Radiographical spinopelvic parameters and disability in the setting of adult spinal deformity: a prospective multicenter analysis

Impact of Patient-specific Factors and Spinopelvic Alignment on the Development of Adjacent Segment Degeneration After Short-segment Lumbar Fusion

STUDY DESIGN

Prospective cross-sectional cohort study.

OBJECTIVES

The main purpose of this study was to evaluate the association between demographical, surgery-related and morphologic parameters, and the development or progress of adjacent segment degeneration (ASD) after short-segment lumbar fusions.

SUMMARY OF BACKGROUND DATA

ASD is a major long-term complication after lumbar fusions. Possible risk factors are related to the patients' demographics, spinopelvic anatomy, or preoperative lumbar intervertebral disk conditions, but the role of these parameters is still not clear.

METHODS

A prospective cross-sectional study of 100 patients who underwent 1- or 2-level open lumbar transforaminal interbody fusions due to a lumbar degenerative pathology was conducted. Demographical, radiologic findings, and magnetic resonance imaging features were analyzed to identify factors associated with ASD in 5-year follow-up.

RESULTS

ASD patients showed higher level of pain ( P =0.004) and disability ( P =0.020) at follow-up. In univariate analysis, older age ( P =0.007), upper-level lumbar fusion ( P =0.007), lower L4-S1 lordosis ( P =0.039), pelvic incidence-lumbar lordosis mismatch ( P =0.021), Pfirrmann grade III or higher disk degeneration ( P =0.002), and the presence of disk bulge/protrusion ( P =0.007) were associated with ASD. In multivariate analysis, the presence of major degenerative sign (disk degeneration and/or disk bulge) was the significant predictor for developing ASD (odds ratio: 3.85, P =0.006).

CONCLUSION

By examining the role of different patient- and procedure-specific factors, we found that preoperative major degenerative signs at the adjacent segment increase the risk of ASD causing significantly worse outcome after short-segment lumbar fusion. On the basis of our results, adjacent disk conditions should be considered carefully during surgical planning.

The Impact of Spinopelvic Parameters on Hip Degeneration After Spinal Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

This study aimed to investigate the effects of spinopelvic alignment parameters after spinal fusion on the rate of joint space narrowing in nonarthritic hips.

SUMMARY OF BACKGROUND DATA

Spinal fusion affects the forces on the adjacent hip joint. Therefore, hip joint narrowing may be increased after spinal fusion surgery. However, the relationship between spinal alignment and hip degeneration remains unclarified.

METHODS

We retrospectively reviewed data from patients who underwent lumbar spinal fusion from 2011 to 2018 at our institute. Patients with hip osteoarthritis (Kellgren-Lawrence grade ≥II) or hip dysplasia were excluded. The rate of hip joint space narrowing after spinal fusion was measured in 191 patients (382 hips). We assessed the effects of the following spinopelvic alignment parameters on the joint narrowing rate: pelvic tilt, sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL, sagittal vertical axis, and distance between the C7 plumb line, and the central sacral vertical line (C7-CSVL).

RESULTS

The hip joint narrowing rate was greater when four or more levels were fused compared with single-level fusion. After adjusting for the effects of patient-related factors, the alignment parameters significantly associated with the hip joint narrowing rate were the PI ( P = 0.0002), SS ( P = 0.047), and PI-LL ( P = 0.0022). A subgroup analysis of patients who underwent long fusion (four or more levels combined with iliac screws) also indicated that the PI ( P = 0.013), SS ( P = 0.0054), and PI-LL ( P = 0.046) were associated with the hip joint narrowing rate.

CONCLUSION

The PI, SS, and PI-LL were associated with the progression of hip joint narrowing after spinal fusion, especially after fusion of four or more levels. Surgeons need to be aware of the risk of increased hip joint narrowing in patients with a large PI, SS, and PI-LL after fusion surgery.

Association between sagittal spinal alignment and mechanical complications after primary total hip arthroplasty: a systematic review

Objective

Total hip arthroplasty (THA) affects pelvic posture and spinal alignment. These postural changes may further predispose patients to mechanical complications (MCs) after THA. The aim of this study was to conduct a systematic review to investigate whether any high-quality studies have assessed the association between sagittal spinal alignment and MCs after primary THA.

Methods

Inclusion criteria for studies were adult patients (age ≥18 years), primary THA, pre- and postoperative spinopelvic standing sagittal radiographs acquired preoperatively and at a minimum of 6-month follow-up, measurements of spinopelvic parameters, and reporting of possible MCs after THA. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Results

Six articles met the inclusion criteria. Although several studies confirmed the importance of spinal alignment when planning THA, these mainly investigated pelvic mobility as a risk factor for THA dislocation. Radiological follow-up imaging practices varied, and studies focused on different individual spinopelvic parameters.

Conclusion

Based on our study findings, no conclusions can be drawn regarding the association between sagittal spinal alignment and MCs after primary THA. Further research is needed to improve our knowledge of the connection between MCs after THA and sagittal spinal alignment.

The impact of interbody approach and lumbar level on segmental, adjacent, and sagittal alignment in degenerative lumbar pathology: a radiographic analysis six months following surgery

BACKGROUND CONTEXT

Interbody fusion, including: transforaminal (TLIF), posterior (PLIF), anterior (ALIF), and lateral (LLIF); effectively treat lumbar degenerative pathology and provide spinopelvic balance. Although the decision on surgical approach and technique are multifactorial and patient specific, the impact of the interbody approach on segmental and adjacent level lordosis could be an important factor to consider during pre-operative planning to achieve pre-specified alignment goals.

PURPOSE

The purpose of this study is to compare the 6-month postoperative radiographic outcomes in the lumbar spine following 1 to 2 level transforaminal (TLIF), posterior (PLIF), anterior (ALIF), and lateral (LLIF) interbody fusions at the L3-4, L4-5, and L5-S1 levels. As our primary outcome, we evaluated the change in segmental lordosis at the level of fusion in ALIF/LLIF approaches compared to TLIF/PLIF. Secondarily, we evaluated the pelvic incidence to lumbar lordosis (PI-LL) mismatch and examined the compensatory lordotic changes at the adjacent levels 6 months following surgery.

STUDY DESIGN

Retrospective cohort.

PATIENT SAMPLE

This retrospective study included 18 centers of various practice settings across the United States. Patients were included in the study if they underwent a one- or two-level primary lumbar fusion for degenerative pathology.

OUTCOMES MEASURES

Measurements of the pre-operative and 6-month post-operative lumbar AP and lateral lumbar plain radiographs included: pelvic incidence (PI), pelvic tilt, lumbar lordosis from L1-S1 (LL), as well as segmental lordosis (SL) of each segment between L1-S1.

METHODS

Due to there being 2 evaluated time points, patients were then grouped based on alignment into categories of preserved, restored, not corrected, and worsened.

RESULTS

474 patients underwent 608 levels of fusion. ALIF/LLIF resulted in significantly more segmental lordosis compared to TLIF/PLIF procedures at both L4-5 and L5-S1 (p<.001). Overall, ALIF/LLIF resulted in significantly more global lumbar lordotic alignment change compared to TLIF/PLIF (p=.01). Whether patients' alignment was preserved versus worsened was not significantly predicted by type of procedure. Similarly, whether patients' alignment was restored versus not corrected was not significantly predicted by type of procedure. Finally, anterior approaches resulted in decreased lordosis at adjacent levels, thus resulting in a more neutral position.

CONCLUSION

In this large multicenter retrospective study of 1 to 2 level interbody fusion surgeries, we identified that A/LLIF procedures at L4-L5 and L5-S1 resulted in greater segmental lordosis restoration and PI-LL mismatch improvement compared to T/PLIF procedures. A/LLIF may also significantly reduce lordosis (compared to T/PLIF) at the adjacent levels in a fashion that serves to reduce the lumbar lordosis that may have been increased at the fused level.

Global Spinal Realignment After Osteotomized Debridement in Active Lumbar Spinal Tuberculosis: Correlation with Patient-Reported Outcomes

OBJECTIVE

Osteotomized debridement (OD) has been proved to be highly effective in treating active thoracolumbar tuberculosis (TB); however, no research has investigated how OD affects spinal alignment. The goal of this study was to explore the global alignment compensatory mechanism after lumbar OD, as well as the correlation between spinopelvic parameters and patient-reported outcomes (PROs).

METHODS

Sixty-two patients with active lumbar spinal TB who underwent OD surgery were included. Spinopelvic parameters (C2-7 Cobb angle [C2-7 CA], sagittal vertical axis [SVA], proximal thoracic kyphosis, thoracic kyphosis, lumbar lordosis [LL], sacral slope [SS], pelvic tilt [PT], pelvic incidence [PI], spinosacral angle, and PI minus LL [PI-LL]) and PROs (Oswestry Disability Index [ODI] and Visual Analog Scale [VAS] score) were reviewed. The correlation between spinopelvic realignment and improved PROs was evaluated.

RESULTS

Compared with preoperative measurements, C2-7 CA, proximal thoracic kyphosis, thoracic kyphosis, LL, SS, and spinosacral angle significantly increased after OD, whereas SVA, PT, and PI-LL significantly decreased. ODI and VAS score significantly improved postoperatively. The improvement of VAS was observed to be correlated with variations of C2-7 CA, SVA, LL, and PI-LL. The improvement of ODI was found to be correlated with variations of SVA, LL, and PI-LL. The multiple stepwise regression analysis showed that LL was an independent predictor for ODI and VAS score.

CONCLUSIONS

The whole spine and pelvis are involved in realignment after lumbar spinal OD, which is closely related to PROs. More attention should be drawn to restoring an appropriate LL in lumbar TB surgery.

Risk Factors for Proximal Junctional Kyphosis in Fusions from the Sacrum to L1 or L2 for Adult Spinal Deformity

Introduction

Several targets have been proposed to achieve satisfactory alignment and favorable outcomes in adult spinal deformity surgery. Stopping the upper instrumented vertebra (UIV) at the thoracolumbar junction levels, especially between T11 and L1, is considered a high-risk factor for the development of proximal junctional kyphosis (PJK). Nevertheless, it is unknown in which patients the results of surgery are satisfactory when L1 or L2 is set as UIV with lumbosacral fixation. This study aimed to identify the risk factors for PJK in patients with lumbosacral fixation with L1 or L2 as UIV.

Methods

From January 2011 to December 2019, 21 consecutive patients who underwent lumbopelvic fixation for adult spinal deformity were included. The patients were divided into two groups: the PJK group (n=7) and the nonPJK group (n=14). Patients who experienced PJK within half a year of surgery were included in the PJK group. Pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), thoracic kyphosis (TK), thoracic compensation (TK compensation), sagittal vertical axis (SVA), T10-L2 angle, and T1 pelvic angle (TPA) were measured before and after surgery.

