Influence of age and sagittal balance of the spine on the value of the pelvic incidence

Pelvic parameters as prognostic factors of radiographic progression in classical Ankylosing Spondylitis: A prospective follow-up data

Radiographic progression in Ankylosing spondylitis (AS) is driven by mechanical strain. A well-balanced spine provides a favorable weight distribution across the entheses. Pelvic parameters are useful in assessing the shape of the spine. The present study aimed to prospectively investigate the predictive value of pelvic parameters for radiographic progression in AS. This non-interventional, observational, and prospective study enrolled AS patients fulfilling the modified New York criteria (mNY) currently under follow-up in the MARS (MARmara Spondyloarthritis) outpatient clinics. The primary objective was to investigate the relationship between the baseline pelvic parameters and radiographic progression in the spine. Two trained radiologists (EB, OB) independently assessed the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). An orthopedic surgeon (AHA) and a radiologist (EB) derived the pelvic parameters. Patients with no bridging or bamboo spine were included in the final analysis. Risk assessment for radiographic progression, defined as a two-unit increase in mSASSS or developing a new syndesmophyte every two years, was done using uni- and multivariate logistic regression analyses. Radiographs of 69 AS patients were analyzed. The median (IQR 25-75) prospective follow-up was 47.7 (34.6-52.8) months. Only 33.3% (23/69) had radiographic progression. The pelvic tilt (PT) was lower in patients with radiographic progression (p = 0.037) and each degree of decrease in PT provided a 9% increase in risk for radiographic progression. Male patients were 7.5 times more likely to progress. Pelvic parameters provide a prognostic insight into the radiographic progression in AS. Our observations may aid in selecting patient-specific interventions in addition to anti-inflammatory treatments.

Incidence and risk factors of new-onset sacroiliac joint pain after spinal surgery: a systematic review and meta-analysis

Purpose

A systematic review and meta-analysis for incidence and risk factors of new-onset sacroiliac joint pain (SIJP) after spinal surgery aimed to provide evidence-based medical references for its early prevention, timely intervention, and appropriate treatment.

Methodology

The protocol of the systematic review and meta-analysis was registered in the International Prospective Register of Systematic Review (PROSPERO) with the PROSPERO ID (CRD42023463177). Relevant studies were searched to January 2024 from the databases of PubMed, Embase, Cochrane Library, and Web of Science, and the types of studies were cohort studies, case-control studies, and cross-sectional studies. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) and the Cross-Sectional/Prevalence Study Quality recommended by the Agency for Healthcare Research and Quality (AHRQ). Two authors conducted studies search, data extraction, and quality assessment independently. Meta-analyses were done using Stata 14.0 software.

Results

Twelve observational studies with 3,570 spinal surgery patients were included. Ten were case-control studies, one was a cross-sectional study, and another was a cohort study, all of which were of moderate quality and above. The results of the meta-analysis showed that the incidence of new-onset SIJP after spinal surgery was 9.40%; females, no. of surgical segments, fusion to the sacrum, and postoperative pelvic tilt (PT) were significantly associated with the new-onset SIJP after spinal surgery. Meta-analyses for preoperative and postoperative controls of spondylopelvic parameters showed that postoperative lumbar lordosis (LL) in the SIJP group and postoperative LL and sacral slope (SS) of patients in the NoSIJP group had significant differences from preoperative.

Conclusion

Available evidence suggests that an increased risk of new-onset SIJP after spinal surgery is associated with sex, multi-segmental surgery, fusion to the sacrum, and greater postoperative PT.

Variation of Odontoid Incidence According to Age in Asymptomatic Children

OBJECTIVE

To investigate the effect of age and sex on odontoid parameters and their relationships with cervical sagittal alignment in children.

METHODS

A total of 155 Chinese children without cervical symptoms were divided into groups by age: 3-12 years (87 participants), 13-18 years (68 participants), and sex: male (91 participants) and female (64 participants). Lateral plain radiographs of the whole spine were analyzed for (1) odontoid parameters: odontoid incidence (OI), odontoid tilt, and C2 slope (C2S); and (2) cervical sagittal parameters: C0-2, C2-3, C2-4, C2-5, C2-6, and C2-7 angles (cervical lordosis [CL]), T1 slope (T1S), and T1S minus CL (T1S-CL). Student's t-tests, linear regression analyses, and Pearson's correlation coefficient analyses were performed.

RESULTS

OI showed a significant difference between the 3-12 and 13-18 year groups (13.35°±4.32° vs. 17.21°±4.26°, P<0.001), and significant differences were also observed in odontoid tilt (P=0.001) and C2S (P<0.001) between different sexes. Positive correlations were found between age and OI in the 3-12 and 13-18 year groups (adjusted R2=0.104 and 0.048, respectively). OI and C2S were positively correlated with the C0-2 angle in all age and sex groups.

CONCLUSIONS

Age emerged as a critical determinant of OI, which increased with age among pediatric populations. Clinicians should carefully consider the disparity in OI during the assessment and restoration of cervical sagittal balance in children.

Morphological features of lower lumbar degenerative kyphosis

PURPOSE

Kyphosis in the lower lumbar spine (L4-S1) significantly affects sagittal alignment. However, the characteristics of the spinopelvic parameters and compensatory mechanisms in patients with lower lumbar degenerative kyphosis (LLDK) have not been described in detail. The objective of this retrospective study was to analyze the morphological characteristics in patients with sagittal imbalance due to LLDK.

METHODS

In this retrospective study, we reviewed the clinical records of consecutive patients who underwent corrective surgery for adult spinal deformity (ASD) at a single institution. We defined LLDK as (i) kyphotic deformity in lower lumbar spine (L4-S1) or (ii) inappropriate distribution of lordosis (lordosis distribution index < 40%) in the lower lumbar spine. Global spine parameters of ASD patients and MRI findings were compared between those with LLDK (LLDK group) and without LLDK (control group).

RESULTS

A total of 95 patients were enrolled in this study, of which the LLDK group included 14 patients (14.7%). Compared to the control, LLDK presented significantly higher pelvic incidence (62.1° vs 52.6°) and pelvic tilt (40.0° vs 33.4°), larger lordosis at the thoracolumbar junction (12.0° vs -19.6°), and smaller thoracic kyphosis (9.3° vs 26.0°). In LLDK, there was significantly less disc degeneration at L2/3 and L3/4.

CONCLUSION

LLDK patients had high pelvic incidence, large pelvic tilt, and a long compensatory curve at the thoracolumbar junction and thoracic spine region.

Relationship between paravertebral muscle function, pelvic incidence, and health-related quality of life in patients with degenerative spinal deformity

BACKGROUND

Patients with degenerative spinal deformity often experience symptoms that seriously affect their quality of life, such as low back pain and dysfunction. This study aimed to investigate the relationship between paravertebral muscle function and pelvic incidence (PI) and their effect on health-related quality of life (HRQL) in patients with degenerative spinal deformity.

METHODS

A total of 112 patients with degenerative spinal deformity in Southwest Hospital (Chongqing, China) were enrolled. They were divided into groups according to PI angle: high (PI > 60°, n = 37), normal (PI 50°-60°, n = 31), and low (PI < 50°, n = 44). Paravertebral muscle strength and endurance were assessed using the prone external fixation test frame. The sagittal vertical axis (SVA) was measured on X-rays of the spine in an anterolateral position, and all subjects were assessed with the Oswestry Disability Index (ODI), Roland-Morris questionnaire (RMQ), and 36-Item Short Form Health Survey (SF-36). Pearson or Spearman coefficients were used to assess the relationship of paravertebral muscle function with SVA, PI, and health-related quality of life.

RESULTS

Maximal voluntary exercise (MVE) in the high-PI group was significantly lower than the MVE of both the normal- and low-PI groups (p < 0.05). There was no significant difference in MVE between the normal- and low-PI groups (p > 0.05). There was no significant difference in endurance time, SVA, ODI, RMQ, and SF-36 among the three groups. Paravertebral muscle MVE was negatively correlated with PI, SVA, ODI, and RMQ (r = - 0.193, - 0.210, - 0.283, - 0.277, p < 0.05). Endurance time of paravertebral muscle was also negatively correlated with SVA, ODI, and RMQ (r =  - 0.200, - 0.420, - 0.348, p < 0.05) and positively correlated with SF-36 (r = 0.245, p < 0.05). In addition, paravertebral muscle MVE was positively correlated with the physical functioning score of the SF-36 (r = 0.251, p < 0.05), and the endurance time of paravertebral muscle was positively correlated with the physical functioning, physical role, bodily pain, and social function scores of the SF-36 (r = 0.342, 0.230, 0.209, 0.256, p < 0.05).

CONCLUSIONS

High PI may serve as a risk factor for decreased paraspinal muscle strength in patients with degenerative spinal deformities. Early and targeted exercises focusing on paraspinal muscle strength and endurance could potentially be of positive significance in slowing down the progression of sagittal imbalance, alleviating functional disorders, and increasing health-related quality of life in patients with degenerative spinal deformity.

Can Pelvic Incidence Change After Lumbo-Pelvic Fixation for Adult Spine Deformity, and Would the Change be Affected by the Type of Pelvic Fixation?

STUDY DESIGN

Retrospective review.

OBJECTIVE

To assess the change in pelvic incidence (PI) after lumbo-pelvic fixation and the differential impact of the type of pelvic fixation: S2-alar-iliac screws (S2AI) versus Iliac screws (IS) on postoperative PI.

SUMMARY OF BACKGROUND DATA

Recent studies suggest that changes occur to the previously assumed fixed PI after spino-pelvic fixation.

METHODS

Adult spine deformity (ASD) patients who underwent spino-pelvic fixation with≥4 levels of fusion were included. Preoperative and postoperative PI, lumbar lordosis (LL), thoracic kyphosis, pelvic tilt, sacral slope, PI-LL mismatch, and the Sagittal Vertical Axis (SVA) were analyzed on EOS imaging. A significant PI change was established at≥6°. Patients were categorized based on the type of pelvic fixation (S2AI vs. IS).

