Background: Studies on adolescent idiopathic scoliosis have well documented the differences between natural history of male and female patients. There are also differences in responses to nonoperative treatment, but the results of operative treatment in male patients compared with females have not been widely reported. Only few studies had compared the outcomes of operative treatment between male and female patients with different results. Methods: We retrospectively reviewed the outcome of 150 (112 girls and 38 boys) consecutive patients with diagnosis of adolescent idiopathic scoliosis who were managed surgically between May 1996 and September 2005. Next, male radiographic parameters were compared with female ones pre- and postoperatively. Then, a subgroup of 38 matched girls was compared regarding the age, curve type, curve magnitude, and the instrumentation we used. Results: In comparing male patients with unmatched girls, the boys had greater mean age (17.3 Â± 2.3 vs. 16.3 Â± 2.9; p = 0.049), greater primary curve (71.4 Â± 21.3Â° vs. 62.7 Â± 17.5Â°; p = 0.013), less flexibility (30.1 Â± 13.5 vs. 40.3 Â± 17.8; p = 0.01), and less correction percentage (51.3 Â± 12.9 vs. 58.8 Â± 16.5; p = 0/013). The loss of correction was comparable between the two groups. In the matched comparison, the flexibility in boys was less than girls (30.1 Â± 13.5 vs. 38.1 Â± 17.5; p = 0.027). Also, the boys had a smaller correction percentage compared to the girls, but this finding was not statistically significant. Conclusion: There was similar distribution curve pattern between male and female patients with AIS. Males had more rigid primary curves compared to females but a similar degree of postoperative scoliosis correction. Male AIS patients were older at the time of surgery. These preoperative gender differences, however; did not compromise the radiological outcomes of surgical treatment and the results were comparable between the genders. Â© 2008 Ameri et al; licensee BioMed Central Ltd

Ameri, E.

Behtash, H.

Mobini, B.

Momeni, B.

Omidi-Kashani, F.

