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Papers by Adam Kanter

Research paper thumbnail of The impact of age on surgical goals for spinopelvic alignment in minimally invasive surgery for adult spinal deformity

Journal of neurosurgery. Spine, Jan 10, 2018

OBJECTIVE Achieving appropriate spinopelvic alignment in deformity surgery has been correlated wi... more 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,...

Research paper thumbnail of Home versus Rehabilitation: Factors that Influence Disposition after Minimally Invasive Surgery in Adult Spinal Deformity Surgery

World neurosurgery, Jan 10, 2018

MIS correction for ASD may reduce the need the need for postoperative skilled nursing (SNF) or re... more MIS correction for ASD may reduce the need the need for postoperative skilled nursing (SNF) or rehabilitation facility placement following surgery. The likelihood of requiring placement in a facility, rather than home disposition, may be influenced by a variety of factors. Additionally, the association of discharge location on outcomes and complication rates has not been elucidated in these patients. In this study, we aimed to define factors predicting disposition to SNF/rehab, and the rates of complications occurring in patients sent home vs. a facility. A retrospective review of a multi-center ASD database, which included patients who underwent surgery between 2009-2014. >18 yrs old, MIS as part of index surgery, location of discharge, and at least one of the following: PT>20, SVA>5cm, PI-LL>10, or lumbar scoliosis>20. Patients with 2 yr follow-up were included. Preoperative demographic and radiographic data, postop (<30 day) complications and HRQL were analyzed....

Research paper thumbnail of Curve Laterality for Lateral Lumbar Interbody Fusion in Adult Scoliosis Surgery: The Concave Versus Convex Controversy

Neurosurgery, Jan 18, 2018

Minimally invasive lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degene... more Minimally invasive lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degenerative scoliosis (ADS) surgery. LLIF approaches performed from the concavity or convexity have inherent approach-related risks and benefits. To analyze LLIF approach-related complications and radiographic and clinical outcomes in patients with ADS. A multicenter retrospective review of a minimally invasive adult spinal deformity database was queried with a minimum of 2-yr follow-up. Patients were divided into 2 groups as determined by the side of the curve from which the LLIF was performed: concave or convex. No differences between groups were noted in demographic, and preoperative or postoperative radiographic parameters (all P > .05). There were 8 total complications in the convex group (34.8%) and 21 complications in the concave group (52.5%; P = .17). A subgroup analysis was performed in 49 patients in whom L4-5 was in the primary curve and not in the fractional curve. In this sub...

Research paper thumbnail of Complication rates associated with open versus percutaneous pedicle screw instrumentation among patients undergoing minimally invasive interbody fusion for adult spinal deformity

Neurosurgical focus, 2017

OBJECTIVE High-quality studies that compare outcomes of open and minimally invasively placed pedi... more OBJECTIVE High-quality studies that compare outcomes of open and minimally invasively placed pedicle screws for adult spinal deformity are needed. Therefore, the authors compared differences in complications from a circumferential minimally invasive spine (MIS) surgery and those from a hybrid surgery. METHODS A retrospective review of a multicenter database of patients with spinal deformity who were treated with an MIS surgery was performed. Database inclusion criteria included an age of ≥ 18 years and at least 1 of the following: a coronal Cobb angle of > 20°, a sagittal vertical axis of > 5 cm, a pelvic incidence-lumbar lordosis angle of > 10°, and/or a pelvic tilt of > 20°. Patients were propensity matched according to the levels instrumented. RESULTS In this database, a complete data set was available for 165 patients, and after those who underwent 3-column osteotomy were excluded, 137 patients were available for analysis; 76 patients remained after propensity matchi...

Research paper thumbnail of Impact of case type, length of stay, institution type, and comorbidities on Medicare diagnosis-related group reimbursement for adult spinal deformity surgery

Neurosurgical focus, 2017

OBJECTIVE The aim of this study was to educate medical professionals about potential financial im... more OBJECTIVE The aim of this study was to educate medical professionals about potential financial impacts of improper diagnosis-related group (DRG) coding in adult spinal deformity (ASD) surgery. METHODS Medicare's Inpatient Prospective Payment System PC Pricer database was used to collect 2015 reimbursement data for ASD procedures from 12 hospitals. Case type, hospital type/location, number of operative levels, proper coding, length of stay, and complications/comorbidities (CCs) were analyzed for effects on reimbursement. DRGs were used to categorize cases into 3 types: 1) anterior or posterior only fusion, 2) anterior fusion with posterior percutaneous fixation with no dorsal fusion, and 3) combined anterior and posterior fixation and fusion. RESULTS Pooling institutions, cases were reimbursed the same for single-level and multilevel ASD surgery. Longer stay, from 3 to 8 days, resulted in an additional 1400perstay.Posteriorfusionwasanadditional1400 per stay. Posterior fusion was an additional 1400perstay.Posteriorfusionwasanadditional6588, while CCs increased ...

Research paper thumbnail of Is There a Patient Profile That Characterizes a Patient With Adult Spinal Deformity as a Candidate for Minimally Invasive Surgery?