RESULTS

One-hundred-forty-nine patients were included. Of these, 77(52%) had a>6° change in their PI postoperatively. In patients with high preoperative PI (>60°), 62% had a significant PI change compared with 33% of patients with normal PI (40°-60°) and 53% in patients with low PI (<40°; P =0.01). PI was likely to decrease in patients with high baseline PI (>60°) and to increase in patients with low baseline PI (<40°). Patients with a significant PI change had a higher PI-LL. Patients in the S2AI group (n=99) and those in the IS group (n=50) were comparable at baseline. In the S2AI group, 50 (51%) patients had>6° change in their PI compared with 27(54%) patients in the IS group( P =0.65). In both groups, patients with high preoperative PI were more prone to significant postoperative changes ( P =0.02 in IS, P =0.01 in S2AI).

CONCLUSION

PI changed significantly in 50% of patients postoperatively, especially in those with high/low preoperative PI and those with severe baseline sagittal imbalance. This occurs similarly in patients with S2AI and those with IS screws. Surgeons should keep in mind these anticipated changes while planning ideal LL, as this impacts postoperative PI-LL mismatch.

LEVEL OF EVIDENCE

4.

Association between posterior tibial slope and anatomic spinopelvic parameters: a retrospective cross-sectional study

PURPOSE

Only a few publications considered the influence of the spinopelvic parameters on below-hip anatomy. There is a lack of evidence about the relationship between the anatomic spinopelvic parameters and the posterior tibial slope (PTS). Therefore, the aim of this study was to analyze the association between fixed anatomic spinopelvic parameters and PTS.

METHODS

Adult patients presenting with lumbar, thoracic, or cervical complaints together with knee pain at a single hospital between 2017 to 2022 with available standing full-spine lateral radiograph and lateral knee radiograph were retrospectively reviewed. The measured parameters included the pelvic incidence (PI), the sacral kyphosis (SK), the pelvisacral angle, the sacral anatomic orientation (SAO), the sacral table angle, the sacropelvic angle and the PTS. Pearson's correlations and linear regression analyses were conducted.

RESULTS

A total of 80 patients (44 women), median age 63 years were analyzed. A strong positive correlation was identified between PI and PTS (r = 0.70, p < 0.001). A strong negative correlation was observed between PI and SAO (r = - 0.74, p < 0.001). A strong positive correlation was observed between PI and SK (r = 0.81, p < 0.001). A univariable linear regression analysis showed that PTS can be deduced from PI according to the following formula: PTS = 0.174 × PI - 1.138.

CONCLUSION

This study is the first to support a positive correlation between the PI and the PTS. We demonstrate that knee anatomy is individually correlated to pelvic shape and therefore influences spinal posture.

How Does Spino-Pelvic Fixation Affect Post-Operative Compensatory Mechanisms in Adult Spinal Deformity?

STUDY DESIGN

Retrospective single-center multi-surgeon cohort study.

OBJECTIVES

Compare the post-operative changes in the compensatory mechanisms of the sagittal balance according to the type of pelvic fixation: S2-Alar-iliac screws (S2AI) vs iliac screws (IS) in patients with Adult spine deformity (ASD).

METHODS

ASD patients who underwent spino-pelvic fixation and remained with a PI-LL >10° mismatch post-operatively were included. Pre-operative and 1-year-follow-up PI, Lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), thoracic kyphosis (TK), femur obliquity angle (FOA), knee flexion angle (KFA) and ankle flexion angle (AFA) were analyzed on EOS imaging. Patients were categorized based on their pelvic fixation type (S2AI vs IS), and the pre-operative to 1-year-post-operative changes (ΔX°) in the compensatory mechanisms were compared between groups.

RESULTS

Patients with S2AI (n = 53) and those with IS (n = 26) screws were comparable at baseline. ΔSS averaged 9.87° in the S2AI compared to 13.2° in the IS (P = .001), whereas the ΔKFA reached 6.01° in the S2AI as opposed to 3.06° in the IS (P = .02). The ΔPT was comparable between both groups (6.35°[S2AI group] vs 5.21°[ISgroup], P = .42). ΔTK, ΔLL, ΔFOA and ΔAFA were comparable between both groups.

CONCLUSION

The type of pelvic fixation impacts significantly the post-operative compensatory mechanisms in patients with ASD. Patients with S2AI screws are more likely to compensate their remaining post-operative PI-LL mismatch through their knees and less likely through their pelvis compared to patients with IS, despite similar changes in PT. This could be explained by an increased SI joint laxity in ASD patient and the lower resistance of the iliac connectors to the junctional mechanical stresses, allowing for sacro-iliac joint motion in patients with IS.

Correlation between strength/endurance of paraspinal muscles and sagittal parameters in patients with degenerative spinal deformity

BACKGROUND

Sagittal imbalance is a common cause of low back pain and dysfunction in patients with degenerative spinal deformity (DSD), which greatly affects their quality of life. Strength and endurance are important functional physical indexes for assessing muscle condition. However, the correlation between sagittal parameters and paraspinal muscle strength/endurance is not yet clear. The purpose of this study was to analyze the correlation between strength/endurance of paraspinal muscles and sagittal parameters in patients with DSD.

METHODS

There were 105 patients with DSD and 52 healthy volunteers (control group) enrolled. They were divided into the balance group [sagittal vertical axis (SVA) < 5 cm, n = 68] and imbalance group (SVA ≥ 5 cm, n = 37). The maximal voluntary exertion (MVE)/Endurance time (ET) of paravertebral muscles were assessed using the prone position test stand, and the sagittal parameters of the subjects were measured, namely, SVA, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). Pearson coefficients were used to assess the correlation between paraspinal muscle MVE/ET and sagittal parameters.

RESULTS

MVE and ET of paravertebral muscles in the control group were significantly higher than those in the balance and imbalance groups (P < 0.05), whereas MVE in the balance group was significantly higher than that in the imbalance group (P < 0.05). SVA in the imbalance group was significantly higher than those in the control and balance groups (P < 0.05). SS and TK in the control group were significantly higher than those in the imbalance group (P < 0.05), and PT and PI in the control group were significantly lower than those in the balance and imbalance groups (P < 0.05). LL in the imbalance group was significantly lower than that in the balance and control groups (P < 0.05). MVE, MVE/BH, and MVE/BW of paraspinal muscles in the imbalance group were negatively correlated with SVA and PT. Moreover, they were positively correlated with LL.

CONCLUSIONS

Deformity may cause the decrease of MVE and ET of paraspinal muscles in the prone position in patients with DSD. Furthermore, the decline in MVE of paraspinal muscles may be a predisposing factor for the imbalance observed. The decrease of MVE/BW of paraspinal muscles may be involved in spinal compensation, and it is a sensitive indicator for sagittal imbalance and lumbar lordosis.

Age, pelvic incidence, facet joint angle and pedicle-facet angle as correlative factors for isthmic spondylolisthesis: a retrospective case control study

BACKGROUND

Isthmic spondylolisthesis (IS) is a common clinical disease with a high incidence rate. However, most current researches explain the clear pathogenesis from a single perspective. The aim of our study was to explore the relationships between multiple parameters in patients and find the potential risk factors of this disease.

METHODS

Our study retrospectively included 115 patients who were diagnosed with isthmic spondylolisthesis and the same number of individuals without spondylolisthesis. The following parameters were measured or collected: age, pelvic incidence (PI), facet joint angle (FJA) and pedicle-facet angle (P-F angle). The radiographic files were imported into Mimics Medical 20.0 and all collected data were analyzed using SPSS, version 26.0, statistical software.

RESULTS

The age was higher in IS group than in control group. PI was also higher in the IS group (50.99 ± 7.67) than in the control group (43.77 ± 9.30) significantly (P = 0.009). There was significant difference in cranial and average FJA tropism in L3-L4 level (P = 0.002, P = 0.006, respectively) and in L4-L5 level (P < 0.001). P-F angle of L4-L5 level showed significantly larger in IS group than in control group (P = 0.007).The logistic regression analysis showed a larger age, a greater L3-L4 cranial FJA tropism, and a greater L4-L5 cranial FJA tropism were potential predictors of IS, with an OR of 1.07, 1.28, and 1.39 respectively. The thresholds of the predictors were 60 years, 5.67°, and 8.97° according to the ROC curve. The linear regression equation was established: degree of slippage (%) = 0.220*age - 0.327* L3-4 cranial FJA tropism - 0.346* L4-5 average FJA tropism (F = 3.460, P = 0.011, r = 0.659).

CONCLUSIONS

Our study revealed that isthmic spondylolisthesis may be related to multiple factors rather than a single factor. Age, PI, PJA and P-F angle are potentially associated with spondylolisthesis.

Validation of a preoperative formula to estimate postoperative pelvic sagittal alignment and mobility before performing total hip arthroplasty for patients with hip osteoarthritis

BACKGROUND

Although it is important to consider pelvic alignment and mobility in the standing and sitting positions before THA, it is not known how to preoperatively predict individual postoperative pelvic alignment and mobility. The purpose of this study was to investigate the pelvic alignment and mobility before and after THA, and to develop a predictive formula using preoperative factors to calculate postoperative sagittal alignment and mobility.

METHODS

One hundred seventy patients were assessed. The 170 patients were randomly divided into a prediction model analysis group (n = 85) and an external validation group (n = 85). In the prediction model analysis group, preoperative spinopelvic parameters were used to develop the predictive formulas to predict the postoperative sacral slope (SS) in standing and sitting positions and ΔSS. These were applied to the external validation group and assessed.

RESULTS

R² in multiple linear regression models for postoperative SS in standing, SS in sitting and ΔSS were 0.810, 0.672, and 0.423, respectively. The values of predicted and postoperative parameters were very close with no significant difference: SS in standing (33.87 vs. 34.23, P = 0.834), SS in sitting (18.86 vs. 19.51, P = 0.228), and ΔSS (15.38 vs. 14.72, P = 0.619).

CONCLUSION

The present study showed that the pelvic alignment and mobility after THA can be predicted using preoperative factors. Although a model with higher accuracy is needed, it is important to use a predictive formula to estimate the postoperative condition before performing THA.

A Comprehensive Analysis of the Behavior of Pelvic Incidence After Different Posterior Spinal Procedures in Elderly Patients With Spinal Deformity

STUDY DESIGN

A retrospective case-control study.

