Revision Risk After Primary Adult Spinal Deformity Surgery: A Nationwide Study With Two-Year Follow-up

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.

Iatrogenic posterior translation of the construct at the uppermost instrumented vertebrae is associated with proximal junctional kyphosis

PURPOSE

To determine if iatrogenic posterior translation (UIV SPi) at the upper instrumented vertebrae (UIV) is associated with increased mechanical complications and secondarily to generate and validate a UIV SPi threshold for increased complications.

METHODS

Two patient databases were utilized: one for generating a UIV SPi threshold and another for validation. Patients with a UIV between T8-L1 and a LIV at ilium were included. A receiver operating curve (ROC) curve analyses was performed to generate a threshold that predicted proximal junctional complications. This UIV SPi angle (-16.0°) was rounded to -15.0° for practical clinical use and validated in a separate cohort. Patients were stratified as above (most translated, MT) or below (least translated, LT) the threshold for comparative demographic and outcomes analyses.

RESULTS

Generation of the threshold on 192 patients (122 LT, 70 MT) revealed that the MT group had higher absolute postoperative UIV SVA (MT=-56.1 ± 23.1 mm vs. LT=-10.4 ± 31.8 mm, p < 0.001), higher PT (25.7° vs. 19.3°, p < 0.001), and 2.8-5.8 times greater odds of postoperative proximal junctional complications at 2-years (p < 0.05). Validation on 135 patients (95 LT, 40 MT) revealed that the MT group had 11.7 times greater odds of radiographic PJK and had 4.5 times greater odds of all-cause reoperations (p < 0.05).

CONCLUSION

Patients with UIV posterior translation, despite similar PI-LL and T1PA, exhibit a high PT and experience higher odds of proximal junctional complications. Our findings support limiting the UIV SPi to < 15° of posterior translation to mitigate postoperative mechanical complications.

LEVEL OF EVIDENCE

IV.

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 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).

Defining modern iatrogenic flatback syndrome: examination of segmental lordosis in short lumbar fusion patients undergoing thoracolumbar deformity correction

PURPOSE

Understanding the mechanism and extent of preoperative deformity in revision procedures may provide data to prevent future failures in lumbar spinal fusion patients.

METHODS

ASD patients without prior spine surgery (PRIMARY) and with prior short (SHORT) and long (LONG) fusions were included. SHORT patients were stratified into modes of failure: implant, junctional, malalignment, and neurologic. Baseline demographics, spinopelvic alignment, offset from alignment targets, and patient-reported outcome measures (PROMs) were compared across PRIMARY and SHORT cohorts. Segmental lordosis analyses, assessing under-, match, or over-correction to segmental and global lordosis targets, were performed by SRS-Schwab coronal curve type and construct length.

RESULTS

Among 785 patients, 430 (55%) were PRIMARY and 355 (45%) were revisions. Revision procedures included 181 (23%) LONG and 174 (22%) SHORT corrections. SHORT modes of failure included 27% implant, 40% junctional, 73% malalignment, and/or 28% neurologic. SHORT patients were older, frailer, and had worse baseline deformity (PT, PI-LL, SVA) and PROMs (NRS, ODI, VR-12, SRS-22) compared to primary patients (p < 0.001). Segmental lordosis analysis identified 93%, 88%, and 62% undercorrected patients at LL, L1-L4, and L4-S1, respectively. SHORT patients more often underwent 3-column osteotomies (30% vs. 12%, p < 0.001) and had higher ISSG Surgical Invasiveness Score (87.8 vs. 78.3, p = 0.006).

CONCLUSIONS

Nearly half of adult spinal deformity surgeries were revision fusions. Revision short fusions were associated with sagittal malalignment, often due to undercorrection of segmental lordosis goals, and frequently required more invasive procedures. Further initiatives to optimize alignment in lumbar fusions are needed to avoid costly and invasive deformity corrections.

LEVEL OF EVIDENCE

IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

A Sodium Oxychlorosene-Based Infection Prevention Protocol Safely Decreases Postoperative Wound Infections in Adult Spinal Deformity Surgery

INTRODUCTION

This study sought to determine the efficacy of a complex multi-institutional sodium oxychlorosene-based infection protocol for decreasing the rate of surgical site infection after instrumented spinal surgery for adult spinal deformity (ASD). Infection prevention protocols have not been previously studied in ASD patients.

METHODS

A retrospective analysis was performed of patients who underwent posterior instrumented spinal fusion of the thoracic or lumbar spine for deformity correction between January 1, 2011, and May 31, 2019. The efficacy of a multi-modal infection prevention protocol was examined. The infection prevention bundle consisted of methicillin-resistant Staphylococcus aureus testing, chlorhexidine gluconate bathing preoperatively, sodium oxychlorosene rinse, vancomycin powder placement, and surgical drain placement at the time of surgery.

RESULTS

About 254 patients fit the inclusion criteria. Among these patients, nine (3.5%) experienced post-surgical deep-wound infection. Demographics and surgical characteristics amongst infected and non-infected cohorts were similar, although diabetes trended towards being more prevalent in patients who developed a postoperative wound infection (p=0.07). Among 222 patients (87.4%) who achieved a minimum of two years of follow-ups, 184 patients (82.9%) experienced successful fusion, comparing favorably with pseudarthrosis rates in the ASD literature. Rates of pseudarthrosis and proximal junction kyphosis were similar amongst infected and non-infected patients.

CONCLUSION

An intraoperative comprehensive sodium oxychlorosene-based infection prevention protocol helped to provide a low rate of infection after major deformity correction without negatively impacting other postoperative procedure-related metrics.

