Increased pelvic incidence may lead to arthritis and sagittal orientation of the facet joints at the lower lumbar spine
© Jentzsch et al.; licensee BioMed Central Ltd. 2013
Received: 28 May 2013
Accepted: 1 November 2013
Published: 5 November 2013
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.
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.
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).
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.
KeywordsPelvic incidence Age Gender Lumbar Lordosis Facet joint arthritis Orientation
Pelvic rotation has emerged from the genesis of an erect position of the human spine . Nowadays, a proper sagittally oriented pelvis, which acts as a basis for the building block of the entire spine, and an ideal lordotic curvature of the spine equilibrate each other in regard to overall spinal balance [2, 3]. Nevertheless, aging and spinal deformities, such as spondylolisthesis may change spinal balance . Thus, the establishment of a neutral upright sagittal alignment with the pelvis and spine in sync is essential in the management of spinal disorders [5, 6].
Yet, there are a handful of remaining issues about the PI. (1) It has been studied extensively on X-rays [17, 18]. But overlap or magnification of structures my falsify the measured angle [7, 17]. Furthermore, very few studies [4, 12, 13] in the English literature have investigated the PI on CT scans, which are more more precise and more commonly used nowadays. (2) PI has been reported to increase until the age of ten and than stabilize [19–21], but other reports [22–26] have shown an increase later on during life, especially with spinal deformities, such as spondylolisthesis, or sacral fractures. (3) Even though most studies [14, 27–29] have not found a gender difference, another study  has documented significant higher values for females. (4) Interestingly, PI may increase in order to compensate for a decrease in lumbar lordosis (LL) [24, 25]. A simple predictive equation has been proposed recently : LL = PI +9° (+/− 9°). (5) Facet joint (FJ) arthritis may arise from several misbalanced forces, such as increased LL, which leads to higher contact forces on the FJs, compression, rotation, and shear as well as more sagittal orientation of the lower lumbar spine, which may lead to spondylolysis and spondylolisthesis [31–36]. However, this may be prevented by compensatory mechanisms of the pelvis and a previous osteologic study  has linked increased pelvic lordosis to FJ arthritis at L5/S1. Other previous studies [38, 39] have also found an association between the pelvic geometry and lumbar degenerative processes. However, none have focused on the association between PI and FJ arthritis, let alone PI and FJ orientation. Therefore, we hypothesized that increased PI is associated with FJ arthritis and changes in FJ orientation.
Therefore, our goal was to clarify the remaining issues about PI in regard to (1) physiologic values, (2) age, (3) gender, (4) LL and, according to our main hypothesis (5) FJ arthritis and orientation using CT scans.
The study has been approved by the local research ethics review committee (Kantonale Ethikkommission Zürich (KEK-ZH)-Nr.2011-0507). We included and retrospectively analyzed CT scans of 620 individuals (2480 functional units consisting of two FJs and one intervertebral disc on each level between L2 and S1) , with a median age of 39 (IQR 27–54), who presented to our traumatology department and underwent a whole body CT scan, including the pelvis and lumbar spine, between 2008 and 2010. Exclusion criteria involved fractures of the lumbar spine and pelvis that may have changed the spino-pelvic alignment and CT studies that did not include sagittally reconstructed pelvic cross-sections. A dual-source computed tomography scanner (Somatom Definition, Siemens Healthcare, Forchheim, Germany) was used . Our study utilized CT scans instead of plain radiographs, because there is a paucity on studies about the PI and FJs are more accurately displayed [12, 13, 42].
