Sagittal age-adjusted score (SAAS) for adult spinal deformity (ASD) more effectively predicts surgical outcomes and proximal junctional kyphosis than previous classifications

Influence of postoperative coronal malalignment following long-instrumented fusion in patients with adult spinal deformity: evaluation of clinical outcomes and mechanical complications

BACKGROUND CONTEXT

Achieving satisfactory sagittal alignment in patients with adult spinal deformity (ASD) is a major goal of deformity correction, which leads to high health-related quality. However, compared with the literature on sagittal alignment, studies on postoperative coronal malalignment in ASD are limited.

PURPOSE

This study aimed to investigate the impact of coronal malalignment on clinical outcomes and mechanical complications after corrective surgery for ASD.

STUDY DESIGN/SETTING

Retrospective observational study PATIENT SAMPLE: Among patients who underwent deformity correction with ≥5-level fusion to the sacrum, this study focused on those who achieved optimal sagittal correction, defined as a pelvic incidence minus lumbar lordosis (PI-LL) of ≤10° postoperatively.

OUTCOME MEASURES

Incidence of coronal malalignment; clinical outcomes using the visual analog scale (VAS), Oswestry disability index (ODI), and Scoliosis Research Society Outcomes Questionnaire-22 (SRS-22); and mechanical complications such as proximal junctional kyphosis (PJK), proximal junctional failure (PJF), and rod fracture.

METHODS

Coronal malalignment was evaluated using the coronal balance distance (CBD), defined as the horizontal distance between the C7 plumb line and the central sacral vertical line. Postoperative coronal malalignment was classified as CBD > 3 cm. Patients were divided into two groups based on CBD as follows: the coronal balance (CB) group (balanced, CBD < 3 cm) and the coronal imbalance (CI) group (imbalanced, CBD ≥ 3 cm). Clinical outcomes and the incidence of mechanical complications were compared between the groups.

RESULTS

This study included 112 patients, with a mean follow-up duration of 46.8 months. Among them, 24 patients (21.4%) were included in the CI group, with a mean CBD of 3.6 ± 0.4 cm, whereas 88 patients comprised the CB group, with a mean CBD of 1.1 ± 0.7 cm. The back pain VAS scores indicated that the CI group had significantly worse clinical outcomes than the CB group (52.5 ± 19.8 vs. 40.1 ± 24.0, p = 0.022). The appearance domain of the SRS-22 was also significantly lower in the CI group than in the CB group (2.8 ± 0.6 vs. 3.4 ± 0.9, p = 0.002). However, no significant differences in leg pain VAS scores, ODI scores, or other SRS-22 domains, except appearance, were observed between the two groups. The incidences of PJK, PJF, and rod fractures were similar between the groups. However, the rate of revision surgery for rod fractures was significantly higher in the CI group than in the CB group (5/5 in the CI group vs. 5/29 in the CB group, p < 0.001).

CONCLUSIONS

After correction surgery for ASD, coronal malalignment demonstrated an association with increased back pain VAS scores and lower appearance scores on the SRS-22. The incidence of mechanical complications, including PJK, PJF, and rod fractures, was not influenced by coronal alignment. However, coronal malalignment significantly increased the risk of revision surgery for rod fractures.

Have We Made Advancements in Optimizing Surgical Outcomes and Enhancing Recovery for Patients With High-Risk Adult Spinal Deformity Over Time?

BACKGROUND AND OBJECTIVES

The spectrum of patients requiring adult spinal deformity (ASD) surgery is highly variable in baseline (BL) risk such as age, frailty, and deformity severity. Although improvements have been realized in ASD surgery over the past decade, it is unknown whether these carry over to high-risk patients. We aim to determine temporal differences in outcomes at 2 years after ASD surgery in patients stratified by BL risk.

METHODS

Patients ≥18 years with complete pre- (BL) and 2-year (2Y) postoperative data from 2009 to 2018 were categorized as having undergone surgery from 2009 to 2013 [early] or from 2014 to 2018 [late]. High-risk [HR] patients met ≥2 of the criteria: (1) ++ BL pelvic incidence and lumbar lordosis or SVA by Scoliosis Research Society (SRS)-Schwab criteria, (2) elderly [≥70 years], (3) severe BL frailty, (4) high Charlson comorbidity index, (5) undergoing 3-column osteotomy, and (6) fusion of >12 levels, or >7 levels for elderly patients. Demographics, clinical outcomes, radiographic alignment targets, and complication rates were assessed by time period for high-risk patients.

RESULTS

Of the 725 patients included, 52% (n = 377) were identified as HR. 47% (n = 338) had surgery pre-2014 [early], and 53% (n = 387) underwent surgery in 2014 or later [late]. There was a higher proportion of HR patients in Late group (56% vs 48%). Analysis by early/late status showed no significant differences in achieving improved radiographic alignment by SRS-Schwab, age-adjusted alignment goals, or global alignment and proportion proportionality by 2Y (all P > .05). Late/HR patients had significantly less poor clinical outcomes per SRS and Oswestry Disability Index (both P < .01). Late/HR patients had fewer complications (63% vs 74%, P = .025), reoperations (17% vs 30%, P = .002), and surgical infections (0.9% vs 4.3%, P = .031). Late/HR patients had lower rates of early proximal junctional kyphosis (10% vs 17%, P = .041) and proximal junctional failure (11% vs 22%, P = .003).

CONCLUSION

Despite operating on more high-risk patients between 2014 and 2018, surgeons effectively reduced rates of complications, mechanical failures, and reoperations, while simultaneously improving health-related quality of life.

What if You Could Treat the Same Patient Again, Would You do the Exact Same Spine Surgery? A Multi-Surgeon Survey of Their Own Revisions

Study DesignCase-based survey.ObjectivesThis study aims to investigate what a group of surgeons learned from their own revisions, and what they would do differently today.MethodsA multi-center database of ASD surgical patients was queried to identify those with at least 2 surgical procedures performed by the same surgeon between 2009 and 2019. A clinical vignette was created for each case including demographics, a timeline of events, radiographs/measurements, patient-reported outcomes, complications, and surgical strategies used for the index and revision surgeries. The operative surgeon was then asked to fill out a five-question survey aimed at determining factors that contribute to operative decision-making and planning.Results86 patients were operated on by 6 participating surgeons for both index and revision ASD surgery. The revised patients had similar follow-up compared to the non-revised group (P = 0.73), with the most common complications indicating a need for revision surgery being proximal junctional failure (42%) and pseudoarthrosis (28%). Surgeons reported that they would not change their surgical strategy in 52.3% of the cases. The leading cause for revision was hardware/instrumentation issues (24.4%). Learning points included rod-related choice (23.3%), level selection (19.8), PJF prophylactic strategy (15.1%), and sagittal alignment objective (11.6%).ConclusionsSurgeons saw opportunity in nearly half of the cases to improve outcomes by changing something in the original surgery. While 40% of the failures remained unexplained from the surgeons' perspective, this study highlights the capacity for adopting changes in adult spinal deformity surgery and illuminates the reasoning behind certain surgical decisions.

Despite a Multifactorial Etiology, Rates of Distal Junctional Kyphosis After Adult Cervical Deformity Corrective Surgery Can be Dramatically Diminished by Optimizing Age Specific Radiographic Improvement

Study DesignRetrospective cohort study of a prospectively collected single-center database.ObjectiveDistal Junctional Kyphosis (DJK) is one of the most common complications in adult cervical deformity (ACD) correction. The utility of radiographic alignment alone in predicting and minimizing DJK occurrence warrants further study. To investigate the impact of post-operative radiographic alignment on development of DJK in ACD patients.MethodsACD patients (≥18 yrs) with complete baseline (BL) and two-year (2Y) radiographic data were included. DJF was defined as DJK greater than 15° (Passias et al) or DJK with reop. Multivariable logistic regression (MVA) identified 3-month predictors of DJK. Conditional inference tree (CIT) machine learning analysis determined threshold cutoffs. Radiographic predictors were combined in a model to determine predictive value using area under the curve (AUC) methodology. "Match" refers to ideal age-adjusted alignment.Results140 cervical deformity patients met inclusion criteria (61.3 yrs, 67% F, BMI: 29 kg/m2, CCI: 0.96 ± 1.3). Surgically, 51.3% had osteotomies, 47.1% had a posterior approach, 34.5% combined approach, 18.5% anterior approach, with an average 7.6 ± 3.8 levels fused and EBL of 824 mL. Overall, 33 patients (23.6%) developed DJK, and 11 patients (9%) developed DJF. MVA controlling for age, and baseline deformity, followed by CIT found 3M cSVA <3.7 cm (OR: .2, 95% CI:.06-.6), and TK T4-T12 <50 (OR:.17, 95% CI:.05-.5, both P < .05) were significant predictors of a lower likelihood of DJK. Receiver operator curve AUC using age, T1S match, TS-CL match, LL-TK match, cSVA <3.7 cm, and T4-T12 <50 predicted DJK with an AUC of .91 for DJK by 2Y, and .88 for DJF by 2Y.ConclusionThese findings suggest post-operative radiographic alignment is strongly associated with distal junctional kyphosis. When utilizing age-adjusted realignment in addition to newly developed thresholds, a suggested post-operative cSVA target of 3.7 cm and thoracic kyphosis less than 50, it is possible to substantially reduce the occurrence of distal junctional kyphosis and distal junctional failure.