Global spine journal, 2017

Retrospective review. The goal of this study was to evaluate the baseline characteristics of pati... more Retrospective review. The goal of this study was to evaluate the baseline characteristics of patients chosen to undergo traditional open versus minimally invasive surgery (MIS) for adult spinal deformity (ASD). A multicenter review of 2 databases including ASD patients treated with surgery. Inclusion criteria were age >45 years, Cobb angle minimum of 20°, and minimum 2-year follow-up. Preoperative radiographic parameters and disability outcome measures were reviewed. A total of 350 patients were identified: 173 OPEN patients and 177 MIS. OPEN patients were significantly younger than MIS patients (61.5 years vs 63.74 years, P = .013). The OPEN group had significantly more females (87% vs 76%, P = .006), but both groups had similar body mass index. Preoperative lumbar Cobb was significantly higher for the OPEN group (34.2°) than for the MIS group (26.0°, P < .001). The mean preoperative Oswestry Disability Index was significantly higher in the MIS group (44.8 in OPEN patients an...

Research paper thumbnail of Patients with High Pelvic Tilt Achieve the Same Clinical Success as Those with Low Pelvic Tilt After Minimally Invasive Adult Deformity Surgery

Neurosurgery, 2017

BACKGROUND Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mi... more BACKGROUND Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mitigate sagittal imbalance. The association between preop PT and postop clinical and radiographic outcomes has not been well studied in patients undergoing minimally invasive adult deformity surgery. OBJECTIVE To evaluate clinical and radiographic outcomes in adult spinal deformity patients with high and low preoperative PT treated surgically using less invasive techniques. METHODS Retrospective case-control, institutional review board-approved study. A multicenter, minimally invasive surgery spinal deformity patient database was queried for 2-yr follow-up with complete radiographic and health-related quality of life (HRQOL) data. Hybrid surgery patients were excluded. Inclusion criteria were as follows: age > 18 and either coronal Cobb angle > 20, sagittal vertical axis > 5 cm, pelvic incidence-lumbar lordosis (PI-LL) > 10 or PT > 20. Patients were stratified by preop PT a...

Research paper thumbnail of A Novel Tool for Deformity Surgery Planning: Determining the Magnitude of Lordotic Correction Required to Achieve a Desired Sagittal Vertical Axis

World neurosurgery, Jan 24, 2017

We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordos... more We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordosis (PI-LL) correction necessary to achieve a desired change in sagittal vertical axis (SVA). Retrospective review of a prospectively maintained multicenter adult spinal deformity database collected by the International Spine Study Group between 2009 and 2014. The independent variable of interest was the degree of correction achieved in the PI-LL mismatch at 6-weeks post-surgery. Primary outcome was the change in global sagittal alignment at 6 weeks and 1 year after surgery. We used a linear mixed-effects model to determine the extent to which corrections in the PI-LL relationship affected post-operative changes in SVA. A total of 1053 adult patients were identified. Of these, 590 were managed surgically. 87 surgically managed patients were excluded due to incomplete or missing PI-LL measurements on follow-up; the remaining 503 of these patients were selected for inclusion. For each degre...

Research paper thumbnail of Rare Complications of Cervical Spine Surgery: Horner's Syndrome

Global spine journal, 2017

A multicenter retrospective case series. Horner's syndrome is a known complication of anterio... more A multicenter retrospective case series. Horner's syndrome is a known complication of anterior cervical spinal surgery, but it is rarely encountered in clinical practice. To better understand the incidence, risks, and neurologic outcomes associated with Horner's syndrome, a multicenter study was performed to review a large collective experience with this rare complication. We conducted a retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. Paired t test was used to analyze changes in clinical outcomes at follow-up compared to preoperative status. In total, 8887 patients who underwent anterior cervical spine surgery at the participating i...

Research paper thumbnail of A Multicenter Study of the Presentation, Treatment, and Outcomes of Cervical Dural Tears

Global spine journal, 2017

Retrospective multicenter case series study. Because cervical dural tears are rare, most surgeons... more Retrospective multicenter case series study. Because cervical dural tears are rare, most surgeons have limited experience with this complication. A multicenter study was performed to better understand the presentation, treatment, and outcomes following cervical dural tears. Multiple surgeons from 23 institutions retrospectively identified 21 rare complications that occurred between 2005 and 2011, including unintentional cervical dural tears. Demographic data and surgical history were obtained. Clinical outcomes following surgery were assessed, and any reoperations were recorded. Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA), Nurick classification (NuC), and Short-Form 36 (SF36) scores were recorded at baseline and final follow-up at certain centers. All data were collected, collated, and analyzed by a private research organization. There were 109 cases of cervical dural tears among 18 463 surgeries performed. In 101 cases (93%) there was no clinical s...

