Correction of deformity from convexity in adolescent idiopathic scoliosis

Introduction

Background

Seventy percent of curves in adolescent idiopathic scoliosis (AIS) will progress at the time of diagnosis, with surgical management commonly decided for those greater than 45° in immature patients, and greater than 50° in those who have reached skeletal maturity (1).

Posterior instrumentation using the “free-hand pedicle screw insertion technique” (1) is currently the most commonly used technique, in order to perform greater forces at the time of deformity correction (2). Currently, 80% of surgeons carry out the instrumentation with the majority of screws in the concavity of the curve, thus correcting the deformity from that side (2), however, the anatomical configuration of the pedicle, being closer to the great vessels and the medullary canal on the concavity side (3-7), encourages easier insertion of pedicle screws on the convexity side. Furthermore, higher incidence of medial breaches in spinal deformities has been described in screws implanted on the concavity side (8).

Rationale and knowledge gap

The technique, initially described as the ‘convex pedicle screw technique’ (9), shows optimal results when compared to other surgical techniques, using low implant density constructs (10). Initial studies suggested that, although adequate coronal correction could be achieved by correction from the convexity, this technique induces thoracic hypokyphosis, significantly impacting the sagittal profile (11,12). This statement is currently under discussion (13), with no clear evidence in this regard. At present, there is no clear evidence regarding the biomechanical or clinical advantage of implanting more screws on the concave or convex side (14,15).

Objective

Our objective is to demonstrate that correction of AIS using the convex-sided technique provides favorable outcomes in terms of coronal and sagittal correction, with a minimal number of neurovascular complications. We present this article in accordance with the STROBE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-25-166/rc).

Methods

This is a retrospective observational pre-post study, of patients diagnosed of AIS, who underwent surgery at General University Hospital Gregorio Marañón, with a maximum age of 21 years. From January 2019 to December 2021, all cases of AIS operated in General University Hospital Gregorio Marañón were collected. At General University Hospital Gregorio Marañón, all patients with surgical criteria are managed using the convex-sided correction technique, regardless of the magnitude of the curve or other factors. Patients who had undergone previous spinal surgery, those without adequately assessable pre- or post-surgical standing full-length spinal radiograph or those who did not complete the minimum 2-year follow-up were excluded. After applying these criteria, 50 patients were included in the final analysis. The flowchart can be found in Figure 1.

Figure 1 Flowchart of the patients analysed in the study.

All curves were classified according to the Lenke classification for AIS by two surgeons with expertise in spine surgery.

Posterior instrumentation was used in all cases, mainly based on pedicle screws and proximal transverse hooks. All patients underwent intraoperative neurophysiological monitoring.

This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the ethics committee of General University Hospital Gregorio Marañón (No. ESCOLI1). The patients’ guardians or the patients themselves provided informed consent to participate in the study.

Data collection

A variety of variables were collected: sex, age, Risser, postoperative admission days, number of instrumented levels, implant density (defined by the number of pedicle screws divided by the number of fused levels), number of intraoperative neurophysiological events [defined as a 50–60% decrease in somatosensory evoked potentials (SSEPs), unilateral or bilateral, or a decrease in motor evoked potentials (MEPs) of >75%] pre- and postoperative haemoglobin, total blood loss (using Nadler’s equation), postoperative blood transfusion requirements and median operative time.

Regarding pre- and postoperative radiological variables: the coronal Cobb angle of the structural curves, vertebral rotation of the apex (according to Nash and Moe), global coronal balance (measured as the deviation in millimetres in posteroanterior projection from the plumb line of C7 to the central sagittal vertical line), global sagittal vertical axis (SVA), cervical lordosis, thoracic kyphosis [measured by taking the most visible cranial vertebra (usually T3 or T4) and the inferior endplate of T12], lumbar lordosis, ‘rib index’ (16) (the division of the distance in millimetres between the posterior border of the most prominent rib and the posterior margin of the corresponding vertebra, and the distance between the same posterior margin and the other rib of the same vertebra) and ‘pedicle screw ratio’ (number of pedicles by number of total implants) (17).