OBJECTIVE

To evaluate the behavior of pelvic incidence (PI) after different posterior spinal procedures in elderly patients with adult spinal deformity (ASD), to determine the potential associated factors with the variability in PI after spinal surgery and to comprehensively analyze its mechanisms.

METHODS

Elderly patients underwent long fusion to sacrum with and without pelvic fixation were assigned to Group L+P and Group L-P, respectively. In Group L-P, those with severe sagittal deformity were selected as Group A. 20 elderly patients with severe sagittal deformity underwent short lumbar fusion were included as Group B. The following radiographic parameters were evaluated: thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), PI-LL, sagittal vertical axis (SVA), T1 pelvic angle (TPA), and pelvic parameters. PI changing more than 5° (△PI > 5°) was considered as substantially changed.

RESULTS

For the whole cohort and in Group L+P, PI were not substantially changed (△PI ≤ 5°) after surgery. Besides the severer sagittal malalignment in patients with △PI > 5° in Group L-P, relatively larger mean age, greater proportion of female and lower preoperative PI were found than those in patients with △PI ≤ 5°. 70.8% of patients had substantial increase of PI in Group A, while only 10% of patients had in Group B (P < 0.001).

CONCLUSION

PI behaves differently under different conditions in elderly ASD patients. Besides severe sagittal deformity, aging, female and low preoperative PI are also the potential risk factors of PI increasing after long fusion to sacrum.

Sacroiliac joint degeneration in degenerative lumbar spondylolisthesis and related risk factors: a retrospective study

OBJECTIVE

This study was performed to evaluate the degree of radiological sacroiliac joint (SIJ) degeneration in patients with degenerative lumbar spondylolisthesis (DLS). The related risk factors for SIJ degeneration were also investigated.

METHODS

We retrospectively analyzed the lumbar and pelvic computed tomography (CT) scans of 303 patients with DLS admitted from January 2018 to December 2021. One hundred and fifty-six age-, gender-, and body mass index-matched patients without lumbar anomality who underwent lower abdominal or pelvic computed tomography scans were included in the control group. Sagittal parameters were measured on full-length lateral radiographs. Two protocols (Backlund's grade and Eno's classification) were used to assess SIJ degeneration. Univariate analysis and bivariate and multivariate regression analysis were performed to identify the factors affecting SIJ degeneration in patients with DLS.

RESULTS

According to Backlund's grade and Eno's classification, SIJ degeneration was more severe in the DLS group than in the control group (P < 0.001). Multi-segment degenerative changes (P = 0.032), two-level DLS (P = 0.033), a history of hysterectomy (P < 0.001), lower extremity pain (P = 0.016), and pelvic pain (P = 0.013) were associated with more significant SIJ degeneration as assessed by Backlund's grade. The results of Pearson's correlation analysis showed positive correlation between the sagittal vertical axis and SIJ degeneration (r = 0.232, P = 0.009). The multivariate linear regression analysis showed that a history of hysterectomy was significantly correlated with SIJ degeneration in patients with DLS (r = 1.951, P = 0.008).

CONCLUSIONS

SIJ degeneration was more severe in patients with than without DLS. We should take SIJ degeneration into consideration when diagnosing and treating DLS especially those who had undergone previous hysterectomy or showed sagittal malalignment.

Association of age and spinopelvic function in patients receiving a total hip arthroplasty

Restricted spinopelvic mobility received attention as a contributing factor for total hip arthroplasty (THA) instability. However, it is still unknown, how the spinopelvic function is influenced by age. In identifying the patients at highest risk for altered spinopelvic mechanics the study aimed to determine the association of age on the individual segments of the spinopelvic complex and global spinal sagittal alignment in patients undergoing THA. 197 patients were included in the prospective observational study conducting biplanar stereoradiography (EOS) in standing and sitting position pre-and postoperatively. Two independent investigators assessed C7-sagittal vertical axis (C7-SVA), cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), anterior plane pelvic tilt (APPT), and pelvic femoral angle (PFA). Key segments of the spinopelvic complex are defined as lumbar flexibility (∆ LL = LL_standing - LL_sitting), pelvic mobility (∆ SS = SS_standing - SS_sitting) and hip motion (∆ PFA = PFA_standing - PFA_sitting). Pelvic mobility was further defined based on ∆ SS = SS_standing - SS_sitting as stiff (∆ SS < 10°), normal (∆ SS ≥ 10°-30°) and hypermobile (∆ SS > 30°). The patient collective was classified into three groups: (1) < 60 years (n = 56), (2) ≥ 60-79 years (n = 112) and (3) ≥ 80 years (n = 29). Lumbar flexibility (∆ LL) was decreased with increasing age between all groups (36.1° vs. 23.1° vs. 17.2°/p₁₊₂ < 0.000, p₂₊₃ = 0.020, p₁₊₃ < 0.000) postoperatively. Pelvic mobility (∆ SS) was decreased in the groups 2 and 3 compared to group 1 (21.0° and 17.9° vs. 27.8°/p₁₊₂ < 0.000, p₂₊₃ = 0.371, p₁₊₃ = 0.001). Pelvic retroversion in standing position (APPT) was higher in group 2 and 3 compared to group 1 (1.9° and - 0.5° vs 6.9°/p₁₊₂ < 0.000, p₂₊₃ = 0.330, p₁₊₃ < 0.000). Global sagittal spinal balance (C7-SVA) showed more imbalance in groups 2 and 3 compared to group 1 (60.4 mm and 71.2 mm vs. 34.5 mm/p₁₊₂ < 0.000, p₂₊₃ = 0.376, p₁₊₃ < 0.000) postoperatively. The preoperative proportion of patients with stiff pelvic mobility in group 1 was distinctly lower than in group 3 (23.2% vs. 35.7%) and declined in group 1 to 1.8% compared to 20.7% in group 3 after THA. Changes after THA were reported for groups 1 and 2 representing spinopelvic complex key parameter lumbar flexibility (∆ LL), pelvic mobility (∆ SS) and hip motion (∆ PFA), but not for group 3. This is the first study to present age-adjusted normative values for spinopelvic mobility. The subgroups with increased age were identified as risk cohort for altered spinopelvic mechanics and enhanced sagittal spinal imbalance and limited capacity for improvement of mobility after THA. This valuable information serves to focus in the preoperative screening on the THA candidates with the highest risk for abnormal spinopelvic function.

Dynamic change of pelvic incidence after long fusion to pelvis with S2-alar-iliac screw: a 2-year follow-up study

INTRODUCTION

Pelvic incidence (PI) is a key morphological parameter that reflects the relation between the sacrum and iliac wings. It is well accepted that PI remains constant after reaching maturity. However, recent studies indicated that PI might be altered after lumbosacral fusion. Additionally, it remains uncertain on the long-term influence of long fusion to pelvis with S2-alar-iliac screw on PI in patients with adult spinal deformity (ASD).

STUDY DESIGN

A retrospective study.

OBJECTIVE

To investigate whether and how PI would change during the follow-up in ASD patients who underwent S2AI fixation and to identify factors associated with the change in PI.

METHODS

We retrospectively reviewed all ASD patients who underwent spinal surgery using S2AI screws between November 2014 and January 2017 at our institution. Patients with minimum follow-up of two years were included. The following sagittal radiographic parameters were measured: PI, Lumbar lordosis (LL), pelvic tilt (PT), PI-LL, sagittal vertical axis (SVA) at pre-op, post-op and 2-year follow-up. According to the changes in PI at immediate post-operation, patients were classified into two groups; Group A: Changes of PI less than or equal 5° and Group B: Changes of PI greater than 5°.

RESULTS

A total of 82 ASD patients (Group A: 32, Group B: 50; mean age of 53.5 ± 12.6 years) with a mean follow-up period of 30.2 ± 9.2 months were included in this study. At immediate post-operation, Group A showed no significant change in PI (45.7° ± 11.4° to 45.3° ± 11.2°, p = 0.749); while Group B had a significant decrease in PI (51.6° ± 14.5° to 40.9° ± 14.0°, p < 0.001). At the last follow-up, 48% patients (24/50) in Group B had a significant increase in PI (32.8° ± 6.4° to 45.8° ± 11.2°, p < 0.001). Intergroup analysis showed that ΔPI, post-op PI, post-op PT and age were significantly different between both groups. In addition, pre-op PI, post-op PI, post-op PT, post-op PI-LL were significantly correlated with ΔPI at last follow-up. Also, logistic regression analysis showed that post-op PI was the associated risk factor (OR = 0.865, p = 0.024) for PI-LL mismatch.

CONCLUSION

Our study showed that PI decreased in more than half of ASD patients immediately after spinal surgery using S2AI screws. Approximately 48% of them were able to recover during the 2-year follow-up. Lower pre-op PI, post-op PI and PT were found to be strongly associated with the return of PI. Thus, these current findings indicated that patients with a high PI at pre-operation should not be over-corrected to avoid PI-LL mismatch postoperatively.

The Utility of a Novel Proximal Femur Maturity Index for Staging Skeletal Growth in Patients with Idiopathic Scoliosis

BACKGROUND

For growing patients, it is ideal to have a growth plate visible in routine radiographs for skeletal maturity assessment without additional radiation. The proximal femoral epiphyseal ossification is in proximity to the spine; however, whether it can be used for assessing a patient's growth status remains unknown.

METHODS

Two hundred and twenty sets of radiographs of the spine and the left hand and wrist of patients with idiopathic scoliosis were assessed for skeletal maturity and reliability testing. Risser staging, Sanders staging (SS), distal radius and ulna (DRU) classification, the proximal humeral ossification system (PHOS), and the novel proximal femur maturity index (PFMI) were used. The PFMI was newly developed on the basis of the radiographic appearances of the femoral head, greater trochanter, and triradiate cartilage. It consists of 7 grades (0 to 6) associated with increasing skeletal maturity. The PFMI was evaluated through its relationship with pubertal growth (i.e., the rate of changes of standing and sitting body height [BH] and arm span [AS]) and with established skeletal maturity indices. Longitudinal growth data and 780 corresponding spine radiographs were assessed to detect peak growth using receiver operating characteristic (ROC) curve analysis.

