The global alignment in patients with lumbar spinal stenosis: our experience using the EOS full-body images

Long-term efficacy of Waveflex semi-rigid-dynamic-internal-fixation system in delaying intervertebral disc degeneration at adjacent segments and improving spinal sagittal imbalance

The Waveflex semi-rigid-dynamic-internal-fixation system shows good short-term effects in the treatment of lumbar degenerative diseases, but there are few long-term follow-up studies, especially for recovery of sagittal balance. Fifty patients with lumbar degenerative diseases treated from January 2016 to October 2017 were retrospectively analysed: 25 patients treated with Waveflex semi-rigid-dynamic-internal-fixation system (Waveflex group) and 25 patients treated with double-segment PLIF (PLIF group). Clinical efficacy was evaluated by Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI). Imaging data before surgery and at 3 months, 1 year, and 5 years postoperatively was used for imaging indicator assessment. Local disc degeneration of the cephalic adjacent segment (including disc height index (DHI), intervertebral foramen height (IFH), and range of motion (ROM)) and overall spinal motor function (including lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and |PI-LL|) were analysed. Regarding clinical efficacy, comparison of VAS and ODI scores between the Waveflex and PLIF groups showed no significant preoperative or postoperative differences. The comparison of the objective imaging indicators showed no significant differences in the DHI, IFH, LL, |PI-LL|, and SS values between the Waveflex and PLIF groups preoperatively and 3 months postoperatively (P > 0.05). These values were significantly different at 1 and 5 years postoperatively (P < 0.05), and the Waveflex group showed better ROM values than those of the PLIF group (P < 0.05). PI values were not significantly different between the groups, but PT showed a significant improvement in the Waveflex group 5 years postoperatively (P < 0.05). The Waveflex semi-rigid dynamic fixation system can effectively reduce the probability of intervertebral disc degeneration in upper adjacent segments. Simultaneously, patients in the Waveflex group showed postoperative improvements in LL, spinal sagittal imbalance, and quality of life.

An appropriate method for predicting the femoral angle on whole-body X-ray images from full-spine X-ray images

INTRODUCTION

The importance of lower-limb compensation in patients with spinal malalignment due to spinal pathologies has been emphasized. The latest whole-body X-ray images (WBX) have enabled evaluations of whole-body alignment from head to toe. However, WBX is still not commonly available. Thus, the present study aimed to examine an alternative measurement method of the femoral angle on usual full-spine X-ray images (FSX) that approximates the femoral angle on WBX.

METHODS

A total of 50 patients (age, 52.8 ± 25.3 years; female, n = 26; male, n = 24) underwent WBX and FSX. The following parameters were measured on lateral view X-rays: WBX and FSX femoral angle (angle between the femoral axis and a perpendicular line); FSX femoral distance (distance from the center of femoral head to the distal femur on FSX); WBX intersection length (length between the center of the femoral head and the intersection point [the point at which the line connecting the center of the femoral head and the midpoint of the femoral condyle intersects the center line of the femur] on WBX).

RESULTS

The WBX femoral angle, and FSX femoral angle were 0.16 ± 4.2°, and -0.53 ± 4.1°, respectively. The FSX femoral distance was 102.7 ± 41.1 mm. An ROC curve analysis revealed that the cut-off value of the FSX femoral distance associated with minimal difference in the WBX and FSX femoral angles (<3°) was 73 mm (sensitivity 83.3%, specificity 87.5%, AUC 0.80). The WBX intersection length was 105.3 ± 27.3 mm.

CONCLUSION

To calculate the femoral angle on FSX that approximates the WBX femoral angle, the femoral distance on FSX ≥73 mm is preferable. We suggest using the FSX femoral distance within the range of 80 mm-130 mm as a simple numerical value that meets all criteria.

Correcting intervertebral rotation and scoliosis simultaneously by oblique lumbar interbody fusion: a 3D analysis of EOS images

Purpose

With advancements in minimally invasive techniques, oblique lumbar interbody fusion (OLIF) has gained widespread acceptance and is now commonly performed for adult degenerative scoliosis (ADS). The objective of this research paper is to evaluate three-dimensional (3D) intervertebral motions in EOS models before and after surgery and subsequently assess the efficacy of the 3D correction achieved through staged OLIF.