Surgical technique

All structural curves were included in the fusion. Cefazolin 30 mg/kg was administered 30 minutes before the incision (which was maintained every 8 hours until Redon type drainages removal) and amikacin 15 mg/kg as a single dose. Intraoperative antibiotic prophylaxis with cefazolin was repeated every 4 hours, or in cases of bleeding greater than 1,500 mL or intraoperative administration of >2 litres of crystalloid solutions or blood products (18). Surgery was performed with the patient in prone position, under general anaesthesia, by performing controlled hypotension, and ensuring normothermia with a warming blanket, and intraoperative neurophysiological monitoring by stimulation of each of the screws to assess proximity to radicular and spinal cord structures, as well as neurophysiological monitoring of long spinal cord tracts during correction maneuvers.

An isolated posterior approach was performed in all cases. After subperiosteal dissection of the posterior elements up to the transverse process, bilaterally, and performance of partial inferior facetectomies (Schwab type I), 5.5 mm diameter pedicle screws were inserted in the thoracic spine and 6.5 mm diameter in the lumbar spine, monoaxial at the apex and polyaxial at the ends, using the ‘free-hand technique’. In patients with structural thoracic curve, transverse hooks were used at the proximal end of the assembly. All pedicles on the convexity of the structural curves were instrumented, whenever possible; while on the concavity, only the ends of the curve were instrumented. After verification of the screw position by direct neurophysiological stimulation, a cobalt-chromium rod is contoured to an optimal profile, bringing the spine as close as possible to the rod on the convexity side, and rod de-rotation maneuvers are performed, in situ rod bending using coronal and sagittal bending clamps, direct vertebral derrotation (DVR) at the apex and compression-distraction maneuvers at the ends of the assembly both proximally and distally, to ensure proper shoulder balance or tilt of the lowest instrumented vertebrae (LIV). Subsequently, another cobalt-chrome neutralization rod is placed in the concavity without additional maneuvers. The arthrodesis is completed by decorticating the posterior elements, using autologous bone graft from the surgical site and demineralised bone matrix. Intraoperative fluoroscopy was used in cases of doubt regarding the position of a screw or in case of a neurophysiological event. In addition, in all cases, final intraoperative antero-posterior (AP) and lateral radiographs were taken before proceeding with wound closure.

Statistical analysis

IBM SPSS Statistics, Version 26 (IBM Corp., Armonk, NY, USA) was used. A P value of less than 0.05 was used to achieve significance. The paired-samples Student’s t-test was used for comparison of quantitative variables.

Results

In the study period, 112 patients diagnosed with AIS were operated in General University Hospital Gregorio Marañón. After applying the exclusion criteria, 50 patients were included in the final analysis. The distribution of the curves, according to Lenke, as well as the degree of skeletal maturity, according to Risser, are shown in Figures 2,3. Based on Nash and Moe’s vertebral rotation, 13 (25.5%) were classified as type 1, 30 (58.8%) as type 2 and 8 (15.7%) as type 3. Ninety-five per cent of the patients were female, with a mean age of 14.5±3.5 years. The median operative time was 251±50 minutes. The mean number of instrumented levels was 11.2±1.8. The mean postoperative length of stay was 6.3±0.4 days. Mean blood loss was 4.3±0.3 g/dL Hb. Mean total blood loss (according to Nadler’s formula) was 877.1±279.2 mL. Postoperative transfusions were required in 26 of 51 patients (50.9%). The mean implant density was 1.37±0.15. Our mean pedicle screw ratio was 0.84±0.05.

Figure 2 Distribution of curves according to Lenke classification.

Figure 3 Distribution of the patient sample, according to the Risser staging system.