Results

No difference was found between the two groups in terms of age and sex at the time of surgery. The indices that were significantly different between the two groups were preoperative PT, PI minus LL, TK, TPA, TK compensation, and postoperative T10-L2 angle. No significant differences were found in postoperative LL, PI minus LL, PT, TK, TPA, or SVA.

Conclusions

Preoperative X-ray indices, including preoperative TPA, TK compensation, TK, PT, and PI-LL, determined the risk of PJK in fusions from the sacrum to L1 or L2. Appropriate patient selection is crucial for the success of this surgery.

Brace Prescription for Adult Scoliosis - Literature Review

Purpose:

The 2021 SOSORT guidelines stipulated that braces be prescribed for adult scoliosis with chronic pain and progressive curve. Yet, there have been no objective protocols relating to the prescription of the brace. Therefore, this review investigates if there are any objective criteria or generally agreed on protocols for brace prescription in adult scoliosis patients.

Methods:

Relevant papers were searched in PUBMED. Only articles that are in English and cover the clinical aspect of adult scoliosis bracing are included.

Results:

A total of twelve papers were identified. They include different adult scoliosis braces, ranging from elastic belts to rigid braces. The treatment protocol varied tremendously. No objective criteria were found concerning the prescription of a brace, daily wearing time, duration of the intervention, and weaning protocol. The brace treatment was primarily employed to manage low back pain.

Conclusion:

Our search showed no objective criteria and clear indications for bracing and no consensus concerning the prescription of braces, daily wearing time, and duration of the intervention for patients with adult scoliosis.

The authors proposed prescription of a brace be based on more objective radiological criteria and severity of low back pain. Brace prescription should depend on the flexibility of the curve and can range from accommodative to rigid braces of corrective design. “Corrective” brace has to be worn at least 14 hours daily for six months or until the low back pain subsides to the extent that permits daily activities with minimal discomfort. “Accommodative” brace can be worn when required.

A fresh look at spinal alignment and deformities: Automated analysis of a large database of 9832 biplanar radiographs

We developed and used a deep learning tool to process biplanar radiographs of 9,832 non-surgical patients suffering from spinal deformities, with the aim of reporting the statistical distribution of radiological parameters describing the spinal shape and the correlations and interdependencies between them. An existing tool able to automatically perform a three-dimensional reconstruction of the thoracolumbar spine has been improved and used to analyze a large set of biplanar radiographs of the trunk. For all patients, the following parameters were calculated: spinopelvic parameters; lumbar lordosis; mismatch between pelvic incidence and lumbar lordosis; thoracic kyphosis; maximal coronal Cobb angle; sagittal vertical axis; T1-pelvic angle; maximal vertebral rotation in the transverse plane. The radiological parameters describing the sagittal alignment were found to be highly interrelated with each other, as well as dependent on age, while sex had relatively minor but statistically significant importance. Lumbar lordosis was associated with thoracic kyphosis, pelvic incidence and sagittal vertical axis. The pelvic incidence-lumbar lordosis mismatch was found to be dependent on the pelvic incidence and on age. Scoliosis had a distinct association with the sagittal alignment in adolescent and adult subjects. The deep learning-based tool allowed for the analysis of a large imaging database which would not be reasonably feasible if performed by human operators. The large set of results will be valuable to trigger new research questions in the field of spinal deformities, as well as to challenge the current knowledge.

The Sagittal Plane in Spinal Fusion for Adolescent Idiopathic Scoliosis

Sagittal balance is widely recognized as the primary determinant of optimal outcomes in adult spinal deformity. In adolescent idiopathic scoliosis (AIS), coronal correction risks being obtained at the expense of sagittal malalignment after posterior spinal fusion. Apical lordosis, often underestimated on two-dimensional imaging, is the primary deforming factor in AIS. Failure to restore thoracic kyphosis and lumbar lordosis during posterior spinal fusion contributes to problematic early surgical complications, including proximal or distal junctional kyphosis and failure. Although adolescent patients often compensate for sagittal imbalance in the short-term and mid-term, late sequelae of iatrogenic sagittal imbalance include flatback syndrome, disk degeneration, cervical kyphosis, and late decompensation. Objective criteria using spinopelvic parameters and preoperative three-dimensional planning can guide sagittal plane correction during PSF for AIS. Technical caveats can help avoid sagittal plane complications, including instrumentation level selection, anchor type, and anatomic protection of adjacent levels. Other surgical techniques to optimize restoration of thoracic kyphosis include higher implant density, stiffer rod material, Ponte osteotomies, and deformity correction technique.

Change in sagittal alignment after decompression alone in patients with lumbar spinal stenosis without significant deformity: a prospective cohort study

OBJECTIVE

The authors' objective was to investigate whether sagittal balance improves in patients with spinal stenosis after decompression alone.

METHODS

This prospective longitudinal cohort study compared preoperative and 6-month postoperative 36-inch full-length radiographs in patients aged older than 60 years. Patients underwent decompression alone for central lumbar spinal stenosis with either a minimally invasive bilateral laminotomy for central decompression, unilateral laminectomy as an over-the-top procedure for bilateral decompression, or traditional wide laminectomy with removal of the spinous processes on both sides. The following radiographic parameters were measured: sagittal vertical axis (SVA), lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), PI-LL mismatch, coronal Cobb angle, and sacral slope (SS). Patient-reported outcome measures (PROMs) were collected, including scores on the Oswestry Disability Index (ODI), visual analog scale (VAS) for leg and back pain, and EQ-5D.

RESULTS

Forty-five patients (24 males) with a mean ± SD age of 71.8 ± 5.6 years were included. Sagittal balance showed statistically significant improvement, with the mean SVA decreasing from 52.3 mm preoperatively to 33.9 mm postoperatively (p = 0.0001). The authors found an increase in LL, from mean -41.5° preoperatively to -43.9° postoperatively, but this was not statistically significant (p = 0.055). A statistically significant decrease in PI-LL mismatch from mean 8.4° preoperatively to 5.8° postoperatively was found (p = 0.002). All PROM scores showed significant improvement after spinal decompression surgery. The correlations between SVA and all PROMs were statistically significant at both preoperative and postoperative time points, although most correlations were weak except for those between preoperative SVA and ODI (r = 0.55) and between SVA and VAS for leg pain (r = 0.58).

CONCLUSIONS

Sagittal balance and PROMs show improvement at short-term follow-up evaluations in patients who have undergone decompression alone for lumbar spinal stenosis.

Evaluation of Sagittal Spinopelvic Balance in Spinal Cord Stimulator Patients

OBJECTIVE

Spinal cord stimulation (SCS) has become a popular nonopioid pain intervention. However, the treatment failure rate for SCS remains significantly high and many of these patients have poor sagittal spinopelvic balance, which has been found to correlate with increased pain and decreased quality of life. The purpose of this study was to determine if poor sagittal alignment is correlated with SCS treatment failure.

MATERIALS AND METHODS

Comparative retrospective analysis was performed between two cohorts of patients who had undergone SCS placement, those who had either subsequent removal of their SCS system (representing a treatment failure cohort) and those that underwent generator replacement (representing a successful treatment cohort). The electronic medical record was used to collect demographic and surgical characteristics, which included radiographic measurements of lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). Also included were data on pain medication usage including opioid and nonopioid therapies.

RESULTS

Eighty-one patients met inclusion criteria, 31 had complete removal, and 50 had generator replacements. Measurement of sagittal balance parameters demonstrated that many patients had poor alignment, with 34 outside normal range for LL (10 vs 24 in removal and replacement cohorts, respectively), 30 for PI (12 [38.7%] vs 18 [36.0%]), 46 for PT (18 [58.1%] vs 28 [56.0%]), 38 for SS (18 [58.1%] vs 20 [40.0%]), and 39 for PI-LL mismatch (14 [45.2%] vs 25 [50.0%]). There were no significant differences in sagittal alignment parameters between the two cohorts.

CONCLUSIONS

This retrospective cohort analysis of SCS patients did not demonstrate any relationship between poor sagittal alignment and failure of SCS therapy. Further studies of larger databases should be performed to determine how many patients ultimately go on to have additional structural spinal surgery after failure of SCS and whether or not those patients go on to have positive outcomes.

Defining "Normal" Static and Dynamic Spinopelvic Characteristics: A Cross-Sectional Study

Spinopelvic characteristics influence the hip's biomechanical behavior. However, there is currently little knowledge regarding what "normal" characteristics are. This study aimed to determine how static and dynamic spinopelvic characteristics change with age, sex, and body mass index (BMI) among well-functioning volunteers.

Methods

This was a cross-sectional cohort study of 112 asymptomatic volunteers (age, 47.4 ± 17.7 years; 50.0% female; BMI, 27.3 ± 4.9 kg/m2). All participants underwent lateral spinopelvic radiography in the standing and deep-seated positions to determine maximum hip and lumbar flexion. Lumbar flexion (change in lumbar lordosis, ∆LL), hip flexion (change in pelvic-femoral angle, ∆PFA), and pelvic movement (change in pelvic tilt, ΔPT) were determined. The hip user index, which quantifies the relative contribution of the hip to overall sagittal movement, was calculated as (∆PFA/[∆PFA + ∆LL]) × 100%.

Results

There were decreases of 4.5° (9%) per decade of age in lumbar flexion (rho, -0.576; p < 0.001) and 3.6° (4%) per decade in hip flexion (rho, -0.365; p < 0.001). ∆LL could be predicted by younger age, low standing PFA, and high standing LL. Standing spinopelvic characteristics were similar between sexes. There was a trend toward men having less hip flexion (90.3° ± 16.4° versus 96.4° ± 18.1°; p = 0.065) and a lower hip user index (62.9% ± 8.2% versus 66.7% ± 8.3%; p = 0.015). BMI weakly correlated with ∆LL (rho, -0.307; p = 0.011) and ∆PFA (rho, -0.253; p = 0.039).

Conclusions

Spinopelvic characteristics were found to be age, sex, and BMI-dependent. The changes in the lumbar spine during aging (loss of lumbar lordosis and flexion) were greater than the changes in the hip, and as a result, the hip's relative contribution to overall sagittal movement increased. Men had a greater change in posterior pelvic tilt when moving from a standing to a deep-seated position in comparison with women, secondary to less hip flexion. The influence of BMI on spinopelvic parameters was low.

