Alpaslan ŞENKÖYLÜ, Mehmet ÇETİNKAYA, İsmail DALDAL, Ali EREN, Erdem AKTAŞ

The implant density does not change the correction rate of the main and the accompanying curves: A comparison between consecutive and intermittent pedicle screw constructs

Objective: The aim of this study was to evaluate the clinical outcomes and the coronal correction rate of the main and accompanying curves of adolescent idiopathic scoliosis (AIS) corrected with pedicle screws inserted consecutively or intermittently. Methods: The prospectively collected data of 60 patients (8 men and 52 women; mean age: 14.6±2.5 years) who underwent corrective surgery for AIS between January 2010 and December 2015 were reviewed retrospectively. Two groups were constituted according to the pedicle screw construct type: consecutive pedicle screw construct (CPSC) and intermittent pedicle screw construct (IPSC) groups. The preoperative, early postoperative, and 24-month follow-up radiographs and the Scoliosis Research Society-22 (SRS-22) scores were reevaluated. The Cobb angle of the main and accompanying curves, the correction rate, and the flexibility of the curves were calculated. Results: The mean preoperative Cobb angles were 57.03° and 57.46°, the mean postoperative Cobb angles were 14.93° and 14.4°, and the mean correction rates were 76.22% and 75.31% in IPSC and CPSC groups, respectively (p>0.05). The preoperative and postoperative accompanying curve magnitudes and correction rates were similar (p>0.05). These radiographic outcomes were also consistent with the SRS-22 scores. Conclusion: Both the pedicle screw constructs had satisfactory outcomes following the surgery, which were confirmed by both the SRS-22 scores and radiographs taken perioperatively and at follow-ups. The IPSC and CPSC groups did not demonstrate a significant change in the correction rate of the main and minor or major accompanying structural and nonstructural curves, and also in the SRS-22 scores.

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1. Helenius I, Remes V, Yrjonen T, et al. Harrington and Cotrel-Dubousset instrumentation in adolescent idiopathic scoliosis. Long-term functional and radiographic outcomes. J Bone Joint Surg Am 2003; 85: 2303-9. [Crossref]

2. Cotrel Y, Dubousset J. A new technic for segmental spinal osteosynthesis using the posterior approach. Orthop Traumatol Surg Res 2014; 100: 37-41. [Crossref]

3. Boucher HH. A method of spinal fusion. J Bone Joint Surg Br 1959; 41: 248-59. [Crossref]

4. Quan GM, Gibson MJ. Correction of main thoracic adolescent idiopathic scoliosis using pedicle screw instrumentation: does higher implant density improve correction? Spine (Phila Pa 1976) 2010; 35: 562-7. [Crossref]

5. Sariyilmaz K, Ozkunt O, Karademir G, Gemalmaz HC, Dikici F, Domanic U. Does pedicle screw density matter in Lenke type 5 adolescent idiopathic scoliosis? Medicine (Baltimore) 2018; 97: e9581. doi: 10.1097/MD.0000000000009581. [Crossref]

6. Wang X, Larson AN, Crandall DG, et al. Biomechanical effect of pedicle screw distribution in AIS instrumentation using a segmental translation technique: computer modeling and simulation. Scoliosis Spinal Disord 2017; 12: 13. doi: 10.1186/ s13013-017-0120-4. eCollection 2017. [Crossref]

7. Clements DH, Betz RR, Newton PO, Rohmiller M, Marks MC, Bastrom T. Correlation of scoliosis curve correction with the number and type of fixation anchors. Spine (Phila Pa 1976) 2009; 34: 2147-50. [Crossref]

8. Delikaris A, Wang X, Boyer L, Larson AN, Ledonio CGT, Aubin CE. Implant density at the apex is more important than overall implant density for 3D correction in thoracic adolescent idiopathic scoliosis using rod derotation and en bloc vertebral derotation technique. Spine (Phila Pa 1976) 2017; 43: 639-47. [Crossref]

9. Luo M, Wang W, Shen M, Luo X, Xia L. Does higher screw density improve radiographic and clinical outcomes in adolescent idiopathic scoliosis? A systematic review and pooled analysis. J Neurosurg Pediatr 2017; 19: 448-57. [Crossref]

10. Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am 2001; 83: 1169-81. [Crossref]