Radiological variables

A reduction in the Cobb angle of the major curve was achieved, from 53.0°±12.6° to 18.9°±9.5°, representing a correction of 64.1% (P<0.001). For the minor curve, a correction was achieved from 33.3°±11.4° to 17.5°±9.5°, representing a correction of 47% (P<0.01). Coronal balance changed from 3.6±1.9 to 2.3±4.2 mm (P=0.59). There was an improvement in SVA from −14.7±40 to 6.1±28.9 mm (P=0.10). Cervical lordosis decreased, ranging from 7.1°±10.4° to 5.9°±8.1° (P=0.01). Thoracic kyphosis also remained stable, from 32.7°±10.8° to 31.6°±13.4° (P=0.65). Lumbar lordosis did not change significantly, from 50.8°±10.6° to 46.9°±14.7° (P=0.16). The rib index decreased from 2.2±0.9 to 1.8±0.6 (P=0.003), which implies a flattening of the thoracic hump (Figure 4).

Figure 4 Pre- and post-operative images of a patient diagnosed with AIS, in whom T3–L4 instrumentation was performed. The coloured lines correspond to the Cobb angles of the major and minor curves, and to the Cobb angles of the lumbar lordosis and thoracic kyphosis. AIS, adolescent idiopathic scoliosis.

Radiological controls were performed 6 months after surgery and subsequently every year during the study period (2 years), with no changes observed in the variables mentioned above. At 2 years, the mean Cobb angle of the main curve was 19.3°±7.9°; thoracic kyphosis was 29.9°±15.2°, the mean coronal balance was 2.6±4.6 mm; and the SVA was 6.6±26.8 mm.

Complications

There were no intraoperative complications, either medical or directly related to the surgical technique, except for a single intraoperative neurophysiological event. Two early surgical wound infections (3.9%) were reported, which were resolved by surgical irrigation and debridement, with no need for material removal.

There were no complications of implant failure, adjacent level syndrome (development of alterations due to overload on segments above or below a fused vertebral segment), proximal junctional kyphosis [sagittal Cobb angle between the upper instrumented vertebrae (UIV) and two supra-adjacent vertebrae >15°], or “adding-on” phenomenon (additional increase in the disc angle below the LIV exceeding 5° or an additional increase in the deviation of the next vertebra below the LIV from the central sacrail vertical line (CSVL) exceeding 5 mm) during the 2-year follow-up.

In only one of the 50 patients who underwent surgery, a single intraoperative neurophysiological event occurred in a 14-year-old female patient with a T3–L1 curve with disc apex at T8–T9. The T12 screw implanted on the concavity side caused a drop in motor potentials in the left lower limb, which recovered completely after removal of the screw, with no post-op clinical signs or symptoms.

Discussion

Currently, in paediatric scoliosis, the most commonly used surgical technique is instrumentation with pedicle screws, performing the correction from the concavity of the curve (2). Scoliotic deformity correction techniques from the convexity have historically been less used, although they are currently experiencing a rise in popularity, with an increase in published results (9,10,13,19-21).

Convexity side presents less risk of injury to large vessels (3,6), due to the position of the aorta, more lateral and posterior in the concavity, especially in the apex of the deformity and in right curves (2,7). It has also been described that the prone position brings the aorta closer to the pedicles at the level of the apex of the concavity (4). The placement of pedicle screws in the convexity involves a lower risk of injury to the spinal canal, which is in close relation to the pedicles of the concavity (5,8).

There are several facts regarding bone anatomy that facilitate instrumentation on the convexity side: first, pedicles on the concavity side are narrower and more corticalised in patients with AIS and the greater the curve (22-24). Second, the medial pedicle wall in a scoliotic spine is narrower than in a normal spine, reaching a minimum thickness at T7 and T8, at the level of the concavity of the main curve (25). Third, there is an inversely proportional relationship between vertebral rotation and the transverse diameter of the pedicle on the side of the concavity (26). Finally, greater pedicle dysplasia has been found in proximal thoracic vertebrae of the concavity (27).

