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Pooya Javidan, Nima Kabirian, Gregory M. Mundis Jr., and Behrooz A. Akbarnia

The authors report a case of progressive congenital kyphoscoliosis in which the patient, a boy, originally underwent combined anterior and instrumented posterior spinal fusion at the age of 7 years and 3 months. Early proximal junctional kyphosis and implant failure mandated proximal extension of implants with 2 new rods connected to the old caudad short rods. At the 3-year follow-up, clinical and CT assessment revealed a thoracolumbar pseudarthrosis for which the patient underwent a 2-stage procedure without complication. Recordings of somatosensory evoked potentials intraoperatively were normal. Twelve hours after surgery, his neurological status started to progressively deteriorate. The patient was brought to the operating room, and the initially achieved correction was reversed by an apex-only exposure of the 4-rod system. After surgery the patient started to show progressive improvement in his neurological function. A final myelography was performed and showed free passage of the dye without evidence of obstruction. Clinically, the patient continued to improve and at his 3-month follow-up had near-complete resolution of his neurological deficits. Findings on his physical examination were normal at the final 12-year follow-up.

Despite normal findings on intraoperative neuromonitoring, a delayed neurological deficit can occur after complex spine reconstruction. Preoperative risk assessment, surgical approach, and instrumentation deserve careful attention. Advantages of a 4-rod construct are discussed in this case.

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Amir Ahmadian, Sean Verma, Gregory M. Mundis Jr., Rod J. Oskouian Jr., Donald A. Smith, and Juan S. Uribe

Object

In this study the authors report on the clinical outcomes, safety, and efficacy of lateral retroperitoneal transpsoas minimally invasive surgery–lumbar interbody fusion (MIS-LIF) at the L4–5 disc space in patients with spondylolisthesis. This approach has become an increasingly popular means of fusion. Its most frequent complication is lumbar plexus injury. Reported complication rates at the L4–5 disc space vary widely in the literature, bringing into question the safety of MIS-LIF for the L4–5 region, especially in patients with spondylolisthesis.

Methods

The authors retrospectively reviewed prospectively acquired multicenter databases of patients with Grade I and II L4–5 spondylolisthesis who had undergone elective MIS-LIF between 2008 and 2011. Clinical follow-up had been scheduled for 1, 3, 6, 12, and 24 months postoperatively. Outcome measures included estimated blood loss, operative time, length of hospital stay, integrity of construct, complications, fusion rates, visual analog scale (VAS), Oswestry Disability Index (ODI), and 36-Item Short Form Health Survey (SF-36).

Results

Eighty-four patients with L4–5 MIS-LIF were identified, 31 of whom met the study inclusion criteria: 26 adults with Grade I and 5 adults with Grade II L4–5 spondylolisthesis who had undergone elective MIS-LIF and subsequent posterior percutaneous pedicle screw fixation without surgical manipulation of the posterior elements (laminectomy, foraminotomy, facetectomy). The study cohort consisted of 9 males (29%) and 22 females (71%) with an average age of 61.5 years. The mean total blood loss was 94 ml (range 20–250 ml). The mean hospital stay and follow-up were 3.5 days and 18.2 months, respectively. The average score on the ODI improved from 50.4 preoperatively to 30.9 at the last follow-up (p < 0.0001). The SF-36 score improved from 38.1 preoperatively to 59.5 at the last follow-up (p < 0.0001). The VAS score improved from 69.9 preoperatively to 38.7 at the last follow-up (p < 0.0001). No motor weakness or permanent deficits were documented in any patient. Correction of deformity did not have any neurological complications. All patients had improvement in anterolisthesis. Residual postoperative listhesis across cases was noted in 4 patients (12.9%). Transient anterior thigh numbness (Sensory Dermal Zone III) was noted in 22.5% of patients.

Conclusions

With its established surgical corridors through the retroperitoneum and psoas muscle, the MIS-LIF combined with posterior percutaneous pedicle screw fixation/reduction is a safe, reproducible, and effective technique for patients with symptomatic degenerative spondylolisthesis at the L4–5 vertebral segment.

