Sacropelvic Parameters Research Articles

Quantifying the Spinal Lordosis Ratio Unique to the Type of Spinal Sagittal Alignment in a Normal Population.

Data collection of radiological parameters in non-pathological adult spines. Establishing a baseline database for measurements of the spinal lordosis ratio between upper and lower arcs of the lumbar spine unique to each type of spine described by Roussouly's classification. Illustrating the importance of correct rationing of the upper and lower arcs. Standardised standing true lateral plain radiographs of the spine (including base of skull and proximal femurs) from 373 adult volunteers were obtained. Exclusion criteria : any history of disease involving the spine, pelvis, hips or lower limbs. Incidental detection of any spinal deformity on radiography also excluded further participation in this study. Sacro-pelvic parameters data collected : Pelvic Incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS), location of Inflection Point, number of vertebras in the spinal lordosis and type of Roussouly's spine. Values of upper arc, lower arc and spinal lordosis ratio (SLR) was determined. Bivariate analysis revealed statistically significant (P < .0001) correlation between the types of sagittal spinal alignments based on Roussouly's classification and the SLR. Type 1: SLR .76 ± .17, Type 2: SLR .60 ± .18, Type 3 with anteverted pelvis: SLR .53 ± .11, Type 3: SLR .49 ± .12, Type4: SLR .41 ± .11. With this data we are able to quantify the ratio of lumbar lordosis unique to each type of Roussouly's spine. It functions as a guide when planning lumbar spine surgeries in order to restore the SLR correctly and thus prevent post-op complications such as proximal junction kyphosis.

Assessment of the acetabular version in relation to sagittal sacropelvic parameters.

The relationship between acetabular orientation and the sacropelvic parameters is of interest to both hip and spine surgeons as it is increasingly clear disease in one area can affect the other, including the outcome of surgical procedures. The aim of this study was to further clarify the relationship between measures of acetabular orientation and sacropelvic parameters. This study utilized a trauma CT database. A total of 100 scans on adult patients without overt hip or spinal disease were included. Measures of acetabular orientation included the acetabular sagittal angle (ASA) which uses the anterior pelvic plane as a reference and sacroacetabular angle which uses the sacral endplate as a reference (SA); spinopelvic parameters include the pelvic incidence (PI), sacral anatomic orientation (SAO) and pelvic thickness (PTH). Mean age 48.2years (SD 18.0), 62% male. Mean values were: PI 50.5, SAO 50.7, PTH 106.4 mm, ASA-right 62.1, ASA-left 64.0, SA-right 67.2, and SA-left 65.4. There was substantial correlation between PI and SA (r=0.628-0.630) and also between SAO and SA (-0.657 to -0.692). Liner regression determined SA was best predicted by the model: SA=81×SAO+0.36×PI. When using the anterior pelvic plane as a reference to define acetabular orientation, there does not appear to be any significant relationship between the sagittal orientation of the acetabulum and sacropelvic parameters. Using the sacrum as a common point of reference allows some further understanding of the interplay between pelvic parameters and the orientation of the acetabulum.

Лечение костно-болевого синдрома у пациентов с компрессионными, неосложненными переломами поясничных позвонков на II-III этапах восстановительного лечения

The aim of this prospective study is to improve the results of treating type A1 and A2 uncomplicated vertebral compression fractures using intratissual electric stimulation (ITES) during II and III stages of rehabilitation treatment. Materials and Methods. The study analyses the use of intratissual electric stimulation (ITES) for treating bone pain syndrome of the patients with type A1 and A2 mono and bisegmental spinal fractures (according to Magerl classification) in a distant period. The whole population is 86 patients, aged from 45 to 65. In-patients were treated using vertebral column extension, some physical therapy and medication. The observation period lasted 12-36 months. It is the stage of control observation. The patients who complained of constant and reemerging pain syndrome were treated using intratissual electric stimulation (ITES). Immediate, short- and long-term outcome analysis was carried out. It is the final stage of the treatment. Clinical, neurotic and rehabilitation status of the patients is analized taking into account Sagittal balance parameters, the spinal canal condition and rehabilitation vectors with numerical ratings. The objective pain assessment was performed by measuring skin surface electric potential according to Gerasimov (1991). The quality of life was assessed using Oswestry Disability Index (ODI). Results. The analysis of morphometric characteristics pointed out changes in sacro-pelvic correlation (LSB), flattening of lumbar lordosis, stenosis of the spinal canal, post-traumatic changes and involution in lumbar and thoracic vertebrae. The control stage of the research revealed significant improvement of patients’ sacro-pelvic balance parameters, pain syndrome elimination and the improvement of the quality life. Conclusion. The pathogenetically substantiated method of treating adult or elderly patients with spinal traumas, the use of intratissual electric stimulation at the outpatient rehabilitation stage prove to be effective.