Predicting major complications and discharge disposition after adult spinal deformity surgery

BACKGROUND CONTEXT

Several spine-specific comorbidity indices are available to help risk-stratify patients before they undergo invasive spine procedures. Studies of patients with adult spinal deformity (ASD) typically use the Charlson Comorbidity Index (CCI), which is not specific to spine patients.

PURPOSE

To compare the CCI with the Seattle Spine Score (SSS), the Adult Spinal Deformity-Comorbidity Score (ASD-CS), and the Modified 5-Item Frailty Index (mFI-5) and identify which tool more accurately predicted major perioperative complications and discharge disposition after ASD surgery.

STUDY DESIGN/SETTING

Retrospective review.

PATIENT SAMPLE

Patients with ASD who underwent spinal arthrodesis of at least four levels at a single institution.

OUTCOME MEASURES

Self-reported measures include SSS, ASD-CS, and mFI-5. Functional measures include the CCI.

METHODS

We retrospectively reviewed records of 164 patients with ASD who underwent spinal arthrodesis of ≥ four levels from January 2008 to February 2018 at our U.S. academic tertiary care center and who had available Oswestry Disability Index values. To assess the predictive ability of the comorbidity indices, we created five multivariable logistic regression models, with the presence of major complications and discharge disposition (home or inpatient rehabilitation) as the primary outcome variables. The base model used validated demographic and surgical factors that were predictors of complications and outcomes in those with ASD and within the broader spinal literature. The other four models used the base model along with one of the four indices. The predictive ability of each model was compared using goodness-of-fit testing, with higher pseudo-R2 values and lower Akaike information criteria (AIC) values indicating better model fit.

RESULTS

Thirty-one patients (19%) experienced major perioperative complications, and 68 (42%) were discharged to inpatient rehabilitation facilities (vs home). The model using the SSS had the highest pseudo-R2 value and lowest AIC value for both major complications and discharge disposition. The mFI-5 had a similar predictive ability. The models using the CCI and ASD-CS were weaker predictors.

CONCLUSIONS

Compared with the CCI and the ASD-CS, the SSS and the mFI-5 were strong predictors of major complications and discharge disposition after ASD surgery. These results suggest that the SSS and the mFI-5 are preferable to the CCI for clinical risk stratification and outcomes research in patients undergoing ASD surgery.

Restoration of the sagittal profile according to the Roussouly classification reduces mechanical complications and revision surgery in older patients undergoing surgery for adult spinal deformity (ASD)

PURPOSE

The mechanical complications related to ASD remain a concern due to their morbidity and associated revision surgery. Restoration of each patient's Roussouly profile may reduce these. Our aim was to examine if the restoration of the Roussouly profile reduced these complications and revision rates in older patients operated for degenerative ASD.

METHODS

Retrospective analysis of a single-centre, 2-year minimum follow-up patient database. All patients undergoing corrective surgery (≥ 4 levels) for ASD were included with analysis of demographic data, operative records, restoration of Roussouly sagittal profile, mechanical complications and revision rates. Univariate and multivariate analysis was conducted.

RESULTS

Fifty-two patients were included (mean age was 72.3 years, average follow-up 56.3 months). Twenty-six patients had a "restored" profile (50%) and 26 an "unrestored" profile (50%). The incidence of mechanical complications was 7 (27%) and 23 (88%) for the restored and unrestored groups, respectively (p < 0.001). Revision rates were 4 (15.4%) and 18 (69.2%), respectively (p < 0.000), in the restored and unrestored profiles. Univariate analysis determined that profile restoration and BMI were associated with mechanical complications and revision surgery, whilst only the profile restoration status maintained its statistical power in multivariate analysis (p = 0.002 and p = 0.002, respectively). Age was not a significant factor in univariate analysis. The relative risk for mechanical failure and revision surgery was 5.6 times (CI 1.929-16.39) and 3.08 times (CI 1.642-5.734) greater if the profile was not restored.

CONCLUSIONS

Achieving each patient's ideal Roussouly profile is associated with a reduced incidence of mechanical complications and revision rates in the older population after surgery for degenerative ASD.

Does the interfacing angle between pedicle screws and support rods affect clinical outcomes after posterior thoracolumbar fusion? A retrospective clinical study

BACKGROUND CONTEXT

Proper alignment and tightening of the pedicle screw/rod assembly after instrumented posterior fusion of the lower spine is known to be crucial in order to achieve satisfactory clinical results. Such interfacing angle mismatches indicate stress overloading of the implant system.

PURPOSE

The objective of this study is to investigate the incidence of postoperative screw/rod interfacing angle mismatch and to analyze the impact of mismatches on clinical outcome in terms of (1) revision surgery, (2) adjacent segment degeneration (ASD), and (3) pain.

STUDY DESIGN

This is a monocentric retrospective observational study.

PATIENT SAMPLE

Patients underwent fusion surgery with pedicle screw/rod systems for predominantly degenerative pathologies.

OUTCOME MEASURES

Pedicle screw/rod interfacing angle mismatch (mismatch is the angular deviation from 90° formed by the rod axis and the pedicle screw head axis as an indicator for missing form-fit) revision rate, ASD at the immediately adjacent cranial segment and VAS pain.

METHODS

Revision refers to subsequent procedures in which all or part of the original implant configuration is changed or removed. Radiographic parameters are evaluated using a/p and lateral radiographs at final follow-up. The interfacing angle mismatch between pedicle screw and rod is measured as the angle between two parallel lines on either side of each pedicle screw head and a line laterally along the associated rod. Multiple comparisons are counteracted by Bonferroni correction, adjusted significance level is at *p<.01.