At a minimum, a learning curve of more than 60 supervised screws is required, with the peri-apical concavity area being the most difficult (28). Although the approximate incidence using the “free-hand technique” in AIS is around 12% for lateral and 20% for medial wall (29); breaching the pedicle walls can be a dramatic complication if it occurs close to the great vessels, on the concavity side (6,30). It is therefore logical to facilitate the surgical technique by inserting screws in an anatomically more accessible location, reducing the possible risks, this is useful at a time when, despite the increasing number of publications in which navigated or robot-assisted surgery demonstrates greater precision than conventional techniques, but it is not available in all centers (31).

Biomechanically, it should be noted that the pedicles of the convexity allow greater translational and rotational forces to be applied (24,32). The distances between implants are greater, allowing better resistance to the force vectors resulting from corrective manoeuvres (21). Additionally, derotation maneuvers performed from the concave side carry a higher risk of spinal cord injury, as distraction on the concavity tends to ’stretch’ the spinal cord (20). A greater theoretical risk of pull-out and implant failure has also been described when the de-rotation is performed from concavity side (33).

In our study, we achieved 64.1% of correction of the greater curve in the coronal plane, similar to that found with other surgical techniques based on instrumentation with pedicle screws (52–77%) (30) and in accordance with published results using convexity correction techniques (47.2–72%) (13).

With regard to the sagittal plane, in our study, thoracic kyphosis remained stable. Although there are publications (12), which find that from concavity it is possible to correct thoracic hypokyphosis more effectively, subsequent studies show that this parameter tends not to vary (8,18), and even to increase (34). On the other hand, the relative length of the anterior column in rotated vertebrae, when correcting apical lordosis, may cause a residual hypokyphosis (35), so that the side from which the correction is made does not play such a relevant role in this aspect. Also, there are several references in previous literature (36,37) stating that the profile in lateral full-length radiograph is usually normocyphotic, in line with the results obtained in our study, although this data should be considered with caution, as it does not allow for an assessment of the true magnitude of a deformity that is three-dimensional.

We reported only one neurophysiological event, which is lower than previously published results [1.9% of true neurophysiological events in AIS (38) and 3% events requiring intervention in the Scoliosis Research Society database for the correction of all types of spinal deformity] (39), with 0.71–0.94% of neurological symptoms also reported after paediatric scoliosis correction surgery (40,41).

Currently, low-density constructs are considered to be those with an implant density of less than 1.0–1.4 (according to references), although there is still no consensus on this issue (42,43). Our implant density is 1.37, which can be classified within the low-density group, reducing costs, especially considering that the cost of treatment per patient with AIS has only increased in recent years, partly due to the use of high-density constructs (44).

Our series of 50 cases at the same center is the second largest published, compiling all types of curves according to the Lenke classification [the first corresponds to the description of the technique, according to Tsirikos (9)]. In our study, we analyzed the changes in sagittal parameters and overall coronal and sagittal balance after correction, and we also measured the rib index, a radiological method for verifying improvement in the dorsal hump in our patients.

Our study is not without limitations. Firstly, this is a retrospective study. Secondly, the relatively small sample size and the inclusion criteria of a minimum follow-up period of 2 years may have influenced both the low percentage of infection and the minimal percentage of neurophysiological complications. However, the purpose of the publication of our results is to demonstrate that correction from convexity is possible, with results similar to those from concavity, and to increase the evidence in this respect, which is currently limited and inconclusive. Finally, the study was conducted in a single centre (the surgical team is made up of four surgeons specialised in paediatric spinal surgery), which could affect its external validity.

At this stage, it would be desirable to carry out a study with a larger sample size, multicentre, in order to validate the results shown in our article. Subsequently, and although the limited sample size of a rare and heterogeneous pathology could make this difficult, it would be desirable to carry out a prospective randomised study comparing correction from convexity versus correction from concavity.