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Pooria Hosseini, Gregory M. Mundis Jr., Robert K. Eastlack, Ramin Bagheri, Enrique Vargas, Stacie Tran, and Behrooz A. Akbarnia

OBJECTIVE

Sagittal malalignment decreases patients’ quality of life and may require surgical correction to achieve realignment goals. High-risk posterior-based osteotomy techniques are the current standard treatment for addressing sagittal malalignment. More recently, anterior lumbar interbody fusion, anterior column realignment (ALIF ACR) has been introduced as an alternative for correction of sagittal deformity. The objective of this paper was to report clinical and radiographic results for patients treated using the ALIF-ACR technique.

METHODS

A retrospective study of 39 patients treated with ALIF ACR was performed. Patient demographics, operative details, radiographic parameters, neurological assessments, outcome measures, and preoperative, postoperative, and mean 1-year follow-up complications were studied.

RESULTS

The patient population comprised 39 patients (27 females and 12 males) with a mean follow-up of 13.3 ± 4.7 months, mean age of 66.1 ± 11.6 years, and mean body mass index of 27.3 ± 6.2 kg/m2. The mean number of ALIF levels treated was 1.5 ± 0.5. Thirty-three (84.6%) of 39 patients underwent posterior spinal fixation and 33 (84.6%) of 39 underwent posterior column osteotomy, of which 20 (60.6%) of 33 procedures were performed at the level of the ALIF ACR. Pelvic tilt, sacral slope, and pelvic incidence were not statistically significantly different between the preoperative and postoperative periods and between the preoperative and 1-year follow-up periods (except for PT between the preoperative and 1-year follow-up, p = 0.018). Sagittal vertical axis, T-1 spinopelvic inclination, lumbar lordosis, pelvic incidence–lumbar lordosis mismatch, intradiscal angle, and motion segment angle all improved from the preoperative to postoperative period and the preoperative to 1-year follow-up (p < 0.05). The changes in motion segment angle and intradiscal angle achieved in the ALIF-ACR group without osteotomy compared with the ALIF-ACR group with osteotomy at the level of ACR were not statistically significant. Total visual analog score, Oswestry Disability Index, and Scoliosis Research Society–22 scores all improved from preoperative to postoperative and preoperative to 1-year follow-up. Fourteen patients (35.9%) experienced 26 complications (15 major and 11 minor). Eleven patients required reoperation. The most common complication was proximal junctional kyphosis (6/26 complications, 23%) followed by vertebral body/endplate fracture (3/26, 12%).

CONCLUSIONS

This study showed satisfactory radiographic and clinical outcomes at the 1-year follow-up. Proximal junctional kyphosis was the most common complication followed by fracture, complications that are commonly associated with sagittal realignment surgery and may not be mitigated by the anterior approach.

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The comprehensive anatomical spinal osteotomy and anterior column realignment classification

Presented at the 2018 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Juan S. Uribe, Frank Schwab, Gregory M. Mundis Jr., David S. Xu, Jacob Januszewski, Adam S. Kanter, David O. Okonkwo, Serena S. Hu, Deviren Vedat, Robert Eastlack, Pedro Berjano, and Praveen V. Mummaneni

OBJECTIVE

Spinal osteotomies and anterior column realignment (ACR) are procedures that allow preservation or restoration of spine lordosis. Variations of these techniques enable different degrees of segmental, regional, and global sagittal realignment. The authors propose a comprehensive anatomical classification system for ACR and its variants based on the level of technical complexity and invasiveness. This serves as a common language and platform to standardize clinical and radiographic outcomes for the utilization of ACR.

METHODS

The proposed classification is based on 6 anatomical grades of ACR, including anterior longitudinal ligament (ALL) release, with varying degrees of posterior column release or osteotomies. Additionally, a surgical approach (anterior, lateral, or posterior) was added. Reliability of the classification was evaluated by an analysis of 16 clinical cases, rated twice by 14 different spine surgeons, and calculation of Fleiss kappa coefficients.