Research paper thumbnail of A Multicenter Review of Superior Laryngeal Nerve Injury Following Anterior Cervical Spine Surgery

Global spine journal, 2017

A retrospective multicenter case-series study; case report and review of the literature. The anat... more A retrospective multicenter case-series study; case report and review of the literature. The anatomy and function of the superior laryngeal nerve (SLN) are well described; however, the consequences of SLN injury remain variable and poorly defined. The prevalence of SLN injury as a consequence of cervical spine surgery is difficult to discern as its clinical manifestations are often inconstant and frequently of a subclinical degree. A multicenter study was performed to better delineate the risk factors, prevalence, and outcomes of SLN injury. A retrospective multicenter case-series study involving 21 high-volume surgical centers from the AO Spine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. A retrospective review of the neurosurgical liter...

Research paper thumbnail of Does the Use of Minimally Invasive Pedicle Screw Fixation Lower the Rate of PJK and Reoperation for PJF?

Research paper thumbnail of Comparison of 3 Minimally Invasive Surgery (MIS) Strategies to Treat Adult Spinal Deformity (ASD)

Research paper thumbnail of Reoperation rates in minimally invasive, hybrid and open surgical treatment for adult spinal deformity with minimum 2-year follow-up

European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, Aug 24, 2016

Minimally invasive surgical (MIS) techniques are gaining popularity in the treatment of adult spi... more Minimally invasive surgical (MIS) techniques are gaining popularity in the treatment of adult spinal deformity (ASD). The premise is that MIS techniques will lead to equivalent outcomes and a reduction in perioperative complications when compared with open techniques. Potential issues with MIS techniques are a limited capacity to correct lumbar lordosis, unknown long-term efficacy, and the potential need for revision surgery. This study compares reoperation rates and reasons for reoperation following MIS, hybrid, and open surgery for ASD through multicenter database analysis. We retrospectively analyzed a prospective multicenter ASD database comparing open and MIS correction techniques. Inclusion criteria were: age > 18 years with minimum 20° coronal lumbar Cobb angle, a minimum of three levels fused, and minimum 2-year follow-up. Patients were propensity matched for preoperative sagittal vertebral axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and number of levels fused. ...

Research paper thumbnail of Comparison of Complications and Clinical and Radiographic Outcomes Between Nonobese and Obese Patients with Adult Spinal Deformity Undergoing Minimally Invasive Surgery

World Neurosurgery, 2016

Obesity can be associated with increased complications and potentially worse outcomes. We aimed t... more Obesity can be associated with increased complications and potentially worse outcomes. We aimed to evaluate the impact of obesity on complications and outcomes in patients with adult spinal deformity (ASD) who underwent minimally invasive surgery (MIS). Multicenter database of patients with ASD treated via MIS was queried. Of 190 patients in the database, 77 fit the inclusion criteria of 3 or more spinal levels treated minimally invasively. Patients were divided by body mass index (BMI) &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 30 (non-obese; n = 59), and BMI ≥ 30 (obese; n = 18). Mean BMI was 24.6 non-obese, and 35.0 obese (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). There were mean 3.8 interbody fusions non-obese, and 4.7 obese (p = 0.065). Levels treated posteriorly averaged 5.8 non-obese, and 5.9 obese (p = 0.502). Mean follow-up was 34.4 months non-obese, and 35.3 months obese (p = 0.976). Baseline radiographic parameters were similar between groups. Postoperatively, SVA averaged 83.9 mm obese and 20.4 mm non-obese (p = 0.002). Postoperative lumbar lordosis-pelvic incidence mismatch averaged 17.9° obese and 9.9° non-obese (p = 0.028). Both groups had improvement in ODI scores with no difference in postoperative ODI scores between groups (p = 0.090). Similarly, both groups had decreased VAS scores for back and leg pain with no difference between groups postoperatively. Twenty (33.9%) non-obese patients versus 7 (38.9%) obese patients had complications (p = 0.452). Our results suggest that obesity does not negatively impact complication rate or clinical outcomes in patients with ASD treated via MIS approaches.

Research paper thumbnail of Can a Minimal Clinically Important Difference Be Achieved in Elderly Patients with Adult Spinal Deformity Who Undergo Minimally Invasive Spinal Surgery?

World Neurosurgery, 2016

Older age has been considered a relative contraindication to complex spinal procedures. Minimally... more Older age has been considered a relative contraindication to complex spinal procedures. Minimally invasive surgery (MIS) techniques to treat patients with adult spinal deformity (ASD) have emerged with the potential benefit of decreased approach-related morbidity. To determine whether a minimal clinically important difference (MCID) could be achieved in patients aged ≥65 years with ASD who underwent MIS. Multicenter database of patients who underwent MIS for ASD was queried. Outcome metrics assessed were ODI and VAS scores for back and leg pain. Based on published reports, MCID was defined as a positive change of 12.8 ODI, 1.2 VAS back pain, and 1.6 VAS leg pain. Forty-two patients were identified. Mean age was 70.3 years, 31 (73.8%) were female. Preoperatively, mean CC, PT, pelvic incidence to lumbar lordosis (PI-LL) mismatch, and SVA were 35°, 24.6°, 14.2°, and 4.7 cm, respectively. Postoperatively, mean CC, PT, PI-LL, and SVA were 18°, 25.4°, 11.9°, and 4.9 cm, respectively. Mean 5.0 levels were treated posteriorly, and mean 4.0 interbody fusions were performed. Mean ODI improved from 47.1 to 25.1. Mean VAS back and leg pain scores improved from 6.8 and 5.9 to 2.7 and 2.7, respectively. Mean follow-up was 32.1 months. For ODI, 64.3% of patients achieved MCID. For VAS back and leg pain, 82.9% and 72.2%, respectively, reached MCID. MCID represents the threshold where patients feel a meaningful clinical improvement has occurred. Our study results suggest that the majority of elderly patients with modest ASD can achieve MCID with MIS.