RESULTS

Pedicle screw and rod interfacing angle mismatch was found in 171/406 (42.1%) of patients undergoing fusion surgery, affecting 613/3016 (20.3%) screws. The overall revision incidence was 11.8% (48/406), and a new ASD occurred in 12.1% of all patients (49/406) with an average follow-up of 5 years. Mean VAS pain score at final follow-up was 2.0. Comparison of the two groups with and without mismatches revealed statistically significantly higher (1) numbers of revision procedures performed (26.9% vs 0.9%), (2) numbers of new ASD developed (27.5% vs 3.8%), and (3) higher VAS pain scores (2.8/10 vs 1.4/10) for cases with mismatch. When comparing patients who underwent intraoperative correction and/or reduction with those who did not, statistically significant more screw mismatches (63.4% vs 39.7%) and revision surgeries (29.3% vs 9.9%) were noted in patients who had these forceful maneuvers.

CONCLUSIONS

Pedicle screw/rod interfacing angle mismatch is a frequent occurrence after fusion surgery. Mismatches indicate that the construct was assembled under mechanical stress. All preventable mechanical stresses, for example, unintentional uncontrolled forces on the instrumentation, should be avoided as much as possible, as they can negatively influence the clinical outcome.

Augmented Reality-Supported Rod Bending in Multilevel Spinal Fusion Using the ADVISE Software

BACKGROUND

One of the most common reasons for poor patient outcomes and revision surgery in spinal fusion is hardware failure. Screw loosening or pullout occurs in up to one-quarter of all cases. It is known that even small screw-rod misalignments can cause significant mechanical overloads during rod fixation, which can result in hardware failure. To address this crucial surgical step, a novel augmented reality-assisted software was developed to generate custom rod templates that are precisely adapted to the individual patient.

METHODS

The novel software, which runs on a tablet, is used in spinal fusion surgery and is based on the use of a specific pedicle screw system, in which the polyaxial screw heads are connected to detachable guides. These guides can be recognized by the tablet camera and a light detection and ranging scanner. This image information is processed to determine the spatial positions of the screw heads and to calculate an ideally fitting rod template.

RESULTS

The calculated rod template is displayed in a 1-to-1 scale on the tablet screen. This template is used to cut and bend the rods of the pedicle screw system. Finally, the custom bent rod can be inserted into the screw heads without tension.

CONCLUSIONS

The augmented reality-assisted software is intended to give surgeons access to patient-specific intraoperative real-time data, helping them in bending rods that are more precisely adapted to the individual patient compared with the freehand technique.

Readmission and Associated Factors in Surgical Versus Non-Surgical Management of Spinal Epidural Abscess: A Nationwide Readmissions Database Analysis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Spinal epidural abscess (SEA) is a rare but potentially life-threatening infection treated with antimicrobials and, in most cases, immediate surgical decompression. Previous studies comparing medical and surgical management of SEA are low powered and limited to a single institution. As such, the present study compares readmission in surgical and non-surgical management using a large national dataset.

METHODS

We identified all hospital admissions for SEA using the Nationwide Readmissions Database (NRD), which is the largest collection of hospital admissions data. Patients were grouped into surgically and non-surgically managed cohorts using ICD-10 coding and compared using information retrieved from the NRD such as demographics, comorbidities, length of stay and cost of admission.

RESULTS

We identified 350 surgically managed and 350 non-surgically managed patients. The 90-day readmission rates for surgical and non-surgical management were 26.0% and 35.1%, respectively (P < .05). Expectedly, surgical management was associated with a significantly higher charge and length of stay at index hospital admission. Surgically managed patients had a significantly lower risk of readmission for osteomyelitis (P < .05). Finally, in patients with a low comorbidity burden, we observed a significantly lower 90-day readmission rate for surgically managed patients (surgical: 23.0%, non-surgical: 33.8%, P < .05).

CONCLUSION

In patients with a low comorbidity burden, we observed a significantly lower readmission rate for surgically managed patients than non-surgically managed patients. The results of this study suggest a lower readmission rate as an advantage to surgical management of SEA and emphasize the importance of SEA as a not-to-miss diagnosis.

Demineralized cortical fibers are associated with a low pseudarthrosis rate in patients undergoing surgery for adult spinal deformity without three-column osteotomy

Introduction

Following surgical treatment for adult spinal deformity (ASD) there is an increased risk of revision surgery due to mechanical failure or pseudarthrosis. Demineralized cortical fibers (DCF) were introduced at our institution aiming to reduce the risk of pseudarthrosis after ASD surgery.

Research question

We wanted to investigate the effect of DCF on postoperative pseudarthrosis compared with allogenic bone graft in ASD surgery without three-column osteotomies (3CO).

Materials & Methods

All patients undergoing ASD surgery between January 1, 2010 to June 31, 2020 were included in this interventional study with historical controls. Patients with current or previous 3CO were excluded. Before February 1, 2017, patients undergoing surgery received auto- and allogenic bone graft (non-DCF group) whilst patients after received DCF in addition to autologous bone graft (DCF group). Patients were followed for at least two years. The primary outcome was radiographic or CT-verified postoperative pseudarthrosis requiring revision surgery.

Results

We included 50 patients in the DCF group and 85 patients in the non-DCF group for final analysis. Pseudarthrosis requiring revision surgery at two-year follow-up occurred in seven (14%) patients in the DCF group compared with 28 (33%) patients in the non-DCF group (p ​= ​0.016). The difference was statistically significant, corresponding to a relative risk of 0.43 (95%CI: 0.21-0.94) in favor of the DCF group.

