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Justin S. Smith, Christopher I. Shaffrey, Virginie Lafage, Frank Schwab, Justin K. Scheer, Themistocles Protopsaltis, Eric Klineberg, Munish Gupta, Richard Hostin, Kai-Ming G. Fu, Gregory M. Mundis Jr., Han Jo Kim, Vedat Deviren, Alex Soroceanu, Robert A. Hart, Douglas C. Burton, Shay Bess, Christopher P. Ames and the International Spine Study Group

OBJECT

Although recent studies suggest that average clinical outcomes are improved following surgery for selected adult spinal deformity (ASD) patients, these outcomes span a broad range. Few studies have specifically addressed factors that may predict favorable clinical outcomes. The objective of this study was to compare patients with ASD with best versus worst clinical outcomes following surgical treatment to identify distinguishing factors that may prove useful for patient counseling and optimization of clinical outcomes.

METHODS

This is a retrospective review of a prospectively collected, multicenter, database of consecutively enrolled patients with ASD who were treated operatively. Inclusion criteria were age > 18 years and ASD. For patients with a minimum of 2-year follow-up, those with best versus worst outcomes were compared separately based on Scoliosis Research Society-22 (SRS-22) and Oswestry Disability Index (ODI) scores. Only patients with a baseline SRS-22 ≤ 3.5 or ODI ≥ 30 were included to minimize ceiling/floor effects. Best and worst outcomes were defined for SRS-22 (≥ 4.5 and ≤ 2.5, respectively) and ODI (≤ 15 and ≥ 50, respectively).

RESULTS

Of 257 patients who met the inclusion criteria, 227 (88%) had complete baseline and 2-year follow-up SRS-22 and ODI outcomes scores and radiographic imaging and were analyzed in the present study. Of these 227 patients, 187 had baseline SRS-22 scores ≤ 3.5, and 162 had baseline ODI scores ≥ 30. Forthe SRS-22, best and worst outcomes criteria were met at follow-up for 25 and 27 patients, respectively. For the ODI, best and worst outcomes criteria were met at follow-up for 43 and 51 patients, respectively. With respect to the SRS-22, compared with best outcome patients, those with worst outcomes had higher baseline SRS-22 scores (p < 0.0001), higher prevalence of baseline depression (p < 0.001), more comorbidities (p = 0.012), greater prevalence of prior surgery (p = 0.007), a higher complication rate (p = 0.012), and worse baseline deformity (sagittal vertical axis [SVA], p = 0.045; pelvic incidence [PI] and lumbar lordosis [LL] mismatch, p = 0.034). The best-fit multivariate model for SRS-22 included baseline SRS-22 (p = 0.033), baseline depression (p = 0.012), and complications (p = 0.030). With respect to the ODI, compared with best outcome patients, those with worst outcomes had greater baseline ODI scores (p < 0.001), greater baseline body mass index (BMI; p = 0.002), higher prevalence of baseline depression (p < 0.028), greater baseline SVA (p = 0.016), a higher complication rate (p = 0.02), and greater 2-year SVA (p < 0.001) and PI-LL mismatch (p = 0.042). The best-fit multivariate model for ODI included baseline ODI score (p < 0.001), 2-year SVA (p = 0.014) and baseline BMI (p = 0.037). Age did not distinguish best versus worst outcomes for SRS-22 or ODI (p > 0.1).

CONCLUSIONS

Few studies have specifically addressed factors that distinguish between the best versus worst clinical outcomes for ASD surgery. In this study, baseline and perioperative factors distinguishing between the best and worst outcomes for ASD surgery included several patient factors (baseline depression, BMI, comorbidities, and disability), as well as residual deformity (SVA), and occurrence of complications. These findings suggest factors that may warrant greater awareness among clinicians to achieve optimal surgical outcomes for patients with ASD.

