Surgery is an Effective and Reasonable Treatment for Degenerative Scoliosis: a Systematic Review

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1 The Journal of International Medical Research 2012; 40: Surgery is an Effective and Reasonable Treatment for Degenerative Scoliosis: a Systematic Review C-Z LIANG, F-C LI, H LI, Y TAO, X ZHOU AND Q-X CHEN Department of Orthopaedic Surgery, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China OBJECTIVE: A systematic review to evaluate the role of surgery for treating degenerative scoliosis (DS) in terms of improved function (Oswestry Disability Index [ODI]) and correction of deformity (Cobb angle); safety outcomes included complication and repeat surgery rates. METHODS: A search of the MEDLINE, ISI Web of Knowledge and Cochrane Library databases was performed. The methodological quality of each study was assessed according to standardized criteria and data were extracted. RESULTS: A total of 16 studies including 553 patients with DS met the eligibility criteria for inclusion. The mean ODI score at final follow-up was 36.0 ± 7.8 (304 patients) and the mean decrease in ODI was 23.3 ± 11.3 (302 patients). Mean reduction in curve angle (as a percentage of the original curve) was 48.5 ± 21.0% (527 patients). The overall incidence of complications was 49.0% (171 in 349 patients) and the rate of repeat surgery was 15.3% (61 in 398 patients). CONCLUSIONS: Despite a high incidence of complications and reoperations, surgery was an effective and reasonable treatment for DS, providing significant functional improvement and deformity correction. KEY WORDS: DEGENERATIVE SCOLIOSIS; SURGERY; OSWESTRY DISABILITY INDEX; COBB ANGLE; COMPLICATION RATE; REOPERATION RATE; SYSTEMATIC REVIEW Introduction Degenerative scoliosis (DS), also known as primary degenerative scoliosis or de novo scoliosis, occurs in elderly adults without a previous history of scoliosis, 1 3 and affects approximately 6% of those aged > 50 years. 4 It is defined as a spinal deformity that develops after skeletal maturity, with a Cobb angle of > 10 in the coronal plane due to asymmetric disc and facet joint degeneration. 5 The incidence of DS has increased concurrently with life expectancy. 1,5 Nonsurgical treatment is generally sufficient to relieve pain and restore normal activity, 5 7 but a systematic review found that there was very weak evidence of success for any nonsurgical treatment options for adults with DS. 6 Surgery is mainly indicated for severe back pain and/or progressive neurological symptoms refractory to nonsurgical treatment, 1,5,8 and for significant deformity per se. 9 Few large-scale studies have assessed functional improvement, deformity correction, and complications and repeat operations following surgery for patients 399