Relationship of T10-Pelvic Angle With Conventional Sagittal Parameters and Legacy Alignment Schemes in Adult Spinal Deformity Surgery

Study DesignRetrospective analysis.ObjectiveTo investigate the relationship of T10-pelvic angle (T10PA) with conventional sagittal parameters and legacy alignment schemes.Summary of Background DataT10PA is a newly introduced sagittal parameter to predict the development of proximal junctional kyphosis (PJK). However, its relationship with conventional sagittal parameters and legacy alignment schemes remains unknown.MethodsPatients with fusion from the pelvis to the upper-instrumented vertebra at or above the T10 were included. Based on the 6-week T10PA, the patients were divided into 3 groups as follows: undercorrection, functional alignment, and overcorrection. Conventional sagittal parameters and alignment status based on the Schwab's pelvic incidence (PI)-lumbar lordosis (LL) modifiers and age-adjusted PI-LL were compared according to the T10PA groups. The PJK rates were compared among the alignment schemes.ResultsOverall, 219 patients were enrolled in this study. At 6 weeks postoperatively, 33.3%, 37.0%, and 29.7% of the patients demonstrated undercorrection, functional alignment, and overcorrection relative to the T10PA, respectively. Conventional sagittal parameters significantly differed according to the T10PA groups. Linear regression analysis revealed that T10PA was significantly affected by PI (β = .562) and LL (β = - .411). The correction statuses of the Schwab's PI-LL modifiers and age-adjusted PI-LL were significantly differentiated between the T10PA correction groups. However, only 32.9% of patients with functional alignment relative to T10PA belonged to matched correction category for the age-adjusted PI-LL. Overcorrection relative to age-adjusted PI-LL and T10PA significantly increased PJK risks.ConclusionT10PA significantly correlated with conventional sagittal parameters, particularly PI and LL. Although the T10PA correction status correlated with that of the legacy alignment schemes, a notable discrepancy in the optimal correction was observed between the T10PA and age-adjusted PI-LL schemes. Overcorrection relative to T10PA and age-adjusted PI-LL should be avoided to mitigate PJK development.

Proximal Junctional Kyphosis and Failure Prophylaxis Improves Cost Efficacy, While Maintaining Optimal Alignment, in Adult Spinal Deformity Surgery

BACKGROUND AND OBJECTIVES

To investigate the cost-effectiveness and impact of prophylactic techniques on the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in the context of postoperative alignment.

METHODS

Adult spinal deformity patients with fusion to pelvis and 2-year data were included. Patients receiving PJK prophylaxis (hook, tether, cement, minimally-invasive surgery approach) were compared to those who did not. These cohorts were further stratified into "Matched" and "Unmatched" groups based on achievement of age-adjusted alignment criteria. Costs were calculated using the Diagnosis-Related Group costs accounting for PJK prophylaxis, postoperative complications, outpatient health care encounters, revisions, and medical-related readmissions. Quality-adjusted life years were calculated using Short Form-36 converted to Short-Form Six-Dimension (SF-6D) and used an annual 3% discount rate. Multivariate analysis controlling for age, sex, levels fused, and baseline deformity severity assessed outcomes of developing PJK/PJF if matched and/or with use of PJK prophylaxis.

RESULTS

A total of 738 adult spinal deformity patients met inclusion criteria (age: 63.9 ± 9.9, body mass index: 28.5 ± 5.7, Charlson comorbidity index: 2.0 ± 1.7). Multivariate analysis revealed patients corrected to age-adjusted criteria postoperatively had lower rates of developing PJK or PJF (odds ratio [OR]: 0.4, [0.2-0.8]; P = .011) with the use of prophylaxis. Among those unmatched in T1 pelvic angle, pelvic incidence lumbar lordosis mismatch, and pelvic tilt, prophylaxis reduced the likelihood of developing PJK (OR: 0.5, [0.3-0.9]; P = .023) and PJF (OR: 0.1, [0.03-0.5]; P = .004). Analysis of covariance analysis revealed patients matched in age-adjusted alignment had better cost-utility at 2 years compared with those without prophylaxis ($361 539.25 vs $419 919.43; P < .001). Patients unmatched in age-adjusted criteria also generated better cost ($88 348.61 vs $101 318.07; P = .005) and cost-utility ($450 190.80 vs $564 108.86; P < .001) with use of prophylaxis.

CONCLUSION

Despite additional surgical cost, the optimization of radiographic realignment in conjunction with prophylaxis of the proximal junction appeared to be a more cost-effective strategy, primarily because of the minimization of reoperations secondary to mechanical failure. Even among those not achieving optimal alignment, junctional prophylactic measures were shown to improve cost efficiency.

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

STUDY DESIGN

This is a retrospective study.

OBJECTIVE

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

SUMMARY OF BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Machine-learning models for the prediction of ideal surgical outcomes in patients with adult spinal deformity

Aims

Adult spinal deformity (ASD) surgery can reduce pain and disability. However, the actual surgical efficacy of ASD in doing so is far from desirable, with frequent complications and limited improvement in quality of life. The accurate prediction of surgical outcome is crucial to the process of clinical decision-making. Consequently, the aim of this study was to develop and validate a model for predicting an ideal surgical outcome (ISO) two years after ASD surgery.

Methods

We conducted a retrospective analysis of 458 consecutive patients who had undergone spinal fusion surgery for ASD between January 2016 and June 2022. The outcome of interest was achievement of the ISO, defined as an improvement in patient-reported outcomes exceeding the minimal clinically important difference, with no postoperative complications. Three machine-learning (ML) algorithms - LASSO, RFE, and Boruta - were used to identify key variables from the collected data. The dataset was randomly split into training (60%) and test (40%) sets. Five different ML models were trained, including logistic regression, random forest, XGBoost, LightGBM, and multilayer perceptron. The primary model evaluation metric was area under the receiver operating characteristic curve (AUROC).

Results

The analysis included 208 patients (mean age 64.62 years (SD 8.21); 48 male (23.1%), 160 female (76.9%)). Overall, 42.8% of patients (89/208) achieved the ideal surgical outcome. Eight features were identified as key variables affecting prognosis: depression, osteoporosis, frailty, failure of pelvic compensation, relative functional cross-sectional area of the paraspinal muscles, postoperative sacral slope, pelvic tilt match, and sagittal age-adjusted score match. The best prediction model was LightGBM, achieving the following performance metrics: AUROC 0.888 (95% CI 0.810 to 0.966); accuracy 0.843; sensitivity 0.829; specificity 0.854; positive predictive value 0.806; and negative predictive value 0.872.

Conclusion

In this prognostic study, we developed a machine-learning model that accurately predicted outcome after surgery for ASD. The model is built on routinely modifiable indicators, thereby facilitating its integration into clinical practice to promote optimized decision-making.

Analysis of Personalized Interbody Implants in the Surgical Treatment of Adult Spinal Deformity

STUDY DESIGN

Multicenter cohort.

OBJECTIVES

A report from the International Spine Study Group (ISSG) noted that surgeons failed to achieve alignment goals in nearly two-thirds of 266 complex adult deformity surgery (CADS) cases. We assess whether personalized interbody spacers are associated with improved rates of achieving goal alignment following adult spinal deformity (ASD) surgery.

METHODS

ASD patients were included if their surgery utilized 3D-printed personalized interbody spacer(s) and they met ISSG CADS inclusion criteria. Planned alignment was personalized by the surgeon during interbody planning. Planned vs achieved alignment was assessed and compared with the ISSG CADS series that used stock interbodies.

RESULTS

For 65 patients with personalized interbodies, 62% were women, mean age was 70.3 years (SD = 8.3), mean instrumented levels was 9.9 (SD = 4.1), and the mean number of personalized interbodies per patient was 2.2 (SD = .8). Segmental alignment was achieved close to plan for levels with personalized interbodies, with mean difference between goal and achieved as follows: intervertebral lordosis = .9° (SD = 5.2°), intervertebral coronal angle = .1° (SD = 4.7°), and posterior disc height = -0.1 mm (SD = 2.3 mm). Achieved pelvic incidence-to-lumbar lordosis mismatch (PI-LL) correlated significantly with goal PI-LL (r = .668, P < .001). Compared with the ISSG CADS cohort, utilization of personalized interbodies resulted in significant improvement in achieving PI-LL <5° of plan (P = .046) and showed a significant reduction in cases with PI-LL >15° of plan (P = .012).

CONCLUSIONS

This study supports use of personalized interbodies as a means of better achieving goal segmental sagittal and coronal alignment and significantly improving achievement of goal PI-LL compared with stock devices.

Adult Cervical Deformity Patients Have Higher Baseline Frailty, Disability, and Comorbidities Compared With Complex Adult Thoracolumbar Deformity Patients: A Comparative Cohort Study of 616 Patients

STUDY DESIGN

Multicenter comparative cohort.

OBJECTIVE

Studies have shown markedly higher rates of complications and all-cause mortality following surgery for adult cervical deformity (ACD) compared with adult thoracolumbar deformity (ATLD), though the reasons for these differences remain unclear. Our objectives were to compare baseline frailty, disability, and comorbidities between ACD and complex ATLD patients undergoing surgery.

METHODS

Two multicenter prospective adult spinal deformity registries were queried, one ATLD and one ACD. Baseline clinical and frailty measures were compared between the cohorts.

