A comparative cohort study of surgical approaches for adult spinal deformity at a minimum 2-year follow-up.

STUDY DESIGN: This study was a retrospective multi-center comparative cohort study. MATERIALS AND METHODS: A retrospective institutional database of operative adult spinal deformity patients was utilized. All fusions > 5 vertebral levels and including the sacrum/pelvis were eligible for inclusion. Revisions, 3 column osteotomies, and patients with < 2-year clinical follow-up were excluded. Patients were separated into 3 groups based on surgical approach: 1) posterior spinal fusion without interbody (PSF), 2) PSF with interbody (PSF-IB), and 3) anteroposterior (AP) fusion (anterior lumbar interbody fusion or lateral lumbar interbody fusion with posterior screw fixation). Intraoperative, radiographic, and clinical outcomes, as well as complications, were compared between groups with ANOVA and χ2 tests. RESULTS: One-hundred and thirty-eight patients were included for study (PSF, n = 37; PSF-IB, n = 44; AP, n = 57). Intraoperatively, estimated blood loss was similar between groups (p = 0.171). However, the AP group had longer operative times (547.5 min) compared to PSF (385.1) and PSF-IB (370.7) (p < 0.001). Additionally, fusion length was shorter in PSF-IB (11.4) compared to AP (13.6) and PSF (12.9) (p = 0.004). There were no differences between the groups in terms of change in alignment from preoperative to 2 years postoperative. There were no differences in clinical outcomes. While postoperative complications were largely similar between groups, operative complications were higher in the AP group (31.6%) compared to the PSF (5.4%) and PSF-IB (9.1) groups (p < 0.001). CONCLUSION: While there were differences in intraoperative outcomes (operative time and fusion length), there were no differences in postoperative clinical or radiographic outcomes. AP fusion was associated with a higher rate of operative complications.

Distal junctional kyphosis in adult cervical deformity patients: where does it occur?

PURPOSE: To evaluate the impact of the lowest instrumented vertebra (LIV) on Distal Junctional kyphosis (DJK) incidence in adult cervical deformity (ACD) surgery. METHODS: Prospectively collected data from ACD patients undergoing posterior or anterior-posterior reconstruction at 13 US sites was reviewed up to 2-years postoperatively (n = 140). Data was stratified into five groups by level of LIV: C6-C7, T1-T2, T3-Apex, Apex-T10, and T11-L2. DJK was defined as a kyphotic increase > 10° in Cobb angle from LIV to LIV-1. Analysis included DJK-free survival, covariate-controlled cox regression, and DJK incidence at 1-year follow-up. RESULTS: 25/27 cases of DJK developed within 1-year post-op. In patients with a minimum follow-up of 1-year (n = 102), the incidence of DJK by level of LIV was: C6-7 (3/12, 25.00%), T1-T2 (3/29, 10.34%), T3-Apex (7/41, 17.07%), Apex-T10 (8/11, 72.73%), and T11-L2 (4/8, 50.00%) (p < 0.001). DJK incidence was significantly lower in the T1-T2 LIV group (adjusted residual = -2.13), and significantly higher in the Apex-T10 LIV group (adjusted residual = 3.91). In covariate-controlled regression using the T11-L2 LIV group as reference, LIV selected at the T1-T2 level (HR = 0.054, p = 0.008) or T3-Apex level (HR = 0.081, p = 0.010) was associated with significantly lower risk of DJK. However, there was no difference in DJK risk when LIV was selected at the C6-C7 level (HR = 0.239, p = 0.214). CONCLUSION: DJK risk is lower when the LIV is at the upper thoracic segment than the lower cervical segment. DJK incidence is highest with LIV level in the lower thoracic or thoracolumbar junction.

Surgeons' risk perception in ASD surgery: The value of objective risk assessment on decision making and patient counselling.