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Justin S. Smith, Eric Klineberg, Virginie Lafage, Christopher I. Shaffrey, Frank Schwab, Renaud Lafage, Richard Hostin, Gregory M. Mundis Jr., Thomas J. Errico, Han Jo Kim, Themistocles S. Protopsaltis, D. Kojo Hamilton, Justin K. Scheer, Alex Soroceanu, Michael P. Kelly, Breton Line, Munish Gupta, Vedat Deviren, Robert Hart, Douglas C. Burton, Shay Bess, Christopher P. Ames and the International Spine Study Group

OBJECTIVE

Although multiple reports have documented significant benefit from surgical treatment of adult spinal deformity (ASD), these procedures can have high complication rates. Previously reported complications rates associated with ASD surgery are limited by retrospective design, single-surgeon or single-center cohorts, lack of rigorous data on complications, and/or limited follow-up. Accurate definition of complications associated with ASD surgery is important and may serve as a resource for patient counseling and efforts to improve the safety of patient care. The authors conducted a study to prospectively assess the rates of complications associated with ASD surgery with a minimum 2-year follow-up based on a multicenter study design that incorporated standardized data-collection forms, on-site study coordinators, and regular auditing of data to help ensure complete and accurate reporting of complications. In addition, they report age stratification of complication rates and provide a general assessment of factors that may be associated with the occurrence of complications.

METHODS

As part of a prospective, multicenter ASD database, standardized forms were used to collect data on surgery-related complications. On-site coordinators and central auditing helped ensure complete capture of complication data. Inclusion criteria were age older than 18 years, ASD, and plan for operative treatment. Complications were classified as perioperative (within 6 weeks of surgery) or delayed (between 6 weeks after surgery and time of last follow-up), and as minor or major. The primary focus for analyses was on patients who reached a minimum follow-up of 2 years.

RESULTS

Of 346 patients who met the inclusion criteria, 291 (84%) had a minimum 2-year follow-up (mean 2.1 years); their mean age was 56.2 years. The vast majority (99%) had treatment including a posterior procedure, 25% had an anterior procedure, and 19% had a 3-column osteotomy. At least 1 revision was required in 82 patients (28.2%). A total of 270 perioperative complications (145 minor; 125 major) were reported, with 152 patients (52.2%) affected, and a total of 199 delayed complications (62 minor; 137 major) were reported, with 124 patients (42.6%) affected. Overall, 469 complications (207 minor; 262 major) were documented, with 203 patients (69.8%) affected. The most common complication categories included implant related, radiographic, neurological, operative, cardiopulmonary, and infection. Higher complication rates were associated with older age (p = 0.009), greater body mass index (p ≤ 0.031), increased comorbidities (p ≤ 0.007), previous spine fusion (p = 0.029), and 3-column osteotomies (p = 0.036). Cases in which 2-year follow-up was not achieved included 2 perioperative mortalities (pulmonary embolus and inferior vena cava injury).

CONCLUSIONS

This study provides an assessment of complications associated with ASD surgery based on a prospective, multicenter design and with a minimum 2-year follow-up. Although the overall complication rates were high, in interpreting these findings, it is important to recognize that not all complications are equally impactful. This study represents one of the most complete and detailed reports of perioperative and delayed complications associated with ASD surgery to date. These findings may prove useful for treatment planning, patient counseling, benchmarking of complication rates, and efforts to improve the safety and cost-effectiveness of patient care.

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Khoi D. Than, Paul Park, Kai-Ming Fu, Stacie Nguyen, Michael Y. Wang, Dean Chou, Pierce D. Nunley, Neel Anand, Richard G. Fessler, Christopher I. Shaffrey, Shay Bess, Behrooz A. Akbarnia, Vedat Deviren, Juan S. Uribe, Frank La Marca, Adam S. Kanter, David O. Okonkwo, Gregory M. Mundis Jr., Praveen V. Mummaneni and the International Spine Study Group

OBJECTIVE

Minimally invasive surgery (MIS) techniques are increasingly used to treat adult spinal deformity. However, standard minimally invasive spinal deformity techniques have a more limited ability to restore sagittal balance and match the pelvic incidence–lumbar lordosis (PI-LL) than traditional open surgery. This study sought to compare “best” versus “worst” outcomes of MIS to identify variables that may predispose patients to postoperative success.