RESULTS

616 patients were identified (107 ACD and 509 ATLD). These groups had similar mean age (64.6 vs 60.8 years, respectively, P = .07). ACD patients were less likely to be women (51.9% vs 69.5%, P < .001) and had greater Charlson Comorbidity Index (1.5 vs .9, P < .001) and ASA grade (2.7 vs 2.4, P < .001). ACD patients had worse VR-12 Physical Component Score (PCS, 25.7 vs 29.9, P < .001) and PROMIS Physical Function Score (33.3 vs 35.3, P = .031). All frailty measures were significantly worse for ACD patients, including hand dynamometer (44.6 vs 55.6 lbs, P < .001), CSHA Clinical Frailty Score (CFS, 4.0 vs 3.2, P < .001), and Edmonton Frailty Scale (EFS, 5.15 vs 3.21, P < .001). Greater proportions of ACD patients were frail (22.9% vs 5.7%) or vulnerable (15.6% vs 10.9%) based on EFS (P < .001).

CONCLUSIONS

Compared with ATLD patients, ACD patients had worse baseline characteristics on all measures assessed (comorbidities/disability/frailty). These differences may help account for greater risk of complications and all-cause mortality previously observed in ACD patients and facilitate strategies for better preoperative optimization.

An analysis of the usage and limitations of the T1 pelvic angle

Aims

The T1 pelvic angle (T1PA) provides a consistent global measure of sagittal alignment independent of compensatory mechanisms and positional changes. However, it may not explicitly reflect alignment goals that correlate with a lower risk of complications. This study assessed the value of T1PA in achieving sagittal alignment goals in patients with an adult spinal deformity (ASD).

Methods

Patients aged ≥ 18 years who had undergone surgery for ASD and had complete baseline data and at least two-year postoperative, radiological, and health-related quality of life follow-up were included. A total of 596 patients met the inclusion criteria (mean age 61.5 years (SD 13.4); 78.8% females; mean BMI 27.8 kg/m2 (SD 5.9); mean Charlson Comorbidity Index 1.9 (SD 1.8)). The primary outcome was development of mechanical complications. Cohorts were based on postoperative T1PA (T1PA < 10° or > 30° = unfavourable vs T1PA 10° to 30° = favourable). Adjustments for confounders with separate analyses were done using multivariable logistic regression analysis.

Results

Postoperatively, 363 patients (60.9%) had a favourable T1PA and 233 (39.1%) did not. Those with a favourable T1PA had a significantly higher rate of proximal junctional kyphosis (PJK) than those with an unfavourable T1PA (52.0% vs 48.0%; p = 0.035). Having adjusted for confounders, those with a favourable T1PA had a decreased risk of proximal junctional kyphosis (OR 0.532 (95% CI 0.288 to 0.985); p = 0.045).

Conclusion

The T1PA gives valuable information about global alignment, but fails to recognize and adjust for the great variation in patients with ASD. As such, we recommend combining the T1PA with alternative alignment strategies to better inform clinical care.

Anterior Versus Posterior Lumbar Interbody Fusion at L5-S1 in Hybrid Surgery for Adult Spinal Deformity: A Propensity Score Matching Analysis of Radiographic Results, Mechanical Complications, and Clinical Outcomes

Objectives: The aim of this study was to compare the radiographic results, mechanical complications, and clinical outcomes between anterior and posterior lumbar interbody fusion at L5-S1 (ALIF51 and PLIF51 groups, respectively) using a matched cohort of patients undergoing long fusion for adult spinal deformity (ASD). Methods: Patients who underwent hybrid surgery of ≥5-level fusion to the pelvis with a minimum follow-up duration of 2 years were included. The baseline characteristics of the groups were controlled using a propensity score matching analysis. The radiographic results, mechanical complications such as proximal junctional kyphosis/failure and metal failure, and clinical outcomes were compared between the groups. Results: In total, 79 patients were assigned to each group with comparable baseline data, except for a higher frequency of anterior column realignment procedures in the PLIF51 group than in the ALIF51 group (49.4% vs. 31.6%). At the last follow-up, L5-S1 segmental lordosis (SL) was significantly greater in the ALIF51 group than in the PLIF51 group (12.1° vs. 7.3°, p < 0.001). The final C7-sagittal vertical axis (SVA) was significantly smaller in the ALIF51 group than in the PLIF51 group (25.4 mm vs. 35.5 mm, p = 0.032). However, other global sagittal parameters were comparable between the groups. The mechanical complication rates, including metal failure at L5-S1, and the final clinical outcomes were comparable between the groups. Conclusions: ALIF51 has modest advantages over PLIF51 in terms of better restoring L5-S1 SL and C7-SVA with avoiding more invasive procedures above the L5-S1 levels. Other sagittal parameters, mechanical complication rates, and clinical outcomes did not differ between the groups.

The role of supine imaging in assessing failure of pelvic compensation and its impact on surgical outcomes in patients with adult spinal deformity

AIMS

This study aims to investigate the impacts of failure of pelvic compensation (FPC), as determined by variations in spinopelvic alignment during the transition from the supine to the upright position, on surgical outcomes in patients with adult spinal deformity (ASD).

METHODS

A total of 125 ASD patients who underwent posterior correction surgery with a minimum follow-up of two years were enrolled. Radiographic outcomes, including thoracic kyphosis, lumbar lordosis, sacral slope (SS), pelvic tilt (PT), pelvic incidence, T1-pelvic-angle and sagittal vertical axis (SVA), were measured on lateral whole-spine radiographs. Postoperative realignment was assessed using the sagittal age-adjusted score (SAAS). Patient-reported outcomes were collected through Scoliosis Research Society-22R (SRS-22R) questionnaire, alongside data on minimum clinically important difference (MCID) achievement. The incidence of proximal junctional kyphosis (PJK) following surgery was also recorded. Based on the calculated minimum detectable change of SS, FPC was defined as the change in SS of less than 3.9° between supine and upright positions. Patients were divided into the pelvic compensation (PC) cohort and the FPC cohort.

RESULTS

Eighty-eight patients were categorized into the PC cohort and 37 into the FPC cohort. Postoperatively, patients with FPC exhibited significantly lower PT (22.44° vs. 28.57°, p <.001) and higher SVA (57.49 mm vs. 32.57 mm, p =.008) than PC patients. Additionally, the SRS-22R subtotal score was lower in the FPC group (3.68 vs. 3.89, p =.035), and the proportion of MCID achievement in SRS-22R was significantly reduced (45.95% vs. 65.91%, p =.038). While the incidence of PJK was higher in FPC patients, this difference was not significant (40.54% vs. 29.55%, p =.232). Correcting to SAAS matching standard was associated with a reduced risk of PJK (OR 6.50, 95%CI 1.18-35.84) and increased likelihood of achieving MCID (OR 4.50, 95%CI 1.05-19.22) in ASD patients with FPC.

CONCLUSION

ASD patients with preoperative FPC are more likely to experience worse patient-reported outcomes and a higher incidence of mechanical complications following corrective surgery. To optimize surgical outcomes in these patients, individualized preoperative planning aligned with the SAAS criteria may be particularly beneficial.

Effects of Transverse Process Hook Fixation for Preventing Proximal Junctional Kyphosis/Failure in Adult Spinal Deformity Surgery: A Multiple Regression Analysis Adjusting for Confounding Factors

STUDY DESIGN

Retrospective study.

OBJECTIVES

To investigate the effects of transverse process hook (TPH) at the uppermost instrumented vertebra (UIV) + 1 on the prevention of proximal junctional kyphosis/failure (PJK/F) following adult spinal deformity (ASD) surgery.

METHODS

We included patients who underwent fusion of the lower thoracic spine (T8-T11) to the sacrum for ASD. The patients were divided into the non-TPH and TPH groups. PJK and PJF were defined as proximal junctional angle >20° and any cases requiring revision surgery. Multiple regression analysis was performed, including surgical techniques (non-use of TPH vs TPH) and confounding variables.

RESULTS

Altogether, 153 patients were included in the study (women, 91.5%; mean age, 69.2 years; total levels fused, 8.5). The non-TPH and TPH groups comprised 88 and 65 patients. Unadjusted bivariate analysis showed that the TPH did not significantly affect the risk of PJK and PJF. However, multiple regression analysis revealed that the non-use of TPH was associated with an increased risk of developing PJK and PJF (odds ratio [OR] = 3.079, P = 0.029 for PJK; OR = 6.363, P = 0.049 for PJF). In patients who underwent TPH fixation, confounder-adjusted regression analysis showed that two-level TPH fixation did not further decrease the risk of PJK/F.

CONCLUSIONS

The preventive effect of TPH against PJK/F development was not significant in the unadjusted bivariate analysis. However, multiple regression analysis adjusted for the confounding factors demonstrated that TPH fixation at the UIV +1 significantly decreased the risk of PJK and PJF.

Hook Fixation at Uppermost Instrumented Vertebra +1 Reduced Proximal Junctional Failure in Adult Patients With Spinal Deformity Having Achieved Optimal Deformity Correction by Sagittal Age-Adjusted Score

BACKGROUND AND OBJECTIVES

Appropriate correction relative to the age-adjusted sagittal alignment target reduces the proximal junctional failure (PJF) risk. Nonetheless, a considerable number of patients suffer from PJF despite optimal correction. The aim of this study was to identify the risk factors of PJF that occurs despite optimal correction relative to the sagittal age-adjusted score (SAAS) in adult spinal deformity surgery.