Methods

In this retrospective study, 29 consecutive patients diagnosed with ADS were included, with a mean age of 63.6 years, who underwent staged OLIF surgery between 2018 and 2021. Spinopelvic parameters were assessed using EOS images, and 3D models were reconstructed to measure intervertebral motion angles (IMAs) in 70 surgical intervertebral segments, comprising wedge, lordosis, and axial rotation angles. Regression analysis was conducted to compare IMAs in different planes before and after the staged OLIF surgery.

Results

Significant three-dimensional correction was observed in 70 intervertebral segments following the first-stage OLIF. The wedge angles decreased from 5.2°± 4.2° to 2.7°± 2.4° (P < 0.001). The lordosis angles increased from 5.1°± 5.9° to 7.8°± 4.6° (P = 0.014), while the axial rotation angles decreased from 3.8°± 2.6° to 2.3°± 2.1° (P < 0.001). Linear regression analysis revealed a positive correlation between wedge angles and axial angles preoperatively (P < 0.001, r = 0.43), as well as between corrected wedge angles and corrected axial angles (P < 0.001, r = 0.42).

Conclusion

This study demonstrated that intervertebral motions had a correlation between coronal and axial planes in lumbar degenerative scoliosis. First-stage OLIF was efficient at correcting segmental scoliosis by inserting cages while correcting rotation deformity simultaneously, as well as improving the sagittal spinopelvic parameters.

The age-specific normative values of standing whole-body sagittal alignment parameters in healthy adults: based on international multicenter data

PURPOSE

To investigate the age-specific normative values of whole-body sagittal alignment (WBSA) including global balance parameters in healthy adults and to clarify the correlations among parameters based on the data from three international multicenter.

METHODS

Three hundred and seventeen healthy subjects (range: 20-84 y.o., mean: 43.8 ± 14.7 y.o.) were included and underwent whole-body biplanar X-ray imaging system. Spinopelvic parameters and knee flexion (KF), the center of acoustic meatus (CAM)-hip axis (HA), and C2 dentiform apophyse (OD)-HA, the cranial center (Cr)-HA were evaluated radiologically. Sub-analysis for correlation analysis between age and parameters and among parameters was performed to investigate age-specific change and compensatory mechanisms.

RESULTS

For age-related change, C2-7 angle (r = .326 for male/.355 for female), KF (r = .427/.429), and SVA (r = .234/.507) increased with age in both male and female group. For global parameters related to the center of the gravity, correlations with age were not significant (r = .120/.161 for OD-HA, r = .163/.275 for Cr-HA, r = .149/.262 for CAM-HA). Knee flexion (KF) has correlation with global parameters (i.e., SVA, OD-HA, Cr-HA, CAM-HA) and does not have correlations with local spinopelvic alignment.

CONCLUSION

While several local alignment changes with age were found, changes in global parameters related to the center of gravity were kept relatively mild by the chain of compensation mechanisms including the lower limbs. We showed the normative values for a comprehensive WBSA in standing posture from large international healthy subjects' database.

Reciprocal Changes in the Whole-Body Following Realignment Surgery in Adult Spinal Deformity

The idea of the global balance of spine stems from Jean Dubousset, who first introduced the concept of cone of economy. Through the compensatory mechanisms, the human body maintains an upright posture and horizontal gaze in the setting of the spinal malalignment. Compensation takes place not only in the mobile spine segments, but also in the pelvis and lower extremities. Patients with a malalignment exhibit compensatory changes in the cervical hyper-lordosis, posterior pelvic shift, knee/ankle flexion, hip extension, and the pelvic retroversion. The advent of whole-body stereo radiography has yielded an improved understanding of global changes among the patients. Deformity-induced compensatory changes in the sagittal alignment could be resolved reciprocally after the surgical correction of the malalignment. Thoracolumbar realignment surgery restores the pathologic compensatory changes in the unfused spinal segments, pelvis, and the lower extremities. Similarly, reciprocal changes in the thoracolumbar spine may harmonize global sagittal alignment after the cervical reconstruction. This study reviews the compensatory mechanisms and reciprocal changes in global sagittal alignment caused by the surgical correction and highlights, the factors that should be considered while assessing a patient's compensatory status.