2 with DS. 10,11 These studies suggest that due to advanced age, osteoporosis, comorbidities and spinal imbalance, surgery for DS is associated with considerable complications, and severe back pain and disability may persist postoperatively. 10,11 For surgery to be considered as an effective and reasonable treatment it should improve function, correct deformity and have a relatively low incidence of complications and repeat surgery. The current systematic review was undertaken to evaluate the role of surgery for treating DS and to determine whether surgery can improve function (based on the Oswestry Disability Index [ODI] 12 ) and correct deformities (Cobb angle). Rates of complications and repeat surgery were also evaluated. Materials and methods LITERATURE SEARCH STRATEGY Electronic database searches of MEDLINE (from January 1950 to December 2010), ISI Web of Knowledge (from January 1960 to December 2010), and the Cochrane Library (Issue 12, December 2010) were performed on 31 December The following terms were used to search the key words, abstract and title fields: (degenerative scoliosis OR de novo scoliosis) AND (surgery OR operation). Two reviewers (C.-Z.L. and F.-C.L.) independently evaluated the titles, abstracts and full texts to select appropriate studies. If there was any question as to the relevance of any article, a consensus was taken among all authors. The reference lists of selected articles were also reviewed to identify any additional studies. INCLUSION AND EXCLUSION CRITERIA The following were eligible for inclusion: (i) clinical studies; (ii) randomized controlled trials; (iii) controlled clinical trials with quasi-randomized methods; (iv) prospective studies; (v) retrospective studies; (vi) case series; and (vii) studies involving patients with a preoperative Cobb angle > 10. Excluded were: (i) articles not in English; (ii) animal studies; (iii) review articles or letters to the editor; (iv) studies involving patients of age < 40 years at the time of presentation; (v) studies involving patients with previous spine surgery or trauma, metabolic spinal pathology, asymmetrical anomalies at the lumbosacral junction, and a history of adolescent scoliosis or kyphosis, ankylosing spondylitis or osteoporotic vertebral fracture; (vi) studies involving patients with a preoperative Cobb angle 10 ; (vii) studies that included nonsurgical treatment; (viii) studies with a duration of follow-up < 2 years; (ix) studies in which the specific outcome data were not presented or could not be transformed into a compatible format for use in this review. CRITICAL APPRAISAL Two reviewers (C.-Z.L. and F.-C.L.) assessed the methodological quality and extracted the data from each study independently; disagreement was resolved by discussion and, if necessary, by consensus of all authors. Data quality (level of evidence) was classified from class I to class V according to a previous report, 13 with class I being the strongest (randomized controlled trials) and class V being the weakest (expert opinion). Additionally, the methodological quality of the studies was assessed according to the modified Jadad scale (MJS) 14 for randomized controlled trials and the methodological index for non-randomized studies (MINORS) for nonrandomized studies. 15 The MJS score ranged from 0 to 8, with high quality defined as 4. MINORS comprises 12 items, with an ideal score of 16 for noncomparative studies and 24 for comparative studies. 400

3 DATA EXTRACTION Data on three specific outcomes were extracted: (i) function (ODI and change in ODI); (ii) deformity correction (Cobb angle, curve reduction and curve reduction as a percentage of the original curve); and (iii) incidence of complications and repeat surgeries. DATA ANALYSES Weighted means of age, duration of followup, preoperative ODI, ODI at final follow-up, change in ODI, Cobb angles, curve reduction, curve reduction as a percentage of the original curve, and the incidence of complications and repeat surgery were calculated. A pooled analysis of the data recorded in the individual studies was undertaken. The incidence of complications was calculated as the total number of complications divided by the total number of patients in the reported studies. The incidence of repeat surgery was calculated as the total number of patients who underwent repeat surgery divided by the total number of patients in the reported studies. SPSS version 10.0 (SPSS Inc., Chicago, IL, USA) for Windows was used for data processing. Results The literature search retrieved 322 articles from MEDLINE, 359 from ISI Web of Knowledge and 20 from the Cochrane Library. A total of 415 articles were identified after deleting duplicates. The abstracts and full texts were retrieved and 397 articles were excluded according to the exclusion criteria. A further two articles were excluded because they reported the results of a previous study. This meant that 16 articles met the inclusion criteria 2,16 30 and they included 553 surgically-treated patients. The characteristics of the studies are presented in Table 1. The follow-up duration in the included studies ranged from 2.0 to 13.4 years, the mean follow-up in most studies being < 5 years. The data quality of the included studies was not high; according to the MJS, the randomized controlled study by Ploumis et al. 29 was the only one of high quality, the 15 2,16 nonrandomized studies 28,30 were low quality according to their MINORS scores. The ODI was used as a measure of functional improvement in nine studies, 2,21 24,26,27,29,30 including data from 321 patients (Table 2). The mean ODI score at final follow-up was 36.0 ± 7.8 (304 patients 2,21,23,24,26,27,29,30 ) and the mean decrease in ODI score (from preoperative to final follow-up) was 23.3 ± 11.3 (302 patients 2,21,22,24,26,27,29,30 ). Pre- and postoperative Cobb angles were 2,17 reported in 14 studies 21,23 30 which included data from 527 patients. The range of mean Cobb angle in these studies was preoperatively and at final follow-up. Overall, the mean Cobb angle was 26.7 ± 10.6 preoperatively and 13.3 ± 7.0 at final follow-up. The mean decrease in Cobb angle from preoperative to final follow-up was 13.5 ± 10.1 and the mean curve reduction as a percentage of the original curve was 48.5 ± 21.0%. Incidences of surgical complications and repeat surgery were reported in 14 studies. 2,16,17,20 22,24 30 The overall complication rate was 49.0% (171 compli - cations in 349 patients) from 12 studies. 2,16,17,20 22,24 26, There were 61 incidences of repeat surgery in 398 patients (15.3%) from 12 studies. 2,16,17,20,22 28,30 Discussion Although surgery is a treatment option for DS, controversy exists about its use. This systematic review demonstrated that, despite a high rate of complications and repeat procedures, surgery is an effective and 401