METHODS

Patients aged 60 years or older with adult spinal deformity who underwent ≥5-level fusion to the sacrum were initially screened. Among them, only patients who achieved optimal sagittal correction relative to the SAAS were included in the study. Optimal correction was defined as the SAAS point between -1 and +1. Various clinical and radiographic factors were compared between the PJF and no PJF groups and were further evaluated using multivariate analysis.

RESULTS

The final study cohort comprised 127 patients. The mean age was 67 years, and there were 111 women (87.4%). A mean of total fusion length was 7.2. PJF occurred in 42 patients (33.1%), while 85 patients (66.9%) did not develop PJF. Multivariate analysis showed that a high body mass index (odds ratio [OR] = 1.153, 95% CI = 1.027-1.295, P = .016), a higher lordosis distribution index (LDI) (OR = 1.024, 95% CI = 1.003-1.045, P = .022), and no use of hook fixation (OR = 9.708, 95% CI = 1.121-76.923, P = .032) were significant risk factors of PJF development. In the receiver operating characteristic curve analysis, the cutoff value for the LDI was calculated as 61.0% (area under the curve = 0.790, P < .001).

CONCLUSION

PJF developed in a considerable portion of patients despite optimal correction relative to the age-adjusted alignment. The risk factors of PJF in this patient group were high body mass index, high LDI exceeding 61%, and no use of hook fixation. PJF could be further decreased by properly managing these risk factors along with optimal sagittal correction.

Risk Factors of Proximal Junctional Failure After Adult Spinal Deformity Surgery: A Systematic Review and Meta-Analysis

OBJECTIVE

This study aimed to identify surgical, patient-specific, and radiographic risk factors for proximal junctional failure (PJF), a complex complication following adult spinal deformity (ASD) surgery.

METHODS

A systematic literature search was performed using PubMed, Embase, and the Cochrane Library. The literature on the risk factors for PJF after ASD surgery was included. The study patients were diagnosed with ASD and underwent surgery for ASD. PJF is defined as the occurrence of proximal junctional kyphosis, accompanied by one or more of the following characteristics: a fracture of the vertebral body at the upper instrumented vertebra (UIV) or UIV + 1 level, disruption of the posterior ligaments, or dislodgement of the instrumentation at the UIV. proximal junctional kyphosis, on the other hand, is determined by 2 criteria: a proximal junctional sagittal Cobb angle 1) of 10° and 2) at least 10° greater than the preoperative value.

RESULTS

Our pooled analysis of 11 unique studies (2037 patients) revealed significant differences in several preoperative and postoperative measures between PJF and non-PJF groups.

CONCLUSIONS

In ASD patients, the presence of concurrent osteoporosis or paravertebral muscle wasting significantly increases the risk of developing PJF. The use of bicortical screws, UIV screw angle exceeding 1°, and positioning the UIV in the lower thoracic or lumbar region also further elevate this risk. Lower preoperative SS, higher preoperative PI-LL, higher preoperative pelvic tilt, higher preoperative SVA, higher postoperative LL, and a greater change in LL characterize patients with PJF.

Comparative Analysis of Outcomes in Adult Spinal Deformity Patients with Proximal Junctional Kyphosis or Failure Initially Fused to Upper Versus Lower Thoracic Spine

Background: Patients with proximal junctional kyphosis (PJK) or failure (PJF) may demonstrate disparate outcomes and recovery when fused to the upper (UT) versus lower (LT) thoracic spine. Few studies have distinguished the reoperation and recovery abilities of patients with PJK or PJF when fused to the upper (UT) versus lower (LT) thoracic spine. Methods: Adult spine deformity patients ≥ 18 yrs with preoperative and 5-year (5Y) data fused to the sacrum/pelvis were included. The rates of PJK, PJK revision, and radiographic PJF were compared between patients with upper instrumented vertebra (UIV) in the upper thoracic spine (UT; T1-T7) and lower thoracic spine (LT; T8-L1). Mean differences were assessed via analyses of covariance, factoring in any differences between cohorts at baseline and any use of PJF prophylaxis. Backstep logistic regressions assessed predictors of achieving Smith et al.'s Best Clinical Outcomes (BCOs) and complications, controlling for similar covariates. Results: A total of 232 ASD patients were included (64.2 ± 10.2 years, 78% female); 36.3% were UT and 63.7% were LT. Postoperatively, the rates of PJK for UT were lower than LT at 1Y (34.6 vs. 50.4%, p = 0.024), 2Y (29.5 vs. 49.6% (p = 0.003), and 5Y (48.7 vs. 62.8%, p = 0.048), with comparable rates of PJF. In total, 4.0% of UT patients underwent subsequent reoperation, compared to 13.0% of LT patients (p = 0.025). A total of 6.0% of patients had recurrent PJK, and 3.9% had recurrent PJF (both p > 0.05). After reoperation, UT patients reported higher rates of improvement in the minimum clinically important difference for ODI by 2Y (p = 0.007) and last follow-up (p < 0.001). While adjusted regression revealed that, for UT patients, the minimization of construct extension was predictive of achieving BCOs by last follow-up (model p < 0.001), no such relationship was identified in LT patients. Conclusions: Patients initially fused to the lower thoracic spine demonstrate an increased incidence of PJK and lower rates of disability improvement, but are at a lessened risk of neurologic complications if reoperation is required.

Prediction of postoperative mechanical complications in ASD patients based on total sequence and proportional score of spinal sagittal plane

This article aimed to predict the occurrence of postoperative mechanical complications in adult spinal deformity (ASD) patients through the total sequence and proportional score of the spinal sagittal plane, to improve the quality of life of patients after surgery. The study adopted a comprehensive evaluation and data analysis method, including data collection and preprocessing, feature selection, model construction and training, and constructed a prediction model based on the Random Forest (RF) algorithm. The experimental results showed that the model significantly reduced the risk of complications in randomized controlled trials. The incidence of mechanical complications in the experimental group was 10 %, while that in the control group was 25 %, with statistical significance (P < 0.05). In addition, in retrospective data analysis, the accuracy of the article's model on five datasets ranged from 89 % to 93 %, outperforming logistic regression and support vector machine models, and performing well on other performance data. In prospective studies, the model's predictions showed good consistency with the actual occurrence of complications. Sensitivity analysis shows that the model has low sensitivity to changes in key parameters and exhibits stability, indicating that the model proposed in this article is suitable for uncertain medical environments. The expert rating further confirmed the effectiveness and practicality of the model in predicting postoperative mechanical complications in ASD patients, with the highest score reaching 4.9. These data demonstrate the high accuracy and clinical potential of the model in predicting postoperative complications of ASD.

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.

Frail patients require instrumentation of a more proximal vertebra for a successful outcome after surgery for adult spine deformity

Aims

The aim of this study was to investigate the impact of the level of upper instrumented vertebra (UIV) in frail patients undergoing surgery for adult spine deformity (ASD).

Methods

Patients with adult spinal deformity who had undergone T9-to-pelvis fusion were stratified using the ASD-Modified Frailty Index into not frail, frail, and severely frail categories. ASD was defined as at least one of: scoliosis ≥ 20°, sagittal vertical axis (SVA) ≥ 5 cm, or pelvic tilt ≥ 25°. Means comparisons tests were used to assess differences between both groups. Logistic regression analyses were used to analyze associations between frailty categories, UIV, and outcomes.

Results

A total of 477 patients were included (mean age 60.3 years (SD 14.9), mean BMI 27.5 kg/m2 (SD 5.8), mean Charlson Comorbidity Index (CCI) 1.67 (SD 1.66)). Overall, 74% of patients were female (n = 353), and 49.6% of patients were not frail (237), 35.4% frail (n = 169), and 15% severely frail (n = 71). At baseline, differences in age, BMI, CCI, and deformity were significant (all p = 0.001). Overall, 15.5% of patients (n = 74) had experienced mechanical complications by two years (8.1% not frail (n = 36), 15.1% frail (n = 26), and 16.3% severely frail (n = 12); p = 0.013). Reoperations also differed between groups (20.2% (n = 48) vs 23.3% (n = 39) vs 32.6% (n = 23); p = 0.011). Controlling for osteoporosis, baseline deformity, and degree of correction (by sagittal age-adjusted score (SAAS) matching), frail and severely frail patients were more likely to experience mechanical complications if they had heart failure (odds ratio (OR) 6.6 (95% CI 1.6 to 26.7); p = 0.008), depression (OR 5.1 (95% CI 1.1 to 25.7); p = 0.048), or cancer (OR 1.5 (95% CI 1.1 to 1.4); p = 0.004). Frail and severely frail patients experienced higher rates of mechanical complication than 'not frail' patients at two years (19% (n = 45) vs 11.9% (n = 29); p = 0.003). When controlling for baseline deformity and degree of correction in severely frail and frail patients, severely frail patients were less likely to experience clinically relevant proximal junctional kyphosis or failure or mechanical complications by two years, if they had a more proximal UIV.

Conclusion

Frail patients are at risk of a poor outcome after surgery for adult spinal deformity due to their comorbidities. Although a definitively prescriptive upper instrumented vertebra remains elusive, these patients appear to be at greater risk for a poor outcome if the upper instrumented vertebra is sited more distally.

