Sagittal plane deformity: an overview of interpretation and management

Severity of degenerative lumbar spinal stenosis affects pelvic rigidity during walking

BACKGROUND CONTEXT

To understand the role of compensation mechanisms in the development and treatment of symptomatic degenerative lumbar spinal stenosis (DLSS), pelvic stability during walking should be objectively assessed in the context of clinical parameters.

PURPOSE

To determine the association among duration of symptoms, lumbar muscle atrophy, disease severity, pelvic stability during walking, and surgical outcome in patients with DLSS scheduled for decompression surgery.

STUDY DESIGN/SETTING

Prospective observational study with intervention.

PATIENT SAMPLE

Patients with symptomatic DLSS.

OUTCOME MEASURES

Oswestry Disability Index score; duration of symptoms; lumbar muscle atrophy; severity grade; pelvis rigidity during walking.

METHODS

Patients with symptomatic DLSS were analyzed on the day before surgery and 10 weeks and 12 months postoperatively. Duration of symptoms was categorized as: <2years, <5years, and >5years. Muscle atrophy at the stenosis level was categorized according to Goutallier. Bilateral cross-sectional areas of the erector spinae and psoas muscles were quantified from magnetic resonance imaging. Stenosis grade was assessed using the Schizas classification. Pelvic tilt was measured in standing radiographs. Pelvic rigidity during walking was assessed as root mean square of the pelvic acceleration in each direction (anteroposterior, mediolateral, and vertical) normalized to walking speed measured using an inertial sensor attached to the skin between the posterior superior iliac spine.

RESULTS

Body mass index but not duration of symptoms, lumbar muscle atrophy, pelvic rigidity, and stenosis grade explained changes in Oswestry Disability Index from before to after surgery. Patients with greater stenosis grade had greater pelvic rigidity during walking. Lumbar muscle atrophy did not correlate with pelvic rigidity during walking. Patients with lower stenosis grade had greater muscle atrophy and patients with smaller erector spinae and psoas muscle cross-sectional areas had a greater pelvis tilt.

CONCLUSIONS

Greater pelvic rigidity during walking may represent a compensatory mechanism of adopting a protective body position to keep the spinal canal more open during walking and hence reduce pain. Pelvic rigidity during walking may be a useful screening parameter for identifying early compensating mechanisms. Whether it can be used as a parameter for personalized treatment planning or outcome prognosis necessitates further evaluation.

PI and T9-SPI: New Predictive Factors for Increased Kyphosis of the Thoracolumbar Junction in Thoracolumbar/Lumbar Adolescent Idiopathic Scoliosis

Objectives: Studies have demonstrated that there is an increased thoracolumbar junction sagittal Cobb angle (TLJS) in thoracolumbar/lumbar adolescent idiopathic scoliosis (AIS) patients. The objectives were to ascertain the correlations between the spinopelvic alignments and TLJS and to explore potential predictive factors for hyperkyphotic TLJS in the sagittal plane in thoracolumbar/lumbar AIS. Methods: A total of 114 AIS patients with thoracolumbar/lumbar curve were included. Cobb angle, apical vertebrae rotation (AVR), thoracic kyphosis (TK), TLJS, lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), T1-spinopelvic inclination (T1-SPI), and T9-spinopelvic inclination (T9-SPI) were measured. After patients were organized into two subgroups based on TLJS, all parameters were compared between the two groups. Correlation analysis and multiple linear regression analysis were performed between the radiologic measurements and TLJS in all patients. Results: There was a significant difference between the non-kyphotic group and kyphotic group in mean Nash-Moe grade, TK, T9-SPI, PI, and SS. Correlation analysis showed that LL, PI, and SS were inversely associated with TLJS. TK, T9-SPI, and Nash-Moe grade were positively related to TLJS. The multiple linear regression analysis showed that TLJS could be predicted by the equation TLJS = -2.322 + 5.585 × Nash-Moe grade + 0.687 × T9-SPI - 0.208 × PI, with an adjusted R² of 0.410. Conclusion: TLJS was positively correlated with greater AVR in the coronal plane, greater T9-SPI in the sagittal plane and inversely associated with PI among patients with thoracolumbar/lumbar scoliosis. Spine surgeons should pay more attention to the degree of AVR, T9-SPI, and PI when dealing with thoracolumbar/lumbar scoliosis with thoracolumbar junction kyphosis.

Risk factors of low back pain and the relationship with sagittal vertebral alignment in Tanzania

Background

LBP is a common and serious problem affecting vast populations of the world. However, only few studies on LBP in sub-Saharan Africa have been conducted. Studies report that LBP and pelvic angle are interrelated, and African residents have a high pelvic tilt. The strategy to prevent LBP should focus on activities that promote holistic health. For that purpose, it is important to grasp the state of LBP and how it affects people’s lifestyle in Tanzania to clarify the direction of implementation of physiotherapy treatment and reduce the incidences of LBP among adults. This study aimed to investigate the prevalence and presentation of low back pain (LBP) and the relationship between anthropometric measurements and LBP among people in Moshi city, Kilimanjaro region Tanzania.

Methods

Following signing consent forms, participants were given questionnaires regarding LBP and then grouped accordingly into either asymptomatic or symptomatic cohorts. Anthropometric measurements of participants’ height, weight, curvature of the spine, and pelvic angle were obtained.

Results

A Mann-Whitney U test analysis showed a significant difference in pelvic angle, body mass index (BMI), and thoracic kyphosis angle between the asymptomatic group and the symptomatic group. No significant differences in lumbar lordosis angle or abdominal muscle strength were found between the two groups.

Conclusions

A person with symptomatic LBP in Tanzania has a large anteversion of the pelvic tilt and a thoracic kyphotic posture. This study shows a relationship between sagittal spinal alignment and LBP in Tanzania, which could allow for prospective identification of subjects prone to developing LBP in the future.

Evaluation of a new sagittal classification system in adolescent idiopathic scoliosis

PURPOSE

The purpose of the present study was to validate a new spinal sagittal classification.

METHODS

We retrospectively included 105 consecutive AIS patients who underwent posterior spinal fusion. Preoperative long-standing EOS radiographs were available on all patients. Patients were classified according to the four suggested sagittal patterns: type 1, 2a, 2b or 3. Several predetermined sagittal parameters were compared between the groups.

RESULTS

The mean preoperative Cobb angle was 64° ± 12°, and 73% of the patients were female. Of 105 patients, 51 were type 1, 14 were type 2a, one was type 2b and 39 were type 3. The distribution of the four sagittal patterns was significantly different compared with the original publication (p < 0.05). However, the two study populations were comparable in terms of Lenke and Roussouly types (p = 0.49 and 0.47, respectively). In our study population, the sagittal groups differed significantly in terms of thoracic kyphosis, length of thoracic and lumbar curves, lumbar lordosis, thoracic slope, C7 slope, pelvic incidence and sacral slope (p < 0.05).

CONCLUSION

The distribution of the four sagittal patterns varies between AIS cohorts. Type 2b was rare, which limits the clinical applicability. Contrary to the original publication, we found that the spinopelvic parameters lumbar lordosis, pelvic incidence and sacral slope were significantly different between the Abelin-Genevois types. Hence, the corrective surgical strategy may need to incorporate these spinopelvic parameters to achieve a balanced spine requiring a minimum of energy expenditure. These slides can be retrieved under Electronic Supplementary Material.

MODIFICATION OF THE SPINOPELVIC PARAMETERS WITH SURGICAL POSITIONING AND THE ROLE OF THE HIP

ABSTRACT Post-operative lumbar pain is related to alterations in the sagittal and spinopelvic parameters. A lumbar fusion that fails to maintain, or that worsens the physiological lordosis alters the sagittal balance. Objective: To analyze spinopelvic variation in different surgical positions. Methods: A prospective, analytical and comparative study of spinograms, lumbosacral radiographs in the surgical position over a 4-pole quadratus lumborum, and lumbosacral radiographs with quadratus lumborum and support in the knees. A sample of 129 patients, of both sexes, aged between 18 and 60 years, and presenting with lower back pain. Lumbar Lordosis (LL), Pelvic Tilt (PT), Pelvic Incidence (PI) and Sacral Slope (SS) were measured. Results: PI was the most stable parameter. With quadratus lumborum, a slight increase in PT, a decrease in SS and a significant reduction in LL were found. With quadratus lumborum and support in the knees, a decrease in PT and a slight increase in SS were found, while the LL value remained similar to that of the spinogram. Conclusion: The intraoperative position with hip flexion of between 40° and 45° over quadratus lumborum reduced LL to 10.52° in men and 16.21° in women, increased PT, and decreased SS. The intraoperative position with hip flexion of between 0° and 10° showed the same values as the reference spinogram. Level of Evidence II; Prospective comparative study.

Sagittal Balance in Adolescent Idiopathic Scoliosis Managed With Intraoperative Skull Femoral Traction

STUDY DESIGN

This is a retrospective cohort, single-center quality improvement study.