eprints Iran University of Medical Sciences

BioMed CentralScoliosisssOpen AcceResearchRadiographic outcome of surgical treatment of adolescent idiopathic scoliosis in males versus femalesEbrahim Ameri1, Hamid Behtash1, Bahram Mobini1, Farzad Omidi-Kashani*1 and Behnam Momeni2Address: 1Department of Spine Surgery, Shafa Yahyaiian Hospital, Iran University of Medical Sciences, Tehran, Iran and 2Department of Orthopedic Surgery, Shafa Yahyaiian Hospital, Iran University of Medical Sciences, Tehran, IranEmail: Ebrahim Ameri - ebrahim.ameri@yahoo.com; Hamid Behtash - hbehtash@yahoo.com; Bahram Mobini - bmobini@hotmail.com; Farzad Omidi-Kashani* - omidif@mums.ac.ir; Behnam Momeni - bmomeni@yahoo.com* Corresponding author    AbstractBackground: Studies on adolescent idiopathic scoliosis have well documented the differencesbetween natural history of male and female patients. There are also differences in responses tononoperative treatment, but the results of operative treatment in male patients compared withfemales have not been widely reported. Only few studies had compared the outcomes of operativetreatment between male and female patients with different results.Methods: We retrospectively reviewed the outcome of 150 (112 girls and 38 boys) consecutivepatients with diagnosis of adolescent idiopathic scoliosis who were managed surgically betweenMay 1996 and September 2005. Next, male radiographic parameters were compared with femaleones pre- and postoperatively. Then, a subgroup of 38 matched girls was compared regarding theage, curve type, curve magnitude, and the instrumentation we used.Results: In comparing male patients with unmatched girls, the boys had greater mean age (17.3 ±2.3 vs. 16.3 ± 2.9; p = 0.049), greater primary curve (71.4 ± 21.3° vs. 62.7 ± 17.5°; p = 0.013), lessflexibility (30.1 ± 13.5% vs. 40.3 ± 17.8%; p = 0.01), and less correction percentage (51.3 ± 12.9%vs. 58.8 ± 16.5%; p = 0/013). The loss of correction was comparable between the two groups. Inthe matched comparison, the flexibility in boys was less than girls (30.1 ± 13.5% vs. 38.1 ± 17.5%;p = 0.027). Also, the boys had a smaller correction percentage compared to the girls, but thisfinding was not statistically significant.Conclusion: There was similar distribution curve pattern between male and female patients withAIS. Males had more rigid primary curves compared to females but a similar degree ofpostoperative scoliosis correction. Male AIS patients were older at the time of surgery. Thesepreoperative gender differences, however; did not compromise the radiological outcomes ofsurgical treatment and the results were comparable between the genders.BackgroundAdolescent idiopathic scoliosis (AIS) is a structural three-dimensional deformity of the spine that occurs at or nearthe onset of puberty for which no cause can be estab-Published: 6 September 2008Scoliosis 2008, 3:12 doi:10.1186/1748-7161-3-12Received: 14 July 2008Accepted: 6 September 2008This article is available from: http://www.scoliosisjournal.com/content/3/1/12© 2008 Ameri et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Page 1 of 5(page number not for citation purposes)Scoliosis 2008, 3:12 http://www.scoliosisjournal.com/content/3/1/12lished. In patients with small curve magnitude in themean of 10° or so, the male and female prevalence isapproximately equal. In curves of larger magnitude, how-ever, there is an overwhelming female predominance in away that the ratio of females to males with curves measur-ing 30° or more is 10 to 1 [1,2].According to epidemiologic and natural history studies,curve progression is different in male and female patients.Studies conducted by Suh and MacEwen [3], and Karol etal [4] on curve behavior in males verified that scolioticmale patients demonstrated clinically significant curveprogression until Risser V. In females, scoliosis beyondRisser IV can be considered as an adult curve; Scoliosis inmales, however, can be evaluated as an adult curve only atRisser V.Bracing has been shown to effectively prevent curve pro-gression in adolescent girls [5], but it is not always effec-tive for the males [6,7]. Karol reported the result ofbracing in 112 boys with AIS. 74% of these boys pro-gressed by more than 6°, which is more than failure rateof bracing in girls. Moreover, the amount of curve correc-tion among male patients in brace is lower compared togirls'. It has also been suggested that the spine is stiffer inmales than in females [6].Despite the importance of gender difference in curvebehavior and the results of brace treatment, there are alimited number of studies comparing the results of surgi-cal treatment between males and females. Thus, the pur-pose of this study was to compare the radiographicoutcome of surgery for AIS between males and females inmatched and unmatched groups in regard to age, curvetype, and magnitude.MethodsMethodologically, a retrospective review of the records ofall patients who had been surgically treated for AISbetween May 1996 and September 2005 at our hospitalwas performed at first. 