Spondylolysis, spondylolisthesis, and lumbo-sacral morphology in a medieval English skeletal population

Segmental vertebral three-dimensional motion in patients with L4 isthmic spondylolisthesis under weight-bearing conditions

OBJECTIVE

To investigate in vivo 6-degree-of-freedom (DOF) vertebral motion in patients with isthmic spondylolisthesis (IS) during various functional weight-bearing activities.

METHODS

Fifteen asymptomatic volunteers (mean age 54.8 years) and fourteen patients with IS at L4-5 (mean age 53.4 years) were recruited. The positions of the vertebrae (L4-L5) in the supine, standing, flexion-extension, left-right twisting and left-right bending positions were determined using previously described CT-based models and dual fluoroscopic imaging techniques. Local coordinate systems were established at the center of the anterior vertebra of L4 isthmic spondylolisthesis (AIS), the posterior lamina of L4 isthmic spondylolisthesis (PIS) and the center of the L5 vertebra to obtain the 6DOF range of motion (ROM) at L4-L5 and the range of motion (ROM) between the AIS and the PIS.

RESULTS

The translation along the anteroposterior axis at L4-L5 during flexion-extension, left-right bending and left-right twisting was significantly greater than that of the healthy participants. However, the translation along the mediolateral axis at L4-L5 presented paradoxical motion under different positions: the ROM increased in the supine-standing and flexion-extension positions but decreased in the left-right bending and left-right twisting positions. The separation along the anteroposterior axis during flexion was significantly greater than that during standing, on average, reaching more than 1 mm. The separation along the mediolateral axis during standing, flexion and extension was significantly greater than that in the supine position.

CONCLUSIONS

This study revealed the occurrence of displacement between the AIS and PIS, primarily in the form of separation during flexion. Symptomatic patients with isthmic spondylolisthesis exhibit intervertebral instability, which might be underestimated by flexion-extension radiographs.

Utility of ultrasonography in the diagnosis of lumbar spondylolysis in adolescent patients

BACKGROUND

This study aims to investigate the utility of the Doppler effect on ultrasonography for the diagnosis of very early- and early-stage lumbar spondylolysis in adolescent patients.

METHODS

In total, 76 adolescent patients with acute and subacute low back pain were prospectively enrolled, with 46 having lumbar spondylolysis and the remaining 30 having low back pain without spondylolysis. MRI and/or computed tomograms scans revealed very early- and early-stage lumbar spondylolysis. Furthermore, positive Doppler findings in ultrasonography around the area from the facet joint to the laminae were investigated.

RESULTS

There were no significant differences in age (p > 0.99) and body mass index (p = 0.11) between cases with and without spondylolysis. Very early- and early-stage spondylolysis were observed in 27.6% and 72.4% of patients, respectively. Positive power Doppler was 91.3% and 33.3% in cases with and without spondylolysis, respectively, which was significantly higher in spondylolysis (p < 0.001). The sensitivity and specificity of this positive power Doppler were 91.4% and 66.7%, respectively. Furthermore, the rate of positive power Doppler was significantly higher in early-stage spondylolysis (p = 0.02), with 75.0% and 97.6% sensitivity in very early- and early-stage spondylolysis, respectively.

CONCLUSIONS

A positive Doppler effect on ultrasonography is effective for screening very early- and early-stage spondylolysis in adolescent patients in an outpatient clinic.

Risk Factors for Symptomatic Bilateral Lumbar Bone Stress Injury in Adolescent Soccer Players: A Prospective Cohort Study

BACKGROUND

Lumbar bone stress injury (BSI) is a high-risk long time-loss injury for adolescent soccer players. However, the risk factors for lumbar BSI are unclear.

PURPOSE

To identify the risk factors for bilateral lumbar BSI for adolescent soccer players.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Adolescent soccer players underwent orthopaedic examination, whole-body dual energy x-ray scan, lumbar magnetic resonance imaging (MRI), and muscle tightness testing at baseline. Lumbar lordosis (LL), sacral slope, maturity stage of lumbar vertebral body, and bone marrow edema (BME) at the L5 were examined via MRI. In addition, bone mineral density and content; trunk lean body mass via dual energy x-ray scan; and bilateral muscle tightness including the iliopsoas, hamstrings, and quadriceps were measured. Lumbar BSI was diagnosed as positive bilateral BME and extension-based lumbar pain. All participants were examined twice, one at 6 months and one at 1 year, after the baseline examination. Multivariate logistic regression analysis was performed to identify the risk factors for bilateral lumbar BSI.