OBJECTIVES

To evaluate the effect of the intraoperative skull femoral traction (IOSFT) on sagittal balance in posterior spinal instrumentation (PSI) to manage scoliosis.

SUMMARY OF BACKGROUND DATA

IOSFT has been used routinely as an adjunct technique for facilitating PSI to manage scoliosis in our institution since 2010. Previous studies have raised concerns regarding the negative effect of IOSFT on lumbar lordosis.

MATERIALS AND METHODS

The medical records and radiographs of 113 patients with adolescent idiopathic scoliosis managed with single stage PSI were reviewed. Eighty-five patients were operated with IOSFT (traction group) and 28 patients were operated without traction (nontraction group). Patients who had double (anterior-posterior) approaches or nonidiopathic scoliosis were excluded. Sagittal balance and pelvic parameters at 2 years of postoperative follow-up were the primary outcome measures. Statistical analysis was done with R for statistical computing. Median values and interquartile range were compared between groups using Wilcoxon rank sum, Fischer exact, and Welch t tests. P-values of <0.05 were considered statistically significant.

RESULTS

No significant differences were found comparing postoperative lumbar lordosis in the nontraction group (54 degrees) with the traction group (53 degrees) (P=0.4953). No significant differences were found in postoperative sagittal vertical axis medians comparing both groups, with 17 mm in the nontraction group and 18 mm in the traction group (P=0.3994). No significant differences were found in postoperative pelvic parameters. The median pelvic incidence was 52 degrees in the nontraction group and 50 degrees in the traction group (P=0.2711).

CONCLUSIONS

According to our results, the use of IOSFT as an adjunct to facilitate PSI for managing adolescent idiopathic scoliosis had no measurable negative impact on sagittal balance in our IOSFT cohort.

Importance of Spinal Alignment in Primary and Metastatic Spine Tumors

Spinal alignment, particularly with respect to spinopelvic parameters, is highly correlated with morbidity and health-related quality-of-life outcomes. Although the importance of spinal alignment has been emphasized in the deformity literature, spinopelvic parameters have not been considered in the context of spine oncology. Because the aim of oncologic spine surgery is mostly palliative, consideration of spinopelvic parameters could improve postoperative outcomes in both the primary and metastatic tumor population by taking overall vertebral stability into account. This review highlights the relevance of focal and global spinal alignment, particularly related to spinopelvic parameters, in the treatment of spine tumors.

Spinopelvic parameters in patients with lumbar degenerative disc disease, spondylolisthesis, and failed back syndrome: Comparison vis-à-vis normal asymptomatic population and treatment implications

Background:

Most of the literature on role of spinopelvic parameters in various lumbar spine pathologies has been based on studies done on Caucasian population.

Aims and Objectives:

The present study attempts to establish a database of measurements of the sagittal profile of spine in asymptomatic Indian population and their comparison with subjects having various lumbar spine pathologies.

Materials and Methods:

We performed a prospective case control study at All India Institute of Medical Sciences, New Delhi in which we enrolled 109 patients and 22 healthy asymptomatic subjects in 2 years from 2015 to 2017. All patients underwent standing lateral radiographs of the pelvis and the entire spine and various spino-pelvic parameters were measured using Surgimap software.

Results:

The mean Pelvic incidence (PI) in the asymptomatic individuals was 49.29 ± 5.95° which was significantly lower when compared with patients of chronic low backache (53.96 ± 9.47, P-<0.001), lumbar listhesis (59.4 ± 21.33, P-<0.001) and failed back surgery syndrome (56.7 ± 8.21, P-<0.001). The mean Pelvic Tilt (PT) in healthy subjects was 14.3±4.08° which was significantly lower when compared with patients of lumbar listhesis (23.35 ± 14.03, P-<0.001) and failed back surgery syndrome (22.8 ± 8.09, P-<0.001). Sacral slope (SS) and sagittal vertical axis (SVA) offset did not show any statistically significant difference. The mean Lumbar lordosis (LL) measured in healthy individuals was 42.5 ± 7.89° which was significantly lower when compared with patients of lumbar listhesis (46.24 ± 19.24, P-0.04) and failed back surgery syndrome (45.12 ± 6.87, P-0.05).

Conclusion:

PT and PI showed statistically significant difference in subjects having lumbar spondylolisthesis and failed back surgery syndrome as compared to healthy asymptomatic subjects.

Prehabilitation for patient positioning: pelvic exercises assist in minimizing inter-fraction sacral slope variability during radiation therapy

Reproducible patient positioning is essential for precision in radiation therapy (RT) delivery. We tested the hypothesis that a structured daily pre-treatment stretching regimen is both feasible and effective for minimizing variability in positioning, as measured by sacral slope angles (SSA). Eight female subjects undergoing pelvic radiotherapy performed a structured daily hip exercise regimen (extension and external rotation) immediately prior to both simulation imaging and daily treatment, throughout their RT course. This exercising cohort was compared to a retrospective review of 20 subjects (17 women and 3 men) undergoing RT, who had usual care. SSA measurements from daily pre-treatment imaging were compared to SSA measurements from the simulation CT. The average variation in SSA among the intervention subjects was 0.91° (± 0.58°), with a range among subjects of 0.57°-1.27°. The average variation for the control subjects was 2.27° (± 1.43°), ranging 1.22°-5.09°. The difference between the two groups was statistically significant (p = 0.0001). There was a statistically significant SSA variation between groups at each week of treatment. There was no significant variation among the intervention subjects between week 1 and later weeks, whereas subjects in the control group demonstrated significant SSA variation between week 1 and later weeks. We demonstrated a significant decrease in the variability of SSA by implementing a simple pre-treatment exercise program, while control subjects exhibited increasing variation in SSA over the course of treatment. We conclude that there is a potential benefit of prehabilitation during pelvic RT; however, a larger randomized control trial is required to confirm the findings.Clinical Trial: This research project was approved by the University of Massachusetts Medical School IRB (IRB ID H00012353) on January 21, 2017. The study is listed on ClinicalTrials.gov, provided by the U.S. National Library of Medicine, found with identifier NCT03242538.

Spinopelvic Compensatory Mechanisms for Reduced Hip Motion (ROM) in the Setting of Hip Osteoarthritis

STUDY DESIGN

Retrospective review from a single institution.

OBJECTIVE

To investigate the effect of hip osteoarthritis (OA) on spinopelvic compensatory mechanisms as a result of reduced hip range of motion (ROM) between sitting and standing.

SUMMARY OF BACKGROUND DATA

Hip OA results in reduced hip ROM and contracture, causing pain during postural changes. Hip flexion contracture is known to reduce the ability to compensate for spinal deformity while standing; however, the effects of postural spinal alignment change between sitting and standing is not well understood.

METHODS

Sit-stand radiographs of patients without prior spinal fusion or hip prosthesis were evaluated. Hip OA was graded by Kellgren-Lawrence grades and divided into low-grade (LOA; grade 0-2) and severe (SOA; grade 3 or 4) groups. Radiographic parameters evaluated were pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, thoracic kyphosis (TK), SVA, T1-pelvic angle (TPA), T10-L2, proximal femoral shaft angle (PFSA), and hip flexion (PT change-PFSA change). Changes in sit-stand parameters were compared between LOA and SOA groups.

RESULTS

548 patients were included (LOA = 311; SOA = 237). After propensity score matching for age, body mass index, and PI, 183 LOA and 183 SOA patients were analyzed. Standing analysis demonstrated that SOA had higher SVA (31.1 vs. 21.7), lower TK (-36.2 vs. -41.1), and larger PFSA (9.1 vs. 7.4) (all p < .05). Sitting analysis demonstrated that SOA had higher PT (29.7 vs. 23.3), higher PI-LL (21.6 vs. 12.4), less LL (31.7 vs. 41.6), less TK (-33.2 vs. -38.6), and greater TPA (27.9 vs. 22.5) (all p < .05). SOA had less hip ROM from standing to sitting versus LOA (71.5 vs. 81.6) (p < .05). Therefore, SOA had more change in PT (15.2 vs. 7.3), PI-LL (20.6 vs. 13.7), LL (-21.4 vs. -13.1), and T10-L2 (-4.9 vs. -1.1) (all p < .001), allowing the femurs to change position despite reduced hip ROM. SOA had greater TPA reduction (15.1 vs. 9.6) and less PFSA change (86.7 vs. 88.8) compared with LOA (both p < .001).

CONCLUSIONS

Spinopelvic compensatory mechanisms are adapted for reduced hip joint motion associated with hip OA in standing and sitting.

LEVEL OF EVIDENCE

Level III.

Imaging in Spine Surgery: Current Concepts and Future Directions

OBJECTIVE

To review and highlight the historical and recent advances of imaging in spine surgery and to discuss current applications and future directions.

