this retrospective study included patients who had undergone ct between january 1st 2009 and december 31st 2009 . patients who met the following criteria were selected : over the age of 20 years , provided informed consent and underwent ct examinations to assess abdominal or urological lesion for reasons unrelated to lbp . all the ct scans ordered from the departments of general surgery and urology were included , and the ct scans which had been checked for a lbp evaluation from any related department , such as orthopaedic surgery , neurologic surgery , and rehabilitation , were excluded . to prevent result bias , a total of 855 participants , aged from 20 to 86 years , were enrolled consecutively and assessed for the association between the ct - observed spondylolytic characteristics of the lumbosacral spine and lbp . the patients were grouped into 5 groups according to age ( group 1 , below 39 years ; group 2 , 40 to 49 years ; group 3 , 50 to 59 years ; group 4 , 60 to 69 years ; and group 5 , above 70 years ) . all participants , who had undergone multidetector ct scanning , were asked to complete the modified nordic low back pain questionnaire,5 ) which was administered by senior trained nurses . the first question on the questionnaire that was translated into korean was : " have you suffered low back pain almost every day for at least 1 month over the last 12 months ? " the individuals ' answers of " yes " or " no " to the above question were used in this study as the back pain outcome . similar methods have been used by several authors6,7 ) for work - related compensation assessments . ct was performed on one of three 16-multidetector computed tomography ( mdct ) machines or a dual source 64-mdct system ( lightspeed ultra , ge , milwaukee , wi , usa ) . because the images were obtained from patients with different indications and using different protocols , the axial slice thickness was varied from 0.75 mm to 5 mm . all the ct scans were analyzed in a blinded manner with respect to the clinical and personal data . all the ct scans were reviewed by two orthopedic surgeons ( sbk , an orthopedic spine surgeon with 8 years experience , and brh , a certified orthopedic surgeon with 1 year experience ) . the images were reviewed on a secure - access picture - archiving communication system ( pacs ; philips spectra , eindhoven , the netherlands ) . all examinations were evaluated to determine the existence of linear lucidity or a defect extending through the pars interarticularis in the lower lumbar spine and whether the defect was unilateral or bilateral . the prevalence of spondylolysis in the 5 different age groups and according to gender was calculated . multiple logistic regression analysis was used to examine the association between lbp and spondylolysis while adjusting for gender and age . the prevalence of those studied conditions in the subjects with and without lbp was also compared . this retrospective study included patients who had undergone ct between january 1st 2009 and december 31st 2009 . patients who met the following criteria were selected : over the age of 20 years , provided informed consent and underwent ct examinations to assess abdominal or urological lesion for reasons unrelated to lbp . all the ct scans ordered from the departments of general surgery and urology were included , and the ct scans which had been checked for a lbp evaluation from any related department , such as orthopaedic surgery , neurologic surgery , and rehabilitation , were excluded . to prevent result bias , a total of 855 participants , aged from 20 to 86 years , were enrolled consecutively and assessed for the association between the ct - observed spondylolytic characteristics of the lumbosacral spine and lbp . the patients were grouped into 5 groups according to age ( group 1 , below 39 years ; group 2 , 40 to 49 years ; group 3 , 50 to 59 years ; group 4 , 60 to 69 years ; and group 5 , above 70 years ) . all participants , who had undergone multidetector ct scanning , were asked to complete the modified nordic low back pain questionnaire,5 ) which was administered by senior trained nurses . the first question on the questionnaire that was translated into korean was : " have you suffered low back pain almost every day for at least 1 month over the last 12 months ? " the individuals ' answers of " yes " or " no " to the above question were used in this study as the back pain outcome . similar methods have been used by several authors6,7 ) for work - related compensation assessments . ct was performed on one of three 16-multidetector computed tomography ( mdct ) machines or a dual source 64-mdct system ( lightspeed ultra , ge , milwaukee , wi , usa ) . because the images were obtained from patients with different indications and using different protocols , the axial slice thickness was varied from 0.75 mm to 5 mm . all the ct scans were analyzed in a blinded manner with respect to the clinical and personal data . all the ct scans were reviewed by two orthopedic surgeons ( sbk , an orthopedic spine surgeon with 8 years