The Incremental Clinical Benefit of Adding Layers of Complexity to the Planning and Execution of Adult Spinal Deformity Corrective Surgery

BACKGROUND AND OBJECTIVES

For patients with surgical adult spinal deformity (ASD), our understanding of alignment has evolved, especially in the last 20 years. Determination of optimal restoration of alignment and spinal shape has been increasingly studied, yet the assessment of how these alignment schematics have incrementally added benefit to outcomes remains to be evaluated.

METHODS

Patients with ASD with baseline and 2-year were included, classified by 4 alignment measures: Scoliosis Research Society (SRS)-Schwab, Age-Adjusted, Roussouly, and Global Alignment and Proportion (GAP). The incremental benefits of alignment schemas were assessed in chronological order as our understanding of optimal alignment progressed. Alignment was considered improved from baseline based on SRS-Schwab 0 or decrease in severity, Age-Adjusted ideal match, Roussouly current (based on sacral slope) matching theoretical (pelvic incidence-based), and decrease in proportion. Patients separated into 4 first improving in SRS-Schwab at 2-year, second Schwab improvement and matching Age-Adjusted, third two prior with Roussouly, and fourth improvement in all four. Comparison was accomplished with means comparison tests and χ 2 analyses.

RESULTS

Sevenhundredthirty-two. patients met inclusion. SRS-Schwab BL: pelvic incidence-lumbar lordosis mismatch (++:32.9%), sagittal vertical axis (++: 23%), pelvic tilt (++:24.6%). 640 (87.4%) met criteria for first, 517 (70.6%) second, 176 (24%) third, and 55 (7.5%) fourth. The addition of Roussouly (third) resulted in lower rates of mechanical complications and proximal junctional kyphosis (48.3%) and higher rates of meeting minimal clinically important difference (MCID) for physical component summary and SRS-Mental ( P < .05) compared with the second. Fourth compared with the third had higher rates of MCID for ODI (44.2% vs third: 28.3%, P = .011) and SRS-Appearance (70.6% vs 44.8%, P < .001). Mechanical complications and proximal junctional kyphosis were lower with the addition of Roussouly ( P = .024), while the addition of GAP had higher rates of meeting MCID for SRS-22 Appearance ( P = .002) and Oswestry Disability Index ( P = .085).

CONCLUSION

Our evaluation of the incremental benefit that alignment schemas have provided in ASD corrective surgery suggests that the addition of Roussouly provided the greatest reduction in mechanical complications, while the incorporation of GAP provided the most significant improvement in patient-reported outcomes.

Factors Associated With the Maintenance of Cost-effectiveness at Five Years in Adult Spinal Deformity Corrective Surgery

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To evaluate factors associated with the long-term durability of cost-effectiveness (CE) in ASD patients.

BACKGROUND

A substantial increase in costs associated with the surgical treatment for adult spinal deformity (ASD) has given precedence to scrutinize the value and utility it provides.

METHODS

We included 327 operative ASD patients with five-year (5 yr) follow-up. Published methods were used to determine costs based on CMS.gov definitions and were based on the average DRG reimbursement rates. The utility was calculated using quality-adjusted life-years (QALY) utilizing the Oswestry Disability Index (ODI) converted to Short-Form Six-Dimension (SF-6D), with a 3% discount applied for its decline in life expectancy. The CE threshold of $150,000 was used for primary analysis.

RESULTS

Major and minor complication rates were 11% and 47%, respectively, with 26% undergoing reoperation by five years. The mean cost associated with surgery was $91,095±$47,003, with a utility gain of 0.091±0.086 at one years, QALY gained at 2 years of 0.171±0.183, and at five years of 0.42±0.43. The cost per QALY at two years was $414,885, which decreased to $142,058 at five years.With the threshold of $150,000 for CE, 19% met CE at two years and 56% at five years. In those in which revision was avoided, 87% met cumulative CE till life expectancy. Controlling analysis depicted higher baseline CCI and pelvic tilt (PT) to be the strongest predictors for not maintaining durable CE to five years [CCI OR: 1.821 (1.159-2.862), P =0.009] [PT OR: 1.079 (1.007-1.155), P =0.030].

CONCLUSIONS

Most patients achieved cost-effectiveness after four years postoperatively, with 56% meeting at five years postoperatively. When revision was avoided, 87% of patients met cumulative cost-effectiveness till life expectancy. Mechanical complications were predictive of failure to achieve cost-effectiveness at two years, while comorbidity burden and medical complications were at five years.

The more the better? Integration of vertebral pelvic angles (VPA) PJK thresholds to existing alignment schemas for prevention of mechanical complications after adult spinal deformity surgery

PURPOSE

While existing adult spinal deformity (ASD) alignment schemas acknowledge the dynamic relationship between the pelvis and spine, consideration of vertebral pelvic angles (VPA) thresholds for PJK may provide further insight into the relationship of each individual vertebra to the pelvis, which may allow for greater individualization of operative targets. Herein, we examine VPA's utility in preventing mechanical complications and its possible unification with prevalent scoring systems.

METHODS

In a retrospective cohort study of a prospectively collected database, operative ASD patients ≥ 18 years with complete baseline (BL) and two-year (Y) operative, radiographic, and health-related quality of life data were included. Descriptive analyses, means comparison, and logistic regression tests were applied to explore demographic and surgical differences, as well as the impact of alignment goals on outcomes. Cohorts were grouped as patients who met VPA non-PJK thresholds, as defined by Duvvuri et al. 2023 alone versus traditional GAP/SAAS alignment matching versus combined VPA + SAAS + GAP. The Non-PJK VPA validated mean for L1PA was 10.4 ± 7.0 and T9PA 8.9 ± 7.5.

RESULTS

398 patients met inclusion criteria (mean age 61 ± 14 years, 78% female, BL BMI 27 ± 6, BL CCI 2 ± 2). At baseline, mean vertebral pelvic angles were as follows: T1PA: 24 ± 14; T4PA 20 ± 13, T9PA 15 ± 12, L1PA 11 ± 10, L4PA 11 ± 6. Mean vertebral pelvic angles at 6 W postoperatively: T1PA 16 ± 10, T4PA 12 ± 10, T9PA 8 ± 9, L1PA 9 ± 8, L4PA 11 ± 5. 240 (60%) patients attained optimal L1PA, while 104 patients (26.1%) reached non-PJK mean for T9PA. 89 patients (22%) were optimal by both VPA standards. VPA-Optimal group demonstrated significantly lower rates of 1Y PJK (17% v 83%, p = 0.042) and PJF by 2Y (7% v. 93%, p = 0.038). When patients attained VPA goals in addition to GAP/SAAS goals at 6 W, they demonstrated significantly lower rates of Y1 PJK (p = 0.026) and Y1 and Y2 PJF. Those with optimal VPA registered greater SRS-22 scores across multiple domains (p < 0.02) as well as a greater rate of normal neurological examination at 6 W (p = 0.048).

CONCLUSIONS

Vertebral pelvic angles are a reliable measure of global alignment, and respecting certain targets may help prevent development of PJK/PJF. The value of VPA can be augmented through integration with GAP/SAAS frameworks to prevent complications and improve quality of life.

How Good Are Surgeons at Achieving Their Preoperative Goal Sagittal Alignment Following Adult Deformity Surgery?

STUDY DESIGN

Multicenter, prospective cohort.

OBJECTIVES

Malalignment following adult spine deformity (ASD) surgery can impact outcomes and increase mechanical complications. We assess whether preoperative goals for sagittal alignment following ASD surgery are achieved.

METHODS

ASD patients were prospectively enrolled based on 3 criteria: deformity severity (PI-LL ≥25°, TPA ≥30°, SVA ≥15 cm, TCobb≥70° or TLCobb≥50°), procedure complexity (≥12 levels fused, 3-CO or ACR) and/or age (>65 and ≥7 levels fused). The surgeon documented sagittal alignment goals prior to surgery. Goals were compared with achieved alignment on first follow-up standing radiographs.

RESULTS

The 266 enrolled patients had a mean age of 61.0 years (SD = 14.6) and 68% were women. Mean instrumented levels was 13.6 (SD = 3.8), and 23.2% had a 3-CO. Mean (SD) offsets (achieved-goal) were: SVA = -8.5 mm (45.6 mm), PI-LL = -4.6° (14.6°), TK = 7.2° (14.7°), reflecting tendencies to undercorrect SVA and PI-LL and increase TK. Goals were achieved for SVA, PI-LL, and TK in 74.4%, 71.4%, and 68.8% of patients, respectively, and was achieved for all 3 parameters in 37.2% of patients. Three factors were independently associated with achievement of all 3 alignment goals: use of PACs/equivalent for surgical planning (P < .001), lower baseline GCA (P = .009), and surgery not including a 3-CO (P = .037).

CONCLUSIONS

Surgeons failed to achieve goal alignment of each sagittal parameter in ∼25-30% of ASD patients. Goal alignment for all 3 parameters was only achieved in 37.2% of patients. Those at greatest risk were patients with more severe deformity. Advancements are needed to enable more consistent translation of preoperative alignment goals to the operating room.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

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Key Words

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

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Affiliation(s)

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

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The Effect of Age-Adjusted Sagittal Alignment on the Result of Posterior Decompression Surgery for Lumbar Spinal Canal Stenosis

STUDY DESIGN

Retrospective case series.