RESULTS

The PFMI was found to be correlated with chronological age (τ b = 0.522), growth rates based on standing BH (τ b = -0.303), and AS (τ b = -0.266) (p < 0.001 for all). The largest growth rate occurred at PFMI grade 3, with mean standing BH growth rates (and standard deviations) of 0.79 ± 0.44 cm/month for girls and 1.06 ± 0.67 cm/mo for boys. Growth rates of 0.12 ± 0.23 cm/mo (girls) and 0 ± 0 cm/mo (boys) occurred at PFMI grade 6, indicating growth cessation. Strong correlations were found between PFMI gradings and Risser staging (τ b = 0.743 and 0.774 for girls and boys), Sanders staging (τ b = 0.722 and 0.736, respectively), and radius (τ b = 0.792 and 0.820) and ulnar gradings (τ b = 0.777 and 0.821), and moderate correlations were found with PHOS stages (τ b = 0.613 and 0.675) (p < 0.001 for all). PFMI gradings corresponded to as young as SS1, R4, U1, and PHOS stage 1. Fair to excellent interrater and intrarater reliabilities were observed. PFMI grade 3 was most prevalent and predictive for peak growth based on ROC results.

CONCLUSIONS

The PFMI demonstrated clear pubertal growth phases with satisfactory reliability. Grade 3 indicates peak growth and grade 6 indicates growth cessation.

CLINICAL RELEVANCE

The use of PFMI can benefit patients by avoiding additional radiation in skeletal maturity assessment and can impact current clinical protocol of patient visits. PFMI gradings had strong correlations with SS, DRU gradings, and Risser staging, and they cross-referenced to their established grades at peak growth and growth cessation. PFMI may aid in clinical decision making.

Sacral anatomical parameters varies in different Roussouly sagittal shapes as well as their relations to lumbopelvic parameters

PURPOSE

To study the normal variations in sacral anatomical parameters in different Roussouly sagittal shapes and the association between sacral anatomical parameters and lumbopelvic parameters in healthy adults.

METHODS

A cohort of 239 healthy volunteers between 18 and 45 years old was enrolled in this study. A full-spine, standing X-ray was taken for each volunteer. The following parameters were measured: the sacral table angle (STA), sacral kyphosis (SK), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), and lumbar lordosis apex (LLA). Two hundred and thirty-nine volunteers were classified into five groups according to the Roussouly classification. The differences in sagittal parameters among the five groups were evaluated by one-way analysis of variance. The correlations between lumbopelvic parameters and sacral anatomical parameters were analyzed, and simple linear regressions were simultaneously constructed.

RESULT

The sacral anatomical parameters vary in different Roussouly sagittal shapes. Correlation analysis revealed that the significant correlations between sacral anatomical parameters and lumbopelvic parameters. The STA correlated with PI (r = -.690, P <.001), PT (r = -.216, P = .001), SS (r = -.631, P <.001), LL (r = -.491, P <.001), and LLA (r = 0.515, P <.001). The corresponding regression formulae were as follows: PI = -0.991*STA + 143(R 2 = .476), LL = 0.870*STA-135.1(R 2 = .242), and LLA = 0.039*STA -0.087(R 2 = .265). The SK correlated with PI (r = .471, P <.001), PT (r = .445, P = .001), SS (r = .533, P <.001), LL (r = .438, P <.001), and the LLA (r = -.265, P <.001). The corresponding regression formulae were as follows: PI = 0.38*SK + 27.22(R 2 = .396), LL = -0.35*SK - 35.99(R 2 = .192), and LLA = -0.01*SK + 4.25(R 2 = .201).

CONCLUSIONS

The sacral anatomical parameters vary in different Roussouly sagittal shapes and have strong correlations with lumbopelvic parameters, which demonstrates that the specific lumbar shape can be affected by the sacral morphology. Moreover, the predictive models of lumbopelvic parameters based on SK and STA have been provided, which demonstrates constant sacral anatomical parameters could serve as good supplementary index of PI to predict ideal lumbar parameters.

Global Sagittal Balance of Spine in Asymptomatic Controls: A Systematic Review and Meta-Analysis

OBJECTIVE

To assess the global sagittal balance of spine (GSBS) in asymptomatic controls.

METHODS

PubMed, Scopus, Cochrane library, and Web of Science searched up to July 2020. Studies were screened for the GSB parameters including T1 pelvic angle (TPA), spinosacral angle (SSA), sagittal vertical axis (SVA), C7/sacrofemoral distance ratio (Barrey index), odontoid hip axis (OD-HA), and Full Balance Index (FBI) as measured in asymptomatic participants. A meta-analysis was performed to synthesize pooled estimates. Heterogeneity and publication bias were assessed.

RESULTS

Overall, 76 studies were identified including 12,169 participants (54.7% female) with mean age ranges from 12.0 to 72.9 years old. We used the Newcastle-Ottawa Scale (NOS) to evaluate the quality of studies included in this review. Begg's test did not indicate obvious publication bias. The pooled analysis reveals that the mean (standard deviation) normative values were: 1) age ˃18 years, SSA (°), 127.6 (0.89); SVA absolute value (millimeters), 13.1 (1.13); TPA (°), 9.8 (1.13); T1SPI (°), -4.3 (0.57); and Barrey index absolute value, 0.51 (0.3). The mean value of the OD-HA (°) was reported 2.9 (1.6), and the FBI average value was less than 5°. 2) Age ≤18 years, SSA (°), 132.1 (8.3); SVA absolute value (millimeters), 11.9 (2.0); and Barrey index, -0.7 (8.3). A significant difference was observed between the 2 age groups based on SVA and SSA.

CONCLUSIONS

This paper presents normative data on TPA, SSA, SVA, Barrey index, OD-HA, and FBI as a reference for evaluating/measuring a GSB of spine in asymptomatic controls.

Second sacral sacralalar-iliac (S2AI) screw placement in adult degenerative scoliosis (ADS) patients: an imaging study

Background

The imaging characteristics of sacral sacralalar-iliac (S2AI) screw trajectory in adult degenerative scoliosis (ADS) patients will be determined.

Methods

S2AI screw trajectories were mapped on three-dimensional computed tomography (3DCT) reconstructions of 40 ADS patients. The starting point, placement plane, screw template, and a circle centered at the lowest point of the ilium inner cortex were set on these images. A tangent line from the starting point to the outer diameter of the circle was selected as the axis of the screw trajectory. The related parameters in different populations were analyzed and compared.

Results

The trajectory length of S2AI screws in ADS patients was 12.00 ± 0.99 cm, the lateral angle was 41.24 ± 3.92°, the caudal angle was 27.73 ± 6.45°, the distance from the axis of the screw trajectory to the iliosciatic notch was 1.05 ± 0.81 cm, the distance from the axis of the screw trajectory to the upper edge of the acetabulum was 1.85 ± 0.33 cm, and the iliac width was 2.12 ± 1.65 cm. Compared with females, the lateral angle of male ADS patients was decreased, but the trajectory length was increased (P < 0.05). Compared to patients without ADS in previous studies, the lateral angle of male patients was larger, the lateral angle of female patients was increased, and the caudal angle was decreased (P < 0.05).

Conclusions

There is an ideal trajectory of S2AI screws in ADS patients. A different direction should be noticed in the placement of S2AI screws, especially in female patients.

Risk factors for acute proximal junctional kyphosis after adult spinal deformity surgery in preoperative motion analysis

OBJECTIVE

This study aimed to examine which motion analysis parameters regarding the dynamic aspects and/or balance affect the development acute proximal junctional kyphosis (PJK) following adult spinal deformity (ASD) surgery.

METHODS

A total of 90 consecutive patients were recruited prospectively, who underwent a corrective surgery for ASD with sagittal imbalance. According to the development of acute PJK within 6 months after surgery, the patients were divided into the PJK+ and PJK- groups. Before surgery, three-dimensional gait analyses were performed using a motion analysis system. The preoperative continuous and categorical variables were compared between the PJK+ and PJK- groups using independent t tests and chi-square tests, respectively. Finally, a multivariate logistic regression model was used to identify the risk factors and calculate the odds ratio (OR) for acute PJK.

RESULTS

A total of 20 and 70 patients were classified into the PJK+ and PJK- groups, respectively. There were no differences in the spinopelvic radiologic parameters pre- and postoperatively between the PJK+ and PJK- groups. The PJK+ group showed a significantly higher mean anterior pelvic tilt (Ant-PT) angle in preoperative motion analysis than the PJK- group (P = 0.001 for both sides). Multivariate analysis identified the mean Ant-PT angle (P = 0.047; OR 1.127; 95% CI 1.002-1.267) as a significant risk factor for acute PJK.

CONCLUSION

Preoperative Ant-PT angle during walking was associated with a higher OR in acute PJK after surgery.

Global sagittal alignment after surgery of right thoracic idiopathic scoliosis in adolescents and adults with and without thoracic hypokyphosis

This study aimed to characterize global sagittal alignment in adolescent idiopathic scoliosis (AIS) with normal kyphosis (NTK, kyphosis > 10°) and with thoracic hypokyphosis (THK, kyphosis < 10°), before and after posterior spinal fusion, and compare them with asymptomatic controls. 27 AIS girls and young adults with right thoracic curves were included (seventeen with age ≤ 18 years, then age > 21). Biplanar radiographies were acquired at baseline, immediate post-operatively, 1-year and 2-year follow-up, and 3D reconstruction of the spine and pelvis was performed. NTK and THK showed different global sagittal alignment, as well as differences compared to controls. AIS with THK at baseline had higher SVA/SFD (2.0 ± 2.9 vs - 0.4 ± 1.9; P < 0.05) and OD-HA (0.2 ± 1.4° vs - 1.3 ± 1.6°; P < 0.05) than controls, indicating that THK had compensated balance with unusual forward leaning posture. Immediately post-operation, SVA/SFD remained high (1.3 ± 3.0) while OD-HA reversed (- 1.2 ± 1.7°), indicating that THK patients had found partially compensated balance. After 2-yeas, both SVA/SFD (- 1.3 ± 2.1) and OD-HA (- 1.4 ± 0.9°) were normalized. The changes in global sagittal alignment and mechanism of balance are different in AIS with or without THK. As the head plays a critical role on balance during immediate and delayed post-operation, OD-HA can be complementary parameter for assessing global balance during post-operative follow-up of AIS patients with THK.

