Adult spinal deformity-postoperative standing imbalance: how much can you tolerate? An overview of key parameters in assessing alignment and planning corrective surgery

Motion analysis in adult spinal deformity: A time-driven activity-based costing perspective

BACKGROUND

A novel motion analysis (MA) protocol for patients with adult spinal deformity (ASD) was developed within University Hospitals Leuven, aiming for better functional outcomes by improved treatment planning and decision making.

RESEARCH QUESTION

Can insights into the costs of a research-focused MA (RMA) protocol support the transition to a concise clinical MA (CMA) protocol and facilitate its potential adoption as standard clinical care?

METHODS

Time-driven activity-based costing (TD-ABC) was used to quantify the costs directly related to performing the MA protocol. Time durations were derived from observations and interviews and validated using time intervals retrospectively derived from previous motion analyses metadata. Costs were computed based on resource time usage and the per-minute cost of practical capacity. An expert panel then refined the RMA into a CMA protocol by excluding some trials, utilizing cost insights and insights in the potential clinical relevance of trials, including their discriminative abilities, their ability to highlight compensatory mechanisms and their standardization potential. The clinical costs of the CMA were then again calculated using the same methodology.

RESULTS

The average time to perform the RMA was 179.0 minutes and dropped to 130.9 minutes after the expert panel excluded 12 types of motion trials. The total cost of this new CMA was € 220.83. The largest cost component of the CMA was staff costs (68.1 %), followed by the cost of equipment (30.2 %).

SIGNIFICANCE

This study demonstrates how cost insights complement insights on clinical relevance when defining a motion analysis protocol for integration in standard clinical care. Future value- improvements to the protocol should also integrate insights on its impact on treatment outcome.

Ideal Lumbar Lordosis Correction in Patients With Adult Spinal Deformity Without Adversely Impacting Pelvic Tilt and Pelvic Incidence Minus Lumbar Lordosis: A Study of 426 Cases

STUDY DESIGN

Retrospective study.

OBJECTIVES

To determine the ideal pelvic incidence (PI)-lumbar lordosis (LL) range to prevent pelvic tilt (PT) undercorrection while avoiding PI-LL overcorrection following adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND

PI-LL and PT are the important sagittal parameters to be restored to an adequate range by surgery. Ideal PI-LL target without causing PI-LL overcorrection and PT undercorrection has not been documented.

METHODS

We included patients with ASD undergoing ≥5-level fusion, including the sacrum. Receiver operating characteristic (ROC) curve analysis was performed to calculate the lower limit of the ideal PI-LL without causing PI-LL overcorrection and the upper limit of the ideal PI-LL without causing PT undercorrection. The calculated ideal PI-LL was validated in terms of proximal junctional kyphosis and failure (PJK and PJF) rates and clinical outcomes. Analyses were performed according to age subgroups (below 70 and 70 yr or above).

RESULTS

In total, 426 patients were included in the study. Female patients were predominant (85.4%), with a mean age of 69.8 years. The lower limits of PI-LL were calculated as 4.9° for all patients, 2.3° for patients aged below 70 years, and 7.9° for patients aged 70 years or above. Meanwhile, the upper limits of PI-LL were calculated as 12.7° for all patients, 12.5° for patients aged below 70 years, and 13.3° for patients aged 70 years or above. There were no significant differences in the PJK and PJF rates among the new three PI-LL groups. Clinical outcomes were significantly better in patients with the ideal PI-LL group than those in patients with overcorrection or undercorrection groups for all age groups.

CONCLUSIONS

The ideal PI-LL correction target without adversely impacting PT and PI-LL was calculated at 2.3° to 12.5° for patients aged below 70 years and 7.9° to 13.3° for patients aged 70 years or above. These guideline parameters may help ensure optimal clinical outcomes without increasing the risk of PJK/F.

Evaluation of Discrepancy Between Radiographic Success and Patient Satisfaction in Adult Spinal Deformity Surgery

BACKGROUND AND OBJECTIVES

Considering the high surgical invasiveness of adult spinal deformity surgery, patient-perceived satisfaction may not necessarily follow good radiographic results. This study investigated the incidence and risk factors for the discrepancy between radiographic success and patient satisfaction after adult spinal deformity surgery.

METHODS

We retrospectively analyzed 195 patients (mean age, 68.3 years) who underwent ≥4 level fusion surgery including the pelvis and achieved radiographic success as assessed by surgeons (that is, optimal alignment, no mechanical complications, and no revision surgery). The patients were divided into two groups according to Scoliosis Research Society (SRS)-22 satisfaction scores: less satisfied (score <4.0) and highly satisfied (score ≥4.0) groups. Preoperative and postoperative 2-year clinical and radiographic variables were analyzed to predict the lower satisfaction.

RESULTS

The clinical outcomes, including visual analogue scale, SRS-22, and Shor Form (SF)-36, significantly improved postoperatively, while modified lumbar stiffness disability index (M-LSDI) significantly worsened postoperatively. In bivariate comparisons, the total fusion length was significantly greater in the less satisfied group than in the highly satisfied group (6.9 vs 6.1). Preoperative and 2-year postoperative radiographic parameters were comparable between the groups. The preoperative SF-36 mental component score, 2-year visual analogue scale, 2-year Oswestry disability index, 2-year SRS-22, 2-year SF-36, and 2-year M-LSDI scores were significantly worse in the less satisfied group than in the highly satisfied group. The multivariate regression analysis revealed that the 2-year M-LSDI score was a single independent risk factor for less satisfaction (odds ratio = 1.290, 95% CI = 1.032-1.611, P = .025).

CONCLUSION

A sizable proportion (24.1%) of patients were dissatisfied with the surgical outcomes despite satisfactory radiographic results. Although the patients benefited from surgery for pain and functional improvement, postoperative lumbar stiffness-related functional disabilities adversely affected patient satisfaction. Therefore, before deciding on surgical treatment, patients should be fully informed of this trade-off between pain/disability and lumbar stiffness.

Assessment of lumbosacral spinal curvatures before and after surgery using 3D posturography

Open discectomy remains the standard procedure for decompressing neural structures in cases of intervertebral disc herniation. Early postoperative rehabilitation emphasizes protecting the surgical site while restoring functional independence in daily activities. In the absence of possibilities for performing any spinal control tests within the first few days post-surgery, the dynamism of curvature changes may be the sole criterion for evaluating rehabilitation progress. This study aims to evaluate the feasibility of utilizing the non-invasive KINEOD device to measure the dynamics of lumbosacral spinal alignment parameters in the sagittal plane before and immediately after surgical intervention. The study involved 30 patients (14 women [46.67%] and 16 men [53.33%]) from the Neurosurgical Department of the Wojewódzki Szpital Specjalistyczny in Słupsk, Poland. Data were collected using a custom questionnaire and KINEOD 3D posturography to assess body posture. The following parameters were analyzed: Sagittal Inclination Angle (Sagittal IA), Kyphosis Angle (KA), Lordosis Angle (LA), Sacral Inclination Angle (Sacral IA), Lordosis Measure (LM), Inflection Point (IP), and the Angle of Acromion-Posterior Superior Iliac Spine Rotation (A-PSIS). Measurements were conducted at three stages: Stage I - one day before surgery (2:00 PM); Stage II - on the third postoperative day (7:00 AM); and Stage III - on the third postoperative day (2:00 PM). Measurements utilizing the KINEOD device revealed statistically significant changes between Stage I and Stage II for the following parameters: Sagittal IA, KA, LA, Sacral IA, LM, IP, and A-PSIS. Significant changes were also noted between Stage I and Stage III for KA, LA, Sacral IA, LM, A-PSIS, and VAS. The study highlights that the reliability of KINEOD 3D assessment diminishes when relying solely on parameters such as Sacral IA and IP for postoperative lordosis evaluation. For rapid, non-invasive assessment of the lumbosacral spine post-surgery, Sacral IA may serve as a more accurate indicator of dynamic changes in the lower lumbar region. Postoperative alterations in all sagittal plane angles are influenced by both surgical intervention and, to a lesser extent, the diurnal adaptation rhythm.

Comparing Spinopelvic Angles and Magnification on Supine MRI With Standing Radiographs in Lumbar Spinal Stenosis

STUDY DESIGN

Radiologic cross-sectional study based on a prospective cohort study (level III).

OBJECTIVE

Investigate whether lumbar lordosis (LL) and sacral slope (SS) differ significantly on supine magnetic resonance imaging (MRI) versus standing radiographs in nondeformity lumbar spinal stenosis (LSS). Secondly, to quantify the amount of magnification on standing lumbar radiographs.

SUMMARY OF BACKGROUND DATA

Supine MRI is routinely performed when diagnosing LSS. Standing radiographs are often supplemented to measure spinopelvic angles. Little research has been done on whether LL and SS translate from standing radiographs to supine MRI. Previous studies have trended to significant changes in LL and SS; however, none have been performed exclusively in nondeformity LSS.

MATERIALS AND METHODS

Review of preoperative standing lateral lumbar radiographs and midsagittal T2-weighted supine lumbar MRI in 211 patients with LSS without concomitant degenerative spondylolisthesis, measuring LL (L1-S1), segmental lumbar lordosis (sLL) (L4-S1) and SS, in addition to the anteroposterior diameter and height of the L3 vertebral body. We conducted a reliability study and performed a Pearson's correlation analysis. Data was presented in Bland-Altman plots.

RESULTS

Interobserver reliability was good to excellent, with ICC ranging from 0.77 to 0.94 for all parameters. Statistically significant differences were observed in LL and SS between image modalities. The mean radiographic measurements were as follows: LL 48.9 (SD: 12.8), sLL 32.3 (SD: 8.1), and SS 37.3 (SD: 8.7) degrees. The mean MRI measurements were as follows: LL 46.0 (SD: 10.5), sLL 32.3 (SD: 7.1), and SS 38.1 (SD: 7.1) degrees. Mean vertebral body magnification was between 21% and 23% for L3 anteroposterior diameter and height.

CONCLUSIONS

Our results suggest that supine lumbar MRI might be a viable alternative to standing lateral lumbar radiographs for measuring LL and SS in routine follow-up for patients with LSS without concomitant spinal deformity. Standing radiographs are recommended as part of the initial investigation for LSS. Standing lumbar radiographs may yield high grades of magnification.

Impact of spinal alignment on adjacent segment disease and degeneration after short-segment lumbosacral fusion

BACKGROUND CONTEXT

Adjacent segment disease (ASDis) and degeneration (ASDeg) are common complications following lumbar fusion, ranging from asymptomatic radiographic changes to debilitating symptoms requiring revision surgery. While the impact of spinopelvic alignment (SPA) on postoperative outcomes and ASDis prevention is well-studied in long-construct fusions, its role in short-segment lumbosacral fusions, particularly over the long term, remains unclear.

OBJECTIVE

This study aimed to investigate the association between global and distal lumbar SPA with the development of ASDis and ASDeg in the long-term follow-up of patients undergoing short-segment lumbosacral fusion. Secondary outcomes were patient reported outcome measures (PROMs) in relation to adjacent segment changes.

STUDY DESIGN/SETTING

Retrospective single-center cohort study with minimum follow-up of 5 years.

PATIENT SAMPLE

A total of 86 patients who underwent L4-S1 spinal fusion between 2003 and 2015, with a mean follow-up of 12±4 years.

OUTCOME MEASURES

The primary outcome was the development of adjacent segment changes, classified into 2 groups: (1) surgically-treated ASDis, and (2) ASDeg, defined as radiographic evidence of adjacent segment changes without surgical intervention. Secondary outcomes included PROMs: the Oswestry Disability Index (ODI) and the European Quality of Life 5 Dimensions 5 Level (EQ5D5L).