4 TABLE 1: Characteristics of the 16 studies included in the systematic review of surgery for the treatment of degenerative scoliosis, arranged in chronological order of publication date2,16 30 Level of MJS/MINORS Study No. of patients Study design evidence a score Marchesi et al., Retrospective III 10 b Grubb et al., Retrospective IV 12 b Iizuka and Yamada, Retrospective III 8 b Cho et al., Retrospective III 10 b Pateder et al., Retrospective III 8 b Berven et al., Retrospective IV 8 b Wu et al., Retrospective III 8 b Glassman et al., Prospective III 11 b Kluba et al., Retrospective II 9 b Crandall and Revella, Prospective IV 12 c Khan et al., Retrospective III 9 b Di Silvestre et al., Retrospective IV 8 b Transfeldt et al., Retrospective III 10 c Ploumis et al., Prospective I 7 d Keorochana et al., Prospective IV 9 b Li et al., Retrospective IV 8 b a Level of evidence indicates data quality classified from class I strongest evidence based on randomized controlled trials to class V the weakest (expert opinion). 13 b The scores of nonrandomized and noncomparative studies according to MINORS. 15 c The scores of nonrandomized and comparative studies according to MINORS. 15 d The scores of randomized controlled trials according to MJS. 14 MJS, modified Jadad scale 14 ; MINORS, methodological index for nonrandomized studies. 15 reasonable treatment for DS, providing improvement in ODI and in deformity correction as measured using the Cobb angle. The ODI is a valid and rigorous functional measure used for assessing spinal disorders. 12 The mean decrease in ODI of 23.3 points 2,21,22,24,26,27,29,30 suggests significant functional improvement in these patients. Taken together with the mean ODI at final follow-up of 36.0 (moderate disability), 2,21,23,24,26,27,29,30 these data suggest that surgery is an effective and reasonable treatment option for DS. Deformity correction, as measured by the Cobb angle, is another criterion for measuring the efficacy of surgery for DS. Patients in the current analysis gained considerable curve correction after surgery, providing further evidence that surgery is an effective treatment for DS. Complications and repeat operations undermine the value of surgery for DS, 31 and the incidence of surgical complications has been reported to be high (> 50%). 2,17,24,32 The overall rate of complications was 49.0% in the present analysis, 2,16,17,20 22,24 26,28 30 which is similar to the findings of others where the complication rate was 41% for patients aged years and 64% for those aged years. 33 The rate of repeat surgery was 15.3% in the present analysis, which is similar to published rates. 34,35 The rate of complications and repeat surgery was generally high and this must be taken into account when deciding to proceed with surgery. This systematic review had several limitations. First, the heterogeneity between 402

5 TABLE 2: Summary of the surgical outcomes of patients with degenerative scoliosis from the 16 studies included in the systematic review of surgery for the treatment of degenerative scoliosis, arranged in chronological order of publication date 2,16 30 Major Major curve curve No. of No. of Age Follow-up ODI reduction reduction No. of repeat Study patients (years) (years) ODI reduction ( ) (%) complications surgeries Marchesi et al., ( ) a a a a 7 1 Grubb et al., ( ) a a Iizuka and Yamada, ( ) b b a a Cho et al., ( ) Pateder et al., c 4.4 ( a ) a a c a Berven et al., ( ) b b Wu et al., ( ) a Glassman et al., ( a ) a 20.6 a a 7 2 Kluba et al., ( ) 42.0 a a 6 Crandall and Revella, ( ) Khan et al., ( ) c c Di Silvestre et al., ( ) Transfeldt et al., ( ) c 17 Ploumis et al., ( a ) a Keorochana et al., ( ) Li et al., ( ) b b Data presented as number of patients, means, or mean (range) or percentage as appropriate. a Data were not mentioned in the study. b Data were not presented in or could not be transformed into the forms used in this review. c Data could not be extracted or calculated. ODI, Oswestry Disability Index