All statistical analysis was performed by the Institute for Social and Preventive Medicine, Division of Biostatistics at the University of Zuerich, using the R program . In a first step of the analysis, we expressed distribution of variables using means and standard deviation (SD) for normally distributed data, and medians and interquartile ranges for non-normally distributed data. We tested data for normality with the Kolmogorow-Smirnow test and performed quantile-quantile plots of dependent variables. Several different statistical approaches were applied to test the remaining issues mentioned above and our main hypothesis , which assumed an association between an increased PI and FJ arthritis as well as changes in FJ orientation. (1) PI is a numerical measure without normal distribution, therefore simple linear regression models were applied. Therefore, PI was log transformed. An F-Test was used for nominal explanatory variables, such as (2) age, (3) gender and (5) FJ orientation. To compare PI with the numerical measure (4) LL, a linear regression was used. (5) FJ arthritis is an ordinal measure and in order to compare it to PI, which was not log transformed, FJ arthritis was used as an outcome and a proportional odds model was performed. This study is an observational study, which means that analysis follows a descriptive and exploratory form and p-values are interpreted as a quantitative measure of the evidence against the null hypothesis. Significant difference was assumed if p < 0.05.
PI and Age
PI and Gender
There was no significant difference for PI and age (p = 0.07)
≤ 40 years
> 40 years
≤ 30 years
≥ 71 years
PI and LL
We did not find a significant difference for PI and gender (p = 0.28)
PI and FJ Arthritis and Orientation
Our study investigated the largest sample of CT scans from different individuals in the literature in regard to PI and (1) its physiologic values, (2) age, (3) gender, (4) LL and marks the first study to investigate its relationship with (5) FJ arthritis and orientation. We were able to show that the (1) mean value for PI on CT scans ranges around 50.8°. PI was not significantly correlated with (2) age, nor (3) gender. However, we found a significant linear relationship between PI and (4) LL, (5) FJ arthritis and sagittal FJ orientation at the lower lumbar spine, namely L5/S1. PI and FJ orientation at the upper lumbar spine were not significantly correlated.
PI and Age
PI and Gender
PI and LL
Main hypothesis: PI and FJ Arthritis and Orientation
Our study marks the first study to investigate the association of PI with FJ arthritis and orientation. According to our hypothesis and as a novel finding, PI was significantly and linearly associated with FJ arthritis and sagittally oriented FJs at the lower lumbar spine, namely L5/S1 (Figures 7, 8 and 9). However, comparison of PI with FJ orientation at the upper lumbar spine did not reveal any significant differences. This is similar to a recent study by Toy et al. , who investigated 120 cadaver specimen and concluded that the highest quarter of pelvic lordosis is associated with FJ arthritis at L5/S1. According to Toy et al. , pelvic lordosis describes the angle between the pelvic radius line and a line tangent to the upper S1 endplate that intersected at the posterior superior corner of S1. However, they did not mention an association between PI and FJ arthritis. They also used a goniometer on the osteologic specimen, which may lead to more imprecise values. This is also in line with a study by Labelle et al. , who found a linear association between PI and spondylolisthesis. Our results support their hypothesis that an increased PI may lead to a higher mechanical stress on the FJs. An association of FJ arthritis with sagittal FJ orientation of the lower lumbar spine has been reported in a study of CT scans with 188 individuals by Kalichman et al.  and a similar study by Liu et al.  as well as a MRI study if 111 individuals by Fujiwara et al. . Considering that the lowest three lumbar FJs carry the highest loads and LL leads to higher contact force on the FJs , it may be postulated that increased PI may also lead to higher contact force on the lower FJs and cause FJ arthritis along with more sagittal FJ orientation. Individuals with increased PI may therefore be at high risk for FJ arthritis at the lower lumbar spine. While FJ arthritis may be considered a degenerative disease, more sagittal FJ orientation of the lower lumbar spine may be a balancing mechanism.