BACKGROUND: Surgeons often rely on their intuition, experience and published data for surgical decision making and informed consent. Literature provides average values that do not allow for individualized assessments. Accurate validated machine learning (ML) risk calculators for adult spinal deformity (ASD) patients, based on 10 year multicentric prospective data, are currently available. The objective of this study is to assess surgeon ASD risk perception and compare it to validated risk calculator estimates. METHODS: Nine ASD complete (demographics, HRQL, radiology, surgical plan) preoperative cases were distributed online to 100 surgeons from 22 countries. Surgeons were asked to determine the risk of major complications and reoperations at 72 h, 90 d and 2 years postop, using a 0-100% risk scale. The same preoperative parameters circulated to surgeons were used to obtain ML risk calculator estimates. Concordance between surgeons' responses was analyzed using intraclass correlation coefficients (ICC) (poor < 0.5/excellent > 0.85). Distance between surgeons' and risk calculator predictions was assessed using the mean index of agreement (MIA) (poor < 0.5/excellent > 0.85). RESULTS: Thirty-nine surgeons (74.4% with > 10 years' experience), from 12 countries answered the survey. Surgeons' risk perception concordance was very low and heterogeneous. ICC ranged from 0.104 (reintervention risk at 72 h) to 0.316 (reintervention risk at 2 years). Distance between calculator and surgeon prediction was very large. MIA ranged from 0.122 to 0.416. Surgeons tended to overestimate the risk of major complications and reintervention in the first 72 h and underestimated the same risks at 2 years postop. CONCLUSIONS: This study shows that expert surgeon ASD risk perception is heterogeneous and highly discordant. Available validated ML ASD risk calculators can enable surgeons to provide more accurate and objective prognosis to adjust patient expectations, in real time, at the point of care.

Primary mobile vertebral column sarcomas: Prognostic factors vary by histologic subtypes.

BACKGROUND: Primary sarcomas originating from the mobile spine portends a particularly sinister outcome. Rarity of the disease process has resulted in inconsistent data due to small sample size and heterogeneity in patient selection and analytics. METHODS: Surveillance, Epidemiology and End Result (SEER) database from 1975 to 2017 was queried to report incidence and survival data in 712 patients in the United States. Kaplan-Meier and Cox Regression were used to determine the prognostic factors affecting survival. RESULTS: Incidence of spinal sarcoma was 0.019 per 100,000 persons in 2017 and has not significantly changed since 2000 (p > 0.05). Disease-specific 5-year survival for the entire cohort was 57%. Osteosarcoma has the worst 5-year survival (39%) and chondrosarcoma has the best 5-year survival (69%). Independent predictors of survival for the entire cohort included age, grade, and stage. Stage was an independent predictor of survival for every histologic subtype. Additional predictors of survival for spinal osteosarcoma, Ewing sarcoma, and chondrosarcoma included age, size, and grade, respectively. CONCLUSIONS: The current study is an analysis of a population-based registry reporting incidence survival data for patients with sarcoma of mobile vertebral column. Survival and prognostic factors vary by histologic subtypes. There is lack of improvement in survival over the last three decades.

Intervertebral Disc Mechanics With Nucleotomy: Differences Between Simple and Dual Loading.

Painful herniated discs are treated surgically by removing extruded nucleus pulposus (NP) material (nucleotomy). NP removal through enzymatic digestion is also commonly performed to initiate degenerative changes to study potential biological repair strategies. Experimental and computational studies have shown a decrease in disc stiffness with nucleotomy under single loading modalities, such as compression-only or bending-only loading. However, studies that apply more physiologically relevant loading conditions, such as compression in combination with bending or torsion, have shown contradicting results. We used a previously validated bone-disc-bone finite element model (Control) to create a Nucleotomy model to evaluate the effect of dual loading conditions (compression with torsion or bending) on intradiscal deformations. While disc joint stiffness decreased with nucleotomy under single loading conditions, as commonly reported in the literature, dual loading resulted in an increase in bending stiffness. More specifically, dual loading resulted in a 40% increase in bending stiffness under flexion and extension and a 25% increase in stiffness under lateral bending. The increase in bending stiffness was due to an increase and shift in compressive stress, where peak stresses migrated from the NP-annulus interface to the outer annulus. In contrast, the decrease in torsional stiffness was due to greater fiber reorientation during compression. In general, large radial strains were observed with nucleotomy, suggesting an increased risk for delamination or degenerative remodeling. In conclusion, the effect of nucleotomy on disc mechanics depends on the type and complexity of applied loads.

Artificial intelligence clustering of adult spinal deformity sagittal plane morphology predicts surgical characteristics, alignment, and outcomes.