METHODS

A retrospective review of minimally invasive spinal deformity surgery cases was performed to identify parameters in the 20% of patients who had the greatest improvement in Oswestry Disability Index (ODI) scores versus those in the 20% of patients who had the least improvement in ODI scores at 2 years' follow-up.

RESULTS

One hundred four patients met the inclusion criteria, and the top 20% of patients in terms of ODI improvement at 2 years (best group, 22 patients) were compared with the bottom 20% (worst group, 21 patients). There were no statistically significant differences in age, body mass index, pre- and postoperative Cobb angles, pelvic tilt, pelvic incidence, levels fused, operating room time, and blood loss between the best and worst groups. However, the mean preoperative ODI score was significantly higher (worse disability) at baseline in the group that had the greatest improvement in ODI score (58.2 vs 39.7, p < 0.001). There was no difference in preoperative PI-LL mismatch (12.8° best vs 19.5° worst, p = 0.298). The best group had significantly less postoperative sagittal vertical axis (SVA; 3.4 vs 6.9 cm, p = 0.043) and postoperative PI-LL mismatch (10.4° vs 19.4°, p = 0.027) than the worst group. The best group also had better postoperative visual analog scale back and leg pain scores (p = 0.001 and p = 0.046, respectively).

CONCLUSIONS

The authors recommend that spinal deformity surgeons using MIS techniques focus on correcting a patient's PI-LL mismatch to within 10° and restoring SVA to < 5 cm. Restoration of these parameters seems to impact which patients will attain the greatest degree of improvement in ODI outcomes, while the spines of patients who do the worst are not appropriately corrected and may be fused into a fixed sagittal plane deformity.

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Justin K. Scheer, Justin S. Smith, Aaron J. Clark, Virginie Lafage, Han Jo Kim, John D. Rolston, Robert Eastlack, Robert A. Hart, Themistocles S. Protopsaltis, Michael P. Kelly, Khaled Kebaish, Munish Gupta, Eric Klineberg, Richard Hostin, Christopher I. Shaffrey, Frank Schwab, Christopher P. Ames and the International Spine Study Group

OBJECT

Back and leg pain are the primary outcomes of adult spinal deformity (ASD) and predict patients' seeking of surgical management. The authors sought to characterize changes in back and leg pain after operative or nonoperative management of ASD. Outcomes were assessed according to pain severity, type of surgical procedure, Scoliosis Research Society (SRS)–Schwab spine deformity class, and patient satisfaction.

METHODS

This study retrospectively reviewed data in a prospective multicenter database of ASD patients. Inclusion criteria were the following: age > 18 years and presence of spinal deformity as defined by a scoliosis Cobb angle ≥ 20°, sagittal vertical axis length ≥ 5 cm, pelvic tilt angle ≥ 25°, or thoracic kyphosis angle ≥ 60°. Patients were grouped into nonoperated and operated subcohorts and by the type of surgical procedure, spine SRS-Schwab deformity class, preoperative pain severity, and patient satisfaction. Numerical rating scale (NRS) scores of back and leg pain, Oswestry Disability Index (ODI) scores, physical component summary (PCS) scores of the 36-Item Short Form Health Survey, minimum clinically important differences (MCIDs), and substantial clinical benefits (SCBs) were assessed.