METHODS

A PubMed review of the current literature was performed on all relevant articles that examined historical and recent imaging techniques used in spine surgery. Studies were examined for their thoroughness in description of various modalities and applications in current and future management.

RESULTS

We reviewed 97 articles that discussed past, present, and future applications for imaging in spine surgery. Although most historical approaches relied heavily upon basic radiography, more recent advances have begun to expand upon advanced modalities, including the integration of more sophisticated equipment and artificial intelligence.

CONCLUSIONS

Since the days of conventional radiography, various modalities have emerged and become integral components of the spinal surgeon's diagnostic armamentarium. As such, it behooves the practitioner to remain informed on the current trends and potential developments in spinal imaging, as rapid adoption and interpretation of new techniques may make significant differences in patient management and outcomes. Future directions will likely become increasingly sophisticated as the implementation of machine learning, and artificial intelligence has become more commonplace in clinical practice.

Restoring the ideal Roussouly sagittal profile in adult scoliosis surgery decreases the risk of mechanical complications

PURPOSE

There are still no data proving whether restoring the ideal sagittal profile (according to Roussouly classification) in adult scoliosis (AS) patients leads to any additional benefit, especially regarding mechanical complications.

METHODS

Retrospective analysis of operated AS patients recorded in a prospective multicenter database. Demographic and radiographic (preoperative and 6-week postoperative) data were analyzed. Patients with and without mechanical complications were compared looking especially at the surgical restoration of the ideal (based on Pelvic Incidence) sagittal profile. Univariate and multivariate analysis was performed to identify causes of mechanical complications at 2-year minimum follow-up.

RESULTS

Ninty-six AS patients were analyzed. Thirty-nine patients suffered a mechanical complication (18 PJK, 11 pseudoarthrosis, 10 screw pull-out), and 57 patients had no mechanical complications. Postoperatively, 72% of patients not matching the ideal Roussouly-type suffered mechanical complications compared to 15% of matched patients (P < 0.001). Univariate analysis showed that older patients 64.9 ± 13 versus 40.7 ± 15.6 years (P < 0.001), higher postoperative Global Tilt (27° vs. 14.7°) and Pelvic Tilt (25° vs. 16°) (P < 0.001), upper instrumented vertebra at the thoracolumbar junction (62% vs. 21%) (P < 0.001), fixation to the Iliac (76% vs. 6%) (P < 0.001), and postoperative Roussouly-type mismatch (72% vs. 15%) (P < 0.001) significantly increased the rate of mechanical complications. Multivariate logistic regression analysis selected: postoperative Roussouly-type mismatch (OR = 41.9; 95%CI = 5.5-315.7; P < 0.001), iliac instrumentation (OR = 19.4; 95%CI = 2.6-142.5; P = 0.004), and age (OR = 1.1; 95%CI = 1.02-1.16; P = 0.004), as the most important variables.

CONCLUSIONS

Adult scoliosis surgery should restore the ideal Roussouly sagittal profile to decrease the rate of mechanical complications, especially in patients older than 65, instrumented to the pelvis. These slides can be retrieved under Electronic Supplementary Material.

Sagittal Spinal Morphotype Assessment in Dressage and Show Jumping Riders

CONTEXT

Previous research has analyzed how the sport influences sagittal spinal curvatures in young athletes and has found that spinal curves may be modified as a consequence of repeated movement patterns and postures of each discipline.

OBJECTIVE

To analyze sagittal spinal alignment by equestrian discipline and its relation to training load, and to describe "sagittal integrative morphotype" in young riders.

DESIGN

Observational descriptive study.

SETTING

Training room.

PARTICIPANTS

A total of 23 riders (aged 9-17 y)-13 dressage riders (3 males and 10 females) and 10 show jumping riders (5 males and 5 females)-participated voluntarily.

MAIN OUTCOME MEASURES

Mann-Whitney U test was applied to determine differences between riders' characteristics (gender, discipline, and training load) and spine variables.

RESULTS

According to normality ranges for spinal curves, females showed an increase for lumbar curvature in standing position. It was found that show jumping riders manifested an increment in thoracic and lumbar curves while standing and an increase in the thoracic curvature in slump sitting. Statistically significant differences were found when lumbar curvature, "sit and reach" distance, and lumbo-horizontal angle in flexion were analyzed by gender in "sit and reach" test. No statistical significant differences were found when spinal curves in each position were analyzed depending on the training load. With regard to "sagittal integrative morphotype," all riders presented a hyperkyphotic dorsal morphotype no matter what their discipline. As for the lumbar curve, dressage and show jumping riders presented a functional hyperkyphotic morphotype.

CONCLUSIONS

It is important to note that many riders presented a sagittal imbalance for the thoracic and lumbar curves. Therefore, as the sagittal spinal misalignments persist and worsen over time, exercise programs to prevent or rehabilitate these imbalances in young riders will be needed. The "sagittal integrative morphotype" assessment is an essential tool in order to identify the spinal misalignment.

Correlation of tilt of the anterior pelvic plane angle with anatomical pelvic tilt and morphological configuration of the acetabulum in patients with developmental dysplasia of the hip: a cross-sectional study

Background

It was previously reported that pelvises with developmental dysplasia of the hip are tilted anteriorly, which increases bony coverage of the femoral head. This study aimed to investigate the correlation between anatomical parameters of the pelvis such as pelvic incidence and anatomical pelvic tilt and functional parameters of the spine and pelvis such as tilt of the anterior pelvic plane.

Methods

We examined 84 female patients with bilateral developmental dysplasia of the hip who had undergone curved periacetabular osteotomy at author’s institution. Radiographs of the thoracic to lumbar spines and the pelvis were obtained in the standing position to measure spino-pelvic parameters before surgery. Morphological parameters of the acetabulum such as the anterior center-edge (CE) angle, posterior CE angle, lateral CE angle, and acetabular anteversion were measured using a preoperative three-dimensional pelvic model reconstructed from computed tomography images. Pearson’s correlation analysis was conducted to evaluate the relationship of these parameters.

Results

With regard to correlations between pelvic incidence (PI) and other parameters, the sacral slope (SS) value (r = 0.666) was the highest among functional parameters and the anatomical-SS value (r = 0.789) was the highest among morphological parameters. There were moderate correlations of the anterior pelvic plane angle (APPA) with pelvic tilt (PT) (r = − 0.594) and anatomical-PT (r = 0.646). With regard to correlations between spino-pelvic parameters and bony morphological parameters of the acetabulum, there was a moderate correlation between anatomical-PT and acetabular anteversion (AA) (r = 0.424). There were moderate correlations of APPA with the anterior CE angle (r = − 0.478), posterior CE angle (r = 0.432), and AA (r = 0.565). APPA had a stronger correlation with anatomical-PT (r = 0.646) than with AA.

Conclusions

The tilt of the pelvis may be more dependent on anatomical-PT, a morphological parameter of the pelvis, than the lateral CE angle, anterior CE angle, posterior CE angle, and acetabular anteversion on bony coverage of the acetabulum. This study is the first to investigate the correlation between functional parameters of the pelvis and spine and morphological parameters of the pelvis and acetabulum besides PI.

Sagittal spinal parameters after en bloc resection of mobile spine tumors

BACKGROUND CONTEXT

En bloc resection and reconstruction (EBR) in patients with spinal malignancy aims to achieve local disease control. This is an invasive procedure with significant alterations of the physiological anatomy and subsequently, the spino-pelvic alignment. Sagittal spinal parameters are useful measurements to objectively identify disproportionate alignment on a radiograph. In the field of spinal deformities, there is increasing evidence for a relationship between sagittal alignment and patient reported outcomes.

PURPOSE

To determine sagittal spino-pelvic alignment after EBR in patients with spinal malignancies and the effect of these parameters on surgical and patient reported outcomes.

STUDY DESIGN

A retrospective case series.

METHODS

We included 35 patients who underwent EBR for spinal malignancies between 2000 and 2018. Radiographic measurements were performed using semi-automatic software; the parameters included were pelvic incidence (PI), sacral slope, pelvic tilt (PT), global tilt and lumbar lordosis. We calculated PI-based Global Alignment and Proportion (GAP) scores and prospective patient reported outcome scores Patient-Reported Outcome Measurement Information System-Physical Function (PROMIS-PF) were used.

RESULTS

Twenty-one (60%) patients filled out the PROMIS-PF score at a median of 16 months (Interquartile Range (IQR) 4-108) after surgery with a median score of 39 (IQR 32-42), the median GAP score was 7 (IQR 5-9). Bivariate analysis showed no statistically significant relationship between GAP score and instrumentation failure or need for revision surgery. Multivariable analysis of GAP score and PROMIS-PF score corrected for local disease recurrence showed a statistically significant correlation coefficient of -1.721 (p=.026; 95%CI=-3.216, -0.226).