A radiographic and physical analysis of factors affecting seat belt position in sitting car seat

The characteristic subcutaneous hemorrhage along the seat belt in motor vehicle accidents is called the seat belt sign (SBS). The risk of organ injuries is especially high when abdominal SBS is located above the anterior superior iliac spine (ASIS). The purpose of this study analyzed the physical and radiographic factors of healthy volunteers sit on car seat that affect initial position of abdominal seat belt, namely "lap belt", related to the seat belt injury. This study was examined prospectively relation between physical characteristics of one hundred healthy volunteers and lap belt position sitting the car seat. Physical findings were clarified age, sex, height, body mass index (BMI), and waist circumference. Radiographical findings were measured lumber lordosis (LL), sacral slope (SS), and initial lap belt position by marking with lead tape for the center and ASIS of the lap belt installed on the driver's car seat. In the lateral X-ray image, we measured the horizontal distance (X-value) and vertical distance (Z-value) from the ASIS to the central marker. The lap belt angle was determined to measure the angle between the horizontal line and the straight line connecting the upper edges of the markers. Statistical analysis of the relationships between physical characteristics and radiological findings was performed. X-value and Z-value were positively correlated with body weight, BMI, and waist circumference, while the lap belt angle was negatively correlated with body weight, BMI, and waist circumference. The relationship between physical characteristics and the initial position of seat belt was analyzed. Since the lap belt is positioned higher than the ASIS in occupants with a high BMI, it is likely to cause seat belt injury. This analysis can help to develop safer seat belts and to enlighten car occupants.

Patients With Preoperative Cervical Deformity Experience Similar Clinical Outcomes to Those Without Deformity Following 1-3 Level Anterior Cervical Decompression and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim was to compare the outcomes of patients with incompletely corrected cervical deformity against those without deformity following short-segment anterior cervical decompression and fusion for clinically significant radiculopathy or myelopathy.

SUMMARY OF BACKGROUND DATA

Cervical deformity has increasingly been recognized as a driver of disability and has been linked to worse patient-reported outcomes measures (PROMs) after surgery.

METHODS

Patients 18 years or above who underwent 1-3 level anterior cervical decompression and fusion to address radiculopathy and/or myelopathy at a single institution between 2014 and 2018 with at least 1 year of PROMs were reviewed. Patients were categorized based on cervical deformity into 2 groups: sagittal vertebral axis (cSVA) ≥40 mm as the deformity group, and cSVA <40 mm as the nondeformity group. Patient demographics, surgical parameters, preoperative and postoperative radiographs, and minimum 1-year PROMs were compared.

RESULTS

Of the 230 patients, 191 (83%) were in the nondeformity group and 39 (17%) in the deformity group. Patients with deformity were more likely to be male (69.2% vs. 40.3%, P<0.001) and have a greater body mass index (32.8 vs. 29.7, P=0.028). The deformity group had significantly greater postoperative cSVA (44.2 vs. 25.1 mm, P<0.001) but also had significantly greater ∆cSVA (-4.87 vs. 0.25 mm, P=0.007) than the nondeformity group. Both groups had significant improvements in visual analog scale arm, visual analog scale neck, Short-Form 12 Physical Component Score, and neck disability index (NDI) (P<0.001). However, the deformity group experienced significantly greater ∆NDI and ∆mental component score (MCS)-12 scores (-19.45 vs. -11.11, P=0.027 and 7.68 vs. 1.32, P=0.009).

CONCLUSIONS

Patients with preoperative cervical sagittal deformity experienced relatively greater improvements in NDI and MCS-12 scores than those without preoperative deformity. These results suggest that complete correction of sagittal alignment is not required for patients to achieve significant clinical improvement.

LEVEL OF EVIDENCE

III.

The impact of lumbar alignment targets on mechanical complications after adult lumbar scoliosis surgery

PURPOSE

The purpose of this study was to determine the discriminatory ability of age-adjusted alignment offset and the global alignment and proportion (GAP) score parameters to predict postoperative mechanical complications.

METHODS

Surgical patients from the Adult Symptomatic Lumbar Scoliosis cohort were reviewed at 2 year follow up. Age-adjusted alignment offsets and GAP parameters were calculated for each patient. A series of nonlinear logistic regression models were fit, and the odds of mechanical complications were calculated. The discriminatory ability of the GAP score, GAP score parameters, and age-adjusted alignment offsets were determined plotting receiver operative characteristic (ROC) with the C statistic (AUC).

RESULTS

A total of 165 patients were included. A total of 49 mechanical complications occurred in 41 patients (21 proximal junctional kyphosis and 28 pseudoarthrosis). The GAP score had no discriminatory ability in this cohort. Relative lumbar lordosis 15 degrees greater than ideal lumbar lordosis was associated with greater mechanical complications. A lumbar distribution index of 90% was associated with fewer mechanical complications compared to a lumbar distribution index of 65%. Age-adjusted offset alignment targets had no discriminatory ability to predict mechanical complications.

CONCLUSION

Radiographic alignment targets using either age-adjusted alignment target offset or GAP score parameters had minimal ability to predict mechanical complications in isolation. Mechanical complications following adult spinal deformity surgery are complex, and patient factors play a critical role. Clinical trial registeration This study was registered at ClinicalTrials.gov (number NCT00854828) in March 2009.

Association with sagittal alignment and osteoporosis-related fractures in outpatient women with osteoporosis

The baseline sagittal vertical axis (SVA) and pelvic tilt (PT) are independent risk factors of osteoporosis-related fractures in women with osteoporosis. We clarified the SVA and PT to predict the incidence of osteoporosis-related fractures.

PURPOSE

Sagittal alignment with osteoporosis women deteriorates with advancing age and sagittal alignment may indicate osteoporosis-related fractures in the future. However, whether the sagittal alignment predicts future osteoporosis-related fracture in patients with osteoporosis has not been clarified. We aimed to investigate the association between sagittal alignment and future osteoporosis-related fractures.

METHODS

This was a retrospective cohort study. Of the 313 participants (mean follow-up period, 2.9 years), 236 were included in the analysis. At baseline, we measured bone mineral density (BMD) of the lumbar spine and the femoral neck, sagittal vertical axis (SVA), thoracic kyphosis, pelvic incidence minus lumbar lordosis, sacral slope, pelvic tilt (PT), geriatric locomotive function scale (GLFS), two-step value, and stand-up test. The information on medications and the duration of treatment were reviewed from the medical records. Additionally, participants reported their history of falls at baseline. Multiple logistic regression analysis was used to determine the association of future osteoporosis-related fracture, and adjusted Odds ratios (OR) and 95% confidence interval (CI) were calculated with all predictors as covariates. All continuous variables were calculated using standardized OR (sOR).

RESULTS

Osteoporosis-related fractures occurred in 33 of 313 participants (10.5%). Multiple logistic regression analysis showed that a history of falls (OR =4.092, 95% CI: 1.029-16.265, p =0.045), SVA (sOR =4.228, 95% CI: 2.118-8.439, p <0.001), and PT (sOR =2.497, 95% CI: 1.087-5.733, p =0.031) were independent risk factors for future osteoporosis-related fractures.

CONCLUSIONS

This study revealed the SVA and PT to predict osteoporosis-related fractures.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

UMIN000036516 (April 1, 2019).

"Reverse roussouly": cervicothoracic curvature ratios define characteristic shapes in adult cervical deformity

PURPOSE

To investigate normal curvature ratios of the cervicothoracic spine and to establish radiographic thresholds for severe myelopathy and disability, within the context of shape.

METHODS

Adult cervical deformity (CD) patients undergoing cervical fusion were included. C2-C7 Cobb angle (CL) and thoracic kyphosis (TK), using T2-T12 Cobb angle, were used as a ratio, ranging from -1 to + 1. Pearson bivariate r and univariate analyses analyzed radiographic correlations and differences in myelopathy(mJOA > 14) or disability(NDI > 40) across ratio groups.

RESULTS

Sixty-three CD patients included. Regarding CL:TK ratio, 37 patients had a negative ratio and 26 patients had a positive ratio. A more positive CL:TK correlated with increased TS-CL(r = 0.655, p =  < 0.001)and mJOA(r = 0.530, p = 0.001), but did not correlate with cSVA/SVA or NDI scores. A positive CL:TK ratio was associated with moderate disability(NDI > 40)(OR: 7.97[1.22-52.1], p = 0.030). Regression controlling for CL:TK ratio revealed cSVA > 25 mm increased the odds of moderate to severe myelopathy and cSVA > 30 mm increased the odds of significant neck disability. Lastly, TS-CL > 29 degrees increased the odds of neck disability by 4.1 × with no cutoffs for severe mJOA(p > 0.05).

CONCLUSIONS

Cervical deformity patients with an increased CL:TK ratio had higher rates of moderate neck disability at baseline, while patients with a negative ratio had higher rates of moderate myelopathy clinically. Specific thresholds for cSVA and TS-CL predicted severe myelopathy or neck disability scores, regardless of baseline neck shape. A thorough evaluation of the cervical spine should include exploration of relationships with the thoracic spine and may better allow spine surgeons to characterize shapes and curves in cervical deformity patients.

Systemic Risk Factors for Adult Spinal Deformity (ASD): A Retrospective Analysis of 48 Patients

Introduction: Adult spinal deformity (ASD) results in significant patient morbidity and burden to quality of life. The degree to which systemic risk factors and comorbidities that contribute to ASD affect specific spinopelvic parameters is not well-documented. We determine the extent to which preoperative risk factors may contribute to spinopelvic parameters associated with ASD.

Methods: Retrospective single-center study of 48 patients with ASD. Analysis of variance (ANOVA) linear regression analysis was performed to evaluate correlation between systemic comorbidities (obesity, arterial hypertension (HTN), hyperlipidemia (HLD), cardiomyopathy, diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), and asthma) and the following radiographic parameters: pelvic incidence (PI), lumbar lordosis (LL), C7 sagittal vertical axis (C7SVA), and the T10-L2 sagittal cobb angle.

Results: A total of 48 patients were included with mean C7SVA of 79.6 mm (SD: 63, range: 43-254), mean LL of 32.9° (SD: 15.9, range: -14 to 78), T10-L2 sagittal cobb angle of 3° (SD: 12.7, range: -24 to 30), and PI was 49° (SD: 10.7, range: 21 to 77). Only DM correlated with sagittal imbalance with high C7SVA and PI-LL mismatch. The beta coefficient for DM and preoperative C7SVA was 0.49, t=3.16, p=0.003, preoperative PI-LL mismatch standardized beta coefficient was -0.4, t=-2.38, p=0.022, and preoperative T10-L2 sagittal cobb standard beta coefficient was -0.07, t=-0.46, p=0.645. No significant correlations were found for asthma, COPD, HTN, HLD, or cardiomyopathy.

Conclusions: Diagnosis of DM was found to correlate with pathologic C7SVA and significant PI-LL mismatch associated with ASD. HTN, HLD, cardiomyopathy, obesity, and pulmonary disease did not correlate with radiographic findings of sagittal imbalance.

Does minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) influence functional outcomes and spinopelvic parameters in isthmic spondylolisthesis?

PURPOSE

We assessed the efficacy of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in patients with low-grade isthmic spondylolisthesis.

METHODS

We included 24 symptomatic patients who underwent MIS-TLIF between December 2017 and December 2020. Patients were followed up clinically by the Oswestry Disability Index (ODI) and Visual Analogue Scale (VAS) for back and VAS for leg pain, as well as radiological radiographs after 6 weeks, 6 months, and at final follow-up (at least 12 months). Measured parameters included C7 sagittal vertical axis (SVA), pelvic tilt (PT), pelvic incidence (PI), sacral slope (SS), Meyerding slip grades, lumbar lordosis (LL), L1-L4 angle, L4-S1 angle, and segmental lordosis (SL) of the affected segment. The mismatch between the PI and LL was also measured.