Conclusion

We assessed the use of DCF in patients undergoing ASD surgery without 3CO. Our results suggest that the use of DCF was associated with a considerable decreased risk of postoperative pseudarthrosis requiring revision surgery.

The dynamic sagittal balance: Definition of dynamic spino-pelvic parameters using a method based on gait analysis

Introduction

Evaluation of sagittal balance parameters is a standard assessment before spine surgery. However, these parameters can change during walking. We aimed to describe the behavior of spino-pelvic parameters during walking in healthy subjects.

Material and methods

Analyses were performed in 60 healthy subjects. Static spinal sagittal balance parameters were assessed. We performed gait analysis and we used SMART-DX 500® to analyze parameters aimed at defining dynamic sagittal balance, including pelvic tilt angle (PTA), sagittal trunk shift (STS), and trunk angle (TA). We considered rotational and obliquity movements of the pelvis, flexo-extension movements of the hip, trunk, and knees. Analyses were performed in a standing posture and during walking.

Results

PTA-cycle, PTA-stance, PTA-swing, STS-cycle, STS-stance, and STS-swing showed good-to-excellent internal reliability (ICC = 0.867; ICC = 0.700; ICC = 0.817, respectively). The parameters with the lowest variability were radiographic PI (CV = 16.53%), PTA-stance (CV = 9.55%), and PTA-swing (CV = 17.22%). PT was directly related to PTA-cycle (r = 0.534, p = .027). PI was inversely correlated with trunk flexo-extension range of motion (r = -0.654, p = .004) and dynamic PT (r = -0.489, p = .047). LL and SS were directly related to knee flexo-extension (r = 0.505, p = .039; r = 0.493, p = .045, respectively). SVA was correlated with the trunk obliquity in dynamics (r = 0.529, p = .029). PTA-cycle was directly related to trunk obliquity (r = 0.538, p = .049). STS and TA in the three phases of step were related to the kinematic parameters of the pelvis. TA was related to flexo-extension of the hip and knee.

Conclusions

Variations of dynamic spino-pelvic parameters occur during walking and modify sagittal balance from a static to a dynamic condition.

Degenerative Spine Surgery in Patients with Parkinson Disease: A Systematic Review

BACKGROUND

Parkinson disease (PD) has been recognized as responsible for concurrent spinal disorders. Surgical correction may be necessary, but the complexity of such fragile patients may require specific considerations. We systematically reviewed the literature on degenerative spine surgery in patients with PD.

METHODS

PubMed, Scopus, Web of Science, and Cochrane were searched according to the PRISMA guidelines to include studies reporting clinical data of patients with PD undergoing degenerative spine surgery. Clinical characteristics, treatment protocols, and outcomes were analyzed.

RESULTS

We included 22 articles comprising 442 patients (61.5% female). Mean age was 66.9 ± 3.5 years (range, 41-83 years). Mean PD duration and modified Hoehn and Yahr stage were 4.46 ± 2.39 years and 2.3 ± 0.8, respectively. Operation types included fusion (55.3%) and decompression (41.6%). Mean operated spine levels were 6.0 ± 5.08. A total of 377 postoperative complications occurred in 34.6% patients, categorized into mechanical failure (58.0%), infection (15.1%), or neurologic (10.7%). Of patients, 31.8% required surgical revisions, with an average of 1.88 ± 1.03 revisions per patient. The average normalized presurgery, postsurgery, and final aggregate numeric patient outcome scores were 0.37 ± 0.13, 0.63 ± 0.18, and 0.61 ± 0.19, respectively, with a score of 0 and 1 representing the worst and best possible score.

CONCLUSIONS

Degenerative spine surgery in patients with PD is challenging, with complications and revisions occurring in up to a third of treated patients. Surgery should be offered when other treatment options have proved ineffective and is typically reserved for patients with myelopathy or significant disability. Successful outcomes depend on strong interdisciplinary support to control the movement disorder before and after surgery.

Surgical site infection is a major risk factor of pseudarthrosis in adult spinal deformity surgery

BACKGROUND CONTEXT

Despite the evidence in appendicular skeletal surgery, the effect of infection on spinal fusion remains unclear, particularly after Adult Spinal Deformity (ASD) surgery.

PURPOSE

The purpose of this study was to determine the impact of surgical site infection (SSI) in ASD surgery fusion rates and its association with other risks factors of pseudarthrosis.

STUDY DESIGN

We conducted an international multicenter retrospective study on a prospective cohort of patients operated for spinal deformity.

PATIENT SAMPLE

A total of 956 patients were included (762 females and 194 males).

OUTCOME MEASURES

Patient's preoperative characteristics, pre and postoperative spinopelvic parameters, surgical variables, postoperative complications and were recorded. Surgical site infections were asserted in case of clinical signs associated with positive surgical samples. Each case was treated with surgical reintervention for debridement and irrigation. Presence of pseudarthrosis was defined by the association of clinical symptoms and radiological signs of nonfusion (either direct evidence on CT-scan or indirect radiographic clues such as screw loosening, rod breakage, screw pull out or loss of correction). Each iterative surgical intervention was collected.

METHODS

Univariate and multivariate analysis with logistic regression models were performed to evaluate the role of risk factors of pseudarthrosis.