RESULTS

The 6 grades of ACR are as follows: grade A, ALL release with hyperlordotic cage, intact posterior elements; grade 1 (ACR + Schwab grade 1), additional resection of the inferior facet and joint capsule; grade 2 (ACR + Schwab grade 2), additional resection of both superior and inferior facets, interspinous ligament, ligamentum flavum, lamina, and spinous process; grade 3 (ACR + Schwab grade 3), additional adjacent-level 3-column osteotomy including pedicle subtraction osteotomy; grade 4 (ACR + Schwab grade 4), 2-level distal 3-column osteotomy including pedicle subtraction osteotomy and disc space resection; and grade 5 (ACR + Schwab grade 5), complete or partial removal of a vertebral body and both adjacent discs with or without posterior element resection. Intraobserver and interobserver reliability were 97% and 98%, respectively, across the 14-reviewer cohort.

CONCLUSIONS

The proposed anatomical realignment classification provides a consistent description of the various posterior and anterior column release/osteotomies. This reliability study confirmed that the classification is consistent and reproducible across a diverse group of spine surgeons.

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Jakub Godzik, Bernardo de Andrada Pereira, Anna G. U. Sawa, Jennifer N. Lehrman, Gregory M. Mundis Jr., Randall J. Hlubek, Juan S. Uribe, Brian P. Kelly, and Jay D. Turner

OBJECTIVE

Anterior column realignment (ACR) is a new minimally invasive approach for deformity correction that achieves a degree of lordosis similar to that obtained with pedicle subtraction osteotomy (PSO). This study compared the biomechanical profiles of ACR with PSO using range of motion (ROM) and posterior rod strain (RS) to gain insight into the ACR technique and the necessary surgical strategies to optimize longevity and stability.

METHODS

An in vitro biomechanical study using standard flexibility testing (7.5 Nm) was performed on 14 human cadaveric specimens, separated into 2 groups similar in age, sex, bone mineral density, and intact ROM. For group 1 (n = 7, instrumented L1–S1), a 30° ACR was performed at L3–4. For group 2 (n = 7, instrumented T12–S1), a 30° L3 PSO was performed. Specimens were subjected to nondestructive loads in flexion, extension, axial rotation, lateral bending, and compression. Conditions tested were 1) intact, 2) pedicle screw with 2 rods (PSR), 3) ACR or PSO with 2 rods (+2R), and 4) ACR or PSO with 4 rods (+4R). Primary outcome measures of interest were ROM stability and posterior RS at L3–4.

RESULTS

No difference was observed between groups in lumbar lordosis (p = 0.83) or focal angular lordosis at L3–4 (p = 0.75). No differences in stability were observed between ACR+2R and PSO+2R (p ≥ 0.06);​ however, ACR+2R was significantly less stable than PSR in flexion and extension (p ≤ 0.02), whereas PSO+2R was less stable than PSR only in extension (p = 0.04). ACR+4R was more stable than ACR+2R in flexion, extension, left axial rotation, and compression (p ≤ 0.02). PSO+4R was more stable than PSO+2R only in extension (p = 0.04). Both ACR+2R and PSO+2R resulted in significant increases in RS in flexion and extension compared with PSR (p ≤ 0.032). RS in flexion and extension decreased significantly for ACR+4R versus ACR+2R and for PSO+4R versus PSO+2R (p ≤ 0.047). PSO+2R yielded lower RS than ACR+2R in compression (p = 0.03). No differences existed in RS between ACR+4R and PSO+4R (p ≥ 0.05).

CONCLUSIONS

Although ACR appeared to be slightly more destabilizing than PSO using traditional 2R fixation, both techniques resulted in significant increases in posterior RS. The 4R technique increased stability in ACR and decreased RS in both ACR and PSO but may be more beneficial in ACR. Longer-term clinical studies are needed to appropriately identify the durability of the ACR technique in deformity correction.