RESULTS

Patients in whom ASD had been operatively managed were 6 times more likely to have an improvement in back pain and 3 times more likely to have an improvement in leg pain than patients in whom ASD had been nonoperatively managed. Patients whose ASD had been managed nonoperatively were more likely to have their back or leg pain remain the same or worsen. The incidence of postoperative leg pain was 37.0% at 6 weeks postoperatively and 33.3% at the 2-year follow-up (FU). At the 2-year FU, among patients with any preoperative back or leg pain, 24.3% and 37.8% were free of back and leg pain, respectively, and among patients with severe (NRS scores of 7–10) preoperative back or leg pain, 21.0% and 32.8% were free of back and leg pain, respectively. Decompression resulted in more patients having an improvement in leg pain and their pain scores reaching MCID. Although osteotomies improved back pain, they were associated with a higher incidence of leg pain. Patients whose spine had an SRS-Schwab coronal curve Type N deformity (sagittal malalignment only) were least likely to report improvements in back pain. Patients with a Type L deformity were most likely to report improved back or leg pain and to have reductions in pain severity scores reaching MCID and SCB. Patients with a Type D deformity were least likely to report improved leg pain and were more likely to experience a worsening of leg pain. Preoperative pain severity affected pain improvement over 2 years because patients who had higher preoperative pain severity experienced larger improvements, and their changes in pain severity were more likely to reach MCID/SCB than for those reporting lower preoperative pain. Reductions in back pain contributed to improvements in ODI and PCS scores and to patient satisfaction more than reductions in leg pain did.

CONCLUSIONS

The authors' results provide a valuable reference for counseling patients preoperatively about what improvements or worsening in back or leg pain they may experience after surgical intervention for ASD.

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Paul Park, Kai-Ming Fu, Robert K. Eastlack, Stacie Tran, Gregory M. Mundis Jr., Juan S. Uribe, Michael Y. Wang, Khoi D. Than, David O. Okonkwo, Adam S. Kanter, Pierce D. Nunley, Neel Anand, Richard G. Fessler, Dean Chou, Mark E. Oppenlander, Praveen V. Mummaneni and the International Spine Study Group

OBJECTIVE

It is now well accepted that spinopelvic parameters are correlated with clinical outcomes in adult spinal deformity (ASD). The purpose of this study was to determine whether obtaining optimal spinopelvic alignment was absolutely necessary to achieve a minimum clinically important difference (MCID) or substantial clinical benefit (SCB).

METHODS

A multicenter retrospective review of patients who underwent less-invasive surgery for ASD was conducted. Inclusion criteria were age ≥ 18 years and one of the following: coronal Cobb angle > 20°, sagittal vertical axis (SVA) > 5 cm, pelvic tilt (PT) > 20°, or pelvic incidence to lumbar lordosis (PI-LL) mismatch > 10°. A total of 223 patients who were treated with circumferential minimally invasive surgery or hybrid surgery and had a minimum 2-year follow-up were identified. Based on optimal spinopelvic parameters (PI-LL mismatch ± 10° and SVA < 5 cm), patients were divided into aligned (AL) or malaligned (MAL) groups. The primary clinical outcome studied was the Oswestry Disability Index (ODI) score.

RESULTS

There were 74 patients in the AL group and 149 patients in the MAL group. Age and body mass index were similar between groups. Although the baseline SVA was similar, PI-LL mismatch (9.9° vs 17.7°, p = 0.002) and PT (19° vs 24.7°, p = 0.001) significantly differed between AL and MAL groups, respectively. As expected postoperatively, the AL and MAL groups differed significantly in PI-LL mismatch (−0.9° vs 13.1°, p < 0.001), PT (14° vs 25.5°, p = 0.001), and SVA (11.8 mm vs 48.3 mm, p < 0.001), respectively. Notably, there was no difference in the proportion of AL or MAL patients in whom an MCID (52.75% vs 61.1%, p > 0.05) or SCB (40.5% vs 46.3%, p > 0.05) was achieved for ODI score, respectively. Similarly, no differences in percentage of patients obtaining an MCID or SCB for visual analog scale back and leg pain score were observed. On multivariate analysis controlling for surgical and preoperative demographic differences, achieving optimal spinopelvic parameters was not associated with achieving an MCID (OR 0.645, 95% CI 0.31–1.33) or an SCB (OR 0.644, 95% CI 0.31–1.35) for ODI score.

CONCLUSIONS

Achieving optimal spinopelvic parameters was not a predictor for achieving an MCID or SCB. Since spinopelvic parameters are correlated with clinical outcomes, the authors’ findings suggest that the presently accepted optimal spinopelvic parameters may require modification. Other factors, such as improvement in neurological symptoms and/or segmental instability, also likely impacted the clinical outcomes.

