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Minimally invasive surgery in the treatment of adolescent idiopathic scoliosis: A literature review and meta-analysis
Journal of Orthopaedics 14 (2017) 19–22
Contents lists available at ScienceDirect
Journal of Orthopaedics journal homepage: www.elsevier.com/locate/jor
Review Article
Minimally invasive surgery in the treatment of adolescent idiopathic scoliosis: A literature review and meta-analysis Sandip P. Tarpada *, Matthew T. Morris Albert Einstein College of Medicine, New York, NY, United States
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 September 2016 Accepted 13 October 2016 Available online
Background context: Spinal fusion surgery for scoliosis can be performed using a traditional open approach, or by following a minimally invasive approach. Minimally invasive surgery (MIS) is associated with theoretical advantages, such as reduced blood loss and a shorter hospital stay, yet there is no consensus in the literature with regard to the best treatment approach for adolescent idiopathic scoliosis (AIS). Purpose: To assess the clinical outcomes of patients with AIS treated with either an open or minimally invasive approach. Study design: Systematic review and meta-analysis of English-language studies for the treatment of adolescent idiopathic scoliosis. Patient sample: Pooled results from level 1 and 2 studies. Methods: We carried out a systematic literature search of EMBASE and MEDLINE, identifying studies investigating MIS in the treatment of AIS. Percentages of curvature correction were pooled and analysed. Results: The literature search returned 50 articles, of which we determined 4 studies to be relevant. The pooled percentage curve correction across these groups was 62.05% for the MIS group and 70% for the open surgery group. Although these data are significant (p = 0.001), the available studies are of variable quality, and sample sizes small. Conclusions: Patients with adolescent idiopathic scoliosis can be managed with either a traditional open approach or a minimally invasive approach. The data suggests that open surgery offers an advantage in terms of curve correction, compared to minimally invasive surgery, however more investigation (in the form of robust randomized control trials) is needed before conclusive clinical suggestions can be recommended. ß 2016 Prof. PK Surendran Memorial Education Foundation. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.
Keywords: Minimally invasive surgery Adolescent idiopathic scoliosis
1. Introduction Physicians may recommend minimally invasive surgery to their patients over open surgery based on the fact that it has a lower rate of wound infection,1 reduced tissue damage, blood loss, length of hospital stay, and use of analgesics, along with an earlier resumption of activities of daily maintenance.2 However at this time there is no clear consensus as to whether a minimally invasive approach is preferable to the open approach in terms of overall curve correction. Considering that there is also little evidence supporting the use of surgical techniques in the treatment of AIS when compared to less invasive techniques such as exercise or bracing,3 these data call attention to the need for further research
* Corresponding author. E-mail address: [email protected] (S.P. Tarpada).
in this field far more eloquently than they support a particular intervention. When recommending interventions to their patients, physicians are not always guided by the best evidence, particularly when no such evidence exists; this phenomenon becomes especially clear when we consider the case of adolescent idiopathic scoliosis (AIS). A Cochrane review carried out in 2015 found that no conclusion could be drawn from the literature with regard to surgical versus non-surgical interventions in severe AIS; this study was an ‘‘empty review’’ which nonetheless highlighted the alarming dearth of research in this field.3 Likewise, an earlier review found no evidence that the health-related aspects of AIS can be altered in any significant way by surgical intervention, concluding that there is no medical justification for an intervention which is associated with a high rate of complications.4 AIS does not inevitably end in disability. A prospective natural history study showed that untreated adolescent idiopathic
http://dx.doi.org/10.1016/j.jor.2016.10.006 0972-978X/ß 2016 Prof. PK Surendran Memorial Education Foundation. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.