RESULTS

A total of 69 (26.3%) players were diagnosed with bilateral lumbar BSI. Asymptomatic BME (odds ratio [OR], 4.260; 95% CI, 2.153-8.431), apophyseal stage of the lumbar vertebral body (OR, 3.438; 95% CI, 1.698-6.959), sacral slope relative to LL ≥5° (OR, 4.067; 95% CI, 2.021-8.181), and hamstring tightness ≥50° (OR, 3.221; 95% CI, 1.385-7.489) were significantly associated with bilateral lumbar BSI.

CONCLUSION

The incidence of bilateral lumbar BSI was common at 26.2%. Asymptomatic BME, sacral anterior tilt relative to LL, immature lumbar epiphyses, and hamstring tightness were found to be risk factors for bilateral lumbar BSI. The results of this study suggest that regular MRI examination could facilitate the early detection of BME, and improvement in hamstring flexibility and lumbosacral alignment may prevent bilateral lumbar BSI in young athletes.

Sacral Spina Bifida Occulta: A Frequency Analysis of Secular Change

Substantial relaxation of natural selection beginning around 1900 changed the mutation/selec­tion balance of modern genetic material, producing an increase in variable anatomical structures. While multiple structures have been affected, the temporal increase in variations of the sacrum, specifically, ‘Sa­cral Spina Bifida Occulta,’ have been reliably demonstrated on a localised scale. Calculation of largescale frequency has been hindered by the localised nature of these publications, the morphological variability of this variation, and potential pathological associations, which have produced divergent classifications, and conflicting reported rates of occurrence. A systematic review of the reported literature was conducted to provide an objective analysis of Sacral Spina Bifida Occulta frequency from 2500 BCE to the present. This review was designed to compensate for observed inconsistencies in reporting and to ascertain, for the first time, the temporal trajectory of this secular trend. A systematic review of Sacral Spina Bifida Occulta lit­erature was conducted through the strict use of clinical meta-analysis criteria. Publications were retrieved from four databases: PubMed, Embase, the Adelaide University Library database, and Google Scholar. Data were separated into three historical groups, (1 = <1900, 2 = 1900 to 1980 and 3 = >1980), and frequency outcomes compared, to determine temporal rates of occurrence. A total of 39/409 publications were included in the final analysis, representing data for 16,167 sacra, spanning a period of 4,500 years. Statistically significant results were obtained, with total open S1 frequen­cy increasing from 2.34%, (79 to 1900CE), to 4.80%, (1900 to 1980CE) and to 5.43% (>1980CE). These increases were significant at p<0.0001, with Chi-squared analysis. A clear secular increase in the global frequency of Sacral Spina Bifida Occulta has been demonstrated from 1900 to the present. This research provides a novel and adaptable framework for the future assessment of variation distribution, with impor­tant implications for the fields of biological anthropology and bioarchaeology.

Is Increased Kicking Leg Iliopsoas Muscle Tightness a Predictive Factor for Developing Spondylolysis in Adolescent Male Soccer Players?

OBJECTIVE

To identify predictive risk factors of lumbar stress (LS) fracture developing from an asymptomatic stress reaction of the pedicle among adolescent male soccer players.

DESIGN

Prospective cohort study.

SETTING

Amateur Japanese adolescent male soccer team.

PARTICIPANTS

Japanese adolescent male soccer players (n = 195) aged 12 to 13 years.

ASSESSMENT OF RISK FACTORS INDEPENDENT VARIABLES

Height, body weight, body mass index, muscle tightness of both lower extremities (iliopsoas, hamstrings, and quadriceps), lumbar bone mineral content, developmental age, and lumbar lordosis angle were measured as baseline measurements.

MAIN OUTCOME MEASURES DEPENDENT VARIABLE

Players who were diagnosed with an asymptomatic stress reaction of the lumbar spine pedicle at baseline were followed; extension-based lumbar pain was defined 1 year after the baseline. The players were assigned to the LS fracture or control (CON) group at follow-up.

