Adult Spinal Deformity: Epidemiology, Health Impact, Evaluation, and Management

Use of Supplemental Rod Constructs in Adult Spinal Deformity Surgery: A Review

Adult spinal deformity comprises a heterogeneous group of disorders that primarily affects older patients and can have a significant negative affect on health-related quality of life. Operative treatment for adult spinal deformity typically entails posterior instrumented fusions that have demonstrated the potential to significantly improve health-related quality of life outcomes. However, until fusion is achieved, the instrumentation providing structural support is subject to repetitive cyclical loading that disproportionately fatigues high-stress areas and can result in instrumentation failure. Despite considerable advances in surgical fixation techniques and technology, pseudarthrosis with subsequent implant failure still poses a challenge for surgeons and continues to be 1 of the most common complications, leading to revision surgery. The addition of supplemental rods to primary constructs has gained widespread popularity to mitigate implant failure. Theoretically, more rods will add stiffness, stability, and decreased surface strain, which will provide longer instrumentation lifespan to allow for osseous fusion. There is significant heterogeneity in these constructs, and different types of supplemental rods (eg, satellite, accessory, delta rods, "kickstand rod," and "iliac accessory rod") can be used independently or in combination to further increase strength. However, the use of supplemental rods may increase the rate of proximal junctional kyphosis/failure and paradoxically diminish anterior column fusion rates. Hence, indications and optimal configurations are still a matter of debate. The aim of this narrative review is to provide an overview of the supplemental rod constructs described in the literature and focus on the current evidence supporting their indications and potential impact.

Male patients with adult spinal deformity: sex differences in demographics, radiography, and complications

PURPOSE

This study aimed to investigate sex-related differences in demographics, radiography, and perioperative complications in adult spinal deformity (ASD) surgeries.

METHODS

This retrospective cohort, single-center study enrolled patients who underwent long-instrumented fusion from the thoracic spine to the ilium for ASD, with a minimum follow-up of 2 years. The incidence of preoperative comorbidities, perioperative complications, and postoperative mechanical complications was analyzed.

RESULTS

Of the 323 patients, ASD was more common in females (85.8%). The T-score in female patients was lower than that in male patients (-1.6 ± 1.1 vs.- 0.8 ± 1.0, p = 0.02). Male patients demonstrated lower rates of degenerative kyphoscoliosis (83.4% vs. 65.2%, p = 0.004) but higher rates of neuromuscular disease (7.6% vs. 21.7%, p = 0.003) than female patients. Male patients exhibited higher prevalence of cardiovascular disease (4.0% vs. 13.5%, p = 0.034) and hemodialysis (2.5% vs. 10.8%, p = 0.035). Additionally, male patients had a higher Charlson Comorbidity Index than female patients (0.8 ± 1.1 vs. 1.4 ± 1.1, p = 0.001). Moreover, male patients showed higher perioperative complications in surgical site infection (5.1% vs. 15.2%, p = 0.018). However, the incidence of proximal junctional failure (43.3% vs. 39.1%, p = 0.595) and rod fracture (27.8% vs. 26.1%, p = 0.81) was not different.

CONCLUSIONS

Male patients with ASD demonstrated frequent pathology of neuromuscular disease, preoperative comorbidities, and surgical site infection, necessitating careful preoperative checkups and intraoperative care.

Long-term reoperation risk of thoracic to pelvis instrumentation for spinal deformity: a longitudinal study of 7,062 patients

PURPOSE

To perform a large-scale assessment of reoperation risk among spine deformity patients undergoing thoracic to pelvis surgery.

METHODS

The PearlDiver database was queried for spinal deformity patients (scoliosis, kyphosis, spondylolisthesis, sagittal plane deformity) undergoing at minimum, a T12-pelvis operation (2010-2020). CPT codes identified lumbar arthrodesis procedures that included pelvic fixation and ≥ 7 levels of posterior instrumentation on the same day. Minimum follow-up was 2 years. Reoperations included subsequent arthrodesis, decompression, osteotomy, device insertion, and pelvic fixation procedures. Multivariable regression analysis described associations between variables and reoperation risk.

RESULTS

7,062 patients met criteria. Overall reoperation rate was 23.2%. Reoperation rate at 2- and 5-year was 16.9% and 22.1% respectively. 10-year reoperation-free probability was 73.7% (95% CI: 72.4-74.9%). Multivariable analysis revealed higher reoperation risk for patients with kyphosis and ≥ 13 levels of posterior instrumentation. Patients who received interbody cages had a lower reoperation risk. No association was found between the presence or absence of osteotomy procedures and reoperation risk. Lastly, linear regression analyses revealed no significant relationship between age or ECI and risk for subsequent operations did not independently influence reoperation.

CONCLUSIONS

This study, representing a real-world cohort of over six times the largest current prospective data set, found a 2-year reoperation rate of 17%, similar to previous studies, suggesting study group findings are applicable to a broader population. Preoperative kyphosis and ≥ 13 levels of posterior instrumentation was associated with higher reoperation risk, while the use of interbody cages was protective. Age, medical comorbidities, and osteotomies did not predict reoperations.

Combined anterior-posterior versus posterior only approach for surgical management of adult spinal deformity: a systematic review and meta-analysis of comparative studies

PURPOSE

The purpose of this systematic review and meta-analysis was to examine the clinical outcomes and complication rates for fusion procedures of adult spinal deformity (ASD) performed via an anterior-posterior approach as compared to a posterior-only approach to guide surgical decision-making. Numerous surgical techniques exist for operative management of ASD; however, no systematic review and meta-analysis exists comparing combined anterior-posterior approaches to posterior-only approach, despite significant interest in the current literature.

METHODS

Four databases were used to collect articles from database inception until September 9th, 2023. Inclusion criteria was articles that examined both anterior-posterior or posterior only surgical approach, adult patients, comparative studies, and articles in English.

RESULTS

Seven comparative articles met the inclusion criteria. Included patients had a frequency weighted (FW) mean age of 60.2 ± 5.1 years and a FW mean follow-up of 40.4 ± 12.5 months. Qualitative data did not favor either group in terms of length of stay, radiographic outcomes, or functional outcomes. There was a total of 306 complications in the Anterior-Posterior group with a complication rate per patient of 1.0 ± 0.9 complications whereas there was a total of 380 complications in the Posterior Only group with a complication rate per patient of 1.0 ± 1.2 complications. Meta-analysis of specific complications found no significant difference in revision rate, dural tear rate, neurological complication rate, infection rate, or pseudoarthrosis rate.

CONCLUSION

Surgical management for ASD may provide comparable results in terms of surgical parameters, radiographic outcomes, functional outcomes, and complication rates, irrespective of surgical approach.

Psychological distress does not predict decisional regret in patients undergoing spinal reconstruction for adult spinal deformity

PURPOSE

The study aimed to assess the link between preoperative psychological distress and postoperative decisional regret in adult spinal deformity (ASD) surgery patients. We hypothesized that greater pre-surgery distress would correlate with higher post-surgery regret. This evaluation was based on a retrospective case series from an institution with standardized surgical guidelines for ASD.

METHODS

This IRB-approved retrospective study analyzed our institution's ASD database from 2014 to 2020. Eligible patients had a minimum two-year post-op follow-up and preoperative psychological distress assessment. Patients were grouped based on psychological distress levels: green, yellow, and yellow minus. Regret post-surgery was assessed using the Decision Regret Scale and SRS-22 Question 22. Logistic regression evaluated the impact of distress levels on regret, controlling for age and sex.

RESULTS

Out of 167 eligible patients, 112 responded and were analyzed. No significant demographic differences were observed between responders and non-responders. Using the Decision Regret Scale, 41% expressed no regret, while 63% expressed no regret with the SRS-22 questionnaire's Single-Item scale. Only the yellow minus group showed significant regret difference based on osteotomy, with non-recipients more likely to express regret.

CONCLUSION

This study found no significant link between psychological distress and post-operative regret in adult spinal deformity surgery after a minimum 2-year follow-up. Although nearly 60% exhibited some post-surgery regret, predicting regret based on psychological burden or demographics remains challenging. Further research is essential to identify factors contributing to post-operative regret in spinal deformity surgery patients.

Clinical outcomes of percutaneous transforaminal endoscopic decompression for the treatment of degenerative lumbar scoliosis associated with spinal stenosis in elderly individuals: a matched comparison study

PURPOSE

This retrospective cohort study evaluated the efficacy and safety of percutaneous transforaminal endoscopic decompression (PTED) in elderly patients with degenerative lumbar scoliosis (DLS) associated with lumbar spinal stenosis (LSS).

STUDY DESIGN

A matched comparison study.

METHODS

In total, 97 patients with DLS associated with LSS who underwent PTED under local anesthesia between 2016 and 2021 were retrospectively analyzed. Using the inclusion and exclusion criteria, 24 patients aged ≥ 80 years were screened and included in the study group. Then, 24 patients aged 50-80 years were matched according to gender, date of surgery, and surgical levels were included in the control group. Clinical outcomes such as the visual analog scale (VAS) score, Oswestry Disability Index (ODI) score, modified MacNab criteria, radiological parameters, and complications were assessed. The independent sample t-test, Pearson's chi-square test and Fisher's exact test were used to compare the parameters between the study and control groups.

RESULTS

The study group had significantly higher mean American Society of Anesthesiologists classification and age-adjusted Charlson Comorbidity Index scores than the control group (2.42 ± 0.72) vs. 5.25 ± 1.03 and 1.67 ± 0.76 vs. 3.17 ± 2.10, respectively). The VAS scores for pain in two legs and back and ODI scores significantly improved at two weeks after surgery and at the final followup (p < 0.05). The study group had higher back pain VAS and ODI scores than the control group at the final followup (p < 0.05). In addition, the complication and patient satisfaction rates were similar between the two groups (p > 0.05). The overall radiological parameters were comparable between the two groups, and there was no significant deterioration in coronal imbalance or loss of disc height between the two groups.

CONCLUSION

Elderly patients (aged ≥ 80 years) with DLS associated with LSS are less fit and have a greater number of comorbidities. However, they can achieve satisfactory outcomes with PTED, which are comparable to those of patients < 80 years. PTED under local anesthesia can also be an efficient alternative to conventional open lumbar decompression surgery for treating elderly patients with comorbidities.

Surgical Management of Adult Spinal Deformity Patients with Osteoporosis

Adult spinal deformity (ASD) commonly affects older adults, with up to 68% prevalence in those over 60, and is often complicated by osteoporosis, which reduces bone mineral density (BMD) and increases surgical risks. Osteoporotic patients undergoing ASD surgery face higher risks of complications like hardware failure, pseudoarthrosis, and proximal junctional kyphosis (PJK). Medical management with antiresorptive medications (e.g., bisphosphonates, SERMs, and denosumab) and anabolic agents (e.g., teriparatide, abaloparatide, and romosozumab) can improve BMD and reduce complications. While bisphosphonates reduce fracture risk, teriparatide and newer agents like romosozumab show promise in increasing bone density and improving fusion rates. Surgical adaptations such as consideration of age-adjusted alignment, fusion level selection, cement augmentation, and the use of expandable screws or tethers enhance surgical outcomes in osteoporotic patients. Specifically, expandable screws and cement augmentation have been shown to improve fixation stability. However, further research is needed to evaluate the effectiveness of these treatments, specifically in osteoporotic ASD patients.

Proximal junctional kyphosis above long spinal fusions

INTRODUCTION

Spinal deformity in adults is a major public health problem. After failure of conservative treatment, correction and fusion surgery leads to clinical and radiological improvement. However, mechanical complications and more particularly - proximal junctional kyphosis (PJK) - are common with an incidence of 10%-40% depending on the studies.