OBJECTIVE

The aim of this study was to compare the outcomes of posterior decompression surgery for lumbar spinal canal stenosis (LSS) in patients with preoperative sagittal malalignment (MA) with those without, after adjusting for age and sex.

SUMMARY OF BACKGROUND DATA

Sagittal balance is an important factor in spine surgery and is thought to affect postoperative outcomes after LSS. However, the relationship between sagittal MA and postoperative outcomes has not been thoroughly examined.

PATIENTS AND METHODS

We included 533 patients who underwent surgical treatment for LSS and also achieved 2-year follow-up. Patients were categorized into either an MA+ group (69 patients) or a matched-alignment (MA-) group (348 patients) based on age-adjusted preoperative sagittal alignment. We compared the baseline and 2-year postoperative health-related quality of life (HRQOL) using the Visual Analog Scale and Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) scores. We also calculated clinical efficacy using the minimal clinically important difference based on JOABPEQ scores, and age and sex-adjusted JOABPEQ scores 2 years after surgery. Differences between groups were examined using the Mann-Whitney U test and χ 2 analysis, where applicable.

RESULTS

Both groups showed an improved HRQOL after decompression surgery. Similar proportions of patients showed substantial improvement, as estimated by the minimal clinically important difference, in 4 out of 5 subdomains of the JOABPEQ. A significantly smaller proportion of patients in the MA+ group showed substantial improvement in lumbar function. The age and sex-adjusted HRQOL scores 2 years after surgery were lower in the MA+ group, particularly in the lumbar function and social life function subdomains of the JOABPEQ.

CONCLUSION

The effects of posterior decompression surgery alone can still be observed at least 2 years postoperatively for patients with LSS and concomitant sagittal MA. Patients with sagittal MA may experience lower HRQOL than those without this type of MA.

Functional Alignment Within the Fusion in Adult Spinal Deformity (ASD) Improves Outcomes and Minimizes Mechanical Failures

STUDY DESIGN

Retrospective review of an adult deformity database.

OBJECTIVE

To identify pelvic incidence (PI) and age-appropriate physical function alignment targets using a component angle of T1-pelvic angle within the fusion to define correction and their relationship to proximal junctional kyphosis (PJK) and clinical outcomes.

SUMMARY OF BACKGROUND DATA

In preoperative planning, a patient's PI is often utilized to determine the alignment target. In a trend toward more patient-specific planning, age-specific alignment has been shown to reduce the risk of mechanical failures. PI and age have not been analyzed with respect to defining a functional alignment.

METHODS

A database of patients with operative adult spinal deformity was analyzed. Patients fused to the pelvis and upper-instrumented vertebrae above T11 were included. Alignment within the fusion correlated with clinical outcomes and PI. Short form 36-Physical Component Score (SF36-PCS) normative data and PI were used to compute functional alignment for each patient. Overcorrected, under-corrected, and functionally corrected groups were determined using T10-pelvic angle (T10PA).

RESULTS

In all, 1052 patients met the inclusion criteria. T10PA correlated with SF36-PCS and PI (R=0.601). At six weeks, 40.7% were functionally corrected, 39.4% were overcorrected, and 20.9% were under-corrected. The PJK incidence rate was 13.6%. Overcorrected patients had the highest PJK rate (18.1%) compared with functionally (11.3%) and under-corrected (9.5%) patients ( P <0.05). Overcorrected patients had a trend toward more PJK revisions. All groups improved in HRQL; however, under-corrected patients had the worst 1-year SF36-PCS offset relative to normative patients of equivalent age (-8.1) versus functional (-6.1) and overcorrected (-4.5), P <0.05.

CONCLUSIONS

T10PA was used to determine functional alignment, an alignment based on PI and age-appropriate physical function. Correcting patients to functional alignment produced improvements in clinical outcomes, with the lowest rates of PJK. This patient-specific approach to spinal alignment provides adult spinal deformity correction targets that can be used intraoperatively.

The Impact of Lumbopelvic Realignment Versus Prevention Strategies at the Upper-instrumented Vertebra on the Rates of Junctional Failure Following Adult Spinal Deformity Surgery

STUDY DESIGN/SETTING

Retrospective.

OBJECTIVE

Evaluate the surgical technique that has the greatest influence on the rate of junctional failure following ASD surgery.

SUMMARY OF BACKGROUND DATA

Differing presentations of adult spinal deformity(ASD) may influence the extent of surgical intervention and the use of prophylaxis at the base or the summit of a fusion construct to influence junctional failure rates.

MATERIALS AND METHODS

ASD patients with two-year(2Y) data and at least 5-level fusion to the pelvis were included. Patients were divided based on UIV: [Longer Construct: T1-T4; Shorter Construct: T8-T12]. Parameters assessed included matching in age-adjusted PI-LL or PT, aligning in GAP-relative pelvic version or Lordosis Distribution Index. After assessing all lumbopelvic radiographic parameters, the combination of realigning the two parameters with the greatest minimizing effect of PJF constituted a good base. Good s was defined as having: (1) prophylaxis at UIV (tethers, hooks, cement), (2) no lordotic change(under-contouring) greater than 10° of the UIV, (3) preoperative UIV inclination angle<30°. Multivariable regression analysis assessed the effects of junction characteristics and radiographic correction individually and collectively on the development of PJK and PJF in differing construct lengths, adjusting for confounders.

RESULTS

In all, 261 patients were included. The cohort had lower odds of PJK(OR: 0.5,[0.2-0.9]; P =0.044) and PJF was less likely (OR: 0.1,[0.0-0.7]; P =0.014) in the presence of a good summit. Normalizing pelvic compensation had the greatest radiographic effect on preventing PJF overall (OR: 0.6,[0.3-1.0]; P =0.044). In shorter constructs, realignment had a greater effect on decreasing the odds of PJF(OR: 0.2,[0.02-0.9]; P =0.036). With longer constructs, a good summit lowered the likelihood of PJK(OR: 0.3,[0.1-0.9]; P =0.027). A good base led to zero occurrences of PJF. In patients with severe frailty/osteoporosis, a good summit lowered the incidence of PJK(OR: 0.4,[0.2-0.9]; P =0.041) and PJF (OR: 0.1,[0.01-0.99]; P =0.049).

CONCLUSION

To mitigate junctional failure, our study demonstrated the utility of individualizing surgical approaches to emphasize an optimal basal construct. Achievement of tailored goals at the cranial end of the surgical construct may be equally important, especially for higher-risk patients with longer fusions.

LEVEL OF EVIDENCE

3.

Persistent Lower Extremity Compensation for Sagittal Imbalance After Surgical Correction of Complex Adult Spinal Deformity: A Radiographic Analysis of Early Impact

BACKGROUND AND OBJECTIVES

Achieving spinopelvic realignment during adult spinal deformity (ASD) surgery does not always produce ideal outcomes. Little is known whether compensation in lower extremities (LEs) plays a role in this disassociation. The objective is to analyze lower extremity compensation after complex ASD surgery, its effect on outcomes, and whether correction can alleviate these mechanisms.

METHODS

We included patients with complex ASD with 6-week data. LE parameters were as follows: sacrofemoral angle, knee flexion angle, and ankle flexion angle. Each parameter was ranked, and upper tertile was deemed compensation. Patients compensating and not compensating postoperatively were propensity score matched for body mass index, frailty, and T1 pelvic angle. Linear regression assessed correlation between LE parameters and baseline deformity, demographics, and surgical details. Multivariate analysis controlling for baseline deformity and history of total knee/hip arthroplasty evaluated outcomes.

RESULTS

Two hundred and ten patients (age: 61.3 ± 14.1 years, body mass index: 27.4 ± 5.8 kg/m2, Charlson Comorbidity Index: 1.1 ± 1.6, 72% female, 22% previous total joint arthroplasty, 24% osteoporosis, levels fused: 13.1 ± 3.8) were included. At baseline, 59% were compensating in LE: 32% at hips, 39% knees, and 36% ankles. After correction, 61% were compensating at least one joint. Patients undercorrected postoperatively were less likely to relieve LE compensation (odds ratio: 0.2, P = .037). Patients compensating in LE were more often undercorrected in age-adjusted pelvic tilt, pelvic incidence, lumbar lordosis, and T1 pelvic angle and disproportioned in Global Alignment and Proportion (P < .05). Patients matched in sagittal age-adjusted score at 6 weeks but compensating in LE were more likely to develop proximal junctional kyphosis (odds ratio: 4.1, P = .009) and proximal junctional failure (8% vs 0%, P = .035) than those sagittal age-adjusted score-matched and not compensating in LE.

CONCLUSION

Perioperative lower extremity compensation was a product of undercorrecting complex ASD. Even in age-adjusted realignment, compensation was associated with global undercorrection and junctional failure. Consideration of lower extremities during planning is vital to avoid adverse outcomes in perioperative course after complex ASD surgery.

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.

Patient-Centered Outcomes Following Prone Lateral Single-Position Approach to Same-Day Circumferential Spine Surgery

STUDY DESIGN

Retrospective study.

OBJECTIVE

Evaluate surgical characteristics and postoperative 2-year results of the PL approach to spinal fusion.

SUMMARY OF BACKGROUND DATA

Prone-lateral(PL) single positioning has recently gained popularity in spine surgery due to lower blood loss and operative time but has yet to be examined for other notable outcomes, including realignment and patient-reported measures.