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Kseniya Slobodyanyuk, Caroline E. Poorman, Justin S. Smith, Themistocles S. Protopsaltis, Richard Hostin, Shay Bess, Gregory M. Mundis Jr., Frank J. Schwab, and Virginie Lafage

Object

The goal of this study was to determine the outcome and risk factors in patients with adult spinal deformity (ASD) who elected to receive nonoperative care.

Methods

In this retrospective study the authors reviewed a nonoperative branch of the International Spine Study Group database, derived from 10 sites across the US. Specific inclusion criteria included nonoperative treatment for ASD and the availability of Scoliosis Research Society (SRS)-22 scores and radiographic data at baseline (BL) and at 1-year (1Y) follow-up. Health-related quality of life measures were assessed using the SRS-22 and radiographic data. Changes in SRS-22 scores were evaluated by domain and expressed in number of minimum clinically important differences (MCIDs) gained or lost; BL and 1Y scores were also compared with age- and sex-matched normative references.

Results

One hundred eighty-nine patients (mean age 53 years, 86% female) met inclusion criteria. Pain was the domain with the largest offset for 43% of patients, followed by the Appearance (23%), Activity (18%), and Mental (15%) domains. On average, patients improved 0.3 MCID in Pain over 1Y, without changes in Activity or Appearance. Baseline scores significantly impacted 1Y outcomes, with up to 85% of patients in the mildest category of deformity being classified as < 1 MCID of normative reference at 1Y, versus 0% of patients with the most severe initial deformity. Baseline radiographic parameters did not correlate with outcome.

Conclusions

Patients who received nonoperative care are significantly more disabled than age- and sex-matched normative references. The likelihood for a patient to reach SRS scores similar to the normative reference at 1Y decreases with increased BL disability. Nonoperative treatment is a viable option for certain patients with ASD, and up to 24% of patients demonstrated significant improvement over 1Y with nonoperative care.

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Christopher P. Ames, Justin S. Smith, Justin K. Scheer, Christopher I. Shaffrey, Virginie Lafage, Vedat Deviren, Bertrand Moal, Themistocles Protopsaltis, Praveen V. Mummaneni, Gregory M. Mundis Jr., Richard Hostin, Eric Klineberg, Douglas C. Burton, Robert Hart, Shay Bess, Frank J. Schwab, and the International Spine Study Group

Object

Cervical spine osteotomies are powerful techniques to correct rigid cervical spine deformity. Many variations exist, however, and there is no current standardized system with which to describe and classify cervical osteotomies. This complicates the ability to compare outcomes across procedures and studies. The authors' objective was to establish a universal nomenclature for cervical spine osteotomies to provide a common language among spine surgeons.

Methods

A proposed nomenclature with 7 anatomical grades of increasing extent of bone/soft tissue resection and destabilization was designed. The highest grade of resection is termed the major osteotomy, and an approach modifier is used to denote the surgical approach(es), including anterior (A), posterior (P), anterior-posterior (AP), posterior-anterior (PA), anterior-posterior-anterior (APA), and posterior-anterior-posterior (PAP). For cases in which multiple grades of osteotomies were performed, the highest grade is termed the major osteotomy, and lower-grade osteotomies are termed minor osteotomies. The nomenclature was evaluated by 11 reviewers through 25 different radiographic clinical cases. The review was performed twice, separated by a minimum 1-week interval. Reliability was assessed using Fleiss kappa coefficients.

Results

The average intrarater reliability was classified as “almost perfect agreement” for the major osteotomy (0.89 [range 0.60–1.00]) and approach modifier (0.99 [0.95–1.00]); it was classified as “moderate agreement” for the minor osteotomy (0.73 [range 0.41–1.00]). The average interrater reliability for the 2 readings was the following: major osteotomy, 0.87 (“almost perfect agreement”); approach modifier, 0.99 (“almost perfect agreement”); and minor osteotomy, 0.55 (“moderate agreement”). Analysis of only major osteotomy plus approach modifier yielded a classification that was “almost perfect” with an average intrarater reliability of 0.90 (0.63–1.00) and an interrater reliability of 0.88 and 0.86 for the two reviews.