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Alan H. Daniels, Daniel B. C. Reid, Wesley M. Durand, D. Kojo Hamilton, Peter G. Passias, Han Jo Kim, Themistocles S. Protopsaltis, Virginie Lafage, Justin S. Smith, Christopher I. Shaffrey, Munish Gupta, Eric Klineberg, Frank Schwab, Douglas Burton, Shay Bess, Christopher P. Ames, Robert A. Hart and the International Spine Study Group

OBJECTIVE

Optimal patient selection for upper-thoracic (UT) versus lower-thoracic (LT) fusion during adult spinal deformity (ASD) correction is challenging. Radiographic and clinical outcomes following UT versus LT fusion remain incompletely understood. The purposes of this study were: 1) to evaluate demographic, radiographic, and surgical characteristics associated with choice of UT versus LT fusion endpoint; and 2) to evaluate differences in radiographic, clinical, and health-related quality of life (HRQOL) outcomes following UT versus LT fusion for ASD.

METHODS

Retrospective review of a prospectively collected multicenter ASD database was performed. Patients with ASD who underwent fusion from the sacrum/ilium to the LT (T9–L1) or UT (T1–6) spine were compared for demographic, radiographic, and surgical characteristics. Outcomes including proximal junctional kyphosis (PJK), reoperation, rod fracture, pseudarthrosis, overall complications, 2-year change in alignment parameters, and 2-year HRQOL metrics (Lumbar Stiffness Disability Index, Scoliosis Research Society-22r questionnaire, Oswestry Disability Index) were compared after controlling for confounding factors via multivariate analysis.

RESULTS

Three hundred three patients (169 LT, 134 UT) were evaluated. Independent predictors of UT fusion included greater thoracic kyphosis (odds ratio [OR] 0.97 per degree, p = 0.0098), greater coronal Cobb angle (OR 1.06 per degree, p < 0.0001), and performance of a 3-column osteotomy (3-CO; OR 2.39, p = 0.0351). While associated with longer operative times (ratio 1.13, p < 0.0001) and greater estimated blood loss (ratio 1.31, p = 0.0018), UT fusions resulted in greater sagittal vertical axis improvement (−59.5 vs −41.0 mm, p = 0.0035) and lower PJK rates (OR 0.49, p = 0.0457). No significant differences in postoperative HRQOL measures, reoperation, or overall complication rates were detected between groups (all p > 0.1).

CONCLUSIONS

Greater deformity and need for 3-CO increased the likelihood of UT fusion. Despite longer operative times and greater blood loss, UT fusions resulted in better sagittal correction and lower 2-year PJK rates following surgery for ASD. While continued surveillance is necessary, this information may inform patient counseling and surgical decision-making.

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Justin K. Scheer, Taemin Oh, Justin S. Smith, Christopher I. Shaffrey, Alan H. Daniels, Daniel M. Sciubba, D. Kojo Hamilton, Themistocles S. Protopsaltis, Peter G. Passias, Robert A. Hart, Douglas C. Burton, Shay Bess, Renaud Lafage, Virginie Lafage, Frank Schwab, Eric O. Klineberg, Christopher P. Ames and the International Spine Study Group

OBJECTIVE

Pseudarthrosis 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.

METHODS

A 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.

RESULTS

A 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.

CONCLUSIONS

A 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.

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Paul Park, Kai-Ming Fu, Praveen V. Mummaneni, Juan S. Uribe, Michael Y. Wang, Stacie Tran, Adam S. Kanter, Pierce D. Nunley, David O. Okonkwo, Christopher I. Shaffrey, Gregory M. Mundis Jr., Dean Chou, Robert Eastlack, Neel Anand, Khoi D. Than, Joseph M. Zavatsky, Richard G. Fessler and the International Spine Study Group

OBJECTIVE

Achieving appropriate spinopelvic alignment in deformity surgery has been correlated with improvement in pain and disability. Minimally invasive surgery (MIS) techniques have been used to treat adult spinal deformity (ASD); however, there is concern for inadequate sagittal plane correction. Because age can influence the degree of sagittal correction required, the purpose of this study was to analyze whether obtaining optimal spinopelvic alignment is required in the elderly to obtain clinical improvement.