Movement of the sacroiliac joint: Anatomy, systematic review, and biomechanical considerations

Several researchers investigated the anatomy and biomechanics of the sacroiliac joint (SIJ) to understand the relationship between lower back pain and the SIJ. Many studies concluded that the SIJ has little movement; however, some studies using spinopelvic parameters mentioned high change in pelvic incidence (PI). In this study, SIJ movement and PI change reported in previous studies were reviewed according to position and posture changes. Literature on SIJ movement was reviewed by searching through the publication databases. In biomechanical studies, the result of the rotational angle in the sagittal plane was mainly investigated to compare with the results of PI change. From the results of SIJ movement studies, the minimum movement of nutation and count-nutation was 0.01°, and maximum movement was 2.27°. From the results of PI change studies with different positions and movements, the highest change was 9°, and the lowest change was 0°. Movement of the SIJ was limited by its anatomical structure; maximum movement of the SIJ was 9° in a previous study. Therefore, SIJ movement should be studied more intensely as biomechanical perspective to understand its movement.

Can pelvic incidence change after spinal deformity correction to the pelvis with S2-alar-iliac screws?

PURPOSE

Pelvic incidence (PI) is assumed to be fixed, yet studies have reported PI changes after long fusions to the pelvis. In a cohort of ASD patients undergoing surgery with S2-alar-iliac (S2AI) screws, we sought to: (1) report the magnitude of PI changes, and (2) evaluate subsequent pelvic parameter changes.

METHODS

A retrospective case series of ASD patients undergoing surgical correction with S2AI screw placement and sagittal cantilever correction maneuvers was conducted. Patients were categorized based on preoperative PI: High-PI (H-PI) (PI ≥ 60°); Normal-PI (N-PI) (60° > PI > 40°); Low-PI (L-PI) (PI ≤ 40°). PI was measured preoperatively and immediately postoperatively. A significant PI change was established a priori at ≥ 6.0. PI, pelvic tilt (PT), lumbar lordosis (LL), and PI-LL mismatch were analyzed.

RESULTS

In 68 patients (82.3% female, ages 22-75 years), the average change in PI was 4.6° ± 3.1, and 25 (36.8%) had a PI change ≥ 6.0° with breakdown as follows: H-PI 12 (66.7%) patients, 9 (25.87%) patients, and 4 (33.3%) patients. Of 25 patients with PI changes, 10 (14.7%) had a PI increase and 15 (22.1%) had a PI decrease. Significant improvements were seen in PT, LL, PI-LL mismatch in all patients with a PI change ≥ 6.0°, in addition to both subgroups with an increase or decrease in PI.

CONCLUSIONS

PI changes of ≥ 6.0° occurred in 36.8% of patients, and H-PI patients most commonly experienced PI changes. Despite PI alterations, pelvic parameters significantly improved postoperatively. These results may be explained by sacroiliac joint laxity, S2AI screw placement, or aggressive sagittal cantilever techniques.

Cervical Sagittal Alignment: Literature Review and Future Directions

Cervical alignment as a concept has come to the forefront for spine deformity research in the last decade. Studies on cervical sagittal alignment started from normative data, and expanded into correlation with global sagittal balance, prognosis of various conditions, outcomes of surgery, definition and classification of cervical deformity, and prediction of targets for ideal cervical reconstruction. Despite the recent robust research efforts, the definition of normal cervical sagittal alignment and cervical spine deformity continues to elude us. Further, many studies continue to view cervical alignment as a continuation of thoracolumbar deformity and do not take into account biomechanical features unique to the cervical spine that may influence cervical alignment, such as the importance of musculature connecting cranium-cervical-thoracic spine and upper extremities. In this article, we aim to summarize the relevant literature on cervical sagittal alignment, discuss key results, and list potential future direction for research using the '5W1H' framework; "WHO" are related?, "WHY" important?, "WHAT" to evaluate and "WHAT" is normal?, "HOW" to evaluate?, "WHEN" to apply sagittal balance?, and "WHERE" to go in the future?

Impact of spinal alignment and stiffness on impingement after total hip arthroplasty: a radiographic study of pre- and post-operative spinopelvic alignment

PURPOSE

Recent studies have revealed the impact of spinopelvic factors on the risk of dislocation after total hip arthroplasty (THA). This study examined the risk factors of impingement that can lead to dislocation using pre- and postoperative spinopelvic radiographs.

METHODS

We studied 143 consecutive patients with end-stage hip osteoarthritis who were eligible for THA at our institute. Pre-operative pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), sagittal vertical axis (SVA) in the standing and sitting position, and centre-edge angle (CE) were measured. The post-operative SS, LL, SVA, femoral shaft angle, and radiographic alignment of the acetabular component were also measured. We performed a multiple linear regression analysis to determine the risk factors for anterior and posterior impingement using pre-operative demographic and radiographic parameters. The clearance of anterior and posterior implant impingement was used for the surrogate-dependent variable for dislocation.

RESULTS

A total of 95 patients were included in the analysis. There were significant differences in SS, LL, and SVA between the standing and sitting positions (P < 0.001). A multiple linear regression analysis showed that the PI-LL, LL changes, and CE were associated with the posterior impingement (β = - 0.21, 0.24, and -0.27, respectively). Moreover, PI-LL was also associated with the anterior impingement in the sitting position (β = - 0.27).

CONCLUSION

Our results suggest that a flatback with a rigid spine leads to posterior impingement, and a well-balanced spine leads to anterior impingement, which can be a potential risk factor for dislocation.

Comparison of sacroiliac joint degeneration between patients with sagittal imbalance and lumbar spinal stenosis

PURPOSE

The purpose of this study was to compare the degeneration of sacroiliac joints (SIJs) between adult spinal deformity (ASD) patients with sagittal imbalance and an age- and sex-matched lumbar spinal stenosis (LSS) patients without sagittal imbalance.

MATERIALS AND METHODS

The age- and sex-matched case-control study consists of two groups: the ASD group and the other group consisting of patients with LSS (LSS group). The study population consisted of 98 patients in each group. The spinopelvic parameters such as pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis, and sagittal vertical axis (SVA) were measured. To evaluate degeneration of SIJ, two protocols (Backlund's grade and Eno's classification) were used.

RESULT

SIJ degeneration in the ASD group was more severe than that in the LSS group, as assessed by both Backlund's grade and Eno's classification (P < 0.001 for both). Age correlated significantly with PI in both the ASD and LSS groups (r = 0.285; P = 0.005, r = 0.218; P = 0.031, respectively). The total Backlund's grading score and the SVA were significantly correlated with PI in the ASD group (r = 0.344; P < 0.001, r = 0.276; P = 0.007, respectively), but not in the LSS group (r = 0.156; P = 0.126, r = 0.189; P = 0.067, respectively).

CONCLUSIONS

ASD patients with sagittal imbalance demonstrated more severe SIJ degeneration compared to the age- and sex-matched LSS group. PI was significantly correlated with both SIJ degeneration and SVA only in the ASD group.

Pelvic mobility before and after total hip arthroplasty

BACKGROUND

Pre-operative evaluation of pelvic motion using the sacral slope (SS) has been proposed for risk assessment of dislocation after total hip arthroplasty (THA). The purposes of this study were to elucidate the statistical characteristics of pre-operative and post-operative pelvic mobility and investigate the relationship between pre-operative spinopelvic factors and post-operative pelvic mobility.

METHODS

Eighty-six patients with osteoarthritis were assessed. The parameters evaluated were lumbar lordosis angle and the SS in the standing and sitting preo-peratively and post-operatively. The pelvic mobility was defined as the difference in the SS between standing and sitting. The presence of osteoarthritis in the contralateral hip, spondylolisthesis, vertebral compression fracture and lumbar scoliosis was investigated.

RESULTS

The median (interquartile range) pre-operative and post-operative pelvic mobility was 19.0 (13.75-27.0) and 16.0 (10.0-25.25), respectively, with significant difference. The pre-operative SS while standing and pre-operative pelvic mobility were associated with post-operative pelvic mobility (r = 0.409, P < 0.05 and r = 0.533, P < 0.05). The multivariate linear regression analysis showed that the following factors contributed to post-operative pelvic mobility: incidence of osteoarthritis in the contralateral hip, lumbar scoliosis, pre-operative SS while standing and pre-operative SS while sitting.

CONCLUSION

The pre-operative and post-operative pelvic mobility is not equal and ranges widely among patients. In addition to assessment of pre-operative pelvic mobility, other pre-operative spinopelvic factors may also influence post-operative pelvic mobility, such as the SS while standing and sitting, the condition of the contralateral hip and the presence of scoliosis. Risk assessment for dislocation using these pre-operative factors may be useful before THA.

The Effects of Pelvic Incidence in the Functional Anatomy of the Hip Joint

BACKGROUND

The spine-pelvis-hip interaction during postural change should be considered in the functional anatomy of the hip. The component parts of this anatomy and how they influence hip function are important to know. Pelvic incidence (PI) is one of these components. We studied if PI was preoperatively predictive of impingement risk and if it postoperatively influences hip position, which could cause outliers from the functional safe zone of hip replacement.

METHODS

This was a prospective radiographic study of 187 consecutive patients (200 hips) who had lateral spinopelvis-hip radiographs before and after primary total hip arthroplasty with measurements of the component factors that influence mobility and position of the functional anatomy. The predictive value of PI for risk of impingement of the hip and its postoperative relationship to functional safe-zone outliers were assessed. Forty-one dislocations from our clinical practice were also reviewed.

RESULTS

Of 200 hips, the PI was normal in 145 hips (73%), low in 18 hips (9%), and high in 37 hips (19%). Eighty-two hips had spinopelvic imbalance: 12 (67%) of the 18 hips with low PI, 56 (39%) of the 145 hips with normal PI, and 14 (38%) of the 37 hips with high PI. Low-PI hips was the most predictive of the risk of impingement and postoperatively these hips had the most outliers from the functional safe zone.