RESULTS

At baseline, 40 boys were diagnosed with an asymptomatic stress reaction of the lumbar spine pedicle. The difference in muscle tightness between the kicking leg and supporting leg was significantly different (P = 0.012) between the LS (n = 16) and CON (n = 22) groups. Increase in iliopsoas muscle tightness in the kicking leg was a predictive risk factor of developing extension-based lumbar pain after adjusting for developmental age and body mass index (odds ratio, 1.54; 95% confidence interval, 1.05-2.27).

CONCLUSIONS

Development of extension-based lumbar pain from an asymptomatic stress reaction of the pedicle among adolescent male soccer players was associated with increased iliopsoas muscle tightness of the kicking leg relative to that of the supporting leg.

Familial development of lumbar spondylolysis: a familial case report of 7- and 4-year-old brothers and their father

The incidence of lumbar spondylolysis is affected by sex, race, and congenital abnormalities. These differences suggest a genetic component to the etiology of spondylolysis. However, no definitive evidence has been presented regarding the inheritance of lumbar spondylolysis. We report familial cases of lumbar spondylolysis in 7- and 4-year-old brothers and their father, each of whom visited our clinic complaining of low back pain. Spondylolysis in the fifth lumbar vertebra (L5) was identified in both boys and their father from clinical, radiographic, computed tomographic, and magnetic resonance imaging examinations. Conservative treatment was provided for both boys. No bony union of any spondylolytic lesions was obtained, but they returned to sports activity without low back pain. Frequent development of spondylolysis, even at younger ages, in all male family members might indicate an underlying genetic etiology in lumbar spondylolysis, primarily in the form of autosomal dominant inheritance. However, information on patients and their parents should be considered carefully, as bony union with conservative therapy is not expected in such patients.

Sacral Anatomical Orientation in the Lebanese Population

INTRODUCTION

PI is currently used as the gold standard measurement in spinopelvic anatomy. There is a need for a reliable method to calculate sacral anatomic orientation (SAO) independent of posture and to establish its association with PI, which was previously established in a single study (Peleg et al., 2007). Therefore, the aim of our study is the application and verification of this association on a Lebanese sample.

METHODS

Methods for measuring SAO and PI on living individuals are described. The study was carried out on 200 adult individuals using CT 3D images (volume-rendering method). Reliability (intratester and intertester) was evaluated using the intraclass correlation test. A regression analysis was carried out to evaluate the association between the two measurements.

RESULTS

There were 103 females (51%) and 97 males (49%) with a mean age of 58.68 ± 19.6 years (min = 20; max = 93). The mean SAO and PI in our population were found to be 52.65° (SD = 8.16°) and 59.08° (SD = 12.53°), respectively. SAO and PI measurements were highly correlated (Pearson correlation test; r = -0.296, P < 0.0001 for our general population). PI can be predicted via SAO, i.e., SAO = (-0.193 × PI) + 64.057.

CONCLUSIONS

SAO may be an important tool, alongside PI, in defining the sagittal shape of the spine and useful for understanding its association with spinal diseases as they are not affected by postural changes.

Modern Medical Consequences of the Ancient Evolution of a Long, Flexible Lumbar Spine

Modern human bipedality is unique and requires lumbar lordosis, whereas chimpanzees, our closest relatives, have short lumbar spines rendering them incapable of lordosis. To facilitate lordosis, humans have longer lumbar spines, greater lumbosacral angle, dorsally wedged lumbar vertebral bodies, and lumbar zygapophyseal joints with both increasingly coronal orientation and further caudal interfacet distances. These features limit modern lower lumbar spine and lumbosacral joint ailments, albeit imperfectly. The more coronal zygapophyseal orientation limits spondylolisthesis, while increasing interfacet distance may limit spondylolysis. Common back pain, particularly in people who are obese or pregnant, may result from increased lumbar lordosis, causing additional mass transfer through the zygapophyseal joints rather than vertebral bodies. Reduction in lumbar lordosis, such as in flatback syndrome from decreased lumbosacral angle, can also cause back pain. Human lumbar lordosis is necessary for placing the trunk atop the pelvis and presents a balancing act not required of our closest primate relatives.