METHODS

Pre- and postoperative standing radiographs were annotated and the following global lumbar SPA parameters analyzed: Pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis (LL), PI-LL-mismatch, lumbar pelvic angle (LPA). Additionally, the following distal lumbar SPA parameters were analyzed: Distal lordosis (DL) between L4-S1, lordosis distribution index (LDI=DL/LL), PI-DL-difference, DL-PI-ratio, adjacent segment lordosis (ASL). Postoperative ODI and EQ5D5L were assessed via a telephone interview.

RESULTS

Among 86 patients with a mean follow-up of 12±4 years the incidence of ASDis was 27.9% (n=24), while 7.0% (n=6) showed ASDeg. No significant differences in pre- and postoperative global lumbar SPA were found in patients who developed ASDis or ASDeg compared to patients who did not. PI (53.6° vs. 59.6°) and preoperative SS (34.9° vs. 40.3°) trended to be lower in the ASDis group compared to controls, although non-significant. Pre- and postoperative distal lumbar SPA parameters did not differ between groups. Patients with adjacent segment changes, regardless of whether they underwent revision surgery, reported worse PROMs. ODI scores were elevated in both the ASDis group (28, IQR 15-42) and the ASDeg group (34, IQR 14-47) compared to controls (10, IQR 2-24; p=.005). EQ5D5L scores were lower in both the ASDis (70, IQR 53-83) and the ASDeg groups (60, IQR 55-85) compared to controls (85, IQR 75-90; p=.025).

CONCLUSION

In this long-term follow-up study of patients undergoing short-segment lumbosacral fusion, neither preoperative nor postoperative SPA was significantly associated with the development of ASDis or ASDeg. These findings suggest that other factors may have a greater influence on ASDis risk. Patients who developed adjacent segment changes, whether or not they required revision surgery, experienced worse long-term postoperative PROMs, indicating the importance of ASDis prevention.

Analyzing the L4-5 Segmental Alignment Change of Two Minimally Invasive Prone-Based Interbody Fusions

Study DesignRetrospective Cohort Study.ObjectiveRestoration of lumbar lordosis (LL) is a principal objective during spinal fusion procedures, traditionally focusing on achieving an LL within 10° of the pelvic incidence (PI). Recent studies have demonstrated a relatively constant L4-S1 alignment of 35-40° at L4-S1 and at least 15° at L4-5, regardless of PI. Based on these results, this study was created to examine the success rate of achieving a minimum of 15° at L4-5 through two differing prone-based techniques: Prone Lateral (pLLIF) and Trans Foraminal Interbody Fusion (TLIF).MethodsOne hundred patients with a primary single-level L4-5 interbody fusion (50 pLLIF and 50 TLIF) were retrospectively analyzed. Pre and post-operative radiographs were measured to examine the segmental change at each level in the lumbar spine and calculate the success rate for achieving a minimum L4-5 segmental lordosis of 15° at the final follow-up.ResultsThe overall success rate of achieving an L4-5 segmental alignment >15° at the final follow-up was 70%. Prone LLIF was significantly more likely than TLIF to achieve this goal, achieving L4-5 > 15° 84% of the time vs TLIFs 56% (P = 0.002). Prone LLIF demonstrated an average L4-5 increase of 5.6 ± 5.9° which was larger than the mean increase for TLIF 0.4 ± 3.8° (P < 0.001). In both techniques, there was an inverse correlation between pre-operative L4-5 angle and L4-5 angle change.ConclusionProne lateral lumbar interbody fusion demonstrates a high success rate for achieving a post-operative L4-5 angle >15° and achieves this at a higher rate than TLIF.

Radiographic Alignment Parameters for Lumbosacral Reconstruction in Patients With Altered S1 Morphology

Study DesignRetrospective quantitative analysis study.ObjectivesPelvic incidence has been established as central radiographic marker which determines patient-specific correction goals during surgery for adult spinal deformity. In cases with sacral doming or sacral osteotomy where the PI cannot be calculated, reliable radiographic parameters need to be established to determine surgical goals. We aim to determine multiple radiographic parameters and formulas that can be utilized when the S1 superior endplate is obscured.MethodsRetrospective analysis was performed on 68 healthy volunteers without prior spine surgery with full-length radiographs. Pelvic incidence, sacral slope, and pelvic tilt were calculated for each patient. Additional measurements such as L4, L5, and S2 incidence, tilt, and slope were collected. A new radiographic parameter defined as the L4-Sciatic notch angle was measured. Regression analysis was performed on each value to determine its relationship with S1 based incidence, tilt, and slope.ResultsMean values for L5 incidence, L4 incidence, and L4 sciatic notch angle were 21.8° ± 8.9, 4.4° ± 8.1, and 44.4° ± 12, respectively. The linear regression analysis produced the following formulas which can be utilized to determine deformity correction goals when pelvic incidence can be calculated pre-operatively: L5i = .65*S1i-11.4, L4i = .44*S1i-18.6, and L4SNA = -.34*S1i + 66.5. In settings where pelvic incidence cannot be calculated, the following formulas can be utilized: L5i = .66*S2i-32.3 and L4SNA = -.02*S2i2 + 1.1*S2i + 63.5. P-values for all regression analyses were <.001.ConclusionThis study provides target radiographic alignment values that can be utilized for patients with either pre-operative altered S1 endplates or in cases with intraoperative alteration of S1 (sacral osteotomy).

Influence of decompression surgery on sagittal balance parameters in patients with lumbar spinal stenosis

In this study we investigated the effect that lumbar decompression for lumbar spinal stenosis (LSS) has on sagittal balance and its clinical significance. This was an observational cohort study for LSS cases treated with decompression surgery. Core Outcome Measures Index (COMI), EuroQoL (EQ-5D) and Oswestry Disability Index (ODI) were used preoperatively and at 1 year follow-up. Pelvic incidence (PI), pelvic tilt (PT), sagittal vertical axis (SVA) and lumbar lordosis (LL) were measured before and 1 year after surgery. Hierarchical clustering (HC) was performed to identify subgroups with distinct patterns of variation. Ninety-five patients were included, mean age of 63 years, with good/excellent outcome in 71.6%. The median difference between postoperative and preoperative LL was - 1.3o. Increased lumbar lordosis was correlated to ODI improvement (Pearson, r=-0.33). Three clusters were identified after HC. Patients in cluster 2 (31.6% ) had decrease in LL after surgery (mean values for cluster 1, 2, 3: 3.3o, -5.6o, 0.8o), increase in SVA (-5 mm, + 25 mm, -19 mm) and no improvement in ODI (-23.1, 3.77, -17.1). Lumbar decompression has little effect in lumbar lordosis and sagittal balance. Cluster analysis yielded a subgroup of patients with worse outcomes, associated to decrease of LL and increase of SVA after surgery.

Pelvic Incidence as a Predictor of Proximal Junctional Kyphosis in Patients With Lenke Type 5 Adolescent Idiopathic Scoliosis

STUDY DESIGN

A retrospective comparative study.

OBJECTIVE

The purpose of this study is to evaluate the relationship between pelvic incidence (PI) and proximal junctional kyphosis (PJK) in patients with Lenke type 5 adolescent idiopathic scoliosis (AIS).

BACKGROUND

Although PJK is a common complication of sagittal malalignment after posterior correction and fusion surgery (PSF), few studies have assessed its risk factors. The significance of pelvic morphology in relation to PJK has been suggested but remains unclear in Lenke type 5 AIS patients.

MATERIALS AND METHODS

A total of 92 patients with Lenke type 5 AIS who underwent selective thoracolumbar PSF with a minimum follow-up of two years were included. Patients were divided into PJK and non-PJK groups based on postoperative radiographs. The influence of PI on PJK occurrence was evaluated through binary logistic analysis. Subgroup analysis was performed based on the PI value (low PI, <45°; high PI, ≥ 45°) to identify factors affecting PJK occurrence.

RESULTS

PJK was observed in 17.4% of the whole cohort. Binary logistic regression analysis identified low PI and large TL/L curve as a risk factor for PJK (PI, odds ratio, 0.933; TL/L curve, odds ratio, 1.080). Subgroup analysis showed that the postoperative increase in the upper instrumented vertebra slope in PJK cases was comparable in both the low and high PI groups. Meanwhile, lordotic changes in the fused area in the PJK cases were observed only in the low PI group. No difference in the Scoliosis Research Society 22 scores was observed between the two groups.

CONCLUSION

From this study a low PI was identified as a risk factor for the occurrence of PJK in Lenke type 5 AIS patients. The occurrence of PJK is influenced by lordotic changes in the fused area and the limited compensatory capacity of the pelvis in patients with a low PI.

Corrective Long Spinal Fusion to the Ilium for Patients with Adult Spinal Deformity Results in Good Physical Function after Mid- to Long-Term Postoperative Follow-Up

Introduction

This study investigated the mid- to long-term postoperative outcomes of patients with adult spinal deformity (ASD), focusing on physical function and quality of life (QOL). We also compared age-related changes between patients aged 75 years or older (high elderly) and those younger than 75 years (low elderly).

Methods

A total of 47 patients with ASD underwent thoracic-iliac long spinal fusion between August 2013 and September 2014. The study spanned from the preoperative period to at least 5 years postoperatively. Physical function was assessed using isometric hip flexion and knee extension muscle strength, the 6-min walk distance test, the 10-m walk test, and the timed up and go test. QOL was assessed using the Scoliosis Research Society-22 and Oswestry Disability Index. Repeated-measures analysis of variance with a mixed model approach, corrected for multiple comparisons using Bonferroni, was performed.

Results

Of the 47 patients, 21 participated in the study. Patients with ASD showed improved gait ability postoperatively. Hip flexor strength decreased at more than 5 years postoperatively compared with the preoperative strength. Patient-reported outcome (PRO) scores showed continuous improvement postoperatively, regardless of age. Although older patients had lower preoperative and postoperative physical function, their PRO scores significantly improved and remained favorable for more than 5 years postoperatively.

Conclusions

Patients with ASD experienced sustained improvements in walking ability and PRO for more than 5 years postoperatively. The results of this study showed that even among the elderly, PRO scores consistently improved after surgery and remained positive for an extended period.

How to Reduce the Risk of Mechanical Failures in Adult Deformity Surgery: Comparing GAP Score and Roussouly Type Restoration

Study DesignRetrospective Cohort Study.ObjectivesTo assess long-term alignment descriptors correlating with mechanical complications.MethodsThe study included adult spinal deformity cases older than 18, with a minimum of four instrumented levels and a 5-year follow-up. Exclusions: previous spinal fusion, neuromuscular/rheumatic diseases, active infections, tumors, or incomplete radiographic exams. Collected data: demographic, surgical, pre- and post-operative spinopelvic parameters, and post-operative complications. The GAP score, original Roussouly type restoration, Schwab's criteria, and Odontoid to hip axis angle were evaluated using machine learning and logistic regression. Complications were evaluated with a Kaplan-Meier curve.ResultsTwo hundred and twelve patients fulfilled the inclusion and exclusion criteria and were enrolled in the study. The observed rate of revision surgery for mechanical complications was 40.6% (86 out of 212 patients). Higher post-operative GAP scores were associated with increased risks of revision for junctional failure (AUC = 0.72 [IC 95%] 0.62-0.80). The inability to restore the original Roussouly spinal shape was statistically associated with higher mechanical failure rates. A machine-learning approach and subsequent logistic regression found that the GAP score and original Roussouly type restoration are the most important predictors for mechanical failure, and GAP score lordosis distribution index and relative pelvic version are the most important factors to predict the risk of mechanical failure.ConclusionsIn our series, a proper post-operative GAP Score and the restoration of the original Roussouly type significantly minimize mechanical complication rates. We observed that junctional failure tends to occur earlier among complications, while implant failure occurs later in the follow-up.