experience , and brh , a certified orthopedic surgeon with 1 year experience ) . the images were reviewed on a secure - access picture - archiving communication system ( pacs ; philips spectra , eindhoven , the netherlands ) . all examinations were evaluated to determine the existence of linear lucidity or a defect extending through the pars interarticularis in the lower lumbar spine and whether the defect was unilateral or bilateral . the prevalence of spondylolysis in the 5 different age groups and according to gender was calculated . multiple logistic regression analysis was used to examine the association between lbp and spondylolysis while adjusting for gender and age . the prevalence of those studied conditions in the subjects with and without lbp was also compared . the 855 subjects included 551 men ( 64% ) and 304 women ( 36% ) . the mean age was 58.98  13.30 years ( range , 20 to 86 years ) . tables 1 and 2 provide further details of the demographic characteristics of the subjects and detailed descriptive statistical data of this study , respectively . within this population , 311 patients ( 36% ) had lbp . among the populations presenting with lbp , 179 ( 21% ) subjects men demonstrated a significant greater presence of lbp than women ( p = 0.001 ) . out of 78 spondylolysis patients ( 9% ) , 51 ( 65% ) were male and 27 ( 35% ) were female . men demonstrated a significantly higher prevalence of spondylolysis ( p = 0.033 ) but this difference was not significant due to the selected population bias . the prevalence of spondylolysis was similar in the age groups ( p = 0.177 ) . fifty one patients ( 6% of the study population and 65% of the spondylolysis population ) demonstrated bilateral spondylolysis and 27 patients ( 3% of the study population and 35% of the spondylolysis population ) demonstrated unilateral spondylolysis . seventy eight patients ( 9% of the study population ) demonstrated lumbar spondylolysis on the ct findings . within this spondylolysis population , 33 patients ( 42% ) had back pain and 45 patients ( 58% ) did not . table 6 compares the prevalence of spondylolysis in the groups of individuals with and without lbp . table 6 lists the results of multiple logistic regression analysis where lbp was a dependent variable and the presence of spondylolysis in the different gender and age groups was included as an independent variable . there were no significant associations found between spondylolysis and the aforementioned predicting variables ( p > 0.05 for each association ) . within this population , 311 patients ( 36% ) had lbp . among the populations presenting with lbp , 179 ( 21% ) subjects were male and 132 ( 15% ) subjects were female . men demonstrated a significant greater presence of lbp than women ( p = 0.001 ) . out of 78 spondylolysis patients ( 9% ) , 51 ( 65% ) were male and 27 ( 35% ) were female . men demonstrated a significantly higher prevalence of spondylolysis ( p = 0.033 ) but this difference was not significant due to the selected population bias . the prevalence of spondylolysis was similar in the age groups ( p = 0.177 ) . fifty one patients ( 6% of the study population and 65% of the spondylolysis population ) demonstrated bilateral spondylolysis and 27 patients ( 3% of the study population and 35% of the spondylolysis population ) demonstrated unilateral spondylolysis . seventy eight patients ( 9% of the study population ) demonstrated lumbar spondylolysis on the ct findings . within this spondylolysis population , 33 patients ( 42% ) had back pain and 45 patients ( 58% ) did not . table 6 compares the prevalence of spondylolysis in the groups of individuals with and without lbp . table 6 lists the results of multiple logistic regression analysis where lbp was a dependent variable and the presence of spondylolysis in the different gender and age groups was included as an independent variable . there were no significant associations found between spondylolysis and the aforementioned predicting variables ( p > 0.05 for each association ) . there are few reports that have focused on the incidence of spondylolysis in asian populations , such as japanese and koreans , the reports that are available have some weaknesses . one is that the subjects of the investigation were not part of the general population but were lbp patients . another weakness lies in the methods used in the analysis , such as plain radiographs or skeletal investigation . despite these potential pitfalls such as the representative korean population in this study , the strength of this study is that a selected community sample was included , multidetector ct scans were used to detect spondylolysis and the younger age group ( below 20 years old ) was excluded . hu et al.1 ) reported that the prevalence of a defect in the pars interarticularis was approximately 5% in the general population . some authors8 - 10 ) reported that the prevalence of spondylolysis was 6% in adults . the previous large screening study of virta et al.,10 ) which is often cited , was based only on plain radiographs . for example , the native