Sacropelvic Parameters and L5 Spondylolysis: Computed Tomography Analysis.

Study DesignRetrospective analysis of computed tomography scans.PurposeThis study aims to determine the association of sagittal sacropelvic parameters with L5 spondylolysis.Overview of LiteratureThe association of increased pelvic incidence (PI) and decreased sacral table angle (STA) with spondylolysis has been reported, but no study has simultaneously analyzed multiple sacropelvic variables to compare their association.MethodsIn this study, computed tomography scans obtained to assess major trauma in patients aged >16 years were analyzed. Scans meeting one of the following criteria were excluded: abnormal anatomy, previous spine or hip/pelvis surgery, or spinal pathology, including deformity, infection, tumor, or trauma. sacral anatomic orientation (SAO), PI, pelvic thickness (PTH), femoro-sacral posterior angle (FSPA), STA, and sacral kyphosis (SK) were measured.ResultsOverall, 202 scans were analyzed: 25 with L5 spondylolysis and 177 normal. Among the groups, a significant difference was observed in SAO (43.3° vs. 51.6°), PI (61.7° vs. 49.8°), STA (95.4° vs. 101.8°), and SK (31.0° vs. 23.7°). Based on the logistic regression analysis, only PI (odds ratio [OR], 1.074; 95% CI, 1.026–1.124) and STA (OR, 0.822; 95% CI, 0.734–0.920) remained significant predictors for the presence of spondylolysis. In the spondylolysis group, PI correlated significantly with PTH (r=−0.589), FSPA (r=0.880), and SK (r=0.576), whereas in the normal group, PI correlated significantly with FSPA (r=0.781) and SK (r=0.728).ConclusionsBy simultaneously assessing multiple sacropelvic parameters, we associated increasing PI with L5 spondylolysis. Decreasing STA, which likely represents a chronic remodeling secondary to spondylolysis, was also associated with increased risk. Back pain in an adolescent or young adult with high PI or low STA should raise suspicion of a possible occult spondylolysis.

Revisiting thoracic kyphosis: a normative description of the thoracic sagittal curve in an asymptomatic population.

Thoracic kyphosis (TK) remained in the shadow of lumbar lordosis. Based on Berthonnaud and Roussouly segmentation, TK is divided into two arches: upper TK (UTK) and lower TK (LTK). The purpose of this study is to propose a normative description of the TK arches in an asymptomatic adults' population and their correlation with spinal and pelvic parameters. This is an observational study performed on asymptomatic healthy Caucasians volunteers aged between 18 and 45years. Each patient had a standardized standing biplanar full spine X-rays. Using KEOPS®, sacropelvic parameters and global spinal parameters (LL, TK) as well as the inflexion point location were measured. The upper lumbar lordosis angle (ULL) as well as LTK and UTK was calculated. Patients were classified according to Roussouly morphotypes of normal spine. A total of 373 adults (F/M = 1.4/1) were enrolled with mean age of 27years. Mean UTK averaged 25.8°, while mean LTK averaged 19.8° (p < 0.001). UTK angle values were statistically the same in the five different Roussouly spinal shapes (p > 0.05), while LTK values were variable among different Roussouly spine subtypes (p < 0.05). Finally, TK showed the highest correlation with the LL mainly with the ULL (Pearson = 0.66). In asymptomatic young adults, thoracic kyphosis is composed by two unequal arches, a stable UTK and a variable LTK, with an apex around T8 and T9 vertebra, depending on the spinal morphotype according to Roussouly classification. This should be taken into consideration when analyzing spine sagittal compensation and preparing corrections to minimize risk of mechanical complications.