Research paper thumbnail of Clinical and Radiographic Parameters Associated with Best versus Worst Clinical Outcomes in Minimally Invasive Deformity Surgery

The Spine Journal, 2015

Background. Conventional cardiac risk scores may not be completely accurate in predicting acute e... more Background. Conventional cardiac risk scores may not be completely accurate in predicting acute events because they only include factors associated with atherosclerosis, considered as the fundamental precursor of cardiovascular disease. In UK in 2006-2008 (Whitehall II study) we tested the ability of several risk scores to identify individuals with cardiac cell damage and assessed to what extent their estimates were mediated by the presence of atherosclerosis. Methods. 430 disease-free, low-risk participants were tested for high-sensitivity cardiac troponin-T (HS-CTnT) and for coronary calcification using electron-beam, dual-source, computed tomography (CAC). We analysed the data cross-sectionally using ROC curves and mediation tests. Results. When the risk scores were ranked according to the magnitude of ROC areas for HS-CTnT prediction, a score based only on age and gender came first (ROC area = 0.79), followed by Q-Risk2 (0.76), Framingham (0.70), Joint-British-Societies (0.69) and Assign (0.68). However, when the scores were ranked according to the extent of mediation by CAC (proportion of association mediated), their order was essentially reversed (age&gender = 6.8%, Q-Risk2 = 9.7%, Framingham = 16.9%, JBS = 17.8%, Assign = 17.7%). Therefore, the more accurate a score is in predicting detectable HS-CTnT, the less it is mediated by CAC; i.e. the more able a score is in capturing atherosclerosis the less it is able to predict cardiac damage. The P for trend was 0.009. Conclusions. The dynamics through which cardiac cell damage is caused cannot be explained by 'classic' heart disease risk factors alone. Further research is needed to identify precursors of heart disease other than atherosclerosis.

Research paper thumbnail of A Critical Analysis of Sagittal Plane Deformity Correction with Minimally Invasive Adult Spinal Deformity Surgery: A Two-Year Follow-Up Study

The Spine Journal, 2015

Introduction: Sagittal plane realignment is important to achieve desirable clinical outcomes afte... more Introduction: Sagittal plane realignment is important to achieve desirable clinical outcomes after adult spinal deformity (ASD) surgery. This study evaluates the impact of minimally invasive (MIS) techniques on sagittal plane alignment and clinical outcomes in ASD patients. Methods: A retrospective, multi-center review of ASD patients (age >18 years, and with one of the following: coronal Cobb >20 , sagittal vertical axis [SVA] O5 cm, and/or pelvic tilt O25), MIS surgery, and four or more levels instrumented. Patients were stratified by baseline SRS-Schwab global alignment modifier (GAM) into three groups: 0 (SVA !4 cm), þ (SVA 4e9.5 cm), or þþ (SVA O9.5 cm). Radiographic and clinical outcomes measures were analyzed with a minimum of 2-year follow-up.

Research paper thumbnail of Thoracolumbar spinal deformity

Journal of neurosurgery. Spine, 2009

Research paper thumbnail of Comparison of two minimally invasive surgery strategies to treat adult spinal deformity

Journal of neurosurgery. Spine, Jan 30, 2015

OBJECT Minimally invasive surgery (MIS) techniques are becoming a more common means of treating a... more OBJECT Minimally invasive surgery (MIS) techniques are becoming a more common means of treating adult spinal deformity (ASD). The aim of this study was to compare the hybrid (HYB) surgical approach, involving minimally invasive lateral interbody fusion with open posterior instrumented fusion, to the circumferential MIS (cMIS) approach to treat ASD. METHODS The authors performed a retrospective, multicenter study utilizing data collected in 105 patients with ASD who were treated via MIS techniques. Criteria for inclusion were age older than 45 years, coronal Cobb angle greater than 20°, and a minimum of 1 year of follow-up. Patients were stratified into 2 groups: HYB (n = 62) and cMIS (n = 43). RESULTS The mean age was 60.7 years in the HYB group and 61.0 years in the cMIS group (p = 0.910). A mean of 3.6 interbody fusions were performed in the HYB group compared with a mean of 4.0 interbody fusions in the cMIS group (p = 0.086). Posterior fusion involved a mean of 6.9 levels in the ...

