Thoracoscopic Surgery in the Management of Idiopathic Scoliosis: Systematic Literature Review according to the Prisma Protocol

Abstract

Idiopathic scoliosis is characterized by a three-dimensional deformity of the spine with axial rotation and lateral inclination with an angle greater than 10° according to the Cobb method. Its approach can be conservative or surgical, depending on the degree of angulation, musculoskeletal development and age of the affected child or adolescent, or even depending on the functional impairment resulting from the condition. The aim of this study was to analyze the impact of videoassisted thoracoscopic surgery in the management of idiopathic scoliosis. This is a systematic literature review, built according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol and registered with PROSPERO under number CRD42022351466. The search for studies was performed between August 2022 and September of the same year, in bibliographic databases including MEDLINE, The Cochrane Library and Web of Science. The technique is a minimally invasive alternative to thoracotomy that has shown great evolution in recent years. The main advantages include less blood loss during the procedure, shorter hospital stay and improved post-surgical esthetics. One of the disadvantages mentioned by the authors is the greater complexity and technological requirement, longer surgical time and the need for careful selection of patients, according to degrees of vertebral deviation. The use of analgesics and anti-inflammatory drugs had no significant difference between traditional procedures (thoracotomy) or thoracoscopic surgery.

Keywords

scoliosis - thoracoscopic - minimally invasive surgery

Introduction

The Scoliosis Research Society (SRS) defines scoliosis as the lateral curvature of the spine with a Cobb angle greater than 10° in an anteroposterior radiograph with the patient in orthostasis.[1] [2]

Idiopathic scoliosis has a multifactorial etiology involving deficits in postural control by the central nervous system (CNS), hormonal components, polygenic inheritance, biomechanical spinal disorders, anomalous skeletal muscle conditions, and collagen disturbances.[3] [4] The therapeutic management of idiopathic scoliosis is extremely complex. The medical approach selection relies on the angular values of the spinal curvatures, progressiveness level, and skeletal maturation. Curvatures between 10° and 25° are described as “observational;” those ranging from 25° to 40° usually require a cast or corrective orthoses,¹ and curvatures higher than 40° to 45° are eligible for surgical approach.[5] [6]

Historically, the surgical approach is instrumented arthrodesis, with fixation of each vertebral segment by the posterior bone consolidation per se. Although there are several available methods, the Lea Plaza framework stands out. This method has been used for over 20 years and allows a three-dimensional and segmental correction. The Lea Plaza framework brings each vertebra to the midline using wires under the deviated vertebral lamina which are tethered to the implants. Next, arthrodesis is performed with a bone graft in the entire area to be fused with an iliac crest autograft or allograft.[7]

The advancement of surgical techniques resulted in several new approaches proposed to manage idiopathic scoliosis, such as magnetically controlled growth rods[6] and minimally invasive surgeries that seek to increase the quality of life, individualize treatment, and reduce the risks associated with traditional surgery.[8] [9] [10]

Mack et al.[11] were the first to describe video-assisted thoracoscopy, or video-assisted thoracic surgery, in 1993 to approach injuries in the thoracic spinal segments. According to these authors, the patients receive endotracheal anesthesia with a double-lumen tube for ipsilateral lung collapse. Next, patients are put in lateral recumbency and undergo unilateral mechanical ventilation. A 10-mm incision is made in the midaxillary line. The incision's height varies according to the spinal level accessed at the initial exploratory thoracoscopy. Then, a second trocar is placed. Most surgeries use three to four open trocars, not requiring carbon dioxide insufflation. At the end of the procedure, the lung is expanded under direct visualization, and radiography assesses lung expansion and the chest drain location.

The technique is a minimally invasive alternative to thoracotomy, and it may be performed with posterior and anterior spinal fusion at the same surgical time or in a staged manner.[12] [13] This study analyzes the impact of video-assisted thoracoscopy in idiopathic scoliosis management.

Materials and Methods

This systematic literature review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, and its PROSPERO registration number is CRD42022351466.

Studies queries occurred between August and September 2022 in the bibliographic databases MEDLINE, The Cochrane Library, and Web of Science.

We selected studies published from January 2017 to August 2022 in English, Portuguese, and Spanish. Before the final analysis, we redid the queries to identify any other studies for potential inclusion. Unpublished studies were not included. The condition or domain studied was idiopathic scoliosis and its correction by video-assisted thoracoscopy.

The main questions of the study were the following:

• Which is the impact of thoracoscopy in approaching idiopathic scoliosis?

• Which are the risks associated with thoracoscopy for idiopathic scoliosis?

• Which are the advantages of thoracoscopy for idiopathic scoliosis?

• Which are the disadvantages of thoracoscopy for idiopathic scoliosis?

Inclusion criteria were studies on constructs for children and adolescents with idiopathic scoliosis treated with thoracoscopic surgical procedures. Studies addressing scoliosis in adults and elderlies were excluded from the search.

We analyzed the applicability of thoracoscopy in idiopathic scoliosis management, eligibility criteria for the procedure, associated risks and benefits, a correlation between the procedure and postoperative functionality, and postoperative length of stay.