CONCLUSION

In this cohort, all patients had a moderate or severe disproportioned spinal alignment after EBR and reconstruction surgery. The degree of sagittal spino-pelvic misalignment after EBR for spinal malignancies seems to be associated with patient reported health status in terms of PROMIS-PF scores. Further research with a larger patient cohort and standardized imaging and follow-up protocols is necessary in order to accurately use sagittal alignment as a predictive value for instrumentation failure and revision surgery.

Reduction of thoraco-lumbar junctional kyphosis, posterior sagittal balance, and increase of lumbar lordosis and sacral inclination by Chiropractic BioPhysics® methods in an adolescent with back pain: a case report

[Purpose] To present the structural improvement of an excessive junctional thoracolumbar kyphosis and related biomechanical parameters in an adolescent. [Participant and Methods] A 16 year old female presented with chronic back pains. Radiographic assessment revealed excessive posterior sagittal balance and thoracolumbar kyphosis and reduced lumbar lordosis and sacral inclination. Chiropractic BioPhysics® technique including mirror image®, anterior thoracic translation and thoracolumbar hyperextension traction was performed as well as spinal manipulation and postural exercises over an 8-week period. [Results] After 24 in-office treatments and a daily home program the patient reported a minimization of back pains and a better mood. Follow-up X-rays demonstrated a 48 mm reduction of posterior sagittal balance, a 22° reduction of thoracolumbar kyphosis, an 11° increase in lumbar lordosis, and a 10° increase in sacral inclination. [Conclusion] This is the first case documenting the non-surgical reduction of excessive thoracolumbar junctional kyphosis and related biomechanical parameters in an adolescent. Precise analysis of radiologic assessment for adolescents presenting with back pains is advised and are safe for the screening of postural disorders. There is a growing evidence base for the Chiropractic BioPhysics® technique approach in the correction of lumbar spine disorders; more research is encouraged to further evaluate this unique treatment.

Predictors of Poor Global Alignment and Proportion Score After Surgery for Adult Spinal Deformity

STUDY DESIGN

Retrospective observational study of a cohort of consecutive patients.

OBJECTIVE

To determine 1) the correlation between clinical and radiographic outcomes and Global Alignment and Proportion (GAP) score, and 2) which preoperative parameters predominantly influence the risk for poor GAP scores.

SUMMARY OF BACKGROUND DATA

Although numerous investigators have indicated their criteria for sagittal correction, it is still not unusual to observe poor outcome or complications even after ideal correction. The recently developed GAP score indicates spinopelvic alignment and setting surgical goals according to the score might decrease the prevalence of mechanical complications. However, there is no clear evidence of correlation between the GAP score and clinical outcomes, or which patient factors are preoperative predictors of poor postoperative GAP score.

METHODS

We included 128 consecutive patients treated with spinal correction surgery who had a minimum 2-year follow-up. The correlations between clinical outcomes, increased proximal junctional angle, and GAP score were determined. Univariate and multivariate logistic regression analyses were conducted to clarify potential preoperative risk factors for poor GAP score.

RESULTS

Based on total GAP score, 32 (25%) patients were grouped into proportioned, 50 (39.1%) into moderately disproportioned, and 44 (34.3%) into severely disproportioned spinopelvic alignment. Our present study showed a significantly positive correlation between Oswestry Disability Index, increased proximal junctional angle 2 years after surgery, and total GAP score. Uni and multivariate regression analysis showed a large global tilt was a risk factor for a poor GAP score and that the risk for a poor GAP score increased with ageing.

CONCLUSIONS

Because GAP score correlated with Oswestry Disability Index and increased proximal junctional angle 2 years after surgery, GAP score might define targets for sagittal spinopelvic alignment for favorable outcomes of corrective spinal surgery. A large preoperative global tilt is a potential predictor of poor postoperative GAP score.

LEVEL OF EVIDENCE

3.

Relationships between Spinal Sarcopenia and Spinal Sagittal Balance in Older Women

Background

Spinal sarcopenia is receiving renewed attention as a cause of spinal sagittal imbalance. However, the relationships between spinal sarcopenia and spinal sagittal balance (SSB) have not been thoroughly investigated. We evaluated the relationships between SSB parameters and sarcopenic indices with lumbar paraspinal muscle (LPM) quantity and strength in healthy older adults.

Methods

Twenty-four healthy community-dwelling older women were enrolled. Demographic variables, conventional sarcopenic indices, isometric back muscle strength, and SSB parameters, as well as results of functional examinations and lumbar spine computed tomography scan with LPM cross-sectional area (CSA) and density assessments, were examined. The independent effect on the sum of the total LPM CSA was determined using multivariable regression analysis adjusted for age, appendicular skeletal muscle mass, gait speed, handgrip strength, back extensor strength, and pelvic tilt (PT) angle.

Results

PT angle was significantly correlated with the sum of the total LPM CSA and mean LPM density (r=-0.502, p=0.015 and r=0.504, p=0.014, respectively). Furthermore, PT angle was an independent factor for the sum of the total LPM CSA (β=-0.610, p=0.021) in the multivariate regression models (R²=0.320).

Conclusion

Our data suggest that PT angle was significantly correlated with LPM CSA in healthy older women. To our knowledge, this is the first report to investigate the relationships of sarcopenic indices and spinal muscle degeneration with SSB.

Assessment and management of adult spinal deformities

Adult spinal deformity is a complex condition, increasing in prevalence, and occurring in a patient population in which it poses unique challenges. This review provides an overview of adult spinal deformity with a particular focus on its clinical evaluation, radiological assessment and classification, reviewing the current literature and amalgamating this with the authors' clinical experience.

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

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

SAGITTAL BALANCE IN ADOLESCENT IDIOPATHIC SCOLIOSIS

ABSTRACT Objective The objective of this study is to achieve a better understanding of the parameters that influence sagittal balance in a population with adolescent idiopathic scoliosis (AIS). Methods A retrospective study of 80 patients with adolescent idiopathic scoliosis (AIS) was conducted. The parameters evaluated were: age, sex, pelvic incidence (PI), sacral slop (SS), pelvic tilt (PT), sagittal balance (SB), coronal balance (CB), lumbar lordosis (LL), thoracic kyphosis (TK) divided into upper (between T1 and T5) and lower (between T5 and T12), cervical spine alignment (CSA), and Cobb’s coronal angle (CCA) of primary scoliotic curvature. Results Regarding the sagittal balance, this study demonstrated a significant statistical positive correlation with cervical shape (p<0.01) and upper thoracic kyphosis (from T1 to T5) (p<0.05), but not with the other variables. LL had a strong influence on lower thoracic curvature (from T5 to T12) and was strongly influenced by the PI and SS. Conclusions Sagittal balance is a parameter that is influenced by multiple factors. In fact, it is closely related to cervical shape and the upper thoracic curvature (from T1 to T5), which in turn, is closely linked to the severity of the scoliotic kyphosis. The Cobb angle of the lower thoracic spine (from T5 to T12) is more closely correlated with the angle of lumbar lordosis than with the upper thoracic kyphosis (from T1 to T5). Level of evidence IV; Case Series.

Anterior and Posterior Fusion for Large, Rigid Idiopathic Scoliosis: Does Implant Density Matter?

BACKGROUND

Despite advancements in surgical techniques, controversy remains regarding the optimal implant density for the correction of idiopathic scoliosis. Recent evidence has suggested that equivalent radiographic and clinical outcomes can be achieved with lower implant densities for those with moderate curves and good flexibility. Among the experts, the consensus has continued that higher implant densities should be used for larger, stiffer curves. The purpose of the present study was to compare the radiographic results between high-implant density (HID) and low-implant density (LID) constructs in patients with large (>65°), rigid (<50% flexibility) curves who had undergone anterior release and posterior spinal fusion.

METHODS

We reviewed the idiopathic scoliosis cases performed at a single institution from 2006 to 2014. Only those meeting the inclusion criteria were selected. The patients were divided into HID and LID groups. The postoperative radiographs were compared for coronal correction, thoracic kyphosis, pelvic tilt, lumbar lordosis, and sagittal vertical axis.

RESULTS

A statistically significant improvement in coronal correction was detected in the HID group at all follow-up points (final follow-up: HID, 81.1% vs. LID, 70.4%; P = 0.01). When preoperative thoracic kyphosis was considered, no differences were found between the 2 groups. No differences were found in the other sagittal parameters.

CONCLUSION

In patients with large, rigid idiopathic scoliosis undergoing anterior release and posterior spinal fusion, a small, but statistically, significant improvement in the coronal Cobb angle was seen. It remains to be determined whether this small difference in radiographic correction will have any influence on the clinical outcome.

Neurologic Injury in Complex Adult Spinal Deformity Surgery: Staged Multilevel Oblique Lumbar Interbody Fusion (MOLIF) Using Hyperlordotic Tantalum Cages and Posterior Fusion Versus Pedicle Subtraction Osteotomy (PSO)

STUDY DESIGN

A retrospective review of prospectively collected data.