Research paper thumbnail of The impact of age on surgical goals for spinopelvic alignment in minimally invasive surgery for adult spinal deformity

Journal of neurosurgery. Spine, Jan 10, 2018

OBJECTIVE Achieving appropriate spinopelvic alignment in deformity surgery has been correlated wi... more 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,...

Research paper thumbnail of Home versus Rehabilitation: Factors that Influence Disposition after Minimally Invasive Surgery in Adult Spinal Deformity Surgery

World neurosurgery, Jan 10, 2018

MIS correction for ASD may reduce the need the need for postoperative skilled nursing (SNF) or re... more MIS correction for ASD may reduce the need the need for postoperative skilled nursing (SNF) or rehabilitation facility placement following surgery. The likelihood of requiring placement in a facility, rather than home disposition, may be influenced by a variety of factors. Additionally, the association of discharge location on outcomes and complication rates has not been elucidated in these patients. In this study, we aimed to define factors predicting disposition to SNF/rehab, and the rates of complications occurring in patients sent home vs. a facility. A retrospective review of a multi-center ASD database, which included patients who underwent surgery between 2009-2014. >18 yrs old, MIS as part of index surgery, location of discharge, and at least one of the following: PT>20, SVA>5cm, PI-LL>10, or lumbar scoliosis>20. Patients with 2 yr follow-up were included. Preoperative demographic and radiographic data, postop (<30 day) complications and HRQL were analyzed....

Research paper thumbnail of Curve Laterality for Lateral Lumbar Interbody Fusion in Adult Scoliosis Surgery: The Concave Versus Convex Controversy

Neurosurgery, Jan 18, 2018

Minimally invasive lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degene... more Minimally invasive lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degenerative scoliosis (ADS) surgery. LLIF approaches performed from the concavity or convexity have inherent approach-related risks and benefits. To analyze LLIF approach-related complications and radiographic and clinical outcomes in patients with ADS. A multicenter retrospective review of a minimally invasive adult spinal deformity database was queried with a minimum of 2-yr follow-up. Patients were divided into 2 groups as determined by the side of the curve from which the LLIF was performed: concave or convex. No differences between groups were noted in demographic, and preoperative or postoperative radiographic parameters (all P > .05). There were 8 total complications in the convex group (34.8%) and 21 complications in the concave group (52.5%; P = .17). A subgroup analysis was performed in 49 patients in whom L4-5 was in the primary curve and not in the fractional curve. In this sub...

Research paper thumbnail of Complication rates associated with open versus percutaneous pedicle screw instrumentation among patients undergoing minimally invasive interbody fusion for adult spinal deformity

Neurosurgical focus, 2017

OBJECTIVE High-quality studies that compare outcomes of open and minimally invasively placed pedi... more OBJECTIVE High-quality studies that compare outcomes of open and minimally invasively placed pedicle screws for adult spinal deformity are needed. Therefore, the authors compared differences in complications from a circumferential minimally invasive spine (MIS) surgery and those from a hybrid surgery. METHODS A retrospective review of a multicenter database of patients with spinal deformity who were treated with an MIS surgery was performed. Database inclusion criteria included an age of ≥ 18 years and at least 1 of the following: a coronal Cobb angle of > 20°, a sagittal vertical axis of > 5 cm, a pelvic incidence-lumbar lordosis angle of > 10°, and/or a pelvic tilt of > 20°. Patients were propensity matched according to the levels instrumented. RESULTS In this database, a complete data set was available for 165 patients, and after those who underwent 3-column osteotomy were excluded, 137 patients were available for analysis; 76 patients remained after propensity matchi...

Research paper thumbnail of Impact of case type, length of stay, institution type, and comorbidities on Medicare diagnosis-related group reimbursement for adult spinal deformity surgery

Neurosurgical focus, 2017

OBJECTIVE The aim of this study was to educate medical professionals about potential financial im... more OBJECTIVE The aim of this study was to educate medical professionals about potential financial impacts of improper diagnosis-related group (DRG) coding in adult spinal deformity (ASD) surgery. METHODS Medicare's Inpatient Prospective Payment System PC Pricer database was used to collect 2015 reimbursement data for ASD procedures from 12 hospitals. Case type, hospital type/location, number of operative levels, proper coding, length of stay, and complications/comorbidities (CCs) were analyzed for effects on reimbursement. DRGs were used to categorize cases into 3 types: 1) anterior or posterior only fusion, 2) anterior fusion with posterior percutaneous fixation with no dorsal fusion, and 3) combined anterior and posterior fixation and fusion. RESULTS Pooling institutions, cases were reimbursed the same for single-level and multilevel ASD surgery. Longer stay, from 3 to 8 days, resulted in an additional 1400perstay.Posteriorfusionwasanadditional1400 per stay. Posterior fusion was an additional 1400perstay.Posteriorfusionwasanadditional6588, while CCs increased ...

Research paper thumbnail of Is There a Patient Profile That Characterizes a Patient With Adult Spinal Deformity as a Candidate for Minimally Invasive Surgery?