RESULTS

Nine hundred fifty-six surgical ASD patients with more than two years of follow-up were included in the study. 65 of these patients were treated for SSI (6.8%), 138 for pseudarthrosis (14.4%), and 28 patients for both SSI and pseudarthrosis. On multivariate analysis, SSI was found to be a major risk factor of pseudarthrosis (OR=4.4; 95% CI=2.4,7.9) as well as other known risks factors: BMI (OR=1.1; 95% CI=1.0,1.1), smoking (OR=1.6; 95% CI=1.1,2.9), performance of Smith-Petersen osteotomy (OR = 1.6; 95% CI 1.0,2.6), number of vertebrae instrumented (OR=1.1; 95% CI=1.1,1.2) and the caudal level of fusion, with a distal exponential increment of the risk (OR max for S1=6, 95% CI=1.9,18.6).

CONCLUSION

SSI significantly increases the risk of pseudarthrosis with an OR of 4.4.

Sectional Correction Technique in Dystrophic Scoliosis Secondary to Neurofibromatosis Type 1: A Comparison with Traditional 2-Rod Correction Technique

OBJECTIVE

The purpose of this study was to compare the traditional 2-rod correction technique with the sectional correction technique in terms of radiographic results and clinical outcomes for patients with dystrophic scoliosis caused by neurofibromatosis type 1 (NF1).

METHODS

From May 2015 to April 2018, 53 patients with dystrophic scoliosis caused by NF1 underwent 1-stage posterior corrective surgery. Patients were separated into 2 groups based on technique: the sectional correction technique (SC group) and the traditional 2-rod technique (TT group). Before surgery and at the final follow-up, the demographic information, radiographic parameters, and clinical outcomes were compared between the groups using independent-sample t tests.

RESULTS

The SC group consisted of 24 patients, while the TT group consisted of 29 patients. Patients in the SC group showed a higher coronal balance distance after the operation (8.3 ± 8.2 mm vs. 16.2 ± 8.8 mm, P = 0.002) and at the final follow-up (9.5 ± 9.3 mm vs. 19.3 ± 10.1 mm, P < 0.0001). At the last follow-up, the loss of correction in the SC group was 2.2 ± 0.9 and 2.1 ± 0.7 in the coronal and sagittal planes, respectively, and these values were significantly lower than those in the TT group (5.3 ± 1.6 in the coronal plane and 4.5 ± 1.9 in the sagittal plane, both P < 0.05). The SC group had better improvement based on appearance and satisfaction score at the final follow-up.

CONCLUSIONS

The sectional correction technique using a concave domino connector can restore coronal imbalance and reduce the risk of implant failure.

Complications in the Elderly Population Undergoing Spinal Deformity Surgery: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVES

The elderly have an increased risk of perioperative complications for Adult Spinal Deformity (ASD) corrections. Stratification of these perioperative complications based on risk type and specific risk factors, however, remain unclear. This paper will systematically review perioperative risk factors in the elderly undergoing ASD correction stratified by type: medical, implant-related, proximal junctional kyphosis (PJK), and need for revision surgery.

METHODS

A systematic review was performed using the PRISMA guidelines. A query of PubMed was performed to identify publications pertinent to ASD in the elderly. Publications included in this review focused on patients ≥65 years old who underwent operative management for ASD to assess for risk factors of perioperative complications.

RESULTS

A total of 734 unique citations were screened resulting in ten included articles for this review. Pooled incidence of perioperative complications included medical complications (21%), implant-related complications (16%), PJK (29%), and revision surgery (13%). Meta-analysis calculated greater preoperative PT (WMD 2.66; 95% Cl .36-4.96; P = .02), greater preoperative SVA (WMD 2.24; 95% Cl .62-3.86; P = .01), and greater postoperative SVA (WMD .97; 95% Cl .03-1.90; P = .04) to significantly correlate with development of PJK with no evidence of publication bias or concerns in study heterogeneity.

CONCLUSIONS

There is a paucity of literature describing perioperative complications in the elderly following ASD surgery. Appropriate understanding of modifiable risk factors for the development of medical and implant-related complications, proximal junctional kyphosis, and revision surgeries presents an opportunity to decrease morbidity and improve patient outcomes.

Is preoperative S-albumin associated to postoperative complications and readmission in patients with adult spinal deformity: a prospective analysis of 128 patients using the Spine AdVerse Event Severity (SAVES) system

PURPOSE

To assess the association between preoperative S-albumin and postoperative outcome following adult spinal deformity (ASD) surgery.

METHODS

All patients undergoing ASD surgery from February 1, 2017 and January 31, 2018 at a single quaternary referral center were prospectively included. Adverse events (AE) during admission were assessed using the Spine AdVerse Events Severity (SAVES) system. Based on preoperative S-albumin, patients were categorized as "normal" or "abnormal" and compared regarding postoperative outcome, adverse events (AEs), 30- and 90-day readmission, revision surgery, and mortality.

RESULTS

A total of 128 patients aged ≥ 18 years were included, and S-albumin was available in 88%. Of these, 73% (n = 93) were classified as "normal", 16% (n = 20) as "abnormal", and 12% (n = 15) as "missing". The "normal" albumin group had less comorbidity burden [ASA score 2 (2, 3) vs 3 (2, 3), p = 0.011], higher hemoglobin levels (8.4 (± 0.9) mmol/L vs 7.4 (± 1.1) mmol/L, p < 0.001), and higher S-albumin (38.9 (± 2.7) g/L vs 31.9 (± 4.4) g/L, < 0.001). The rate of 90-day readmission was significantly increased in the "abnormal" group (65% vs 36%), corresponding to a relative risk increase of 1.25 (95% CI 1.02-1.52, p = 0.029). Similar increased risks were found in subsequent logistic regression analyses, although results were not significant in multivariable analysis (p = 0.102). Comparing remaining outcome parameters, point estimates revealed increased AEs, 30-day readmission, and revision in the "abnormal" albumin group, although effects did not reach statistical significance.