OBJECTIVE

The aim of this study was to determine the safety of MOLIF versus PSO.

SUMMARY OF BACKGROUND DATA

Complex adult spinal deformity (CASD) represents a challenging cohort of patients. The Scoli-RISK-1 study has shown a 22.18% perioperative risk of neurological injury. Restoration of sagittal parameters is associated with good outcome in ASD. Pedicle subtraction osteotomies (PSO) is an important technique for sagittal balance in ASD but is associated with significant morbidity. The multilevel oblique lumbar interbody fusion (MOLIF) is an extensile approach from L1 to S1.

METHODS

Single surgeon series from 2007 to 2015. Prospectively collected data. Scoli-RISK-1 criteria were refined to only include stiff or fused spines otherwise requiring a PSO. Roentograms were examined preoperatively and 2 year postoperatively. Primary outcome measure was the motor decline in American Spinal Injury Association (ASIA) at hospital discharge, 6 weeks, 6 months, and 2 years. Demographics, blood loss, operative time, spinopelvic parameters, and spinal cord monitoring (SCM) events.

RESULTS

Sixty-eight consecutive patients were included in this study, with 34 patients in each Group. Group 1 (MOLIF) had a mean age 62.9 (45-81) and Group 2 (PSO) had a mean age of 66.76 years (47-79); 64.7% female versus PSO 76.5%; Body Mass Index (BMI) Group 1 (MOLIF) 28.05 and Group 2 (PSO) 27.17. Group 1 (MOLIF) perioperative neurological injury was 2.94% at discharge but resolved by 6 weeks. Group 2 (PSO) had five neurological deficits (14.7%) with no recovery by 2 years. There were four SCM events (SCM). In Group 1 (MOLIF), there was one event (2.94%) versus three events (8.88%) in Group 2 (PSO).

CONCLUSION

Staged MOLIF avoids passing neurological structures or retraction of psoas and lumbar plexus. It is safer than PSO in CASD with stiff or fused spines with a lower perioperative neurological injury profile. MOLIF have less SCM events, blood loss, and number of levels fused.

LEVEL OF EVIDENCE

3.

Adult spinal deformity

Adult spinal deformity affects the thoracic or thoracolumbar spine throughout the ageing process. Although adolescent spinal deformities taken into adulthood are not uncommon, the most usual causes of spinal deformity in adults are iatrogenic flatback and degenerative scoliosis. Given its prevalence in the expanding portion of the global population aged older than 65 years, the disorder is of growing interest in health care. Physical examination, with a focus on gait and posture, along with radiographical assessment are primarily used and integrated with risk stratification indices to establish optimal treatment planning. Although non-operative treatment is regarded as the first-line response, surgical outcomes are considerably favourable. Global disparities exist in both the assessment and treatment of adults with spinal deformity across countries of varying incomes, which represents an area requiring further investigation. This Seminar presents evidence and knowledge that represent the evolution of data related to spinal deformity in adults over the past several decades.

Hypertension Is Related to Positive Global Sagittal Alignment: A Cross-Sectional Cohort Study

Study Design

Cross-sectional cohort study.

Purpose

This study aimed to investigate the relationship between hypertension and spino-pelvic sagittal alignment in middle-aged and elderly individuals.

Overview of Literature

Positive global sagittal alignment is associated with poor health-related quality of life. Hypertension is associated with tissue microcirculation disorders of the skeletal muscle. We hypothesized that hypertension may be involved in positive global sagittal alignment.

Methods

In this institutional review board-approved study, 655 participants (262 men and 393 women; mean age, 72.9 years; range, 50–92 years) who underwent musculoskeletal screening in Toei town, Aichi, Japan were included. Whole spine and pelvic radiographs were taken, and radiographic parameters (thoracic kyphosis, lumbar lordosis, pelvic tilt, sacral slope, pelvic incidence, and sagittal vertical axis [SVA]) were measured using an image-analysis software. Hypertension was assessed using the standard criteria. The study participants were divided into three subgroups as per age (50–64 years, 65–74 years, and ≥75 years). We examined the differences in the radiographic parameters of those with and without hypertension in each age subgroup.

Results

In each age subgroup, there was no significant difference in the age and sex of those with and without hypertension. SVA was significantly shifted forward in the hypertension group than in the non-hypertension group in those aged 50–64 years old (32.4 mm vs. 16.0 mm, p=0.018) and in those aged 65–74 years old (42.7 mm vs. 30.6 mm, p=0.012). There was no significant difference between the hypertension and non-hypertension groups in terms of the alignment of the lumbar and thoracic spine in all the subgroups. In multivariate analysis, hypertension was a significant independent factor of forward-shifted SVA (standardized beta 0.093, p=0.015).

Conclusions

This study showed that hypertension was associated with forward-shifted global sagittal alignment.

Cervical Laminectomy With or Without Lateral Mass Instrumentation: A Comparison of Outcomes

STUDY DESIGN

Narrative review.

BACKGROUND

Cervical decompressive laminectomy is a common posterior approach for addressing multilevel cervical spondylotic myelopathy. However, there is a concern that cervical laminectomy can lead to kyphotic deformity with subsequent neurological decline. In this context, cervical laminectomy with fusion using lateral mass instrumentation has become increasingly utilized with the aim of reducing the risk of developing postoperative kyphotic deformity, which is thought to predispose to poorer neurological outcomes in the long term.

OBJECTIVE

To compare the evidence for stand-alone cervical laminectomy with laminectomy with posterior fusion in terms of clinical outcomes and the incidence of adverse events, particularly the development of postoperative cervical kyphosis.

MATERIAL AND METHODS

Initial Medline search using MeSH terms yielded 226 articles, 23 of which were selected. An additional PubMed search and the reference list of individual papers were utilized to identify the remaining papers of relevance.

RESULTS

Cervical laminectomy both with and without fusion offers effective decompression for symptomatic multilevel cervical spondylotic myelopathy. The incidence of postlaminectomy kyphosis is lower following posterior fusion; however, there seems to be no clinical-radiologic correlation given that patients who develop postoperative kyphosis often do not progress to clinical myelopathy. Furthermore, there are specific additional risks of posterior instrumentation that need to be considered.

CONCLUSION

In carefully selected patients with normal preoperative cervical sagittal alignment, stand-alone cervical laminectomy may offer acceptably low rates of postoperative kyphosis. In patients with preoperative loss of cervical lordosis and/or kyphosis, posterior fusion is recommended to reduce the risk of progression to postoperative kyphotic deformity, bearing in mind that radiologic evidence of kyphosis may not necessarily correlate with poorer clinical outcomes. Furthermore, the specific risks associated with posterior fusion (instrumentation failure, pseudarthrosis, infection, C5 nerve root palsy, and vertebral artery injury) need to be considered and weighed up against potential benefits.

Comparative study of multilevel posterior interbody fusion plus anterior longitudinal ligament release versus classic multilevel posterior interbody fusion in the treatment of adult spinal deformities

OBJECTIVE

Sagittal imbalance and loss of lumbar lordosis are the main drivers of functional disability in adult degenerative scoliosis. The main limitations of the classic posterior lumbar interbody fusion technique are increased risk of neurological injury and suboptimal correction of the segmental lordosis. Here, the authors describe the radiological results of a modified posterior lumbar interbody fusion and compare the results with a historical cohort of patients.

METHODS

Eighty-two consecutive patients underwent surgical treatment for degenerative scoliosis/kyphosis in a single tertiary referral center for complex spinal surgery. Fifty-five patients were treated using the classic multilevel posterior lumbar interbody fusion (MPLIF) technique and 27 were treated using the modified MPLIF technique to include a release of the anterior longitudinal ligament (ALL) and the annulus. A radiographic review of both series of patients was performed by two independent observers. Functional outcomes were obtained, and patients were registered in the European Spine Tango registry.

RESULTS

The mean L4-5 disc angle increased by 3.14° in the classic MPLIF group and by 12.83° in MPLIF plus ALL and annulus release group. The mean lumbar lordosis increased by 15.23° in the first group and by 25.17° in the second group. The L4-S1 lordosis increased on average by 4.92° in the classic MPLIF group and increased by a mean of 23.7° in the MPLIF plus ALL release group when both L4-5 and L5-S1 segments were addressed. There were significant improvements in the Core Outcome Measures Index and EQ-5D score in both groups (p < 0.001). There were no vascular or neurological injuries observed in either group.

CONCLUSIONS

The authors' preliminary results suggest that more correction can be achieved at the disc level using posterior-based ALL and annulus release in conjunction with posterior lumbar interbody fusion. They demonstrate that ALL and annulus release can be performed safely using a posterior-only approach with minimal risk of vascular injury. However, the authors recommend that this approach should only be used by surgeons with considerable experience in anterior and posterior spinal surgery.