ANALYSIS

Several risk factors have been identified and can be grouped into three categories. Among the patient-related factors, advanced age, comorbidities, osteoporosis and sarcopenia play a determining role. Among the radiological factors, changes in sagittal alignment (cranial migration of thoracolumbar inflection point, over-correction of lumbar hyperlordosis, preoperative thoracolumbar kyphosis) play a key role. Finally, the fusion technique itself may increase the risk of PJK (use of screws instead of hooks) as a surgical factor.

PREVENTION

Prevention happens at each phase of treatment. A patient assessment is done preoperatively to identify those at risk of PJK. Treating osteoporosis is beneficial. The surgical strategy must also be adapted: the choice of transitional implants such as sublaminar links or hooks and the use of ligament reinforcement techniques can help minimize the risk of PJK. Finally, methodical clinical and radiological follow-up will help to detect early signs of PJK and allow a surgeon to reoperate right away.

TREATMENT

Not all PJK requires surgical revision. Radiological monitoring and functional treatment is sometimes sufficient. However, if the patient develops pain, neurological complications or instability detected by imaging (unstable fracture, spondylolisthesis, spinal cord compression), revision surgery is necessary. It may consist of proximal extension of the fusion combined with decompression of the stenosis levels at a minimum.

CONCLUSION

PJK is a major challenge for surgeons. The best treatment is prevention, with a thorough analysis of risk factors leading to a well-planned and personalized surgery. Regular postoperative follow-up is essential.

LEVEL OF EVIDENCE

Expert opinion.

Glycemic laboratory values are associated with increased length of stay and 90-day revision risk following surgical management of adult spinal deformity

BACKGROUND CONTEXT

Diabetes mellitus (DM) is a common comorbidity among patients undergoing spinal fusion for adult spinal deformity (ASD) surgery. An elevated Hemoglobin A1c (HbA1c) and elevated postoperative glucose have been shown to increase the risk of complications following spine and other orthopedic surgeries; however, data is limited for ASD.

PURPOSE

To investigate glycemic control and ASD surgery to inform surgical decision making, medical optimization, and patient education.

STUDY DESIGN/SETTING

Retrospective cohort.

PATIENT SAMPLE

Total of 106 adult patients undergoing surgical correction for ASD with an HbA1c drawn within 6 months preoperatively or 2 weeks postoperatively and valid plasma glucose levels throughout postoperative hospital stay.

OUTCOME MEASURES

Length of stay, 90-day wound complication, 90-day readmission, 90-day revision.

METHODS

All patients undergoing spinal fusion of seven or more levels between 2021 and 2023 at two large academic medical centers were identified using institutional data acquisition software. Medical charts were then manually reviewed to obtain and confirm demographic, laboratory, and surgical characteristics and outcomes. Laboratory characteristics included preoperative HbA1c, mean postoperative glucose (PG), and maximum PG. Surgical characteristics and outcomes included procedure time, estimated blood loss (EBL), length of inpatient stay (LOS), transfusion requirement, 90-day complications, 90-day revision, and 90-day readmission. Bivariate analysis was performed followed by simple and multiple regression analysis. Odds ratios were established relative to the laboratory threshold values informed by receiver operating characteristics.

RESULTS

Of 872 original procedures identified, 106 patients (12.2%) were adults with preoperative HbA1c and postoperative plasma glucose measurements who underwent surgery for a diagnosis of ASD. Median patient age was 67 years (IQR 59-72 years), 59 (55.7%) were female, and 96 (90.6%) were of Caucasian race. Median LOS was 7 days (IQR 5-10 years) and median HbA1c was 5.9% (IQR 5.3%-6.5%). Higher preoperative HbA1c was correlated with increased LOS (R=0.22, p=.023). The odds ratio for patients requiring extended LOS was 2.49 (95% CI 1.06-5.86, p=.034) for those with HbA1c ≥6.3%. Multiple regression analysis of LOS identified HbA1c [B= 1.51 (95% CI 0.32-2.70), p=.013] as a positive predictor of LOS and mean PG [B= -0.05 (95% CI -0.10 to (-0.01)), p=.019] as a weakly negative predictor of LOS. Upon simple logistic regression, the odds ratio for 90-day revision was 1.81 (95% CI 1.02-3.19, p=.042) for every unit increase in HbA1c. Patients with mean PG ≥165 mg/dL [OR=5.76 (95% CI 1.28-26.01), p=.024] were at increased risk for 90-day revision. Glycemic laboratory values do not seem to predict 90-day wound complications or 90-day readmission following surgery for ASD.

CONCLUSION

Elevated preoperative HbA1c is associated with increased LOS and risk for revision within 90 days of ASD surgery. Postoperative hyperglycemia is also associated with increased 90-day revision risk. To our knowledge, this study is the first to evaluate HbA1c and outcomes following ASD surgery. These findings can be leveraged to inform preoperative medical optimization and highlight the importance of glycemic control in ASD patients undergoing corrective surgical intervention.

Identification and impact of failure of pelvic compensation in patients with adult spinal deformity

BACKGROUND CONTEXT

Previous research has identified a specific subtype known as failure of pelvic compensation (FPC) in patients with adult spinal deformity (ASD). However, the criteria for assessing FPC remain inconsistent, and its impacts on spinal sagittal alignment and health-related quality-of-life (HRQoL) scores remain unclear.

PURPOSE

To propose a novel criterion for identifying FPC based on variations in spinopelvic alignment during the transition from the supine to upright position and to evaluate the effects of FPC on patients' spinal sagittal alignment and HRQoL scores.

STUDY DESIGN/SETTING

Retrospective cross-sectional study.

PATIENT SAMPLE

Patients with ASD from a monocenter database.

OUTCOME MEASURES

Radiographic measures, including thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt, pelvic incidence (PI), and sagittal vertical axis (SVA), were measured on lateral whole-spine radiographs. LL and SS were also measured on reconstructed lumbar computed tomography images in the sagittal view taken in the supine position. The relative functional cross-sectional area (rFCSA) of paraspinal muscles was evaluated via lumbar magnetic resonance imaging. HRQoL measures, encompassing visual analog scale for back pain (VAS-BP), Oswestry Disability Index (ODI), and Scoliosis Research Society-22R (SRS-22R), were collected.

METHODS

A total of 154 patients were enrolled. Based on the calculated minimum detectable change of SS, FPC was defined as the change in SS of less than 3.4° between supine and upright positions. Patients were divided into 3 groups: sagittal balance with pelvic compensation (SI-PC), sagittal imbalance with pelvic compensation (SI-PC), and sagittal imbalance with failure of pelvic compensation (SI-FPC). Radiographic parameters and HRQoL scores were compared among the groups.

RESULTS

Thirty-six patients were categorized into the SB-PC group, 87 into the SI-PC group, and 31 into the SI-FPC group. Patients with low PI and small paraspinal muscles rFCSA were more prone to experiencing FPC accompanied by severe sagittal imbalance. The SI-FPC group exhibited less TK and a larger SS than the SI-PC group exhibited and had a similar SVA as that of the SI-PC group. Additionally, they displayed worse VAS-BP, ODI, SRS-function, and SRS-22 total scores than the SB-PC group displayed.

CONCLUSIONS

In patients with ASD, an inherently low pelvic compensatory reserve and a high fatty infiltration in paraspinal muscles are pivotal factors contributing to FPC. Compared with SI-PC patients, SI-FPC patients demonstrate a thoracic-dominant compensatory pattern for sagittal malalignment. In addition, these patients experienced more severe pain and functional decline than the SB-PC patients experienced.

Staged Versus Same-Day Surgery in Circumferential Minimally Invasive Deformity Correction

BACKGROUND AND OBJECTIVES

We sought to compare long-term clinical and radiographic outcomes in patients who underwent staged vs same-day circumferential minimally invasive surgery (cMIS) for adult spinal deformity (ASD).

METHODS

We reviewed staged and same-day cMIS ASD cases in a prospective multi-institution database to compare preoperative and 2-year clinical and radiographic parameters between cohorts.

RESULTS

A total of 85 patients with a 2-year follow-up were identified (27 staged, 58 same-day). Staged patients had more extensive surgeries and greater hospital length of stay (all P < .001). There were no significant differences in preoperative or 2-year postoperative clinical metrics between cohorts. Patients in the staged cohort also had greater preoperative coronal deformity and thus experienced greater reduction in coronal deformity at 2 years (all P < .01).

CONCLUSION

Patients undergoing staged or same-day cMIS correction had similar outcomes at 2 years postoperatively. Staged cMIS ASD correction may be more appropriate in patients with greater deformity, higher frailty, and who require longer, more extensive surgeries.

Contemporary utilization of three-column osteotomy techniques in a prospective complex spinal deformity multicenter database: implications on full-body alignment and perioperative course

BACKGROUND

Research has focused on the increased correction from a three-column osteotomy (3CO) during adult spinal deformity (ASD) surgery. However, an in-depth analysis on the performance of a 3CO in a cohort of complex spinal deformity cases has not been described.

STUDY DESIGN/SETTING

This is a retrospective study on a prospectively enrolled, complex ASD database.

PURPOSE

This study aimed to determine if three-column osteotomies demonstrate superior benefit in correction of complex sagittal deformity at the cost of increased perioperative complications.

METHODS

Surgical complex adult spinal deformity patients were included and grouped into thoracolumbar 3COs compared to those who did not have a 3CO (No 3CO) (remaining cohort). Rigid deformity was defined as ΔLL less than 33% from standing to supine. Severe deformity was defined as global (SVA > 70 mm) or C7-PL > 70 mm, or lumbopelvic (PI-LL > 30°). Means comparison tests assessed correction by 3CO grade/location. Multivariate analysis controlling for baseline deformity evaluated outcomes up to six weeks compared to No 3CO.

RESULTS

648 patients were included (Mean age 61 ± 14.6 years, BMI 27.55 ± 5.8 kg/m2, levels fused: 12.6 ± 3.8). 126 underwent 3CO, a 20% higher usage than historical cohorts. 3COs were older, frail, and more likely to undergo revision (OR 5.2, 95% CI [2.6-10.6]; p < .001). 3COs were more likely to present with both severe global/lumbopelvic deformity (OR 4), 62.4% being rigid. 3COs had greater use of secondary rods (OR 4st) and incurred 4 times greater risk for: massive blood loss (> 3500 mL), longer LOS, SICU admission, perioperative wound and spine-related complications, and neurologic complications when performed below L3. 3COs had similar HRQL benefit, but higher perioperative opioid use. Mean segmental correction increased by grade (G3-21; G4-24; G5-27) and was 4 × greater than low-grade osteotomies, especially below L3 (OR 12). 3COs achieved 2 × greater spinopelvic correction. Higher grades properly distributed lordosis 50% of the time except L5. Pelvic compensation and non-response were relieved more often with increasing grade, with greater correction in all lower extremity parameters (p < .01). Due to the increased rate of complications, 3COs trended toward higher perioperative cost ($42,806 vs. $40,046, p = .086).

CONCLUSION

Three-column osteotomy usage in contemporary complex spinal deformities is generally limited to more disabled individuals undergoing the most severe sagittal and coronal realignment procedures. While there is an increased perioperative cost and prolongation of length of stay with usage, these techniques represent the most powerful realignment techniques available with a dramatic impact on normalization at operative levels and reciprocal changes.

Characteristics of sagittal spinopelvic alignment in Thai population: a cross-sectional study

BACKGROUND

The prevalence of spinal deformity is a significant health concern often associated with the aging process. It is primarily attributed to the thickening of spinal joints, ligament pathologies, or the narrowing of the spinal canal, leading to compression of the spinal cord and nerve roots, and subsequently causing musculoskeletal problems. When considering corrective surgery for adult spinal deformities, it is crucial for spine surgeons to take into account the standard values of sagittal spinopelvic alignment. Notably, there is currently a lack of specific data on this aspect within the Thai population. Therefore, our study was focused on evaluating the alignment in the Thai population.