RESULTS

VAS for back, VAS for leg pain, and ODI significantly improved postoperatively (all p < 0.001). We observed significantly decreased mean values of PT and slip percentage and increased mean values of SS and LL (all p < 0.05). We observed a significant reduction in L1-L4 lordosis and a significant increase in L4-S1 lordosis. The final PT, SS, and LL (total and L1-L4) were significantly higher in group III patients (n = 15) than the values of group II patients (n = 9). None of the patients became unbalanced postoperative, and all patients had a normal matching between the PI and the LL postoperatively.

CONCLUSIONS

MIS-TLIF is a safe procedure for managing low-grade isthmic spondylolisthesis with significant improvement in clinical and radiological outcomes. It can correct and maintain a proper spinopelvic alignment.

Mid-term changes in spinopelvic sagittal alignment in lumbar spinal stenosis with coexisting degenerative spondylolisthesis or scoliosis after minimally invasive lumbar decompression surgery: minimum five-year follow-up

BACKGROUND CONTEXT

Recently, the number of patients with lumbar spinal stenosis (LSS) who present with a coexisting spinal deformity such as degenerative spondylolisthesis (DS) and scoliosis (DLS) has been increasing. Lumbar decompression without fusion can lead to a reactive improvement in the lumbar and sagittal spinopelvic alignment, even if a sagittal imbalance exists preoperatively. However, the mid- to long-term impact of the coexistence of DS and DLS on the change in sagittal spinopelvic alignment and clinical outcomes after decompression surgery remains unknown.

PURPOSE

This study aimed to investigate whether the coexistence of DS or DLS in patients with LSS is associated with differences in radiological and clinical outcomes after minimally invasive lumbar decompression surgery.

STUDY DESIGN/SETTING

A retrospective analysis of prospectively collected data.

PATIENT SAMPLE

A total of 169 patients who underwent minimally invasive lumbar decompression surgery and follow-up >5 years postoperatively.

OUTCOME MEASURES

Self-report measures: Low back pain (LBP) and/or leg pain and/or leg numbness visual analog scale (VAS) scores and the Japanese Orthopedic Association scores.

PHYSIOLOGIC MEASURES

Standing sagittal spinopelvic alignment.

METHODS

In total, 81 patients with LSS, 50 patients with LSS and DS (≥3 mm anterior slippage), and 38 patients with LSS and DLS (≥15° coronal Cobb angle) were included in the current study. Clinical and radiological outcome results before surgery and at 2 and 5 years after surgery were compared among the groups.

RESULTS

In patients with LSS with coexisting DS, the clinical outcomes at 2, and 5 years after surgery were similar to those of patients with only LSS. In patients with LSS with coexisting DLS, the VAS LBP and leg pain at 2 years after surgery was significantly higher (34.7 vs. 27.8, p=0.014; 27.8 vs. 14.7, p=0.028) and the achievement rate of the minimal clinically important difference in VAS LBP and leg pain was significantly lower than that of the LSS group (36.1% vs. 54.2%, p=0.036; 58.3% vs. 69.9%, p=0.10). The clinical outcomes except VAS leg numbness at 5 years after surgery were similar to those of patients with only LSS. The reoperation rate of the DS group was significantly lower than that of the LSS group (4.0% vs. 14.8%; p=0.01); however, the reoperation rate of the DLS group was comparable to that of the LSS group (15.8% vs. 14.8%; p=0.493). Lumbar lordosis (LL), sacral slope, pelvic tilt, and pelvic incidence-LL had significantly improved and been maintained for 5 years after the surgery in both the DS and the DLS groups. The sagittal vertical axis had improved at two-year follow-up; however, no significant difference was observed at the 5-year follow-up in both the DS, and the DLS groups.

CONCLUSIONS

Mid-term clinical outcomes in patients with LSS with and without deformity were comparable. Lumbar decompression without fusion can result in a reactive improvement in the lumbar and sagittal spinopelvic alignment, even with coexisting DS or DLS. Minimally invasive surgery could be considered for most patients with LSS.

Risk factors for coronal oblique take-off following adult spinal deformity surgery using lateral lumbar interbody fusion and open posterior corrective fusion

PURPOSE

To evaluate risk factors associated with oblique take-off (OT) following lateral lumbar interbody fusion (LLIF) for adult spinal deformity.

METHODS

Thirty-nine consecutive patients (mean age 67.9 years) with scoliosis of the lumbar curve (> 30°) were evaluated. Multilevel LLIF, followed by open thoraco-pelvic posterior corrective fusion after 1 week, was performed. We defined OT as a distance of > 25 mm between the C7 plumb line and the central sacral vertical line and examined risk factors by dividing the patients into the OT and non-OT groups.

RESULTS

OT occurred in 11 patients (28%), all showing a tilt to the convex side. The correction rate of the lumbar curve was approximately 70% range for both groups, which indicated good correction. Preoperative radiographs showed a high L1-central sacral vertical line in the standing position; high L5 tilt in the supine position; high L3, L4, and L5 tilts to the convex side in the supine-bending position; and a high L4 vertebral wedge on the convex side in OT cases. Multiple logistic regression analysis showed that an L4 tilt to the concave side in the bending position was the most effective predictor of OT (odds ratio = 1.104, P = 0.047). For a cutoff value of 16°, the sensitivity and specificity were 73% and 61%, respectively, according to the receiver operating characteristic curve analysis (area under the curve = 0.73).

CONCLUSION

OT occurred in 28% of adult scoliosis patients following LLIF. An L4 tilt > 16° to the concave side in the bending position was the most valuable risk factor.

LEVEL OF EVIDENCE

IV.

Impact of radiologic variables on item responses of ODI, SRS22 and SF-36. in adult spinal deformity patients: differential item functioning (DIF) analysis results from a multi-center database

PURPOSE

To determine if responses given to each question of the Scoliosis Research Society-22 (SRS22), Oswestry disability index (ODI) and Short Form-36 (SF-36) questionnaires are influenced by the radiological parameters.

METHODS

Patients enrolled in a multi-centre prospectively collected adult spinal deformity database who had complete SRS22, ODI and SF-36 data at baseline and at one-year follow-up were analysed. The presence of a differential item function of each question within each score in relation to radiological parameters was analysed using a mixed Rasch model with the radiological threshold value(s) determined.

RESULTS

Of those patients analysed (n = 1745; 1406 female, average age 51.0 ± 19.8 years), 944 were surgically and 801 were non-surgically treated. For the SRS22, questions (Q) 3, 5 and 18 were sensitive to almost all radiological parameters and the overall score was found sensitive to the Cobb angle. For the ODI, Q3, 6, 9 and 10 were not sensitive to any radiologic parameters whereas Q4 and 5 were sensitive to most. In contrast, only 3 of the SF-36 items were sensitive to radiological parameters.

CONCLUSIONS

78% of the SRS-22, 60% of the ODI and 8% of the questions in the SF-36 are sensitive to radiological parameters. Sagittal imbalance is independently associated with a poor overall outcome, but affects mental status and function more than pain and self-image. The assembly of questions responsive to radiological parameters may be useful in establishing a connection between changes in radiologic parameters and HRQL.

Radiographic comparison of lordotic and hyperlordotic implants in L5-S1 anterior lumbar interbody fusion

OBJECTIVE

Anterior lumbar interbody fusion (ALIF) used at the lumbosacral junction provides arthrodesis for several indications. The anterior approach allows restoration of lumbar lordosis, an important goal of surgery. With hyperlordotic ALIF implants, several options may be employed to obtain the desired amount of lordosis. In this study, the authors compared the degree of radiographic lordosis achieved with lordotic and hyperlordotic ALIF implants at the L5-S1 segment.

METHODS

All patients undergoing L5-S1 ALIF from 2 institutions over a 4-year interval were included. Patients < 18 years of age or those with any posterior decompression or osteotomy were excluded. ALIF implants in the lordotic group had 8° or 12° of inherent lordosis, whereas implants in the hyperlordotic group had 20° or 30° of lordosis. Upright standing radiographs were used to determine all radiographic parameters, including lumbar lordosis, segmental lordosis, disc space lordosis, and disc space height. Separate analyses were performed for patients who underwent single-segment fixation at L5-S1 and for the overall cohort.

RESULTS

A total of 204 patients were included (hyperlordotic group, 93 [45.6%]; lordotic group, 111 [54.4%]). Single-segment ALIF at L5-S1 was performed in 74 patients (hyperlordotic group, 27 [36.5%]; lordotic group, 47 [63.5%]). The overall mean ± SD age was 61.9 ± 12.3 years; 58.3% of patients (n = 119) were women. The mean number of total segments fused was 3.2 ± 2.6. Overall, 66.7% (n = 136) of patients had supine surgery and 33.3% (n = 68) had lateral surgery. Supine positioning was significantly more common in the hyperlordotic group than in the lordotic group (83.9% [78/93] vs 52.3% [58/111], p < 0.001). After adjusting for differences in surgical positioning, the change in lumbar lordosis was significantly greater for hyperlordotic versus lordotic implants (3.6° ± 7.5° vs 0.4° ± 7.5°, p = 0.048) in patients with single-level fusion. For patients receiving hyperlordotic versus lordotic implants, changes were also significantly greater for segmental lordosis (12.4° ± 7.5° vs 8.4° ± 4.9°, p = 0.03) and disc space lordosis (15.3° ± 5.4° vs 9.3° ± 5.8°, p < 0.001) after single-level fusion at L5-S1. The change in disc space height was similar for these 2 groups (p = 0.23).

CONCLUSIONS

Hyperlordotic implants provided a greater degree of overall lumbar lordosis restoration as well as L5-S1 segmental and disc space lordosis restoration than lordotic implants. The change in disc space height was similar. Differences in lateral and supine positioning did not affect these parameters.

The Impact of Surgical Approach on Sagittal Plane Alignment in Patients Undergoing One- or Two- Level Fusions for Degenerative Pathology: A Multicenter Radiographic Evaluation 6 Months Following Surgery

OBJECTIVE

Interbody fusion procedures, including transforaminal (TLIF), posterior (PLIF), anterior (ALIF), and lateral (LLIF), effectively treat lumbar degenerative pathology and provide spinopelvic balance. The objective of this study is to compare changes in spinopelvic parameters 6 months following 1-2 level TLIF, PLIF, ALIF, and LLIF.

METHODS

This retrospective study included 18 centers across the United States. Patients were included in the study if they underwent a 1- or 2-level primary lumbar fusion for degenerative pathology. Preoperative and 6-month postoperative lumbar anteroposterior and lateral lumbar plain radiograph measurements included: pelvic incidence, pelvic tilt, lumbar lordosis from L1-S1, and segmental lordosis of each segment between L1 and S1.