20
S.P. Tarpada, M.T. Morris / Journal of Orthopaedics 14 (2017) 19–22
scoliosis is not associated significantly with any physical impairment, other than shortness of breath and moderate back pain.5 However, AIS is associated with an impairment of healthrelated quality of life, such as depression.6 Consideration should be given to both the physical and the psychosocial situation that arises due to the deformity, when discussing treatment options and morbidity, especially when the surgical aims for the correction of AIS are generally quite modest: the prevention of progression, or rending the curve more ‘‘acceptable’’. There is a lack of randomized control studies supporting the efficacy of either conservative or surgical treatments for AIS.7 It is possible that the morbidity of the open surgical procedure outweighs the benefits of the intervention.8 Can the same be said of the minimally invasive procedure? Is MIS an effective treatment for AIS when compared to open surgery?
to percentages in accordance with the procedure for calculating the correction rate put forth by Lee et al.,10 however, this study was discarded at the full text screen because there was no control. We assessed statistical heterogeneity by carrying out a chi-squared test, in order to determine whether the any observed differences between the studies could be explained by recourse to chance alone. Effect size was calculated using Cohen’s d.
1.1. Rationale and objectives
We assessed the studies for publication bias, selection bias, performance bias, detection bias, and reporting bias.
Given that minimally invasive spine surgery is becoming more common in the treatment of various spinal conditions, owing generally to the fact that a minimally invasive approach curtails iatrogenic trauma, we sought to determine whether those with AIS are better treated with MIS as compared to traditional open surgery, using curve correction (percentage) as a measure of efficacy. Additionally, we discuss the implications of our data of those found in the AIS literature at large. 2. Methods We performed a PRISMA-compliant literature search using EMBASE and MEDLINE. The electronic databases were searched from January, 1980, through August, 2016, the rationale for these limits being that minimally invasive surgery has only generally been carried out on adolescents with AIS over the last couple of decades. We performed the searches in accordance with Medical Subject Headings. Search terms included were ‘‘scoliosis’’, ‘‘adolescent idiopathic scoliosis,’’ ‘‘minimally invasive surgery,’’ ‘‘arthroscopy,’’ ‘‘arthroscopic,’’ ‘‘thorascopic,’’ and ‘‘MISS’’. Both terms were searched as subject headings and keywords. Results that were not in English, those that contained adult patients, and those with no available abstract were strictly excluded. The inclusion criteria for our meta-analysis were as follows:
2.3. Risk of bias in individual studies We assessed each study for risk of any bias that would result in heterogeneity of results, in accordance with the Cochrane Handbook. 2.4. Risk of bias across studies
3. Results 3.1. Study characteristics The initial search resulted in 50 articles. After two-reviewer assessment, we identified 19 articles that met the inclusion criteria. Following a full text screen, 15 articles were excluded for a variety of reasons including poor study design,9 insufficient cohort size11 or because subjects were not limited to those with AIS (see Fig. 1). There were two prospective evaluations and two retrospective analyses. There were no randomized control trials. Descriptive information for each trial is given in Table 1. Overall, 272 patients were treated for AIS, with 132 of those patients receiving MIS. All of the studies provided standard deviation and confidence intervals. 3.2. Summary of investigations Faro et al. performed a prospective evaluation of pulmonary function in patients with AIS undergoing either an open or a
1. Prospective studies on subjects diagnosed with AIS that reported post-operative percentage of curvature correction. 2. Subjects were treated with MIS. 3. Studies had a minimum of 10 patients, and compared MIS group to a control that underwent open surgery. These criteria were developed in line with the PICO guidelines for developing robust questions in evidence-based medicine. 2.1. Study selection All articles underwent primary abstract review, after which a selection that met our predefined criteria, underwent full text review. We assessed the quality of the evidence offered in each study in accordance with the 2011 Oxford Centre for EvidenceBased Medicine Levels of Evidence. 2.2. Data collection, data items, summary measures, and synthesis of results We extracted two metrics from each study, the mean correction percentage for MIS, and the mean correction percentage for traditional open surgery. The results of one study9 were converted
Fig. 1. Study selection process.