PURPOSE: AI algorithms have shown promise in medical image analysis. Previous studies of ASD clusters have analyzed alignment metrics-this study sought to complement these efforts by analyzing images of sagittal anatomical spinopelvic landmarks. We hypothesized that an AI algorithm would cluster preoperative lateral radiographs into groups with distinct morphology. METHODS: This was a retrospective review of a multicenter, prospectively collected database of adult spinal deformity. A total of 915 patients with adult spinal deformity and preoperative lateral radiographs were included. A 2 × 3, self-organizing map-a form of artificial neural network frequently employed in unsupervised classification tasks-was developed. The mean spine shape was plotted for each of the six clusters. Alignment, surgical characteristics, and outcomes were compared. RESULTS: Qualitatively, clusters C and D exhibited only mild sagittal plane deformity. Clusters B, E, and F, however, exhibited marked positive sagittal balance and loss of lumbar lordosis. Cluster A had mixed characteristics, likely representing compensated deformity. Patients in clusters B, E, and F disproportionately underwent 3-CO. PJK and PJF were particularly prevalent among clusters A and E. Among clusters B and F, patients who experienced PJK had significantly greater positive sagittal balance than those who did not. CONCLUSIONS: This study clustered preoperative lateral radiographs of ASD patients into groups with highly distinct overall spinal morphology and association with sagittal alignment parameters, baseline HRQOL, and surgical characteristics. The relationship between SVA and PJK differed by cluster. This study represents significant progress toward incorporation of computer vision into clinically relevant classification systems in adult spinal deformity. LEVEL OF EVIDENCE IV: Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Use of rhBMP-2 for adult spinal deformity surgery: patterns of usage and changes over the past decade.

OBJECTIVE: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to increase fusion rates; however, cost, limited FDA approval, and possible complications impact its use. Decisions regarding rhBMP-2 use and changes over time have not been well defined. In this study, the authors aimed to assess changes in rhBMP-2 use for adult spinal deformity (ASD) surgery over the past decade. METHODS: A retrospective review of the International Spine Study Group prospective multicenter database was performed to identify ASD patients treated surgically from 2008 to 2018. For assessment of rhBMP-2 use over time, 3 periods were created: 2008-2011, 2012-2015, and 2016-2018. RESULTS: Of the patients identified, 1180 met inclusion criteria, with a mean age 60 years and 30% of patients requiring revision surgery; rhBMP-2 was used in 73.9% of patients overall. The mean rhBMP-2 dose per patient was 23.6 mg. Patients receiving rhBMP-2 were older (61 vs 58 years, p < 0.001) and had more comorbidities (Charlson Comorbidity Index 1.9 vs 1.4, p < 0.001), a higher rate of the Scoliosis Research Society-Schwab pelvic tilt modifier (> 0; 68% vs 62%, p = 0.026), a greater deformity correction (change in pelvic incidence minus lumbar lordosis 15° vs 12°, p = 0.01), and more levels fused (8.9 vs 7.9, p = 0.003). Over the 3 time periods, the overall rate of rhBMP-2 use increased and then stabilized (62.5% vs 79% vs 77%). Stratified analysis showed that after an overall increase in rhBMP-2 use, only patients who were younger than 50 years, those who were smokers, those who received a three-column osteotomy (3CO), and patients who underwent revision sustained an increased rate of rhBMP-2 use between the later two periods. No similar increases were noted for older patients, nonsmokers, primary surgery patients, and patients without a 3CO. The total rhBMP-2 dose decreased over time (26.6 mg vs 24.8 mg vs 20.7 mg, p < 0.001). After matching patients by preoperative alignment, 215 patients were included, and a significantly lower rate of complications leading to revision surgery was observed within the 2012-2015 period compared with the 2008-2011 (21.4% vs 13.0%, p = 0.029) period, while rhBMP-2 was increasingly used (80.5% vs 66.0%, p = 0.001). There was a trend toward a lower rate of pseudarthrosis for patients in the 2012-2015 period, but this difference did not reach statistical significance (7% vs 4.2%, p = 0.283). CONCLUSIONS: The authors found that rhBMP-2 was used in the majority of ASD patients and was more commonly used in those with greater deformity correction. Additionally, over the last 10 years, rhBMP-2 was increasingly used for ASD patients, but the dose has decreased.

The efficacy and safety of ipriflavone in postmenopausal women with osteopenia or osteoporosis: A systematic review and meta-analysis.