Conclusions

In our experience, convex-sided correction, with a higher implant density at the convexity of the curve, is a valid technique, achieving a Cobb angle correction for the major curve of 64.1%, with no associated thoracic hypocyphosis, being anatomically more favourable, and associated with a very low risk of neurovascular complications.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-25-166/rc

Data Sharing Statement: Available at https://jss.amegroups.com/article/view/10.21037/jss-25-166/dss

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-25-166/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-25-166/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the ethics committee of General University Hospital Gregorio Marañón (No. ESCOLI1). The patients’ guardians or the patients themselves provided informed consent to participate in the study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Lenke LG, Kuklo TR, Ondra S, et al. Rationale behind the current state-of-the-art treatment of scoliosis (in the pedicle screw era). Spine (Phila Pa 1976) 2008;33:1051-4. [Crossref] [PubMed]
2. Jain A, Ahuja K, Roberts SB, et al. Techniques of Deformity Correction in Adolescent Idiopathic Scoliosis-A Narrative Review of the Existing Literature. J Clin Med 2025;14:2396. [Crossref] [PubMed]
3. Liu J, Shen J, Zhang J, et al. The position of the aorta relative to the spine for pedicle screw placement in the correction of idiopathic scoliosis. J Spinal Disord Tech 2012;25:E103-7. [Crossref] [PubMed]
4. Qiu XS, Jiang H, Qian BP, et al. Influence of prone positioning on potential risk of aorta injury from pedicle screw misplacement in adolescent idiopathic scoliosis patients. J Spinal Disord Tech 2014;27:E162-7. [Crossref] [PubMed]
5. Miyazaki M, Ishihara T, Kanezaki S, et al. Relationship between vertebral morphology and the potential risk of spinal cord injury by pedicle screw in adolescent idiopathic scoliosis. Clin Neurol Neurosurg 2018;172:143-50. [Crossref] [PubMed]
6. Valič M, Žižek D, Špan M, et al. Malpositioned pedicle screw in spine deformity surgery endangering the aorta: report of two cases, review of literature, and proposed management algorithm. Spine Deform 2020;8:809-17. [Crossref] [PubMed]
7. Burger JA, Becker LA, Li Z, et al. The aortic-vertebral distance is more associated with axial plane deformities than coronal and sagittal deformities in idiopathic scoliosis patients of Lenke types I and II. Eur Spine J 2025;34:593-601. [Crossref] [PubMed]
8. Smorgick Y, Millgram MA, Anekstein Y, et al. Accuracy and safety of thoracic pedicle screw placement in spinal deformities. J Spinal Disord Tech 2005;18:522-6. [Crossref] [PubMed]
9. Tsirikos AI. Correction of Adolescent Idiopathic Scoliosis Using a Convex Pedicle Screw Technique: A Novel Technique for Deformity Correction. JBJS Essent Surg Tech 2019;9:e9. [Crossref] [PubMed]
10. Ferlic PW, Hauser L, Götzen M, et al. Correction of adolescent idiopathic scoliosis using a convex pedicle screw technique with low implant density. Bone Joint J 2021;103-B:536-41. [Crossref] [PubMed]
11. 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] [PubMed]
12. Sudo H, Abe Y, Kokabu T, et al. Correlation analysis between change in thoracic kyphosis and multilevel facetectomy and screw density in main thoracic adolescent idiopathic scoliosis surgery. Spine J 2016;16:1049-54. [Crossref] [PubMed]
13. De Salvatore S, Asunis E, Oggiano L, et al. Correction of adolescent idiopathic scoliosis using the convex rod de-rotation maneuver: a systematic review. Eur J Orthop Surg Traumatol 2025;35:319. [Crossref] [PubMed]