Lumbosacral Defects in a 16th-18th-Century Joseon Dynasty Skeletal Series from Korea

Paleopathological evidence for congenital and degenerative disorders of the lumbosacral vertebrae is informative about ancient individual lifeways and physical conditions. However, very few studies have focused on the paleopathology of the lumbosacral vertebrae in ancient skeletal series from East Asia. One reason for the lack of studies is that skeletal samples from East Asia are typically insufficient in size to represent populations for comparative studies within the continent. Here, we present the first comprehensive analysis of lumbosacral defects in an East Asian human skeletal sample, examining occurrences of spina bifida occulta (SBO), lumbosacral transitional vertebrae (LSTV), and spondylolysis in remains from Joseon tombs dating to the 16–18th centuries in Korea. In this study, we present an alternative methodology for understanding activities of daily life among ancient Koreans through paleopathological analysis.

Lumbar spondylolysis: A report of four cases from two generations of a family

Spondylolysis is a major cause of back pain in children and adolescents. The prevalence of spondylolysis depends on the sex, race, and congenital abnormality. These biases suggest hereditary predisposition as an etiology of spondylolysis. However, no conclusive evidence still exists regarding the inheritance for spondylolysis. Herein, we report rare cases with familial occurrence of lumbar spondylolysis. In two generations of a Japanese family, three brothers including identical twins complained of back pain related to sports activities. Clinical, radiographic, and computed tomographic examinations identified spondylolysis at L4 and L5 in all these boys. The father experienced long-term back pain and had spondylolisthesis at L4-L5 and healed spondylolysis at L5. The daughter and mother did not show any lumbar spondylolysis. The frequent development of spondylolysis at L4, a rarely affected segment, in four of six family members (66.7%) support that lumbar spondylolysis has an underlying genetic etiology, primarily autosomal dominant inheritance.

Spondylolysis in the past: A case study of hunter-gatherers from Southern Patagonia

Spondylolysis is a fracture of the pars interarticularis, the portion of the neural arch that lies between the superior articular facets and the inferior articular facets. Clinical evidence has suggested repetitive trauma to be the most probable cause, even though morphological weakness of the vertebra is probably also involved. Prevalence is between 3% and 8% in modern populations, while in archaeological samples it varies from 0% to 71.4%. Considering that very little data about this condition is available in past populations from the southern extreme of South America, the aim of this paper is to analyze the spondylolysis in a human skeletal sample from Southern Patagonia and, at the same time, to explore the prevalence of spondylolysis in archaeological contexts around the world to gain a better understanding of the results presented here. The Southern Patagonian skeletal series analyzed here showed a prevalence of 20%, with lower prevalence in the pre contact sample (11.1%) than in the contact period (23.1%). Skeletons from the Salesian Mission "Nuestra Señora de La Candelaria" showed a higher prevalence (25%) than the sample of skeletal remains recovered from outside the mission (20%), suggesting that changes in lifestyle of hunter-gatherers during contact could be implicated in the development of spondylolysis in this sample. A worldwide survey displays a wide range of prevalence figures in American and Asian samples and low diversity between African and European populations. Hunter-gatherers from Southern Patagonia showed similar values to those observed in other American samples.

Sacral fatigue fractures in children with sacral spina bifida occulta

In this report, we present two cases of 9-year-old children with spina bifida occulta (SBO) of the sacrum, who were diagnosed with sacral fatigue fractures. In both patients, MRI showed a linear signal void and high signal in sacral ala on the short tau inversion recovery sequence. Sacral SBO at the same level of the sacral fracture was observed in each patient on computed tomography images. These lesions healed with rest. This is the first literature reporting cases with sacral stress fractures who had SBO at the same level of fracture.

Increased pelvic incidence may lead to arthritis and sagittal orientation of the facet joints at the lower lumbar spine

BACKGROUND

Correct sagittal alignment with a balanced pelvis and spine is crucial in the management of spinal disorders. The pelvic incidence (PI) describes the sagittal pelvic alignment and is position-independent. It has barely been investigated on CT scans. Furthermore, no studies have focused on the association between PI and facet joint (FJ) arthritis and orientation. Therefore, our goal was to clarify the remaining issues about PI in regard to (1) physiologic values, (2) age, (3) gender, (4) lumbar lordosis (LL) and (5) FJ arthritis and orientation using CT scans.