S.P. Tarpada, M.T. Morris / Journal of Orthopaedics 14 (2017) 19–22 Table 1 Summary of studies included in the meta-analysis. Study name
Level of evidence 12
Faro et al., 2005 Lee et al., 201310 Kishan et al., 200713 Miyanji and Desai, 201514
2b 2b 1b 2b
21
Table 2 Synthesis of results. Total no. of patients 54 65 107 46
Study name 12
Faro et al., 2005 Lee et al., 201310 Kishan et al., 200713 Miyanji and Desai, 201514
Effect size
95% CI
Variance
0.4591 0.4714 0.2901 5.0282
0.0872 0.0435 0.1128 3.808
0.0777 0.069 0.0423 0.3563
Total: 272.
minimally invasive procedure. They also measured curve correction. In the group that underwent a thoracoscopic spinal fusion (n = 23), there was an average curve correction of 59% (10%), compared to 54% (12%) in the open group (n = 31). Kishan et al. carried out a prospective evaluation of pulmonary function with 107 patients in a multicenter database. In the group which underwent the MIS procedure, a thoracoscopic instrumentation (n = 36), the average curve correction was 60% (13%), as compared to the two open groups (which underwent a thoracotomy with [n = 28] and without thoracoplasty [n = 43], respectively), for which the average curve correction was 52% (20%) for the group without thoracoplasty and 58% (18%) for the group with thoracoplasty. Lee et al. carried out a retrospective comparative study comparing an MIS procedure with the traditional open approach. All the procedures were performed by a single surgeon. Lee et al. found that there was a greater curve correction in the group which underwent the open surgery, 71% (11%), compared to the MIS group, in which the average curve correction was 66% (13%). Miyanji and Desai carried out a retrospective analysis of prospectively collected data from a multicenter database. 23 patients who underwent an MIS procedure were matched with a control of 23 patients who underwent a standard open procedure. The average curve correction in the MIS group was 58% (2%) and 68% (1%) in the open group (Table 2). 3.3. Clinical results The pooled percentage curve correction across these groups was 62.05% for the MIS group and 70% for the open surgery group. Although these data are significant (p = 0.001), the studies are highly heterogeneous (see Fig. 2). 4. Discussion 4.1. Discussion of the main results In many ways, statistical significance is the least interesting thing about the results when carrying out a meta-analysis.15 The p value can inform a reader that an effect exists, but not any
information about the degree of its magnitude. Meta-analyses allow for data from studies to be combined to determine if there is a significant effect, and the magnitude of that effect. We can make ourselves tentatively aware that open surgery is more effective in treating the curve, when measuring overall curve correction, but to what extent can we trust this conclusion? Three of these studies have extremely small effect sizes, while the results from Miyanji et al. are a large effect size. Considering that the sample size is small, and that the results tend to be heterogenous, our data does not support any specific conclusion. Minimally invasive surgery is often recommended by surgeons on the basis that it is less invasive, yet if any closing can be made from this data, it is that the minimally invasive procedure is less effective in treating the curve. The ‘‘less invasive’’ explanation for the surgery, in this context, seems quite tautological. Two of the studies included in this meta-analysis were designed to assess the impact of MIS on lung function, as compared to controls who underwent traditional open surgery. These results were statistically significant, with MIS patients performing better on several measures of lung function. This data is certainly significant when it comes to assessing the overall benefit of the MIS procedure, but it must be considered alongside the other conclusions of this study. This literature review highlights what other studies and reviews have also been forced to conclude: there currently exists no definitive scientific evidence with regard to the efficacy of surgical treatments for AIS, or for the benefit of those interventions over conservative treatments. Therefore, while we were able to conclude that minimally invasive surgery is less effective than traditional open surgery in terms of curve correction, we feel that there is a caveat concerning the validity of these results: more research is needed to determine whether any surgical intervention for AIS is preferable to a less invasive treatment, before determining more robustly whether the reduced curve correction in MIS is an acceptable trade-off, considering that even minimally invasive surgery carries with it risks and morbidities. When the scientific evidence is not clear, physicians make decisions based on beliefs. We believe the only responsible conclusion that can be
Fig. 2. Mean differences in curvature correction.