14. Le Navéaux F, Aubin CÉ, Larson AN, et al. Implant distribution in surgically instrumented Lenke 1 adolescent idiopathic scoliosis: does it affect curve correction? Spine (Phila Pa 1976) 2015;40:462-8. [Crossref] [PubMed]
15. Pillot C, Wang X, Mallinos A, et al. Biomechanical analysis of 3D correction and bone-screw forces as a function of rod insertion sequence and orientation relative to the sagittal plane in adolescent idiopathic scoliosis instrumentation. Clin Biomech (Bristol) 2025;128:106618. [Crossref] [PubMed]
16. Lertudomphonwanit T, Berry CA, Jain VV, et al. Does Implant Density Impact Three-Dimensional Deformity Correction in Adolescent Idiopathic Scoliosis with Lenke 1 and 2 Curves Treated by Posterior Spinal Fusion without Ponte Osteotomies? Asian Spine J 2022;16:375-85. [Crossref] [PubMed]
17. Skalak TJ, Gagnier J, Caird MS, et al. Higher pedicle screw density does not improve curve correction in Lenke 2 adolescent idiopathic scoliosis. J Orthop Surg Res 2021;16:276. [Crossref] [PubMed]
18. Bratzler DW, Dellinger EP, Olsen KM, et al. Clinical practice guidelines for antimicrobial prophylaxis in surgery. Am J Health Syst Pharm 2013;70:195-283. [Crossref] [PubMed]
19. Kaliya-Perumal AK, Yeh YC, Niu CC, et al. Is Convex Derotation Equally Effective as Concave Derotation for Achieving Adequate Correction of Selective Lenke's Type- 1 Scoliosis? Indian J Orthop 2018;52:363-8. [Crossref] [PubMed]
20. Zifang H, Hengwei F, Yaolong D, et al. Convex-Rod Derotation Maneuver on Lenke Type I Adolescent Idiopathic Scoliosis. Neurosurgery 2017;81:844-51. [Crossref] [PubMed]
21. Takahashi S, Terai H, Toyoda H, et al. Surgical Outcomes of a New Technique Using a Convex Rod Rotation Maneuver for Adolescent Idiopathic Scoliosis. Spine Surg Relat Res 2021;5:205-10. [Crossref] [PubMed]
22. Hu X, Siemionow KB, Lieberman IH. Thoracic and lumbar vertebrae morphology in Lenke type 1 female adolescent idiopathic scoliosis patients. Int J Spine Surg 2014;8:30. [Crossref] [PubMed]
23. Watanabe K, Lenke LG, Matsumoto M, et al. A novel pedicle channel classification describing osseous anatomy: how many thoracic scoliotic pedicles have cancellous channels? Spine (Phila Pa 1976) 2010;35:1836-42. [Crossref] [PubMed]
24. Sakti YM, Lanodiyu ZA, Ichsantyaridha M, et al. Pedicle morphometry analysis of main thoracic apex adolescent idiopathic scoliosis. BMC Surg 2023;23:34. [Crossref] [PubMed]
25. Chiu CK, Wang WJ, Lee YJ, et al. The widths of the medial and lateral pedicle walls in adolescent idiopathic scoliosis with major thoracic curves. Spine J 2024;24:1293-301. [Crossref] [PubMed]
26. Garg B, Bansal T, Mehta N, et al. Is the morphology of the apical pedicles influenced by apical rotation or the coronal curve magnitude in adolescent idiopathic scoliosis?: a radiographic assessment. Spine Deform 2024;12:341-8. [Crossref] [PubMed]
27. Viroli G, Ruffilli A, Barile F, et al. Pedicle Dysplasia in Proximal Thoracic Adolescent Idiopathic Scoliosis Curves: What are We Missing and What are its Possible Surgical Implications? An Observational Retrospective Study on 104 Patients. Global Spine J 2025;15:1200-11. [Crossref] [PubMed]
28. Gang C, Haibo L, Fancai L, et al. Learning curve of thoracic pedicle screw placement using the free-hand technique in scoliosis: how many screws needed for an apprentice? Eur Spine J 2012;21:1151-6. [Crossref] [PubMed]