RESULTS

A total of 474 patients met inclusion criteria, with 632 levels that underwent fusion. Of these, 181 patients underwent an ALIF/LLIF on 381 levels, and 188 underwent a TLIF/PLIF on 252 levels. ALIF/LLIF procedures resulted in significantly more segmental lordosis (P < 0.001) and global lumbar lordotic alignment change (P < 0.01) compared with TLIF/PLIF procedures. Whether patients' alignment was preserved versus worsened was not significantly predicted by type of procedure. Similarly, whether patients' alignment was restored versus not corrected was not significantly predicted by procedure.

CONCLUSIONS

In this large-scale multicenter study of lumbar fusion patients presenting with degenerative lumbar pathology, anteriorly placed grafts (ALIF/LLIF) led to a greater likelihood of patients being preserved rather than worsened in their spinopelvic mismatch. Posteriorly placed TLIF or PLIF grafts tended to worsen lordosis both segmentally and globally, yet even the anterior grafts only modestly improved those 2 same measurements.

Analysis of Risk Factors for Adjacent Segment Degeneration after Minimally Invasive Transforaminal Interbody Fusion at Lumbosacral Spine

Background. Adjacent segment degeneration (ASD) has been considered as a serious complication from changes in the biological stress pattern after spinal fusion. The sagittal balance significantly associated with lumbar loading is largely dependent on L5-S1 segment. However, the evidence indicating risk factors for radiological and symptomatic ASD after minimally invasive transforaminal interbody fusion (MIS-TLIF) remains insufficient. Methods. This single-central retrospective study recruited patients with lumbosacral degeneration receiving MIS-TLIF at the L5-S1 level from January 2015 to December 2018. The targeted variables included demographic information, radiological indicators, surgery-related parameters, and patient-reported outcomes (PROs) extracted from the electronic medical system by natural language processing. In these patients, a minimum of 3-year follow-up was done. After reviewing the preoperative and postoperative follow-up digital radiographs, patients were assigned to radiological ASD group (disc height narrowing ≥3 mm, progressive slipping ≥3 mm, angular motion >10°, and osteophyte formation >3 mm), symptomatic ASD group, and control group. We identified potential predictors for radiological and symptomatic ASD with the service of stepwise logistic regression analysis. Results. Among the 157 consecutive patients treated with MIS-TLIF in our department, 16 cases (10.2%) were diagnosed with radiological ASD at 3-year follow-up. The clinical evaluation did not reveal suspicious risk factors, but several significant differences were confirmed in radiological indicators. Multivariate logistic regression analysis showed postoperative PI, postoperative DA, and ∆PI-LL in radiological ASD group were significantly different from those in control group. Nevertheless, for patients diagnosed with simultaneously radiological and symptomatic ASD, postoperative DA and postoperative PT as risk factors significantly affected the clinical outcome following MIS-TLIF. Conclusion. In this study, while approximately 10% of lumbosacral degenerations develop radiographic ASD, prognosis-related symptomatic ASD was shown not to be a frequent postoperative complication. Postoperative PI, postoperative DA, and mismatched PI-LL are risk factors for radiological ASD, and postoperative DA and postoperative PT are responsible for the occurrence of symptomatic ASD following MIS-TLIF. These radiological risk factors demonstrate that restoration of normal sagittal balance is an effective measure to optimize treatment strategies for secondary ASD prevention.

Spinopelvic Characteristics Normalize 1 Year After Total Hip Arthroplasty: A Prospective, Longitudinal, Case-Controlled Study

BACKGROUND

The presence of hip osteoarthritis is associated with abnormal spinopelvic characteristics. This study aimed to determine whether the preoperative, pathological spinopelvic characteristics normalize at 1 year after total hip arthroplasty (THA).

METHODS

This was a prospective, longitudinal, case-control, matched cohort study. Forty-seven patients undergoing THA underwent preoperative and 1-year postoperative assessments. This group was matched with regard to age, sex, and body mass index with 47 controls (volunteers) with well-functioning hips. All participants underwent clinical and radiographic assessments including lateral radiographs in standing, relaxed-seated, and deep-flexed-seated positions. Spinopelvic characteristics included change in lumbar lordosis (ΔLL), change in pelvic tilt (ΔPT), and hip flexion (change in pelvic-femoral angle, ΔPFA) when moving from a standing position to either of the seated positions. Spinopelvic hypermobility was defined as ΔPT > 30° between the standing and upright-seated positions.

RESULTS

Patients who underwent THA, compared with the control group, preoperatively demonstrated less mean change in hip flexion (ΔPFA, -54.8° ± 17.1° compared with -68.5° ± 9.5°; p < 0.001), greater mean change in pelvic tilt (ΔPT, 22.0° ± 13.5° compared with 12.7° ± 8.1°; p < 0.001), and greater mean lumbar movement (ΔLL, -22.7° ± 15.5° compared with -15.4° ± 10.9°; p = 0.015) transitioning from a standing position to an upright-seated position. After THA, these differences were no longer present between the THA group and the control group: the mean postoperative changes were -65.8° ± 12.5° (p = 0.256) for ΔPFA, 14.3° ± 9.5° (p = 0.429) for ΔPT, and -15.3° ± 10.6° (p = 0.966) for ΔLL. The higher prevalence of spinopelvic hypermobility in the THA group compared with the control group that was observed preoperatively (21% compared with 0%; p = 0.009) was no longer present after THA (6% compared with 0%; p = 0.194). Similar results were found moving from a standing position to a deep-seated position after THA.

CONCLUSIONS

Preoperative spinopelvic characteristics that contribute to abnormal mechanics can normalize after THA following improvement in hip flexion. This leads to patients having the expected hip, pelvic, and spinal flexion as demographically matched controls, thus potentially eliminating abnormal mechanics that contribute to the development or exacerbation of hip-spine syndrome.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Correction of the pelvic incidence using a bilateral extending pelvic osteotomy: a proof of concept study

INTRODUCTION

The aim of this proof of concept human cadaver study was to quantify the effect of a bilateral extending pelvic osteotomy (BEPO) on pelvic incidence (PI) as a potential alternative for a pedicle subtraction osteotomy (PSO) in patients with severe spinal sagittal malalignment.

MATERIALS AND METHODS

10 fresh frozen human cadavers were treated with the BEPO technique. CT images were made before and after the osteotomy and pure sagittal images were created on which PI was measured.

RESULTS

The mean pre-osteotomy PI was 47.9° (range 36.4-63.9) and the mean post-osteotomy PI was 36.5° (range 22.1-54.4). The mean correction was - 10.4° with a range of - 8.4° to - 17.3° (p = 0.03), which resulted in a mean decrease of 23% in the PI (range 16-42).

CONCLUSIONS

There was a feasible and effective correction of PI using the BEPO technique on the os ilium. This was a preliminary cadaveric study. No conclusions could be made on global sagittal alignment. We postulate that an extending osteotomy of the ilium could be a potential alternative for a PSO reducing the complexity of spine surgery in patients with severe spinal sagittal malalignment.

Computer Simulated Enhancement and Planning, Robotics and Navigation With Patient Specific Implants and 3-D Printed Cages

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVES

Pre and postop Measurement Testing. This is a retrospective study of 33 consecutive interbody spacers in 21 patients who underwent pre, intra, and postoperative measurement of the middle column to determine if this would lead to more precise restoration of middle column height and spacer fit. Scaled transparencies of the pre-operative simulation of angular correction and spacer geometry could be overlayed on the post-operative imaging studies.

METHODS

Multiple Observers Measurement Testing. 33 consecutive vertebral levels requiring interbody spacers for multilevel deformities had middle column height pre and post operatively measured by 3 blinded observers. The preoperative and postoperative measurements were compared using a linear regression analysis and Pearson product-moment correlation.

RESULTS

Pre and postop Measurement Testing: Thirty-three interbody devices in 21 patients had pre-operative planning, simulation of cage dimensions to determine the proper cage fit which would provide for the desired correction of foraminal height and sagittal balance parameters. The simulated preoperative plan overlayed the final post-operative radiograph and was a near-perfect match in 20 of 21 patients (95.2%). Multiple Observers Measurement Testing: A Pearson product-moment correlation was run between each individual's pre-op and post-op middle column measurements. There was a strong, positive correlation between pre-operative and post-operative measurements, which was statistically significant (r = 0.903, n = 33, P < 0.001).

CONCLUSIONS

This consecutive series of 33 cases demonstrated the utility of measuring the preoperative middle column length in predicting the optimal height of the spacers, intervertebral disks, and posterior vertebral body height simultaneously restoring sagittal and coronal plane alignment.

The Effect of Systemic Tranexamic Acid on Hypercoagulable Complications and Perioperative Outcomes Following Three-Column Osteotomy for Adult Spinal Deformity

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Thoracolumbar 3-column osteotomy (3CO) is a powerful technique for correction of rigid adult spinal deformity (ASD). However, it can be associated with high-volume blood loss. This study seeks to investigate the efficacy and safety of tranexamic acid (TXA) in 3CO ASD patients.

METHODS

ASD patients who underwent 3CO from 2006 to 2019 were retrospectively reviewed. Outcomes were compared between TXA and non-TXA patients, and TXA doses.

RESULTS

A total of 365 ASD patients were included: 181 TXA and 184 non-TXA. The mean age was 64.6 years and 60.5% were female. Operative time was shorter in the TXA group (295.6 vs 320.2 minutes, P < .001). However, TXA was not associated with shorter operative time (β = -6.5 minutes, 95% CI -29.0 to 15.9, P = .567) after accounting for surgeon experience. There was no difference in blood loss (2020.2 vs 1914.1 mL, P = .437) between groups. Overall complications (37.0% vs 33.2%, P = .439), including hypercoagulable (2.2% vs 3.8%, P = .373) and cardiac (13.3% vs 7.1%, P = .050) complications were similar between groups. TXA was not independently associated with blood loss or TXA-related complications. Both groups had comparable intensive care unit (2.5 vs 2.0 days, P = .060) and hospital (8.9 vs 8.2 days, P = .190) stays. There were no differences in outcomes between TXA dosing subgroups.

CONCLUSIONS

Systemic TXA use during 3CO for ASD surgery was not associated with decreased blood loss. TXA patients had shorter operative times, but this was driven mainly by surgeon experience on multivariate analysis. Routine use of TXA is safe and does not increase the incidence of hypercoagulable complications even at high doses.

Low back pain significantly influences locomotive syndrome in older people: Evaluation using the 3-stage categories

BACKGROUND

The Japanese Orthopaedic Association (JOA) introduced the concept of locomotive syndrome (LS), which indicates a decline in mobility function by musculoskeletal disorders with new 3-staged category. Additionally, sarcopenia indicates a decline in the quantity and/or quality of skeletal muscle. However, the relationship between low back pain (LBP) and LS or sarcopenia in older people has not been sufficiently understood. This study aimed to investigate the association between them through a cross-sectional locomotorium survey.