The establishment of a neutral upright sagittal alignment with the pelvis and spine in sync is essential in the management of spinal disorders [5, 6]. Our study aids in the ongoing process  of defining the optimal spinal balance. It validates that PI remains a key parameter in sagittal balance and provides another mean value in a large patient population. We also present an easy method for quick and accurate evaluation of PI on sagittal slices of CT scans that does not require complicated reconstruction of 3D images. Patients with increased PI are more likely to present with FJ arthritis and possibly from associated back pain. Once these patients with increased PI (and LL) become symptomatic, orthopaedic (trauma) surgeons may consider FJ infiltration and/or establishing less lordosis with percutaneous instrumentation, where available, in order to restorce spino-pelvic balance and prevent FJ arthritis if they feel that this may cause problems for the patient. In these trauma patients with increased PI (and LL), a fracture at the lumbar spine in need of spinal surgery, spondylodesis may be preferred over percutaneous instrumentation because these patients are more likely to suffer from FJ arthritis and its related pain.
In conclusion, our study showed that the mean value for PI on CT scans ranges around 50.8°. PI is neither significantly correlated with age nor gender. However, this is the first report showing that PI is significantly and linearly associated with LL, FJ arthritis and sagittal FJ orientation at the lower lumbar spine. Increased PI may lead to higher contact force on the lower lumbar FJs and cause FJ arthritis along with more sagittal FJ orientation. Individuals with increased PI and (and increased LL) may therefore be at high risk for FJ arthritis at the lower lumbar spine. Patients with increased PI (and increased LL) could benefit from corrective surgery and spondylodesis, once symptomatic or in the event of trauma.
We would like to thank Ms. Carol De-Simio-Hilton for her help with the preparation of the figures and Ms. Sina Rueeger from the Institute for Social and Preventive Medicine, Division of Biostatistics at the University of Zurich for her help with statistical analysis.
- Le Huec JC, Roussouly P: Sagittal spino-pelvic balance is a crucial analysis for normal and degenerative spine. Eur Spine J. 2011, 20 (Suppl 5): 556-557.View ArticlePubMedPubMed CentralGoogle Scholar
- Legaye J, Duval-Beaupère G, Hecquet J, Marty C: Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves. Eur Spine J. 1998, 7 (2): 99-103. 10.1007/s005860050038.View ArticlePubMedPubMed CentralGoogle Scholar
- Roussouly P, Gollogly S, Berthonnaud E, Dimnet J: Classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis in the standing position. Spine. 2005, 30 (3): 346-353. 10.1097/01.brs.0000152379.54463.65.View ArticlePubMedGoogle Scholar
- Vrtovec T, Janssen MM, Pernuš F, Castelein RM, Viergever MA: Analysis of pelvic incidence from 3-dimensional images of a normal population. Spine (Phila Pa 1976). 2012, 37 (8): 479-485. 10.1097/BRS.0b013e31823770af.View ArticleGoogle Scholar
- Kuntz C, Levin LS, Ondra SL, Shaffrey CI, Morgan CJ: Neutral upright sagittal spinal alignment from the occiput to the pelvis in asymptomatic adults: a review and resynthesis of the literature. J Neurosurg Spine. 2007, 6 (2): 104-112. 10.3171/spi.2007.6.2.104.View ArticlePubMedGoogle Scholar