18 patients were treated with Har-ington instrumentation and 132 patients with modernsegmental spinal instrumentation (Cotrel-Dubousset;CD: 24, Diapason: 103, and Universal Spine System; USS:5 cases). The patients who were treated by only anteriorsurgery were excluded. Radiographic measurement wereperformed on standing posteroanterior and lateral radio-graphs of the total spine (T1-S1) acquired before surgery,at 4 days, 6 weeks, 6 months, 1, and 2 years respectivelyafter surgery and at final follow-up. The Cobb method wasused to measure the curve magnitude [8].At the next step, preoperative coronal curve flexibilitymeasurements from the right and left supine side bendingradiographs were acquired. These views were all takenwhile the patients actively bent laterally (Figure 1). Inorder to calculate the percentage of flexibility, we sub-tracted the magnitude of the bend Cobb angle from themagnitude of the preoperative upright coronal Cobbangle and then divided it by the preoperative uprightcoronal Cobb angle calculated the percentage of flexibil-ity. For calculating postoperative percent correction of thecoronal curves, we Subtracted the magnitude of the coro-nal Cobb angle at final follow-up from the preoperativecoronal Cobb angle and then divided it by the preopera-tive Cobb angle calculated postoperative percent correc-tion of the coronal curves. The King classification wasused to categorize the curve types [9].Our threshold level for doing only PSF (posterior spinalfusion) or combined ASF (anterior spinal fusion) and PSFwas a curve magnitude of 70°. We used bending viewsmostly for determining the fusion levels. In anterior sur-gery, we released the most rigid segment of the spine andthen inserted autogenous (in the thoracic area and fromthe harvested rib) or allogenous (in the lumbar area) typeof cancellous bone graft in the intervertebral spaces with-A 15 years old boy presented with AISFigure 1A 15 years old boy presented with AIS. Above: preop-erative standing posteroanterior and lateral views, below: supine left and right bending films.Page 2 of 5(page number not for citation purposes)Scoliosis 2008, 3:12 http://www.scoliosisjournal.com/content/3/1/12out implanting the spine. PSF and instrumentation withor without anterior surgery were conducted in all patients.These combined procedures were done in separate sec-tions with the interval of 5 to 7 days. The details of thetypes of instrumentation used for our operative techniquehave been reported previously [10]. The USS wasimplanted according to the manufacturer's instructions[11]. PSF included decortication of the laminae, facetjoint cleaning, and use of local bone graft besides anautograft from the posterior iliac crest (Figure 2).The comparison between male and female patients wasdone in two stages. At first, all of the males were comparedwith all of the females. In the second stage, each malepatient was matched with a female based on the factorssuch as age (± 1 year), curve type (according to the Kingclassification), curve magnitude (± 5), and instrumenta-tion used so that the final study series comprised 38matched pairs.Statistical analysis was performed by the x2 test or theMann-Whitney test. P value equal to or below 0.05 wasconsidered statistically significant.ResultsThis analysis includes the data for 150 patients (112females; 74.7% and 38 males; 25.3%). All patients hadclinical and radiographic follow-up of at least 2 years. Themean age of the males at the time of operation was 17.3 ±2.2 years and that of the females 16.3 ± 2.8 years (p =0.049; significant). The mean follow-up time was 3.6years (range 2.3 – 10.2 years).The King classification distribution between the two gen-der is listed in table 1. There is similar distribution curvepattern between male and female, with King type III mak-ing up 47.4% and 47.3% of all the curve types for malesand females, respectively.We performed PSF alone on 11 males (28.9%) and 58females (51.8%). ASF and then PSF with instrumentationwere conducted on the rest. Harrington rod was used in 4(10.5%) male and 14 (12.5%) female patients and seg-mental spinal instrumentation in other cases.At first, in comparing all male patients with all females,the males had greater mean age and primary curve magni-tude, but less