OBJECTIVES: Ipriflavone (IP) is one of the over-the-counter drugs and found in foods, which is available for prevention of osteoporosis (OP) since 1989 in over 22 countries. Although some clinical trials have suggested that IP is appropriate for treatment of OP, there continues to be controversy regarding the efficacy and safety due to some contradictory reports. With the wide usage of IP for osteoporotic women, there is a critical need for evaluation of the evidence for IP in clinical practice. METHODS AND MATERIALS: We searched randomized control trials (RCTs) in PubMed, CENTRAL and CNKI which used the regimen of IP in postmenopausal women with osteopenia or OP. The efficacy referred to the absolute change and relative change in bone mineral density (BMD) and bone turnover markers. The safety profiles were associated with adverse events and the number of subject withdrawals due to adverse reactions. RESULTS: Eleven RCTs (n = 1605) met the eligibility criteria were included. The increase of the BMD in lumbar spine of the IP group is greater than that of the placebo group (random effect model: SMD = 0.36; 95%CI= (0.09, 0.62)). For safety profile, most frequent reactions are gastrointestinal symptoms, but withdrawals due to adverse reactions are similar in both the IP group and placebo control at the same time intervals. CONCLUSIONS: IP significantly increases BMD and has inhibitory effect on bone resorption markers in postmenopausal women with osteopenia or OP. Gastrointestinal symptoms may occur, but adverse drug withdrawal events were not statistically increased when compared with placebo group.

The spino-pelvic ratio: a novel global sagittal parameter associated with clinical outcomes in adult spinal deformity patients.

PURPOSE: Analysis of interactions of spinal alignment metrics may uncover novel alignment parameters, similar to PI-LL. This study utilized a data-driven approach to hypothesis generation by testing all possible division interactions between spinal alignment parameters. METHODS: This study was a retrospective cohort analysis. In total, 1439 patients with baseline ODI were included for hypothesis generation. In total, 666 patients had 2-year postoperative follow-up and were included for validation. All possible combinations of division interactions between baseline metrics were assessed with linear regression against baseline ODI. RESULTS: From 247 raw alignment metrics, 32,398 division interactions were considered in hypothesis generation. Conceptually, the TPA divided by PI is a measure of the relative alignment of the line connecting T1 to the femoral head and the line perpendicular to the sacral endplate. The mean TPA/PI was 0.41 at baseline and 0.30 at 2 years postoperatively. Higher TPA/PI was associated with worse baseline ODI (p < 0.0001). The change in ODI at 2 years was linearly associated with the change in TPA/PI (p = 0.0172). The optimal statistical grouping of TPA/PI was low/normal (≤ 0.2), medium (0.2-0.4), and high (> 0.4). The R-squared for ODI against categorical TPA/PI alone (0.154) was directionally higher than that for each of the individual Schwab modifiers (SVA: 0.138, PI-LL 0.111, PT 0.057). CONCLUSION: This study utilized a data-driven approach for hypothesis generation and identified the spino-pelvic ratio (TPA divided by PI) as a promising measure of sagittal spinal alignment among ASD patients. Patients with SPR > 0.2 exhibited inferior ODI scores. LEVEL OF EVIDENCE: III.

Facet Joints of the Spine: Structure-Function Relationships, Problems and Treatments, and the Potential for Regeneration.

The zygapophysial joint, a diarthrodial joint commonly referred to as the facet joint, plays a pivotal role in back pain, a condition that has been a leading cause of global disability since 1990. Along with the intervertebral disc, the facet joint supports spinal motion and aids in spinal stability. Highly susceptible to early development of osteoarthritis, the facet is responsible for a significant amount of pain in the low-back, mid-back, and neck regions. Current noninvasive treatments cannot offer long-term pain relief, while invasive treatments can relieve pain but fail to preserve joint functionality. This review presents an overview of the facet in terms of its anatomy, functional properties, problems, and current management strategies. Furthermore, this review introduces the potential for regeneration of the facet and particular engineering strategies that could be employed as a long-term treatment.

The evidence-based approach for surgical complications in the treatment of lumbar disc herniation.

PURPOSE: The purpose of this article is to review the evidence-based approach for surgical complications following disc herniation. METHODS: A search of the primary English literature was conducted for research examining the outcomes and complications of surgical discectomy. Special regard was given to high-quality prospective randomized studies. RESULTS: The most commonly reported complications of surgical treatment of disc herniation are included in this review. Medical complications, and surgical complications including infection, durotomy, neurological injury, symptomatic re-herniation, and revision surgery are defined and systematically reviewed in detail for incidence, evaluation, and management. CONCLUSION: This article provides the clinician and surgeon with a review of the evidence-based evaluation and management of surgical complications following disc herniation, offering best practice guidelines for informed discussions with patients in shared decision-making.