- Schwab F, Patel A, Ungar B, Farcy JP, Lafage V: Adult spinal deformity-postoperative standing imbalance: how much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery. Spine (Phila Pa 1976). 2010, 35 (25): 2224-2231. 10.1097/BRS.0b013e3181ee6bd4.View ArticleGoogle Scholar
- Vrtovec T, Janssen MM, Likar B, Castelein RM, Viergever MA, Pernuš F: A review of methods for evaluating the quantitative parameters of sagittal pelvic alignment. Spine J. 2012, 12 (5): 433-446. 10.1016/j.spinee.2012.02.013.View ArticlePubMedGoogle Scholar
- Duval-Beaupère G, Schmidt C, Cosson P: A Barycentremetric study of the sagittal shape of spine and pelvis: the conditions required for an economic standing position. Ann Biomed Eng. 1992, 20 (4): 451-462. 10.1007/BF02368136.View ArticlePubMedGoogle Scholar
- Philippot R, Wegrzyn J, Farizon F, Fessy MH: Pelvic balance in sagittal and Lewinnek reference planes in the standing, supine and sitting positions. Orthop Traumatol Surg Res. 2009, 95 (1): 70-76. 10.1016/j.otsr.2008.01.001.View ArticlePubMedGoogle Scholar
- Sturesson B, Uden A, Vleeming A: A radiostereometric analysis of movements of the sacroiliac joints during the standing hip flexion test. Spine (Phila Pa 1976). 2000, 25 (3): 364-368. 10.1097/00007632-200002010-00018.View ArticleGoogle Scholar
- Jackson RP, Peterson MD, McManus AC, Hales C: Compensatory spinopelvic balance over the hip axis and better reliability in measuring lordosis to the pelvic radius on standing lateral radiographs of adult volunteers and patients. Spine (Phila Pa 1976). 1998, 23 (16): 1750-1767. 10.1097/00007632-199808150-00008.View ArticleGoogle Scholar
- Peleg S, Dar G, Medlej B, Steinberg N, Masharawi Y, Latimer B, et al: Orientation of the human sacrum: anthropological perspectives and methodological approaches. Am J Phys Anthropol. 2007, 133 (3): 967-977. 10.1002/ajpa.20599.View ArticlePubMedGoogle Scholar
- Peleg S, Dar G, Steinberg N, Peled N, Hershkovitz I, Masharawi Y: Sacral orientation revisited. Spine (Phila Pa 1976). 2007, 32 (15): 397-404. 10.1097/BRS.0b013e318074d676.View ArticleGoogle Scholar
- Mac-Thiong JM, Roussouly P, Berthonnaud E, Guigui P: Sagittal parameters of global spinal balance: normative values from a prospective cohort of seven hundred nine Caucasian asymptomatic adults. Spine (Phila Pa 1976). 2010, 35 (22): 1193-1198. 10.1097/BRS.0b013e3181e50808.View ArticleGoogle Scholar
- Lazennec JY, Ramaré S, Arafati N, Laudet CG, Gorin M, Roger B, et al: Sagittal alignment in lumbosacral fusion: relations between radiological parameters and pain. Eur Spine J. 2000, 9 (1): 47-55. 10.1007/s005860050008.View ArticlePubMedPubMed CentralGoogle Scholar
- Lafage V, Schwab F, Skalli W, Hawkinson N, Gagey PM, Ondra S, et al: Standing balance and sagittal plane spinal deformity: analysis of spinopelvic and gravity line parameters. Spine (Phila Pa 1976). 2008, 33 (14): 1572-1578. 10.1097/BRS.0b013e31817886a2.View ArticleGoogle Scholar
- Vaz G, Roussouly P, Berthonnaud E, Dimnet J: Sagittal morphology and equilibrium of pelvis and spine. Eur Spine J. 2002, 11 (1): 80-87. 10.1007/s005860000224.View ArticlePubMedGoogle Scholar
- Vialle R, Levassor N, Rillardon L, Templier A, Skalli W, Guigui P: Radiographic analysis of the sagittal alignment and balance of the spine in asymptomatic subjects. J Bone Joint Surg Am. 2005, 87 (2): 260-267. 10.2106/JBJS.D.02043.View ArticlePubMedGoogle Scholar