Relationship of aortic bifurcation with sacropelvic anatomy: Application to anterior lumbar interbody fusion.

Various sacropelvic parameters such as the pelvic Incidence (PI) are used to predict ideal lumbar lordosis and aid surgical planning. The objective of this study was to establish the relationship between the location of the aortic bifurcation from the sacral promontory and sacropelvic measures including the PI. One hundred sixty five computed tomography (CT) scans obtained for major trauma including the entire spine were identified. Sacropelvic parameters including PI, sacral anatomic orientation, pelvic thickness (PTH), and sacral table angle were measured. Aortic bifurcation was identified on sagittal and coronal imaging and the distance from the sacral promontory (bifurcation-promontory distance [BPD]) measured (mm). Mean age of the cohort was 44.3 years (SD 18.5; range 16-88 years); 61.8% male. The mean PI was 49.2° (SD 10.2°; range 30°-80°). The mean BPD was 66.4 mm (SD 13.1 mm; range 38.3-100 mm). In the majority, the bifurcation was at the level of the L4 vertebral body (72.7%). Only age (r = -.389; p < .0001) and PTH (r = .172; p = .027) correlated with the BPD to a significant degree. PI did not correlate with BPD (r = .061; p = .435). Linear regression analysis provided the following predictive equation: BPD = 34.3 mm + 0.30 × PTH. This study demonstrates a lack of any meaningful correlation between sagittal pelvic parameters and the distance of the aortic bifurcation from the sacral promontory. Surgical planning for fusion surgery in the lumbar spine should include assessment of spinopelvic parameters and if anterior access to the lumbar disc(s) necessary, vascular anatomy should be carefully assessed independent of these measures.

Computed tomography analysis of sacropelvic parameters in relation to anterior access to the lumbosacral disc

Purpose: Anecdotally a higher pelvic incidence (PI) confers a ‘deeper’ pelvis with the potential for challenging access, yet this is ill-defined in the existing literature. The aim of this study was to assess the relationship of sacropelvic sagittal parameters and their relationship with the projection angle (PA), an indicator of access to and orientation of the lumbosacral disc with respect to the pelvis and identify a threshold PI value beyond which more difficult surgical access may be anticipated.Materials and methods: Computed tomography (CT) scans taken for trauma were studied. Measures including the PI, sacral kyphosis (SK), sacral table angle (STA), PA and anterior pelvic angle (APA) were taken. The PA is the angle subtended by a line from the apex of the pubic symphysis to the sacral promontory and a line running along the sacral endplate. A positive value is obtained when the line from the endplate runs superior to the symphysis.Results: 168 scans were reviewed, mean age 44.2 years (s.d. 18.4). The mean PI was 50.0 (s.d. 10.2), SK 24.4 (s.d. 12.3), and STA 102.0 (s.d. 6.1). The mean PA was 20.1 (range −14 to 46; s.d. 10.3). PA correlated with PI (R = −0.892; p < .001) and also SK (R = −0.760; p < .001). With PI values above 73 the PA is likely to be negative with the lumbosacral disc orientation falling behind the pubic symphysis. One-way analysis of variance showed differences in PA according the six subclasses of PI.Conclusion: The PA, as an indicator of the orientation of the lumbosacral disc with respect to the pelvis, correlated strongly with the PI. Patients with high PI are more likely to have a lumbosacral disc with trajectory falling behind the pubic symphysis and surgeons should closely analyse pelvic anatomy, particularly in patients with high PI.

Pelvic Incidence: Computed Tomography Study Evaluating Correlation with Sagittal Sacropelvic Parameters.