Two independent reviewers applied the eligibility criteria and selected the studies for inclusion in the systematic review. The researchers were blinded to the decisions of their peer. We gathered information on study design, study methodology, participant demographics (age, gender), and baseline characteristics (scoliosis degree, previous surgeries).

We used the Systematic Review Data Repository-Plus software and the Cochrane risk of bias tool to improve reliability. Outcomes synthesis was qualitative, including a combination of data from individual studies on benefits, risks, or both associated with thoracoscopy for idiopathic scoliosis correction.

Results

The search criteria and study selection identified 15 constructs for discussion. [Fig. 1] shows the process of study screening following the PRISMA methodology.

Fig. 1 Study selection process following the PRISMA protocol.

Discussion

It is a consensus in the literature that the development of new surgical techniques resulted in excellent outcomes in idiopathic scoliosis management. Surgical indication relies on a pathological curvature above 45°, functional restriction, and pain complaints.[14]

The standard thoracotomy approach consists of a posterolateral incision extending from the anterior axial line to the scapular region. In addition, the technique involves the division of the serratus anterior and latissimus dorsi muscles, which can lead to long thoracic nerve injury and muscle atrophy.[15] [16] Although modern thoracotomy techniques in the pediatric population try to spare critical muscles and not resect the costal arches, functional and operative risks remain significant aspects to consider when selecting a procedure.[17]

Thus, the traditional surgical techniques for idiopathic scoliosis include release and open anterior instrumentation, posterior instrumentation, and thoracoscopic approaches.[18] The magnitude, flexibility, and type of curvature determine the selection for thoracoscopic instrumentation. In all these surgeries, patients were in lateral recumbency, with the convex side of the thoracic curve placed superiorly. The authors used three to six portals to access the spine, performing a previous discectomy for subsequent screw insertion. The incisions were usually 2 to 3 cm long in the midaxillary line over the 3^rd, 5^th, 7^th, and 9^th ribs, or the 4^th, 6^th, 8^th, and 10^th ribs, depending on rib inclination and the trajectory of the instrumented vertebrae.[17] [18] [19] [20]

In skeletally immature children and a high degree of curvature, a major challenge is to perform surgery for scoliosis correction without limiting growth. In these cases, spinal fusion is not ideal, as it would limit thoracic growth and contribute to long-term lung impairment. Spinal fusion surgeries are often described in adolescents. Other options, such as magnetically controlled growth rods and expandable prostheses, have been described in younger children, even though adolescents may also benefit from such technologies.[18] [21] A retrospective cohort study assessed the impact of thoracoscopic surgery on 28 female adolescents with idiopathic scoliosis. The authors point out that, in addition to the biomechanical results, a significant aesthetic concern for patients is the anterior chest wall deformity. The thoracoscopic procedure improved the scoliotic condition, resulting in a lower anterior chest wall deformity. This study considered the following deformity parameters: the Cobb angle, rib hump, chest wall angle, and posterior apical deformity angle.[19]

Most studies described successful vertebral fusion and instrumentation performed thoracoscopically for idiopathic scoliosis management. However, Wong et al.[20] described a thoracoscopic technique for anterior vertebral body tethering, performing scoliosis correction with no need for vertebral fusion. The patients (n = 5) were 9 to 12 years old and had a mean preoperative main thoracic Cobb angle of 40.1°. Magnetic resonance imaging showed improvement in periapical disc wedge morphology and a 55% improvement in rotation in 3 years. However, two patients required a new corrective procedure with posterior spinal fusion, also thoracoscopically. It is worth noting that the authors considered the thoracoscopic method safe, both for the vertebral fusion technique and the vertebral body tethering.[17] [19] [20]

Crawford e Lenke[22] described the vertebral body tethering in 2010 resulting in growth modulation and progressive correction of the juvenile idiopathic scoliosis. Costanzo et al.[23] indicated the video-assisted thoracoscopy for vertebral body tethering in pre-adolescents with a scoliosis degree above 40°. All patients presented scoliosis reduction and significant functional gains.

In a retrospective study comparing posterior spinal fusion with anterior vertebral body tethering via thoracoscopic approach, both techniques resulted in postoperative correction; however, 2 years after the procedure, the scoliosis outcome was better in the group undergoing spinal fusion. It is worth noting patients undergoing thoracoscopic surgery and vertebral bodies tethering could postpone the posterior spinal fusion. This can be extremely beneficial in younger patients with immature skeletal development although the posterior vertebral fusion, even in an open surgery, is the gold standard for the definitive treatment of scoliosis with an angle greater than 45°.[24]

In skeletally immature individuals with idiopathic scoliosis, the thoracoscopic vertebral body tethering results in a satisfactory deformity correction and has an acceptable rate of complications.[25] In a study with 57 patients with a mean age of 12.7 years, the revision surgery rate was 15.8%. Patients with a coronal Cobb angle greater than 35° were considered clinical successes; their average curvature was 51° preoperatively and 24.6° at the first follow-up visit post-surgery. These subjects presented an average curvature of 16.3° 1 year after the procedure.[26]

Rushton et al.[27] obtained similar results when 112 patients with a mean age of 12.7 ± 1.4 years underwent thoracoscopy and vertebral body tethering. The average curvature before the procedure was 50.8° ± 10.2, whereas the average postoperative curvature was 26.6° ± 10.1. In this study, the revision surgery rate was 13%. The main complication was tethering rupture (22%), leading the authors to emphasize the need to develop better implants and improve the criteria for patient selection.