OBJECTIVES

To analyze sagittal spinopelvic alignment parameters in the asymptomatic Thai population and compare them with other populations.

MATERIALS AND METHODS

This study was designed as a cross-sectional analysis involving 194 participants, wherein the sagittal spinopelvic parameters were evaluated utilizing radiographic images. The measurements of the sagittal vertical axis (SVA), pelvic incidence (PI), lumbar lordosis (LL), sacral slope (SS), and pelvic tilt (PT) were determined by averaging the assessments conducted by two orthopedic residents and a spine surgeon. In addition, participants' demographic information was obtained through questionnaires, and further analysis was performed on age, gender, and body mass index data. The study also encompassed the determination of correlations between various parameters and the comparison of these parameters with other populations.

RESULTS

The body mass index (BMI) of the study participants demonstrated significant associations with several spinal parameters. Specifically, BMI showed significant correlations with sagittal vertical axis (SVA) (r = 0.2, p = 0.09), pelvic incidence (PI) (r = 0.4, p < 0.01), lumbar lordosis (LL) (r = 0.2, p = 0.02), sacral slope (SS) (r = -0.2, p = 0.02), and pelvic tilt (PT) (r = 0.2, p = 0.02). The SS exhibited a statistically significant decline with increasing age (p = 0.04). Furthermore, the mean SVA, PI, LL, SS, and PT differed significantly between the study participants and the Indian population. In addition, the SS was notably lower when compared to the European population.

CONCLUSION

The study revealed the spinopelvic parameters in a cohort of healthy Thai population and observed a correlation between their body mass index (BMI) and pelvic incidence (PI), lumbar lordosis (LL), sacral slope (SS), and pelvic tilt (PT). Notably, the average SS among Thai adults was found to be statistically lower than that of individuals from Indian, European Caucasian, Asian, and Mexican populations. These insights hold potential value as a reference when strategizing surgical interventions for Thai patients with spinal deformities.

Unsupervised Clustering of Adult Spinal Deformity Patterns Predicts Surgical and Patient-Reported Outcomes

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To evaluate whether different radiographic clusters of adult spinal deformity identified using artificial intelligence-based clustering are associated with distinct surgical outcomes.

METHODS

Patients were classified based on the results of a previously conducted analysis that examined clusters of deformity, including Moderate Sagittal (Mod Sag), Severe Sagittal (Sev Sag), Coronal, and Hyper-Thoracic Kyphosis (Hyper-TK). The surgical data, HRQOL, and complication outcomes of these clusters were then compared.

RESULTS

The final analysis included 1062 patients. Similar to published results on a different patient sample, Mod Sag and Sev Sag patients were older, more likely to have a history of previous spine surgery, and more disabled. By 2-year, all clusters improved in HRQOL and reached a similar rate of minimal clinically important difference (MCID).The Sev Sag cluster had the highest rate major complications (53% vs 34-40%), and complications leading to reoperation (29% vs 17-23%), implant failures (20% vs 8-11%), and operative complications (27% vs 10-17%). Coronal patients had the highest rate of pulmonary complications (9% vs 3-6%) but the lowest rate of X-ray imbalance (10% vs 19-21%). No significant differences were found in neurological complications, infection rate, gastrointestinal, or cardiac events (all P > .1). Kaplan-Meier survival curves demonstrated a lower time to first complications for the Sev Sag cluster.

CONCLUSIONS

All clusters of adult spinal deformity benefit similarly from surgery as they all achieved similar rates of MCID. Although the rates of complications varied among the clusters, the types of complications were not significantly different.

AM-PAC Mobility Score <13 Predicts Development of Ileus Following Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective review.

OBJECTIVE

To determine whether the Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" score is associated with the development of postoperative ileus.

SUMMARY OF BACKGROUND DATA

Adult spinal deformity (ASD) surgery has a high complication rate. One common complication is postoperative ileus, and poor postoperative mobility has been implicated as a modifiable risk factor for this condition.

METHODS

Eighty-five ASD surgeries in which ≥5 levels were fused were identified in a single institution database. A physical therapist/physiatrist collected patients' daily postoperative AM-PAC scores, for which we assessed first, last, and daily changes. We used multivariable linear regression to determine the marginal effect of ileus on continuous AM-PAC scores; threshold linear regression with Bayesian information criterion to identify a threshold AM-PAC score associated with ileus; and multivariable logistic regression to determine the utility of the score thresholds when controlling for confounding variables.

RESULTS

Ten of 85 patients (12%) developed ileus. The mean day of developing ileus was postoperative day 3.3±2.35. The mean first and last AM-PAC scores were 16 and 18, respectively. On bivariate analysis, the mean first AM-PAC score was lower in patients with ileus than in those without (13 vs. 16; P< 0.01). Ileus was associated with a first AM-PAC score of 3 points lower (Coef. -2.96; P< 0.01) than that of patients without ileus. Patients with an AM-PAC score<13 had 8 times greater odds of developing ileus ( P= 0.023). Neither the last AM-PAC score nor the daily change in AM-PAC score was associated with ileus.

CONCLUSIONS

In our institutional cohort, a first AM-PAC score of <13, corresponding to an inability to walk or stand for more than 1 minute, was associated with the development of ileus. Early identification of patients who cannot walk or stand after surgery can help determine which patients would benefit from prophylactic management.

LEVEL OF EVIDENCE

Level-III.

Impact of Controlled Versus Uncontrolled mFI-5 Frailty on Perioperative Complications After Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective review.

OBJECTIVES

We substratified the mFI-5 frailty index to reflect controlled and uncontrolled conditions and assess their relationship to perioperative complications.

SUMMARY OF BACKGROUND DATA

Risk assessment before adult spinal deformity (ASD) surgery is critical because the surgery is highly invasive with a high complication rate. Although frailty is associated with risk of surgical complications, current frailty measures do not differentiate between controlled and uncontrolled conditions.

METHODS

Frailty was calculated using the mFI-5 index for 170 ASD patients with fusion of ≥5 levels. Uncontrolled frailty was defined as blood pressure >140/90 mm Hg, HbA1C >7% or postprandial glucose >180 mg/dL, or recent chronic obstructive pulmonary disease (COPD) exacerbation, while on medication. Patients were divided into nonfrailty, controlled frailty, and uncontrolled frailty cohorts. The primary outcome measure was perioperative major and wound complications. Bivariate analysis was performed. Multivariable analysis assessed the relationship between frailty and perioperative complications.

RESULTS

The cohorts included 97 nonfrail, 54 controlled frail, and 19 uncontrolled frail patients. Compared with nonfrail patients, patients with uncontrolled frailty were more likely to have age older than 60 years (84% vs. 24%), hyperlipidemia (42% vs. 20%), and Oswestry Disability Index (ODI) score >42 (84% vs. 52%) ( P <0.05 for all). Controlled frailty was associated with those older than 60 years (41% vs. 24%) and hyperlipidemia (52% vs. 20%) ( P <0.05 for all). On multivariable regression analysis controlling for hyperlipidemia, functional independence, motor weakness, ODI>42, and age older than 60 years, patients with uncontrolled frailty had greater odds of major complications (OR 4.24, P =0.03) and wound complications (OR 9.47, P =0.046) compared with nonfrail patients. Controlled frailty was not associated with increased risk of perioperative complications ( P >0.05 for all).

CONCLUSIONS

Although patients with uncontrolled frailty had higher risk of perioperative complications compared with nonfrail patients, patients with controlled frailty did not, suggesting the importance of controlling modifiable risk factors before surgery.

LEVEL OF EVIDENCE

3.

Mechanisms of lumbar spine "flattening" in adult spinal deformity: defining changes in shape that occur relative to a normative population

PURPOSE

Previous work comparing ASD to a normative population demonstrated that a large proportion of lumbar lordosis is lost proximally (L1-L4). The current study expands on these findings by collectively investigating regional angles and spinal contours.

METHODS

119 asymptomatic volunteers with full-body free-standing radiographs were used to identify age-and-PI models of each Vertebra Pelvic Angle (VPA) from L5 to T10. These formulas were then applied to a cohort of primary surgical ASD patients without coronal malalignment. Loss of lumbar lordosis (LL) was defined as the offset between age-and-PI normative value and pre-operative alignment. Spine shapes defined by VPAs were compared and analyzed using paired t-tests.

RESULTS

362 ASD patients were identified (age = 64.4 ± 13, 57.1% females). Compared to their age-and-PI normative values, patients demonstrated a significant loss in LL of 17 ± 19° in the following distribution: 14.1% had "No loss" (mean = 0.1 ± 2.3), 22.9% with 10°-loss (mean = 9.9 ± 2.9), 22.1% with 20°-loss (mean = 20.0 ± 2.8), and 29.3% with 30°-loss (mean = 33.8 ± 6.0). "No loss" patients' spine was slightly posterior to the normative shape from L4 to T10 (VPA difference of 2°), while superimposed on the normative one from S1 to L2 and became anterior at L1 in the "10°-loss" group. As LL loss increased, ASD and normative shapes offset extended caudally to L3 for the "20°-loss" group and L4 for the "30°-loss" group.

CONCLUSION

As LL loss increases, the difference between ASD and normative shapes first occurs proximally and then progresses incrementally caudally. Understanding spinal contour and LL loss location may be key to achieving sustainable correction by identifying optimal and personalized postoperative shapes.

Long term mechanical failure in well aligned adult spinal deformity patients

BACKGROUND CONTEXT

Mechanical complications (MC) are frequently linked to suboptimal postoperative alignment and represent a primary driver of revision surgery in the context of Adult Spinal Deformity (ASD). However, it's worth noting that even among those deemed "well aligned," the risk of experiencing MCs persists, hinting at the potential influence of factors beyond alignment.

PURPOSE

The aim was to assess the incidence of MCs among well-aligned patients and delving into the relevant risk factors and surgical outcomes that come into play within this specific subgroup.

STUDY DESIGN/SETTING

A retrospective analysis was conducted using data from a prospective multicenter database dedicated to ASD.

PATIENT SAMPLE

The study focused on patients aged 55 years or older, who had a minimum follow-up period of 2 years, and exhibited a Global Alignment and Proportion (GAP) score of 2 points or less (excluding age) within 6 weeks of their index surgery.

OUTCOME MEASURES

Mechanical complications such as rod fractures, pseudarthrosis, or junctional kyphosis or failure, METHODS: Patients who developed mechanical complications were identified. Comparative analyses were performed, encompassing both continuous and categorical variables. Furthermore, binary logistic regression tests were employed to pinpoint risk factors, and ROC curves were used to determine the optimal threshold values for these variables.

RESULTS

A total of 83 patients met the inclusion criteria for this study, with a mean age of 66 years. On average, they had 10 instrumented levels, and 77% of them had fusion extending to the pelvis. Additionally, 27% of the patients had undergone 3-column osteotomies (3-CO). Among them, 33 patients (40%) experienced at least 1 MC during an average follow-up period of 4 years, which included 14 cases of proximal junctional kyphosis (PJK) and 20 cases of nonunion or rod breakage. 15 patients (18%) required revision surgery specifically for MC. In univariable analyses, patients who developed MC were characterized by higher body weight, poorer baseline general health (as indicated by worse SF-36 scores), and less favorable preoperative coronal and sagittal alignment. They also had longer hospital stays, a greater number of instrumented levels, and achieved less favorable postoperative coronal and sagittal alignment. Interestingly, factors such as 3-column osteotomies, postoperative bracing, and the addition of an anterior approach did not significantly alter the risk of MC in well-aligned adult spinal deformity (ASD) patients. Binary regression models revealed that independent risk factors for MC included the residual coronal lumbosacral curve, the number of instrumented levels, and Relative Spinopelvic Alignment (RSA). ROC curves identified an optimal threshold of a residual lumbosacral curve of ≤4° and RSA of ≤3°. Moreover, the rate of MCs showed a stepwise increase within the GAP-Proportioned group, with rates of 31% for GAP=0, 54% for GAP=1, and 75% for GAP=2, with RSA emerging as the most influential parameter. Lastly, patients with MC exhibited poorer functional and radiological outcomes at their last follow-up assessment.