22
S.P. Tarpada, M.T. Morris / Journal of Orthopaedics 14 (2017) 19–22
taken from these data is that more research is needed for any practice to be evidence-based. There are grey areas in the treatment of scoliosis in which it is impossible to give an evidence-based justification for clinical practice,16 and in this case evidence, clinical expertise, and patient preferences combine. The issue here, however, is not the impossibility of evidence, but a lack of research. Conflicts of interest The authors have none to declare. References 1. Smith JS, Shaffrey CI, Sansur CA, et al. Rates of infection after spine surgery based on 108,419 procedures: a report from the Scoliosis Research Society Morbidity and Mortality Committee. Spine (Phila Pa 1976). 2011;36(7):556–563. 2. McAfee PC, Phillips FM, Andersson G, et al. Minimally invasive spine surgery. Spine (Phila Pa 1976). 2010;35(26 suppl):S271–S273. 3. Bettany-Saltikov J, Weiss HR, Chockalingam N, et al. Surgical versus non-surgical interventions in people with adolescent idiopathic scoliosis. Cochrane Library. 2015. 4. Weiss HR, Goodall D. Rate of complications in scoliosis surgery – a systematic review of the Pub Med literature. Scoliosis. 2008;3:9. 5. Weinstein SL, Dolan LA, Spratt KF, Peterson KK, Spoonamore MJ, Ponseti IV. Health and function of patients with untreated idiopathic scoliosis: a 50-year natural history study. JAMA. 2003;289(5):559–567.
6. Freidel K, Petermann F, Reichel D, Steiner A, Warschburger P, Weiss HR. Quality of life in women with idiopathic scoliosis. Spine (Phila Pa 1976). 2002;27(4):E87–E91. 7. Negrini S, Grivas TB, Kotwicki T, et al. Why do we treat adolescent idiopathic scoliosis? What we want to obtain and to avoid for our patients. SOSORT 2005 Consensus paper. Scoliosis. 2006;1:4. 8. Youssef JA, McAfee PC, Patty CA, et al. Minimally invasive surgery: lateral approach interbody fusion: results and review. Spine (Phila Pa 1976). 2010;35(26 suppl): S302–S311. 9. Picetti 3rd GD, Ertl JP, Bueff HU. Endoscopic instrumentation, correction, and fusion of idiopathic scoliosis. Spine J. 2001;1(3):190–197. 10. Lee CS, Park SJ, Chung SS, Kang KC, Jung CH, Kim YT. A comparative study between thoracoscopic surgery and posterior surgery using all-pedicle-screw constructs in the treatment of adolescent idiopathic scoliosis. J Spinal Disord Techn. 2013;26(6): 325–333. 11. Namboothiri S, Kumar R, Menon KV. Early changes in pulmonary function following thoracotomy for scoliosis correction: the effect of size of incision. Eur Spine J. 2005;14(2):144–148. 12. Faro FD, Marks MC, Newton PO, Blanke K, Lenke LG. Perioperative changes in pulmonary function after anterior scoliosis instrumentation: thoracoscopic versus open approaches. Spine (Phila Pa 1976). 2005;30(9):1058–1063. 13. Kishan S, Bastrom T, Betz RR, et al. Thoracoscopic scoliosis surgery affects pulmonary function less than thoracotomy at 2 years postsurgery. Spine (Phila Pa 1976). 2007;32(4):453–458. 14. Miyanji F, Desai S. Minimally invasive surgical options for adolescent idiopathic scoliosis. Paper presented at Seminars in Spine Surgery, 2015. 15. Sullivan GM, Feinn R. Using effect size-or why the P value is not enough. J Grad Med Educ. 2012;4(3):279–282. 16. Negrini S, Aulisa AG, Aulisa L, et al. 2011 SOSORT guidelines: orthopaedic and rehabilitation treatment of idiopathic scoliosis during growth. Scoliosis. 2012; 7(1):3.