Xipho-pubic angle (XPA) correlates with patient's reported outcomes in a population of adult spinal deformity: results from a multi-center cohort study.

STUDY DESIGN: Retrospective multi-center cohort study. PURPOSE: Sagittal misalignment causes changes in the abdominal shape. Xipho-pubic angle (XPA) has been previously described to radiographically evaluate the shape of the abdominal cavity in patients with spine deformity. The aims of this study are to evaluate the correlation of XPA-to-spinopelvic sagittal parameters and to patients' health-related quality-of-life (HRQoL) scores. METHODS: 278 patients from a multi-center database with diagnosis adult spinal deformity (ASD) (one or more of: coronal Cobb angle > 20°, sagittal vertical axis (SVA) > 50 mm, pelvic tilt (PT) > 25°, and thoracic kyphosis > 60°) were included. Cut-off values for moderate and severe disability (ODI-Oswestry Disability Index-20 and 40%) were calculated. Pearson's correlation was tested between XPA and spinopelvic parameters and between XPA and HRQoL scores. RESULTS: The cut-off value of XPA to identify ODI severe disability (40/100) was identified with XPA smaller than 103°; minimal (20/100) disability was identified by XPA greater than 113°. XPA showed strong correlation to sagittal spinopelvic parameters-PT, SVA, lumbar lordosis (LL), pelvic incidence (PI) minus LL-and to HRQoL scores-ODI, SF-36 PCS and SRS-22 activity and pain. XPA was the parameter with the strongest correlation to HRQoL scores. CONCLUSIONS: Xipho-pubic angle reflects changes in spinal changes and has strong correlation to HRQoL and spinopelvic parameters. It can discriminate between patients with minimal, moderate, and severe disability as measured by ODI scores. These slides can be retrieved under Electronic Supplementary Material.

Prospective multi-centric evaluation of upper cervical and infra-cervical sagittal compensatory alignment in patients with adult cervical deformity.

PURPOSE: Reciprocal mechanisms for standing alignment have been described in thoraco-lumbar deformity but have not been studied in patients with primary cervical deformity (CD). The purpose of this study is to report upper- and infra-cervical sagittal compensatory mechanisms in patients with CD and evaluate their changes post-operatively. METHODS: Global spinal alignment was studied in a prospective database of operative CD patients. Inclusion criteria were any of the following: cervical kyphosis (CK) > 10°, cervical scoliosis > 10°, cSVA (C2-C7 Sagittal vertical axis) > 4 cm or CBVA (Chin Brow Vertical Angle) > 25°. For this study, patients who had previous fusion outside C2 to T4 segments were excluded. Patients were sub-classified by increasing severity of cervical kyphosis [CL (cervical lordosis): < 0°, CK-low 0°-10°, CK-high > 10°] and cSVA (cSVA-low 0-4 cm, cSVA-mid 4-6 cm, cSVA-high > 6 cm) and were compared for pre- and 3-month post-operative regional and global sagittal alignment to determine compensatory recruitment. RESULTS: 75 CD patients (mean age 61.3 years, 56% women) were included. Patients with progressively larger CK had a progressive increase in C0-C2 (CL = 34°, CK-low = 37°, CK-high = 44°, p = 0.004), C2Slope and T1Slope-CL (p < 0.05). As the cSVA increased, there was progressive increase in C2Slope, T1Slope and TS-CL (p < 0.05) and patients compensated through increasing C0-C2 (cSVA-low = 33°, cSVA-mid = 40°, cSVA-high = 43°, p = 0.007) and pelvic tilt (cSVA-low = 14.9°, cSVA-mid = 24.1°, cSVA-high = 24.9°, p = 0.02). At 3 months post-op, with significant improvement in cervical alignment, there was relaxation of C0-C2 (39°-35°, p = 0.01) which positively correlated with magnitude of deformity correction. CONCLUSIONS: Patients with cervical malalignment compensate with upper cervical hyper-lordosis, presumably for the maintenance of horizontal gaze. As cSVA increases, patients also tend to exhibit increased pelvic retroversion. Following surgical treatment, there was relaxation of upper cervical compensation.