CONCLUSIONS

PI is an anatomical component that is predictive of both impingement risk and functional safe-zone outliers. Preoperative risk, based on factors such as the Lewinnek zones and combined anteversion, is an established guide in determining cup position in hip replacement. Low-PI hips that have the "terrible triad" of a posteriorly tilted pelvis, stiff pelvic mobility, and increased femoral flexion therefore have no functional safe zone.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Do Clinical Outcomes and Sagittal Parameters Differ Between Diabetics and Nondiabetics for Degenerative Spondylolisthesis Undergoing Lumbar Fusion?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To assess the effect of diabetes mellitus (DM) on clinical and radiographic outcomes in patient with degenerative spondylolisthesis undergoing posterior lumbar spinal fusion.

METHODS

Analysis of patients who underwent open posterior lumbar spinal fusion from 2011 to 2018. Patients being medically treated for DM were identified and separated from nondiabetic patients. Visual analogue scale Back/Leg pain and Oswestry Disability Index (ODI) were collected, and achievement of minimal clinically important difference was evaluated. Lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and PI-LL difference were measured on radiographs. Rates of postoperative complications were also collected.

RESULTS

A total of 850 patients were included; 78 (9.20%) diabetic patients and 772 (90.80%) nondiabetic patients. Final PI-LL difference was significantly larger (P = .032) for patients with diabetes compared to no diabetes, but there were no other significant differences between radiographic measurements, operative time, or postoperative length of stay. There were no differences in clinical outcomes between the 2 groups. Diabetic patients were found to have a higher rate of discharge to a facility following surgery (P = .018). No differences were observed in reoperation or postoperative complication.

CONCLUSIONS

While diabetic patients had more associated comorbidities compared with nondiabetic patients, they had similar patient-reported and radiographic outcomes. Similarly, there are no differences in rates of reoperation or postoperative complications. This study indicates that diabetic patients who have undergone thorough preoperative screening of related comorbidities and appropriate selection should be considered for lumbar spinal fusion.

Does increasing age impact clinical and radiographic outcomes following lumbar spinal fusion?

BACKGROUND CONTEXT

Despite the growing senior population within the United States, there is a lack of consensus regarding the safety and efficacy of performing lumbar spinal fusion for this population.

PURPOSE

To evaluate the clinical and radiographic outcomes in different age cohorts following lumbar spinal fusion.

STUDY DESIGN

Retrospective cohort analysis.

PATIENT SAMPLE

Analysis of 1,184 patients who underwent posterolateral lumbar fusion from 2011 to 2018. Surgery was indicated after failure of conservative treatment to address radiculopathy and/or neurogenic claudication. Patients were excluded if they were under 18 years of age at the time of surgery, had a lumbar fracture, tumor, or infection, or had fusions involving the thoracic spine, high-grade spondylolisthesis, or concomitant deformity. Of the 1,184 patients, 850 patients were included. Patients were divided into three roughly equal groups for analysis: young (18-54 years), middle-aged (55-69 years), and senior (≥70 years).

OUTCOME MEASURES

Visual Analog Scale Back/Leg pain, and Oswestry Disability Index (ODI) were collected, and achievement of minimal clinically important difference was evaluated. Lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), and PI-LL difference were measured on radiographs. Rates of postoperative complications were analyzed.

METHODS

Several radiographic parameters were measured using plain radiographs obtained at preoperative, immediately postoperative (standing radiographs performed on postoperative day 1), and most recent follow-up visits. Preoperative and final patient-reported outcomes, along with demographic information, were obtained all patients. Binary outcome variables were compared between groups with multivariate logistic regression, and continuous outcome variables were compared using multivariate linear regression, with age 18 to 54 years used as the reference. Multivariate regressions were used to compare outcomes between cohorts while controlling baseline characteristics.

RESULTS

A total of 850 patients were included; 330 young (38.80%), 317 middle-aged (37.30%), and 203 senior (23.90%). Seniors had higher postoperative length of stay compared to younger patients (p<.001). Younger patients had worse final ODI scores compared to middle-aged patients (p=.002). Seniors had higher rates of proximal ASD (p=.002) compared to young patients. There was no difference in achievement of minimal clinically important differences (MCID) between all three groups.

CONCLUSIONS

Senior patients have significant improvement in patient-reported clinical outcomes, despite having greater comorbidities, and longer length of stay. However, given a general lack of achievement of MCID across all cohorts, these findings suggest the need for a critical re-evaluation of the role of lumbar spinal fusion in the management of patients with refractory radiculopathic and/or neurogenic claudication symptoms.

Percutaneous kyphoplasty for osteoporotic vertebral compression fractures improves spino-pelvic alignment and global sagittal balance maximally in the thoracolumbar region

Background

Osteoporotic vertebral compression fractures (OVCFs) often cause local kyphosis. Percutaneous kyphoplasty (PKP) is a common method for the treatment of local kyphosis. However, the influence of kyphoplasty on spino-pelvic alignment and global sagittal balance when performed at specific treatment sites in the spine remains unclear.

The purpose of the study is to investigate the influence of different fracture sites and PKP treatment on the spino-pelvic alignment and global sagittal balance in patients with OVCFs.

Methods

90 patients with OVCF who underwent PKP were included in the retrospective study. According to the site of the fractured vertebrae, all the cases were divided into 3 groups: Main thoracic (MT) group (T1 to T9), Thoracolumbar (TL) group (T10 to L2) and Lumbar (LU) group (L3 to L5). 26 healthy elderly volunteers (aged over 59) were enrolled as the control group. Sagittal spino-pelvic parameters were measured on the full-spine radiographs preoperatively and postoperatively. Information of sagittal spino-pelvic parameters and global sagittal balance was gathered.

Results

Compared with the Control group, TL group showed significant differences in almost all parameters, except pelvic incidence (PI) and lumbar lordosis (LL). While only local sagittal parameters (Thoracic kyphosis (TK), Thoracolumbar kyphosis (TLK), LL) were significantly different in MT group. There was no significant difference in almost all of the parameters except for PT and TPA in LU group.

Correspondingly, the sagittal parameters of TL group improved best after PKP, except for thoracic kyphosis (TK) and sagittal vertical axis (SVA). In MT group, only TLK was significantly decreased, while in LU group, only local kyphosis Cobb angle and SSA were improved.

Conclusions

OVCF mainly occurs in the thoracolumbar region. Compared with MT group and LU group, OVCF occurred in the thoracolumbar region had greater influence on the spino-pelvic alignment and global sagittal balance. When PKP was performed, the improvement of sagittal balance parameters of TL group was the best in the three groups.

Risk factors of degenerative lumbar scoliosis in patients with lumbar spinal canal stenosis

Lumbar spinal canal stenosis (LSCS) associated with degenerative scoliosis has being increasingly aware by the public and studied by many researchers. Degenerative changes leading to spinal stenosis can precede a spinal deformity which will develop into the de novo scoliosis. There are few studies focusing on the risk factors contributing to the degenerative lumbar scoliosis (DLS) in lumbar spinal stenosis patients.From September, 2017 to December, 2017, 181 patients who were diagnosed with LSCS in the outpatient department of our hospital were enrolled in this retrospective investigation. The patients were divided into 2 groups: DLS group (Cobb angle >10°) and LSCS group. Sex, age, smoking status (yes or no), occupation (heavy or light labor), body mass index (BMI), bone mineral density (BMD) and radiographic parameters including the lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), thoracic kyphosis (TK), coronal vertical axis, and sagittal vertical axis (SVA) are all evaluated as potential risk factors. Multivariate logistic regression analysis and receiver-operating characteristic curves were used to identify potential risk factors.Forty-five of 181 patients were diagnosed with DLS and involved in the DLS group. There were significant differences between the 2 groups in BMI (P < .001), LL (P = .0046), BMD (P < .001), SVA (P < .001), and TK (P = .047). BMD < -1.85 g/cm (adjusted odds ratio [AOR] 0.030, 95% confidence interval [CI] 0.008-0.107, P < .001), BMI >25.57 kg/m (AOR 1.270, 95% CI 1.040-1.551, P = .019), and SVA >3.98 cm (AOR 3.651, 95% CI 2.226-5.990, P < .001) had good accuracy to predict the formation of degenerative lumbar scoliosis based on degenerative lumbar spinal stenosis.Degenerative lumbar scoliosis has a high incidence in degenerative lumbar spinal stenosis. BMD <-1.85 g/cm, BMI >25.57 kg/m, and SVA >3.98 cm were the potential risk factors for the formation of degenerative lumbar scoliosis based on degenerative lumbar spinal stenosis.

Failure of Pelvic Compensation in Patients With Severe Positive Sagittal Imbalance: Comparison Between Static Radiographs and Gait Analysis of Spinopelvic Parameters in Adult Spinal Deformity and Lumbar Stenosis

STUDY DESIGN

Case-control study for motion analysis.

OBJECTIVE

To compare spinopelvic parameters using static radiographs with the values obtained using motion analysis during gait between adult spinal deformity (ASD) or lumbar spinal stenosis (LSS).

SUMMARY OF BACKGROUND DATA

It is still unclear whether measurement of radiological parameters using static radiographs can reflect natural sagittal balance during gait in the patients with severe positive sagittal imbalance.

METHODS

In this age- and sex-matched case control study, a total of 40 patients, each 20 subjects with either ASD or LSS who were scheduled to undergo surgery were included. Both clinical outcomes and sagittal spinopelvic parameters, including sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), and pelvic incidence (PI) were measured. In motion analysis during walking, the angle of anterior pelvic tilt and the angles of the pelvis, hip, and knee were estimated. The correlation between variables was analyzed.

RESULTS

On standing lateral x-rays, SVA, PT, and PI - LL were significantly higher in the ASD group while SS and LL were significantly lower in the ASD group. However, on motion analysis, the average mean anterior pelvic tilt ± SD values in the ASD group were 8.3 ± 10.7 and 8.5 ± 10.7 on the right and left, respectively, and were not different from matched values in the LSS group. A Bland-Altman plot demonstrated a good agreement between the SS in the x-ray and anterior pelvic tilt in the motion analysis. In the ASD group, SS and SVA showed a significant positive correlation with mean anterior pelvic tilt in motion analysis during gait.