flexibility and correction percentage thatwere statistically significant. Loss of correction was com-parable between the two groups (table 2).In the second stage of the study, the 38 male patients werecompared with the 38 matched females to determinewhether gender difference had an effect on the operativeresults (table 3). In this comparison, flexibility percentwas the only index that had a statistically significant dif-ference (the boys had more rigid curves). The correctionpercentage and loss of correction in boys were less thangirls but these were not statistically significant (p = 0.11and 0.25 respectively). We performed only PSF in 13 and11 female and male patients in this group respectively. Inother cases, ASF and then PSF with instrumentation wereconducted. Therefore, the difference in prevalence of thetype of surgery in matched group was not statistically sig-nificant, (p > 0.05).DiscussionIn the initial reports of segmental spinal instrumentationin the treatment of AIS, some radiographic distinctionsPostoperative radiographs of the patient on Figure 1Figure 2Postoperative radiographs of the patient on Figure 1. Posteroanterior and lateral standing views 5 years after sur-gery. The patient was completely asymptomatic at the latest follow-up visit.Table 1: Curve pattern according to King classificationKing Classification Male (%) Female (%)I 6 (11) 11 (9.8)II 9 (23.7) 32 (28.6)III 18 (47.4) 53 (47.3)IV 2 (5.2) 9 (8)V 3 (7.9) 7 (6.3)Page 3 of 5(page number not for citation purposes)Scoliosis 2008, 3:12 http://www.scoliosisjournal.com/content/3/1/12between boys and girls had been reported [12,13].According to these reports, between 10% and 30% ofpatients requiring operative intervention for AIS are males[3,14]. We found a similar percentage in our study (i.e., of150 operative patients in this series, 25.3% were male).A comparison of the surgical treatment outcomes in bothgenders has only been reported from few investigations[15-17]. We found that preoperative curve patternbetween the genders are roughly similar in King classifica-tion distribution. However, the older male patients hadbigger curve magnitude, and less preoperative primarycurve flexibility than female patients. This observationcontradicts what has been previously reported by Sucatoet al [15]. They found larger primary male curves withsimilar curve stiffness in their comparison of male-femalepatients.Marks et al. in a study of 547 (449 females and 98 males)patients, found that male AIS patients had more rigid pri-mary curve compared to females but showed a similardegree of postoperative scoliosis correction [16]. Theyconcluded that differences in the preoperative status andperioperative course did not compromise the outcomes ofsurgical treatment as in all other measures; moreover, theresults were comparable between the genders.Regardless of the preoperative differences and slight vari-ation in treatment approaches, our study revealed thatsurgical outcomes are comparable between the genders.Primary curve percent correction and loss of correctionover time were not statistically different between the gen-ders.According to our knowledge, there are only two matchedstudies of the surgical treatment of AIS between male andfemale patients:In the first, Helenius and coauthors compared the resultsof operative treatment of 30 male and female AIS pairs.They finally concluded that the curves in males appear tobe more rigid than in females; however, posterior surgeryfor AIS provides similar short and long-term results inboth genders [17].The second study that was conducted by Sucato et al. [15],revealed that treatment outcome differences did exist.They reported less correction of the curve in males com-pared to females. In an attempt to explain this finding,they theorized that perhaps the male patients produce amore powerful supine bend effort, reflected by a greaterpreoperative flexibility that the surgeon cannot duplicateat the time of surgery. Our findings about preoperativestiffer curves in males yet equal curve correction betweenthe genders after surgery discredit this theory.ConclusionIn conclusion, male patients with AIS have the similarcurve pattern as that of female patients. Males had morerigid primary curves compared to females but a similardegree of postoperative scoliosis correction. Male AISpatients were older at the time of surgery. These preoper-ative gender differences, however; did not compromisethe radiological outcomes of surgical treatment and theresults were comparable between the genders.Competing interestsThe authors declare that they have no competing interests.Authors' contributionsEA, the senior surgeon and has