Knee-Hip-Spine Syndrome: Improvement in Preoperative Abnormal Posture following Total Knee Arthroplasty

An ergonomic upright body posture is maintained by the alignment of the spine, pelvis, and lower extremities, and the muscle strength of body trunk and lower extremities. The posture varies with age because of the degenerative changes in the involved structures and the weakening of the muscles. The compensatory mechanisms underlying these changes have recently been evaluated, and the loss of lumbar lordosis results in spinal kyphosis, pelvic retroversion, hip extension, knee flexion, and ankle dorsiflexion. These mechanisms are referred to as the hip–spine and knee–spine syndromes. The spine, hip, and knee are anatomically connected, and the pain and discomfort of the lower back, hip, and knee frequently arise due to degenerative changes of these structures. Thus, these mechanisms are considered as the knee–hip–spine syndrome. Spinal fusion, total hip arthroplasty, and total knee arthroplasty are the surgical procedures for severe degeneration, and their clinical outcomes for the affected sites are promising. However, despite surgeries, other structures may degenerate and result in complications, such as proximal junctional kyphosis and hip dislocation, following spinal fusion. Therefore, it is necessary to evaluate each patient under specific conditions and to treat each section while considering associations between the target structure and entire body. The purpose of this article is to introduce postural maintenance, variations with age, and improvements with surgical interventions of spine, hip, and knee as the knee–hip–spine syndrome.

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.

The modified Kostuik transilial bar technique has acceptable results in neuromuscular spinal deformity correction

The aim of this study is to evaluate the results of the modified Kostuik transilial bar technique for neuromuscular scoliosis (NS). We reviewed the records of 21 patients treated for NS with this instrumentation. There were 14 females and seven males, with an average age of 15.6 years (range: 9-21 years). We determined patients' demographics, correction ratio of both curve and pelvic obliquity, loss of correction, screw loosening at first sacral vertebra, and clinical outcomes. Mean follow-up was 56 months (range: 34-96 months). There were no reoperations, no screw breakage, and no significant loss of correction. The mean preoperative coronal Cobb angle was 71.4°±8.7°, the initial postoperative measurements had a mean Cobb angle of 19.2°±7.2°, and at the last follow-up, the mean Cobb angle was 23.6°±6.9° (P<0.001). Pelvic obliquity decreased from 27.7°±12.4° to 9.1°±5.3° at follow-up and to 11.9°±6.3° at the last follow-up (P<0.001). The preoperative pelvic obliquity angle was significantly higher at the patients with screw loosening (P=0.016). There was one established as well as one possible pseudoarthrosis in our patients. The new technique does appear to possibly become an alternative to conventional lumbosacral fixation techniques. Integration of the bar with pipe-type connector onto the long spinal instrumentation with oblique connectors can prevent the most unenviable complications such as wide exposure, hardware prominence, reoperation, and pseudoarthrosis.

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.

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.

Prediction of mechanical complications in adult spinal deformity surgery-the GAP score versus the Schwab classification

BACKGROUND CONTEXT

Surgery for adult spinal deformity is a challenging and complex procedure with high reported complication (8.4%-42%) and revision rates (9%-17.6%). Failure to achieve or maintain adequate postoperative sagittal alignment has been reported to be the main cause of mechanical complications. In order to define appropriate surgical targets, the Scoliosis Research Society-Schwab classification and the Global Alignment and Proportion (GAP) score were established. In the literature, no study has yet compared these classification systems with respect to the risk of developing mechanical complications.

PURPOSE

To assess and compare the ability of the Schwab classification and the GAP score to predict mechanical complications following adult spinal deformity surgery.

STUDY DESIGN

Two-center, retrospective cohort study.

PATIENT SAMPLE

Thirty-nine patients suffering adult spinal deformity who underwent long segment spinal fusion (≥4 levels), minimum follow-up of 2years.

OUTCOME MEASURES

The ability of the Schwab classification and GAP score to predict mechanical failure was determined by computing the Area Under the receiver operating characteristic curve.

METHODS

Full-spine pre- and postoperative radiographs of all patients were analyzed for mechanical complications. Subsequently, the pre- and postoperative Schwab and GAP score were determined. Logistic regression analysis was used to assess the ability of both systems to determine which was the most appropriate for the prediction of mechanical failure. Correlations between the various factors constituting the GAP score and Schwab classification were estimated using the Spearman rank order correlation coefficient.

RESULTS

The results demonstrated that both classification systems are capable of predicting radiographic evidence of mechanical failure; however, the GAP score proved to be significantly better (p=.003). The relative pelvic version of the GAP score serves a similar role as the pelvic tilt modifier from the Schwab classification (ρ=-0.84, p<.01). The relative lumbar lordosis from the GAP score functions much like the PI-LL modifier from the Schwab classification (ρ=-0.94, p<.01). The GAP score is most significantly dependent on relative spinopelvic alignment, relative lumbar lordosis, and relative pelvic version (ρ=0.85, ρ=0.84, and ρ=0.84, respectively, p<.01). Correlation with the lordosis distribution index was also significant but was not as strong (ρ=0.65, p<.01). Age, on the contrary, showed poor correlation with the GAP score (ρ=0.17, p=.300).

CONCLUSIONS

Both the Schwab classification and the GAP score are capable of predicting mechanical complications. The GAP score proved to be significantly more appropriate. This difference is probably attributed to the fact that in the GAP score all parameters are related to the patient's individual pelvic incidence.

Factors Predicting the Surgical Risk of Osteoporotic Vertebral Compression Fractures

The aim of our study was to investigate the association between global spinal alignment, spinopelvic parameters, and outcomes of osteoporotic vertebral compression fractures (OVCF). Patients with vertebral compression fractures seen at our hospital between October 2017 and November of 2018 with a bone mineral density (BMD) T-score < -2.5 were recruited for the study. Surgical intervention was performed after eight weeks of conservative treatment depending on clinical symptoms and the willingness of patients. Spinopelvic and sagittal alignment parameters were compared between patients who had surgery and those that did not. Seventy-nine patients were included in the study. Twenty-five patients (31.6%, mean age: 73.28 ± 9.78 years) received surgery, and 54 (68.3%, mean age: 73 ± 8.58 years) conservative treatment only. Pelvic tilt, pelvic incidence, and local kyphotic angle were statistically different between the groups (all p < 0.05). A sagittal vertical axis ≥ 50 mm, distance between the C7 plumb line and the center of the fractured vertebra (DSVA) ≥ 60 mm, pelvic incidence outside of the range of 44 to 62°), and pelvic tilt ≥ 27° were associted with the need for surgical intervention. Measurement of spinopelvic parameters can predict the need for surgery in patients with OVCF.

The third dimension of scoliosis: The forgotten axial plane

Idiopathic scoliosis is a three-dimensional (3D) deformity of the spine. In clinical practice, however, the diagnosis and treatment of scoliosis consider only two dimensions (2D) as they rely solely on postero-anterior (PA) and lateral radiographs. Thus, the projections of the deformity are evaluated in only the coronal and sagittal planes, whereas those in the axial plane are disregarded, precluding an accurate assessment of the 3D deformity. A universal dogma in engineering is that designing a 3D object requires drawing projections of the object in all three planes. Similarly, when dealing with a 3D deformity, knowledge of the abnormalities in all three planes is crucial, as each plane is as important as the other two planes. This article reviews the chronological development of axial plane imaging and spinal deformity measurement.

Impact of pelvic incidence on change in lumbo-pelvic sagittal alignment between sitting and standing positions

PURPOSE

Lumbo-pelvic sagittal alignment is affected by pelvic incidence (PI), and the PI represents the compensatory capacity of lumbo-pelvic sagittal alignment. The purpose of this study was to analyze changes in lumbo-pelvic sagittal alignment between the standing and sitting positions and to analyze its association with PI.

METHODS

This study included 253 subjects (160 men and 93 women; age 53.6 ± 7.4 years). The subjects were divided into three groups (younger age group (YG), from 20 to 49 years; middle age group, from 50 to 69 years, and older age group (OG), of 70 years and above). Lumbar lordotic angle (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), and the associations between the changes in LL (∆LL), SS (∆SS), PT (∆PT), and PI were analyzed.

RESULTS

In the YG, the amount of change in LL, SS, and PT was larger than in the OG. These parameters correlated with age in the standing position but not in the sitting position. On the other hand, in all groups, there were positive correlations between PI and changes between the standing and sitting positions. Multiple logistic regression analysis demonstrated that ∆LL = 3.81 - 0.72 × PT + 0.52 × PI, ∆SS = - 4.50 - 5.3 × PT + 0.34 × PI, and ∆PT = - 9.1 + 3.5 × PT - 0.21 × PI.

CONCLUSIONS

Change in lumbo-pelvic parameters between the sitting and standing positions correlated with PI. These slides can be retrieved under Electronic Supplementary Material.