METHODS

A multicenter database of ASD patients was queried. Inclusion criteria were age ≥ 18 years; an MIS component as part of the index procedure; at least one of the following: pelvic tilt (PT) > 20°, sagittal vertical axis (SVA) > 50 mm, pelvic incidence to lumbar lordosis (PI-LL) mismatch > 10°, or coronal curve > 20°; and minimum follow-up of 2 years. Patients were stratified into younger (< 65 years) and older (≥ 65 years) cohorts. Within each cohort, patients were categorized into aligned (AL) or mal-aligned (MAL) subgroups based on postoperative radiographic measurements. Mal-alignment was defined as a PI-LL > 10° or SVA > 50 mm. Pre- and postoperative radiographic and clinical outcomes were compared.

RESULTS

Of the 185 patients, 107 were in the younger cohort and 78 in the older cohort. Based on postoperative radiographs, 36 (33.6%) of the younger patients were in the AL subgroup and 71 (66.4%) were in the MAL subgroup. The older patients were divided into 2 subgroups based on alignment; there were 26 (33.3%) patients in the AL and 52 (66.7%) in the MAL subgroups. Overall, patients within both younger and older cohorts significantly improved with regard to postoperative visual analog scale (VAS) scores for back and leg pain and Oswestry Disability Index (ODI) scores. In the younger cohort, there were no significant differences in postoperative VAS back and leg pain scores between the AL and MAL subgroups. However, the postoperative ODI score of 37.9 in the MAL subgroup was significantly worse than the ODI score of 28.5 in the AL subgroup (p = 0.019). In the older cohort, there were no significant differences in postoperative VAS back and leg pain score or ODI between the AL and MAL subgroups.

CONCLUSIONS

MIS techniques did not achieve optimal spinopelvic alignment in most cases. However, age appears to impact the degree of sagittal correction required. In older patients, optimal spinopelvic alignment thresholds did not need to be achieved to obtain similar symptomatic improvement. Conversely, in younger patients stricter adherence to optimal spinopelvic alignment thresholds may be needed.

https://thejns.org/doi/abs/10.3171/2018.4.SPINE171153

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Justin K. Scheer, Virginie Lafage, Justin S. Smith, Vedat Deviren, Richard Hostin, Ian M. McCarthy, Gregory M. Mundis, Douglas C. Burton, Eric Klineberg, Munish C. Gupta, Khaled M. Kebaish, Christopher I. Shaffrey, Shay Bess, Frank Schwab, Christopher P. Ames and the International Spine Study Group (ISSG)

Object

Spinal osteotomies for adult spinal deformity correction may include resection of all 3 spinal columns (pedicle subtraction osteotomy [PSO] and vertebral column resection [VCR]). The relationship between patient age and health-related quality of life (HRQOL) outcomes for patients undergoing major spinal deformity correction via PSO or VCR has not been well characterized. The goal of this study was to characterize that relationship.

Methods

This study was a retrospective review of 374 patients who had undergone a 3-column osteotomy (299 PSOs and 75 VCRs) and were part of a prospectively collected, multicenter adult spinal deformity database. The consecutively enrolled patients were drawn from 11 sites across the United States. Health-related QOL outcomes, according to the visual analog scale (VAS), Oswestry Disability Index (ODI), 36-Item Short-Form Health Survey (SF-36, physical component score [PCS] and mental component score), and Scoliosis Research Society-22 questionnaire (SRS), were evaluated preoperatively and 1 and 2 years postoperatively. Differences and correlations between patient age and HRQOL outcomes were investigated. Age groupings included young (age ≤ 45 years), middle aged (age 46–64 years), and elderly (age ≥ 65 years).