- Mac-Thiong JM, Berthonnaud E, Dimar JR, Betz RR, Labelle H: Sagittal alignment of the spine and pelvis during growth. Spine (Phila Pa 1976). 2004, 29 (15): 1642-1647. 10.1097/01.BRS.0000132312.78469.7B.View ArticleGoogle Scholar
- Mangione P, Gomez D, Senegas J: Study of the course of the incidence angle during growth. Eur Spine J. 1997, 6 (3): 163-167. 10.1007/BF01301430.View ArticlePubMedPubMed CentralGoogle Scholar
- Marty C, Boisaubert B, Descamps H, Montigny JP, Hecquet J, Legaye J, et al: The sagittal anatomy of the sacrum among young adults, infants, and spondylolisthesis patients. Eur Spine J. 2002, 11 (2): 119-125. 10.1007/s00586-001-0349-7.View ArticlePubMedPubMed CentralGoogle Scholar
- Schwab F, Lafage V, Boyce R, Skalli W, Farcy JP: Gravity line analysis in adult volunteers: age-related correlation with spinal parameters, pelvic parameters, and foot position. Spine (Phila Pa 1976). 2006, 31 (25): 959-967. 10.1097/01.brs.0000248126.96737.0f.View ArticleGoogle Scholar
- Labelle H, Roussouly P, Berthonnaud E, Transfeldt E, O'Brien M, Chopin D, et al: Spondylolisthesis, pelvic incidence, and spinopelvic balance: a correlation study. Spine (Phila Pa 1976). 2004, 29 (18): 2049-2054. 10.1097/01.brs.0000138279.53439.cc.View ArticleGoogle Scholar
- Hanson DS, Bridwell KH, Rhee JM, Lenke LG: Correlation of pelvic incidence with low- and high-grade isthmic spondylolisthesis. Spine (Phila Pa 1976). 2002, 27 (18): 2026-2029. 10.1097/00007632-200209150-00011.View ArticleGoogle Scholar
- Mendoza-Lattes S, Ries Z, Gao Y, Weinstein SL: Natural history of spinopelvic alignment differs from symptomatic deformity of the spine. Spine (Phila Pa 1976). 2010, 35 (16): 792-798. 10.1097/BRS.0b013e3181d35ca9.View ArticleGoogle Scholar
- Hart RA, Badra MI, Madala A, Yoo JU: Use of pelvic incidence as a guide to reduction of H-type spino-pelvic dissociation injuries. J Orthop Trauma. 2007, 21 (6): 369-374. 10.1097/BOT.0b013e31806dd959.View ArticlePubMedGoogle Scholar
- Janssen MM, Drevelle X, Humbert L, Skalli W, Castelein RM: Differences in male and female spino-pelvic alignment in asymptomatic young adults: a three-dimensional analysis using upright low-dose digital biplanar X-rays. Spine. 2009, 34 (23): E826-E832. 10.1097/BRS.0b013e3181a9fd85.View ArticlePubMedGoogle Scholar
- Boulay C, Tardieu C, Hecquet J, Benaim C, Mouilleseaux B, Marty C, et al: Sagittal alignment of spine and pelvis regulated by pelvic incidence: standard values and prediction of lordosis. Eur Spine J. 2006, 15 (4): 415-422. 10.1007/s00586-005-0984-5.View ArticlePubMedGoogle Scholar
- Mac-Thiong JM, Labelle H, Berthonnaud E, Betz RR, Roussouly P: Sagittal spinopelvic balance in normal children and adolescents. Eur Spine J. 2007, 16 (2): 227-234. 10.1007/s00586-005-0013-8.View ArticlePubMedGoogle Scholar
- Schwab F, Lafage V, Patel A, Farcy JP: Sagittal plane considerations and the pelvis in the adult patient. Spine (Phila Pa 1976). 2009, 34 (17): 1828-1833. 10.1097/BRS.0b013e3181a13c08.View ArticleGoogle Scholar
- Kirkaldy-Willis WH, Paine KW, Cauchoix J, McIvor G: Lumbar spinal stenosis. Clin Orthop Relat Res. 1974, 99: 30-50.View ArticlePubMedGoogle Scholar