Predicting the Effect of Bilateral Pelvic Osteotomy on Sagittal Alignment Correction and Surrounding Muscles: A Mathematical Model

Study Design. Mathematical Model. Objectives. To investigate the relationship between pelvic osteotomy opening angle (OA) and its effect on spinopelvic sagittal parameters as well as the resting length of surrounding muscles. Methods. Predictive equations correlating OA with spinopelvic parameters were derived using geometric relationships. A geometric model calculated spinopelvic parameters (SVA, pelvic incidence [PI], PT, and T1 pelvic angle [TPA]) produced by progressively increasing the OA. These values were compared to optimal balance criteria in the literature. Four muscles crossing the osteotomy site were evaluated: Gluteus Medius (GMED), Gluteus Maximus (GMAX), Piriformis (P), and Tensor Fascia Lata (TFL). Insertion points were obtained from an OpenSim software model. GMAX and GMED were subdivided into 3 (anterior, middle, and posterior). Results. OA correlated negatively with PI, TPA, and SVA and positively with PT. From baseline SVA of 22 cm, OA 21° reduced SVA to 5cm. OA 23° reduced TPA to 14°. OA 30° increased PT to 20°. OA 26° decreased PI-LL to 10°. OA range of 26°-30° resulted in optimal sagittal deformity correction. OA correlated with SR positively for TFL and anterior GMED and negatively for the rest of muscles. For this OA, the SR approximately decreased 6%, 5%, 6%, 8%, and 5% for posterior GMED, anterior GMAX, middle GMAX, posterior GMAX, and P, respectively. It increased 8% and 4% for anterior GMED and TFL, respectively. Conclusion. Predictive relationships between osteotomy OA and spinopelvic parameters were shown, providing proof of concept that sagittal balance may be achieved via pelvic osteotomy.

SURGICAL CORRECTION OF POST-TRAUMATIC KYPHOSIS WITH OSTEOTOMIES IN THE SPINE

ABSTRACT Objective: To analyze the clinical and radiological evolution, indications and complications of the types of osteotomies in patients with disturbed sagittal balance (SB) resulting from post-traumatic kyphosis. The SB can be measured with a plumb line from the center of the body of C7 to S1, which allows recognizing the misalignment. The imbalance can be corrected by osteotomy. Methods: Thirty patients with SB loss due to post-traumatic kyphosis were studied from January 2014 to December 2017. SPO, PSO and VCR were performed to evaluate the degree of kyphosis before and after surgery, the Oswestry questionnaire was applied and the degree of correction, the days of hospital stay and transoperative bleeding were assessed. Results: Age, 50 years, SD = 14, follow-up time: 2-3 years. We performed 11 (36.7%) osteotomies of S-P, 17 (56.7%) pedicle subtractions and 2 (6.6%) vertebrectomies. Most of the lesions were found between levels L1 and L2; the complications were dehiscence of the surgical wound in 4 patients (13.3%) and infection in 2 (6.6%). The minimum surgical time was 3 hours; the Oswestry questionnaire did not showed statistically significant difference during the preoperative period, however, considerable improvement was observed 2 years after surgery. Conclusions: The use of corrective vertebral osteotomies significantly re-establishes the spinopelvic balance altered by different pathologies. It allows correcting in a single surgery the sagittal balance, achieving corrections from 10° to 40°, depending on the type of osteotomy performed, being a safe and effective procedure, which allows to restore the spinopelvic balance, improving the quality of life of the patients. Level of Evidence IIb; Prospective cohort study.

Impact of Adult Scoliosis on Roussouly Sagittal Shape Classification

STUDY DESIGN

A retrospective analysis of data collected prospectively in an adult spine deformity multicenter database.

OBJECTIVE

The aim of this study was to determine the impact of adult scoliosis (AS) on the type of Roussouly sagittal shape in terms of classification applicability, scoliosis modification of a patient theoretical sagittal shape, and coronal-sagittal deformity associations.

SUMMARY OF BACKGROUND DATA

Roussouly described a four-type sagittal shape classification in healthy individuals, which has been also applied to patients with degenerative spinal disease. However, it remains uncertain if its principles can be applied to AS patients.

METHODS

AS patients recorded in a prospective multicenter database of adult spinal deformity were included. Preoperative sagittal radiographs were analyzed using the KEOPS software to measure pelvic parameters, global sagittal alignment, and the various criteria used for the Roussouly classification. The different sagittal shape types were compared using the Chi-square and McNemars tests, and analysis of variance with Bonferroni correction.

RESULTS

The classification was applicable to all of the 190 analyzed AS patients. In addition to Roussouly criteria, two parameters helped differentiate the different shapes: T10-L2 angle (24° ± 19 type-1; 14° ± 15 type-2; 3° ± 15 type-3; 0.4° ± 14 type-4; P < 0.001), and lordosis distribution index (90% ± 17 type-1; 83% ± 16 type-2; 73% ± 21 type-3; 63% ± 16 type-4; P < 0.001). AS changed the theoretical shape in 34% of the patients (P < 0.001). Curve etiology and curve pattern were not associated with any particular type of sagittal shape (P > 0.05). Type-1 was associated with older patients (P = 0.02), degenerative curves (P = 0.02), and greater PI-LL mismatch (P = 0.012). Types 3 to 4 were associated with younger age and idiopathic etiology (P < 0.001).

CONCLUSION

Roussouly four-type sagittal shape classification could be applied to AS patients. AS modified the theoretical type in one of every three patients. No particular association was found between the sagittal types and specific coronal deformities. Sagittal shape recognition in patients with AS will help restore the appropriate theoretical shape through surgery, which can eventually lead to better surgical outcomesLevel of Evidence: 2.

Loss of Pelvic Incidence Correction After Long Fusion Using Iliac Screws for Adult Spinal Deformity: Cause and Effect on Clinical Outcome

STUDY DESIGN

Retrospective observational cohort study.

OBJECTIVE

To determine change in pelvic incidence (PI) and loss of correction after long fusion with iliac screws, the effect of iliac screw loosening, and global alignment according to postoperative PI.

SUMMARY OF BACKGROUND DATA

Posterior long fixation and fusion of the thoracic to the ilium is one of the most common surgical treatments for adult spinal deformity (ASD). Long fusion to the sacrum with iliac screws decreases the PI by 3.9° after surgery. PI decreases once by long fusion with iliac screws. However, if the iliac screw loosens, PI may cause correction loss and return to the preoperative PI.

METHODS

We retrospectively reviewed the cases of 69 consecutive patients with ASD. Their mean age (SD) was 70.5 (7.3) years, 12% were male. PI was evaluated preoperatively, early- and 1-year postoperatively. We compared change in PI with and without loosening of iliac screws, spinopelvic parameters according to 1-year-postoperative PI.

RESULTS

PI decreased significantly from 51.8° (9.3°) to 48.1° (9.5°) early postoperatively (P < 0.01). PI increased significantly from 48.1° (9.5°) to 49.6° (9.7°) within a year postoperatively (P < 0.01). Significant loss of PI correction (2.3°, P < 0.01) occurred within a year after surgery in patients with iliac screw loosening and was significantly different from the PI loss in those without screw loosening (53.9°, 48.2°, P = 0.03). Pelvic tilt, sacral slope, C7 sagittal vertical axis, global tilt, and T1 pelvic angle were significantly smaller in the group with PI <50° postoperatively at 1 year compared with the group with PI >50°.

CONCLUSION

Although PI decreases after long fusion surgery with iliac screws, significant correction loss appears within a year. Loosening of iliac screws may exacerbate this loss. Patients with PI <50° postoperatively were able to maintain better global alignment.

LEVEL OF EVIDENCE

3.

Sagittal Alignment After Surgical Treatment of Adolescent Idiopathic Scoliosis-Application of the Roussouly Classification

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To investigate spinopelvic alignment and spine shape in patients surgically treated for adolescent idiopathic scoliosis (AIS) and to assess the distribution and clinical applicability of the Roussouly classification.

SUMMARY OF BACKGROUND DATA

How spinopelvic alignment is affected in AIS patients is not well established. Roussouly et al. proposed a classification based on the sagittal spinal profile and spinopelvic alignment that may have clinical utility in these patients.

METHODS

A consecutive cohort of 134 surgically treated AIS patients were included. Whole-spine standing lateral radiographs were analyzed preoperatively, one-week postoperatively and at two-year follow-up. Patients were categorized using the modified Roussouly classification and analyzed for sagittal alignment.

RESULTS

Postoperatively, global thoracic kyphosis (TK) decreased by 2.6° and lumbar lordosis (LL) decreased by 6.2°(p ≤ .012) while Pelvic tilt (PT) increased 1.4° (p = .024). At two-year follow-up, TK and LL had returned to preoperative values (p ≥ .346) while PT had decreased from preoperative 9.7 ± 7.6° to 7.0 ± 7.5° (p > .001). Proximal junctional angle increased from 8.4 ± 5.0° preoperatively to 12.8 ± 8.9 (p < .001). Preoperatively, Roussouly curve types were distributed equally apart from a lower rate of type 1 (12%). At final follow-up, 30% were categorised as type 3 with pelvic anteversion which is considerably higher than the normal adolescent population. Only three patients were type 1 at the final follow-up. Overall, we found a high rate of proximal junctional kyphosis (16%), PI-LL mismatch (60%) and pelvic anteversion (38%). In preoperative type 1 patients, the rate was 50%, 82% and 64%, respectively.

