperative 4 / 17 5 / 21 Postoperative 2 / 17 2 / 21 AVR:apical vertebral rotation LIVT:lower instrumented vertebral tilt * Significant difference in Mann-Whitney u test

3 Fig 1 A Two forces induced by the rod derotation First, the vector of rod derotation is directed posteriorly and medially Second, the rod also rotated about 90 degrees on its own axis during the rod derotation This may affect the vertebral rotation in scoliosis Fig 1 B a) In the severe or rigid scoliosis, there are high amounts of frictions between the pedicle screws and the rod The vertebral rotation will be aggravated during the rod derotation because the direction of vertebral rotation will be same to the direction of the rod rotational axis b) In the very flexible, mild curves, the screw would glide on the rod Rod derotation might have some effect on the vertebral rotation, depending on the angle between pedicle screws and vector of the rod derotation Fig 1 C Diagram of direct vertebral rotation (DVR) During or after rod derotation (a-c), rotate the screw derotators to the opposite direction (d-f)

4 ( ), (Fig 1C) (Fig 1A) (severe scoliosis),,, ( 4 ~6 ) derotators,, 3, ( w i r e ),, (rod derotation),, (Fig 1B),,,, : Fig 2 A Simple rod derotation Derotate the pre-contoured rod on the correction sides (counter-clockwise rotation) Fig 2 B DVR Insert the screw derotators onto the pedicle screws both in concave and convex sides Rotate the screw derotators to the opposite direction (clockwise rotation of the rod derotation Fig 2 C Model picture of DVR

5 King 1 King 1 3, King 2 7, King 3 4, King 4 1 King 5 2, 2 King 1 5, King 2 8, King King 4 1 ( 1 ) 21 bias ( 2 ) Fig 3 A, B A 146 year-old AIS girl with 96 of right thoracic and 54 of left lumbar curves Fig 3 C, D The patient was operated by DVR and selective thoracic fusion without anterior release Two years follow up standing radiographs show that the thoracic curve was corrected to 23 and the lumbar curve was spontaneously corrected to 4 with balanced spine The rotation of lumbar curve was also improved postoperatively (arrows) Fig 3 E, F Preoperative and postoperative medical photos

6 Fig 4 A, B Preoperative apical vertebral rotation of 196 (RAsac) was improved to 104, showing 469% correction by DVR Fig 4 C, D In the surgical field, the angle between the vertical line and nut driver that was fixed onto the apical screw was 34 after simple rod derotation It was significantly decreased (25 ) after DVR The right thoracic hump also decreased after DVR (arrow) Fig 4 E The screw length checked by intraoperative antero-posterior radiographs was 22mm after simple rod derotation It was decreased (18mm) after DVR, which means the apical vertebral rotation was improved Fig 4 F Preoperative narrow disc spaces on the concave side of the curvature were spontaneously widened after DVR without any distraction or compression

7 1: 1:16, 147 ( : 122 ~ 191 ) 2: 1: 20, 146 ( : 111 ~ 173 ) 2 Cobb, (LIVT), (AVR), C T 6 in situ 7 cross-link (RAsac, ) 1 2 cm 1, ( : 40~ 96 ), ( : 2~62 ) Table 1, 24 8 ( : 13 ~ 42 ) 2, ( : 40~78 ), ( : 18~ 68 ), 23 7 ( : 12~40 ) 1, (RAsac) , , ( % 2 ) , , % Cobb,, (p=0001, Mann-Whitney u test) (p>005, Mann-Whitney u test) (neutral vertebra) (rigid rod; C- D 70 mm stainless) ) (Fig 2-B, C) 5 ( ) ( ) King, 1 King 1 830%, King 2 806%, King 3 777%, King 4 767%, King 5 759% 2 King 1 668%, King 2 641%, King 3 742%, King 4 804% King ( ) 5 7 4, 2~3 805% , % ( (p=0001, ), Mann-Whitney u test) King 1 (Fig 2A) derotators (4-8 ) 9 5, 7 5 4, 788% 2 33 d e r o t a t o r s ( ,

8 9 618% (p=0001, Mann-Whitney u test) , 3 5) 3 (p>005, Mann-Whitney u test) 3,4,13,17,18) -, Pollock 16) C-D 1 LIVT , 806% 2, Krismer 10) LIVT Lenke 12) %, Bridwell 2 ) ( L I V T ) (p=0025, Mann-Whitney u test) ( F E M ) G a r d n e r - M o r s e Stoke 5) 8 CT 1 (RAsac) % 18) CT (RAsac) 62 24% 9) (RAsac) (p=0000, Mann-Whitney u test) 2 (RAsac) 10, 11, 14, 19 ), ,, , 2, (Fig 3 A-F) 2 1 (thoracoplasty) (chest tube) 5, (end vertebra) 2,,