Development of a validated computer-based preoperative predictive model for pseudarthrosis with 91% accuracy in 336 adult spinal deformity patients.

OBJECTIVEPseudarthrosis can occur following adult spinal deformity (ASD) surgery and can lead to instrumentation failure, recurrent pain, and ultimately revision surgery. In addition, it is one of the most expensive complications of ASD surgery. Risk factors contributing to pseudarthrosis in ASD have been described; however, a preoperative model predicting the development of pseudarthrosis does not exist. The goal of this study was to create a preoperative predictive model for pseudarthrosis based on demographic, radiographic, and surgical factors.METHODSA retrospective review of a prospectively maintained, multicenter ASD database was conducted. Study inclusion criteria consisted of adult patients (age ≥ 18 years) with spinal deformity and surgery for the ASD. From among 82 variables assessed, 21 were used for model building after applying collinearity testing, redundancy, and univariable predictor importance ≥ 0.90. Variables included demographic data along with comorbidities, modifiable surgical variables, baseline coronal and sagittal radiographic parameters, and baseline scores for health-related quality of life measures. Patients groups were determined according to their Lenke radiographic fusion type at the 2-year follow-up: bilateral or unilateral fusion (union) or pseudarthrosis (nonunion). A decision tree was constructed, and internal validation was accomplished via bootstrapped training and testing data sets. Accuracy and the area under the receiver operating characteristic curve (AUC) were calculated to evaluate the model.RESULTSA total of 336 patients were included in the study (nonunion: 105, union: 231). The model was 91.3% accurate with an AUC of 0.94. From 82 initial variables, the top 21 covered a wide range of areas including preoperative alignment, comorbidities, patient demographics, and surgical use of graft material.CONCLUSIONSA model for predicting the development of pseudarthrosis at the 2-year follow-up was successfully created. This model is the first of its kind for complex predictive analytics in the development of pseudarthrosis for patients with ASD undergoing surgical correction and can aid in clinical decision-making for potential preventative strategies.

Three-column osteotomy for correction of cervical and cervicothoracic deformities: alignment changes and early complications in a multicenter prospective series of 23 patients.

PURPOSE: Three-column osteotomy (3CO), including pedicle subtraction osteotomy (PSO) and vertebral column resection (VCR), can provide powerful alignment correction for adult cervical deformity (ACD). Our objective was to assess alignment changes and early complications associated with 3CO for ACD. METHODS: ACD patients treated with 3CO with minimum 90-day follow-up were identified from a prospectively collected multicenter ACD database. Complications within 90-days of surgery and pre- and postoperative radiographs were collected. RESULTS: All 23 ACD patients treated with 3CO (14 PSO/9 VCR) had minimum 90-day follow-up (mean age 62.3 years, previous cervical/cervicothoracic instrumentation in 52.2% and thoracic/thoracolumbar instrumentation in 47.8%). The primary diagnosis was kyphosis in 91.3% and coronal deformity in 8.7%. The mean number of fusion levels was 12 (range 6-18). The most common 3CO levels were T1 (39.1%), T2 (30.4%) and T3 (21.7%). Eighteen (12 major/6 minor) complications affected 13 (56.5%) patients. The most common complications were neurologic deficit (17.4%), wound infection (8.7%), distal junctional kyphosis (DJK 8.7%), and cardiorespiratory failure (8.7%). Three (13.0%) patients required re-operation within 90-days (1 each for nerve root motor deficit, DJK, and implant pain/prominence). Cervical alignment improved significantly following 3CO, including cervical lordosis (-2.8° to -12.9°, p = 0.036), C2-7 sagittal vertical axis (64.6-42.3 mm, p < 0.001), and T1 slope minus cervical lordosis (46.4°-27.0°, p < 0.001). CONCLUSIONS: Among 23 ACD patients treated with 3CO, cervical alignment improved significantly following surgery. Thirteen (56.5%) patients had at least one complication. The most common complications were neurologic deficit, infection, DJK, and cardiorespiratory failure.

Cervical sagittal deformity develops after PJK in adult thoracolumbar deformity correction: radiographic analysis utilizing a novel global sagittal angular parameter, the CTPA.