MATERIALS AND METHODS

We included circumferential spine fusion patients with a minimum one-year follow-up. Patients were stratified into groups based on undergoing PL approach versus same-day staged (Staged). Mean comparison tests identified differences in baseline parameters. Multivariable logistic regression, controlling for age, levels fused, and Charlson Comorbidity Index were used to determine the influence of the approach on complication rates, radiographic and patient-reported outcomes up to two years.

RESULTS

One hundred twenty-two patients were included of which 72(59%) were same-day staged and 50(41%) were PL. PL patients were older with lower body mass index (both P <0.05). Patients undergoing PL procedures had lower estimated blood loss and operative time (both P <0.001), along with fewer osteotomies (63% vs. 91%, P <0.001). This translated to a shorter length of stay (3.8 d vs. 4.9, P =0.041). PL procedures demonstrated better correction in both PT (4.0 vs. -0.2, P =0.033 and pelvic incidence and lumbar lordosis (-3.7 vs. 3.1, P =0.012). PL procedures were more likely to improve in GAP relative pelvic version (OR: 2.3, [1.5-8.8]; P =0.003]. PL patients suffered lesser complications during the perioperative period and greater improvement in NRS-Back (-6.0 vs. -3.3, P =0.031), with less reoperations (0.0% vs. 4.8%, P =0.040) by two years.

CONCLUSIONS

Patients undergoing PL single-position procedures received less invasive procedures with better correction of pelvic compensation, as well as earlier discharge. The prone lateral cohort also demonstrated greater clinical improvement and a lower rate of reoperations by two years following spinal corrective surgery.

LEVEL OF EVIDENCE

Level-III.

Development and Validation of an Online Calculator to Predict Proximal Junctional Kyphosis After Adult Spinal Deformity Surgery Using Machine Learning

OBJECTIVE

Although adult spinal deformity (ASD) surgery aims to restore and maintain alignment, proximal junctional kyphosis (PJK) may occur. While existing scoring systems predict PJK, they predominantly offer a generalized 3-tier risk classification, limiting their utility for nuanced treatment decisions. This study seeks to establish a personalized risk calculator for PJK, aiming to enhance treatment planning precision.

METHODS

Patient data for ASD were sourced from the Korean spinal deformity database. PJK was defined a proximal junctional angle (PJA) of ≥ 20° at the final follow-up, or an increase in PJA of ≥ 10° compared to the preoperative values. Multivariable analysis was performed to identify independent variables. Subsequently, 5 machine learning models were created to predict individualized PJK risk post-ASD surgery. The most efficacious model was deployed as an online and interactive calculator.

RESULTS

From a pool of 201 patients, 49 (24.4%) exhibited PJK during the follow-up period. Through multivariable analysis, postoperative PJA, body mass index, and deformity type emerged as independent predictors for PJK. When testing machine learning models using study results and previously reported variables as hyperparameters, the random forest model exhibited the highest accuracy, reaching 83%, with an area under the receiver operating characteristics curve of 0.76. This model has been launched as a freely accessible tool at: (https://snuspine.shinyapps.io/PJKafterASD/).

CONCLUSION

An online calculator, founded on the random forest model, has been developed to gauge the risk of PJK following ASD surgery. This may be a useful clinical tool for surgeons, allowing them to better predict PJK probabilities and refine subsequent therapeutic strategies.

PreOperative Planning for Adult Spinal Deformity Goals: Level Selection and Alignment Goals

Adult Spinal Deformity (ASD) is a complex pathologic condition with significant impact on quality of life, including pain, loss of function, and fatigue. Achieving realignment goals is crucial for long-term results. Reliable preoperative planning strategies, including nomograms, measurement tools, and level selection, are key to maximizing the likelihood of achieving a good outcome following ASD corrective surgery. This review covers recent literature on such strategies, including review of the different targets for realignment and their association with outcomes (both patients-reported outcomes and complications), selection of upper and lower instrumented vertebrae, and the latest innovation in preoperative planning for deformity surgery.

Comparative Analysis of Hounsfield Units and Vertebral Bone Quality Scores for Predicting Proximal Junctional Failure in Female Adult Spinal Deformity Patients Undergoing Planned 2-Stage Corrective Surgery with Lateral Lumbar Interbody Fusion

OBJECTIVE

This study aimed to evaluate the utility of computed tomography (CT)-based Hounsfield units (HUs) and magnetic resonance imaging-based Vertebral Bone Quality (VBQ) scores as alternatives to dual-energy x-ray absorptiometry for predicting the risk of proximal junctional failure (PJF) in female patients with adult spinal deformity (ASD) undergoing 2-stage corrective surgery with lateral lumbar interbody fusion (LLIF).

METHODS

The study included 53 female patients with ASD who underwent 2-stage corrective surgery with LLIF from January 2016 to April 2022 with a minimum follow-up of 1 year. CT and magnetic resonance imaging scans were evaluated for their correlation with PJF.

RESULTS

Of the 53 patients (mean age 70.2 years), 14 had PJF. Patients with PJF had significantly lower HU values at the upper instrumented vertebra (UIV) (113.0 ± 29.4 vs. 141.1 ± 41.5, P = 0.036) and L4 (113.4 ± 59.5 vs. 160.0 ± 64.9, P = 0.026) than those without PJF. However, there was no difference in VBQ scores between the 2 groups. PJF correlated with HU values at UIV and L4 but not with VBQ scores. Patients with PJF also had significantly different pre- and postoperative thoracic kyphosis, postoperative pelvic tilt, pelvic incidence minus lumbar lordosis, and proximal junctional angle compared to those without PJF.

CONCLUSIONS

The findings suggest that measuring HU values at UIV or L4 by CT may be useful for predicting the risk of PJF in female ASD patients undergoing 2-stage corrective surgery with LLIF. Therefore, CT-based HUs should be considered in ASD surgery planning to reduce the risk of PJF.

Proximal Junctional Kyphosis or Failure After Adult Spinal Deformity Surgery - Review of Risk Factors and Its Prevention

Proximal junction kyphosis (PJK) is a common imaging finding after long-level fusion, and proximal junctional failure (PJF) is an aggravated form of the progressive disease spectrum of PJK. This includes vertebral fracture of upper instrumented vertebra (UIV) or UIV+1, instability between UIV and UIV+1, neurological deterioration requiring surgery. Many studies have reported on PJK and PJF after long segment instrumentation for adult spinal deformity (ASD). In particular, for spine deformity surgeons, risk factors and prevention strategies of PJK and PJF are very important to minimize reoperation. Therefore, this review aims to help reduce the occurrence of PJK and PJF by updating the latest contents of PJK and PJF by 2023, focusing on the risk factors and prevention strategies of PJK and PJF. We conducted a search on multiple database for articles published until February 2023 using the search keywords "proximal junctional kyphosis," "proximal junctional failure," "proximal junctional disease," and "adult spinal deformity." Finally, 103 papers were included in this study. Numerous factors have been suggested as potential risks for the development of PJK and PJF, including a high body mass index, inadequate postoperative sagittal balance and overcorrection, advanced age, pelvic instrumentation, and osteoporosis. Recently, with the increasing elderly population, sarcopenia has been emphasized. The quality and quantity of muscle in the surgical site have been suggested as new risk factor. Therefore, spine surgeon should understand the pathophysiology of PJK and PJF, as well as individual risk factors, in order to develop appropriate prevention strategies for each patient.

Should Global Realignment Be Tailored to Frailty Status for Patients Undergoing Surgical Intervention for Adult Spinal Deformity?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Assess whether modifying spinal alignment goals to accommodate frailty considerations will decrease mechanical complications and maximize clinical outcomes.

SUMMARY OF BACKGROUND DATA

The Global Alignment and Proportion (GAP) score was developed to assist in reducing mechanical complications, but has had less success predicting such events in external validation. Higher frailty and many of its components have been linked to the development of implant failure. Therefore, modifying the GAP score with frailty may strengthen its ability to predict mechanical complications.

MATERIALS AND METHODS

We included 412 surgical ASD patients with two-year follow-up. Frailty was quantified using the modified Adult Spinal Deformity Frailty Index (mASD-FI). Outcomes: proximal junctional kyphosis and proximal junctional failure (PJF), major mechanical complications, and "Best Clinical Outcome" (BCO), defined as Oswestry Disability Index<15 and Scoliosis Research Society 22-item Questionnaire Total>4.5. Logistic regression analysis established a six-week score based on GAP score, frailty, and Oswestry Disability Index US Norms. Logistic regression followed by conditional inference tree analysis generated categorical thresholds. Multivariable logistic regression analysis controlling for confounders was used to assess the performance of the frailty-modified GAP score.

RESULTS

Baseline frailty categories: 57% not frail, 30% frail, 14% severely frail. Overall, 39 of patients developed proximal junctional kyphosis, 8% PJF, 21% mechanical complications, 22% underwent reoperation, and 15% met BCO. The mASD-FI demonstrated a correlation with developing PJF, mechanical complications, undergoing reoperation, and meeting BCO at two years (all P <0.05). Regression analysis generated the following equation: Frailty-Adjusted Realignment Score (FAR Score)=0.49×mASD-FI+0.38×GAP Score. Thresholds for the FAR score (0-13): proportioned: <3.5, moderately disproportioned: 3.5-7.5, severely disproportioned: >7.5. Multivariable logistic regression assessing FAR score demonstrated associations with mechanical complications, reoperation, and meeting BCO by two years (all P <0.05), whereas the original GAP score was only significant for reoperation.