CONCLUSIONS

The rate of MCs remains elevated in sagittally "well-aligned" ASD patients that can be attributed to suboptimal residual sagittal and coronal malalignment, which in turn leads to poorer functional outcomes. This study reaffirms the multifaceted nature of MCs and underscores the significance of achieving impeccable postoperative alignment, particularly in the presence of additional risk factors such as extensive surgical correction, a high lever arm (involving instrumented vertebrae), excessive body weight, and frailty (as indicated by SF-36 scores).

Anterior Lumbar Interbody Fusion as a Supplement to Posterior Instrumentation in Adult Spinal Deformity Patients: A Pilot Randomized Study With a Median of Eight Years of Follow-Up

Aim We aim to assess the long-term revision rates in patients with adult spinal deformity (ASD) undergoing posterior instrumentation with or without supplemental anterior lumbar interbody fusion (ALIF) with a median of eight years of follow-up. Materials and methods Based on a previous pilot randomized controlled trial (RCT) from 2012, all previous participants were invited to a clinical and radiographic follow-up. Full medical records from the total cohort were reviewed from the time of operation to the follow-up, and information on revision surgery due to mechanical failure was obtained and compared between the groups. Results Of the original 17 patients included in the RCT, 15 were available for follow-up and 10 attended the clinical and radiographic examination. A retrospective review was performed of the entire original cohort. The median age at follow-up was 67 (61-71) years, and the median follow-up time was 7.7 (5.1-8.8) years. Revision rates among ALIF patients were three out of seven (43%) and eight out of 10 (80%) among non-ALIF patients with pseudoarthrosis and rod breakage being the main cause. Time to failure was longer in ALIF patients with a median of 47 (28-53) months compared with non-ALIF patients with a median of 26 (9-31) months. Conclusion This study revealed a lower rate of revision surgery and a longer time to failure in patients undergoing ASD surgery with supplemental ALIF compared with posterior instrumentation alone. Further studies with a larger sample size are needed to make conclusions on the effect of a supplemental ALIF to posterior instrumentation on lowering the risk of mechanical failure in patients with adult spinal deformity.

Distal Junctional Failure: A Feared Complication of Multilevel Posterior Spinal Fusions

Objectives: Distal junctional failure (DJF) is less commonly described than proximal junctional failure following posterior spinal fusion, and particularly adult spinal deformity (ASD) surgery. We describe a case series of patients with DJF, taking into account sagittal spinopelvic alignment, and suggest potential risk factors in light of the current literature. Methods: We performed a single-center, retrospective review of posterior spinal fusion patients with DJF who underwent subsequent revision surgery between June 2009 and January 2019. Demographics and surgical details were collected. Radiographical measurements included the following: preoperative and postoperative sagittal and coronal alignment for each index or revision surgery. The upper-instrumented vertebra (UIV), lower instrumented vertebra (LIV), and fusion length were recorded. Results: Nineteen cases (64.7 ± 13.5 years, 12 women, seven men) were included. The mean follow-up was 4.7 ± 2.4 years. The number of instrumented levels was 6.79 ± 2.97. Among the patients, 84.2% (n = 16) presented at least one known DJF risk factor. LIV was frequently L5 (n = 10) or S1 (n = 2). Six patients had an initial circumferential fusion at the distal end. Initial DJFs were vertebral fracture distal to the fusion (n = 5), screw pull-out (n = 9), spinal stenosis (n = 4), instability (n = 4), and one early DJK. The distal mechanical complications after a first revision included screw pull-out (n = 4), screw fracture (n = 3), non-union (n = 2), and an iatrogenic spondylolisthesis. Conclusions: In this case series, insufficient sagittal balance restoration, female gender, osteoporosis, L5 or S1 LIV in long constructs were associated with DJF. Restoring spinal balance and circumferentially fusing the base of constructs represent key steps to maintain correction and prevent revisions.

Bone Health Optimization in Adult Spinal Deformity Patients: A Narrative Review

Osteoporosis and low bone mineral density (BMD) pose significant challenges in adult spinal deformity surgery, increasing the risks of complications such as vertebral compression fractures, hardware failure, proximal junctional kyphosis/failure, and pseudoarthrosis. This narrative review examines the current evidence on bone health optimization strategies for spinal deformity patients. Preoperative screening and medical optimization are crucial, with vitamin D supplementation showing particular benefit. Among the pharmacologic agents, bisphosphonates demonstrate efficacy in improving fusion rates and reducing hardware-related complications, though the effects may be delayed. Teriparatide, a parathyroid hormone analog, shows promise in accelerating fusion and enhancing pedicle screw fixation. Newer anabolic agents like abaloparatide and romosozumab require further study but show potential. Romosozumab, in particular, has demonstrated significant improvements in lumbar spine BMD over a shorter duration compared to other treatments. Surgical techniques like cement augmentation and the use of larger interbody cages can mitigate the risks in osteoporotic patients. Overall, a multifaceted approach incorporating medical optimization, appropriate pharmacologic treatment, and tailored surgical techniques is recommended to improve outcomes in adult spinal deformity patients with compromised bone quality. Future research should focus on optimizing the treatment protocols, assessing the long-term outcomes of newer agents in the spine surgery population, and developing cost-effective strategies to improve access to these promising therapies.

Spinal cord injury in high-risk complex adult spinal deformity surgery: review of incidence and outcomes from the Scoli-RISK-1 study

STUDY DESIGN

Clinical case series.

OBJECTIVE

To describe the cause, treatment and outcome of 6 cases of perioperative spinal cord injury (SCI) in high-risk adult deformity surgery.

SETTING

Adult spinal deformity patients were enrolled in the multi-center Scoli-RISK-1 cohort study.

METHODS

A total of 272 patients who underwent complex adult deformity surgery were enrolled in the prospective, multi-center Scoli-RISK-1 cohort study. Clinical follow up data were available up to a maximum of 2 years after index surgery. Cases of perioperative SCI were identified and an extensive case review was performed.

RESULTS

Six individuals with SCI were identified from the Scoli-RISK-1 database (2.2%). Two cases occurred intraoperatively and four cases occurred postoperatively. The first case was an incomplete SCI due to a direct intraoperative insult and was treated postoperatively with Riluzole. The second SCI case was caused by a compression injury due to overcorrection of the deformity. Three cases of incomplete SCI occurred; one case of postoperative hematoma, one case of proximal junctional kyphosis (PJK) and one case of adjacent segment disc herniation. All cases of post-operative incomplete SCI were managed with revision decompression and resulted in excellent clinical recovery. One case of incomplete SCI resulted from infection and PJK. The patient's treatment was complicated by a delay in revision and the patient suffered persistent neurological deficits up to six weeks following the onset of SCI.

CONCLUSION

Despite the low incidence in high-risk adult deformity surgeries, perioperative SCI can result in devastating consequences. Thus, appropriate postoperative care, follow up and timely management of SCI are essential.

Impact of Hip and Knee Osteoarthritis on Full Body Sagittal Alignment and Compensation for Sagittal Spinal Deformity

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD).

BACKGROUND

Spine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD.

PATIENTS AND METHODS

In total, 527 preoperative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full-body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation.

RESULTS

The mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, and 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment ( P <0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt ( P =0.001) and sacrofemoral angle ( P <0.001), but increased knee flexion ( P =0.012). Regression analysis revealed that with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis ( r2 =0.812). Hip osteoarthritis decreased compensation through sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-coefficient=0.100).

CONCLUSIONS

For the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis.

Machine learning clustering of adult spinal deformity patients identifies four prognostic phenotypes: a multicenter prospective cohort analysis with single surgeon external validation

BACKGROUND CONTEXT

Among adult spinal deformity (ASD) patients, heterogeneity in patient pathology, surgical expectations, baseline impairments, and frailty complicates comparisons in clinical outcomes and research. This study aims to qualitatively segment ASD patients using machine learning-based clustering on a large, multicenter, prospectively gathered ASD cohort.

PURPOSE

To qualitatively segment adult spinal deformity patients using machine learning-based clustering on a large, multicenter, prospectively gathered cohort.

STUDY DESIGN/SETTING

Machine learning algorithm using patients from a prospective multicenter study and a validation cohort from a retrospective single center, single surgeon cohort with complete 2-year follow up.

PATIENT SAMPLE

About 805 ASD patients; 563 patients from a prospective multicenter study and 242 from a single center to be used as a validation cohort.

OUTCOME MEASURES

To validate and extend the Ames-ISSG/ESSG classification using machine learning-based clustering analysis on a large, complex, multicenter, prospectively gathered ASD cohort.

METHODS

We analyzed a training cohort of 563 ASD patients from a prospective multicenter study and a validation cohort of 242 ASD patients from a retrospective single center/surgeon cohort with complete two-year patient-reported outcomes (PROs) and clinical/radiographic follow-up. Using k-means clustering, a machine learning algorithm, we clustered patients based on baseline PROs, Edmonton frailty, age, surgical history, and overall health. Baseline differences in clusters identified using the training cohort were assessed using Chi-Squared and ANOVA with pairwise comparisons. To evaluate the classification system's ability to discern postoperative trajectories, a second machine learning algorithm assigned the single-center/surgeon patients to the same 4 clusters, and we compared the clusters' two-year PROs and clinical outcomes.

RESULTS

K-means clustering revealed four distinct phenotypes from the multicenter training cohort based on age, frailty, and mental health: Old/Frail/Content (OFC, 27.7%), Old/Frail/Distressed (OFD, 33.2%), Old/Resilient/Content (ORC, 27.2%), and Young/Resilient/Content (YRC, 11.9%). OFC and OFD clusters had the highest frailty scores (OFC: 3.76, OFD: 4.72) and a higher proportion of patients with prior thoracolumbar fusion (OFC: 47.4%, OFD: 49.2%). ORC and YRC clusters exhibited lower frailty scores and fewest patients with prior thoracolumbar procedures (ORC: 2.10, 36.6%; YRC: 0.84, 19.4%). OFC had 69.9% of patients with global sagittal deformity and the highest T1PA (29.0), while YRC had 70.2% exhibiting coronal deformity, the highest mean coronal Cobb Angle (54.0), and the lowest T1PA (11.9). OFD and ORC had similar alignment phenotypes with intermediate values for Coronal Cobb Angle (OFD: 33.7; ORC: 40.0) and T1PA (OFD: 24.9; ORC: 24.6) between OFC (worst sagittal alignment) and YRC (worst coronal alignment). In the single surgeon validation cohort, the OFC cluster experienced the greatest increase in SRS Function scores (1.34 points, 95%CI 1.01-1.67) compared to OFD (0.5 points, 95%CI 0.245-0.755), ORC (0.7 points, 95%CI 0.415-0.985), and YRC (0.24 points, 95%CI -0.024-0.504) clusters. OFD cluster patients improved the least over 2 years. Multivariable Cox regression analysis demonstrated that the OFD cohort had significantly worse reoperation outcomes compared to other clusters (HR: 3.303, 95%CI: 1.085-8.390).