Contents lists available at ScienceDirect
Journal of Orthopaedics journal homepage: www.elsevier.com/locate/jor
Review Article
Minimally invasive surgery in the treatment of adolescent idiopathic scoliosis: A literature review and meta-analysis Sandip P. Tarpada *, Matthew T. Morris Albert Einstein College of Medicine, New York, NY, United States
A R T I C L E I N F O
A B S T R A C T
Article history: Received 21 September 2016 Accepted 13 October 2016 Available online
Background context: Spinal fusion surgery for scoliosis can be performed using a traditional open approach, or by following a minimally invasive approach. Minimally invasive surgery (MIS) is associated with theoretical advantages, such as reduced blood loss and a shorter hospital stay, yet there is no consensus in the literature with regard to the best treatment approach for adolescent idiopathic scoliosis (AIS). Purpose: To assess the clinical outcomes of patients with AIS treated with either an open or minimally invasive approach. Study design: Systematic review and meta-analysis of English-language studies for the treatment of adolescent idiopathic scoliosis. Patient sample: Pooled results from level 1 and 2 studies. Methods: We carried out a systematic literature search of EMBASE and MEDLINE, identifying studies investigating MIS in the treatment of AIS. Percentages of curvature correction were pooled and analysed. Results: The literature search returned 50 articles, of which we determined 4 studies to be relevant. The pooled percentage curve correction across these groups was 62.05% for the MIS group and 70% for the open surgery group. Although these data are significant (p = 0.001), the available studies are of variable quality, and sample sizes small. Conclusions: Patients with adolescent idiopathic scoliosis can be managed with either a traditional open approach or a minimally invasive approach. The data suggests that open surgery offers an advantage in terms of curve correction, compared to minimally invasive surgery, however more investigation (in the form of robust randomized control trials) is needed before conclusive clinical suggestions can be recommended. ß 2016 Prof. PK Surendran Memorial Education Foundation. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.
Keywords: Minimally invasive surgery Adolescent idiopathic scoliosis
1. Introduction Physicians may recommend minimally invasive surgery to their patients over open surgery based on the fact that it has a lower rate of wound infection,1 reduced tissue damage, blood loss, length of hospital stay, and use of analgesics, along with an earlier resumption of activities of daily maintenance.2 However at this time there is no clear consensus as to whether a minimally invasive approach is preferable to the open approach in terms of overall curve correction. Considering that there is also little evidence supporting the use of surgical techniques in the treatment of AIS when compared to less invasive techniques such as exercise or bracing,3 these data call attention to the need for further research
* Corresponding author. E-mail address: [email protected] (S.P. Tarpada).
in this field far more eloquently than they support a particular intervention. When recommending interventions to their patients, physicians are not always guided by the best evidence, particularly when no such evidence exists; this phenomenon becomes especially clear when we consider the case of adolescent idiopathic scoliosis (AIS). A Cochrane review carried out in 2015 found that no conclusion could be drawn from the literature with regard to surgical versus non-surgical interventions in severe AIS; this study was an ‘‘empty review’’ which nonetheless highlighted the alarming dearth of research in this field.3 Likewise, an earlier review found no evidence that the health-related aspects of AIS can be altered in any significant way by surgical intervention, concluding that there is no medical justification for an intervention which is associated with a high rate of complications.4 AIS does not inevitably end in disability. A prospective natural history study showed that untreated adolescent idiopathic
http://dx.doi.org/10.1016/j.jor.2016.10.006 0972-978X/ß 2016 Prof. PK Surendran Memorial Education Foundation. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.