- Adams MA, Hutton WC: The effect of posture on the role of the apophysial joints in resisting intervertebral compressive forces. J Bone Joint Surg Br. 1980, 62 (3): 358-362.PubMedGoogle Scholar
- Konz RJ, Goel VK, Grobler LJ, Grosland NM, Spratt KF, Scifert JL, et al: The pathomechanism of spondylolytic spondylolisthesis in immature primate lumbar spines in vitro and finite element assessments. Spine (Phila Pa 1976). 2001, 26 (4): 38-49. 10.1097/00007632-200102150-00003.View ArticleGoogle Scholar
- Kalichman L, Suri P, Guermazi A, Li L, Hunter DJ: Facet orientation and tropism: associations with facet joint osteoarthritis and degeneratives. Spine (Phila Pa 1976). 2009, 34 (16): 579-585. 10.1097/BRS.0b013e3181aa2acb.View ArticleGoogle Scholar
- Liu HX, Shen Y, Shang P, Ma YX, Cheng XJ, Xu HZ: Asymmetric Facet Joint Osteoarthritis and its Relationships to Facet Orientation, Facet Tropism and Ligamentum Flavum Thickening. J Spinal Disord Tech. 2012, Epub ahead of printGoogle Scholar
- Fujiwara A, Tamai K, An HS, Lim TH, Yoshida H, Kurihashi A, et al: Orientation and osteoarthritis of the lumbar facet joint. Clin Orthop Relat Res. 2001, 385: 88-94.View ArticlePubMedGoogle Scholar
- Toy JO, Tinley JC, Eubanks JD, Qureshi SA, Ahn NU: Correlation of sacropelvic geometry with disc degeneration in spondylolytic cadaver specimens. Spine (Phila Pa 1976). 2012, 37 (1): 10-15. 10.1097/BRS.0b013e31823b0440.View ArticleGoogle Scholar
- Peleg S, Dar G, Steinberg N, Masharawi Y, Been E, Abbas J, et al: Sacral orientation and spondylolysis. Spine (Phila Pa 1976). 2009, 34 (25): 906-910. 10.1097/BRS.0b013e3181b34b75.View ArticleGoogle Scholar
- Curylo LJ, Edwards C, DeWald RW: Radiographic markers in spondyloptosis: implications for spondylolisthesis progression. Spine (Phila Pa 1976). 2002, 27 (18): 2021-2025. 10.1097/00007632-200209150-00010.View ArticleGoogle Scholar
- Fujiwara A, Tamai K, Yamato M, An HS, Yoshida H, Saotome K, et al: The relationship between facet joint osteoarthritis and disc degeneration of the lumbar spine: an MRI study. Eur Spine J. 1999, 8 (5): 396-401. 10.1007/s005860050193.View ArticlePubMedPubMed CentralGoogle Scholar
- Karlo C, Gnannt R, Frauenfelder T, Leschka S, Bruesch M, Wanner GA, et al: Whole-body CT in polytrauma patients: effect of arm positioning on thoracic and abdominal image quality. Emerg Radiol. 2011, 18 (4): 285-93. 10.1007/s10140-011-0948-5. doi: 10.1007/s10140-011-0948-5. Epub 2011 Apr 7.View ArticlePubMedGoogle Scholar
- Carrera GF, Haughton VM, Syvertsen A, Williams AL: Computed tomography of the lumbar facet joints. Radiology. 1980, 134 (1): 145-148.View ArticlePubMedGoogle Scholar
- Kalichman L, Li L, Kim DH, Guermazi A, Berkin V, O'Donnell CJ, et al: Facet joint osteoarthritis and low back pain in the community-based population. Spine (Phila Pa 1976). 2008, 33 (23): 2560–-2565.View ArticleGoogle Scholar
- Stokes IA: Three-dimensional terminology of spinal deformity. A report presented to the scoliosis research society by the scoliosis research society working group on 3-D terminology of spinal deformity. Spine. 1994, 19 (2): 236-248.View ArticlePubMedGoogle Scholar
- Holdsworth F: Fractures, dislocations, and fracture-dislocations of the spine. J Bone Joint Surg Am. 1970, 52 (8): 1534-1551.PubMedGoogle Scholar
- Pathria M, Sartoris DJ, Resnick D: Osteoarthritis of the facet joints: accuracy of oblique radiographic assessment. Radiology. 1987, 164 (1): 227-230.View ArticlePubMedGoogle Scholar