Normal values for spinal alignment are often based on the pelvic incidence (PI), defined as the angle subtended by a line from the bicoxofemoral axis to the midpoint of the sacral endplate and a line perpendicular to the midpoint. Despite widespread use, determinants of its values remain obscure. The aim of this study was to determine correlation of sacropelvic parameters with the PI on computed tomography (CT). CT scans performed for trauma were identified over a 1-year period. Patients aged over 16 were included. PI, sacral anatomic orientation, sacral table angle (STA), sacral kyphosis (SK), pelvic thickness (PTH), femorosacral pelvic angle, pelvisacral angle, and sacropelvic angle were measured. Additional novel measures including crest-to-pubis distance, crest-to-sacrum distance (CSD), inlet distance, outlet distance, and inlet-outlet angle were taken. One hundred and seventy-seven scans were analyzed. Mean age 44.3 years; 62% male. The mean PI was 50.1 (SD 10.8; range 29-87). SK (r = 0.769), inlet-outlet angle (r = -0.533), PTH (r = -0.370), CSD (r = 0.290), and STA (r = -0.276) significantly correlated with PI. Multivariate analysis developed a predictive equation of: PI = 101.45 - (0.52 × STA) + (0.67 × SK) - (0.34 × inlet-outlet angle), with an adjusted R2 0.734 (P < 0.001). Measures that represent the sacral morphology, particularly SK, and the position of the sacrum in space correlated strongly with the PI and contributed strongly to a predictive equation. These findings may direct further efforts to explore how the PI is determined and therefore how it may be modified. Clin. Anat. 33:237-244, 2020. © 2019 Wiley Periodicals, Inc.

Reciprocal Changes in Sagittal Alignment in Adolescent Idiopathic Scoliosis Patients Following Strategic Pedicle Screw Fixation.

Study DesignRetrospective observational study.PurposeTo analyze the effect of low-density (LD) strategic pedicle screw fixation on the correction of coronal and sagittal parameters in adolescent idiopathic scoliosis (AIS) patients.Overview of LiteratureLD screw fixation achieves favorable coronal correction, but its effect on sagittal parameters is not well established. AIS is often associated with decreased thoracic kyphosis (TK), and the use of multi-level pedicle screws may result in further flattening of the sagittal profile.MethodsA retrospective analysis was performed on 92 patients with AIS to compare coronal and sagittal parameters preoperatively and at 2-year follow-up. All patients underwent posterior correction via LD strategic pedicle screw fixation. Radiographs were analyzed for primary Cobb angle (PCA), coronal imbalance, cervical sagittal angle (CSA), TK, lumbar lordosis (LL), pelvic incidence, pelvic tilt (PT), sacral slope (SS), C7 plumb line, spino-sacral angle, curve flexibility, and screw density.ResultsPCA changed significantly from 57.6°±13.9° to 19°±8.4° (p <0.0001) with 67% correction, where the mean curve flexibility was 41% and screw density was 68%. Regional sagittal parameters did not change significantly, including CSA (from 10.76° to 10.56°, p =0.893), TK (from 24.4° to 22.8°, p =0.145), and LL (from 50.3° to 51.1°, p =0.415). However, subgroup analysis of the hypokyphosis group (<10°) and the hyperkyphosis group (>40°) showed significant correction of TK (p <0.0001 in both). Sacro-pelvic parameters showed a significant decrease of PT and increase of SS, suggesting a reduction in pelvic retroversion SS (from 37° to 40°, p =0.0001) and PT (from 15° to 14°, p =0.025).ConclusionsLD strategic pedicle screw fixation provides favorable coronal correction and improves overall sagittal sacro-pelvic parameters. This technique does not cause significant flattening of TK and results in a favorable restoration of TK in patients with hypokyphosis or hyperkyphosis.