CONCLUSIONS

In a prospective, consecutive, single-center cohort of 128 patients undergoing ASD surgery, we found a significant association between "abnormal" preoperative S-albumin and increased 90-day readmission. Furthermore, although the findings were not statistically significant, we did find that AEs, 30-day readmission, and revision were numerically more frequent in the "abnormal" group, suggesting an expected tendency that should be further investigated. We conclude that nutritional status prior to ASD surgery could be important to consider and suggest validation in larger prospective cohorts.

LEVEL OF EVIDENCE

Prognostic II.

Risk Factors for Revision Surgery After Primary Adult Thoracolumbar Deformity Surgery

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

The aim was to identify the risk factors for revision surgery within 2 years of patients undergoing primary adult spinal deformity (ASD) surgery.

SUMMARY OF BACKGROUND DATA

Previous literature reports estimate 20% of patients undergoing thoracolumbar ASD correction undergo reoperation within 2 years. There is limited published data regarding specific risk factors for reoperation in ASD surgery in the short term and long term.

METHODS

The authors queried the MarketScan database in order to identify patients who were diagnosed with a spinal deformity and underwent ASD surgery from 2007 to 2015. Patient-level factors and revision risk were investigated during 2 years after primary ASD surgery. Patients under the age of 18 years and those with any prior history of trauma or tumor were excluded from this study.

RESULTS

A total 7422 patients underwent ASD surgery during 2007-2015 in the data set. Revision rates were 13.1% at 90 days, 14.5% at 6 months, 16.7% at 1 year, and 19.3% at 2 years. In multivariate multiple logistic regression analysis, obesity [adjusted odds ratio (OR): 1.58, P<0.001] and tobacco use (adjusted OR: 1.38, P=0.0011) were associated with increased odds of reoperation within 2 years. Patients with a combined anterior-posterior approach had lower odds of reoperation compared with those with posterior only approach (adjusted OR: 0.66, P=0.0117).

CONCLUSIONS

Obesity and tobacco are associated with increased odds of revision surgery within 2 years of index ASD surgery. Male sex and combined surgical approach are associated with decreased odds of revision surgery.

Sequential correction technique in degenerative scoliosis with type C coronal imbalance: a comparison with traditional 2-rod technique

OBJECTIVE

The aim of this study was to compare the radiographic and clinical outcomes in patients with degenerative scoliosis (DS) with type C coronal imbalance who underwent either a sequential correction technique or a traditional 2-rod technique with a minimum of 2 years of follow-up.

METHODS

DS patients with type C coronal imbalance undergoing posterior correction surgery from February 2014 to January 2018 were divided into groups by technique: the sequential correction technique (SC group) and the traditional 2-rod technique (TT group). Radiographic parameters, including Cobb angle, coronal balance distance (CBD), global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope, were assessed pre- and postoperatively. The SF-36 questionnaire was used to assess quality of life.

RESULTS

A total of 34 patients were included. Significant postoperative improvement in the Cobb angle of the main curve, CBD, GK, TK, LL, SVA, and PT was found in both groups (p < 0.05). Postoperatively, the coronal balance was type A in 13 patients (92.9%) in the SC group and in 16 patients (80.0%) in the TT group (p = 0.298). In the TT group, 1 patient had deteriorative coronal imbalance immediately postoperatively, and coronal imbalance deteriorated from type A to type C in 2 patients during follow-up. The scores of Physical Functioning, Role-Physical, Bodily Pain, Vitality, Social Functioning, Role-Emotional, and Mental Health were statistically improved postoperatively (p < 0.05) in both groups. Type C coronal imbalance at the last follow-up was associated with a relatively worse quality of life. There were no implant failures during follow-up in the SC group, whereas rod fracture was observed in 3 patients in the TT group.

CONCLUSIONS

Compared with the traditional 2-rod technique, the sequential correction technique can simplify rod installation procedure, enhance internal instrumentation, and reduce risk of implant failures. The sequential correction technique could be routinely recommended for DS patients with type C coronal imbalance.

Evaluation of the reduction, tightening and gripping performance of an innovative set screw technology for instrumented posterior lumbar fusion: A biomechanical study

BACKGROUND

Instrumented posterior lumbar fusion with top-loading pedicle screw systems (PSS) requires fully tightened set screws to achieve a secure fixation and symmetric load condition. This assumes a complete reduction of the rod by 90°, which is not always attainable in situ, especially under constraint. The objective of this work is to compare the mechanical performance of different innovative set screw technologies, which should improve the tightening process.

HYPOTHESIS

The hypotheses of the study are that modifications to the screw and screwdriver unit can (1) improve the quality of set screw tightening and (2) increase the axial gripping capacity of the construct.

MATERIALS AND METHODS

The four set screw technologies under investigation include a standard set screw with a flat surface (F-S; control group), a set screw with a convex surface (C-S) and a shaft tip method screwdriver used in combination with both flat (F-STM) and convex set screws (C-STM). The quality of set screw tightening is categorized as follows: failed=the rod is not completely reduced; reduced=the rod is successfully reduced but the set screw is not correctly fixed; good=remaining cases. An axial gripping capacity test is performed by a universal testing machine (Instron®) with a force capacity of 5kN.