Global spine journal, 2017

Retrospective review. The goal of this study was to evaluate the baseline characteristics of pati... more Retrospective review. The goal of this study was to evaluate the baseline characteristics of patients chosen to undergo traditional open versus minimally invasive surgery (MIS) for adult spinal deformity (ASD). A multicenter review of 2 databases including ASD patients treated with surgery. Inclusion criteria were age >45 years, Cobb angle minimum of 20°, and minimum 2-year follow-up. Preoperative radiographic parameters and disability outcome measures were reviewed. A total of 350 patients were identified: 173 OPEN patients and 177 MIS. OPEN patients were significantly younger than MIS patients (61.5 years vs 63.74 years, P = .013). The OPEN group had significantly more females (87% vs 76%, P = .006), but both groups had similar body mass index. Preoperative lumbar Cobb was significantly higher for the OPEN group (34.2°) than for the MIS group (26.0°, P < .001). The mean preoperative Oswestry Disability Index was significantly higher in the MIS group (44.8 in OPEN patients an...

Research paper thumbnail of Patients with High Pelvic Tilt Achieve the Same Clinical Success as Those with Low Pelvic Tilt After Minimally Invasive Adult Deformity Surgery

Neurosurgery, 2017

BACKGROUND Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mi... more BACKGROUND Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mitigate sagittal imbalance. The association between preop PT and postop clinical and radiographic outcomes has not been well studied in patients undergoing minimally invasive adult deformity surgery. OBJECTIVE To evaluate clinical and radiographic outcomes in adult spinal deformity patients with high and low preoperative PT treated surgically using less invasive techniques. METHODS Retrospective case-control, institutional review board-approved study. A multicenter, minimally invasive surgery spinal deformity patient database was queried for 2-yr follow-up with complete radiographic and health-related quality of life (HRQOL) data. Hybrid surgery patients were excluded. Inclusion criteria were as follows: age > 18 and either coronal Cobb angle > 20, sagittal vertical axis > 5 cm, pelvic incidence-lumbar lordosis (PI-LL) > 10 or PT > 20. Patients were stratified by preop PT a...

Research paper thumbnail of A Novel Tool for Deformity Surgery Planning: Determining the Magnitude of Lordotic Correction Required to Achieve a Desired Sagittal Vertical Axis

World neurosurgery, Jan 24, 2017

We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordos... more We sought to create a model capable of predicting the magnitude of pelvic incidence-lumbar lordosis (PI-LL) correction necessary to achieve a desired change in sagittal vertical axis (SVA). Retrospective review of a prospectively maintained multicenter adult spinal deformity database collected by the International Spine Study Group between 2009 and 2014. The independent variable of interest was the degree of correction achieved in the PI-LL mismatch at 6-weeks post-surgery. Primary outcome was the change in global sagittal alignment at 6 weeks and 1 year after surgery. We used a linear mixed-effects model to determine the extent to which corrections in the PI-LL relationship affected post-operative changes in SVA. A total of 1053 adult patients were identified. Of these, 590 were managed surgically. 87 surgically managed patients were excluded due to incomplete or missing PI-LL measurements on follow-up; the remaining 503 of these patients were selected for inclusion. For each degre...

Research paper thumbnail of Rare Complications of Cervical Spine Surgery: Horner's Syndrome

Global spine journal, 2017

A multicenter retrospective case series. Horner's syndrome is a known complication of anterio... more A multicenter retrospective case series. Horner's syndrome is a known complication of anterior cervical spinal surgery, but it is rarely encountered in clinical practice. To better understand the incidence, risks, and neurologic outcomes associated with Horner's syndrome, a multicenter study was performed to review a large collective experience with this rare complication. We conducted a retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. Paired t test was used to analyze changes in clinical outcomes at follow-up compared to preoperative status. In total, 8887 patients who underwent anterior cervical spine surgery at the participating i...

Research paper thumbnail of A Multicenter Study of the Presentation, Treatment, and Outcomes of Cervical Dural Tears

Global spine journal, 2017

Retrospective multicenter case series study. Because cervical dural tears are rare, most surgeons... more Retrospective multicenter case series study. Because cervical dural tears are rare, most surgeons have limited experience with this complication. A multicenter study was performed to better understand the presentation, treatment, and outcomes following cervical dural tears. Multiple surgeons from 23 institutions retrospectively identified 21 rare complications that occurred between 2005 and 2011, including unintentional cervical dural tears. Demographic data and surgical history were obtained. Clinical outcomes following surgery were assessed, and any reoperations were recorded. Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA), Nurick classification (NuC), and Short-Form 36 (SF36) scores were recorded at baseline and final follow-up at certain centers. All data were collected, collated, and analyzed by a private research organization. There were 109 cases of cervical dural tears among 18 463 surgeries performed. In 101 cases (93%) there was no clinical s...