20
S.P. Tarpada, M.T. Morris / Journal of Orthopaedics 14 (2017) 19–22
scoliosis is not associated significantly with any physical impairment, other than shortness of breath and moderate back pain.5 However, AIS is associated with an impairment of healthrelated quality of life, such as depression.6 Consideration should be given to both the physical and the psychosocial situation that arises due to the deformity, when discussing treatment options and morbidity, especially when the surgical aims for the correction of AIS are generally quite modest: the prevention of progression, or rending the curve more ‘‘acceptable’’. There is a lack of randomized control studies supporting the efficacy of either conservative or surgical treatments for AIS.7 It is possible that the morbidity of the open surgical procedure outweighs the benefits of the intervention.8 Can the same be said of the minimally invasive procedure? Is MIS an effective treatment for AIS when compared to open surgery?
to percentages in accordance with the procedure for calculating the correction rate put forth by Lee et al.,10 however, this study was discarded at the full text screen because there was no control. We assessed statistical heterogeneity by carrying out a chi-squared test, in order to determine whether the any observed differences between the studies could be explained by recourse to chance alone. Effect size was calculated using Cohen’s d.
1.1. Rationale and objectives
We assessed the studies for publication bias, selection bias, performance bias, detection bias, and reporting bias.
Given that minimally invasive spine surgery is becoming more common in the treatment of various spinal conditions, owing generally to the fact that a minimally invasive approach curtails iatrogenic trauma, we sought to determine whether those with AIS are better treated with MIS as compared to traditional open surgery, using curve correction (percentage) as a measure of efficacy. Additionally, we discuss the implications of our data of those found in the AIS literature at large. 2. Methods We performed a PRISMA-compliant literature search using EMBASE and MEDLINE. The electronic databases were searched from January, 1980, through August, 2016, the rationale for these limits being that minimally invasive surgery has only generally been carried out on adolescents with AIS over the last couple of decades. We performed the searches in accordance with Medical Subject Headings. Search terms included were ‘‘scoliosis’’, ‘‘adolescent idiopathic scoliosis,’’ ‘‘minimally invasive surgery,’’ ‘‘arthroscopy,’’ ‘‘arthroscopic,’’ ‘‘thorascopic,’’ and ‘‘MISS’’. Both terms were searched as subject headings and keywords. Results that were not in English, those that contained adult patients, and those with no available abstract were strictly excluded. The inclusion criteria for our meta-analysis were as follows:
2.3. Risk of bias in individual studies We assessed each study for risk of any bias that would result in heterogeneity of results, in accordance with the Cochrane Handbook. 2.4. Risk of bias across studies
3. Results 3.1. Study characteristics The initial search resulted in 50 articles. After two-reviewer assessment, we identified 19 articles that met the inclusion criteria. Following a full text screen, 15 articles were excluded for a variety of reasons including poor study design,9 insufficient cohort size11 or because subjects were not limited to those with AIS (see Fig. 1). There were two prospective evaluations and two retrospective analyses. There were no randomized control trials. Descriptive information for each trial is given in Table 1. Overall, 272 patients were treated for AIS, with 132 of those patients receiving MIS. All of the studies provided standard deviation and confidence intervals. 3.2. Summary of investigations Faro et al. performed a prospective evaluation of pulmonary function in patients with AIS undergoing either an open or a
1. Prospective studies on subjects diagnosed with AIS that reported post-operative percentage of curvature correction. 2. Subjects were treated with MIS. 3. Studies had a minimum of 10 patients, and compared MIS group to a control that underwent open surgery. These criteria were developed in line with the PICO guidelines for developing robust questions in evidence-based medicine. 2.1. Study selection All articles underwent primary abstract review, after which a selection that met our predefined criteria, underwent full text review. We assessed the quality of the evidence offered in each study in accordance with the 2011 Oxford Centre for EvidenceBased Medicine Levels of Evidence. 2.2. Data collection, data items, summary measures, and synthesis of results We extracted two metrics from each study, the mean correction percentage for MIS, and the mean correction percentage for traditional open surgery. The results of one study9 were converted
Fig. 1. Study selection process.