CONCLUSION

We found that immediate postoperative changes in lordosis and kyphosis were reversed at final follow-up and found evidence of proximal junctional kyphosation and pelvic anteversion as the main compensatory mechanisms. Poor sagittal alignment was frequent in type 1 curves, and surgical treatment may need to be individualized according to the sagittal profile.

LEVEL OF EVIDENCE

III.

Effect of thoracic kyphosis formation and rotational correction by direct vertebral rotation after the simultaneous double rod rotation technique for idiopathic scoliosis

OBJECTIVE

The objective of the present study was to evaluate the effect of thoracic kyphosis formation and rotational correction by direct vertebral rotation (DVR) after the simultaneous double-rod rotation technique (SDRRT) for idiopathic scoliosis (IS).

PATIENTS AND METHODS

The present study included twelve patients with IS who received SDRRT (SDRRT group) and twelve patients with IS who received DVR after SDRRT (SDRRT + DVR group). We investigated the following parameters preoperatively, postoperatively, and at postoperative 2 years: Cobb angle (PT, MT, T/L, C7-CSVL, AVT, TK (T5-12), LL(L1-S1) RSH, the angle of rotation (RAsag), percent change of RAsag and SRS22 (at postoperative 2 years only).

RESULTS

Preoperatively, the mean main thoracic curve was 58.9 ± 12.4° for the SDRRT group and 59.9 ± 16.0° for the SDRRT + DVR group, which was corrected to 14.6 ± 6.7° and 13.4 ± 4.9° postoperatively. and 14.9 ± 7.1° and 14.3 ± 4.1° at postoperative 2-year follow-up, respectively. Correction rates were 75.4 ± 10.4% and 77.2 ± 8.0 % postoperatively. Thoracic kyphosis increased postoperatively and at postoperative 2-year follow-up in both the SDRRT group and the SDRRT + DVR group. The mean preoperative TK was 11.4 ± 7.3° in the SDRRT group, and 12.8 ± 11.5° in the SDRRT + DVR group, which improved significantly to 24.8 ± 5.2° and 23.6 ± 3.5° postoperatively and 23.3 ± 3.9° and 24.2 ± 6.0° at postoperative 2-year follow-up, respectively. Correction of vertebral rotation as RAsag was significantly better in the SDRRT + DVR group than in the SDRRT group. The mean preoperative RAsag was 19.1 ± 6.7° in the SDRRT group, and 18.3 ± 7.5° in the SDRRT + DVR group, which improved to 13.3 ± 4.3° and 10.1 ± 2.9° postoperatively (P = 0.04) and 13.9 ± 4.0° and 10.6 ± 2.8° at postoperative 2-year follow-up (P = 0.02), respectively.

CONCLUSION

DVR after SDRRT for idiopathic scoliosis allowed for rotation correction without compromising kyphosis formation.

The Effect of Paravertebral Muscle on the Maintenance of Upright Posture in Patients With Adult Spinal Deformity

OBJECTIVE

We investigated the relationship between cross-sectional area (CSA) of paravertebral muscle and trunk tilt at standing and walking in adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Although the importance of back muscles for the development of spinal kyphosis was well described, the influence on maintaining the sagittal balance was unclear.

METHODS

Forty-five female patients (mean age, 68.8 years) with ASD were studied. We measured sagittal vertical axis [SVA], pelvic tilt [PT], and pelvic incidence-lumbar lordosis [PI-LL]) by lateral spine radiograph. For the assessment of trunk tilt standing-trunk tilt angle (STA) by lateral standing radiograph, gait-trunk tilt angle (GTA) by lateral gait images, and the increasing trunk tilt angle (ITA) by subtracting the STA from the GTA were calculated. Using L1/2 and L4/5 axial MRI, the CSAs of bilateral multifidus muscles (MF) and elector spinae (ES) removed fat by Image J software were calculated. We examined the correlation between trunk tilt angle (STA, GTA, and ITA) and spinopelvic parameters (SVA, PT, and PI minus LL) and also the correlation among muscle CSA, trunk tilt angle (STA, GTA, and ITA), and Oswestry Disability Index (ODI).

RESULTS

The mean STA, GTA, and ITA were 4.2°, 13.0°, and 8.8°, respectively. The CSAs of back muscles were 278 mm² at L1/2 MF, 1,687 mm² at L1/2 ES, 636 mm² at L4/5 MF, and 1,355 mm² at L4/5 ES, respectively. Trunk tilt angle had significant relations with spinopelvic parameters. Concerning about muscle CSA, significant correlations were observed between STA and L4/5 MF (r = -0.517), GTA and L1/2 ES (r = -0.461) and L4/5 MF (r = -0.476), and ITA and L1/2 ES(r = -0.429). ODI showed significant correlation with STA and GTA.

CONCLUSIONS

Paravertebral muscles were crucial to keep upright posture during walking as well as standing.

Association between visual classification of kyphosis and future ADL decline in community-dwelling elderly people: the Kurabuchi study

This cohort study conducted in Japan showed that severe age-related kyphosis was visually detected. The visual assessment of kyphosis was associated with declines in ADL, suggesting that we can easily identify people at high risk to develop future ADL reduction in the community setting.

PURPOSE

Age-related kyphosis is related with declines in activities of daily living (ADL). Its conventional diagnosis has been made by orthopedic surgeons and trained examiners using specialized equipment such as X-rays. We investigated whether visual classification of kyphosis by laypersons accurately predicted future ADL decline.

METHODS

This study was part of the Kurabuchi Study, a cohort study of community-dwelling elderly Japanese. Between 2009 and 2010, three layperson raters used reference illustrations to classify 532 participants without ADL decline at study baseline into four categories. Other examiners used conventional methods to assess kyphosis in the same participants: curve ruler, Spinal Mouse, and the block method. ADL decline was defined as the development of dependence according to the Katz Index, admission to a nursing home, or certification of long-term care need.

RESULTS

Thirty-five of the participants (6.6%) were classified with the most severe degree of kyphosis at baseline by visual assessment. Interrater agreement was high (Kappa = 0.73) for the most severe group. During 4.5 years of follow-up, 106 participants (19.9%) showed ADL decline. On the basis of visual assessment, the adjusted risk ratio for ADL decline among the participants with the most severe kyphosis was 2.6 (95% CI: 1.4-4.6). Assessments of kyphosis made with the Spinal Mouse also accurately predicted ADL decline.

CONCLUSIONS

Visual assessment of kyphosis predicted future declines in ADL in this study. Since our method requires no special tools or training, it may be useful for identifying those at high risk of ADL decline.

Correlation Between Postoperative Distribution of Lordosis and Reciprocal Progression of Thoracic Kyphosis and Occurrence of Proximal Junctional Kyphosis Following Surgery for Adult Spinal Deformity

STUDY DESIGN

This was a retrospective cohort study using consecutive patients.

OBJECTIVES

The objectives of this study were to evaluate the effect of lumbar lordosis (LL) construction on postoperative reciprocal progression of thoracic kyphosis (TK) and occurrence of proximal junctional kyphosis (PJK) following surgery for adult spinal deformity (ASD).

SUMMARY OF BACKGROUND DATA

A large postoperative TK has been reported as an iatrogenic risk factor for PJK following surgery for ASD. Therefore, knowing how to anticipate and regulate postoperative reciprocal progression in TK with LL restorative surgery is important to prevent PJK. The LL proportion including distribution of the lordosis (lordosis distribution index: LDI) in the lower (L4-S1) and upper (L1-L3) arcs has been known as important because it alters the distribution of load. However, the influence of postoperative LL construction on postoperative reciprocal change in TK resulting in PJK is largely unknown.

METHODS

Sixty-six consecutive patients with ASD treated with LL restorative surgery with a fusion level consistently selected from T8-T10 to the pelvis and followed-up for a minimum of 1 year. Abnormal PJK was evaluated according to the Boachie-Adjei classification. Roland-Morris Disability Questionnaire and Oswestry Disability Index were measured at 1 year after surgery.

RESULTS

The prevalence of PJK in the present study was 33.3%. Outcomes of patients with PJK were significantly worse than in patients without PJK, regardless of PJK grade. Postoperative reciprocal progression in TK with LL restorative surgery was found. Preoperative risk factors of PJK were older age and smaller sacral slope angle. Postoperative risk factors for PJK included increased TK and decreased LDI. We found a strong correlation between postoperative LDI and reciprocal progression of TK resulting in PJK.

CONCLUSIONS

Postoperative LDI is crucial to prevent excess reciprocal progression of TK resulting in PJK.