PURPOSE: To describe reciprocal changes in cervical alignment after adult spinal deformity (ASD) correction and subsequent development of proximal junctional kyphosis (PJK). This study also investigated these changes using two novel global sagittal angular parameters, cervical-thoracic pelvic angle (CTPA) and the T1 pelvic angle (TPA). METHODS: Multicenter, retrospective consecutive case series of ASD patients undergoing thoracolumbar three-column osteotomy (3CO) with fusion to the pelvis. Radiographs were analyzed at baseline and 1 year post-operatively. Patients were substratified into upper thoracic (UT; UIV T6 and above) and lower thoracic (LT; UIV below T6). PJK was defined by >10° angle between UIV and UIV + 2 and >10° change in the angle from baseline to post-op. RESULTS: PJK developed in 29 % (78 of 267) of patients. CTPA was linearly correlated with cervical plumbline (CPL) as a measure of cervical sagittal alignment (R = 0.826, p < 0.001). PJK patients had significantly greater post-operative CTPA and SVA than patients without PJK (NPJK) (p = 0.042; p = 0.021). For UT (n = 141) but not LT (n = 136), PJK patients at 1 year had larger CTPA (4.9° vs. 3.7°, p = 0.015) and CPL (5.1 vs. 3.8 cm, p = 0.022) than NPJK patients, despite similar corrections in PT and PI-LL. CONCLUSIONS: The prevalence of PJK was 29 % at 1 year follow-up. CTPA, which correlates with CPL as a global analog of cervical sagittal balance, and TPA describe relative proportions of cervical and thoracolumbar deformities. Patients who develop PJK in the upper thoracic spine after thoracolumbar 3CO also develop concomitant cervical sagittal deformity, with increases in CPL and CTPA.

Selecting caudal fusion levels: 2 year functional and stiffness outcomes with matched pairs analysis in multilevel fusion to L5 versus S1.

PURPOSE: Controversy persists as to whether to end multilevel thoracolumbar fusions caudally at L5 or S1. Some argue that stopping at L5 may preserve greater function, but there are few data comparing functional limitations due to lumbar stiffness in patients with fusion to L5 versus S1. The aim of this study was to evaluate whether patients undergoing multilevel thoracolumbar fusions with an L5 caudal endpoint have a better lumbosacral function than patients with an S1 caudal endpoint. METHODS: Patients undergoing successful thoracolumbar fusion of 5 or more levels to L5 or S1, with solid fusion at 2 year follow-up, were examined from a single European center in addition to a multi-center North American database of 237 patients. In total, 40 patients with a distal stopping point of L5 were matched with a subset of 40 patients with a distal endpoint of S1 ± pelvic fixation. The L5 and S1 groups were matched for the final Oswestry Disability Index (ODI), Sagittal Vertical Axis (SVA C7-S1), number of fusion levels, and age. Impacts of lumbar stiffness on function as measured by the Lumbar Stiffness Disability Index (LSDI) were compared using the conditional logistic regression. RESULTS: After matching, there was no significant difference between the S1 and L5 groups for the final ODI (29.22 ± 21.6 for S1 versus 29.21 ± 21.7 for L5; p = 0.98), SVA (29.5 ± 40.3 mm for S1 versus 33.7 ± 37.1 mm for L5; p = 0.97), mean age (61.6 ± 11.0 years for S1 versus 58.3 ± 12.6 years for L5; p = 0.23), and number of fusion levels (9.7 ± 3.3 levels for S1 versus 9.0 ± 3 levels for L5; p = 0.34). The final 2-year postoperative LSDI scores were not significantly different between the S1 group (28.08 ± 21.47) and L5 group (29.21 ± 21.66) (hazard ratio 0.99, 95 % CI 0.97-1.03, p = 0.81). CONCLUSION: The analysis of patients with multilevel thoracolumbar fusions demonstrated that after minimum 2 year follow-up, self-reported functional impacts of lumbar stiffness were not significantly different between the patients with distal endpoints of L5 versus S1. The choice of distal fusion level of L5 does not appear to retain sufficient spinal flexibility to substantially affect postoperative function. LEVEL OF EVIDENCE: Level III.

Potential of predictive computer models for preoperative patient selection to enhance overall quality-adjusted life years gained at 2-year follow-up: a simulation in 234 patients with adult spinal deformity.