S.P. Tarpada, M.T. Morris / Journal of Orthopaedics 14 (2017) 19–22 Table 1 Summary of studies included in the meta-analysis. Study name
Level of evidence 12
Faro et al., 2005 Lee et al., 201310 Kishan et al., 200713 Miyanji and Desai, 201514
2b 2b 1b 2b
21
Table 2 Synthesis of results. Total no. of patients 54 65 107 46
Study name 12
Faro et al., 2005 Lee et al., 201310 Kishan et al., 200713 Miyanji and Desai, 201514
Effect size
95% CI
Variance
0.4591 0.4714 0.2901 5.0282
0.0872 0.0435 0.1128 3.808
0.0777 0.069 0.0423 0.3563
Total: 272.
minimally invasive procedure. They also measured curve correction. In the group that underwent a thoracoscopic spinal fusion (n = 23), there was an average curve correction of 59% (10%), compared to 54% (12%) in the open group (n = 31). Kishan et al. carried out a prospective evaluation of pulmonary function with 107 patients in a multicenter database. In the group which underwent the MIS procedure, a thoracoscopic instrumentation (n = 36), the average curve correction was 60% (13%), as compared to the two open groups (which underwent a thoracotomy with [n = 28] and without thoracoplasty [n = 43], respectively), for which the average curve correction was 52% (20%) for the group without thoracoplasty and 58% (18%) for the group with thoracoplasty. Lee et al. carried out a retrospective comparative study comparing an MIS procedure with the traditional open approach. All the procedures were performed by a single surgeon. Lee et al. found that there was a greater curve correction in the group which underwent the open surgery, 71% (11%), compared to the MIS group, in which the average curve correction was 66% (13%). Miyanji and Desai carried out a retrospective analysis of prospectively collected data from a multicenter database. 23 patients who underwent an MIS procedure were matched with a control of 23 patients who underwent a standard open procedure. The average curve correction in the MIS group was 58% (2%) and 68% (1%) in the open group (Table 2). 3.3. Clinical results The pooled percentage curve correction across these groups was 62.05% for the MIS group and 70% for the open surgery group. Although these data are significant (p = 0.001), the studies are highly heterogeneous (see Fig. 2). 4. Discussion 4.1. Discussion of the main results In many ways, statistical significance is the least interesting thing about the results when carrying out a meta-analysis.15 The p value can inform a reader that an effect exists, but not any
information about the degree of its magnitude. Meta-analyses allow for data from studies to be combined to determine if there is a significant effect, and the magnitude of that effect. We can make ourselves tentatively aware that open surgery is more effective in treating the curve, when measuring overall curve correction, but to what extent can we trust this conclusion? Three of these studies have extremely small effect sizes, while the results from Miyanji et al. are a large effect size. Considering that the sample size is small, and that the results tend to be heterogenous, our data does not support any specific conclusion. Minimally invasive surgery is often recommended by surgeons on the basis that it is less invasive, yet if any closing can be made from this data, it is that the minimally invasive procedure is less effective in treating the curve. The ‘‘less invasive’’ explanation for the surgery, in this context, seems quite tautological. Two of the studies included in this meta-analysis were designed to assess the impact of MIS on lung function, as compared to controls who underwent traditional open surgery. These results were statistically significant, with MIS patients performing better on several measures of lung function. This data is certainly significant when it comes to assessing the overall benefit of the MIS procedure, but it must be considered alongside the other conclusions of this study. This literature review highlights what other studies and reviews have also been forced to conclude: there currently exists no definitive scientific evidence with regard to the efficacy of surgical treatments for AIS, or for the benefit of those interventions over conservative treatments. Therefore, while we were able to conclude that minimally invasive surgery is less effective than traditional open surgery in terms of curve correction, we feel that there is a caveat concerning the validity of these results: more research is needed to determine whether any surgical intervention for AIS is preferable to a less invasive treatment, before determining more robustly whether the reduced curve correction in MIS is an acceptable trade-off, considering that even minimally invasive surgery carries with it risks and morbidities. When the scientific evidence is not clear, physicians make decisions based on beliefs. We believe the only responsible conclusion that can be
Fig. 2. Mean differences in curvature correction.