An update on improvement and innovation in the management of adult thoracolumbar spinal deformity

Adult spinal deformity (ASD) is a spectrum of abnormalities of the thoracic and lumbar spine and has an increasing prevalence. It is associated with significant physical and mental disability in symptomatic patients. Given the increased rates and the morbidity associated with this disease, novel innovation in the diagnosis and treatment of such deformity is required. The SRS-Schwab classification system described coronal scoliotic deformity with sagittal modifiers. Other parameters, such as the sagittal vertical axis, pelvic tilt, T1 pelvic angle, pelvic incidence and lumbar lordosis attempted to quantify global sagittal balance. More recently, a focus on more patient specific parameters has been targeted to improve patient outcomes. The Roussouly classification system attempted to predict sagittal alignment parameters based on fixed parameters of the pelvis. Others determined the parameters based on patient age. Technological advances have also enhanced our understanding of ASD. Long cassette films and automated analyses have allowed standardization of these measurements across physicians. 3D printing has been used as an adjunct for both surgical planning and implants, both generic and patient specific, to improve outcomes. With these, advances in minimally invasive approaches have allowed ASD correction with lower complications and blood loss. Intraoperative navigation and the use of robotics has allowed improved accuracy in the care of these patients. Development of complex osteotomies have allowed for correction of advanced deformity. Fusion, however, is the ultimate goal of surgical ASD correction. Advances in biologics such as the use of recombinant Human Bone Morphogenetic Protein-2 have been used to improve fusion rates and combat pseudoarthrosis. Finally, post-operative advances in ASD patient care with emphasis on enhanced recovery after surgery has allowed improvements in hospital length of stay and pain scores. ASD is becoming a more ubiquitous diagnosis for spine surgeons with an increasing aging population. Improvement in the understanding of the diagnosis, spinopelvic parameters, imaging techniques, and post operative care are all aimed toward helping patients in whom care can be extremely difficult. Further study in ASD patient care will target advanced innovation to provide optimal treatment to these patients and allow for best possible outcomes.

Does Adherence to Treatment Guidelines from the Ghailane-Gille Classification for Degenerative Spondylolisthesis of the Lumbar Spine Impact Surgical Outcomes? A Match-Mismatch Study

Background/Objectives: satisfactory sagittal alignment when treating degenerative spondylolisthesis of the lumbar spine (DSLS) may produce better clinical and radiographic outcomes compared to treatment focused solely on isolated segments when indicated. Ghailane et al. proposed a treatment guideline based on their classification system. The aim of this study was to investigate the impact of adherence to Ghailane-Gille (GG) treatment guidelines on surgical outcomes in patients with DSLS. Methods: A monocentric retrospective cohort analysis was performed from 2021 to September 2024. Data were collected from patients treated for DSLS, covering the period from baseline to one-year follow-up. Patients were divided into two groups based on GG treatment guidelines: the "Match group" (patients who underwent surgery following GG guidelines) and the "Mismatch group" (patients who did not adhere to these guidelines). Preoperative and postoperative clinical outcomes, patient satisfaction, and operative parameters were collected and compared between groups. Results: A total of 80 patients were enrolled, with 52 in the Match group and 28 in the Mismatch group. At baseline, the Oswestry Disability Index (ODI) score demonstrated significant variation among classification subtypes and a positive correlation. The Match group exhibited a significant reduction in ODI scores one year postoperatively and maintained high levels of satisfaction; no significant intraoperative differences were noted. Additionally, patients in the Mismatch group were more frequently classified as American Society of Anesthesiologists (ASA) III compared to the Match group (70% vs. 30%), suggesting clinicians' hesitance to fully implement GG guidelines in aggressive treatment strategies for those patients. Conclusions: Adhering to the GG treatment guidelines for restoring sagittal alignment in DSLS patients is associated with decreased ODI scores regardless of age, ensuring patient satisfaction at one-year follow-up. This approach could potentially benefit ASA III patients as well.

Are Surgical Outcomes Different According to Baseline Balance Status in Elderly Patients with Degenerative Sagittal Imbalance?

STUDY DESIGN

This is a retrospective study.

OBJECTIVE

We sought to compare surgical outcomes according to baseline balance statuses in elderly patients with degenerative sagittal imbalance (DSI).

SUMMARY OF BACKGROUND

Although optimal sagittal correction has been emphasized for good surgical outcomes, the effect of the state of preoperative balance on surgical outcomes has been adequately described at present.

METHODS

Patients aged 60 years and above with DSI who underwent ≥5-level fusion to the sacrum were included. Among them, only those who postoperatively achieved the optimal age-adjusted pelvic incidence (PI) - lumbar lordosis (LL) target were included in this study. Study participants were divided into two groups according to their preoperative sagittal vertical axis (SVA): compensatory balance (SVA <5 cm, group CB) and decompensation (SVA ≥5 cm, group D). Comparisons between the two groups were performed using the χ 2 test or Fisher exact test for categorical variables and the independent t -test or Wilcoxon rank-sum test for continuous variables.

RESULTS

A total of 156 patients whose postoperative sagittal alignment matched the age-adjusted PI-LL target constituted the study cohort. There were 59 patients in group CB and 97 patients in group D. Mean follow-up duration was 50.0 months after surgery. Immediate postoperatively, sacral slope and SVA were significantly greater in group D than in group CB. At the last follow-up, the SVA was significantly greater in group D than in group CB (43.6 vs. 22.7 mm), while no significant differences were found in other sagittal parameters. The Oswestry disability index and Scoliosis Research Society -22 scores at the last follow-up were significantly worse in group D than in group CB.

CONCLUSION

The SVA tended to experience less correction postoperatively, with evidence of further deterioration during follow-up in group D than in group CB. This suboptimal correction of SVA may contribute to the inferior clinical outcomes encountered in group D relative to group CB. Therefore, we recommend correction of PI-LL as close as possible to the lower limit of the suggested PI-LL target range in patients with evidence of preoperative decompensation.

A Muscle-Driven Spine Model for Predictive Simulations in the Design of Spinal Implants and Lumbar Orthoses

Knowledge of realistic loads is crucial in the engineering design process of medical devices and for assessing their interaction with the spinal system. Depending on the type of modeling, current numerical spine models generally either neglect the active musculature or oversimplify the passive structural function of the spine. However, the internal loading conditions of the spine are complex and greatly influenced by muscle forces. It is often unclear whether the assumptions made provide realistic results. To improve the prediction of realistic loading conditions in both conservative and surgical treatments, we modified a previously validated forward dynamic musculoskeletal model of the intact lumbosacral spine with a muscle-driven approach in three scenarios. These exploratory treatment scenarios included an extensible lumbar orthosis and spinal instrumentations. The latter comprised bisegmental internal spinal fixation, as well as monosegmental lumbar fusion using an expandable interbody cage with supplementary posterior fixation. The biomechanical model responses, including internal loads on spinal instrumentation, influences on adjacent segments, and effects on abdominal soft tissue, correlated closely with available in vivo data. The muscle forces contributing to spinal movement and stabilization were also reliably predicted. This new type of modeling enables the biomechanical study of the interactions between active and passive spinal structures and technical systems. It is, therefore, preferable in the design of medical devices and for more realistically assessing treatment outcomes.

Reliability of Vertebral Pelvic Angles in Assessment of Spinal Alignment

STUDY DESIGN

Reliability analysis.

OBJECTIVES

Vertebral pelvic angles (VPA) are gaining popularity given their ability to describe the shape of the spine. Understanding the reliability and minimal detectable change (MDC) is necessary to determine how these measurement tools should be used in the manual assessment of spine radiographs. Our aim is to assess intra- and interobserver intraclass correlation coefficients (ICC) and the MDC in the use of VPA for assessing alignment in adult spinal deformity (ASD).

METHODS

Three independent examiners blindly measured T1, T4, T9, L1, and L4PA twice in ASD patients with a 4-week window after the initial measurements. Patients who had undergone hip or shoulder arthroplasty, fused or transitional vertebrae, or whose hip joints were not visible on radiographs were excluded. Power analysis calculated a minimum sample size of 19. Both intra- and interobserver ICC and MDC, which denotes the smallest detectable change in a true value with 95% confidence, were calculated.

RESULTS

Out of the 193 patients, 39 were ultimately included in the study, and 390 measurements were performed by 3 raters. Intraobserver ICC values ranged from .90 to .99. The interobserver ICC was .97, .97, .96, .95, and .92, and the MDC was 5.3°, 5.1°, 4.8°, 4.9°, and 4.1° for T1, T4, T9, L1, and L4PA, respectively.

CONCLUSION

All VPAs showed excellent intra- and interobserver reliability, however, the MDC is relatively high compared to typical ranges for VPA values. Therefore, surgeons must be aware that substantial alignment changes may not be detected by a single VPA.

Anterior Column Release: With Great Lordosis Comes Great Risk of Complications-A Case Series

STUDY DESIGN

Retrospective review.

OBJECTIVE

We sought to characterize complications associated with anterior column release (ACR).

SUMMARY OF BACKGROUND DATA

Correction of positive sagittal imbalance was traditionally completed with anterior column grafts or posterior osteotomies. ACR is a minimally invasive technique for addressing sagittal plane deformity by restoring lumbar lordosis.

METHODS

We conducted a retrospective review of consecutive patients who underwent ACR in a prospectively kept database at a tertiary care academic center from January 2012 to December 2018. The prespecified complications were hardware failure (rod fracture, hardware loosening, or screw fracture), proximal junctional kyphosis, ipsilateral thigh numbness, ipsilateral femoral nerve weakness, arterial injury requiring blood transfusion, bowel injury, and abdominal pseudohernia.

RESULTS

Thirty-eight patients were identified. Thirty-five patients had ACR at L3-4, 1 had ACR at L4-5, and 1 patient had ACR at L2-3 and L3-4. Eighteen patients (47.4%) had one of the prespecified complications (10 patients had multiple). Ten patients developed hardware failure (26.3%); 8 patients (21.1%) had rod fracture, 4 (10.5%) had screw fracture, and 1 (2.6%) had screw loosening. At discharge, rates of ipsilateral thigh numbness (37.8%) and hip flexor (37.8%)/quadriceps weakness (29.7%) were the highest. At follow-up, 6 patients (16.2%) had ipsilateral anterolateral thigh numbness, 5 (13.5%) suffered from ipsilateral hip flexion weakness, and 3 patients (5.4%) from ipsilateral quadriceps weakness. Arterial injury occurred in 1 patient (2.7%). Abdominal pseudohernia occurred in 1 patient (2.7%). There were no bowel injuries observed.

CONCLUSIONS

ACR is associated with a higher than initially anticipated risk of neurological complications, hardware failure, and proximal junctional kyphosis.

Comparison of clinical and radiological outcomes of SRS-Schwab grade 3-4 and SRS-Schwab 5-6 osteotomies in congenital kyphosis and kyphoscoliosis patients

PURPOSE

This study aimed to evaluate the clinical and radiological outcomes of two patient groups with congenital kyphosis and kyphoscoliosis who underwent posterior surgical correction using Schwab grade 3-4 and Schwab grade 5-6 osteotomies.