american and eskimo population has a very high incidence of spondylolysis , ranging from 17% to 53%9 ) and the prevalence of spondylolysis in the caucasian population is two to three times higher than that in the african population.8,9 ) kalichman et al.9 ) reported that the prevalence of lumbar spondylolysis in an unselected community - based population is 11.5% , which is almost twice the prevalence of the previous plain radiograph - based studies . similar to this study , a likely explanation for the significantly higher rate identified in the current study is the use of ct . ct is a highly advanced imaging modality and is considered the gold standard for identifying spondylolysis , particularly the unilateral and non - displaced bilateral cases . sakai et al.,11 ) who used ct imaging on 2000 subjects , reported a 5.9% incidence of spondylolysis in a japanese population . the incidence of spondylolysis of this study was 9.12% , which is similar to kalichman et al.9 ) but much higher than sakai et al.11 ) in terms of the epidemiologic patterns , there was no significant difference in the prevalence of spondylolysis between men and women . however , the male - to - female ratio was almost 2:1 in previous studies.1,11 - 13 ) waldron14 ) suggested in 1991 that the difference in incidence between genders may be a rather recent phenomenon . , no significant associations were found between spondylolysis and the presence of lbp ( p = 0.402 ) . the relationship between spondylolysis and the occurrence of lbp is controversial.8,15 ) a recent study by miyauchi et al.16 ) reported that spondylolysis appeared as pseudoarthrosis , and there was no histological correlation with chronic lbp . individuals engaged in specific athletic activities appeared more likely to develop symptomatic lbp associated with spondylolysis.17 ) the pathologic mobility of the " gill fragment " of the spinal lamina is considered to be a lbp source but in many cases , spondylolysis is found incidentally in the asymptomatic general population.8,15 ) no significant associations were found between spondylolysis and adult age . hu et al.1 ) stated that the prevalence of spondylolysis was 4.4% at six years of age and 6% in adulthood . eisenstein18 ) reported that only 1 of the 485 skeletons he examined had unilateral spondylolysis . sakai et al.11 ) showed that the ratio of unilateral spondylolysis to bilateral spondylolysis is 21.0% . however , in our study , 27 of a total 78 spondylolytic subjects ( 34.6% ) had unilateral spondylolysis . it is not possible to conclude that the ratio of unilateral spondylolysis to all spondylolysis is more frequent in koreans according to the current data . in addition , the displacement of spondylolysis was not evaluated on a ct axial image of abdomen or pelvis . hence , the relationship between lbp and the displacement of spondylolysis also was not known . in conclusion , the incidence of lumbar spondylolysis in the 855 adults in this study was 78 subjects , i.e. , 9% ( males , 6% ; females , 3% ) . no significant association was found between the presence of spondylolysis on ct and the occurrence of lbp . this suggests that the condition does not represent a major cause of lbp in the general population .
backgroundto determine the prevalence of spondylolysis in a selected population and evaluate the association of spondylolysis with low back pain ( lbp ) . 
 spondylolysis is widespread in the general population but the prevalence of spondylolysis and its relationship with lbp in the korean population is controversial.methodsa sample of 855 participants ( age , 20 to 86 years ) from our medical center who underwent multidetector computed tomography ( ct ) imaging to assess abdominal and urological lesions were enrolled in this study . 
 the occurrence of lbp requiring medication in the preceding 12 months was evaluated using a self - report questionnaire ( a modified nordic low back pain questionnaire ) . 
 the presence of spondylolysis was characterized by ct imaging . 
 multiple logistic regression models were used to examine the association between spondylolysis and lbp , while adjusting for gender and age.resultsseventy-eight study subjects ( 9% ) demonstrated spondylolysis on ct imaging . 
 there was no significant difference between the age groups ( p = 0.177 ) . 
 the p - value of gender was 0.033 but this was not significant due to the selected population bias . 
 three hundred eleven study subjects ( 36% ) had back pain . 
 there was a significant difference between gender ( p = 0.001 ) . 
 no significant association was identified between spondylolysis and the occurrence of lbp.conclusionsthe prevalence of lbp was 36.37% and the prevalence of lumbar spondylolysis in a selected population , who visited hospital for abdominal or urological lesions except lbp , was 9.12% based on ct imaging . 
 males demonstrated a similar presence of lbp to females but a significantly higher incidence of spondylolysis ( p = 0.033 ) . 
 the prevalence of spondylolysis was not associated with the presence of lbp and age in adulthood .