CONCLUSION

Machine-learning clustering found four different ASD patient qualitative phenotypes, defined by their age, frailty, physical functioning, and mental health upon presentation, which primarily determines their ability to improve their PROs following surgery. This reaffirms that these qualitative measures must be assessed in addition to the radiographic variables when counseling ASD patients regarding their expected surgical outcomes.

Cost-Effectiveness of Corrective Fusion Surgeries for Adult Spinal Deformities: Does Unexpected Revision Surgery Affect Cost-Effectiveness?

Introduction

Previous research has demonstrated that mid- to long-term health-related quality of life following corrective fusion surgery for adult spinal deformity (ASD) can be improved by appropriate revision surgery. In this study, we aim to compare the cost-effectiveness of corrective fusion surgery for ASD with and without unexpected revision surgery 5 years postoperatively.

Methods

In total, 79 patients with ASD (mean age, 68.7 years) who underwent corrective fusion surgery between 2013 and 2015 were included in this study. Cost-effectiveness was evaluated based on the cost of obtaining 1 quality-adjusted life year (QALY). Patients were divided into two groups according to the presence or absence of unexpected revision surgery following corrective fusion and were subjected for comparison.

Results

As per our study findings, 26 (33%) of the 79 ASD patients underwent unexpected revision surgery during the first 5 years following surgery. Although there was no significant difference in terms of inpatient medical costs at the time of initial surgery for 5 years after surgery between the two groups (no-revision group, revision group; inpatient medical costs at the time of initial surgery: USD 69,854 vs. USD 72,685, P=0.344), the total medical expenses up to 5 years after surgery were found to be higher in the revision group (USD 72,704 vs. USD 104,287, P<0.001). The medical expenses required to improve 1 QALY 5 years after surgery were USD 178,476 in the no-revision group, whereas it was USD 222,081 in the revision group.

Conclusions

Although the total medical expenses were higher in the revision group, no significant difference was observed in the cumulative QALY improvement between the revision and no-revision groups. Moreover, the medical expenses required to improve 1 QALY were higher in the revision group, with a difference of approximately 20%.

Global Sagittal Angle and T9-tilt seem to be the most clinically and functionally relevant global alignment parameters in patients with Adult Spinal Deformity

Introduction

Radiographic analysis is necessary for the assessment and the surgical planning in adults with spinal deformity (ASD). Restoration of global alignment is key to improving patient's quality of life. However, the large number of existing global alignment parameters can be confusing for surgeons.

Research question

To determine the most clinically and functionally relevant global alignment parameters in ASD.

Material and methods

ASD and controls underwent full body biplanar X-ray to calculate global alignment parameters: odontoid to hip axis angle (OD-HA), global sagittal angle (GSA), global tilt (GT), SVA, center of auditory meatus to hip axis (CAM-HA), SSA, T1-tilt and T9-tilt. All subjects filled HRQoL questionnaires: ODI, SF-36, VAS for pain and BDI (Beck's Depression Inventory). 3D gait analysis was performed to calculate kinematic and spatio-temporal parameters. A machine learning model predicted gait parameters and HRQoL scores from global alignment parameters.

Results

124 primary ASD and 47 controls were enrolled. T9 tilt predicted the most BDI (31%), hip flexion/extension during gait (36%), and double support time (39%). GSA predicted the most ODI (26%), thorax flexion/extension during gait (33%), and cadence (36%).

Discussion and conclusion

Among all global alignment parameters, GSA, evaluating both trunk shift and knee flexion, and T9 tilt, evaluating the shift of the center of mass, were the best predictors for most of HRQoL scores and gait kinematics. Therefore, we recommend using GSA and T9 tilt in clinical practice when evaluating ASD because they represent the most quality of life and functional kinematic of these patients.

Practical Methods of Assessing Coronal Alignment and Outcomes in Adult Spinal Deformity Surgery: A Comparative Analysis

STUDY DESIGN

Asymptomatic cohort: prospective, cross-sectional, multicenter. Symptomatic: retrospective, multisurgeon, single-center.

OBJECTIVE

To assess the association between cranial coronal alignment and adult spinal deformity (ASD) surgical risk and outcomes.

SUMMARY OF BACKGROUND DATA

ASD leads to decreased quality of life. Studies have shown that coronal malignment (CM) is associated with worse surgical outcomes.

MATERIALS AND METHODS

A total of 468 adult participants were prospectively enrolled in the asymptomatic cohort. Totally, 172 symptomatic ASD patients with 2-year follow-ups were retrospectively enrolled in the symptomatic cohort. Three cranial plumb line parameters: the positions of the plumb lines from the midpoint between the medial orbital rims (ORB-L5), the odontoid (OD-L5), and the C7 centroid (C7-L5) relative to the L5 pedicle, were measured. Each subject had plumb line medial (M), touching (T), or lateral (L) to either pedicle. The association between each group of patients and radiographic parameters, intraoperative variables, patient-reported outcomes, and clinical outcomes were analyzed.

RESULTS

In the asymptomatic cohort, OD-L5 was medial to or touching the L5 pedicle in 98.3% of volunteers. In the symptomatic patients, preoperative OD-L5-L exhibited higher mean age (56.2±14.0), odontoid-coronal vertical axis (OD-CVA) (5.5±3.3 cm), Oswestry disability index (ODI) score (40.6±18.4), pelvic fixation rate (56/62, 90.3%), OR time (528.4±144.6 min), median estimated blood loss (1300 ml), and durotomy rate (24/62, 38.7%). A similar pattern of higher CVA, preoperative ODI, intraoperative pelvic fixation rate, OR time, estimated blood loss, and durotomy rate was observed in ORB-L5-L and C7-L5-L patients. Final follow-up postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis (13.0%) and pseudarthrosis (17.4%).

CONCLUSION

Preoperative OD-L5, ORB-L5, and C7-L5 lateral to pedicles were associated with worse preoperative ODI and higher intraoperative complexity. Postoperative OD-L5-L was associated with higher rates of proximal junctional kyphosis and pseudarthrosis. Postoperative CM, approximated by the cranial plumb line lateral to the L5 pedicles, was associated with sagittal plane complications.

Worse Preoperative Disability is Predictive of Improvement in Disability After Complex Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective Cohort Study.

OBJECTIVES

Few previous studies have examined the relationship between preoperative disability and patient outcomes after complex adult spinal deformity surgery. In this study, we hypothesized that patients with worse preoperative disability would be more likely achieve a clinically significant improvement in their symptoms after surgery.

METHODS

Demographics, comorbidities, surgical data, and health related survey results were analyzed from a consecutive series of adults (≥18 years old) who underwent spinal deformity correction, instrumentation, and fusion. Patients included had 6 or more levels fused and their surgery performed at single institution between 2015 and 2018 with minimum 2 year follow up.

RESULTS

A total of 108 patients met inclusion criteria. Bivariate analysis demonstrated the following as having a greater probability of reaching minimum clinically important difference (MCID) at 2 years postoperatively: >50th percentile Oswestry Disability Index (ODI) score (ODI >36), cardiac comorbidities, and use of pelvic fixation, pedicle subtraction osteotomy, and transforaminal lumbar interbody fusion. Conversely, baseline Scoliosis research society score (SRS) >50th percentile (SRS ≥62) and use of vertebral column resection (VCR) were significant predictors of not reaching MCID at 2 years. On logistic regression analysis, >50th percentile ODI score (ODI >36) was identified as the only independent predictor of achieving MCID.

CONCLUSIONS

Patients with greater disability, independent of other preoperative or surgical factors, are more likely to have clinically significant improvement in their daily functioning after complex deformity surgery. For patients who undergo surgical intervention for severe or progressive deformity, including VCR, MCID might be an ineffective outcome measure.

Adult spinal deformity correction surgery using age-adjusted alignment thresholds: clinical outcomes and mechanical complication rates. A systematic review of the literature

PURPOSE

Adult spinal deformity (ASD) surgery gives good clinical outcomes but has a high rate of mechanical complications (MC). In 2016, Lafage described the age-adjusted alignment thresholds (AAAT) to adapt the correction in relation to patient's age proposing less aggressive corrections for the elderly population. The aim of this review was to clarify the effectiveness of AAAT to achieve good health-related quality of life (HRQoL) and their relationship with post-operative MC.

MATERIALS AND METHODS

We performed a review of the literature, including articles reporting data on post-operative HRQoL and MC rates in relation to the AAAT. Data were stratified according to whether they matched the AAAT, dividing the population in undercorrected (U), matched (M) and overcorrected (O). The quality of the included studies was assessed using the GRADE and MINORS systems.

RESULTS

Six articles reporting data from 1,825 patients were included. The different categories (U, M and O) had homogeneous pre-operative sagittal parameters (p > 0.05) that became statistically different after surgeries (p < 0.05). Proximal junctional kyphosis (PJK) was more frequent in the O group compared to U (p = 0.05). Post-operative HRQoL parameters were similar in the 3 groups (p > 0.05). The quality of the included studies was generally low with a high bias risk.

CONCLUSION

The results extrapolated from this review are interesting, as for the same HRQoL the U group had a lower MC rate. Unfortunately, the results are inconsistent, mainly because of the low quality of the included studies and the lack of reporting of some important patient- and surgery-related factors.

Percutaneous Juxtapedicular Cement Salvage of Failed Spinal Instrumentation? Institutional Experience and Cadaveric Biomechanical Study

BACKGROUND AND OBJECTIVES

Instrumented spinal fusion constructs sometimes fail because of fatigue loading, frequently necessitating open revision surgery. Favorable outcomes after percutaneous juxtapedicular cement salvage (perc-cement salvage) of failing instrumentation have been described; however, this approach is not widely known among spine surgeons , and its biomechanical properties have not been evaluated. We report our institutional experience with perc-cement salvage and investigate the relative biomechanical strength of this technique as compared with 3 other common open revision techniques.

METHODS

A retrospective chart review of patients who underwent perc-cement salvage was conducted. Biomechanical characterization of revision techniques was performed in a cadaveric model of critical pedicle screw failure. Three revision cohorts involved removal and replacement of hardware: (1) screw upsizing, (2) vertebroplasty, and (3) fenestrated screw with cement augmentation. These were compared with a cohort with perc-cement salvage performed using a juxtapedicular trajectory with the failed primary screw remaining engaged in the vertebral body.

RESULTS

Ten patients underwent perc-cement salvage from 2018 to 2022 to address screw haloing and/or endplate fracture threatening construct integrity. Pain palliation was reported by 8/10 patients. Open revision surgery was required in 4/10 patients, an average of 8.9 months after the salvage procedure (range 6.2-14.7 months). Only one revision was due to progressive hardware dislodgement. The remainder avoided open revision surgery through an average of 1.9 years of follow-up. In the cadaveric study, there were no significant differences in pedicle screw pullout strength among any of the revision cohorts.

CONCLUSION

Perc-cement salvage of failing instrumentation is reasonably efficacious. The technique is biomechanically noninferior to other revision strategies that require open surgery for removal and replacement of hardware. Open revision surgery may be avoided by perc-cement salvage in select cases.

Adult cervical spine deformity: a state-of-the-art review

Adult cervical deformity is a structural malalignment of the cervical spine that may present with variety of significant symptomatology for patients. There are clear and substantial negative impacts of cervical spine deformity, including the increased burden of pain, limited mobility and functionality, and interference with patients' ability to work and perform everyday tasks. Primary cervical deformities develop as the result of a multitude of different etiologies, changing the normal mechanics and structure of the cervical region. In particular, degeneration of the cervical spine, inflammatory arthritides and neuromuscular changes are significant players in the development of disease. Additionally, cervical deformities, sometimes iatrogenically, may present secondary to malalignment or correction of the thoracic, lumbar or sacropelvic spine. Previously, classification systems were developed to help quantify disease burden and influence management of thoracic and lumbar spine deformities. Following up on these works and based on the relationship between the cervical and distal spine, Ames-ISSG developed a framework for a standardized tool for characterizing and quantifying cervical spine deformities. When surgical intervention is required to correct a cervical deformity, there are advantages and disadvantages to both anterior and posterior approaches. A stepwise approach may minimize the drawbacks of either an anterior or posterior approach alone, and patients should have a surgical plan tailored specifically to their cervical deformity based upon symptomatic and radiographic indications. This state-of-the-art review is based upon a comprehensive overview of literature seeking to highlight the normal cervical spine, etiologies of cervical deformity, current classification systems, and key surgical techniques.