6 individual studies was substantial because the indications for surgery, surgical procedures and outcome measures varied among the studies. Secondly, only one study 24 reported the data for pelvic incidence, and two studies 2,25 reported the data for coronal and sagittal imbalance. As restoration of sagittal balance is an important aspect that correlates with clinical improvement, 25,36 a lack of these data introduced another limitation. Thirdly, the data quality of the included studies was not high. Finally, there may have been some selection bias because the included series were confined to limited search terms and databases. In conclusion, despite a high rate of complications and repeat surgery, this systematic review demonstrates that surgery is an effective and reasonable treatment intervention for DS, providing an improvement in ODI and in deformity correction as measured using the Cobb angle. Standardizing both the indications for surgery and methodology for measuring changes in function and deformity correction should enhance the comparability and validity of future studies on this subject. In addition, analysis of sagittal and coronal balance should be regularly performed. Large scale, high quality studies with long term follow-up are needed to provide reliable evidence for future evaluation. Acknowledgements This study was partly supported by grants from the Science and Technology Planning Project of Zhejiang Province (2009C33093) and the National Nature Science Foundation of China ( ). Conflicts of interest The authors had no conflicts of interest to declare in relation to this article. Received for publication 26 November 2011 Accepted subject to revision 28 November 2011 Revised accepted 14 March 2012 Copyright 2012 Field House Publishing LLP References 1 Aebi M: Correction of degenerative scoliosis of the lumbar spine. A preliminary report. Clin Orthop Relat Res 1988; 232: Cho KJ, Suk SI, Park SR, et al: Complications in posterior fusion and instrumentation for degenerative lumbar scoliosis. Spine (Phila Pa 1976) 2007; 32: Ploumis A, Transfledt EE, Denis F: Degenerative lumbar scoliosis associated with spinal stenosis. Spine J 2007; 7: Vanderpool DW, James JI, Wynne-Davies R: Scoliosis in the elderly. J Bone Joint Surg Am 1969; 51: Aebi M: The adult scoliosis. Eur Spine J 2005; 14: Everett CR, Patel RK: A systematic literature review of nonsurgical treatment in adult scoliosis. Spine (Phila Pa 1976) 2007; 32 (19 suppl): S130 S Daffner SD, Vaccaro AR: Adult degenerative lumbar scoliosis. Am J Orthop (Belle Mead NJ) 2003; 32: Oskouian RJ Jr, Shaffrey CI: Degenerative lumbar scoliosis. Neurosurg Clin N Am 2006; 17: Bradford DS, Tay BK, Hu SS: Adult scoliosis: surgical indications, operative management, complications, and outcomes. Spine (Phila Pa 1976) 1999; 24: Prommahachai A, Wittayapirot K, Jirarattanaphochai K, et al: Correction with instrumented fusion versus non-corrective surgery for degenerative lumbar scoliosis: a systematic review. J Med Assoc Thai 2010; 93: Yadla S, Maltenfort MG, Ratliff JK, et al: Adult scoliosis surgery outcomes: a systematic review. Neurosurg Focus 2010; 28: E3. 12 Fairbank JC, Pynsent PB: The Oswestry Disability Index. Spine (Phila Pa 1976) 2000; 25: Wright JG, Swiontkowski MF, Heckman JD: Introducing levels of evidence to the journal. J Bone Joint Surg Am 2003; 85-A: Oremus M, Wolfson C, Perrault A, et al: Interrater reliability of the modified Jadad quality scale for systematic reviews of Alzheimer s disease drug trials. Dement Geriatr Cogn Disord 2001; 12:

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