METHODS

A total of 302 participants were drawn from the aquatic exercise participants in a rural area of Japan. The body mass index, body fat percentage, skeletal muscle mass index (SMI), spinal inclination angle (SIA), grip strength, timed up-and-go test (TUG), and maximum stride of the participants were measured. LBP and LBP-related quality of life (QOL) were evaluated using the Oswestry Disability Index (ODI), visual analogue scale (VAS) of LBP, and the Short-Form 8 (SF-8). Associations between the investigating parameters and sarcopenia or LS were analyzed.

RESULTS

There were no significant differences in the findings except grip strength between the non-sarcopenia and sarcopenia groups. However, the LS group showed significantly larger SIA, higher ODI, higher VAS of LBP, lower physical component score (PCS) of the SF-8, longer time in TUG, and lower value in maximum stride than the non-LS group. In addition, the ODI and PCS of the SF-8 significantly deteriorated as the LS stage progressed, and the GLFS-25 score was significantly correlated with ODI (r = 0.706, p < 0.001) and PCS (r = -0.643, p < 0.001) scores.

CONCLUSIONS

LBP, LBP-related QOL, and physical performance were found to be significantly associated with LS, not sarcopenia, with LBP-related QOL and physical function being closely correlated with 3-stage categories of LS. Thus, these results suggested that LBP is a key factor for LS prevalence.

Bone Fusion Morphology after Circumferential Minimally Invasive Spine Surgery Using Lateral Lumbar Interbody Fusion and Percutaneous Pedicle Screws without Bone Grafting in the Thoracic Spine: A Retrospective Study

Background and Objectives: This study aimed to investigate the process and morphology of thoracic and lumbosacral bone fusion in patients with adult spinal deformity (ASD) who underwent circumferential minimally invasive spine surgery (CMIS) by lateral lumbar interbody fusion (LLIF) and percutaneous pedicle screws (PPSs) without bone grafting in the thoracic spine and who have risk factors for bone fusion failure in the thoracic spine. Materials and Methods: This retrospective study included 61 patients with spinal deformities (46 women and 15 men) who underwent CMIS with LLIF and PPSs at our hospital after 2016 and completed a 3-year postoperative follow-up. The rate and morphology of bone fusion and rod fracture rate in the thoracic and lumbosacral vertebrae were evaluated. Patients were divided into the thoracic spine spontaneous bone fusion group and the bone fusion failure group. The data of various spinopelvic parameters and the incidence of complications were compared. The vertebral body conditions in the thoracic spine were classified as less degenerative (type N), osteophyte (type O), and diffuse idiopathic skeletal hyperostosis (DISH) (type D). Results: After three postoperative years, the bone fusion rates were 54%, 95%, and 89% for the thoracic, lumbar, and lumbosacral spine, respectively. Screw loosening in the thoracic vertebrae was significantly higher in the bone fusion failure group, while no significant differences were observed in the spinopelvic parameters, Oswestry Disability Index (ODI), and rate of proximal junctional kyphosis and rod fractures. Type N vertebral body condition and screw loosening were identified as risk factors for spontaneous bone fusion failure in the thoracic spine. Conclusion: This study indicated that spontaneous bone fusion is likely to be obtained without screw loosening, and even if bone fusion is not obtained, there is no effect on clinical results with the mid-term (3-year) results of CMIS without bone grafting in the thoracic spine.

Correlation Between Different Sagittal Parameters in Patients With Degenerative Kyphosis

Objective

To explore the relationship between different sagittal parameters and identify the fitting formula of spino-pelvic parameters in patients with degenerative kyphosis (DK).

Summary of Background

Sagittal balance is increasingly recognized as a predictor of clinical outcomes in patients with DK, while the relationship between different sagittal parameters in patients with DK remains unidentified.

Methods

A retrospective study with 279 participants was conducted. There were 168 DK patients which were divided into a sagittal balance group (SB:52 cases) and sagittal imbalance (SIB:116 cases). Radiographic measurements included thoracolumbar kyphosis (TLK), lumbar lordosis (LL), thoracic kyphosis (TK), pelvic incidence (PI), and pelvic tilt (PT). The correlations were analyzed between different sagittal parameters.

Results

There were significant differences between the SB and SIB groups in terms of TLK, LL, PI-LL, PT, SVA, sacral slope (SS), and TK. For patients with DK, the LL was correlated with PT and TK. The linear regression was LL = 22.76−0.28 × PT + 0.62 × TK. In the SB group, TK was the influencing factor for LL and the linear regression analysis showed that LL = 33.57 + 0.33 × TK. While in the SIB group, PT and TK were in synergistic effect with PI-LL, the linear regression analysis showed that LL = 22.76−0.28 × PT + 0.62 × TK.

Conclusion

From the present study, we can see that LL has a significant correlation with PT and TK in patients with DK, while in SB, the LL was only correlated with TK. Therefore, the correction of LL in a different group should be calculated to avoid the incidence of proximal junction kyphosis (PJK).

Metal failure and nonunion at L5-S1 after long instrumented fusion distal to pelvis for adult spinal deformity: Anterior versus transforaminal interbody fusion

PURPOSE

Pseudoarthrosis and metal failure at L5-S1 following long fusion surgery for adult spinal deformity (ASD) remain major issues. Few studies report on which anterior column support technique is better in terms of achieving fusion and avoiding metal failures. Our study aimed to evaluate the fusion status and metal failure rate at L5-S1 after anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF).

METHODS

The study population included patients aged >50 years who underwent surgery for ASD. Anterior column supports at L5-S1 using ALIF and TLIF were compared with ≥ 2-year follow-up. Fusion status on 2-year computed tomography (CT) scan, metal failure, visual analog scale (VAS), and Oswestry disability index (ODI) were evaluated.

RESULTS

98 patients were included in this study (53 ALIF group and 45 TLIF group). We achieved solid fusion on 2-year CT scans in 88.9% and 69.8% patients in the TLIF and ALIF group, respectively. Metal failure developed in nine (17.0%) and six (13.3%) patients in the ALIF and TLIF group, respectively. The most common failure type was unilateral L5-S1 rod fracture (7 and five patients in the ALIF and TLIF group, respectively). Only one patient with bilateral rod fractures in the ALIF group required revision surgery. There were no differences in the VAS and ODI scores at the last follow-up.

CONCLUSIONS

TLIF showed a better fusion rate than ALIF at L5-S1 after long instrumented fusion for ASD. However, the capacity to restore sagittal parameters was greater in the ALIF group. There were no differences between the groups regarding metal failure rate, revision surgery, or clinical outcomes.

Spinal-pelvic sagittal parameters in patients with gluteal muscle contracture: an imaging study

Background

Gluteal muscle contracture (GMC) may cause abnormal spinal alignment as well as hip and pelvic deformities. The spine-pelvis alignment of GMC patients is unclear. This study aimed to describe the spine-pelvis sagittal alignment in patients with GMC and to explore the impact of GMC on the pathogenesis of low back pain (LBP).

Methods

Radiological analysis was performed in 100 patients with GMC and 100 asymptomatic volunteers who acted as the control group. Sagittal parameters were measured by two independent raters and their averages were presented on lateral radiographs of the whole spine, including pelvic incidence (PI), sagittal vertical axis (SVA), pelvic tilt (PT), lumbar lordosis (LL), sacral slope (SS), thoracic kyphosis (TK), and the relationship between PI and LL (expressed as PI-LL). All cases were categorized into one of three classes based on the apex position of lumbar lordosis and were further divided into three groups by the PI value. The GMC and control parameters were compared and the correlations between the parameters in the GMC group were analysed.

Results

The PI value of the GMC group was significantly less than that of the control group (42.38 ± 10.90° vs 45.68 ± 7.49°, P < 0.05). There was no difference found between the key parameters (SVA, PT, and PI-LL), which correlated with outcomes in adult deformity. No differences of SS were found between the two groups (P > 0.05). The GMC group showed lower average LL (42.77 ± 10.97° vs 46.41 ± 9.07°) and TK (17.34 ± 9.50° vs 20.45 ± 8.02°) compared with the control group (P < 0.05). LL was correlated with PI, SS, PT, TK (P < 0.01) and SVA (P < 0.05). TK and SVA were not correlated with any parameters except LL and pairwise correlations were found among PI, SS, and PT. There were no differences found between the distributions of the lumbar lordosis apex of GMC and the control but the range of SS in apex groups 3 and 4 did differ. GMC patients had the most small-PI value (44%) while approximately 64% of asymptomatic individuals had a normal PI. Interobserver variability was sufficient for all parameters calculated by the intraclass correlation coefficient (ICC).

Conclusions

Gluteal muscle contracture causes a low PI which may contribute to low back pain. Patients with GMC present the same global sagittal spinal-pelvic balance as asymptomatic individuals due to a compensatory mechanism through excessive flat lumbar and thoracic curves. Future studies on the relationship between spinal-pelvic sagittal and coronal alignment and low back pain are needed to understand the mechanical forces involved in the onset of GMC.

Classification and citation analysis of the 100 top-cited articles on adult spinal deformity since 2011: A bibliometric analysis

BACKGROUND

Studies of the 100 most-cited articles are reported for many subjects. However, none has analyzed the article characteristics associated with high citation frequency. This study aims to (1) graphically depict characteristics of the 100 top-cited articles addressing adult spinal deformity (ASD), (2) diagram the association between articles according to subject and major topic medical subject headings (MeSHs), and (3) investigate whether major topic MeSH correlates with article citation frequency.

METHODS

The 100 top-cited ASD publications since 2011 were retrieved using a PubMed Central search on May 6, 2020. Using titles and abstracts, eight subject categories were identified: surgery, conservative treatment, normal values in spinopelvic alignment, review, cervical alignment, classification, compensatory mechanism, and spine-hip relationship. Sankey diagrams were used to organize the information. Network analysis was performed according to article subject and major topic MeSHs. Pearson's r was used to determine whether the weighted number of citations correlates with major topic MeSHs and the number of citations.

RESULTS

The average number of citations per article was 34.8 (range, 19-156). The most represented country was USA (n = 51). The most productive and highly cited journal was Spine (Phila Pa 1976) (n = 34; average, 38.2 citations per article). The most frequent subject categories and major topic MeSHs were "surgery" (n = 53) and "scoliosis" (weighted count, 9.8), while articles with the subject "compensatory" had the highest average number of citations (64.7). The most highly cited article, by Dr. F. Schwab in 2012, had 156 citations. Network analysis revealed the relationships between these articles according to major topic MeSHs. The weighted number of citations according to major topic MeSHs correlated significantly with article citation frequency (Pearson's r, 0.57; p < 0.001).

CONCLUSION

Multiple characteristics of the 100 top-cited ASD articles are presented in diagrams to guide evidence-based clinical decision-making in ASD.