METHODS

We retrospectively analyzed CT scans of 620 individuals, with a mean age of 43 years, who presented to our traumatology department and underwent a whole body CT scan, between 2008 and 2010. The PI was determined on sagittal CT planes of the pelvis by measuring the angle between the hip axis to an orthogonal line originating at the center of the superior end plate axis of the first sacral vertebra. We also evaluated LL, FJ arthritis and orientation of the lumbar spine.

RESULTS

596 individuals yielded results for (1) PI with a mean of 50.8°. There was no significant difference for PI and (2) age, nor (3) gender. PI was significantly and linearly correlated with (4) LL (p = < 0.0001). Interestingly, PI and (5) FJ arthritis displayed a significant and linear correlation (p = 0.0062) with a cut-off point at 50°. An increased PI was also significantly associated with more sagitally oriented FJs at L5/S1 (p = 0.01).

CONCLUSION

PI is not correlated with age nor gender. However, this is the first report showing that PI is significantly and linearly associated with LL, FJ arthritis and more sagittal FJ orientation at the lower lumbar spine. This may be caused by a higher contact force on the lower lumbar FJs by an increased PI. Once symptomatic or in the event of spinal trauma, patients with increased PI and LL could benefit from corrective surgery and spondylodesis.

Surgically treated cases of lumbar spondylolysis and isthmic spondylolisthesis: a multicenter study

STUDY DESIGN

Prospective database study.

OBJECTIVES

To grasp the characteristics of surgically treated cases with lumbar spondylolysis or isthmic spondylolisthesis.

SUMMARY OF BACKGROUND DATA

A detailed analysis of surgically treated cases with spondylolysis or isthmic spondylolisthesis has never been reported. An epidemiological study in Japan conducted on 2000 subjects found the incidence of lumbar spondylolysis in the Japanese general population (population-based study) to be 5.9% (males: 7.9%, females: 3.9%). Among 124 vertebrae with spondylolysis, there were 0.8% L2 lesions, 3.2% L3 lesions, 5.6% L4 lesions, and 90.3% L5 lesions, including 5 cases (4.3%) with multiple-level lesions.

METHODS

We have been registering surgically treated spine cases in our database since 2000. From this database, we prospectively collected cases with lumbar spondylolysis or isthmic spondylolisthesis that were treated surgically between January 2000 and December 2009. We determined the age at surgery, sex, and vertebral level of spondylolysis.

RESULTS

Of the 564 spondylolysis patients treated surgically, 66.8% were male and 33.2% were female. The mean age at surgery was 52.5 years (range, 13-84 y). There were 585 vertebrae with spondylolysis including 21 cases (3.7%) with multiple-level lesions. L5 spondylolysis affected 432 vertebrae and was the most common location (73.8%), followed by 125 L4 lesions (21.4%), 24 L3 lesions (4.1%), and 2 L2 lesions (0.7%).

CONCLUSIONS

The percentage of L4 lesions in our study was significantly higher and of L5 lesions was significantly lower than those lesions' percentages in the population-based study. L4 spondylolysis may be more unstable or cause clinical symptoms more frequently leading to more surgical intervention. The percentage of multiple-level spondylolysis was similar between the 2 studies, suggesting these patients respond relatively well to conservative treatment. The male/female ratio was 2:1 in both studies, indicating that males and females require surgery at a similar frequency.

A review of methods for evaluating the quantitative parameters of sagittal pelvic alignment

BACKGROUND CONTEXT

The sagittal alignment of the pelvis represents the basic mechanism for maintaining postural equilibrium, and a number of methods were developed to assess normal and pathologic pelvic alignments from two-dimensional sagittal radiographs in terms of positional and anatomic parameters.

PURPOSE

To provide a complete overview of the existing methods for quantitative evaluation of sagittal pelvic alignment and summarize the relevant publications.

STUDY DESIGN

Review article.

METHODS

An Internet search for terms related to sagittal pelvic alignment was performed to obtain relevant publications, which were further supplemented by selected publications found in their lists of references. By summarizing the obtained publications, the positional and anatomic parameters of sagittal pelvic alignment were described, and their values and relationships to other parameters and features were reported.