METHODS

A retrospective analysis was conducted on 58 patients (35 females and 23 males; mean age: 16.2 yr). Radiological evaluations included preoperative,postoperative,and last follow-up measurements of segmental kyphosis, scoliosis, lumbar lordosis(LL), C7-central sacral vertical line[C7-CSVL] and sagittal vertical axis [SVA], and pelvic parameters (pelvic incidence [PI],pelvic tilt [PT], sacral slope [SS].Clinical evaluations included Scoliosis Research Society-22r (SRS-22r) scores and Oswestry Disability Index (ODI) scores at preoperative and last follow-up time points.

RESULTS

The mean deformity correction was 53.4%. Preoperative segmental kyphosis angles for Schwab grade 3-4 osteotomy (group 1) and Schwab grade 5-6 osteotomy (group 2) were 66.9° and 104.9°, respectively.The last follow-up angles were 33.1° and 48.2° (p < 0.001).No significant loss of correction was observed in either group (p > 0.05). SRS-22r scores improved significantly at the last follow-up (p < 0.001).Similarly, ODI scores improved significantly in both groups (p < 0.001).Neurological complications occurred in 14 (24.1%) patients,including dura injury, spinal nerve root injury, transient incomplete neurological deficits, and spinal cord compression.Mechanical complications were reported in 14 (24.1%) patients and included rod fractures, proximal junction kyphosis, pedicle screw malposition, and pedicle screw loosening.

CONCLUSION

Posterior surgical correction using Schwab grade 3-4 and Schwab grade 5-6 osteotomies yields satisfactory radiological and clinical outcomes in patients with congenital kyphosis and kyphoscoliosis. However, higher osteotomy grades, necessitated by greater deformity severity, are associated with increased complication rates.

Characterization of Lumbar Lordosis: Influence of Age, Sex, Vertebral Body Wedging, and L4-S1

STUDY DESIGN

Retrospective radiographic review.

OBJECTIVE

The objectives of the study were to determine the contributions to lumbar lordosis (LL) through both the vertebrae and the intervertebral disc (IVD), and to investigate the relationships between lumbar sagittal spine measurements and age and gender.

SUMMARY OF BACKGROUND DATA

A small body of literature exists on the relative contributions of vertebral body and IVD morphology to LL, the effects of L4-S1 on overall LL, and the relationships/correlations between lumbar sagittal spine measurements.

METHODS

Patients who met the inclusion criteria were retrospectively evaluated. Measurements included LL, pelvic incidence (PI), and % contributions of vertebral body wedging/IVD wedging/L4-S1 to LL. Patients were separated into groups by age and sex, demographic data were collected, and statistical analysis was completed.

RESULTS

LL decreased with age, although PI remained similar. Females demonstrated increased LL and vertebral body wedging % than males. Males demonstrated increased L4-S1% than females. Despite a decrease in LL with age, patients maintained L4-S1% and IVD wedging %. There was a significant negative relationship between PI and IVD wedging, PI and L4-S1%, and LL and L4-S1%.

CONCLUSIONS

During aging, the lumbar spine loses LL linearly. This occurs in the IVD and vertebral bodies. Females have increased LL compared with males, because of an increase in vertebral body wedging and IVD/vertebral wedging cranial to L4. In patients with high PI or LL, increased LL occurs from cranial to L4 and from vertebral body wedging.

Effect of Baseline Adjacent Segment Degeneration on Clinical Outcomes After Lumbar Fusion

STUDY DESIGN

Cohort Study.

OBJECTIVES

End-stage degenerative segments above fusion levels have been associated with lower rates for surgical adjacent segment disease. We aimed to explore how this degeneration translates into patient reported outcomes.

METHODS

A consecutive series of lumbar fusion patients for degenerative pathologies were enrolled. Preoperative cranial adjacent segment degeneration status was determined using the Combined Imaging Score (CIS). Based on CIS, patients were trichotomized into mild (CIS <7), advanced (CIS 7-10), and end-stage (CIS >10) degeneration tertiles. In analysis, tertiles were adjusted for age, sex, and fusion length to control for potential confounders. The Oswestry Disability Index (ODI) was collected at baseline, 3 months, 1, 2, 5, and 10 years.

RESULTS

197 patients were included. Postoperative improvements were similar across all CIS tertiles at all time-points, except for the marginal 10-point difference at 2-years, in favor of higher degeneration. Despite similar changes, end-stage degeneration (CIS >10) implied marginally lower disability levels at baseline and throughout follow-up.The 10-year all-cause mechanical reoperation rate was lowest in the third tertile (28%, 27%, 22%). Reoperation history was associated with greater disability among advanced degeneration (CIS 7-10); the ODI score difference 9 points, P = .009. Postoperative sagittal alignment was not reflected on physical performance.

CONCLUSIONS

Preoperative adjacent segment degeneration status was only marginally reflected on 10-year disability outcomes. End-stage adjacent segment degeneration signaled lower reoperation risk and favorable functional outcomes. Our findings support the assumption that collapsed, end-stage degenerative segments without stenosis can be safely excluded from fusion constructs.

Automated measurement of pelvic parameters using convolutional neural network in complex spinal deformities: overcoming challenges in coronal deformity cases

BACKGROUND CONTEXT

Accurate and consistent measurement of sagittal alignment is challenging, particularly in patients with severe coronal deformities, including degenerative lumbar scoliosis (DLS).

PURPOSE

This study aimed to develop and validate an artificial intelligence (AI)-based system for automating the measurement of key sagittal parameters, including lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope, with a focus on its applicability across a wide range of deformities, including severe coronal deformities, such as DLS.

DESIGN

Retrospective observational study.

PATIENT SAMPLE

A total of 1,011 standing lumbar lateral radiographs, including DLS.

OUTCOME MEASURE

Interclass and intraclass correlation coefficients (CC), and Bland-Altman plots.

METHODS

The model utilizes a deep-learning framework, incorporating a U-Net for segmentation and a Keypoint Region-based Convolutional Neural Network for keypoint detection. The ground truth masks were annotated by an experienced orthopedic specialist. The performance of the model was evaluated against ground truth measurements and assessments from two expert raters using interclass and intraclass CC, and Bland-Altman plots.

RESULTS

In the test set of 113 patients, 39 (34.5%) had DLS, with a mean Cobb's angle of 14.8°±4.4°. The AI model achieved an intraclass CC of 1.00 across all parameters, indicating perfect consistency. Interclass CCs comparing the AI model to ground truth ranged from 0.96 to 0.99, outperforming experienced orthopedic surgeons. Bland-Altman analysis revealed no significant systemic bias, with most differences falling within clinically acceptable ranges. A 5-fold cross-validation further demonstrated robust performance, with interclass CCs ranging from 0.96 to 0.99 across diverse subsets.

CONCLUSION

This AI-based system offers a reliable and efficient automated measurement of sagittal parameters in spinal deformities, including severe coronal deformities. The superior performance of the model compared with that of expert raters highlights its potential for clinical applications.

High Preoperative T1 Slope is a Marker for Global Sagittal Malalignment

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To develop parameter thresholds obtainable from cervical radiographs that correlate with concomitant thoracolumbar malalignment.

SUMMARY OF BACKGROUND DATA

T1 slope (T1S) is typically discussed in the context of cervical deformity and correlated with health-related quality of life outcomes. Prior research suggests that T1S is related to global alignment; however, a definition for "high" T1S has not been established. Most patients undergoing cervical surgery do not undergo full-spine imaging; therefore, obtaining a parameter associated with thoracolumbar malalignment from cervical radiographs would be beneficial.

METHODS

A database of preoperative adult spinal deformity (ASD) patients was analyzed. Measures obtained from standing lateral radiographs included T1S, thoracic kyphosis (TK), sagittal vertical axis (SVA), T1-pelvic angle (TPA), pelvic tilt (PT), and pelvic incidence minus lumbar lordosis (PI-LL). Decision tree analysis was then used to determine the T1S corresponding to published thresholds for high TK (40 degrees), SVA (40 mm), TPA (25 degrees), and PT (25 degrees). Alignment between high and normal T1S patients was compared.

RESULTS

Two hundred twenty-six preoperative patients were included (mean: 58±16 y 62%F). Larger T1S was correlated with greater SVA (r=0.365), TPA (r=0.302), TK (r=0.606), and PT (r=0.230) (all P<0.001). Decision tree analysis yielded a threshold of 30 degrees for high T1S, which 50% of patients had. Compared with patients with T1S <30 degrees, those with T1S >30 degrees had higher TK (41.5 vs. 25.8 degrees), SVA (78.7 vs. 33.7 mm), TPA (27.6 vs. 18.3 degrees), and PT (26.3 vs. 20.8 degrees), and PI-LL (18.2 vs. 11.7 degrees) (all P<0.05). Seventy-nine percent of patients with high T1S had high TK (T1S <30=13%), 69% had high SVA (T1S <30=38%), 66% had high TPA (T1S <30=37%), 60% had PT >25 degrees (T1S <30=42%), and 47% had PI-LL >20 degrees (T1S <30=34%) (all P<0.05).

CONCLUSION

Higher T1S was associated with worse global alignment. T1S was most strongly associated with TK. A T1S=30 degrees corresponded to high TK, SVA, TPA, and PT thresholds. Therefore, surgeons should consider obtaining full-spine radiographs if a T1S >30 degrees is present on cervical imaging.

Proximal Lumbar Anterior Column Realignment for Iatrogenic Sagittal Plane Adult Spinal Deformity Correction: A Retrospective Case Series

BACKGROUND

Anterior column realignment (ACR) is a powerful minimally invasive surgery technique to restore sagittal alignment in adult spinal deformity (ASD). This can accomplish similar segmental lordosis restoration as 3-column osteotomy with less blood loss and comparable complication rates. ACR can be performed at adjacent disease segments in the proximal lumbar spine in revision cases. However, two thirds of physiologic lordosis occurs between L4-S1, and concerns remain about altered lumbar morphology. We evaluated patients who underwent proximal lumbar ACR for iatrogenic flatback deformity.

METHODS

A total of 19 consecutive patients who underwent L1-2 or L2-3 ACR were retrospectively analyzed. All patients were treated with lateral minimally invasive surgery interbody technique, followed by posterior reconstruction with Smith-Peterson osteotomy. Preoperative and postoperative radiographic and clinical outcomes were obtained.

RESULTS

Mean follow-up was 19 months. All but 1 patient had a history of prior lumbar or lumbo-sacral fusion. Sagittal vertical axis and pelvic incidence-lumbar lordosis decreased from 11.9 cm to 6.1 cm (P < 0.0001) and 34.2° to 12.8° (P < 0.0001). Segmental lordosis increased from -2.7° to 21.9° (P < 0.0001). Proximal lumbar lordosis increased from -0.4° to 22.6° (P < 0.0001), and lordosis distribution index decreased from 79.5% to 48.9% (P < 0.0001). Mean Oswestry Disability Index and numeric pain rating scale back pain scores decreased from 58.0 to 36.2 (P = 0.0041) and 7.9 to 3.4 (P < 0.0001), respectively. Patient-Reported Outcomes Measurement Information System Physical and Mental Health T-scores increased from 34.1 to 43.3 (P = 0.0049) and 40.4 to 45.0 (P = 0.0993), respectively. Major complication rate was 15.8%. One patient required revision for mechanical failure. There were no permanent neurological or vascular injuries.

CONCLUSIONS

Proximal lumbar ACR plus Smith-Peterson osteotomy can achieve sagittal correction with low major complication rates in patients with ASD and prior distal fusion. Differentially increasing proximal lumbar lordosis and lowering lumbar distribution index did not have deleterious effects on radiographic or clinical outcomes. Further work is needed to understand the effect of proximal ACR in the surgical management of ASD.