- Suri P, Miyakoshi A, Hunter DJ, Jarvik JG, Rainville J, Guermazi A, et al: Does lumbar spinal degeneration begin with the anterior structures? a study of the observed epidemiology in a community-based population. BMC Musculoskelet Disord. 2011, 12: 202-10.1186/1471-2474-12-202.View ArticlePubMedPubMed CentralGoogle Scholar
- Masharawi YM, Alperovitch-Najenson D, Steinberg N, Dar G, Peleg S, Rothschild B, et al: Lumbar facet orientation in spondylolysis: a skeletal study. Spine (Phila Pa 1976). 2007, 32 (6): 176-180. 10.1097/01.brs.0000257565.41856.0f.View ArticleGoogle Scholar
- Schuller S, Charles YP, Steib JP: Sagittal spinopelvic alignment and body mass index in patients with degenerative spondylolisthesis. Eur Spine J. 2011, 20 (5): 713-719. 10.1007/s00586-010-1640-2.View ArticlePubMedGoogle Scholar
- Mahato NK: Facet dimensions, orientation, and symmetry at L5-S1 junction in lumbosacral transitional States. Spine (Phila Pa 1976). 2011, 36 (9): 569-573. 10.1097/BRS.0b013e3181f6ecb2.View ArticleGoogle Scholar
- Hasegawa K, Shimoda H, Kitahara K, Sasaki K, Homma T: What are the reliable radiological indicators of lumbar segmental instability?. J Bone Joint Surg Br. 2011, 93 (5): 650-657.View ArticlePubMedGoogle Scholar
- Team RDC: A Language and Environment for Statistical Computing. 2009, Vienna, Austria: A Language and Environment for Statistical Computing, ISBN 3-900051-07-0 edGoogle Scholar
- Kirkwood BR, Sterne JAC: Essential Medical Statistics. 2003, Oxford: Blackwell Scientific Publications, 2Google Scholar
- Boden SD, Riew KD, Yamaguchi K, Branch TP, Schellinger D, Wiesel SW: Orientation of the lumbar facet joints: association with degenerative disc disease. J Bone Joint Surg Am. 1996, 78 (3): 403-411.PubMedGoogle Scholar
- Swanepoel MW, Adams LM, Smeathers JE: Human lumbar apophyseal joint damage and intervertebral disc degeneration. Ann Rheum Dis. 1995, 54 (3): 182-188. 10.1136/ard.54.3.182.View ArticlePubMedPubMed CentralGoogle Scholar
- Kirkaldy-Willis WH, Farfan HF: Instability of the lumbar spine. Clin Orthop Relat Res. 1982, 165: 110-123.PubMedGoogle Scholar
- Kim JS, Kroin JS, Buvanendran A, Li X, van Wijnen AJ, Tuman KJ, et al: Characterization of a new animal model for evaluation and treatment of back pain due to lumbar facet joint osteoarthritis. Arthritis Rheum. 2011, 63 (10): 2966-2973. 10.1002/art.30487.View ArticlePubMedPubMed CentralGoogle Scholar
- Maus T: Imaging the back pain patient. Phys Med Rehabil Clin N Am. 2010, 21 (4): 725-766. 10.1016/j.pmr.2010.07.004.View ArticlePubMedGoogle Scholar
- Eubanks JD, Lee MJ, Cassinelli E, Ahn NU: Prevalence of lumbar facet arthrosis and its relationship to age, sex, and race: an anatomic study of cadaveric specimens. Spine (Phila Pa 1976). 2007, 32 (19): 2058-2062. 10.1097/BRS.0b013e318145a3a9.View ArticleGoogle Scholar
- American College of Surgeons CoT: National Trauma Data Bank Annual Report. 23-http://www.facs.org/trauma/ntdb/pdf/ntdbannualreport2010.pdf, accessed on November 4th 2013
- Mays S: Spondylolysis, spondylolisthesis, and lumbo-sacral morphology in a medieval English skeletal population. Am J Phys Anthropol. 2006, 131 (3): 352-362. 10.1002/ajpa.20447.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2342/13/34/prepub
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