RESULTS

Positional pelvic parameters relate to the position and orientation of the observed subject and are represented by the sacral slope, pelvic tilt, pelvic overhang, sacral inclination, sacrofemoral angle, sacrofemoral distance, pelvic femoral angle, pelvic angle, and sacropelvic translation. Anatomic pelvic parameters relate to the anatomy of the observed subject and are represented by the pelvisacral angle (PSA), pelvic incidence (PI), pelvic thickness (PTH), sacropelvic angle (PRS1), pelvic radius (PR), femorosacral posterior angle (FSPA), sacral table angle (STA), and sacral anatomic orientation (SAO). The review was mainly focused on the evaluation of anatomic pelvic parameters, as they can be compared among subjects and therefore among different studies. However, ambiguous results were yielded for normal and pathologic subjects, as the reported values show a relatively high variability in terms of standard deviation for every anatomic parameter, which amounts to around 10 mm for PTH and PR; 10° for PSA, PI, and SAO; 9° for PRS1 and FSPA; and 5° for STA in the case of normal subjects and is usually even higher in the case of pathologic subjects. Among anatomic pelvic parameters, PI was the most studied and therefore represents a key parameter in the complex framework of sagittal spinal alignment and related deformities. From the reviewed studies, the regression lines for PI and the corresponding age of the subjects indicate that PI tends to increase with age for normal (PI = +0.17 × age+46.40) and scoliotic (PI = +0.20 × age+50.52) subjects and decrease with age for subjects with spondylolisis or spondylolisthesis (PI = -0.26 × age+75.69).

CONCLUSIONS

Normative values for anatomic parameters of sagittal pelvic alignment do not exist because the variability of the measured values is relatively high even for normal subjects but can be predictive for spinal alignment and specific spinopelvic pathologies.

Incidence and etiology of lumbar spondylolysis: review of the literature

BACKGROUND

Lumbar spondylolysis is a defect of the pars interarticularis known to occur as a stress fracture. Its incidence varies considerably depending on ethnicity, sex, and sports activity. However, there are few literature reviews describing its incidence in different ethnic groups or in people who engage in different sports.

METHODS

We reviewed the most relevant articles on spondylolysis published in scientific journals. First, we focused on its incidence in various ethnic groups distributed by sex, the familial occurrence, and in patients with relevant diseases. Second, we focused on the incidence of spondylolysis in relation to the sports practiced by the patients. Although placing special emphasis on the incidence of lumbar spondylolysis in the general population in Japan, we also reviewed the Japanese and English literature to investigate its incidence among those who engage in different sports.

RESULTS

The incidence of lumbar spondylolysis in the general Japanese population was 5.9%. Most studies report that the incidence in higher in male subjects than in female subjects. We found that Japanese rugby and judo players were prone to suffer lumbar spondylolysis, at an incidence of about 20%. However, the incidence for Japanese professional soccer and baseball players was much higher, at 30%, which was more than five times the incidence in the general Japanese population.

CONCLUSIONS

The incidence of lumbar spondylolysis varies depending on ethnicity, sex, family history, relevant disease, and sports activity.

Lumbar vertebral morphology and isthmic spondylolysis in a British medieval population

The British medieval population from Wharram Percy, England, has a greater prevalence of isthmic spondylolysis (11.9% of skeletons, 8.5% at the L5 level) than in modern populations (3%-6%). This may in part be due to differences in activity patterns between groups. However, Ward and Latimer (Spine 30 [2005] 1808-1814) proposed that the likelihood of developing and maintaining spondylolytic defects is also influenced by a lack of sufficient increase in mediolateral separation between articular processes in the lowest lumbar segments, given the human lumbar lordosis. Here, we demonstrate that spondylolytic individuals from Wharram Percy tend to have a less pronounced difference between mediolateral facet joint spacing of adjacent segments in the lowest lumbar region than do unaffected individuals, as seen in modern clinical and skeletal populations. These comparisons suggest that regardless of lifestyle, insufficient mediolateral increase in facet spacing predisposes people to spondylolytic defects, and so interfacet spacing patterns may have predictive utility in a clinical context. We also compare the Wharram Percy sample to a modern sample from the Hamann Todd collection with a typically modern prevalence rate. Data do not support the hypothesis that the Wharram Percy individuals had a less pronounced interfacet increase than the Hamann Todd, although they do have narrower lumbar facet spacing at the lowest three levels. Further investigation of anatomical variation underlying population-specific prevalence rates needs to be conducted.