Relationships between Paraspinal Muscle and Spinopelvic Sagittal Balance in Patients with Lumbar Spinal Stenosis

OBJECTIVE

To investigate the relationships between measurements of paraspinal muscle and spinopelvic sagittal parameters and the predictive value of lumbar indentation value (LIV) on sagittal balance in patients with lumbar spinal stenosis.

METHODS

It was a retrospective study. We collected the data of 110 patients, who were diagnosed as lumbar spinal stenosis from December 2018 to May 2019. The total cross-sectional area (tCSA), functional cross-sectional area (fCSA), and fatty infiltration (FI) of paraspinal muscle were measured. The spinopelvic sagittal parameters were also measured, including sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and PI minus LL (PI-LL). Correlations between measurements of paraspinal muscle and sagittal parameters were investigated by Pearson correlation analysis. The multiple linear regression analysis was used to investigate the LIV, age, gender, and BMI for assessing spinopelvic sagittal balance. Receiver-operating characteristic (ROC) curve was used to find out the most optimum cut-off point of LIV for evaluating SVA.

RESULTS

There were 42 males and 68 females in this study and the mean age was 59.9 ± 10.9 years old. By Pearson correlation analysis, MF tCSA showed significant association with LL (r = 0.455, P < 0.01) and PI-LL (r = -0.286, P < 0.01). MF fCSA had a significant correlation with LL (r = 0.326, P < 0.01) and PI-LL (r = -0.209, P < 0.05). LIV was also significantly correlated to spinopelvic sagittal parameters, including SVA (r = -0.226, P < 0.05), LL (r = 0.576, P < 0.01), TK (r = 0.305, P < 0.01), and PI-LL (r = -0.379, P < 0.01). By multiple linear regression analysis, LIV was independently associated with sagittal parameters, including PI-LL and SVA. The cut-off value of LIV for SVA ≤ 50 mm was 10.5 mm (AUC = 0.641). According to the best cut-off value, patients were divided into two groups. For patients with LIV ≤ 10.5 mm, the percentage of SVA ≤ 50 mm was 54.5% (18/33), while it was 83.1% (64/77) for patients with LIV >10.5 mm.

CONCLUSIONS

As a new index to evaluate paraspinal muscle atrophy, the LIV was independently correlated to spinopelvic sagittal balance. Degeneration of paraspinal muscle was associated with spinopelvic sagittal balance.

How much change in pelvic sagittal tilt can result in hip dislocation due to prosthetic impingement? A computer simulation study

Developing spinal pathologies and spinal fusion after total hip arthroplasty (THA) can result in increased pelvic retroversion (e.g., flat back deformity) or increased anterior pelvic tilt (caused by spinal stenosis, spinal fusion or other pathologies) while bending forward. This change in sagittal pelvic tilt (SPT) can result in prosthetic impingement and dislocation. Our aim was to determine the magnitude of SPT change that could lead to prosthetic impingement. We hypothesized that the magnitude of SPT change that could lead to THA dislocation is less than 10° and it varies for different hip motions. Hip motion was simulated in standing, sitting, sit-to-stand, bending forward, squatting and pivoting in Matlab software. The implant orientations and SPT angle were modified by 1° increments. The risk of prosthetic impingement in pivoting caused by increased pelvic retroversion (reciever operating characteristic [ROC] threshold as low as 1-3°) is higher than the risk of prosthetic impingement with increased pelvic anteversion (ROC threshold as low as 16-18°). Larger femoral heads decrease the risk of prosthetic impingement (odds ratio {OR}: 0.08 [932 mm head]; OR: 0.01 [36 mm head]; OR: 0.002 [40 mm head]). Femoral stems with a higher neck-shaft angle decrease the prosthetic impingement due to SPT change in motions requiring hip flexion (OR: 1.16 [132° stem]; OR: 4.94 [135° stem]). Our results show that overall, the risk of prosthetic impingement due to SPT change is low. In particular, this risk is very low when a larger diameter head is used and femoral offset and length are recreated to prevent bone on bone impingement.