Research paper thumbnail of A Multicenter Review of Superior Laryngeal Nerve Injury Following Anterior Cervical Spine Surgery

Global spine journal, 2017

A retrospective multicenter case-series study; case report and review of the literature. The anat... more A retrospective multicenter case-series study; case report and review of the literature. The anatomy and function of the superior laryngeal nerve (SLN) are well described; however, the consequences of SLN injury remain variable and poorly defined. The prevalence of SLN injury as a consequence of cervical spine surgery is difficult to discern as its clinical manifestations are often inconstant and frequently of a subclinical degree. A multicenter study was performed to better delineate the risk factors, prevalence, and outcomes of SLN injury. A retrospective multicenter case-series study involving 21 high-volume surgical centers from the AO Spine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. A retrospective review of the neurosurgical liter...

Research paper thumbnail of Does the Use of Minimally Invasive Pedicle Screw Fixation Lower the Rate of PJK and Reoperation for PJF?

Research paper thumbnail of Comparison of 3 Minimally Invasive Surgery (MIS) Strategies to Treat Adult Spinal Deformity (ASD)

Research paper thumbnail of Reoperation rates in minimally invasive, hybrid and open surgical treatment for adult spinal deformity with minimum 2-year follow-up

European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society, Aug 24, 2016

Minimally invasive surgical (MIS) techniques are gaining popularity in the treatment of adult spi... more Minimally invasive surgical (MIS) techniques are gaining popularity in the treatment of adult spinal deformity (ASD). The premise is that MIS techniques will lead to equivalent outcomes and a reduction in perioperative complications when compared with open techniques. Potential issues with MIS techniques are a limited capacity to correct lumbar lordosis, unknown long-term efficacy, and the potential need for revision surgery. This study compares reoperation rates and reasons for reoperation following MIS, hybrid, and open surgery for ASD through multicenter database analysis. We retrospectively analyzed a prospective multicenter ASD database comparing open and MIS correction techniques. Inclusion criteria were: age > 18 years with minimum 20° coronal lumbar Cobb angle, a minimum of three levels fused, and minimum 2-year follow-up. Patients were propensity matched for preoperative sagittal vertebral axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and number of levels fused. ...

Research paper thumbnail of Comparison of Complications and Clinical and Radiographic Outcomes Between Nonobese and Obese Patients with Adult Spinal Deformity Undergoing Minimally Invasive Surgery

World Neurosurgery, 2016

Obesity can be associated with increased complications and potentially worse outcomes. We aimed t... more Obesity can be associated with increased complications and potentially worse outcomes. We aimed to evaluate the impact of obesity on complications and outcomes in patients with adult spinal deformity (ASD) who underwent minimally invasive surgery (MIS). Multicenter database of patients with ASD treated via MIS was queried. Of 190 patients in the database, 77 fit the inclusion criteria of 3 or more spinal levels treated minimally invasively. Patients were divided by body mass index (BMI) &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 30 (non-obese; n = 59), and BMI ≥ 30 (obese; n = 18). Mean BMI was 24.6 non-obese, and 35.0 obese (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). There were mean 3.8 interbody fusions non-obese, and 4.7 obese (p = 0.065). Levels treated posteriorly averaged 5.8 non-obese, and 5.9 obese (p = 0.502). Mean follow-up was 34.4 months non-obese, and 35.3 months obese (p = 0.976). Baseline radiographic parameters were similar between groups. Postoperatively, SVA averaged 83.9 mm obese and 20.4 mm non-obese (p = 0.002). Postoperative lumbar lordosis-pelvic incidence mismatch averaged 17.9° obese and 9.9° non-obese (p = 0.028). Both groups had improvement in ODI scores with no difference in postoperative ODI scores between groups (p = 0.090). Similarly, both groups had decreased VAS scores for back and leg pain with no difference between groups postoperatively. Twenty (33.9%) non-obese patients versus 7 (38.9%) obese patients had complications (p = 0.452). Our results suggest that obesity does not negatively impact complication rate or clinical outcomes in patients with ASD treated via MIS approaches.

Research paper thumbnail of Can a Minimal Clinically Important Difference Be Achieved in Elderly Patients with Adult Spinal Deformity Who Undergo Minimally Invasive Spinal Surgery?

World Neurosurgery, 2016

Older age has been considered a relative contraindication to complex spinal procedures. Minimally... more Older age has been considered a relative contraindication to complex spinal procedures. Minimally invasive surgery (MIS) techniques to treat patients with adult spinal deformity (ASD) have emerged with the potential benefit of decreased approach-related morbidity. To determine whether a minimal clinically important difference (MCID) could be achieved in patients aged ≥65 years with ASD who underwent MIS. Multicenter database of patients who underwent MIS for ASD was queried. Outcome metrics assessed were ODI and VAS scores for back and leg pain. Based on published reports, MCID was defined as a positive change of 12.8 ODI, 1.2 VAS back pain, and 1.6 VAS leg pain. Forty-two patients were identified. Mean age was 70.3 years, 31 (73.8%) were female. Preoperatively, mean CC, PT, pelvic incidence to lumbar lordosis (PI-LL) mismatch, and SVA were 35°, 24.6°, 14.2°, and 4.7 cm, respectively. Postoperatively, mean CC, PT, PI-LL, and SVA were 18°, 25.4°, 11.9°, and 4.9 cm, respectively. Mean 5.0 levels were treated posteriorly, and mean 4.0 interbody fusions were performed. Mean ODI improved from 47.1 to 25.1. Mean VAS back and leg pain scores improved from 6.8 and 5.9 to 2.7 and 2.7, respectively. Mean follow-up was 32.1 months. For ODI, 64.3% of patients achieved MCID. For VAS back and leg pain, 82.9% and 72.2%, respectively, reached MCID. MCID represents the threshold where patients feel a meaningful clinical improvement has occurred. Our study results suggest that the majority of elderly patients with modest ASD can achieve MCID with MIS.