9 , (RAsac) 425% (Fig 4-A, B), 1999 nut driver (Fig 4- C, D), (Fig 4E), (Fig 4F), (inter-vertebral) 3,, derotators derotators, 3 90, Nash Moe 2 (, King 2, Lenke Ic ),,,, 1 ( ) 796%, 689% %, 2 622%, 2,, 1,,,,, (, King 3,4 ; Lenke Ia, Ib ),,, (50% ), (intra-verte

10 bral), preliminary report Spine, 22: , ) Gray JM, Smith BW, Ashley RK, et al: D e r o t a t i o n a l, analysis of Cotrel-Dubousset instrumentation in idiopathic, scoliosis Spine,16:S391-3, ) Kaneda K, Shono Y, Satoh S, et al: Anterior correction of thoracic scoliosis with Kaneda anterior spinal system A preliminary report Spine, 22: ,1997, (LIVT) 19) Kim WJ, Suk SI, Kwon CS, et al: Changes in vertebral rotation following segmental pedicle screw instrumenta - LIVT tion and rod derotation in idiopathic thoracic scoliosis:, Part I - CT evaluation J of Korean Orthop Assoc, 33: , 1998, 10) Krismer M, Bauer R, Sterzinger W: Scoliosis correction 2, by Cotrel-Dubousset instrumentation The effect of derota -, tion and three-dimensional correction Spine, 17:S263-9, ) Labelle H, Dansereau J, Bellefleur C, et al: P r e o p e r a -, tive three-dimensional correction of idiopathic scoliosis 3 with the Cotrel-Dubousset procedure Spine, 20:1406-9,, ) Lenke LG, Bridwell KH, Baldus C, et al: C o t r e l - Dubousset instrumentation for adolescent idiopathic scol - iosis J Bone Joint Surg Am, 74: , 1992 REFERENCES 11) Aaro S and Dahlborn M: Estimation of vertebral rota - tion and the spinal and rib cage deformity in scoliosis by computer tomography Spine, 6:460-7, ) Bridwell KH: Surgical treatment of adolescent idiopathic scoliosis: the basics and the controversies Spine, 19: , ) Cotrel Y, Dubousset J, Guillaumat M: New universal instrumentation in spinal surgery Clin Orthop, 227:10-23, ) Delorme S, Labelle H, Aubin CE, et al: I n t r a o p e r a t i v e comparison of two instrumentation techniques for the cor - rection of adolescent idiopathic scoliosis Rod rotation and translation Spine, 24:2011-7, ) Gardner-Morse M and Stokes IA: T h r e e - d i m e n s i o n a l simulations of the scoliosis derotation maneuver with Cotrel-Dubousset instrumentation J Biomech, 27:177-81, ) Ghanem IB, Hagnere F, Dubousset JF, et al: Intraoper - ative optoelectronic analysis of three-dimensional verte - bral displacement after Cotrel-Dubousset rod rotation A 13) Muschik M, Schlenzka D, Robinson PN, et al: D o r s a l instrumentation for idiopathic adolescent thoracic scolio - sis: rod rotation versus translation Eur Spine J, 8:93-9, ) Papin P, Labelle H, Delorme S, et al: Long-term threedimensional changes of the spine after posterior spinal instrumentation and fusion in adolescent idiopathic scolio - sis Eur Spine J, 8:16-21, ) Perdriolle R and Vidal J: Morphology of scoliosis: threedimensional evolution Orthopedics, 10:909-15, ) Pollock FE and Pollock FE Jr: Idiopathic scoliosis: cor - rection of lateral and rotational deformities using the Cotrel-Dubousset spinal instrumentation system South Med J, 83:161-5, ) Suk SI, Lee CK, Chung SS: Comparison of Zielke ven - tral derotation system and Cotrel-Dubousset instrumenta - tion in the treatment of idiopathic lumbar and thoracolum - bar scoliosis Spine, 19:419-29, ) Suk SI, Lee CK, Kim WJ, et al: Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis Spine, 20: , ) Turi M, Johnston CE 2nd, Richards BS: Anterior cor - rection of idiopathic scoliosis using TSRH instrumenta

11 tion Spine, 18:417-22, ) Wood KB, Olsewski JM, Schendel MJ, et al: Rotational changes of the vertebral pelvic axis after sublaminar instrumentation in adolescent idiopathic scoliosis Spine, 22:51-7, 1997 : 3 (DVR), (SRD) : 38, 2 17 ( 1 ), 21 ( 2 ), (LIVT, lower instrumented vertebral tilt) (AVR) CT : %, % %, % (AVR) % , 24% (LIVT) 806% 663%, (p<005, Mann-Whitney u test) : :,,, (DVR)