Relationships between the changes in flexion contracture and standing flexion angle of the knee and sagittal spinal alignment after total knee arthroplasty

BACKGROUND

The sagittal spinal alignment interacts with the lower extremity in patients with combined degenerative disease of the spine and lower extremity. This study aimed to clarify the relationships between the reciprocal changes in sagittal alignment of the knee, pelvis, and spine after total knee arthroplasty (TKA) in osteoarthritis patients.

METHODS

Prospectively, 36 patients who underwent primary TKA for severe knee osteoarthritis were enrolled. Their clinical and radiological evaluation included assessments of the knee flexion contracture (KFC) and standing knee flexion angle (KFA), as well as spinopelvic parameters and the global sagittal spinal alignment from standing whole-lower-extremity and whole-spine radiographs preoperatively and at postoperative 2 weeks, 6 weeks, 6 months, 1 year, and 2 years. Linear mixed models were used to assess the relationships between KFC/KFA and between spinopelvic/global sagittal spinal alignments.

RESULTS

The KFC decreased abruptly immediately after TKA, and the correction was maintained for 2 years postoperatively. The KFA decreased gradually and approached the value of the KFC after 2 years. Of the spinopelvic parameters, sacral slope and pelvic incidence decreased significantly, in ways related to changes in KFA. There was no significant relationship between sagittal spinal alignment and postoperative changes in KFC.

CONCLUSION

Although the flexion contracture was corrected immediately after TKA, the standing KFA improved gradually over 2 years. The pelvic parameters showed compensatory changes according to the KFA. The decompensated sagittal spinal malalignment was not related to a relapse in flexion contracture.

[Battle: Indication for surgery in hip-spine syndrome-Hip or spine first? : The spine surgeon's view]

Pathologies of the hip, spine and the lower extremity are often concomitant due to their three-dimensional anatomic and physiological interrelation. The real challenge lies in defining which of the pathologies is most relevant for the patient in terms of clinical symptoms and which organ should be treated first. The purpose of this review article is two-fold: Firstly, to explain the treatment dilemma of hip-spine syndrome to the treating physician. Secondly, to highlight the significance of spinal pathology in this context.

Sagittal Spinopelvic Translation Is Combined With Pelvic Tilt During the Standing to Sitting Position: Pelvic Incidence Is a Key Factor in Patients Who Underwent THA

Background

Sagittal spinopelvic translation (SSPT) is the horizontal distance from the hip center to the C7 plumb line (C7PL). SSPT is an important variable showing the overall patient balance in different functional positions which could affect the rate of hip instability. This study investigates the SSPT modification in patients who underwent total hip arthroplasty (THA).

Methods

A total of 120 patients were assessed preoperatively and postoperatively on standing and sitting acquisitions (primary unilateral THA without complication). SSPT is zero when the C7PL goes through the center of the femoral heads and positive when the C7PL is posterior to the hips’ center (negative if anterior). Three subgroups were defined based on the pelvic incidence (PI): low PI <45°, 45°< normal PI <65°, or high PI >65°.

Results

The overall mean preoperative SSPT change from standing to sitting was 2.2 cm ([-7.2 to 17.4]) (P < .05). The overall mean postoperative SSPT change from standing to sitting was 1.2 cm ([-14.2 to 22.4]) (P < .05). In low- and normal-PI groups, standing to sitting SSPT and preoperative to postoperative changes in standing SSPT were increased significantly after surgery with the C7PL behind the hips’ center (P < .05). In the high-PI group, standing to sitting SSPT was increased postoperatively (P = .034) (no significant changes from preoperative to postoperative status in standing and sitting).

Conclusions

Adaptation from standing to sitting positions combines pelvic tilt and anteroposterior pelvic translation. THA implantation induces significant changes in SSPT mainly for low- and standard-PI patients. This is an important variable to consider when investigating the causes of THA subluxation or dislocation.

EOS® imaging: Concept and current applications in spinal disorders

EOS® imaging is a proprietary imaging technology that was launched in 2007. Based on a gaseous particle detector with a multi-wire proportional chamber, it offers several advantages over other imaging modalities: low dose of radiation, ability to create 3D reconstructions, ability to conduct whole body imaging, high reproducibility in measuring various parameters of alignment and faster imaging time. EOS® imaging is slowly gaining widespread acceptance as its applications in various disorders continue to evolve. It has been found to be particularly useful and has opened up new avenues of research in the field of spinal deformities. This narrative review seeks to provide an overview of the proprietary technology behind EOS® imaging, compare it to existing imaging modalities, summarize its current applications in various spinal disorders and outline its limitations.