Results

In patients who had undergone PSO, age significantly correlated (Spearman's correlation coefficient) with the 2-year ODI (ρ = 0.24, p = 0.0450), 2-year SRS function score (ρ = 0.30, p = 0.0123), and 2-year SRS total score (ρ = 0.30, p = 0.0133). Among all patients (PSO+VCR), the preoperative PCS and ODI in the young group were significantly higher and lower, respectively, than those in the elderly. Among the PSO patients, the elderly group had much greater improvement than the young group in the 1- and 2-year PCS, 2-year ODI, and 2-year SRS function and total scores. Among the VCR patients, the young age group had much greater improvement than the elderly in the 1-year SRS pain score, 1-year PCS, 2-year PCS, and 2-year ODI. There was no significant difference among all the age groups as regards the likelihood of reaching a minimum clinically important difference (MCID) within each of the HRQOL outcomes (p > 0.05 for all). Among the PSO patients, the elderly group was significantly more likely than the young to reach an MCID for the 1-year PCS (61% vs 21%, p = 0.0077) and the 2-year PCS (67% vs 17%, p = 0.0054), SRS pain score (57% vs 20%, p = 0.0457), and SRS function score (62% vs 20%, p = 0.0250). Among the VCR patients, the young group was significantly more likely than the elderly patients to reach an MCID for the 1-year (100% vs 20%, p = 0.0036) and 2-year (100% vs 0%, p = 0.0027) PCS scores and 1-year (60% vs 0%, p = 0.0173) and 2-year (70% vs 0%, p = 0.0433) SRS pain scores.

Conclusions

The PSO and VCR are not equivalent surgeries in terms of HRQOL outcomes and patient age. Among patients who underwent PSO, the elderly group started with more preoperative disability than the younger patients but had greater improvements in HRQOL outcomes and was more likely to reach an MCID at 1 and 2 years after treatment. Among those who underwent VCR, all had similar preoperative disabilities, but the younger patients had greater improvements in HRQOL outcomes and were more likely to reach an MCID at 1 and 2 years after treatment.

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Praveen V. Mummaneni, Paul Park, Christopher I. Shaffrey, Michael Y. Wang, Juan S. Uribe, Richard G. Fessler, Dean Chou, Adam S. Kanter, David O. Okonkwo, Gregory M. Mundis Jr., Robert K. Eastlack, Pierce D. Nunley, Neel Anand, Michael S. Virk, Lawrence G. Lenke, Khoi D. Than, Leslie C. Robinson, Kai-Ming Fu and the International Spine Study Group (ISSG)

OBJECTIVE

Minimally invasive surgery (MIS) can be used as an alternative or adjunct to traditional open techniques for the treatment of patients with adult spinal deformity. Recent advances in MIS techniques, including advanced anterior approaches, have increased the range of candidates for MIS deformity surgery. The minimally invasive spinal deformity surgery (MISDEF2) algorithm was created to provide an updated framework for decision-making when considering MIS techniques in correction of adult spinal deformity.

METHODS

A modified algorithm was developed that incorporates a patient’s preoperative radiographic parameters and leads to one of 4 general plans ranging from basic to advanced MIS techniques to open deformity surgery with osteotomies. The authors surveyed 14 fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 24 cases to establish interobserver reliability. They then re-surveyed the same surgeons 2 months later with the same cases presented in a different sequence to establish intraobserver reliability. Responses were collected and analyzed. Correlation values were determined using SPSS software.

RESULTS

Over a 3-month period, 14 fellowship-trained deformity surgeons completed the surveys. Responses for MISDEF2 algorithm case review demonstrated an interobserver kappa of 0.85 for the first round of surveys and an interobserver kappa of 0.82 for the second round of surveys, consistent with substantial agreement. In at least 7 cases, there was perfect agreement between the reviewing surgeons. The mean intraobserver kappa for the 2 surveys was 0.8.

CONCLUSIONS

The MISDEF2 algorithm was found to have substantial inter- and intraobserver agreement. The MISDEF2 algorithm incorporates recent advances in MIS surgery. The use of the MISDEF2 algorithm provides reliable guidance for surgeons who are considering either an MIS or an open approach for the treatment of patients with adult spinal deformity.