Is ABO blood type a risk factor for adjacent segment degeneration after lumbar spine fusion?

PURPOSE

This study aimed to explore associations between ABO blood type and postoperative adjacent segment degeneration/disease (ASD) following lumbar spine fusion, as well as evaluate differences in spinopelvic alignment, perioperative care, postoperative complications, and patient-reported outcome measures (PROMs).

METHODS

An ambispective study was performed. Patients who underwent posterolateral or posterior lumbar interbody fusion were included. Demographic, perioperative and postoperative, clinical, and blood type information was recorded. Pre- and post-operative radiographic imaging was analyzed for alignment parameters and development of ASD.

RESULTS

445 patients were included, representing O+ (36.0%), O- (5.2%), A+ (36.2%), A- (6.3%), B+ (12.1%), B- (1.6%), and AB+ (2.7%) blood types. Most patients were female (59.1%), and had a mean age of 60.3 years and BMI of 31.1 kg/m2. Postoperatively, groups did not differ in duration of the hospital (p = 0.732) or intensive care unit (p = 0.830) stay, discharge disposition (p = 0.504), reoperation rate (p = 0.192), or in-hospital complication rate (p = 0.377). Postoperative epidural hematoma was most common amongst A + patients (p = 0.024). Over a mean of 11.0 months of follow-up, all patients exhibited similar improvement in PROMs, with 132 (29.7%) patients developing radiographic evidence of ASD. B + patients were significantly more likely than A + and O + patients to develop spondylolisthesis and ASD (p < 0.05). No significant differences in sagittal alignment parameters and number of levels of fusion were found (p > 0.05).

CONCLUSIONS

This is the first large-scale study to address and demonstrate proof-of-principle that ABO blood type, a non-modifiable risk factor, is associated with ASD following lumbar spine fusion.

The Effect of Changes in Segmental Lordosis on Global Lumbar and Adjacent Segment Lordosis After L5-S1 Anterior Lumbar Interbody Fusion

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVE

Restoration of lordosis in lumbar fusion reduces low back pain, decreases adjacent segment degeneration, and improves postoperative outcomes. However, the potential effects of changes in segmental lordosis on adjacent-level and global lordosis remain less understood. This study aims to examine the relationships between segmental (SL), adjacent-level, and global lumbar lordosis following L5-S1 Anterior Lumbar Interbody Fusion (ALIF).

METHODS

80 consecutive patients who underwent single-level L5-S1 ALIF were divided into 3 groups based on the degree of change (∆) in index-level segmental lordosis: <5° (n = 23), 5°-10° (n = 29), >10° (n = 28). Radiographic parameters measured included global lumbar, segmental, and adjacent level lordosis, sacral slope, pelvic tilt, pelvic incidence, and PI-LL mismatch.

RESULTS

Patients with ∆SL 5°-10° or ∆SL >10° both showed significant increases in global lumbar lordosis from preoperative to final follow-up. However, patients with ∆SL >10° showed statistically significant losses in adjacent level lordosis at both immediate postoperative and final follow-up compared to preoperative. When comparing patients with ∆SL >10° to those with ∆SL 5-10°, there were no significant differences in global lumbar lordosis at final follow-up, due to significantly greater losses of adjacent level lordosis in these patients.

CONCLUSION

The degree of compensatory loss of lordosis at the adjacent level L4-L5 correlated with the extent of segmental lordosis creation at the index L5-S1 level. This may suggest that the L4 to S1 segment acts as a "harmonious unit," able to accommodate only a certain amount of lordosis and further increases in segmental lordosis may be mitigated by loss of adjacent-level lordosis.

Postsurgical outcomes differ according to baseline sagittal alignment status even in patients achieving adequate correction relative to age-adjusted alignment target for adult spinal deformity

BACKGROUND CONTEXT

Baseline severities of sagittal malalignment and degrees of pelvic compensation may affect postsurgical outcomes differently after adult spinal deformity (ASD) surgery, even if the patients achieved optimal correction of sagittal malalignment.

PURPOSE

To investigate whether postsurgical outcomes vary according to baseline sagittal alignment and pelvic compensation status in patients achieving adequate correction relative to age-adjusted alignment target in ASD surgery.

STUDY DESIGN/SETTING

Retrospective study PATIENT SAMPLE: Patients who underwent ≥ 5-level fusion to the pelvis for ASD; achieved matched correction relative to age-adjusted pelvic incidence (PI)-lumbar lordosis (LL); and completed ≥ 2-year follow-up.

OUTCOME MEASURES

Radiographic results, mechanical failures, and clinical outcomes METHODS: Patients were divided into three groups based on baseline sagittal vertical axis (SVA) and pelvic tilt (PT)/PI ratio (median value of PT/PI ratio = 0.61): Group A (SVA < 5 cm), Group B (SVA ≥ 5 cm and PT/PI ratio <0.61, and Group C (SVA ≥ 5 cm and PT/PI ratio ≥ 0.61). Radiographic results, mechanical failures, and clinical outcomes were compared among the three groups.

RESULTS

A total of 153 patients were included in the study. They were predominantly female (89.5%), with a mean age of 68.3 years. The mean follow-up duration was 49.0 months. There were 50 patients in group A (SVA < 5cm), 53 in group B (SVA ≥ 5cm and low PT/PI), and 50 in group C (SVA ≥ 5cm and high PT/PI). No significant differences were observed in all radiographic parameters at six weeks. At the last follow-up, the PI-LL was comparable among the three groups; however, the SVA was significantly greater in groups B and C than in group A (46.5mm and 46.9mm vs. 31.5mm, p=.039). The PT at the last follow-up was significantly lower in group B than in group A and C (22.4° vs. 26.0° and 28.2°, respectively, p=.001). The rates of mechanical failure and subsequent revision surgery and did not differ among the groups. The final clinical outcomes were comparable among the three groups.

CONCLUSIONS

This study revealed that patients in groups B and C were likely to have a suboptimal sagittal alignment status at the last follow-up compared with those in group A. Tailored approaches considering patient's baseline alignment and compensatory status are recommended to optimize the final sagittal alignment status.

The Role of Pelvic Compensation in Sagittal Balance and Imbalance: The Impact of Pelvic Compensation on Spinal Alignment and Clinical Outcomes Following Adult Spinal Deformity Surgery

BACKGROUND AND OBJECTIVES

The Scoliosis Research Society (SRS)-Schwab system does not include a pelvic compensation (PC) subtype, potentially contributing to gaps in clinical characteristics and treatment strategy for deformity correction. It also remains uncertain as to whether PC has differing roles in sagittal balance (SB) or imbalance (SI) status. To compare radiological parameters and SRS-22r domains between patients with failed pelvic compensation (FPC) and successful pelvic compensation (SPC) based on preoperative SB and SI.

METHODS

A total of 145 adult spinal deformity patients who received deformity correction were analyzed. Radiographic and clinical outcomes were collected for statistical analysis. Patients were classified into 4 groups based on the median value of PT/PI ratio (PTr) and the cutoff value of SB. Patients with low PTr and high PTr were defined as FPC and SPC, respectively. Radiographic and clinical characteristics of different groups were compared.

RESULTS

Patients with SPC exhibited significantly greater improvements in lumbar lordosis, pelvic tilt, PTr, and T1 pelvic angle as compared to patients with FPC, irrespective of SB or SI. No apparent differences in any of SRS-22r domains were observed at follow-up when comparing the SB-FPC and SB-SPC patients. However, patients with SI-SPC exhibited significantly better function, self-image, satisfaction, and subtotal domains at follow-up relative to those with SI-FPC. When SI-FPC and SI-SPC patients were subdivided further based on the degree of PI-LL by adjusting for age, the postoperative function and self-image domains were significantly better in the group with overcorrection of PI-LL than undercorrection of PI-LL in SI-FPC patients. However, no differences in these SRS-22r scores were observed when comparing the subgroups in SI-SPC patients.

CONCLUSION

Flexible pelvic rotation is associated with benefits to the correction of sagittal parameters, irrespective of preoperative SB or SI status. However, PC is only significantly associated with clinical outcomes under SI. Patients with SI-FPC exhibit poorer postoperative clinical outcomes, which should be recommended to minimize PI-LL.

Alignment considerations in degenerative spinal conditions: A narrative review

Background

With an aging population, degenerative spinal diseases are contributing significantly to the healthcare's burden. Spinal alignment in the context of adult spinal deformities has become an important domain of research.

Methods

We conducted a narrative review of the latest considerations in spinal alignment within the context of degenerative spinal conditions, discussed current strategies for morphological assessment and finally identified potential areas for future research.

Results

This review reported that degenerative spinal conditions lead to a complex disruption of spinal alignment. It also highlighted the importance of spino-pelvic alignment with specific attention to compensatory mechanisms that occur in response to spinal deformities. Emerging technologies including Artificial Intelligence and epigenetics are showing promises in terms of patient care.

Conclusions

Understanding spinal alignment in degenerative conditions underscores the importance of dynamic and individualized assessments. Future research should integrate emerging technologies along with traditional clinical practices in order to optimize patient outcomes and minimize complications for patients suffering from degenerative spinal diseases.

Characteristic of Paraspinal Muscle Change in Coronal Sub-type of Degenerative Lumbar Scoliosis and its Potential Clinical Significance

OBJECTIVE

Clarifying paraspinal muscle (PM) change in degenerative lumbar scoliosis (DLS) is positive to evaluate the progression of scoliosis. This research compares the characteristic of PM change among different coronal sub-types of DLS and explores its potential clinical significance.

METHODS

A total of 84 DLS patients between June 2019 to December 2021 were retrospectively analyzed. Patients were classified into three types based on the coronal balance distance (CBD): Type A, CBD <3 cm; Type B: C7 Plumb Line (C7PL) shifted to the concave side of the curve, and CBD >3 cm; Type C: C7PL shifted to the convex side of the curve, and CBD >3 cm. Fat infiltration rates in the multifidus (MS) and erector spinae (ES) at the apex of the main and fractional curves, and spinopelvic parameters were analyzed statistically. Pearson's or Spearman's correlation was applied to analyze the correlation between asymmetric degree of PM change and these parameters in three types.

RESULTS

There were 62 cases with coronal sub-Type A, 6 cases with Type B, and 16 cases with Type C. Patients in Type B and C demonstrated higher fat infiltration in MS on the concave side of both the main and fractional curves when compared to those in Type A. The asymmetric degree of ES change was positively correlated with CBD at the apex of the main curve in Type B and at the apex of the fractional curve in Type C respectively, and that of MS was positively correlated with apical vertebral rotation, while negatively strong-correlated with pelvic incidence and sacral slope in Type C.

CONCLUSION

PM fatty infiltration presented difference among varied coronal sub-types of DLS patients. The CBD in Type B and C patients was correlated with the asymmetric degree of ES change.

Global tilt angle in spinal alignment of asymptomatic older women with low bone mass

This study investigated the relationship between sagittal spinal alignment and musculoskeletal health in older women, particularly those exhibiting diminished bone density without apparent symptoms. The study assessed the impact of global tilt (GT) and the presence of coronal malalignment on spinal health. The research involved 165 asymptomatic older women with an average age of 68.91 ± 7.25 years and average body mass index of 24.26 ± 3.66 kg/m². Comprehensive standing anteroposterior and lateral spine radiographs were used for assessment. Through multivariate linear regression analysis, the study identified significant correlations between increased GT angles and various factors, including coronal malalignment, the C7 slope, and pelvic incidence. This led to the formulation of a predictive GT model: GT = -9.79 + 0.06 × menopausal period + 0.19 × body mass index (BMI)- 0.81 × average T score - 0.11 × grip strength + 3.03 × (presence of coronal malalignment) + 0.08 × sagittal vertical axis (SVA) + 0.12 × C7 slope - 0.35 × upper lumbar lordosis (ULL) - 0.43 × lower lumbar lordosis (LLL) + 0.70 × pelvic incidence (PI), with an adjusted R² of 0.816. The study findings highlight the prevalence of coronal malalignment in this demographic and its significant associations with critical spinal parameters. The proposed GT predictive model may enable development of personalized treatment plans for older women with low bone mass.