Lateral access minimally invasive spine surgery in adult spinal deformity

Background

Oblique lumbar interbody fusion (OLIF) and percutaneous posterior approach for screw fixation (PPS) is the latest minimal invasive treatment for spinal deformity in adult patients (ASD). This study aims to design and highlight key points for ASD correction.

Materials and methods

We retrospectively analyzed 54 patients who had undergone OLIF with PPS for ASD from October 2019 to January 2022 (average 71.5 ± 6.2 years-old, male 4, female 50) with a mean follow-up period of 29.2 months. Clinical outcomes are expressed by values including the Oswestry disability index (ODI) and visual analogue scale (VAS) for back pain. The imagistic assessment was also performed preoperatively and at 12, and 24 months postoperatively. For OLIF51, CT- MRI fusion images were obtained before surgery.

Results

Postoperative ODI and VAS were 30.5 ± 18.9% and 31.2 ± 6.9 mm, respectively. The average operating time and blood loss during the surgical exposure was 490.9 ± 85.4 min and 1195.2 ± 653.8 ml. Preoperative SVA, PI-LL, and PT were 96.5 ± 55.9 mm, 39.3 ± 22.1°, 34.5 ± 11.0°, respectively. Postoperatively, SVA and PT became normal (24.1 ± 39.0 mm, 17.1 ± 10.3°) and PI-LL was ideal (2.4 ± 12.6°). Postoperative ODI and VAS were 30.5 ± 18.9% and 31.2 ± 6.9 mm. For OLIF51, the results revealed gain in L5-S1 lordosis and intervertebral disc height 9.4° and 4.2 mm respectively. The complications consisted of PJK in 21 cases (38.9%), rod breakage in 5 cases (9.3%), deep or superficial wound infection in 2 cases (3.7%).

Conclusion

Clinical and imagistic results of OLIF and PPS for ASD were excellent. The radiographic measurements revealed that OLIF51 created good L5-S1 lordosis and significant L5-S1 disc height. CT-MRI fusion images were very useful for evaluating vascular anatomy for OLIF51.

Morphological description of sagittal lumbar spinal alignment using curve magnitude, span, and apex-the multiethnic alignment normative study (MEANS)

BACKGROUND CONTEXT

Current definition of lumbar lordosis uses the L1-S1 angle. Prevailing classification of sagittal spinal morphology, derived from a young adult population, classifies the spine into four subtypes defined by their sacral slope (SS) and curve morphology.

PURPOSE

To describe physiological sagittal alignment of the lumbar spine across age groups using three main parameters that dictate the lumbar curve: angular magnitude, span, and apex.

STUDY DESIGN

A large, multicenter, cross-sectional radiographic comparison study.

PATIENT SAMPLE

Four hundred sixty-eight healthy, asymptomatic subjects aged 18 to 80 years from five countries (184 males, 284 females; 98 France, 119 Japan, 79 Singapore, 80 Tunisia, 92 USA, mean age 40.61±14.99 years).

OUTCOME MEASURES

Sagittal lumbar profile subtypes clustered based on lumbar curve angular magnitude (ie, Cobb angle of the lumbar lordosis), span, and apex, and described by sagittal radiographic parameters.

METHODS

Subjects underwent whole-body low-dose EOS stereoradiographs. Comparisons between conventional L1-S1 lumbar lordosis (cLL) and true lumbar lordosis (tLL, defined by the inflection-S1 angle) were conducted. Using the K-means clustering algorithm, lumbar curve angular magnitude, span and apex were used to classify sagittal spinal morphology into subtypes, stratified across age groups. Further univariate and multivariate analyses were conducted to compare radiographic parameters across subtypes, and identify predictors for the lumbar curve's angular magnitude, span and apex.

RESULTS

Mean cLL was -57.27±11.37°, and tLL was -62.62±10.76°. Using tLL, instead of cLL, to describe sagittal spinal morphology, we found significant differences in terms of angular magnitude of the lumbar curve, the median thoracolumbar inflection vertebral level and pelvic incidence-lumbar lordosis mismatch Multivariate analysis found a larger SS, more positive T9 tilt, and more kyphotic T4-T12 predictive for a more lordotic tLL, while a larger overhang distance predicted for a less lordotic tLL (p-values<.001). In addition, a larger T9 tilt, less lordotic L1-L5 and smaller PT were predictors of a more caudal thoracolumbar inflection and lumbar apical vertebral levels (p-values<.001). Sagittal lumbar profiles of subjects age<30 years, 30≤age<60 years and age≥60 years, could be classified into 4, 6, and 3 subtypes, respectively.

CONCLUSIONS

Sagittal lumbar profile subtypes vary across age groups, with more homogenous morphologies at the extremes of ages. Improved understanding of the morphological evolution of sagittal spinal profiles with age in asymptomatic individuals will help guide future individualized surgical treatment.

Proximal Junctional Kyphosis and Failure: Strategies for Prevention

Proximal junctional kyphosis (PJK) and proximal junctional failure/fractures (PJF) are common complications following long-segment posterior instrumented fusions for adult spinal deformity. As progression to PJF involves clinical consequences for patients and requires costly revisions that may undermine the utility of surgery and are ultimately unsustainable for health care systems, preventative strategies to minimize the occurrence of PJF are of tremendous importance. In this article, the authors present a detailed outline of PJK and PJF with a focus on surgical strategies aimed at preventing their occurrence..

Multiple-Rod Constructs in Adult Spinal Deformity Surgery: A Systematic Review and Meta-Analysis

The purpose of this research was to compare the therapeutic efficacy of multiple-rod constructs vis-a-vis 2-rod constructs in the treatment of adult spinal deformity. A systematic review and meta-analysis were performed to determine whether the multiple-rod construct outperformed the 2-rod construct. We initially retrieved 357 papers, but only 12 were chosen for further meta-analysis. The rod breakage rates in the multiple-rod and the 2-rod groups were 10.66% and 29.87%, respectively. The multiple-rod construct inhibited rod breakage (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.19-0.41; p<0.001), pseudarthrosis (OR, 0.30; 95% CI, 0.18-0.50; p<0.001) and rod fracture at the osteotomy site (OR, 0.34; 95% CI, 0.13-0.89; p=0.03). Furthermore, the multiple-rod construct reduces the risk of revision surgery (OR, 0.38; 95% CI, 0.20-0.73; p=0.04) as well as the revision risk of pseudarthrosis/rod fracture in the multiple- rod group (OR, 0.31; 95% CI, 0.18-0.52; p<0.001), but increases the risk of caudal screw loosening (OR, 4.99; 95% CI, 1.87-13.30; p=0.001). There was no statistically significant difference in proximal junctional kyphosis (PJK) parameters (p=0.85), cerebrospinal fluid leakage (p=0.09), wound infection (p =0.71), age at surgery (p=0.62), gender distribution (p=0.93), body mass index (p =0.86), smoking status (p=0.05), hospital stay (p=0.09), osteoporosis (p=0.95), CoCr rod material (p=0.15), bone morphogenetic protein-2 (p=0.58), L5/S1 interbody fusion (p=0.07), high-grade osteotomies (p=0.07), the number of fusion levels (p=0.11), operation time (p=0.30), and blood loss volume (p=0.34). Regarding radiographic parameters, only preoperative sagittal vertical axis was found to be higher (weight means difference [WMD], 25.60; 95% CI, 15.43-35.77; p<0.001) in the multiple-rod group. There was no difference in preoperative Oswestry Disability Index (ODI) (WMD, -3.32; 95% CI, -7.38 to 0.73; p=0.11), but the multiple-rod group had a lower ODI at follow-up (WMD, -7.71; 95% CI, -11.62 to -3.86; p<0.001). Multiple-rod constructs could prevent rod breakage and pseudarthrosis while also lowering the revision rate, resulting in a better clinical outcome than the 2-rod construct. Nonetheless, due consideration should be given to PJK and screw loosening in multiple-rod constructs, possibly due to the increased stiffness caused by the multiple-rod structure.

Robotic-Assisted Surgery and Navigation in Deformity Surgery

Deformity surgery is advancing quickly with the use of three-dimensional navigation and robotics. In spinal fusion, the use of robotics improves screw placement accuracy and reduces radiation, complications, blood loss, and recovery time. Currently, there is limited evidence showing that robotics is better than traditional freehand techniques. Most studies favoring robotics are small and retrospective due to the novelty of the technology in deformity surgery. Using these systems can also be expensive and time-consuming. Surgeons should use these advancements as tools, but not rely on them to replace surgical experience, anatomy knowledge, and good judgment.

Algorithmic Patient Selection for Minimally Invasive Versus Open Lumbar Interbody Fusion Surgery

Evidenced-based data-driven decision-making algorithms guide patient and approach selection for adult spinal deformity surgery. Algorithms are continually refined as surgical goals and intraoperative technology evolve.

Comparison of complications, revisions, spinopelvic parameters, and health-related quality of life after posterior spinal fusion using multiple-rod constructs or two-rod constructs for adult spinal deformity: a systematic review and meta-analysis

BACKGROUND

The incidence of mechanical complications is high in patients undergoing posterior spinal fusion (PSF) for adult spinal deformity (ASD), especially for cases with severe sagittal malalignment or a prior spinal fusion requiring three-column osteotomy (3-CO) or spinopelvic fixation (SPF). The purpose of this systematic review and meta-analysis was to compare the complications, revisions, radiographic spinopelvic parameters, health-related quality of life (HRQoL), and surgical data of PSF using multiple-rod constructs to those of two-rod constructs for the treatment of ASD.

METHODS

A comprehensive literature search was performed for relevant studies in PubMed, EMBASE, Web of Science, and the Cochrane Library. Complications, revisions, spinopelvic parameters, HRQoL, and surgical date were compared between patients with ASD who underwent PSF using multiple-rod constructs (multi-rod group) and two-rod constructs (two-rod group).

RESULTS

Ten studies, comprising 797 patients with ASD (399 in the multi-rod group and 398 in the two-rod group), were included. All these studies were retrospective cohort studies. There were no significant differences in the surgical, wound-related, and systemic complications between the groups. In the multi-rod group, we noted a significantly lower incidence of rod fracture (RR, 0.43; 95% CI 0.33 to 0.57, P < 0.01), pseudoarthrosis (RR, 0.38; 95% CI 0.28 to 0.53, P < 0.01), and revisions (RR, 0.44; 95% CI 0.33 to 0.58, P < 0.01); a superior restoration of PI-LL (WMD, 3.96; 95% CI 1.03 to 6.88, P < 0.01) and SVA (WMD, 31.53; 95% CI 21.16 to 41.90, P < 0.01); a better improvement of ODI score (WMD, 6.82; 95% CI 2.33 to 11.31, P < 0.01), SRS-22 total score (WMD, 0.44; 95% CI 0.06 to 0.83, P = 0.02), and VAS-BP score (WMD, 1.02; 95% CI 0.31 to 1.73, P < 0.01).

CONCLUSION

Compared with the two-rod constructs, PSF using multiple-rod constructs was associated with a lower incidence of mechanical complications, a lower revision rate, a superior restoration of sagittal alignment, and a better improvement of HRQoL, without increasing surgical invasiveness. Multiple-rod constructs should be routinely considered to for ASD patients, especially for cases with severe sagittal malalignment or a prior spinal fusion requiring 3-CO or SPF.