Combination of whole-spine lateral radiograph and lateral scanogram in the assessment of global sagittal balance

Background ContextGlobal balance of human standing is analyzed as the geometric sum of the individual alignments extending from the spinal column to the pelvis, and to the lower limbs. The innovative EOS system has opened new perspectives for the global analysis of whole-body alignment, but its use is very limited because of its high cost. An alternative may be to combine the whole-spine lateral radiograph and the lateral scanogram in the global sagittal analysis of whole-body alignment. PurposeWe examined to determine the validity and reliability of a lateral scanogram in the measurement of sacropelvic parameters. Study Design/SettingA retrospective radiological study was carried out. Patient SampleWe randomly selected 100 sets of digital radiographs, both whole-spine radiographs and lower-limb scanograms, from our database. Outcome MeasuresSacropelvic parameters, including pelvic incidence, sacral slope, and pelvic tilt, were measured on both whole-spine radiographs and lower-limb scanograms by three independent examiners on three separate occasions. MethodsAgreement regarding the measurements on both image types was calculated to assess the validity of the lateral scanogram for use in whole-body alignment determinations. Intraobserver and interobserver reliabilities among the types of measurements were calculated. ResultsThe sacropelvic area on the lateral scanogram was not visible in 19 patients (19%). In the remaining 81 patients, the sacropelvic parameters on the lateral scanogram were similar to those on the whole-spine lateral radiograph (Pearson correlation coefficient, 0.764–0.805). Intraobserver and interobserver reproducibilities for both modalities were good to excellent (intraclass correlation coefficient, 0.657–0.984). ConclusionsSacropelvic parameter measurements on lateral scanogram were reliable and were similar to those measured on whole-spine lateral radiograph. Thus, global alignment can be evaluated using the lateral scanogram in combination with the whole-spine lateral radiograph.

Radiographic Analysis of the Sacropelvic Parameters of the Spine and Their Correlation in Normal Asymptomatic Subjects

Study Design Cross-sectional study. Objective Sacropelvic parameters in various spine and hip disorders have been published in various studies. We aimed to study the normal sacropelvic parameters and curvatures of the spine and their correlation in asymptomatic Indian adults in relation to variations in sex and age. Methods The study included 101 asymptomatic adults (50 men and 51 women with an average age of 47.16 and 48.59 years, respectively). For each subject, the thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were measured from standing lateral radiographs. After stratification of the group by sex and age with a cutoff of 50 years, descriptive, correlation, and regression analysis were performed using SPSS software. Results The average PI, SS, PT, LL, and TK values were 55.48 (±5.31), 35.99 (±7.53), 17.97 (±7.16), 48.84 (±9.82), and 32.55 (±10.92), respectively. No statistically significant difference was observed in these values with regards to sex and age < 50 years and > 50 years but the pelvic incidence was found to be higher in women. A positive correlation between the PI and SS and a negative correlation between the SS and PT was observed. A positive correlation between the TK and LL was found in subjects > 50 years. Simple and multiple regression analyses were also performed for different groups. Conclusion The current study is the first of asymptomatic Indian adults and provides invaluable information to the clinicians about the normal range of sacropelvic and spinopelvic parameters, which is useful to plan spinal deformity corrections and to evaluate pathologic conditions associated with abnormal angular values.

The biomechanical effects of spinal fusion on the sacral loading in adolescent idiopathic scoliosis

BackgroundPosterior spinal surgical correction is performed to correct spinal deformities in adolescent idiopathic scoliosis. Althoughthe relative spino-pelvic alignment changes after spinal surgery, pelvis remains unfused in idiopathic scoliosis surgery. The impact of the spinal fusion on the transferred load to the pelvis via sacrum is not documented in the scoliotic subgroups. MethodBi-planar radiographs of 9 scoliotic subjects before and in average 16months after spinal instrumentation surgery, and 12 controls were selected retrospectively. Patient-specific 3D reconstruction and finite element models of the spine, ribcage, and pelvis were developed. Spinal parameters (Cobb angles, kyphosis, lordosis), sacro-pelvic parameters (pelvic incidence, pelvic tilt, sacral slope), frontal and sagittal balances, the position of the trunk center of mass, and the centroid of the stress distribution on the sacrum superior endplate were measured and computed before operation and in the last follow-up. FindingsThe position of the stress distribution centroid on the sacrum superior endplate with respect to the central hip vertical axis was significantly different between pre-operative and post-operative patients p<0.05. The distance between the anterior–posterior position of the trunk center of mass and thecenter of pressure on the superior sacral endplate significantly decreased after the spinal surgery p<0.05. InterpretationThe impact of the scoliosis spinal fusion on the transferred load between the spine and pelvis was evaluated. The biomechanical loading of the sacrum endplate was related to the post-operative postural balance and compensatory changes in the spino-pelvic alignment after scoliosis surgery.