Sacral orientation and spondylolysis

STUDY DESIGN

A descriptive study (based on skeletal material) was designed to measure sacral anatomic orientation (SAO) in individuals with and without spondylolysis.

OBJECTIVE

To test whether a relationship between SAO and spondylolysis exists.

SUMMARY OF BACKGROUND DATA

Spondylolysis is a stress fracture in the pars interarticularis (mainly of L5). The natural history of the phenomenon has been debated for years with opinions divided, i.e., is it a developmental condition or a stress fracture phenomenon. There is some evidence to suggest that sacral orientation can be a "key player" in revealing the etiology of spondylolysis.

METHODS

The pelvis was anatomically reconstructed and SAO was measured as the angle created between the intersection of a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis (PUBIS).SAO was measured in 99 adult males with spondylolysis and 125 adult males without spondylolysis. The difference between the groups was tested using an unpaired t test.

RESULTS

Spondylolysis prevalence is significantly higher in African-Americans compared to European-Americans: 5.4% versus 2.04% in males (P < 0.001) and 2.31% versus 0.4%, P < 0.001 in females. SAO was significantly lower in the spondylolytic group (44.07 degrees +/- 11.46 degrees) compared to the control group (51.07 degrees +/- 8.46 degrees, P < 0.001).

CONCLUSION

A more horizontally oriented sacrum leads to direct impingement on L5 pars interarticularis by both L4 inferior articular facet superiorly and S1 superior articular facet inferiorly. Repetitive stress due to standing (daily activities) or sitting increases the "pincer effect" on this area, and eventually may lead to incomplete synostosis of the neural arch.

Incidence of lumbar spondylolysis in the general population in Japan based on multidetector computed tomography scans from two thousand subjects

STUDY DESIGN

Epidemiological analysis using CTs.

OBJECTIVE

To investigate the true incidence of lumbar spondylolysis in the general population in Japan.

SUMMARY OF BACKGROUND DATA

Although there have been several reports on the incidence of lumbar spondylolysis, they had some weakness. One of them concerns the subjects investigated, because the incidence of lumbar spondylolysis varies considerably, and some patients are asymptomatic. In addition, most of the past studies used plain radiograph films or skeletal investigation. Therefore, the past reported incidence may not correspond to that of the general population.

METHODS

We reviewed the computed tomography (CT) scans of 2000 subjects (age: 20-92 years) who had undergone abdominal and pelvic CT on a single multidetector CT scanner for reasons unrelated to low back pain. We reviewed them for spondylolysis, spondylolytic spondylolisthesis, and spina bifida occulta (SBO) in the lumbosacral region. The grade (I-IV) of spondylolisthesis was measured using midsagittal reconstructions.

RESULTS

Lumbar spondylolysis was found in 117 subjects (5.9%). Their male-female ratio was 2:1. Multiple-level spondylolysis was found in 5 subjects (0.3%). Among these 117 subjects, there were 124 vertebrae with spondylolysis. Of them, 112 (90.3%) corresponded to L5, and 26 (21.0%) had unilateral spondylolysis.SBO was found in 154 subjects. Of them, 25 had spondylolysis (16.2%), whereas, in 1846 subjects without SBO, 92 had spondylolysis (5.0%). The incidence of spondylolysis among the patients with SBO was significantly higher than that in subjects without SBO (Odd ratio was 3.7-fold).Of 124 vertebrae with spondylolysis, 75 (60.5%) showed low-grade (Meyerding grade I or II) spondylolisthesis, and no subject presented high-grade spondylolisthesis. Spondylolisthesis was found in 74.5% of the subjects with bilateral spondylolysis, and in 7.7% of those with unilateral spondylolysis.

CONCLUSION

The incidence of lumbar spondylolysis in the Japanese general population was 5.9% (males: 7.9%, females: 3.9%).