CONCLUSION

The present study showed that the failure of pelvic compensation would likely occur in patients with severe positive sagittal imbalance during walking.

LEVEL OF EVIDENCE

3.

Evaluation of anatomical pelvic parameters between normal, healthy men and women using three-dimensional computed tomography: a cross-sectional study of sex-specific and age-specific differences

Background

Sagittal spinal balance and standing posture are affected by pelvic morphology, especially pelvic incidence (PI). However, it is not difficult to identify the hip center because of overlap of the pelvis, image contrast, and soft tissue artifacts. Measurements of PI are not always suitable in all patients, especially those with osteoarthritis of the hip joint whose femoral head is nonspherical, subluxed, or dislocated. We measured PI, pelvic tilt (PT), and sacral slope (SS) as anatomical parameters using a novel three-dimensional measurement in order to compare the pelvic morphology between normal, healthy men and women.

Methods

In this cross-sectional study, we evaluated 108 Japanese subjects (55 men, 53 women) without low back or knee pain. We used the three-dimensional pelvis model adjusted to the anterior pelvic plane and measured the pelvic parameters. The subjects were stratified by age (< 50 versus ≥ 50 years) and sex. Intraobserver and interobserver reliabilities were calculated with intraclass correlation coefficients.

Results

There was no significant difference in PI, anatomical-PT, and anatomical-SS between sexes. There was a strong correlation between PI and anatomical-SS in men and women (R = 0.790 and 0.715, respectively). Values of anatomical-PT were lower, and values of anatomical-SS were greater among older subjects than among younger subjects; the value of PI was similar between younger and older subjects. Intraobserver and interobserver mean absolute differences were about 2 mm and 2°, respectively; the intraclass correlation coefficient was > 0.87.

Conclusions

We found a strong correlation between PI and anatomical-SS in men and women. This novel measurement concept may be useful to estimate PI from anatomical-SS because the measurements of PI are not always suitable in all patients, especially those with osteoarthritis of the hip joint whose femoral head is not spherical or whose femoral head is subluxed or dislocated. This is the first report to describe the relationship between PI, anatomical-PT, and anatomical-SS as morphologic parameters with a high interclass correlation coefficient for intraobserver and interobserver reliabilities.

Characteristics and correlation analysis of spino-pelvic sagittal parameters in elderly patients with lumbar degenerative disease

Background

Retrospective analysis of the characteristics and correlation of spino-pelvic sagittal parameters in elderly patients with lumbar degenerative disease.

Methods

Eighty-seven patients with lumbar degenerative disease, with an average age of 75.4 years old, were enrolled in the observation group. They were all from the orthopedics department of Beijing Hospital and got enrolled in this study from August 2015 to October 2017. Another 80 volunteers, with an average age of 74.5 years old, were enrolled in the control group. Standing lateral radiographs of the full-length spine were taken for all subjects. The following spino-pelvic sagittal parameters were measured: sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT). Statistical analysis was performed to compare the differences of the parameters between groups, and the correlation analysis was also performed.

Results

SVA, PI, and PT of the observation group were significantly higher than those of the control group (p < 0.01), while LL and SS were significantly lower in the observation group (p < 0.01). No significant differences were found in TK between the two groups. The correlation analyses showed that PI was significantly correlated with SS and PT in both the observation group (p < 0.01) and the control group (p < 0.01), so as the SVA-PI (p < 0.05) and SVA-PT (p < 0.01). SS-PT was also significantly correlated in the observation group (p < 0.01) and in the control group (p < 0.05). LL was significantly correlated with all the other parameters in the observation and control groups, including SVA (p < 0.01; p < 0.01), TK (p < 0.01; p < 0.01), PI (p < 0.01; p < 0.01), SS (p < 0.01; p < 0.01), and PT (p < 0.01; p < 0.01). SVA-SS (p < 0.05), TK-PI (p < 0.05), and TK-SS (p < 0.01) were significantly correlated in the control group but not in the observation group.

Conclusion

Reduced coordination of the spine and pelvis in elderly patients with lumbar degenerative disease was observed. Many of the cases were in the state of sagittal imbalance, with the trunk center of gravity moving forward, the integral sagittal alignment becoming straight, and the pelvic posterior tilt increasing. Pelvic parameters were significantly correlated with each other, which may affect the sagittal curve of the spine. LL was a core parameter that significantly correlated with various sagittal parameters.

Spinal Balance/Alignment - Clinical Relevance and Biomechanics

In the normal spine due to its curvature in various regions, C7 plumb line (C7PL) passes through the sacrum so that the head is centered over the pelvis-ball and socket hip joints and ankle joints. This configuration leads to the least muscular activities to maintain the spinal balance. For any reason like deformity, scoliosis, kyphosis, trauma, and/or surgery this optimal configuration gets disturbed requiring higher muscular activity to maintain the posture and balance. Several parameters like the thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), Hip- and leg position influence the sagittal balance and thus the optimal configuration of spinal alignment. Global sagittal imbalance is energy consuming and often painful compensatory mechanisms are developed, that in turn negatively influence the quality of life. This review looks at the clinical aspects of spinal imbalance, and the biomechanics of spinal balance as dictated by the deformities- ankylosing spondylitis, scoliosis and kyphosis; surgical corrections- pedicle subtraction osteotomies and long segment stabilizations and consequent postural complications like the proximal and distal junctional kyphosis. This review suggests several potential research topics as well.

Pelvic incidence measurement using a computed tomography data-based three-dimensional pelvic model

Objectives

To introduce a new method of pelvic incidence (PI) measurement based on three-dimensional (3D) pelvic models reconstructed from CT images and to report the normal distribution of PI in normal pelvic anatomy.

Methods

CT images of 320 subjects with normal pelvic anatomy who visited the Radiology Department between 2006 and 2017 were retrospectively selected and saved in Digital Imaging and Communications in Medicine (DICOM) format. A computerized method was employed to determine the bony landmarks required for the measurement of PI. To quantify the method’s accuracy and reliability, the intraclass correlation coefficient (ICC) was calculated. A subgroup of 30 DICOM files was randomly selected to perform a validation study. Three independent testers performed all procedures. All measurements were performed twice independently by the three testers on all 10 subjects with an interval of 2 weeks. Independent samples t tests were used to identify statistically significant differences in the PI value between sexes. Pearson correlation coefficient was employed to determine the relationship between PI and age.

Results

PI measurement using the new method resulted in an excellent intraobserver reliability (0.9612, range 0.8917–0.9893; p < 0.001) and interobserver reliability (0.9867, range 0.9611–0.9964; p < 0.001). PI was significantly different between sexes, with larger PI in women (p = 0.019). PI was significantly larger in the 40–80-year age group (45.94 ± 9.08°) than the < 40-year age group (43.50 ± 7.39°). We did not find any linear correlation between PI and age in the male (r = 0.140, p = 0.105) or female subgroup (r = 0.119, p = 0.107). A weak correlation between PI and age overall was observed (r = 0.142, p = 0.011).

Conclusion

Accurate PI measurement could be achieved by a CT data-based 3D pelvic model.

Effect of age and sex on lumbar lordosis and the range of motion. A systematic review and meta-analysis

Lumbar lordosis (LL) and the range of motion (RoM) are important physiological measurements when initiating any diagnosis and treatment plan for patients with low back pain. Numerous studies reported differences in LL and the RoM due to age and sex. However, these findings remain contradictory. A systematic review and meta-analysis were performed to synthesize mean values and the differences in LL and the RoM because of age and sex. The quality assessment tool for quantitative studies was applied to assess the methodological quality of the studies included. We identified 2372 papers through electronic (2309) and physical (63) searches. We assessed 218 full-text studies reporting measurements of LL or the RoM. In total, 65 studies were included, and a normative database for LL and the RoM is provided as supplementary material. Among these, 11 were included in the meta-analysis. LL and the RoM displayed non-monotonic variations with significant age and sex differences. Young females showed a significantly greater LL and the range of extension (RoE), whereas young males exhibited a greater range of flexion (RoF). Sex differences in the range of lateral bending (RoLB) were small but were significant for the axial rotation (RoAR). For the RoF, RoE and RoLB, differences because of age were significant among most of the age groups in both sexes, whereas for the RoAR, differences were significant only between the 20s vs the 30s-40s (males) and 40s vs 50s (females). Significant differences because of age/sex were identified. However, the age-dependent reduction in LL and the RoM was non-monotonic and differed in both sexes. These findings will help to better distinguish between functional deficits caused by spinal disorders and natural factors/conditions related to age and sex.

[The disputes in the radiographic measurements of sagittal balance and how to deal with them]

Objective

To review the process of radiographic measurements of sagittal balance and offer reference for the clinical practice.

Methods

The related literature of spino-pelvic sagittal parameters and their clinical application was reviewed and analyzed from the aspects such as the clinical application, the advantages and disadvantages, and how to use them effectively.

Results

All parameters have their advantages and disadvantages, and they are influenced by age and race. Sagittal vertical axis can only reflect the global balance, and T 1 pelvic angle which accounts for both spinal inclination and pelvic tilt can't be controlled in the surgery. The correction goal for western people may be not suitable for Chinese.

Conclusion

The parameters should be used wisely when evaluating the sagittal balance, the global balance and local balance should be considered together and the different groups of people need different correction goals.

Possible factors associated with sagittal malalignment recurrence after pedicle subtraction osteotomy

PURPOSE

This retrospective study investigates sagittal alignment after pedicle subtraction osteotomy (PSO). The purpose was to investigate factors associated with malalignment recurrence.

METHODS

Full spine radiographs were analyzed in 66 patients (average age 54.5 years, follow-up 3.8 years). Measurements were taken preoperatively, 3 months postoperatively, at follow-up: SVA C2 and C7, C2-C7 lordosis, T4-T12 kyphosis, L1-S1 lordosis, PSO lordosis, pelvic incidence, pelvic tilt, sacral slope. Follow-up CTs were screened for pseudarthrosis and gas in sacroiliac joints.