22
S.P. Tarpada, M.T. Morris / Journal of Orthopaedics 14 (2017) 19–22
taken from these data is that more research is needed for any practice to be evidence-based. There are grey areas in the treatment of scoliosis in which it is impossible to give an evidence-based justification for clinical practice,16 and in this case evidence, clinical expertise, and patient preferences combine. The issue here, however, is not the impossibility of evidence, but a lack of research. Conflicts of interest The authors have none to declare. References 1. Smith JS, Shaffrey CI, Sansur CA, et al. Rates of infection after spine surgery based on 108,419 procedures: a report from the Scoliosis Research Society Morbidity and Mortality Committee. Spine (Phila Pa 1976). 2011;36(7):556–563. 2. McAfee PC, Phillips FM, Andersson G, et al. Minimally invasive spine surgery. Spine (Phila Pa 1976). 2010;35(26 suppl):S271–S273. 3. Bettany-Saltikov J, Weiss HR, Chockalingam N, et al. Surgical versus non-surgical interventions in people with adolescent idiopathic scoliosis. Cochrane Library. 2015. 4. Weiss HR, Goodall D. Rate of complications in scoliosis surgery – a systematic review of the Pub Med literature. Scoliosis. 2008;3:9. 5. Weinstein SL, Dolan LA, Spratt KF, Peterson KK, Spoonamore MJ, Ponseti IV. Health and function of patients with untreated idiopathic scoliosis: a 50-year natural history study. JAMA. 2003;289(5):559–567.
6. Freidel K, Petermann F, Reichel D, Steiner A, Warschburger P, Weiss HR. Quality of life in women with idiopathic scoliosis. Spine (Phila Pa 1976). 2002;27(4):E87–E91. 7. Negrini S, Grivas TB, Kotwicki T, et al. Why do we treat adolescent idiopathic scoliosis? What we want to obtain and to avoid for our patients. SOSORT 2005 Consensus paper. Scoliosis. 2006;1:4. 8. Youssef JA, McAfee PC, Patty CA, et al. Minimally invasive surgery: lateral approach interbody fusion: results and review. Spine (Phila Pa 1976). 2010;35(26 suppl): S302–S311. 9. Picetti 3rd GD, Ertl JP, Bueff HU. Endoscopic instrumentation, correction, and fusion of idiopathic scoliosis. Spine J. 2001;1(3):190–197. 10. Lee CS, Park SJ, Chung SS, Kang KC, Jung CH, Kim YT. A comparative study between thoracoscopic surgery and posterior surgery using all-pedicle-screw constructs in the treatment of adolescent idiopathic scoliosis. J Spinal Disord Techn. 2013;26(6): 325–333. 11. Namboothiri S, Kumar R, Menon KV. Early changes in pulmonary function following thoracotomy for scoliosis correction: the effect of size of incision. Eur Spine J. 2005;14(2):144–148. 12. Faro FD, Marks MC, Newton PO, Blanke K, Lenke LG. Perioperative changes in pulmonary function after anterior scoliosis instrumentation: thoracoscopic versus open approaches. Spine (Phila Pa 1976). 2005;30(9):1058–1063. 13. Kishan S, Bastrom T, Betz RR, et al. Thoracoscopic scoliosis surgery affects pulmonary function less than thoracotomy at 2 years postsurgery. Spine (Phila Pa 1976). 2007;32(4):453–458. 14. Miyanji F, Desai S. Minimally invasive surgical options for adolescent idiopathic scoliosis. Paper presented at Seminars in Spine Surgery, 2015. 15. Sullivan GM, Feinn R. Using effect size-or why the P value is not enough. J Grad Med Educ. 2012;4(3):279–282. 16. Negrini S, Aulisa AG, Aulisa L, et al. 2011 SOSORT guidelines: orthopaedic and rehabilitation treatment of idiopathic scoliosis during growth. Scoliosis. 2012; 7(1):3.