Research paper thumbnail of Clinical and Radiographic Parameters Associated with Best versus Worst Clinical Outcomes in Minimally Invasive Deformity Surgery

The Spine Journal, 2015

Background. Conventional cardiac risk scores may not be completely accurate in predicting acute e... more Background. Conventional cardiac risk scores may not be completely accurate in predicting acute events because they only include factors associated with atherosclerosis, considered as the fundamental precursor of cardiovascular disease. In UK in 2006-2008 (Whitehall II study) we tested the ability of several risk scores to identify individuals with cardiac cell damage and assessed to what extent their estimates were mediated by the presence of atherosclerosis. Methods. 430 disease-free, low-risk participants were tested for high-sensitivity cardiac troponin-T (HS-CTnT) and for coronary calcification using electron-beam, dual-source, computed tomography (CAC). We analysed the data cross-sectionally using ROC curves and mediation tests. Results. When the risk scores were ranked according to the magnitude of ROC areas for HS-CTnT prediction, a score based only on age and gender came first (ROC area = 0.79), followed by Q-Risk2 (0.76), Framingham (0.70), Joint-British-Societies (0.69) and Assign (0.68). However, when the scores were ranked according to the extent of mediation by CAC (proportion of association mediated), their order was essentially reversed (age&gender = 6.8%, Q-Risk2 = 9.7%, Framingham = 16.9%, JBS = 17.8%, Assign = 17.7%). Therefore, the more accurate a score is in predicting detectable HS-CTnT, the less it is mediated by CAC; i.e. the more able a score is in capturing atherosclerosis the less it is able to predict cardiac damage. The P for trend was 0.009. Conclusions. The dynamics through which cardiac cell damage is caused cannot be explained by 'classic' heart disease risk factors alone. Further research is needed to identify precursors of heart disease other than atherosclerosis.

Research paper thumbnail of A Critical Analysis of Sagittal Plane Deformity Correction with Minimally Invasive Adult Spinal Deformity Surgery: A Two-Year Follow-Up Study

The Spine Journal, 2015

Introduction: Sagittal plane realignment is important to achieve desirable clinical outcomes afte... more Introduction: Sagittal plane realignment is important to achieve desirable clinical outcomes after adult spinal deformity (ASD) surgery. This study evaluates the impact of minimally invasive (MIS) techniques on sagittal plane alignment and clinical outcomes in ASD patients. Methods: A retrospective, multi-center review of ASD patients (age >18 years, and with one of the following: coronal Cobb >20 , sagittal vertical axis [SVA] O5 cm, and/or pelvic tilt O25), MIS surgery, and four or more levels instrumented. Patients were stratified by baseline SRS-Schwab global alignment modifier (GAM) into three groups: 0 (SVA !4 cm), þ (SVA 4e9.5 cm), or þþ (SVA O9.5 cm). Radiographic and clinical outcomes measures were analyzed with a minimum of 2-year follow-up.

Research paper thumbnail of Thoracolumbar spinal deformity

Journal of neurosurgery. Spine, 2009

Research paper thumbnail of Comparison of two minimally invasive surgery strategies to treat adult spinal deformity

Journal of neurosurgery. Spine, Jan 30, 2015

OBJECT Minimally invasive surgery (MIS) techniques are becoming a more common means of treating a... more OBJECT Minimally invasive surgery (MIS) techniques are becoming a more common means of treating adult spinal deformity (ASD). The aim of this study was to compare the hybrid (HYB) surgical approach, involving minimally invasive lateral interbody fusion with open posterior instrumented fusion, to the circumferential MIS (cMIS) approach to treat ASD. METHODS The authors performed a retrospective, multicenter study utilizing data collected in 105 patients with ASD who were treated via MIS techniques. Criteria for inclusion were age older than 45 years, coronal Cobb angle greater than 20°, and a minimum of 1 year of follow-up. Patients were stratified into 2 groups: HYB (n = 62) and cMIS (n = 43). RESULTS The mean age was 60.7 years in the HYB group and 61.0 years in the cMIS group (p = 0.910). A mean of 3.6 interbody fusions were performed in the HYB group compared with a mean of 4.0 interbody fusions in the cMIS group (p = 0.086). Posterior fusion involved a mean of 6.9 levels in the ...