Characterization of Patients with Poor Clinical Outcome after Adult Spinal Deformity Surgery: A Multivariate Analysis of Mean 8-Year Follow-Up Data

Background/Objective: Limited data exist regarding the long-term clinical outcomes and related factors after adult spinal deformity (ASD) surgery. This study aims to characterize patients who experienced poor clinical outcomes during long-term follow-up after ASD surgery. Methods: Patients who underwent ASD surgery with ≥5-vertebra fusion including the sacrum and ≥5-year follow-up were included. They were divided into two groups according to the Oswestry Disability Index (ODI) at the last follow-up: group P (poor outcome, ODI > 40) and group NP (non-poor outcome, ODI ≤ 40). Clinical variables, including patient factors, surgical factors, radiographic parameters, and mechanical complications (proximal junctional kyphosis [PJK] and rod fracture), were compared between the groups. Results: A total of 105 patients were evaluated, with a mean follow-up of 100.6 months. The mean age was 66.3 years, and 94 patients (89.5%) were women. There were 52 patients in group P and 53 patients in group NP. Univariate analysis showed that low T-score, postoperative correction relative to age-adjusted pelvic incidence-lumbar lordosis, T1 pelvic angle (TPA) at last follow-up, and PJK development were significant factors for poor clinical outcomes. Multivariate analysis identified PJK as the single independent risk factor (odds ratio [OR] = 3.957 for PJK development relative to no PJK, OR = 21.141 for revision surgery for PJK relative to no PJK). Conclusions: PJK development was the single independent factor affecting poor clinical outcomes in long-term follow-up. Therefore, PJK prevention appears crucial for achieving long-term success after ASD surgery.

Impact of postoperative spinal malalignment on postoperative health-related quality of life after long-level fixation for degenerative lumbar scoliosis: does residual coronal angularity matter?

PURPOSE

This study evaluates the influence of spinal malalignment on health-related quality of life (HRQOL) in a long-level fusion spine.

METHODS

This was a retrospective analysis of 121 consecutive patients with DLS after long-segment fusion. HRQOL and radiographic parameters were collected at final follow-up. For postoperative residual Cobb angle (CA), patients were divided as follows: group (0) (CA < 10°), group (+) (CA 10°∼20 °), and group (++) (CA > 20°). For postoperative coronal vertical axis (CVA), patients were separated as follows: group (0) (CVA < 2 cm), group (+) (CVA 2 ∼ 3 cm), and group (++) (CVA > 3 cm). Patients were also grouped by the sagittal modifiers as group (0), group (+), and group (++) according to the Scoliosis Research Society (SRS)-Schwab classification, respectively.

RESULTS

Visual analog scale (VAS) for back was significantly lower in CA 10°∼20° group compared to other groups. Patients with remnant CA > 20° showed worse Oswestry Disability Index (ODI), SRS-22 and the 36-item Short Form Health Survey (SF-36) - physical component scores (PCS). Sagittal vertical axis (SVA) showed significant correlation with HRQOLs after surgery, and the statistical significance of ODI, SRS-22 and SF-36 scores was observed among subgroups.

CONCLUSIONS

In long-level fused spine, residual CA > 20° resulted in worse clinical outcomes and was recommended to avoid during surgery. And 10° to 20° residual CA was acceptable in DLS patients and even better than Cobb angle < 10° in several HRQOLs, therefore strictly pursing upright alignment seems unnecessary. SVA also showed effectiveness in assessing HRQOL in the fixed spine.

Preoperative Planning of Lumbar Lordosis for Adult Degenerative Scoliosis Surgery in the Chinese Population

OBJECTIVE

Pelvic incidence minus lumbar lordosis mismatch (PI-LL) is directly related to poor quality of life in adult degenerative scoliosis (ADS) patients. The purpose of the study was to determine the most appropriate postoperative PI-LL value for patients with ADS.

METHODS

The medical records of patients with ADS in our department were retrospectively collected. The data included age, sex, body mass index, age-adjusted Charlson comorbidity index, osteopenia, length of hospital stay, operative duration, estimated blood loss, American Society of Anesthesiologists score, number of fusion levels, lumbar lordosis, sagittal vertical axis, pelvic incidence, PI-LL, Scoliosis Research Society-22 score, Oswestry Disability Index score, and mechanical complications.

RESULTS

A total of 316 patients were enrolled. PI-LL, lumbar lordosis, sagittal vertical axis, Scoliosis Research Society-22 score, Oswestry Disability Index score at the time of last follow-up were 20.7 ± 8.5°, 23.4 ± 14.1°, 4.0 ± 2.1 cm, 3.7 ± 0.9, and 18.1 ± 5.5, respectively. In terms of mechanical complications, 88 patients (27.8%), 34 patients (10.8%), and 19 patients (6.0%) had proximal junctional kyphosis, distal junctional kyphosis, and implant-related complications, respectively. In the fully adjusted model, compared with 0 grade PI-LL group and ++ grade PI-LL group, + grade PI-LL group had the best clinical outcomes and the fewest mechanical complications. The stability of these conclusions was verified in sensitivity analyses.

CONCLUSIONS

Optimal PI-LL value should be 10°-20° after corrective surgery in patients with ADS, which is associated with excellent clinical outcomes and lower complication rates. Previous criteria may be at risk of overcorrection, which may lead to proximal junctional kyphosis.

Long-term Outcomes After Adult Spinal Deformity Surgery Using Lateral Interbody Fusion: Short Versus Long Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To investigate long-term outcomes after short or long fusion for adult spinal deformity using lateral interbody fusion.

SUMMARY OF BACKGROUND DATA

Lateral interbody fusion is commonly used in adult spinal deformity surgery. Favorable short-term outcomes have been reported, but not long-term outcomes. Lateral interbody fusion with strong ability to correct deformity may allow the selection of short fusion techniques.

MATERIALS AND METHODS

We retrospectively reviewed adults who underwent this surgery with a minimum of 5 years of follow-up. Short fusion with the uppermost instrumented vertebra in the lumbar spine was performed in patients without degenerative changes at the thoracolumbar junction (S-group); others underwent long fusion with the uppermost instrumented vertebra in the thoracic spine (L-group). We assessed radiographic and clinical outcomes.

RESULTS

Short fusion was performed in 29 of 54 patients. One patient per group required revision surgery. Of the remainder, with similar preoperative characteristics and deformity correction between groups, correction loss (pelvic incidence-lumbar lordosis, P =0.003; pelvic tilt, P =0.005; sagittal vertical axis, P ˂0.001) occurred within 2 years postoperatively in the S-group, and sagittal vertical axis continued to increase until the 5-year follow-up ( P =0.021). Although there was a significant change in Oswestry disability index in the S-group ( P =0.031) and self-image of Scoliosis Research Society 22r score in both groups ( P =0.045 and 0.02) from 2- to 5-year follow-up, minimum clinically important differences were not reached. At 5-year follow-up, there was a significant difference in Oswestry Disability Index ( P =0.013) and Scoliosis Research Society 22r scores (function: P =0.028; pain: P =0.003; subtotal: P =0.006) between the groups, but satisfaction scores were comparable and Oswestry Disability Index score (29.8%) in the S-group indicated moderate disability.

CONCLUSIONS

Health-related quality of life was maintained between 2- and 5-year follow-up in both groups. Short fusion may be an option for patients without degenerative changes at the thoracolumbar junction.

LEVEL OF EVIDENCE

III.

Sarcopenia Predicts the Development of Early Adjacent Segment Disease After Transforaminal Lumbar Interbody Fusion

BACKGROUND AND OBJECTIVES

Predicting the development of adjacent segment disease (ASD) after lumbar spine fusion would help guide preoperative and postoperative therapies to prevent reoperation. We sought to evaluate whether sarcopenia predicts the development of early ASD after transforaminal lumbar interbody fusion (TLIF).

METHODS

Retrospective data were collected from 109 patients who underwent TLIF from 2013 to 2023. Patients older than 18 years who underwent elective posterior midline approach TLIF were included. Patients with prior lumbar instrumented fusions, cases of trauma, central nervous system infection, cancer, or long-construct thoracolumbar deformity corrections and those who lacked sufficient follow-up were excluded. The primary outcome was radiographic ASD development within 3 years of surgery. Psoas volumetric measurements were recorded from the most recent preoperative MRI. Odds ratios were calculated with logistic regression analyses.

RESULTS

In 109 patients undergoing elective TLIF, 22 (20.2%) developed ASD within 3 years. Gender, body mass index, and extent of surgery were not associated with ASD development. Multivariate analysis showed left/right psoas cross-sectional area, and psoas:vertebral body ratio (P:VBR) predicted early ASD (P < .0001). Sarcopenia was further categorized as having bilateral P:VBR ≥1 SD below gender mean (T-score -1). Of 18 sarcopenic patients, 15 developed early ASD (83.33%) vs 7 of 91 nonsarcopenic patients (7.69%; P < .0001). Postoperative mismatch between pelvic incidence and lumbar lordosis was predictive of ASD on univariate (P = .0480) but not multivariate analysis. Pelvic tilt and lumbar lordosis postoperatively were not associated with early ASD.

CONCLUSION

Sarcopenia, measured by decreased psoas area and P:VBR, predicts ASD formation within 3 years of surgery. Morphometric analysis of psoas size is a simple tool to identify patients at risk of developing ASD. This information can potentially guide preoperative and postoperative therapies, affect surgical decision making, and effectively counsel patients on risks of reoperation.

Anterior Column Realignment Using an Anterior-To-Psoas Approach: A Radiographic-Anatomic Feasibility Study at L1-L5

STUDY DESIGN

Cross-sectional radioanatomic study.

OBJECTIVE

To determine the feasibility of performing an anterior column realignment (ACR) using an anterior-to-psoas (ATP) approach at L1-L5.

METHODS

Axial magnetic resonance images (MRI) of the L1-L5 disc levels obtained at a single institution were obtained and analyzed. The feasibility of performing an ACR was assessed using a combination of the size of the left oblique corridor (OC), the psoas morphology using the modified Moro classification, and the anterior disc edge to great vessel distance.

RESULTS

Three hundred MRI studies obtained from 300 patients were included. All patients had a measurable left OC at the L1-L4 levels. Twenty patients (6.7%) had no measurable OC at the L4-L5 level. According to the modified Moro's classification, a high-rising psoas was seen in 4 patients (1.3%) at the L3-L4 level and 57 patients (19.0%) at the L4-L5 level. An ALL release was considered high risk due to no measurable space between the anterior disc edge and the great vessels in 54 patients (18.0%) at the L1-L2 level, 39 patients (13.0%) at the L2-L3 level, 119 patients (39.7%) at the L3-L4 level, and 226 patients (75.3%) at the L4-L5 level.

CONCLUSION

ACR using an ATP approach is the most radioanatomically feasible at L2-L3. The L4-L5 level has the highest risk with regards to both the ATP approach and the ALL release for an ACR due to high rates of unmeasurable left OC and space between the anterior disc edge and the great vessels.