Effects of preoperative sagittal spinal imbalance on pain after lateral lumbar interbody fusion

Sagittal misalignment has been associated with negative quality of life (QOL). However, there is no report on whether differences in preoperative sagittal misalignment in patients with lumbar degenerative diseases affect postoperative results after lateral lumbar interbody fusion (LLIF). We investigated whether preoperative sagittal alignment influences the correction of alignment after surgery and whether the preoperative sagittal alignment affects the rating of low back pain, leg pain, and leg numbness. The subjects were 81 patients (48 male, 33 females, average age at surgery 70.2 years) who underwent anterior-posterior combined surgery with LLIF and percutaneous pedicle screws from May 2018 to July 2020. Cluster analysis was performed using the preoperative sagittal vertical axis (SVA) value, and patients were classified into two groups (group 1; n = 30, SVA = 129.0 ± 53.4 mm, group 2; n = 51, SVA = 30.8 ± 23.5 mm). Baseline demographics and treatment data were compared between groups. Sagittal and pelvic parameters and pain scores, such as low back pain, leg pain, and leg numbness, were also compared. Operative time, blood loss, and length of hospital stay did not differ significantly between groups. The changes (Δ) in SVA and lumbar lordosis (LL) for all patients from before to after surgery were not significant (ΔSVA; p = 0.218, ΔLL; p = 0.189, respectively). The SVA, LL, and PI - LL changed significantly after the surgery in group 1, but no marked improvement in sagittal imbalance was obtained after LLIF surgery. The improvement in each pain score from before to after the surgery did not differ significantly between groups. LLIF surgery has a limited chance of recovering sagittal imbalance. However, postoperative low back pain, leg pain, and leg numbness may be improved by LLIF surgery, regardless of the preoperative sagittal alignment.

Correlação entre a gravidade da doença degenerativa lombar e o alinhamento espinopélvico

Objective  To evaluate the impact of the severity of lumbar degenerative disease (LDD) on sagittal spinopelvic alignment.

Methods  In total, 130 patients (mean age: 57 years; 75% female) with LDD-associated low-back pain were prospectively included. The severity of the LDD was defined by the following findings on anteroposterior and lateral lumbar spine radiographs: osteophytosis; loss of of height of the intervertebral disc; terminal vertebral plate sclerosis; number of affected segments; deformities; and objective instability. The disease was classified as follows: grade 0–absence of signs of LDD in the lumbar spine; grade I – signs of LDD in up to two segments; grade II – three or more segments involved; grade III – association with scoliosis, spondylolisthesis, or laterolisthesis. Spinopelvic radiographic parameters, including pelvic incidence (PI), lumbar lordosis (LL), discrepancy between the PI and LL (PI-LL), pelvic tilt (PT), and sagittal vertical axis (SVA), were analyzed according to the LDD grades.

Results  The radiographic parameters differed according to the LDD grades; grade-III patients presented higher SVA ( p  = 0.001) and PT ( p  = 0.0005) values, denoting greater anterior inclination of the trunk and pelvic retroversion when compared to grade-0 andgrade-I subjects. In addition, grade-III patients had higher PI-LL values, which indicates loss of PI-related lordosis, than grade-I subjects ( p  = 0.04).

Conclusion  Patients with more severe LDD tend to present greater spinopelvic sagittal misalignment compared to patients with a milder disease.

Correlation of spinopelvic parameters with functional outcomes in surgically managed cases of lumbar spinal tuberculosis- A retrospective study

BACKGROUND

The advanced stage of vertebral involvement in spinal tuberculosis (STB) can cause vertebral body collapse, which leads to kyphotic deformity and paraplegia in severe cases. Surgery is indicated in patients having disabling back pain, progressive neurological deficit, and instability in spine despite conservative management. The derangement of lumbar parameters, especially the loss of lumbar lordosis has been found to cause functional deterioration in patients. With the current evidences in place, this study was done to evaluate the correlation between the restoration of lumbar lordosis, pelvic parameters, and functional outcome when posterior only approach was used to manage the lumbar STB.

METHODS

Active Tuberculosis of lumbar vertebra (L1-S1) confirmed by radiology (X-ray, MRI) and histopathological examination were included. All the cases scheduled for surgery underwent radiographs, CT scan, and MRI scans. Lumbar lordosis and other pelvic parameters were calculated on X-rays. VAS scores and ODI scores were documented during the follow-up to assess functional well-being.

RESULTS

A total of 33 (22 M:11 F) patients were included in the study. The mean lumbar lordosis pre-operatively was -22.84 ± 11.19° which was corrected to -37.03 ± 9.02° (p < 0.05) post-operatively. The pelvic tilt pre-operatively was 25.33 ± 6.75° which was corrected to 19.63 ± 5.84° (p < 0.05) post-operatively. The mean ODI improved from 84.33 ± 11.84 to 26.93 ± 8.74 (p < 0.05) at the final follow-up. The mean VAS score pre-operatively was 8.06 ± 1.27 which improved to 2.45 ± 0.93 (p < 0.05) in the post-operative period.

CONCLUSION

The study found a strong negative correlation between ODI scores and lumbar lordosis and a strong positive correlation between pelvic tilt and ODI scores. But the correlation needs to be further studied and evaluated by a well-constructed study especially with a control group treated conservatively.

Examination of Adult Spinal Deformity Patients Undergoing Surgery with Implanted Spinal Cord Stimulators and Intrathecal Pumps

STUDY DESIGN

Retrospective cohort study of a prospectively collected multi-center database of adult spinal deformity (ASD) patients.

OBJECTIVE

We hypothesized that patients undergoing ASD surgery with and without previous spinal cord stimulators (SCS)/ intrathecal medication pumps (ITP) would exhibit increased complication rates but comparable improvement in health-related quality of life.

SUMMARY OF BACKGROUND DATA

ASD patients sometimes seek pain management with SCS or ITP before spinal deformity correction. Few studies have examined outcomes in this patient population.

METHODS

Patients undergoing ASD surgery and eligible for 2-year follow-up were included. Preoperative radiographs were reviewed for the presence of SCS/ITP. Outcomes included complications, Oswestry Disability Index (ODI), Short Form-36 Mental Component Score, and SRS-22r. Propensity score matching was utilized.

RESULTS

In total, of 1034 eligible ASD patients, a propensity score-matched cohort of 60 patients (30 with SCS/ITP, 30 controls) was developed. SCS/ITP were removed intraoperatively in most patients (56.7%, n = 17). The overall complication rate was 80.0% versus 76.7% for SCS/ITP versus control (P > 0.2), with similarly nonsignificant differences for intraoperative and infection complications (all P > 0.2). ODI was significantly higher among patients with SCS/ITP at baseline (59.2 vs. 47.6, P = 0.0057) and at 2-year follow-up (44.4 vs. 27.7, P = 0.0295). The magnitude of improvement, however, did not significantly differ (P = 0.45). Similar results were observed for SRS-22r pain domain. Satisfaction did not differ between groups at either baseline or follow-up (P > 0.2). No significant difference was observed in the proportion of patients with SCS/ITP versus control reaching minimal clinically important difference in ODI (47.6% vs. 60.9%, P = 0.38). Narcotic usage was more common among patients with SCS/ITP at both baseline and follow-up (P < 0.05).

CONCLUSION

ASD patients undergoing surgery with SCS/ITP exhibited worse preoperative and postoperative ODI and SRS-22r pain domain; however, the mean improvement in outcome scores was not significantly different from patients without stimulators or pumps. No significant differences in complications were observed between patients with versus without SCS/ITP.Level of Evidence: 3.

Can Hip-Knee Line Angle Distinguish the Size of Pelvic Incidence?-Development of Quick Noninvasive Assessment Tool for Pelvic Incidence Classification

This study aimed to explore effective measurement angles for pelvic incidence (PI) classification and to develop a quick, noninvasive assessment tool for PI classification. We defined five variation types of hip–knee line (HKL) angles and tested the discrimination ability of the receiver operating characteristic (ROC) analysis using 125 photographs of upright standing posture from the right lateral side. ROC analysis revealed an applicable HKL angle defined by the line connecting the most raised part of the buttock and the central point of the knee and the midthigh line. The acceptable cut-off points for discriminating small or large PIs in terms of HKL angle were 18.5° for small PI (sensitivity, 0.91; specificity, 0.79) and 21.5° for large PI discrimination (sensitivity, 0.74; specificity, 0.72). In addition, we devised a quick noninvasive assessment tool for PI classification using the cut-offs of the HKL angle with a view to practical application. The results of intra- and inter-rater reliability ensured a substantial/moderate level of the tool (Cohen’s kappa coefficient, 0.79; Fleiss’s kappa coefficient, 0.50–0.54). These results revealed that the HKL angle can distinguish the size of the PI with a high/moderate discrimination ability. Furthermore, the tool indicated acceptable inter-/intra-rater reliability for practical applications.

Radiological Evaluation of Combined Anteroposterior Fusion with Vertebral Body Replacement Using a Minimally Invasive Lateral Approach for Osteoporotic Vertebral Fractures: Verification of Optimal Surgical Procedure

The combined anteroposterior fusion with vertebral body replacement (VBR) using a wide footplate expandable cage with a minimally invasive lateral approach has been widely used for pseudoarthrosis after osteoporotic vertebral fractures. The purpose of this study is to evaluate the radiological results of combined anteroposterior surgery using VBR and to recommend the optimal procedure. Thirty-eight elderly patients were included in this study. The mean preoperative local kyphosis angle was 29.3°, and the mean correction loss angle was 6.3°. Cage subsidence was observed in ten patients (26.3%), and UIV or LIV fracture in twelve patients (31.6%). Patients with cage subsidence were compared to those without cage subsidence to determine the causal factors. The mean number of fixed vertebrae was 5.4 vertebrae with cage subsidence and 7.4 vertebrae without cage subsidence. In addition, to precisely clarify the optimal number of fixed vertebrae, those patients with two above–two below fixation were compared to those with less than two above–two below fixation, which revealed that the correction loss angle was significantly less in two above–two below fixation (p = 0.016). Based on these results, we recommend at least two above–two below fixation with VBR to minimize the correction loss angle and prevent cage subsidence.

Current concepts in hip-spine relationships: making them practical for total hip arthroplasty

Hip, spine, and pelvis move in coordination with one another during activity, forming the lumbopelvic complex (LPC). These movements are characterized by the spinopelvic parameters sacral slope, pelvic tilt, and pelvic incidence, which define a patient's morphotype. LPC kinematics may be classified by various systems, the most comprehensive of which is the Bordeaux Classification. Hip-spine relationships in total hip arthroplasty (THA) may influence impingement, dislocation, and edge loading. Historical 'safe zones' may not apply to patients with impaired spinopelvic mobility; adjustment of cup inclination and version and stem version may be necessary to achieve functional orientation and avert complications. Stem design, bearing surface (including dual mobility), and head size are part of the armamentarium to treat abnormal hip-spine relationships. Special attention should be directed to patients with adult spine deformity or fused spine because they are at increased risk of complications after THA.