11. Alanay A, Cil A, Berk H, et al. Reliability and validity of adapted Turkish Version of Scoliosis Research Society-22 (SRS-22) questionnaire. Spine (Phila Pa 1976) 2005; 30: 2464-8. [Crossref]

12. Carreon LY, Sanders JO, Diab M, et al. The minimum clinically important difference in Scoliosis Research Society-22 appearance, activity, and pain domains after surgical correction of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2010; 35: 2079-83. [Crossref]

13. Bharucha NJ, Lonner BS, Auerbach JD, Kean KE, Trobisch PD. Low-density versus high-density thoracic pedicle screw constructs in adolescent idiopathic scoliosis: Do more screws lead to a better outcome? Spine J 2013; 13: 375-81. [Crossref]

14. Gebhart S, Alton TB, Bompadre V, Krengel WF. Do anchor density or pedicle screw density correlate with short-term outcome measures in adolescent idiopathic scoliosis surgery? Spine (Phila Pa 1976) 2014; 39: 104-10. [Crossref]

15. Larson AN, Polly DW Jr, Diamond B, et al. Does higher anchor density result in increased curve correction and improved clinical outcomes in adolescent idiopathic scoliosis? Spine (Phila Pa 1976) 2014; 39: 571-8. [Crossref]

16. Sanders JO, Diab M, Richards SB, et al. Fixation points within the main thoracic curve: does more instrumentation produce greater curve correction and improved results? Spine (Phila Pa 1976) 2011; 36: 1402-6. [Crossref]

17. Yang S, Jones-Quaidoo SM, Eager M, et al. Right adolescent idiopathic thoracic curve (Lenke 1 A and B): does cost of instrumentation and implant density improve radiographic and cosmetic parameters? Eur Spine J 2011; 20: 1039-47. [Crossref]

18. Chen J, Yang C, Ran B, et al. Correction of Lenke 5 adolescent idiopathic scoliosis using pedicle screw instrumentation: does implant density influence the correction? Spine (Phila Pa 1976) 2013; 38: 946-51. [Crossref]

19. Liu H, Li Z, Li S, et al. Main thoracic curve adolescent idiopathic scoliosis: association of higher rod stiffness and concave-side pedicle screw density with improvement in sagittal thoracic kyphosis restoration. J Neurosurg Spine 2015; 22: 259-66. [Crossref]

20. Ketenci IE, Yanik HS, Demiroz S, Ulusoy A, Erdem S. Three-Dimensional correction in patients with lenke 1 adolescent idiopathic scoliosis: comparison of consecutive versus interval pedicle screw instrumentation. Spine (Phila Pa 1976) 2016; 41: 134-8. [Crossref]

21. Larson AN, Aubin NAC-E, Polly DW Jr, et al. Are more screws better? A systematic review of anchor density and curve correction in adolescent idiopathic scoliosis. Spine Deform 2013; 1: 237-47. [Crossref]

22. Gotfryd AO, Avanzi O. Randomized clinical study on surgical techniques with different pedicle screw densities in the treatment of adolescent idiopathic scoliosis types lenke 1A and 1B. Spine Deform 2013; 1: 272-9. [Crossref]

23. Kemppainen JW, Morscher MA, Gothard MD, Adamczyk MJ, Ritzman TF. Evaluation of limited screw density pedicle screw constructs in posterior fusions for adolescent idiopathic scoliosis. Spine Deform 2016; 4: 33-9. [Crossref]

24. Rushton PR, Elmalky M, Tikoo A, Basu S, Cole AA, Grevitt MP. The effect of metal density in thoracic adolescent idiopathic scoliosis. Eur Spine J 2016; 25: 3324-30. [Crossref]

25. Li M, Shen Y, Fang X, et al. Coronal and sagittal plane correction in patients with Lenke 1 adolescent idiopathic scoliosis: A comparison of consecutive versus interval pedicle screw placement. J Spinal Disord Tech 2009; 22: 251-6. [Crossref]

26. Larson AN, Polly DW Jr, Ackerman SJ, et al. What would be the annual cost savings if fewer screws were used in adolescent idiopathic scoliosis treatment in the US? J Neurosurg Spine 2016; 24: 116-23. [Crossref]

27. Suk SI, Lee SM, Chung ER, Kim JH, Kim SS. Selective thoracic fusion with segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis: More than 5-year follow-up. Spine (Phila Pa 1976) 2005; 30: 1602-9. [Crossref]