29. Librianto D, Saleh I. Breach Rate Analysis of Pedicle Screw Instrumentation using Free-Hand Technique in the Surgical Correction of Adolescent Idiopathic Scoliosis. J Orthop Case Rep 2021;11:38-44. [Crossref] [PubMed]
30. Hicks JM, Singla A, Shen FH, et al. Complications of pedicle screw fixation in scoliosis surgery: a systematic review. Spine (Phila Pa 1976) 2010;35:E465-70. [Crossref] [PubMed]
31. Łajczak P, Ayesha A, Jabbar R, et al. Comparison of accuracy of pedicle screw placement for adolescent idiopathic scoliosis using freehand fluoroscopic, navigation, and robotic-assisted techniques - a systematic review and bayesian network meta-analysis. Neurosurg Rev 2025;48:257. [Crossref] [PubMed]
32. Wang X, Aubin CE, Schwend RM. Concave or convex rod translation first in adolescent idiopathic scoliosis instrumentation with differential rod contouring? Stud Health Technol Inform 2021;280:150-2.
33. Rohlmann A, Richter M, Zander T, et al. Effect of different surgical strategies on screw forces after correction of scoliosis with a VDS implant. Eur Spine J 2006;15:457-64. [Crossref] [PubMed]
34. Şentürk S, Avci İ, Paksoy K, et al. Selective Apical Convex Rod Derotation: A Fast and Secure Technique for the Correction of Adolescent Idiopathic Scoliosis-A Case Series of 38 Patients. Oper Neurosurg 2025;28:635-40. [Crossref] [PubMed]
35. Schlösser TP, Abelin-Genevois K, Homans J, et al. Comparison of different strategies on three-dimensional correction of AIS: which plane will suffer? Eur Spine J 2021;30:645-52. [Crossref] [PubMed]
36. Pizones J, Núñez-Medina A, Sánchez-Mariscal F, et al. Thoracic sagittal plane variations between patients with thoracic adolescent idiopathic scoliosis and healthy adolescents. Eur Spine J 2016;25:3095-103. [Crossref] [PubMed]
37. Pasha S, Baldwin K. Preoperative Sagittal Spinal Profile of Adolescent Idiopathic Scoliosis Lenke Types and Non-Scoliotic Adolescents: A Systematic Review and Meta-Analysis. Spine (Phila Pa 1976) 2019;44:134-42. [Crossref] [PubMed]
38. Chen BJ, Tanaka M, Nakagawa T, et al. Importance of Intraoperative Neuromonitoring for Corrective Surgery in Patients with Adolescent Idiopathic Scoliosis. J Clin Med 2025;14:7693. [Crossref] [PubMed]
39. Lau KKL, Kwan KYH, Cheung JPY. Sensitivity of intraoperative electrophysiological monitoring for scoliosis correction in identifying postoperative neurological deficits: a retrospective chart review of the Scoliosis Research Society morbidity and mortality database. BMC Musculoskelet Disord 2025;26:186. [Crossref] [PubMed]
40. Dede O, Ward WT, Bosch P, et al. Using the freehand pedicle screw placement technique in adolescent idiopathic scoliosis surgery: what is the incidence of neurological symptoms secondary to misplaced screws? Spine (Phila Pa 1976) 2014;39:286-90. [Crossref] [PubMed]
41. Roberts SB, Tsirikos AI. Paediatric Spinal Deformity Surgery: Complications and Their Management. Healthcare (Basel) 2022;10:2519. [Crossref] [PubMed]
42. Zheng B, Zhou Q, Liu X, et al. Low-density pedicle screw in adolescent idiopathic scoliosis: a systematic review and meta-analysis of 1,762 patients. Front Surg 2025;12:1607323. [Crossref] [PubMed]
43. Aoun M, Daher M, Bizdikian AJ, et al. Implant density in adolescent idiopathic scoliosis: a meta-analysis of clinical and radiological outcomes. Spine Deform 2024;12:909-21. [Crossref] [PubMed]
44. Shaw KA, Ange B, George V, et al. Continued Increase in Cost of Care Despite Decrease in Stay After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis. J Am Acad Orthop Surg Glob Res Rev 2022;6:e21.00192.