Correlation of Modic Changes with Sagittal Lumbopelvic Parameters

Purpose

The main aim of this retrospective study was to analyze lumbopelvic sagittal parameters among the three different types of Modic changes (MCs). Furthermore, correlations between the sizes of MCs and the number of involved lumbar levels with lumbopelvic parameters are investigated.

Methods

A total of 263 adult subjects with MCs at a single institution from September 2015 to October 2020 who underwent lumbar x-ray examinations and magnetic resonance imaging were included in this retrospective study. Types of MCs, sizes of MCs, lumbar levels involved by MCs as well as lumbopelvic sagittal parameters from each subject were evaluated by two authors.

Results

Lumbar lordosis (LL), sacral slope (SS), and pelvic incidence (PI) in subjects with MC grade 1 were significantly smaller than in those with MC grade 2 and grade 3 (p<0.05). Lumbopelvic sagittal parameters decreased significantly as the sizes aggravated (p<0.01). Triple lumbar levels with MCs showed a significant increase in PI-LL (p<0.05) and decrease in LL (p<0.01), SS (p<0.01), and PI (p<0.01) when compared to MCs at single and double lumbar levels.

Conclusion

MC grade 1, severe MCs, and lumbar multi-segmental MCs were significantly linked to lumbar sagittal imbalance.

Gravity center estimation for evaluation of standing whole body compensation using virtual barycentremetry based on biplanar slot-scanning stereoradiography - validation by simultaneous force plate measurement

Background

Whole body standing alignment (WBSA) in terms of biomechanics can be evaluated accurately only by referring the gravity line (GL) which lies on the gravity center (GC). Here, we introduce a method for estimating GL and simultaneous WBSA measurement using the EOS® imaging system and report on the reproducibility and reliability of the method.

Methods

A 3-dimensional (3D) avatar to estimate GC was created following three steps: 3D reconstruction of the bone based on EOS images; deformation into a generic morphotype (MakeHuman statistical model) before density integration with 3D rasterization of the full body into 1-mm³ voxels (the content of each voxel is considered homogeneous); computation of the density of all the voxels provides the center of mass, which can be projected onto the floor as the GC of the full body, providing the GL in relation to the WBSA. The repeatability, reproducibility, and accuracy of the estimated GC and body weight of the avatar were compared with clinical estimation using a force plate in healthy volunteers and patients with degenerative and deformative diseases.

Results

Statistical analyses of the data revealed that the repeatability and reproducibility of the estimation was high with intra-rater and inter-rater intraclass correlation coefficient. ≥0.999. The coordinate values of the GC and body weight estimation did not differ significantly between the avatar and force plate measurements, demonstrating the high accuracy of the method.

Conclusion

This new method of estimating GC and WBSA is reliable and accurate. Application of this method could allow clinicians to quickly and qualitatively evaluate WBSA with GL with various spinal malalignment pathologies.

Evolution of Complex Spine Surgery in Neurosurgery: From Big to Minimally Invasive Surgery for the Treatment of Spinal Deformity

Spinal instrumentation for adult spinal deformity dates back to the surgical correction of secondary complications from infectious processes, such as Pott's disease and poliomyelitis [1]. With the population aging at a longer life expectancy today, advanced degenerative spinal diseases and idiopathic scoliosis supersede as the most common causes of adult spinal deformity. Correction of the thoracolumbar malignment, specifically, has rapidly evolved with the burgeoning success of spinal instrumentation. The objective of this chapter is to review the metamorphosis of operative principles for adult thoracolumbar deformity, from aggressive osteotomies in the posterior bony elements to minimally invasive surgery (MIS) at the intervertebral disc space.

Predictive formulae of ideal lumbar lordosis determined by individual pelvic incidence and thoracic kyphosis in asymptomatic adults

BACKGROUND

The precise prediction of ideal lumbar lordosis (LL) has become increasingly important in clinical practice. The aim of this study was to explore the regulatory mechanisms of sagittal spinopelvic alignment and to predict ideal LL based on individual pelvic incidence (PI) and thoracic kyphosis (TK) parameters in asymptomatic adults.

METHODS

A total of 233 asymptomatic subjects older than 18 years were consecutively enrolled in our study between April 2017 and December 2019. A full-spine, standing X-ray was performed for each subject. The following parameters were measured in the sagittal plane: the apex of lumbar lordosis (LLA), the distance between the plumb line of the lumbar apex (LAPL) and the gravity plumb line, the inflection point (IP), LL, the upper arc and lower arc of lumbar lordosis (LLUA and LLLA, respectively), PI and TK. Stepwise multiple linear regressions were conducted, and the statistical significance level was P < 0.05.

RESULTS

Both PI and TK were two important predictive variables for LLA, LAPL, IP and LL. In addition, the LLUA was mainly explained by TK, while the LLLA was explained by PI. The corresponding predictive models are listed as follows: LLA = 17.110 - 0.040∗PI + 0.023∗TK (R² = 0.380), LAPL = 31.296 + 0.467∗PI - 0.126∗TK (R² = 0.309), IP = 10.437 + 0.091∗TK - 0.029∗PI (R² = 0.227), LL = 2.035 + 0.618∗PI + 0.430∗TK (R² = 0.595), LLUA = 0.893 + 0.418∗TK (R² = 0.598), LLLA = 3.543 + 0.576∗PI (R² = 0.433).

CONCLUSION

The specific sagittal lumbar profile should be regulated by both pelvic and thoracic morphology. Such predictive models for lumbar parameters determined by individual PI and TK parameters have been established, which are meaningful for surgeons to better understand the regulatory mechanisms of sagittal spinopelvic alignment and reconstruct a satisfactory lumbar alignment.

SPINOPELVIC PARAMETERS AFTER POSTERIOR LUMBAR ARTHRODESIS IN DEGENERATIVE SPINAL DISEASES

ABSTRACT Introduction: Spinopelvic parameters related to sagittal balance have become increasinglyimportantamong spine surgeons due to their correlation with patient satisfaction rates. Objective: The goal of this study was to evaluate changes in spinal sagittal balance after lumbar spine surgery using PLIF, the posterior lumbar interbody fusion technique. Methods: The sample consisted of adult patients with degenerative spinal disease submitted to posterior lumbar arthrodesis. Patients between 18 and 70 years of agewho underwent surgeryfrom 2015 to 2017 were included in the study and divided into short (1 level) and long arthrodesis (2 to 4 levels) groups. Radiographic analysis of the spinopelvic parameters, measured before and after lumbar arthrodesis, was conducted using the SURGIMAP software. Then we evaluated the variation between pre- and postoperative measurements and performed correlation and linear regression analyses between the parameters. Results: The sample was composed of 80 patients (48 men). The mean age was lower in the short arthrodesis group than in the long arthrodesis group (52.67 ± 9.66 years versus 59.37 ± 9.30 years, respectively; p<0.0025). Significant variations in lumbar lordosis, pelvic tilt, sagittal vertical axis, T1 pelvic angle, and pelvic incidence minus lumbar lordosis were found in both short and long arthrodesis groups. The variation was significantly larger in the long than in the short arthrodesis group. Conclusion: In adult degenerative spine disease, short and long arthrodesis of the lumbar spine by PLIF allows correction of the spinopelvic parameters. Level of evidence III; Retrospective, comparative study.

Upper instrumented vertebra-femoral angle and correlation with proximal junctional kyphosis in adult spinal deformity

INTRODUCTION

Although matching lumbar lordosis (LL) with pelvic incidence (PI) is an important surgical goal for adult spinal deformity (ASD), there is concern that overcorrection may lead to proximal junctional kyphosis (PJK). We introduce the upper instrumented vertebra-femoral angle (UIVFA) as a measure of appropriate postoperative position in the setting of lower thoracic to pelvis surgical correction for patients with sagittal imbalance. We hypothesize that a more posterior UIV position in relation to the center of the femoral head is associated with an increased risk of PJK given compensatory hyperkyphosis above the UIV.

METHODS

In this retrospective cohort study, adult patients undergoing lower thoracic (T9-T12) to pelvis correction of ASD with a minimum of 2-year follow-up were included. UIVFA was measured as the angle subtended by a line from the UIV centroid to the femoral head center to the vertical axis. Patients who developed PJK and those who did not were compared with preoperative and postoperative UIVFA as well as change between postoperative and preoperative UIVFA (deltaUIVFA).

RESULTS

Of 119 patients included with an average 3.6-year follow-up, 51 (42.9%) had PJK and 24 (20.2%) had PJF. Patients with PJK had significantly higher postoperative UIVFA (12.6 ± 4.8° vs. 9.4 ± 6.6°, p = 0.04), deltaUIVFA (6.1 ± 7.6° vs. 2.1 ± 5.6°, p < 0.01), postoperative pelvic tilt (27.3 ± 9.2 vs. 23.3 ± 11, p = 0.04), postoperative lumbar lordosis (47.7 ± 13.9° vs. 42.4 ± 13.1, p = 0.04) and postoperative thoracic kyphosis (44.9 ± 13.2 vs. 31.6 ± 18.8) than patients without PJK. With multivariate logistic regression, postoperative UIVFA and deltaUIVFA were found to be independent risk factors for PJK (p < 0.05). DeltaUIVFA was found to be an independent risk factor for PJF (p < 0.05). A receiver operating characteristic (ROC) curve for UIVFA as a predictor for PJK was established with an area under the curve of 0.67 (95% CI 0.59-0.76). Per the Youden index, the optimal UIVFA cut-off value is 11.5 degrees.

CONCLUSION

The more posterior the UIV is from the femoral head center after lower thoracic to pelvis surgical correction for ASD, the more patients are at risk for PJK. The greater the magnitude of posterior translation of the UIV from the femoral head center from preop to postop, the greater the likelihood for PJF.

ANATOMIC AND FUNCTIONAL ANALYSIS OF THORACIC KYPHOSIS AND LUMBAR LORDOSIS

ABSTRACT Objective: Rate and compare radiographic measurements of thoracic kyphosis and lumbar lordosis using anatomical and dynamic parameters. Methods: Measurements were performed on lateral radiographs of 10 adults of both sexes without spinal disease or deformity. Thoracic kyphosis and lumbar lordosis were measured using anatomical parameters (T1-T12, T4-T12, T5-T12 and L1-S1) or dynamic parameters (cervicothoracic or thoracolumbar inflection point). Results: Thoracic kyphosis and lumbar lordosis were different in 30% of subjects. Differences in thoracic kyphosis values were observed according to the anatomical reference used for measurement. Lumbar lordosis wasn`t statistical difference considering the anatomical or dynamic reference, but in 30% of the individuals the inflection point was different from the anatomical reference. Conclusions: Thoracic kyphosis and lumbar lordosis values differ according to anatomical and dynamic references. The reference used must be considered in the measurement and interpretation of values. Level of evidence IV; Case series.