Worse Patient-Reported Outcomes and Spino-Pelvic Parameters After Total Hip Arthroplasty for Rapidly Progressive Osteoarthritis of the Hip Compared to Osteoarthritis: A Propensity-Matched Cohort Study

BACKGROUND

This study aimed to assess the association between the disease process of hip osteoarthritis and total hip arthroplasty (THA) outcomes; this is a critical issue, as rapid progression has been postulated to be responsible for patient dissatisfaction after THA.

METHODS

This retrospective case-control study included 255 patients who underwent THA and completed a mean follow-up duration of 42.1 months (range, 24.0 to 77.0). We classified patients into those who had (n = 26) and did not have (n = 229) rapidly progressive osteoarthritis of the hip (RPOA), defined as a narrowing rate of joint space ≥ 2 mm yearly or a ≥ 50% loss within 12 months, excluding any other cause of a destructive arthropathy. Propensity score-matched cohorts for age, sex, body mass index, and spino-pelvic measures were created, and the outcomes were compared between the 2 groups.

RESULTS

After successfully matching RPOA (n = 25) and non-RPOA patients (n = 50), there were significant differences in minimum clinically important difference (P = .009 for European Quality of Life 5-Dimension, and P < .001 for low back pain), patient acceptable symptom state (P = .015 for European Quality of Life 5-Dimension, and P < .001 for Hip Disability and Osteoarthritis Outcome Score Joint Replacement score), patient satisfaction (P = .028), and T1 pelvic angle as an indicator of global sagittal spinal deformity (P = .017). There was a correlation between T1 pelvic angle and low back pain in the RPOA group (R = 0.628, P < .001).

CONCLUSIONS

Patients who exhibited RPOA before undergoing THA showed worse patient-reported outcomes compared with those who did not have rapid progression. Our study highlights the critical role of the disease process in influencing THA outcomes, advocating for a paradigm shift toward more meticulous preoperative evaluations, including global spinal deformity, standardized diagnostic criteria, and tailored interventions.

Lumbar pedicle subtraction osteotomy: techniques and outcomes

Pedicle subtraction osteotomy has been thoroughly described and studied over the past 2 decades, being applied mainly in the lumbar spine, followed by the thoracic spine. Our better understanding of alignment biomechanics, and the progressive refinements of the surgical technique over time made it a very efficient procedure for the management of fixed sagittal malalignment. However, a long learning curve is mandatory to mitigate the associated risks particularly neurological deficits and achieve satisfactory clinical and radiological outcomes with an acceptable rate of complications.

Sagittal spinal alignment measurements and evaluation: Historical perspective

Spinal alignment analysis play an important role in evaluating patients and planning surgical corrections for adult spinal deformity. The history of these parameters is relatively short with the first parameter, the Cobb angle, introduced in 1948 as part of an effort to improve scoliosis evaluation. New developments in the field were limited for nearly 30 years before better imaging technology encouraged new theories and later data about spinal alignment and the relationship between the spine and pelvis. These efforts would ultimately contribute to the creation of foundational spinal alignment parameters, including pelvic incidence, pelvic tilt, and sacral slope. By the 1990s, spinal alignment had become a sustained area of investigation for spinal surgeons and researchers. Novel alignment parameters have since been introduced as our knowledge has evolved and has allowed for valuable research that demonstrates the clinical and surgical value of alignment measurement. This manuscript will explore the history of spinal alignment analysis over the decades.

Lumbar Lordosis Redistribution and Segmental Correction in Adult Spinal Deformity: Does it Matter?

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVE

Evaluate the impact of correcting normative segmental lordosis values on postoperative outcomes.

BACKGROUND

Restoring lumbar lordosis magnitude is crucial in adult spinal deformity surgery, but the optimal location and segmental distribution remain unclear.

PATIENTS AND METHODS

Patients were grouped based on offset to normative segmental lordosis values, extracted from recent publications. Matched patients were within 10% of the cohort's mean offset, less than or over 10% were undercorrected and overcorrected. Surgical technique, patient-reported outcome measures, and surgical complications were compared across groups at baseline and two years.

RESULTS

In total, 510 patients with a mean age of 64.6, a mean Charlson comorbidity index 2.08, and a mean follow-up of 25 months. L4-5 was least likely to be matched (19.1%), while L4-S1 was the most likely (24.3%). More patients were overcorrected at proximal levels (T10-L2; undercorrected, U: 32.2% vs. matched, M: 21.7% vs. overcorrected, O: 46.1%) and undercorrected at distal levels (L4-S1: U: 39.0% vs. M: 24.3% vs. O: 36.8%). Postoperative Oswestry disability index was comparable across correction groups at all spinal levels except at L4-S1 and T10-L2/L4-S1, where overcorrected patients and matched were better than undercorrected (U: 32.1 vs. M: 25.4 vs. O: 26.5, P =0.005; U: 36.2 vs. M: 24.2 vs. O: 26.8, P =0.001; respectively). Patients overcorrected at T10-L2 experienced higher rates of proximal junctional failure (U: 16.0% vs. M: 15.6% vs. O: 32.8%, P <0.001) and had greater posterior inclination of the upper instrumented vertebrae (U: -9.2±9.4° vs. M: -9.6±9.1° vs. O: -12.2±10.0°, P <0.001), whereas undercorrection at these levels led to higher rates of revision for implant failure (U: 14.2% vs. M: 7.3% vs. O: 6.4%, P =0.025).

CONCLUSIONS

Patients undergoing fusion for adult spinal deformity suffer higher rates of proximal junctional failure with overcorrection and increased rates of implant failure with undercorrection based on normative segmental lordosis.

LEVEL OF EVIDENCE

Level IV.

How Do Spinopelvic Characteristics Change Post-Total Hip Arthroplasty? A Longitudinal Assessment Raising Awareness of the Postoperative Period

BACKGROUND

Spinopelvic characteristics, including sacral slope (SS), are commonly evaluated in different positions pre-total hip arthroplasty (THA). This study aimed to: 1) investigate the change in spinopelvic parameters at 7 days (early) and 1-year post-THA; and 2) identify patient characteristics associated with a change in SS of more than 7° post-THA.

METHODS

We prospectively studied 250 patients who underwent unilateral THA [132 women, age 66 years (range, 32 to 88)] and underwent biplanar images preoperatively and at 7 days and 1-year post-THA. Parameters measured included pelvic incidence, standing lumbar lordosis, SS, and proximal femoral angle (PFA). A SS change ≥ 7° was considered the threshold as it would result in more than a 5° change in cup orientation.

RESULTS

Early post-THA SSstanding remained within ± 6º from preoperative measurements in 75% of patients, reduced by ≥ 7° in 9%, and increased by ≥ 7° in 16%. Those that showed a reduction in SS had the lowest PFA and the highest SS pre-THA (P = .028, .107, and < 0.001, respectively). From 7 days until the 1-year mark, pelvic tilt increased, SS reduced (mean: -4º, range: -29 to 17º, P < .001), and patients stood with greater hip extension ΔPFAstanding (mean 7°, range: -34 to 37°, P < .001). At 1 year, SSseated had remained within ± 6º, relative to the pre-THA value, in 49% of patients.

CONCLUSIONS

Standing spinopelvic characteristics, especially SSstanding, remain within ±6° in three-quarters of patients both early- and at 1-year post-THA. In the remaining cases, pelvic tilt changes significantly. In 9% of cases, SS reduces ≥ 7° early THA, probably due to the alleviation of fixed-flexion contractures. The SSseated changes by ≥ ± 7° in almost 50% of cases in this study, and its clinical value as a preoperative planning tool should be questioned.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Spinopelvic Parameters in the Elderly: Does Inadequate Correction Portend Worse Outcomes?

Introduction

This study aimed to compare the outcomes of corrective fusion for adult spinal deformity (ASD) in older people using two different sagittal correction goals: the conventional formula of "pelvic incidence (PI)-lumbar lordosis (LL) mismatch <10°" and an undercorrection strategy based on the range of 10°≤PI-LL≤20°.

Methods

A total of 102 consecutive patients (11 male and 91 female patients; mean age, 72.0 years) aged above 65 years with scoliosis >20° or LL<20° who had undergone long-segment fusion from the lower thoracic spine to the pelvis for ASD and had been followed-up for a minimum of two years at our institution since March 2013 were included in this retrospective study. After excluding patients with PI-LL≤-10° on postoperative standing radiographs, the remaining patients were divided into two groups: 31 patients with 10°≤PI-LL≤20° (U group) and 63 patients with -10°

Results

The incidence of proximal junctional kyphosis and mechanical failure was not significantly different between the groups (p=0.659 and 1.000, respectively). After excluding patients who underwent reoperation due to mechanical failure, there were no differences in the Oswestry Disability Index (ODI) and each domain of the Visual Analog Scale score, Scoliosis Research Society-22r patient questionnaire (SRS-22r), or the short form 36 health survey questionnaire at the final observation between the U (n=27) and M (n=57) groups. In addition, the non-inferiority and equivalence of the U group to the M group were demonstrated in all domains of the SRS-22r and ODI. Furthermore, the superiority of the U group was demonstrated by the functional domain of SRS-22r.

Conclusions

For the sagittal correction goal in corrective fusion surgery for ASD in the elderly, strict adherence to "PI-LL mismatch <10°" is not necessary and "PI-LL≤20°" may be acceptable.

Collapse

Key Words

• Scoliosis Research Society-Schwab classification
• adult spinal deformity
• elderly patients with spinal deformity
• extensive corrective fusion
• pelvic incidence minus lumbar lordosis mismatch
• sagittal corrective goal
• undercorrection

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Masanari Takami Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Shunji Tsutsui Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Keiji Nagata Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Iwasaki Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Akihito Minamide Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Spine Center, Dokkyo Medical University Nikko Medical Center, Nikko, Japan
Yasutsugu Yukawa Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Spine Center, Nagoya Kyoritsu Hospital, Nagoya, Japan
Motohiro Okada Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan Department of Orthopaedic Surgery, Sumiya Orthopaedic Hospital, Wakayama, Japan
Ryo Taiji Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Shizumasa Murata Department of Orthopaedic Surgery, Shingu Municipal Medical Center, Shingu, Japan
Takuhei Kozaki Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Hashizume Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
Hiroshi Yamada Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan

Collapse

Stiffness-related disability following long segmental posterior instrumentation and fusion: is it influenced by postoperative spinopelvic alignment?

PURPOSE

The aims of this study were to investigate the correlations between Chinese version of Lumbar Stiffness Disability Index (C-LSDI) and other clinical outcomes, and to identify the factors independently affecting stiffness-related disability after long-segment fusion in patients with degenerative lumbar scoliosis (DLS).

METHODS

We performed a retrospective study of 118 consecutive surgically treated DLS cases at a single institute. Pre- and post-operative radiological parameters and postoperative health related quality of life (HRQOL) were examined to determine their correlation coefficients with postoperative C-LSDI. Patients were divided into two groups by the medium number of postoperative C-LSDI: low-stiffness group (C-LSDI < 48 points) and high-stiffness group (C-LSDI ≥ 48 points). Subsequently, differences between the two groups were assessed, and the presumed factors affecting C-LSDI evaluation were further analyzed.

RESULTS

Coronal parameters and global sagittal parameters showed significant correlations with postoperative C-LSDI. The correlation coefficients between C-LSDI and Oswestry Disability Index (ODI), Japanese Orthopedic Association-29 (JOA-29), the Scoliosis Research Society-22 questionnaire (SRS-22) Function, and the Short Form-36 Health Survey (SF-36) Physical Component Scores were over 0.5. In multiple linear regression, postoperative sagittal vertical axis (β = 0.084, p = 0.025), fusion levels (β = 2.13, p = 0.012), and body mass index (β = 0.867, p = 0.022) were independent related factors for C-LSDI.