CONCLUSION

This study demonstrated adjusting alignment goals in adult spinal deformity surgery for a patient's baseline frailty status and disability may be useful in minimizing the risk of complications and adverse events, outperforming the original GAP score in terms of prognostic capacity.

LEVEL OF EVIDENCE

III.

Proximal junctional failure in primary thoracolumbar fusion/fixation to the sacrum/pelvis for adult symptomatic lumbar scoliosis: long-term follow-up of a prospective multicenter cohort of 160 patients

OBJECTIVE

Proximal junctional failure (PJF) is a severe form of proximal junctional kyphosis. Previous reports on PJF have been limited by heterogeneous cohorts and relatively short follow-ups. The authors' objectives herein were to identify risk factors for PJF and to assess its long-term incidence and revision rates in a homogeneous cohort.

METHODS

The authors reviewed data from the Adult Symptomatic Lumbar Scoliosis 1 trial (ASLS-1), a National Institutes of Health-sponsored prospective multicenter study. Inclusion criteria were an age ≥ 40 years, ASLS (Cobb angle ≥ 30° and Oswestry Disability Index [ODI] ≥ 20 or Scoliosis Research Society revised 22-item questionnaire [SRS-22r] score ≤ 4.0 in pain, function, or self-image domains), and primary thoracolumbar fusion/fixation to the sacrum/pelvis of ≥ 7 levels. PJF was defined as a postoperative proximal junctional angle (PJA) change > 20°, fracture of the uppermost instrumented vertebra (UIV) or UIV+1 with > 20% vertebral height loss, spondylolisthesis of UIV/UIV+1 > 3 mm, or UIV screw dislodgment.

RESULTS

One hundred sixty patients (141 women) were included in this analysis and had a median age of 62 years and a mean follow-up of 4.3 years (range 0.1-6.1 years). Forty-six patients (28.8%) had PJF at a median of 0.92 years (IQR 0.14, 1.23 years) following surgery. Based on Kaplan-Meier analyses, PJF rates at 1, 2, 3, and 4 years were 14.4%, 21.9%, 25.9%, and 27.4%, respectively. On univariate analysis, PJF was associated with greater age (p = 0.0316), greater body mass index (BMI; p = 0.0319), worse baseline patient-reported outcome measures (PROMs; ODI, SRS-22r, and SF-12 Physical Component Summary [PCS]; all p < 0.04), the use of posterior column osteotomies (PCOs; p = 0.0039), and greater postoperative thoracic kyphosis (TK; p = 0.0031) and PJA (p < 0.001). The use of UIV hooks was protective against PJF (p = 0.0340). On regression analysis (without postoperative measures), PJF was associated with greater BMI (HR 1.077, 95% CI 1.007-1.153, p = 0.0317), lower preoperative PJA (HR 0.607, 95% CI 0.407-0.906, p = 0.0146), and greater preoperative TK (HR 1.362, 95% CI 1.082-1.715, p = 0.0085). Patients with PJF had worse PROMs at the last follow-up (ODI, SRS-22r subscore and self-image, and SF-12 PCS; p < 0.04). Sixteen PJF patients (34.8%) underwent revision, and PJF recurred in 3 (18.8%).

CONCLUSIONS

Among 160 primary ASLS patients with a median age of 62 years and predominant coronal deformity, the PJF rate was 28.8% at a mean 4.3-year follow-up, with a revision rate of 34.8%. On univariate analysis, PJF was associated with a greater age and BMI, worse baseline PROMs, the use of PCOs, and greater postoperative TK and PJA. The use of UIV hooks was protective against PJF. On multivariate analysis (without postoperative measures), a higher risk of PJF was associated with greater BMI and preoperative TK and lower preoperative PJA.

Influence of spinal lordosis correction location on proximal junctional failure: a biomechanical study

STUDY DESIGN

Assessment of sagittal lordosis distribution on mechanical proximal junctional failure-related risks through computer-based biomechanical models.

OBJECTIVE

To biomechanically assess how lordosis distribution influences radiographical and biomechanical indices related to Proximal Junctional Failure (PJF). The "optimal" patient-specific targets to restore the sagittal balance in posterior spinal fusion are still not known. Among these, the effect of the lumbar lordosis correction strategy on complications such as PJF remain uncertain.

METHODS

In this computational biomechanical study, five adult spinal deformity patients who underwent posterior spinal fixation were retrospectively reviewed. Their surgery, first erect posture and flexion movement were simulated with a patient-specific multibody model. Three pedicle subtraction osteotomy (PSO) levels (L3, L4, and L5) were simulated, with consistent global lordosis for a given patient and pelvic tilt adjusted accordingly to the actual surgery. Computed loads on the anterior spine and instrumentation were analyzed and compared using Kruskal-Wallis statistical tests and Spearman correlations.

RESULTS

In these models, no significant correlations were found between the lordosis distribution index (LDI), PSO level and biomechanical PJF-related indices. However, increasing the sagittal vertical axis (SVA) and thoracolumbar junction angle (TLJ) and decreasing the sacral slope (SS) increased the bending moment sustained by the rods at the proximal instrumented level (r = 0.52, 0.57, - 0.56, respectively, p < 0.05). There was a negative correlation between SS and the bending moment held by the adjacent proximal segment (r = - 0.71, p < 0.05).

CONCLUSION

Based on these biomechanical simulations, there was no correlation between the lordosis distribution and PJF-associated biomechanical factors. However, increasing SS and flattening the TLJ, as postural adjustment strategies required by a more distal PSO, did decrease such PJF-related factors. Sagittal restoration and PJF risks remain multifactorial, and the use of patient-specific biomechanical models may help to better understand the complex interrelated mechanisms.

GAP score potential in predicting post-operative spinal mechanical complications: a systematic review of the literature

PURPOSE

In 2017, the GAP score was proposed as a tool to reduce mechanical complications (MC) in adult spinal deformity (ASD) surgery: the reported MC rate for the GAP proportioned category was only 6%, which is clearly lower to the MC rate reported in the literature. The aim of this study is to analyse if the most recent literature confirms the promising results of the original article.

MATERIALS AND METHODS

Using the PRISMA flow chart, we reviewed the literature to analyse GAP score capacity in predicting MC occurrence. We included articles clearly reporting ASD surgery MC stratified by GAP categories and the score's overall capacity to predict MC using the area under the curve (AUC). The quality of the included studies was evaluated using GRADE and MINORS systems.

RESULTS

Eleven retrospective articles (1,517 patients in total) were included. The MC distribution per GAP category was as follows: GAP-P, 32.8%; GAP-MD, 42.3%; GAP-SD, 55.4%. No statistically significant difference was observed between the different categories using the Kruskal-Wallis test (p = 0.08) and the two-by-two Pearson-Chi square test (P Vs MD, p = 0.300; P Vs SD, p = 0.275; MD Vs SD, p = 0.137). The global AUC was 0.68 ± 0.2 (moderate accuracy). The included studies were of poor quality according to the GRADE system and had a high risk of bias based on the MINORS criteria.

CONCLUSION

The actual literature does not corroborate the excellent results reported by the original GAP score article. Further prospective studies, possibly stratified by type of MC and type of surgery, are necessary to validate this score.

Failure in Adult Spinal Deformity Surgery: A Comprehensive Review of Current Rates, Mechanisms, and Prevention Strategies

STUDY DESIGN

Literature review.

OBJECTIVE

The aim of this review is to summarize recent literature on adult spinal deformity (ASD) treatment failure as well as prevention strategies for these failure modes.

SUMMARY OF BACKGROUND DATA

There is substantial evidence that ASD surgery can provide significant clinical benefits to patients. The volume of ASD surgery is increasing, and significantly more complex procedures are being performed, especially in the aging population with multiple comorbidities. Although there is potential for significant improvements in pain and disability with ASD surgery, these procedures continue to be associated with major complications and even outright failure.

METHODS

A systematic search of the PubMed database was performed for articles relevant to failure after ASD surgery. Institutional review board approval was not needed.

RESULTS

Failure and the potential need for revision surgery generally fall into 1 of 4 well-defined phenotypes: clinical failure, radiographic failure, the need for reoperation, and lack of cost-effectiveness. Revision surgery rates remain relatively high, challenging the overall cost-effectiveness of these procedures.

CONCLUSION

By consolidating the key evidence regarding failure, further research and innovation may be stimulated with the goal of significantly improving the safety and cost-effectiveness of ASD surgery.

The Impact of Spinopelvic Parameters on Hip Degeneration After Spinal Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSION

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

PRESENTATION OF THE MULTICENTRIC COLLECTION SPINE SURGERY DATABASE

ABSTRACT Objectives: To present the Spine Surgery Database developed by the Brazilian Spine Study Group and the methodology involved in its creation, in addition to presenting initial informationabout the use of the database. Methods: Description of the steps for selecting the questionnaires and variables to be included in the database, initial expansion of the use of the database tophysicians close to the BSSG, a brief exploration of quality control and methods for the inclusion ofnew centers, and training on the database, in addition to a brief descriptionof some of the data included in the database. Results: Currently, the database includes 428 patients who already underwent spine surgery and 9 collection centers with at least one patient collected. Conclusion: The Brazilian Spine Study Group’s Multicentric Collection Database is a viable tool that allows patients from different sourcesto be included within a common flow. Level of Evidence V; Expert opinion.