In a retrospective analysis of 5 years, including 20 patients aged 9 to 17 years old, the success rate was high (95%) after the follow-up period. The last Cobb angle on radiography at a mean follow-up of 5 years was 19.4°; in contrast, the average angle before the procedure was 47.4° (40° to 58°). Although the sample was small, the study reports that 5% of the patients required posterior fusion, which would be an extremely acceptable rate and validate the thoracoscopic vertebral body tethering.[28] A similar study with 27 patients undergoing a thoracoscopic procedure and vertebral body tethering had a success rate of 74%, with an overall revision rate of 21%. Tethering rupture was the main documented complication; in addition, it was suspected in 48% of the subjects. However, in some cases, the tethering rupture was not decisive to compromise the outcomes, and the scoliosis angle satisfactorily regressed. Spinal fusion was avoided in 93% of patients.[29] On the other hand, Hegde et al.[30] used thoracoscopy and vertebral body tethering in skeletally mature children with a mean age of 14.9 ± 2.7 years at the time of surgery. The mean preoperative Cobb angle was 52.0° ± 11.6° and 15.9° ± 6.8° on the first postoperative radiograph. There were no complications or the need for further surgical intervention. These outcomes suggested that the technique is an alternative to fusion for stabilizing progressive idiopathic scoliosis in skeletally mature children.

Pehlivanoglu et al.[31] conducted another study supporting the relevance of thoracoscopy and vertebral body tethering. These authors compared scoliosis correction and the functional degree of patients undergoing vertebral fusion by thoracotomy or vertebral bodies tethering via thoracoscopy. Both techniques were effective in correcting adolescent idiopathic scoliosis. However, the thoracoscopy group showed an improved superior lumbar range of motion, superior anterolateral lumbar flexion flexibility, superior trunk flexor and extensor resistance, and superior mean motor strength of trunk muscles with a high statistical significance compared with those who underwent a spinal fusion, directly affecting the quality of life and functionality.

[Table 1] summarizes the advantages and disadvantages of the thoracoscopic and thoracotomy approaches. It is worth noting that the thoracoscopic approach is a surgical approach to address scoliosis using bone grafts with subsequent vertebral fusion but may also be an approach for vertebral body tethering; this second technique was the most frequently mentioned.

Table 1

	Thoracoscopy	Thoracotomy
Advantages	- Lower bleeding and exposure to infections - Provides surgical access for definite interventions, including vertebral fusion or vertebral body wiring. - Effective scoliosis correction - Higher anterior and lateral lumbar flexibility and better truncal flexion compared with vertebral fusion	- Remains the gold standard in idiopathic scoliosis with an angle higher than 45° - Lower rate of revision surgeries - Effective scoliosis correction
Disadvantages	- Longer surgical time - May require procedural revision and evolution to open surgery	- Higher bleeding - Higher risk of infections - Small children may not be candidates for the procedure due to skeletal immaturity

Source: Authors (2022).

Final Considerations

Posterior spinal fusion is the gold standard technique for the surgical correction of idiopathic scoliosis. It is worth noting that surgical management is indicated in severe cases, characterized by an angle greater than 45° in the postural deviation. However, this technique is controversial because it limits growth and movement, and there are reports in the literature addressing chronic pain years after the correction.

With the advancement of surgical techniques, thoracoscopy has emerged as a therapeutic option for scoliotic patients. It allows the placement of a bone graft for fusion and vertebral body tethering, which would be better for younger children still presenting bone growth.

Most studies reported the thoracoscopic approach as safe and effective in idiopathic scoliosis. Vertebral body tethering would be a viable option for younger subjects; in contrast, the spinal fusion technique would be suitable for skeletally mature adolescents.

The thoracoscopic approach also has an advantage when analyzing bleeding risks, infection risks, and lengths of stay. However, surgical time tends to be longer than open surgery. This is especially true in vertebral body tethering, which is associated with a higher number of reinterventions and the need for future open surgery.

Conflito de Interesses

Os autores declaram não haver conflito de interesses.

Note

The paper “Thoracoscopic Surgery in the Management of Idiopathic Scoliosis: Systematic Literature Review according to the Prisma Protocol” is a systematic review using the PRISMA protocol, so it did not require a submission to the research ethics committee.

Study developed at the Nossa Senhora das Graças Hospital, Canoas, RS, Brazil.

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Publication History

Received: 06 September 2022

Accepted: 23 November 2022

Article published online:
08 December 2023