Biomechanical implications of degenerative joint disease in the apophyseal joints of human thoracic and lumbar vertebrae

An experimental technique for quantifying load-sharing in cadaveric spines is used to test the hypothesis that degenerative changes in human apophyseal joints are directly related to high levels of compressive load-bearing by these joints. About 36 cadaveric thoraco-lumbar motion segments aged 64-92 years were subjected to a compressive load of 1.5 kN. The distribution of compressive stress was measured in the intervertebral discs using a miniature pressure transducer, and stress measurements were summed over area to give the compressive force resisted by the disc. This was subtracted from the applied 1.5 kN to indicate compressive load-bearing by the apophyseal joints. The cartilage of each apophyseal joint surface was then graded for degree of degeneration. After maceration, each joint surface was scored for degenerative joint disease (DJD) affecting the bone. Results demonstrated that the apophyseal joints resisted 5-96% (mean 45%) of the applied compressive force. A significant positive correlation was demonstrated between age and cartilage degeneration, age and DJD bone score, apophyseal joint load-bearing and bone score, and cartilage score and load-bearing. The latter correlation was strongest for load-bearing above 50%. Ordinal regression showed that the variables describing bone DJD (marginal osteophytes, pitting, bony contour change, and eburnation) were significantly correlated with degree of cartilage degeneration. It is concluded that in elderly individuals apophyseal joint load-bearing above a threshold of 50% is associated with severe degenerative changes in cartilage and bone, and that markers of DJD observed palaeopathologically may be used as predictors of such loadingin life.

Sacral orientation revisited

STUDY DESIGN

A descriptive study of the sacral anatomic orientation (SAO) and its association with pelvic incidence (PI).

OBJECTIVE

To introduce the concept of SAO, establish a method for measuring it, and evaluate its association with pelvic orientation.

SUMMARY OF BACKGROUND DATA

Pelvic orientation (PO) is considered a key factor in spinal shape and balance. Sacral slope (SS), PI, and pelvic tilt (PT) are the most frequently used parameters for evaluating PO. Nevertheless, the association between the anatomic orientation of the sacrum and these parameters has never been established. The aim of the present study is to define the anatomic orientation of the sacrum, to establish a reliable method for measuring it, and to examine its association with PI.

METHODS

SAO was defined as the angle created between the intersection of a line running parallel to the superior endplate surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis. Methods for measuring SAO and PI on both skeletal populations and living individuals are described. The study was carried out on 424 skeletons (articulated pelves) using a three-dimensional digitizer and on 20 adult individuals using CT three-dimensional images (volume-rendering method). Reliability (intratester and intertester) was assessed using intraclass correlation test. A regression analysis was carried out to evaluate the association between the two measurements.

RESULTS

The mean SAO and PI in the human skeletal population were found to be 48.46 degrees +/- 10.17 degrees and 54.08 degrees +/- 12.64 degrees , respectively and of the living individuals (CT) 52.76 degrees +/- 10.31 degrees and 57.14 degrees +/- 13.08 degrees , respectively. SAO and PI measurements were highly correlated (r = -0.824, and r = -0.828, P < 0.001 for skeletal material and living individuals, respectively). PI can be predicted via SAO, i.e., PI = [-0.971 x SAO] + 101.16 degrees .

CONCLUSIONS

The newly suggested parameter (SAO) may be an important tool in defining the sagittal shape of the spine and understanding its association with spinal diseases.

Orientation of the human sacrum: Anthropological perspectives and methodological approaches

Discovering the nature of sacral orientation is of considerable anthropological importance. Therefore, this study aims at presenting a new anthropologically based definition for sacral anatomical orientation (SAO) angle, establishing standards of SAO for human population; examining the relationship between pelvic incidence (PI) and SAO; and associating SAO with demographic parameters. The study population consisted of 424 adult and 14 sub-adult (13-18 years, for SAO only) pelvises. Sacral orientation was measured using two different definitions: a) SAO is the angle created between the intersection of a line running parallel to the superior surface of the sacrum and a line running between the anterior superior iliac spine (ASIS) and the anterior-superior edge of the symphysis pubis; b) PI is the angle created between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the middle of the axis of the acetabulum. SAO was measured using a specially designed mechanical measurement tool and a 3D digitizer. PI was measured via the 3D digitizer. The methods developed by us for measuring SAO and PI in skeletal material are valid and reliable. SAO and PI measures were highly correlated (r = -0.824, P < 0.001). The average SAO was 49.01 degrees (SD = 10.16), and the average PI 54.08 degrees (SD = 12.64). SAO was independent of ethnicity and sex, yet age dependent. This study establishes a methodology for estimating SAO and PI in skeletal material and furnishes the anthropological milieu with base line data regarding these parameters. Future studies in human evolution can greatly benefit from this study.