RESULTS

Regarding the quality of set screw tightening, comparisons between F-S vs. F-STM, F-S vs. C-STM and between C-S vs. C-STM show statistically significant differences (p<0.001). The axial gripping capacity test shows mean gripping forces of 1223N (STD 331) in the F-STM group and of 1724N (STD 168) in the C-STM group with statistically significant differences between both groups (p=0.003).

DISCUSSION

Several biomechanical and clinical case studies have identified possible effects of misaligned rod-screw interfaces such as screw pull-out during rod reduction, screw loosening, screw or rod breakage, misalignment, adjacent segment degeneration and worsening of the clinical outcome. C-STM-technology thus supports controlled fixation in the sense of applying appropriate forces for correction or fixation during PSS assembly as well as friction-reduced final alignment and tightening with the aim to reduce implant loosening, hardware failure and reoperations, while respecting anatomical and biomechanical balance.

Importance of achieving Scoliosis Research Society-22r minimal clinically important difference for improving patient satisfaction after adult spinal deformity surgery

OBJECTIVE

Achievement of minimal clinically important differences (MCIDs) in the Scoliosis Research Society-22r (SRS-22r) subdomains represents surgical efficacy. However, whether achievements of MCIDs in SRS-22r domains are associated with long-term satisfaction in patients with adult spinal deformity (ASD) is unclear. This study aimed to elucidate factors affecting patient satisfaction after thoracopelvic corrective fusion surgery in patients with ASD.

METHODS

Data obtained in 187 patients with ASD who underwent extensive corrective fusion surgery from the thoracic spine to the pelvis between 2010 and 2017 and underwent follow-up for 2 years were retrospectively reviewed. The authors investigated the likelihood of achieving MCIDs in the function, pain, self-image, mental health, and subtotal domains 2 years after surgery. The following MCID values were used: function, 0.90; pain, 0.85; self-image, 1.05; mental health, 0.70; and subtotal, 1.05. Multivariate analysis was performed to evaluate factors associated with patient satisfaction 2 years after surgery.

RESULTS

The average satisfaction scores in the group that achieved MCID and the group that did not were as follows: 3.97 and 3.37 for function (p < 0.001), 3.66 and 3.51 for pain (p = 0.221), 3.84 and 3.06 for self-image (p < 0.001), 3.82 and 3.28 for mental health (p < 0.001), and 3.96 and 3.30 for subtotal (p < 0.001), respectively. Except for the pain domain, the group that achieved MCIDs showed greater satisfaction than the group that did not achieve MCIDs. On multivariate analysis, factors related to postoperative satisfaction were achievement of SRS-22r self-image (standardization coefficient 0.322, p < 0.001) and function (standardization coefficient 0.179, p = 0.026) MCIDs. Perioperative complications and revision surgery were not related to patient satisfaction.

CONCLUSIONS

Multivariate analysis demonstrated that achievement of MCIDs in SRS-22r self-image and function domains was significantly associated with postoperative satisfaction. Given that patients with poor preoperative health-related quality of life are more likely to achieve MCIDs in SRS-22r domains, surgeons should carefully consider whether to operate on patients with relatively good baseline health-related quality of life when making surgical decisions.

Predicting Reciprocal Thoracic Change, Proximal Junctional Kyphosis, and Revision Surgery in Adult Spinal Deformity

BACKGROUND

Compensatory mechanisms in patients with adult spinal deformity (ASD) that lead to poor quality of life include positive sagittal balance and pelvic retroversion. The objective of this retrospective review was to identify demographic and radiographic parameters of sagittal alignment that are correlated with thoracic kyphosis (TK), PJK, and reoperation in patients undergoing surgical correction for ASD.

METHODS

A single-center database of 155 patients with ASD undergoing surgery from 2008 to 2015 was reviewed. Patients >18 years old who underwent multilevel thoracolumbar fusion or fusion of thoracic vertebrae to the pelvis were included. Demographics and radiographic measurements of sagittal alignment were collected preoperatively, 6 weeks postoperatively, and 1 year postoperatively. Statistical analysis was performed to compare groups that did or did not develop change in thoracic kyphosis or PJK at early or late follow-up. Additionally, patients requiring reoperation were evaluated.

RESULTS

Increased thoracic kyphosis was associated with older age, hypolordosis, and comorbid PJK. Early PJK was associated with older age, hypolordosis, and increased T1 pelvic angle. Reoperation was associated with older age, higher positive sagittal balance, hypolordosis, and pelvic retroversion; PJK and thoracic kyphosis did not increase risk for reoperation.

CONCLUSIONS

Thoracic reciprocal change following surgical correction of ASD is highly associated with PJK, although neither increased risk of reoperation. PJK may be predicted by older age, hypolordosis, and increased T1 pelvic angle. Reoperation in patients with ASD is more likely in older patients with positive sagittal balance, a compensatory flat lower back, and compensatory pelvic retroversion.

Factors Associated with Improved Quality of Life Outcomes in Patients Undergoing Surgery for Adult Spinal Deformity

STUDY DESIGN

Retrospective longitudinal cohort study.

OBJECTIVE

This study aimed to elucidate factors affecting the likelihood of achieving minimum clinically important difference (MCID) to patient-reported outcomes defined by the Scoliosis Research Society-22r (SRS-22r) among patients with adult spinal deformity (ASD) who underwent extensive corrective fusion surgery from the thoracic spine to the pelvis.

SUMMARY OF BACKGROUND DATA

Achieving MCID for SRS-22r parameters was a measure of surgical efficacy. Patient characteristics and surgical and radiographic factors that affect the likelihood of achieving MCID for SRS-22r parameters are unknown.