Clinical and radiological features of lumbar degenerative spondylolisthesis who complicates osteoarthritis of the knee

BACKGROUND DATA

Correlation between lumbar degenerative disease and degenerative disorders of the knee joint have often been reported, however, detailed research concerning lumbar degenerative spondylolisthesis (DS) who complicates osteoarthritis of the knee (KOA) are scarce.

METHODS

A total of 184 consecutive surgically treated DS patients were identified, and divided into two groups: DS patients who complicate KOA (KOA group) and DS patients without KOA (non-KOA group). DS was defined as grade 1 or more, according to Meyerding's classification, and KOA was defined as grade 3 or more according to Kellgren-Lawrence classification. Clinical and the radiological differences of DS patients between KOA group and non-KOA group were investigated in order to clarify the features of DS patients who complicate KOA. Statistical significance using student's t-test and multivariate logistic regression analysis was performed to identify independent predictors of complicating KOA in DS.

RESULTS

KOA group and non-KOA group consisted of 57 and 127 patients, respectively, with both group predominantly of female patients. Clinical features of KOA group were significantly high in age and body mass index (BMI), and more likely to complicate circulatory system disorders than non-KOA group. Radiological features of KOA group were significantly high in frequency of double adjacent level spondylolisthesis, Pelvic incidence (PI), Pelvic tilt (PT), and PI-LL. Multivariate logistic regression analysis identified coexistence of circulatory system disorders (OR 2.251, p = 0.024) and PI-LL (OR 1.04, p < 0.001) to be an independent predictors of complicating KOA in DS patients.

CONCLUSIONS

Older age and overweighted female patients coexistence of circulatory system disorders, containing double adjacent level spondylolisthesis with high PI, PT, and PI-LL were the characteristics of DS patients who complicate KOA, particularly coexistence of circulatory system disorders and significantly high lumbo-pelvic sagittal mismatch were the most significant factors above all.

The impact of surgical reduction of high-grade lumbosacral spondylolisthesis on proximal femoral angle and quality of life

BACKGOUND CONTEXT

Abnormal proximal femoral angle (PFA) was recently found to be associated with deteriorating sagittal balance and quality of life (QoL) in high-grade spondylolisthesis (HGS). However, the influence of PFA on the QoL of patients undergoing surgery remains unknown.

PURPOSE

This study compares the pre- and postoperative measurements of sagittal balance including PFA in patients with lumbosacral HGS after surgery. It also determines if PFA is a radiographic parameter that is associated with QoL in patients undergoing surgery.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Thirty-three patients (mean age 15.6 ± 3.0 years) operated for L5-S1 HGS between July 2002 and April 2015. Thirteen had in situ fusion and 20 had reduction to a low-grade slip.

OUTCOME MEASURES

The outcome measures included PFA and QoL scores measured from the Scoliosis Research Society SRS-30 QoL questionnaire.

METHODS

The minimum follow-up was 2 years. PFA and QoL were compared pre- and postoperatively. Statistical analysis used nonparametric Mann-Whitney and Wilcoxon Signed Rank tests, Chi-square tests to compare proportions, and bivariate correlations with Spearman's coefficients.

RESULTS

A decreasing PFA correlated with less pain (r = -0.56, p = .010), improved function (r = -0.51, p = .022) and better self-image (r = -0.46, p = .044) postreduction. Reduction decreased PFA by 5.1° (p = .002), whereas in situ fusion did not alter PFA significantly. Patients with normal preoperative PFA had similar postoperative QoL regardless of the type of surgery, except for self-image, which improved further with reduction (3.73 ± 0.49 to 4.26 ± 0.58, p = .015). Patients with abnormal preoperative PFA tended to have a higher QoL in all domains after reduction.

CONCLUSION

Decreasing PFA correlates with less pain, better function and self-image. Reduction of HGS decreases PFA. Reduction also relates to a better postoperative QoL when the preoperative PFA is abnormal. When the preoperative PFA is normal, in situ fusion is equivalent to reduction except for self-image, which is better improved after reduction.