RESULTS

PSO lordosis increased from 11.8° to 40.8° (p < 0.0001) and kept stable. Lumbar lordosis increased from 28.6° to 57.7° (p < 0.0001) and decreased to 49.7° (p = 0.0008). Pelvic tilt decreased from 29.2° to 16.5° (p < 0.0001) and increased to 22.5° (p < 0.0001). SVA C7 decreased from 105.1 to 35.5 mm (p < 0.0001) and increased to 64.8 mm (p = 0.0005). Twenty-eight patients (42%) had an SVA C7 increase of more than 70 mm in the postoperative course: recurrence group. These patients were older: 62.8 years versus 52.3 years (p = 0.0031). Loss of lordosis was 11.9° (recurrence group) versus 5.0° (non-recurrence group). Eleven patients (17%) had pseudarthrosis. Pelvic incidence increased by 9.3° (recurrence group) versus 3.8° (non-recurrence group). In 23 patients (35%), pelvic incidence increased > 10°. Gas was evidenced in sacroiliac joints in 22 patients (33%).

CONCLUSION

Postoperative anterior malalignment recurrence may occur after PSO. Elderly patients were at risk of recurrence. Loss of lumbar lordosis linked to pseudarthrosis represented another factor. With malalignment recurrence, anterior trunk rotation and pelvic retroversion might additionally have augmented moments across sacroiliac joints with subsequent ligament laxity and pelvic incidence increase. These slides can be retrieved under Electronic Supplementary Material.

Are There Age- and Sex-related Differences in Spinal Sagittal Alignment and Balance Among Taiwanese Asymptomatic Adults?

BACKGROUND

Sagittal spinopelvic balance and proper sagittal alignment are important when planning corrective or reconstructive spinal surgery. Prior research suggests that people from different races and countries have moderate divergence; to the best of our knowledge, the population of Taiwan has not been studied with respect to this parameter.

QUESTIONS/PURPOSES

To investigate normal age- and sex-related differences in whole-spine sagittal alignment and balance of asymptomatic adults without spinal disorders.

METHODS

In this prospective study, we used convenience sampling to recruit asymptomatic volunteers who accompanied patients in the outpatient orthopaedic department. One hundred forty males with a mean age of 48 ± 19 years and 252 females with a mean age of 53 ± 17 years underwent standing lateral radiographs of the whole spine. For analysis, participants were divided in three groups by age (20 to 40 years, 41 to 60 years, and 61 to 80 years) and analyzed by sex (male and female). The following eight radiologic parameters were measured: sacral slope, pelvic tilt, pelvic incidence, thoracic kyphosis, lumbar lordosis, cervical lordosis, C2-C7 sagittal vertical axis, and C7-S1 sagittal vertical axis. Three observers performed estimations of the sagittal parameters twice, and the intraclass correlation coefficients for inter- and intraobserver variability were 0.81 and 0.83.

RESULTS

The mean pelvic incidence was 49° ± 12°; lumbar lordosis was smaller in the group that was 61 to 80 years old than in the groups that were 20 to 40 years and 41 to 60 years (95% CI of the difference, 4.50-13.64 and 1.00- 9.60; p < 0.001), while cervical lordosis was greater in the 61 to 80 years age group than the other two groups (95% CI of the difference, -14.64 to -6.57 and -11.57 to -3.45; p < 0.001). The mean C7-S1 sagittal vertical axis was 30 ± 29 mm, and there was no difference among the three groups and between males and females. Pelvic tilt was greater in the group 61 to 80 years old than the 20 to 40 years and 41 to 60 years age groups (95% CI of the difference, -10.81 to -5.42 and -7.15 to -2.08; p < 0.001), while sacral slope was larger in 61 to 80 years age group than in the 41 to 60 years group (95% CI of the difference, 0.79-6.25; p = 0.006). C7 slope was greater in 61 to 80 years age group than in the 20 to 40 years group (95% CI of the difference, -7.49 to -1.26; p = 0.002) and larger in 41 to 60 years age group than in 20 to 40 years group (95% CI of the difference, -6.31 to -0.05; p = 0.045). C2-C7 sagittal vertical axis was greater in males than in females (95% CI of the difference, 2.84-7.74; p < 0.001). C7 slope was negatively correlated with thoracic kyphosis (95% CI of the difference, -0.619 to 0.468; p < 0.001) and lumbar lordosis (95% CI of the difference, -0.356 to -0.223; p < 0.001), and positively correlated with pelvic incidence (95% CI of the difference, 0.058- 0.215; p < 0.001) and cervical lordosis (95% CI of the difference, 0.228 - 0.334; p < 0.001).

CONCLUSIONS

Normal values of the spinopelvic sagittal parameters vary by age and sex in Taiwanese individuals.

CLINICAL RELEVANCE

Pelvic incidence and sacral slope observed in this population seemed smaller than those reported in other studies of white populations; this seems important when considering spine surgery in Taiwanese patients. Future studies should include collection of whole body sagittal parameters of larger and more-diverse populations, and assessments of patients with symptomatic spinal disorders.

Sagittal lumbopelvic alignment in patients with low back pain and the effects of a high-load lifting exercise and individualized low-load motor control exercises-a randomized controlled trial

BACKGROUND CONTEXT

Assessment of posture and lumbopelvic alignment is often the main focus in the classification and treatment of patients with low back pain (LBP). However, little is known regarding the effects of motor control interventions on objective measures of lumbopelvic alignment.

PURPOSE

The primary aim of this study was to describe the variation of sagittal lumbopelvic alignment in patients with nociceptive mechanical LBP. The secondary aim was to compare the effects of a high-load lifting exercise (HLL) and low-load motor control exercises (LMC) on the change in lumbopelvic alignment with a special emphasis on patients with high and low degrees of lumbar lordosis (lu) and sacral angle (sa).

STUDY DESIGN

This study is a secondary analysis of a randomized controlled trial evaluating the effects of HLL and LMC.

PATIENT SAMPLE

Patients from the primary study, that is, patients categorized with nociceptive mechanical LBP, who agreed to participate in the radiographic examination were included (n=66).

OUTCOME MEASURES

Lateral plain radiographic images were used to evaluate lumbopelvic alignment regarding the lumbar lordosis and the sacral angle as outcomes, with posterior bend as an explanatory variable.

MATERIALS AND METHODS

The participants were recruited to the study from two occupational health-care facilities. They were randomized to either the HLL or the LMC intervention group and offered 12 supervised exercise sessions. Outcome measures were collected at baseline and following the end of intervention period 2 months after baseline. Between- and within-group analyses of intervention groups and subgroups based on the distribution of the baseline values for the lumbar lordosis and the sacral angle, respectively (LOW, MID, and HIGH), were performed using both parametric and non-parametric statistics.

RESULTS

The ranges of values for the present sample were 26.9-91.6° (M=59.0°, standard deviation [SD]=11.5°) for the lumbar lordosis and 18.2-72.1° (M=42.0°, SD=9.6°) for the sacral angle. There were no significant differences between the intervention groups in the percent change of eitheroutcome measure. Neither did any outcome change significantly over time within the intervention groups. In the subgroups, based on the distribution of respective baseline values, LOW_lu showed a significantly increased lumbar lordosis, whereas HIGH_sa showed a significantly decreased sacral angle following intervention.

CONCLUSIONS

This study describes the wide distribution of values for lumbopelvic alignment for patients with nociceptive mechanical LBP. Further research is needed to investigate subgroups of other types of LBP and contrast findings to those presented in this study. Our results also suggest that retraining of the lumbopelvic alignment could be possible for patients with LBP.

Focal disorders of the spine with compensatory deformities: how to define them

PURPOSE

In this paper, the authors propose classifying the epiphenomenon of spinal deformity in two different categories: structural deformity, when the main driver of the observed deformity is a fixed and stiff alteration of the spinal segments, and compensatory deformity, which includes cases where the observed deformity is due to focal abnormalities. This last category comprises, but is not limited to, spinal stenosis, spondylolisthesis, disc herniation, infection or tumor, hip disease or neurological disease (such as Parkinson's disease).

METHOD

Narrative review article.

RESULTS

We analyzed the focal diseases of the spine that may cause a compensatory deformity inducing adaptation in the unaffected part of the spine.

CONCLUSION

The compensatory mechanisms involved in adaptive deformity represent an attempt to maintain a global alignment, to escape from pain or to control body posture. These slides can be retrieved under Electronic Supplementary material.

Effect of Sagittal Balance on Risk of Falling after Lateral Lumbar Interbody Fusion Surgery Combined with Posterior Surgery

PURPOSE

To demonstrate the impact of correcting sagittal balance (SB) on functional outcomes of surgical treatment for degenerative spinal disease and actual falls via utilization of new minimally invasive lumbar fusion techniques via a lateral approach.

MATERIALS AND METHODS

From November 2011 to March 2015, we enrolled 56 patients who underwent minimally invasive lateral lumbar interbody fusion (LLIF) and matched 112 patients receiving decompression/postero-lateral fusion (PLF) surgery for lumbar spinal stenosis. According to SB status using C7-plumb line-distance (C7PL) and surgery type, patients were divided into three groups: SB PLF, sagittal imbalance (SI) PLF, and LLIF groups. We then compared their outcomes.

RESULTS

The mean C7PL was 6.2±13.6 mm in the SB PLF group, 72.9±33.8 mm in the SI PLF group, and 74.8±38.2 mm in the LLIF group preoperatively. Postoperatively, C7PL in only the LLIF group improved significantly (p=0.000). Patients in the LLIF group showed greater improvement in fall-related functional test scores than the SI PLF group (p=0.007 for Alternate-Step test, p=0.032 for Sit-to-Stand test). The average number of postoperative falls was 0.4±0.7 in the SB PLF group, 1.1±1.4 in the SI PLF group, and 0.8±1.0 in the LLIF group (p=0.041). Oswestry Disability Index and the Euro-QoL 5 dimension visual analogue scale scores also showed greater improvements in the LLIF group than in the SI PLF group at postoperative 1 year (p=0.003, 0.016).

CONCLUSION

Surgical correction of SI in patients with lumbar spinal stenosis using a combination of minimal invasive LLIF and posterior surgery achieved better surgical outcomes and a lower incidence of actual falls than PLF surgery.