CONCLUSION

This study showed that all HRQOLs demonstrated the varying degree of correlations with C-LSDI, of which the ODI, JOA-29, SRS-22 Function, and SF-36 PCS were most relevant, with moderate strength of associations.Moreover, longer fusion levels, higher BMI, and greater postoperative SVA independently affect C-LSDI after long segmental posterior instrumentation and fusion for DLS.

Modern Concepts in Sagittal Curve Measurement: Comparison of Spline-Based and Fixed Landmark Measurements in a Cohort of 1520 Healthy Subjects

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

Our objective was to compare the spline-based measurement of sagittal spinal curvatures to fixed landmarks in a normative population.

SUMMARY OF BACKGROUND DATA

Recent research has stressed the importance of considering sagittal curvature in its entirety using a spline reconstruction. To date, no data supports the superiority of this method in comparison to classic measurement methods.

PATIENTS AND METHODS

Full-spine biplanar radiographs of subjects over 20 years old who had normal radiographs were analyzed. Thoracic kyphosis (TK) and lumbar lordosis (LL) were measured following two modalities: either using predefined landmarks (TK T1T12 , TK T5T12 , and LL L1S1 ) or spline-based measurement (TK Spline and LL spline ).

RESULTS

A total of 1520 subjects were included (mean 54yo). The mean difference between TK spline and TK T1T12 was 1.4° and between TK spline and TK T5T12 was 11.7° ( P <0.001). LL spline was significantly larger than LL L1S1 (55° vs . 54°, P<0.001 ). LL spline and LL L1S1 were correlated ( R =0.950, P <0.001). Pelvic incidence had no influence on the difference between LL spline and LL L1S1 ( R =-0.034, P= 0.184). Using LL L1S1 measurements, LL was underestimated in 17% of the cases. The comparison of outlier distributions according to age groups ( P =0.175), sex ( P =0.937), or pelvic incidence groups ( P =0.662) found no difference. There were significantly more outliers in Roussouly type 1 compared with other types (56%, P <0.001).

CONCLUSION

Our results suggest that the use of TK T1T12 and LL L1S1 is acceptable to assess spinal sagittal curvatures. However, TK T5T12 is not accurate for the thoracic curve and should be used with caution. LL L1S1 can be used to accurately assess the lumbar curve, except in Roussouly type 1.

Preoperative low Hounsfield units in the lumbar spine are associated with postoperative mechanical complications in adult spinal deformity

PURPOSE

To determine the most valid bone health parameter to predict mechanical complications (MCs) following surgery for adult spinal deformity (ASD).

METHODS

This multicenter study retrospectively examined the records of patients who had undergone fusion of three or more motion segments, including the pelvis, with a minimum two-year follow-up period. Patients with moderate and severe global alignment and proportion scores were included in the study and divided into two groups: those who developed MCs and those who did not. Bone mineral density (BMD) of the lumbar spine and femoral neck was measured using dual-energy X-ray absorptiometry, and Hounsfield units (HUs) were measured in the lumbar spine on computed tomography. Radiographic parameters were evaluated preoperatively, immediately after surgery, and at final follow-up.

RESULTS

Of 108 patients, 30 (27.8%) developed MCs, including 26 cases of proximal junctional kyphosis/failure, 2 of distal junctional failure, 6 of rod fracture, and 11 reoperations. HUs were significantly lower in patients who experienced MCs (113.7 ± 41.1) than in those who did not (137.0 ± 46.8; P = 0.02). BMD did not differ significantly between the two groups. The preoperative and two-year postoperative global tilt, as well as the immediately postoperative sagittal vertical axis, were significantly greater in patients who developed MCs than in those who did not (P = 0.02, P < 0.01, and P = 0.01, respectively).

CONCLUSION

Patients who experienced MCs following surgery for ASD had lower HUs than those who did not. HUs may therefore be more useful than BMD for predicting MCs following surgery for ASD.

Artificial intelligence automatic measurement technology of lumbosacral radiographic parameters

Background

Currently, manual measurement of lumbosacral radiological parameters is time-consuming and laborious, and inevitably produces considerable variability. This study aimed to develop and evaluate a deep learning-based model for automatically measuring lumbosacral radiographic parameters on lateral lumbar radiographs.

Methods

We retrospectively collected 1,240 lateral lumbar radiographs to train the model. The included images were randomly divided into training, validation, and test sets in a ratio of approximately 8:1:1 for model training, fine-tuning, and performance evaluation, respectively. The parameters measured in this study were lumbar lordosis (LL), sacral horizontal angle (SHA), intervertebral space angle (ISA) at L4-L5 and L5-S1 segments, and the percentage of lumbar spondylolisthesis (PLS) at L4-L5 and L5-S1 segments. The model identified key points using image segmentation results and calculated measurements. The average results of key points annotated by the three spine surgeons were used as the reference standard. The model's performance was evaluated using the percentage of correct key points (PCK), intra-class correlation coefficient (ICC), Pearson correlation coefficient (r), mean absolute error (MAE), root mean square error (RMSE), and box plots.

Results

The model's mean differences from the reference standard for LL, SHA, ISA (L4-L5), ISA (L5-S1), PLS (L4-L5), and PLS (L5-S1) were 1.69°, 1.36°, 1.55°, 1.90°, 1.60%, and 2.43%, respectively. When compared with the reference standard, the measurements of the model had better correlation and consistency (LL, SHA, and ISA: ICC = 0.91-0.97, r = 0.91-0.96, MAE = 1.89-2.47, RMSE = 2.32-3.12; PLS: ICC = 0.90-0.92, r = 0.90-0.91, MAE = 1.95-2.93, RMSE = 2.52-3.70), and the differences between them were not statistically significant (p > 0.05).

Conclusion

The model developed in this study could correctly identify key vertebral points on lateral lumbar radiographs and automatically calculate lumbosacral radiographic parameters. The measurement results of the model had good consistency and reliability compared to manual measurements. With additional training and optimization, this technology holds promise for future measurements in clinical practice and analysis of large datasets.

Sagittal spinopelvic alignment in ambulatory persons with cerebral palsy

PURPOSE

This study aimed to describe the spinopelvic alignment of a cohort of young ambulatory individuals with cerebral palsy (CP) and compare it to published spinopelvic alignment data for the typically developing adolescents.

METHODS

Thirty-seven adolescents (18 females) with CP at GMFCS I-III were included in this retrospective case series. Lumbar lordosis and pelvic incidence were measured, and their mismatch was calculated. A model that calculates predicted lumbar lordosis based on pelvic incidence in normative data was utilized to calculate a predicted lumbar lordosis in this cohort with cerebral palsy.

RESULTS

At imaging, ages were mean and standard deviation 13.5 ± 3.0 years. Pelvic incidence was 46.2° ± 12.9°, pelvic tilt was 2.8° ± 9.4°, sacral slope was 43.6° ± 10.8°, and measured lumbar lordosis was 59.4° ± 11.6°. There were no differences in pelvic incidence or lumbar lordosis among the GMFCS levels; however, pelvic incidence was higher in females. Pelvic incidence-lumbar lordosis mismatch greater than 10° was found in 67% of the cohort. Mean predicted lumbar lordosis based on the model was 54.7° ± 8.5°, averaging 8° less than measured lordosis.

CONCLUSION

PI-LL mismatch was identified in 67% of this cohort of ambulatory adolescents with CP, in part due to greater lordosis than predicted by a model based on data from adolescents without CP. The implications of this finding, such as the correlation between sagittal spinopelvic alignment and quality of life in this population, should be assessed further in ambulatory patients with cerebral palsy.

LEVEL OF EVIDENCE

Level IV-retrospective cohort study and literature comparison.

Artificial Intelligence Assistance for the Measurement of Full Alignment Parameters in Whole-Spine Lateral Radiographs

BACKGROUND

Measuring spinal alignment with radiological parameters is essential in patients with spinal conditions likely to be treated surgically. These evaluations are not usually included in the radiological report. As a result, spinal surgeons commonly perform the measurement, which is time-consuming and subject to errors. We aim to develop a fully automated artificial intelligence (AI) tool to assist in measuring alignment parameters in whole-spine lateral radiograph (WSL X-rays).

METHODS

We developed a tool called Vertebrai that automatically calculates the global spinal parameters (GSPs): Pelvic incidence, sacral slope, pelvic tilt, L1-L4 angle, L4-S1 lumbo-pelvic angle, T1 pelvic angle, sagittal vertical axis, cervical lordosis, C1-C2 lordosis, lumbar lordosis, mid-thoracic kyphosis, proximal thoracic kyphosis, global thoracic kyphosis, T1 slope, C2-C7 plummet, spino-sacral angle, C7 tilt, global tilt, spinopelvic tilt, and hip odontoid axis. We assessed human-AI interaction instead of AI performance alone. We compared the time to measure GSP and inter-rater agreement with and without AI assistance. Two institutional datasets were created with 2267 multilabel images for classification and 784 WSL X-rays with reference standard landmark labeled by spinal surgeons.

RESULTS

Vertebrai significantly reduced the measurement time comparing spine surgeons with AI assistance and the AI algorithm alone, without human intervention (3 minutes vs. 0.26 minutes; P < 0.05). Vertebrai achieved an average accuracy of 83% in detecting abnormal alignment values, with the sacral slope parameter exhibiting the lowest accuracy at 61.5% and spinopelvic tilt demonstrating the highest accuracy at 100%. Intraclass correlation analysis revealed a high level of correlation and consistency in the global alignment parameters.

CONCLUSIONS

Vertebrai's measurements can accurately detect alignment parameters, making it a promising tool for measuring GSP automatically.

Clinical and radiographic outcomes following 120 consecutive patients undergoing prone transpsoas lateral lumbar interbody fusion

PURPOSE

The prone transpsoas approach is a single-position alternative to traditional lateral lumbar interbody fusion (LLIF). Earlier prone LLIF studies have focused on technique, feasibility, perioperative efficiencies, and immediate postoperative radiographic alignment. This study was undertaken to report longer-term clinical and radiographic outcomes, and to identify learnings from experiential evolution of the prone LLIF procedure.

METHODS

All consecutive patients undergoing prone LLIF for any indication at one institution were included (n = 120). Demographic, diagnostic, treatment, and outcomes data were captured via prospective institutional registry. Retrospective analysis identified 31 'pre-proceduralization' and 89 'post-proceduralization' prone LLIF approaches, enabling comparison across early and later cohorts.

RESULTS

187 instrumented LLIF levels were performed. Operative time, retraction time, LLIF blood loss, and hospital stay averaged 150 min, 17 min, 50 ml, and 2.2 days, respectively. 79% of cases were without complication. Postoperative hip flexion weakness was identified in 14%, transient lower extremity weakness in 12%, and sensory deficits in 10%. At last follow-up, back pain, worst-leg pain, Oswestry, and EQ-5D health state improved by 55%, 46%, 48%, and 51%, respectively. 99% improved or maintained sagittal alignment with an average 6.5° segmental lordosis gain at LLIF levels. Only intra-psoas retraction time differed between pre- and post-proceduralization; proceduralization saved an average 3.4 min/level (p = 0.0371).

CONCLUSIONS

The largest single-center prone LLIF experience with the longest follow-up to-date shows that it results in few complications, quick recovery, improvements in pain and function, high patient satisfaction, and improved sagittal alignment at an average one year and up to four years postoperatively.