METHODS

Data from patients with ASD who underwent extensive corrective fusion surgery from the thoracic spine to the pelvis during 2010 to 2016 were retrospectively reviewed. Data from a total of 167 patients with ≥2 years of follow-up were included. Multivariate analysis was used to investigate factors associated with the likelihood of achieving MCID for each of the SRS-22r domains (Function, Pain, Subtotal) 2 years after surgery. The following MCID values were used: 0.90 for Function, 0.85 for Pain, and 1.05 for the Subtotal.

RESULTS

MCID achievement rate was 36.5% for Function, 46.1% for Pain, and 44.3% for the Subtotal domain. In multivariate analysis, preoperative SRS-22r Function (odds ratio [OR] = 0.204, 95% confidence interval [CI] 0.105-0.396) increased the likelihood of achieving MCID for SRS-22r Function. Preoperative SRS-22r Subtotal (OR = 0.211, 95% CI, 0.107-0.413), preoperative pelvic tilt (OR = 1.072, 95% CI, 1.012-1.136), preoperative pelvic incidence minus lumbar lordosis (OR = 0.965, 95% CI, 0.934-0.997), and postoperative sagittal vertical axis (OR = 0.985, 95% CI, 0.974-0.995) affected the likelihood of achieving MCID for the SRS-22r Subtotal.

CONCLUSION

Patients with poor preoperative health-related quality of life were more likely to achieve improvement in SRS-22r parameters after extensive corrective fusion surgery for ASD. Achieving postoperative sagittal alignment increased the likelihood of achieving MCID for the SRS-22r Subtotal domain.Level of Evidence: 3.

Predictors of 2-year reoperation in Medicare patients undergoing primary thoracolumbar deformity surgery

OBJECTIVE

This was a retrospective cohort study in which the authors used a nationally representative administrative database. Their goal was to identify the risk factors for reoperation in Medicare patients undergoing primary thoracolumbar adult spinal deformity (ASD) surgery. Previous literature reports estimate that 20% of patients undergoing thoracolumbar ASD correction undergo revision surgery within 2 years. Most published data discuss risk factors for revision surgery in the general population, but these have not been explored specifically in the Medicare population.

METHODS

Using the MarketScan Medicare Supplemental database, the authors identified patients who were diagnosed with a spinal deformity and underwent ASD surgery between 2007 and 2015. The interactions of patient demographics, surgical factors, and medical factors with revision surgery were investigated during the 2 years following primary ASD surgery. The authors excluded patients without Medicare insurance and those with any prior history of trauma or tumor.

RESULTS

Included in the data set were 2564 patients enrolled in Medicare who underwent ASD surgery between 2007 and 2015. The mean age at diagnosis with spinal deformity was 71.5 years. A majority of patients (68.5%) were female. Within 2 years of follow-up, 661 (25.8%) patients underwent reoperation. Preoperative osteoporosis (OR 1.58, p < 0.0001), congestive heart failure (OR 1.35, p = 0.0161), and paraplegia (OR 2.41, p < 0.0001) independently increased odds of revision surgery. The use of intraoperative bone morphogenetic protein was protective against reoperation (OR 0.71, p = 0.0371). Among 90-day postoperative complications, a wound complication was the strongest predictor of undergoing repeat surgery (OR 2.85, p = 0.0061). The development of a pulmonary embolism also increased the odds of repeat surgery (OR 1.84, p = 0.0435).

CONCLUSIONS

Approximately one-quarter of Medicare patients with ASD who underwent surgery required an additional spinal surgery within 2 years. Baseline comorbidities such as osteoporosis, congestive heart failure, and paraplegia, as well as short-term complications such as pulmonary embolism and wound complications significantly increased the odds of repeat surgery.

Revision strategies for failed adult spinal deformity surgery

PURPOSE

The aim of this study is to analyse the results of revision surgery for failed adult spinal deformity patients and to describe the surgical strategy selection process, based on the identification of the main clinical diagnosis responsible for failure.

METHODS

We retrospectively reviewed the clinical and radiological data of 77 consecutive patients treated in a 3-year time (2016-2019) for surgical revision of long fusion (more than five levels fused) for adult spinal deformity in a high-volume spine centre, divided into four groups based on the diagnosis: rod breakage (RB) group, proximal junctional failure (PJF) group, distal junctional failure (DJF) group and loss of correction (LOC) group with symptomatic sagittal or coronal malalignment (including iatrogenic flatback).

RESULTS

Seventy-seven patients met our inclusion criteria, with a female prevalence (66 F vs. 11 M). The mean age at revision surgery was 63. Fused levels before surgery were averagely 12, and revision added averagely two levels to the preexisting fusion area. Clinical status was apparently improved in ODI scores and VAS scores, while it was slightly worsened in SF36 scores. Different diagnosis groups have been addressed with different surgical strategies, according to the different surgical goals: interbody cages and multi-rod construct to improve stiffness and favour bony fusion, "kickstand" rod and "tie" rod to correct coronal and sagittal malalignment, specific rod contouring and proximal hooks in "claw" configuration to reduce mechanical stress at the proximal junctional area. Intraoperative complications occurred in 18% of patients and perioperative complications in 39%.

CONCLUSION

Revision surgery in long fusions for adult spinal deformity is a challenging field. Surgical strategy should always be planned carefully. A successful treatment is a direct consequence of a correct preoperative diagnosis, and surgery should address the primary cause of failure. All the above-mentioned surgical techniques and clinical skills should be part of surgeon's expertise when managing these patients. These slides can be retrieved under Electronic Supplementary Material.