Height Gain Following Correction of Adult Spinal Deformity

BACKGROUND

Height gain following a surgical procedure for patients with adult spinal deformity (ASD) is incompletely understood, and it is unknown if height gain correlates with patient-reported outcome measures (PROMs).

METHODS

This was a retrospective cohort study of patients undergoing ASD surgery. Patients with baseline, 6-week, and subanalysis of 1-year postoperative full-body radiographic and PROM data were examined. Correlation analysis examined relationships between vertical height differences and PROMs. Regression analysis was utilized to preoperatively estimate T1-S1 and S1-ankle height changes.

RESULTS

This study included 198 patients (mean age, 57 years; 69% female); 147 patients (74%) gained height. Patients with height loss, compared with those who gained height, experienced greater increases in thoracolumbar kyphosis (2.81° compared with -7.37°; p < 0.001) and thoracic kyphosis (12.96° compared with 4.42°; p = 0.003). For patients with height gain, sagittal and coronal alignment improved from baseline to postoperatively: 25° to 21° for pelvic tilt (PT), 14° to 3° for pelvic incidence - lumbar lordosis (PI-LL), and 60 mm to 17 mm for sagittal vertical axis (SVA) (all p < 0.001). The full-body mean height gain was 7.6 cm, distributed as follows: sella turcica-C2, 2.9 mm; C2-T1, 2.8 mm; T1-S1 (trunk gain), 3.8 cm; and S1-ankle (lower-extremity gain), 3.3 cm (p < 0.001). T1-S1 height gain correlated with the thoracic Cobb angle correction and the maximum Cobb angle correction (p = 0.002). S1-ankle height gain correlated with the corrections in PT, PI-LL, and SVA (p < 0.001). T1-ankle height gain correlated with the corrections in PT (p < 0.001) and SVA (p = 0.03). Trunk height gain correlated with improved Scoliosis Research Society (SRS-22r) Appearance scores (r = 0.20; p = 0.02). Patient-Reported Outcomes Measurement Information System (PROMIS) Depression scores correlated with S1-ankle height gain (r = -0.19; p = 0.03) and C2-T1 height gain (r = -0.18; p = 0.04). A 1° correction in a thoracic scoliosis Cobb angle corresponded to a 0.2-mm height gain, and a 1° correction in a thoracolumbar scoliosis Cobb angle resulted in a 0.25-mm height gain. A 1° improvement in PI-LL resulted in a 0.2-mm height gain.

CONCLUSIONS

Most patients undergoing ASD surgery experienced height gain following deformity correction, with a mean full-body height gain of 7.6 cm. Height gain can be estimated preoperatively with predictive ratios, and height gain was correlated with improvements in reported SRS-22r appearance and PROMIS scores.

LEVEL OF EVIDENCE

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

Outcomes of Surgical Treatment for Patients With Mild Scoliosis and Age-Appropriate Sagittal Alignment With Minimum 2-Year Follow-up

OBJECTIVE

The goal of this study was to determine if patients with mild scoliosis and age-appropriate sagittal alignment have favorable outcomes following surgical correction.

METHODS

Retrospective review of a prospective, multicenter adult spinal deformity database. Inclusion criteria: operative patients age ≥18 years, and preoperative pelvic tilt, mismatch between pelvic incidence and lumbar lordosis (PI-LL), and C7 sagittal vertical axis all within established age-adjusted thresholds with minimum 2-year follow-up. Health-related quality of life (HRQoL) scores: Oswestry Disability Index (ODI), 36-item Short Form health survey (SF-36), Scoliosis Research Society-22R (SRS22R), back/leg pain Numerical Rating Scale and minimum clinically important difference (MCID)/substantial clinical benefit (SCB). Two-year and preoperative HRQoL radiographic data were compared. Patients with mild scoliosis (Mild Scoli, Max coronal Cobb 10°-30°) were compared to those with larger curves (Scoli).

RESULTS

One hundred fifty-one patients included from 667 operative patients (82.8% women; average age, 56.4 ± 16.2 years). Forty-two patients (27.8%) included in Mild Scoli group. Mild Scoli group had significantly worse baseline leg pain, ODI, and physical composite scores (p < 0.02). Mean 2-year maximum coronal Cobb angle was significantly improved compared to baseline (p < 0.001). All 2-year HRQoL measures were significantly improved compared to (p < 0.001) except mental composite score, SRS activity and SRS mental for the Mild Scoli group (p > 0.05). From the mild Scoli group, 36%-74% met either MCID or SCB for the HRQoL measures. Sixty-four point three percent had minimum 1 complication, 28.6% had a major complication, 35.7% had reoperation.

CONCLUSION

Mild scoliosis patients with age-appropriate sagittal alignment benefit from surgical correction, decompression, and stabilization at 2 years postoperative despite having a high complication rate.

Are We Focused on the Wrong Early Postoperative Quality Metrics? Optimal Realignment Outweighs Perioperative Risk in Adult Spinal Deformity Surgery

BACKGROUND

While reimbursement is centered on 90-day outcomes, many patients may still achieve optimal, long-term outcomes following adult spinal deformity (ASD) surgery despite transient short-term complications.

OBJECTIVE

Compare long-term clinical success and cost-utility between patients achieving optimal realignment and suboptimally aligned peers.

STUDY DESIGN/SETTING

Retrospective cohort study of a prospectively collected multicenter database.

METHODS

ASD patients with two-year (2Y) data included. Groups were propensity score matched (PSM) for age, frailty, body mass index (BMI), Charlson Comorbidity Index (CCI), and baseline deformity. Optimal radiographic criteria are defined as meeting low deformity in all three (Scoliosis Research Society) SRS-Schwab parameters or being proportioned in Global Alignment and Proportionality (GAP). Cost-per-QALY was calculated for each time point. Multivariable logistic regression analysis and ANCOVA (analysis of covariance) adjusting for baseline disability and deformity (pelvic incidence (PI), pelvic incidence minus lumbar lordosis (PI-LL)) were used to determine the significance of surgical details, complications, clinical outcomes, and cost-utility.

RESULTS

A total of 930 patients were considered. Following PSM, 253 "optimal" (O) and 253 "not optimal" (NO) patients were assessed. The O group underwent more invasive procedures and had more levels fused. Analysis of complications by two years showed that the O group suffered less overall major (38% vs. 52%, p = 0.021) and major mechanical complications (12% vs. 22%, p = 0.002), and less reoperations (23% vs. 33%, p = 0.008). Adjusted analysis revealed O patients more often met MCID (minimal clinically important difference) in SF-36 PCS, SRS-22 Pain, and Appearance. Cost-utility-adjusted analysis determined that the O group generated better cost-utility by one year and maintained lower overall cost and costs per QALY (both p < 0.001) at two years.

CONCLUSIONS

Fewer late complications (mechanical and reoperations) are seen in optimally aligned patients, leading to better long-term cost-utility overall. Therefore, the current focus on avoiding short-term complications may be counterproductive, as achieving optimal surgical correction is critical for long-term success.

The Thoracolumbar Inflection Point in a Population of Asymptomatic Volunteers: A Multi-Ethnic Alignment Normative Study Cohort Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To show population variance in the Inflection Point (IP) and its role in defining maximum Thoracic Kyphosis (TK) and Lumbar Lordosis (LL).

METHODS

468 asymptomatic adult volunteers were included in the Multi-Ethnic Normative Alignment Study (MEANS). To find parameters correlating with IP, the vertebrae and discs were numbered such that C7 was 0, T1 was 1, with T1-T2 disc being 1.5, etc. Statistical analysis was performed by a correlation matrix for IP and the 9 other selected parameters along with linear regressions.

RESULTS

The overall mean IP was 12.44 approximately corresponding to T12-L1 disc with the median being 12.50, range was T8-L4. The cohort was then stratified by sex and ethnicity, but there was no significant difference in IP between groups. IP in younger subjects was 13 (L1), compared to 12.5 (T12-L1 disc) in older subjects (P < .05). IP was moderately correlated with the TK apex (r = .66). No strong correlation was found between IP and LL magnitude or apex, TK magnitude, sacral slope, or Pelvic Incidence (PI). In terms of other sagittal parameters, PI and LL demonstrated a significant positive correlation. PI and TK did not have a strong association.

CONCLUSIONS

The mean IP was at the T12-L1 disc, however IP ranged from T8 to L4. Older subjects tended to have a relatively more cephalad IP. No radiographic variable was found to be a strong predictor of the IP. TK apex was found to have a moderate correlation.

Lateral interbody fusion without intraoperative neuromonitoring in addition to posterior instrumented fusion in geriatric patients: A single center consecutive series of 108 surgeries

Introduction

Lateral lumbar interbody fusion (LLIF) and lateral thoracic interbody fusion (LTIF), supported by intraoperative neuromonitoring (IONM), gained popularity as a mini-invasive alternatives for standard interbody fusion. The objective of this study was to investigate the clinical outcome in a large elderly patient cohort who underwent LTIF/LLIF without IONM.

Methods

This retrospective, single-center study enrolled elderly patients (≥70 years old) operated during the period from 2010 to 2016. Anterior lumbar interbody fusion (ALIF) in the L5/S1 segment was excluded from the analysis.

Results

The study enrolled 108 patients (63 males, 58.3%) with a mean age of 76.5 ​y/o. The mean follow-up was 14.4 ​± ​11.3 months. The mean time of the surgery was 92 ​± ​34.2 ​min. The mean blood loss was 62.2 ​ml. There were no vascular or visceral surgical complications. 39 medical complications were encountered in 24 (22%) patients. Less than 5% of patients presented with a new onset of motor weakness and less than 2% of the patients developed a new sensory deficit at the discharge. 46% of patients were lost in follow-up at 12 months.

Conclusions

IONM is not mandatory for LLIF/LTIF surgery in geriatric patients and has a low frequency of approach-related complications as well as neurological deterioration. Our results are comparable to the available literature. Regardless of the utilization of these mini-invasive, anterior approaches, in patients of advanced aged, the risk for major medical complications is high and is responsible for contributing to prolonged hospitalization.

Preoperative medical assessment for adult spinal deformity surgery: a state-of-the-art review

INTRODUCTION

The purpose of this study is to provide a state-of-the-art review regarding risk factors for perioperative complications in adult spinal deformity (ASD) surgery. The review includes levels of evidence for risk factors associated with complications in ASD surgery.

METHODS

Using the PubMed database, we searched for complications, risk factors, and adult spinal deformity. The included publications were assessed for level of evidence as described in clinical practice guidelines published by the North American Spine Society, with summary statements generated for each risk factor (Bono et al. in Spine J 9:1046-1051, 2009).

RESULTS

Frailty had good evidence (Grade A) as a risk for complications in ASD patients. Fair evidence (Grade B) was assigned for bone quality, smoking, hyperglycemia and diabetes, nutritional status, immunosuppression/steroid use, cardiovascular disease, pulmonary disease, and renal disease. Indeterminate evidence (Grade I) was assigned for pre-operative cognitive function, mental health, social support, and opioid utilization.

CONCLUSIONS

Identification of risk factors for perioperative complications in ASD surgery is a priority for empowering informed choices for patients and surgeons and managing patient expectations. Risk factors with grade A and B evidence should be identified prior to elective surgery and modified to reduce the risk of perioperative complications.