Minimally Invasive Transforaminal Lumbar Interbody Fusion for Spondylolisthesis: Comparison Between Isthmic and Degenerative Spondylolisthesis

Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a common surgical option for degenerative spondylolisthesis (DS). However, its effectiveness for isthmic spondylolisthesis (IS) is still controversial. No current studies have directly compared perioperative and postoperative results including various radiological parameters between IS and DS after MIS TLIF. The purpose of this study is to compare the clinical and radiological results between isthmic and degenerative spondylolisthesis after MIS TLIF. This is a retrospective study of 41 patients who underwent MIS TLIF for single-segment, grade 1 or 2 IS (n = 18) and DS (n = 23). The same surgical techniques and procedure were applied to both groups. Perioperative outcomes (operation time, blood loss, hospital stay, complications); clinical outcomes (visual analog scale [VAS], Oswestry Disability Index [ODI]); radiological parameters (disk height, degree of spondylolisthesis, slip angle, lumbar lordosis, segmental lordosis, sacropelvic parameters: pelvic incidence, sacral slope, pelvic tile); and fusion rates using computed tomography scanning were compared between groups at 1 year postoperatively. There were no significantly different perioperative results between groups. Mean VAS and ODI scores improved significantly postoperatively in both groups but were not significantly different between groups at each follow-up point. Radiological parameters were not significantly different between groups except disk height and degree of spondylolisthesis. The disk heights were increased postoperatively (IS: 6.79-9.22 mm; DS: 8.18-8.97 mm) in both groups, and there were significant differences preoperatively. In addition, disk height restoration was greater for IS than DS (2.43 mm vs. 0.79 mm, P = 0.01). However, postoperative disk heights were not significantly different between groups. The degree of spondylolisthesis was significantly different between groups both preoperatively (16.77% vs. 11.33%, P < 0.01) and postoperatively (9.79% vs. 3.78%, P < 0.01). However, slip reduction was no different between groups (6.97 vs. 7.56%, P = 0.74). Fusion rates were not significantly different between groups. MIS TLIF resulted in similar clinical outcomes when used to treat both isthmic and degenerative spondylolisthesis. Although disk height restoration was more effective for IS than DS, other radiological parameters including fusion rate were no different between groups. For both isthmic and degenerative spondylolisthesis, MIS TLIF can be a safe and effective surgical option.

Bilateral tubular minimally invasive surgery for low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS): analysis of a series focusing on postoperative sagittal balance and review of the literature.

To report our early experience with minimally invasive surgery (MIS) in low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS), and to analyze the impact of surgery on postoperative spino-pelvic and sacro-pelvic parameters. Eight patients (mean age 47.6years) underwent MIS for LDLLS involving in all but one the L5-S1 level. VAS and ODI were used for clinical assessment. Imaging included pre-operative X-rays, CT and MRI scans. Post-operatively, all patients underwent X-rays and CT-scans. Pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) values as well as lumbar lordosis (LL) have been derived from pre- and post-operative standard X-rays. Mean follow-up is 30.12months (range 15-42). No complications related to the surgical procedure were observed. Patients reported a satisfactory clinical outcome, as demonstrated by variation in mean VAS (from 9.1 to 3.6) and ODI (from 70.50 to 28.25%) scores. Comparison between pre- and post-operative sacro-pelvic parameters documented moderate changes, with reduction of PT and increase of SS in all but one patient. Overall sagittal balance of the spine has been evaluated using the sagittal vertical axis (SVA), obtained from post-operative X-rays. Mean value of SVA demonstrated a good sagittal balance of the spine. This series demonstrates that MIS is feasible and effective for LDLLS, as witnesses by the satisfactory clinical results maintained at medium-term follow-up. We submit that TLIF is a valid option but an adequately sized and positioned interbody cage is a key factor to allow satisfactory restoration of segmental lordosis.