made substantial contribu-tions to conception and design of the manuscript. HB hasbeen involved in drafting the manuscript, participated inTable 2: The results of the comparison all males with all femalesMales Females P valuePreoperativeAge (year) 17.3 ± 2.3* 16.3 ± 2.9 0.049Primary curve (°) 71.4 ± 21.3 62.7 ± 17.5 0.013Flexibility (%) 30.1 ± 13.5 40.3 ± 17.8 0.01PostoperativePrimary curve (°) 35.3 ± 16.4 26.6 ± 15.4 0.03Correction (%) 51.3 ± 12.9 58.8 ± 16.6 0.013Final visitPrimary curve (°) 37.6 ± 16.3 29.1 ± 15.6 0.04Loss of correction (°) 2.3 ± 1.9 2.6 ± 2.30.528 (NS)*Mean ± Standard Deviation NS: Not SignificantTable 3: The results of the comparison between males and matched femalesMales Females P valuePreoperativePrimary curve (°) 71.4 ± 21.3* 70.2 ± 18.50.79 (NS)Flexibility (%) 30.1 ± 13.5 38.1 ± 17.5 0.027PostoperativePrimary curve (°) 35.3 ± 16.3 31.6 ± 18.8 0.35 (NS)Correction (%) 51.3 ± 12.9 57.1 ± 18.2 0.11 (NS)Final visitPrimary curve (°) 37.6 ± 16.3 34.4 ± 18.9 0.35 (NS)Loss of correction (°) 2.3 ± 1.9 2.8 ± 2.2 0.25 (NS)* Mean ± Standard Deviation  NS: Not SignificantPage 4 of 5(page number not for citation purposes)Scoliosis 2008, 3:12 http://www.scoliosisjournal.com/content/3/1/12Publish with BioMed Central   and  every scientist can read your work free of charge"BioMed Central will be the most significant development for disseminating the results of biomedical research in our lifetime."Sir Paul Nurse, Cancer Research UKYour research papers will be:available free of charge to the entire biomedical communitypeer reviewed and published immediately upon acceptancecited in PubMed and archived on PubMed Central yours — you keep the copyrightSubmit your manuscript here:http://www.biomedcentral.com/info/publishing_adv.aspBioMedcentralthe sequence alignment. BaM has made substantial contri-butions to acquisition of data from literature. FOK holdsa spine fellowship. He is a junior surgeon and has hadsubstantial role in preparing and revising the manuscript.BeM is an orthopedic surgeon and very helpful in collect-ing the data. He has made important critical contributionsto manuscript revision in terms of its intellectual content.All authors read and approved the final manuscript.AcknowledgementsThe authors acknowledge the assistance of Mohamadian N in data manage-ment and statistical analysis.References1. Winiarski A, Zarzycki D, Koniarski A, Kalicinski M: The natural his-tory of idiopathic scoliosis.  Orthop Traumatol Rehabil 2005,7(1):1-7.2. Raggio CL: Sexual dimorphism in adolescent idiopathic scolio-sis.  Orthop Clin North Am 2006, 37(4):555-8.3. Suh PB, MacEwen GD: Idiopathic scoliosis in males. A naturalhistory study.  Spine 1988, 13(10):1091-5.4. Karol LA, Johnston CE, Browne RH, Madisone M: Progression ofthe curve in boys who have idiopathic scoliosis.  J Bone Joint SurgAm 1993, 75(12):1804-10.5. Lenssinck ML, Frijlink AC, Berger MY, Bierman-Zeinstra SM, VerkerkK, Verhagen AP: Effect of bracing and other conservative inter-ventions in the treatment of idiopathic scoliosis in adoles-cents: a systematic review of clinical trials.  Phys Ther 2005,85(12):1329-39.6. Karol LA: Effectiveness of bracing in male patients with idio-pathic scoliosis.  Spine 2001, 26(18):2001-5.7. Yrjonen T, Yilkoski M, Schlenzka D, Poussa M: Results of bracetreatment of adolescent idiopathic scoliosis in boys com-pared with girls: a retrospective study of 102 patientstreated with the Boston brace.  Eur Spine J 2007, 16(3):393-7.8. Cobb JR: Outline for the study of scoliosis.  Instr Course Lect AAOS1948, 5:261-75.9. King HA, Moe JH, Bradford DS, Winter RB: The selection of fusionlevels in thoracic idiopathic scoliosis.  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Sucato DJ, Hedequist D, Karol LA: Operative correction of ado-lescent idiopathic scoliosis in male patients. A radiographicand functional outcome comparison with female patients.  JBone Joint Surg Am 2004, 86(A):2005-14.16. Marks M, Petcharapom M, Betz RR, Clements D, Lenke L, NewtonPO: Outcomes of surgical treatment in male versus femaleadolescent idiopathic scoliosis patients.  Spine 2007,32(5):544-9.17. Helenius I, Remes V, Yrjonen T, Ylikoski M, Schlenzka D, Helenius M,Poussa M: Does gender affect outcome of surgery in adoles-cent idiopathic scoliosis?  Spine 2005, 30(4):462-7.Page 5 of 5(page number not for citation purposes)

Radiographic outcome of surgical treatment of adolescent idiopathic scoliosis in males versus females

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Radiographic outcome of surgical treatment of adolescent idiopathic scoliosis in males versus females

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