Creation and Evaluation of a Severity Classification of Hyperkyphosis and Hypolordosis for Exercise Therapy

The rise in the occurrence of musculoskeletal disorders, such as thoracic hyperkyphosis (THK) or lumbar hypolordosis (LHL), is a result of demographic changes. Exercise therapy is an effective approach that can reduce related disabilities and costs. To ensure successful therapy, an individualized exercise program adapted to the severity of the disorder is expedient. Nevertheless, appropriate classification systems are scarce. This project aimed to develop and evaluate a severity classification focused on exercise therapy for patients with THK or LHL. A multilevel severity classification was developed and evaluated by means of an online survey. Reference limits of spinal shape angles were established by data from video rasterstereography of 201 healthy participants. A mean kyphosis angle of 50.03° and an average lordosis angle of 40.72° were calculated as healthy references. The strength of the multilevel classification consisting of the combination of subjective pain and objective spinal shape factors was confirmed by the survey (70% agreement). In particular, the included pain parameters were considered relevant by 78% of the experts. Even though the results of the survey provide important evidence for further analyses and optimization options of the classification system, the current version is still acceptable as therapeutic support.

Comparison of C-Arm-Free Oblique Lumbar Interbody Fusion L5-S1 (OLIF51) with Transforaminal Lumbar Interbody Fusion L5-S1 (TLIF51) for Adult Spinal Deformity

Background and Objectives: Adult spinal deformity (ASD) surgery, L5-S1 lordosis is very important factor. The main objective of the research is to retrospectively compare symptomatic presentation and radiological presentation in the sequelae of oblique lumbar inter-body spinal fusion at L5-S1 (OLIF51) and transforaminal lumbar interbody fusion (TLIF) for ASD. Materials and Methods: We retrospectively evaluated 54 patients who underwent corrective spinal fusion for ASD between October 2019 and January 2021. Thirteen patients underwent OLIF51 (average 74.6 years old, group O) and 41 patients underwent TLIF51 (average 70.5 years old, group T). Mean follow-up period was 23.9 months for group O and 28.9 months for group T, ranging from 12 to 43 months. Clinical and radiographic outcomes are assessed using values including visual analogue scale (VAS) for back pain and Oswestry disability index (ODI). Radiographic evaluation was also collected preoperatively and at 6, 12, and 24 months postoperatively. Results: Surgical time in group O was less than that in group T (356 min vs. 492 min, p = 0.003). However, intraoperative blood loss of both groups were not significantly different (1016 mL vs. 1252 mL, p = 0.274). Changes in VAS and ODI were similar in both groups. L5-S1 angle gain and L5-S1 height gain in group O were significantly better than those of group T (9.4° vs. 1.6°, p = 0.0001, 4.2 mm vs. 0.8 mm, p = 0.0002). Conclusions: Clinical outcomes were not significantly different in both groups, but surgical time in OLIF51 was significantly less than that in TLIF51. The radiographic outcomes showed that OLIF51 created more L5-S1 lordosis and L5-S1 disc height compared with TLIF 51.

Biomechanical evaluation of multiple pelvic screws and multirod construct for the augmentation of lumbosacral junction in long spinal fusion surgery

Background: Posterior long spinal fusion was the common procedure for adult spinal deformity (ASD). Although the application of sacropelvic fixation (SPF), the incidence of pseudoarthrosis and implant failure is still high in long spinal fusion extending to lumbosacral junction (LSJ). To address these mechanical complications, advanced SPF technique by multiple pelvic screws or multirod construct has been recommended. This was the first study to compare the biomechanical performance of combining multiple pelvic screws and multirod construct to other advanced SPF constructs for the augmentation of LSJ in long spinal fusion surgery through finite element (FE) analysis.

Methods: An intact lumbopelvic FE model based on computed tomography images of a healthy adult male volunteer was constructed and validated. The intact model was modified to develop five instrumented models, all of which had bilateral pedicle screw (PS) fixation from L1 to S1 with posterior lumbar interbody fusion and different SPF constructs, including No-SPF, bilateral single S2-alar-iliac (S2AI) screw and single rod (SS-SR), bilateral multiple S2AI screws and single rod (MS-SR), bilateral single S2AI screw and multiple rods (SS-MR), and bilateral multiple S2AI screws and multiple rods (MS-MR). The range of motion (ROM) and stress on instrumentation, cages, sacrum, and S1 superior endplate (SEP) in flexion (FL), extension (EX), lateral bending (LB), and axial rotation (AR) were compared among models.

Results: Compared with intact model and No-SPF, the ROM of global lumbopelvis, LSJ, and sacroiliac joint (SIJ) was decreased in SS-SR, MS-SR, SS-MR, and MS-MR in all directions. Compared with SS-SR, the ROM of global lumbopelvis and LSJ of MS-SR, SS-MR, and MS-MR further decreased, while the ROM of SIJ was only decreased in MS-SR and MS-MR. The stress on instrumentation, cages, S1-SEP, and sacrum decreased in SS-SR, compared with no-SPF. Compared with SS-SR, the stress in EX and AR further decreased in SS-MR and MS-SR. The most significantly decreased ROM and stress were observed in MS-MR.

Conclusion: Both multiple pelvic screws and multirod construct could increase the mechanical stability of LSJ and reduce stress on instrumentation, cages, S1-SEP, and sacrum. The MS-MR construct was the most adequate to reduce the risk of lumbosacral pseudarthrosis, implant failure, and sacrum fracture. This study may provide surgeons with important evidence for the application of MS-MR construct in the clinical settings.

Predictive models to assess risk of extended length of stay in adults with spinal deformity and lumbar degenerative pathology: development and internal validation

BACKGROUND CONTEXT

Postoperative recovery after adult spinal deformity (ASD) operations is arduous, fraught with complications, and often requires extended hospital stays. A need exists for a method to rapidly predict patients at risk for extended length of stay (eLOS) in the preoperative setting.

PURPOSE

To develop a machine learning model to preoperatively estimate the likelihood of eLOS following elective multi-level lumbar/thoracolumbar spinal instrumented fusions (≥3 segments) for ASD.

STUDY DESIGN/SETTING

Retrospectively from a state-level inpatient database hosted by the Health care cost and Utilization Project.

PATIENT SAMPLE

Of 8,866 patients of age ≥50 with ASD undergoing elective lumbar or thoracolumbar multilevel instrumented fusions.

OUTCOME MEASURES

The primary outcome was eLOS (>7 days).

METHODS

Predictive variables consisted of demographics, comorbidities, and operative information. Significant variables from univariate and multivariate analyses were used to develop a logistic regression-based predictive model that use six predictors. Model accuracy was assessed through area under the curve (AUC), sensitivity, and specificity.

RESULTS

Of 8,866 patients met inclusion criteria. A saturated logistic model with all significant variables from multivariate analysis was developed (AUC=0.77), followed by generation of a simplified logistic model through stepwise logistic regression (AUC=0.76). Peak AUC was reached with inclusion of six selected predictors (combined anterior and posterior approach, surgery to both lumbar and thoracic regions, ≥8 level fusion, malnutrition, congestive heart failure, and academic institution). A cutoff of 0.18 for eLOS yielded a sensitivity of 77% and specificity of 68%.

CONCLUSIONS

This predictive model can facilitate identification of adults at risk for eLOS following elective multilevel lumbar/thoracolumbar spinal instrumented fusions for ASD. With a fair diagnostic accuracy, the predictive calculator will ideally enable clinicians to improve preoperative planning, guide patient expectations, enable optimization of modifiable risk factors, facilitate appropriate discharge planning, stratify financial risk, and accurately identify patients who may represent high-cost outliers. Future prospective studies that validate this risk assessment tool on external datasets would be valuable.

Rod fractures in thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective, multicenter cohort of 160 patients

OBJECTIVE

Previous reports of rod fracture (RF) in adult spinal deformity are limited by heterogeneous cohorts, low follow-up rates, and relatively short follow-up durations. Since the majority of RFs present > 2 years after surgery, true occurrence and revision rates remain unclear. The objectives of this study were to better understand the risk factors for RF and assess its occurrence and revision rates following primary thoracolumbar fusions to the sacrum/pelvis for adult symptomatic lumbar scoliosis (ASLS) in a prospective series with long-term follow-up.

METHODS

Patient records were obtained from the Adult Symptomatic Lumbar Scoliosis-1 (ASLS-1) database, an NIH-sponsored multicenter, prospective study. Inclusion criteria were as follows: patients aged 40-80 years undergoing primary surgeries for ASLS (Cobb angle ≥ 30° and Oswestry Disability Index ≥ 20 or Scoliosis Research Society-22r ≤ 4.0 in pain, function, and/or self-image) with instrumented fusion of ≥ 7 levels that included the sacrum/pelvis. Patients with and without RF were compared to assess risk factors for RF and revision surgery.

RESULTS

Inclusion criteria were met by 160 patients (median age 62 years, IQR 55.7-67.9 years). At a median follow-up of 5.1 years (IQR 3.8-6.6 years), there were 92 RFs in 62 patients (38.8%). The median time to RF was 3.0 years (IQR 1.9-4.54 years), and 73% occurred > 2 years following surgery. Based on Kaplan-Meier analyses, estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Baseline radiographic, clinical, and demographic characteristics were similar between patients with and without RF. In Cox regression models, greater postoperative pelvic tilt (HR 1.895, 95% CI 1.196-3.002, p = 0.0065) and greater estimated blood loss (HR 1.02, 95% CI 1.005-1.036, p = 0.0088) were associated with increased risk of RF. Thirty-eight patients (61% of all RFs) underwent revision surgery. Bilateral RF was predictive of revision surgery (HR 3.52, 95% CI 1.8-6.9, p = 0.0002), while patients with unilateral nondisplaced RFs were less likely to require revision (HR 0.39, 95% CI 0.18-0.84, p = 0.016).

CONCLUSIONS

This study provides what is to the authors' knowledge the highest-quality data to date on RF rates following ASLS surgery. At a median follow-up of 5.1 years, 38.8% of patients had at least one RF. Estimated RF rates at 2, 4, 5, and 8 years after surgery were 11%, 24%, 35%, and 49%, respectively. Greater estimated blood loss and postoperative pelvic tilt were significant risk factors for RF. These findings emphasize the importance of long-term follow-up to realize the true prevalence and cumulative incidence of RF.

Development and internal validation of predictive models to assess risk of post-acute care facility discharge in adults undergoing multi-level instrumented fusions for lumbar degenerative pathology and spinal deformity

PURPOSE

To develop a model for factors predictive of Post-Acute Care Facility (PACF) discharge in adult patients undergoing elective multi-level (≥ 3 segments) lumbar/thoracolumbar spinal instrumented fusions.

METHODS

The State Inpatient Databases acquired from the Healthcare Cost and Utilization Project from 2005 to 2013 were queried for adult patients who underwent elective multi-level thoracolumbar fusions for spinal deformity. Outcome variables were classified as discharge to home or PACF. Predictive variables included demographic, pre-operative, and operative factors. Univariate and multivariate logistic regression analyses informed development of a logistic regression-based predictive model using seven selected variables. Performance metrics included area under the curve (AUC), sensitivity, and specificity.

RESULTS

Included for analysis were 8866 patients. The logistic model including significant variables from multivariate analysis yielded an AUC of 0.75. Stepwise logistic regression was used to simplify the model and assess number of variables needed to reach peak AUC, which included seven selected predictors (insurance, interspaces fused, gender, age, surgical region, CCI, and revision surgery) and had an AUC of 0.74. Model cut-off for predictive PACF discharge was 0.41, yielding a sensitivity of 75% and specificity of 59%.

CONCLUSIONS

The seven variables associated significantly with PACF discharge (age > 60, female gender, non-private insurance, primary operations, instrumented fusion involving 8+ interspaces, thoracolumbar region, and higher CCI scores) may aid in identification of adults at risk for discharge to a PACF following elective multi-level lumbar/thoracolumbar spinal fusions for spinal deformity. This may in turn inform discharge planning and expectation management.