Three-Dimensional Spinopelvic Relative Alignment in Adolescent Idiopathic Scoliosis

Three-dimensional (3D) analysis of the spinopelvic alignment in adolescent idiopathic scoliosis (AIS). To study the 3D pelvic alignment with respect to the spinal deformities in AIS subgroups. Spinopelvic alignment is subject to change in scoliosis. Many sacropelvic parameters were developed to characterize spinopelvic alignment in the sagittal plane. However, not much is known about the 3D pelvic alignment with respect to the thoracic and lumbar spinal deformities in AIS. Eighty AIS subjects with right main thoracic (MT), 80 AIS with left thoracolumbar/lumbar (TL/L) curves, and 35 asymptomatic controls were included. Thoracic and lumbar Cobb angles, kyphosis, lordosis, pelvic incidence, pelvic tilt, and sacral slope were measured. Pelvic tilt and axial rotation in the coronal and transverse planes, respectively, were computed using the ipsilateral anterior superior iliac spine and posterior superior iliac spine positions. Leg length discrepancy was determined by the vertical difference in the position of the center of the femoral heads in the coronal plane. In 59% of the MT subjects and 79% of the TL/L subjects in the erect position, the pelvis was tilted toward the convex side of the major curve in the coronal plane. The direction of the pelvic axial rotation in the transverse plane was in the same direction as the MT apical vertebra rotation in 84% of the MT subjects and 55% of the TL/L group. The pelvic incidence correlated to the lumbar lordosis in AIS (r = 0.41, P < 0.001). Pelvic coronal tilt correlated significantly to the leg length discrepancy in MT (r = 0.67) and TL/L (r = 0.61) subjects (P < 0.001). Novel pelvic parameters were introduced to characterize the spinopelvic relative alignment in scoliotic subgroups. The proposed method related the orientation of the pelvis in the coronal and transverse planes to both thoracic and lumbar spinal deformities.

Correlation of Sacropelvic Geometry With Disc Degeneration in Spondylolytic Cadaver Specimens

An anatomic study of sacral inclination, pelvic incidence, pelvic lordosis, and disc degeneration in cadaveric lumbar spines. To evaluate the relationship between sacropelvic parameters and disc degeneration in subjects with bilateral spondylolysis at L5. L5-S1 disc degeneration is greater in patients with spondylolytic defects (L5-S1) than with an intact pars interarticularis secondary to the instability caused by spondylolysis. Sacral inclination, pelvic incidence, and pelvic lordosis affect sagittal balance and axial forces on the L5-S1 disc. An observational study was performed on 120 cadaveric specimens with spondylolysis (L5-S1) identified of 3100 total cadaveric specimens. Nine specimens were excluded because of incomplete or degraded skeletal elements; 10 were excluded for having unilateral defects only. The specimens were evaluated for sacral inclination, pelvic incidence, and pelvic lordosis. Disc degeneration and facet arthrosis at L4-L5 and L5-S1 were measured by the classification of Eubanks et al. Linear regression analyses were then used to determine the relationship between sacropelvic parameters and degeneration at the L5-S1 segment, correcting for confounding factors such as age, sex, and race. Linear regression demonstrated a significant association between sacral inclination and disc degeneration at L5-S1 (P = 0.018). Specimens were then divided into two groups, those in the highest quarter of pelvic incidence, and the remainder. Spearman rank correlation demonstrated a significant association between disc degeneration at L5-S1 and the highest quarter of pelvic incidence (P = 0.017). Increasing pelvic lordosis was also associated with an increase in facet arthrosis at L4-L5 (P = 0.006). The findings of this study show a relationship between the sacropelvic geometry and the degree of L5-S1 disc degeneration as well as L4-L5 facet degeneration in spondylolytic specimens. This relationship may prove useful in predicting the course of disc degeneration in patients with spondylolysis.