OBJECTIVE Patients with adult spinal deformity (ASD) experience significant quality of life improvements after surgery. Treatment, however, is expensive and complication rates are high. Predictive analytics has the potential to use many variables to make accurate predictions in large data sets. A validated minimum clinically important difference (MCID) model has the potential to assist in patient selection, thereby improving outcomes and, potentially, cost-effectiveness. METHODS The present study was a retrospective analysis of a multiinstitutional database of patients with ASD. Inclusion criteria were as follows: age ≥ 18 years, radiographic evidence of ASD, 2-year follow-up, and preoperative Oswestry Disability Index (ODI) > 15. Forty-six variables were used for model training: demographic data, radiographic parameters, surgical variables, and results on the health-related quality of life questionnaire. Patients were grouped as reaching a 2-year ODI MCID (+MCID) or not (-MCID). An ensemble of 5 different bootstrapped decision trees was constructed using the C5.0 algorithm. Internal validation was performed via 70:30 data split for training/testing. Model accuracy and area under the curve (AUC) were calculated. The mean quality-adjusted life years (QALYs) and QALYs gained at 2 years were calculated and discounted at 3.5% per year. The QALYs were compared between patients in the +MCID and -MCID groups. RESULTS A total of 234 patients met inclusion criteria (+MCID 129, -MCID 105). Sixty-nine patients (29.5%) were included for model testing. Predicted versus actual results were 50 versus 40 for +MCID and 19 versus 29 for -MCID (i.e., 10 patients were misclassified). Model accuracy was 85.5%, with 0.96 AUC. Predicted results showed that patients in the +MCID group had significantly greater 2-year mean QALYs (p = 0.0057) and QALYs gained (p = 0.0002). CONCLUSIONS A successful model with 85.5% accuracy and 0.96 AUC was constructed to predict which patients would reach ODI MCID. The patients in the +MCID group had significantly higher mean 2-year QALYs and QALYs gained. This study provides proof of concept for using predictive modeling techniques to optimize patient selection in complex spine surgery.

Male sex may not be associated with worse outcomes in primary all-posterior adult spinal deformity surgery: a multicenter analysis.

OBJECTIVE Adolescent spine deformity studies have shown that male patients require longer surgery and have greater estimated blood loss (EBL) and complications compared with female patients. No studies exist to support this relationship in adult spinal deformity (ASD). The purpose of this study was to investigate associations between sex and complications, deformity correction, and health-related quality of life (HRQOL) in patients with ASD. It was hypothesized that male ASD patients would have greater EBL, longer surgery, and more complications than female ASD patients. METHODS A multicenter ASD cohort was retrospectively queried for patients who underwent primary posterior-only instrumented fusions with a minimum of 5 levels fused. The minimum follow-up was 2 years. Primary outcomes were EBL, operative time, intra-, peri-, and postoperative complications, radiographic correction, and HRQOL outcomes (Oswestry Disability Index, SF-36, and Scoliosis Research Society-22r Questionnaire). Poisson multivariate regression was used to control for age, comorbidities, and levels fused. RESULTS Ninety male and 319 female patients met the inclusion criteria. Male patients had significantly greater mean EBL (2373 ml vs 1829 ml, p = 0.01). The mean operative time, transfusion requirements, and final radiographic measurements did not differ between sexes. Similarly, changes in HRQOL showed no significant differences. Finally, there were no sex differences in the incidence of complications (total, major, or minor) at any time point after controlling for age, body mass index, comorbidities, and levels fused. CONCLUSIONS Despite higher EBL, male ASD patients did not experience more complications or require less deformity correction at the 2-year follow-up. HRQOL scores similarly showed no sex differences. These findings differ from adolescent deformity studies, and surgeons can counsel patients that sex is unlikely to influence the outcomes and complication rates of primary all-posterior ASD surgery.

Minimally Invasive Lateral Approach for the Management of Adult Degenerative Scoliosis.

Minimally invasive lateral releases for the correction of lumbar scoliosis are becoming an increasingly common treatment alternative to posterior osteotomies or surgery via an open anterior approach. Minimally invasive approaches minimize blood loss and morbidity, which may be important in older patients who often have substantial comorbidities. Anterior column realignment allows lumbar lordosis to be restored via a minimally invasive lateral approach, which restores sagittal balance and is correlated with improvements in health-related quality of life. Surgeons should understand the development of, the indications for, the surgical technique for, and the complications and early clinical outcomes of the minimally invasive lateral approach to the spine.