Conclusions

The proposed cervical spine osteotomy nomenclature provides the surgeon with a simple, standard description of the various cervical osteotomies. The reliability analysis demonstrated that this system is consistent and directly applicable. Future work will evaluate the relationship between this system and health-related quality of life metrics.

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Justin K. Scheer, Justin S. Smith, Frank Schwab, Virginie Lafage, Christopher I. Shaffrey, Shay Bess, Alan H. Daniels, Robert A. Hart, Themistocles S. Protopsaltis, Gregory M. Mundis Jr., Daniel M. Sciubba, Tamir Ailon, Douglas C. Burton, Eric Klineberg, Christopher P. Ames, and The International Spine Study Group

OBJECTIVE

The operative management of patients with adult spinal deformity (ASD) has a high complication rate and it remains unknown whether baseline patient characteristics and surgical variables can predict early complications (intraoperative and perioperative [within 6 weeks]). The development of an accurate preoperative predictive model can aid in patient counseling, shared decision making, and improved surgical planning. The purpose of this study was to develop a model based on baseline demographic, radiographic, and surgical factors that can predict if patients will sustain an intraoperative or perioperative major complication.

METHODS

This study was a retrospective analysis of a prospective, multicenter ASD database. The inclusion criteria were age ≥ 18 years and the presence of ASD. In total, 45 variables were used in the initial training of the model including demographic data, comorbidities, modifiable surgical variables, baseline health-related quality of life, and coronal and sagittal radiographic parameters. Patients were grouped as either having at least 1 major intraoperative or perioperative complication (COMP group) or not (NOCOMP group). An ensemble of decision trees was constructed utilizing the C5.0 algorithm with 5 different bootstrapped models. Internal validation was accomplished via a 70/30 data split for training and testing each model, respectively. Overall accuracy, the area under the receiver operating characteristic (AUROC) curve, and predictor importance were calculated.

RESULTS

Five hundred fifty-seven patients were included: 409 (73.4%) in the NOCOMP group, and 148 (26.6%) in the COMP group. The overall model accuracy was 87.6% correct with an AUROC curve of 0.89 indicating a very good model fit. Twenty variables were determined to be the top predictors (importance ≥ 0.90 as determined by the model) and included (in decreasing importance): age, leg pain, Oswestry Disability Index, number of decompression levels, number of interbody fusion levels, Physical Component Summary of the SF-36, Scoliosis Research Society (SRS)–Schwab coronal curve type, Charlson Comorbidity Index, SRS activity, T-1 pelvic angle, American Society of Anesthesiologists grade, presence of osteoporosis, pelvic tilt, sagittal vertical axis, primary versus revision surgery, SRS pain, SRS total, use of bone morphogenetic protein, use of iliac crest graft, and pelvic incidence–lumbar lordosis mismatch.

CONCLUSIONS

A successful model (87% accuracy, 0.89 AUROC curve) was built predicting major intraoperative or perioperative complications following ASD surgery. This model can provide the foundation toward improved education and point-of-care decision making for patients undergoing ASD surgery.

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Alexander A. Theologis, Gregory M. Mundis Jr., Stacie Nguyen, David O. Okonkwo, Praveen V. Mummaneni, Justin S. Smith, Christopher I. Shaffrey, Richard Fessler, Shay Bess, Frank Schwab, Bassel G. Diebo, Douglas Burton, Robert Hart, Vedat Deviren, and Christopher Ames

OBJECTIVE

The aim of this study was to evaluate the utility of supplementing long thoracolumbar posterior instrumented fusion (posterior spinal fusion, PSF) with lateral interbody fusion (LIF) of the lumbar/thoracolumbar coronal curve apex in adult spinal deformity (ASD).

METHODS

Two multicenter databases were evaluated. Adults who had undergone multilevel LIF of the coronal curve apex in addition to PSF with L5–S1 interbody fusion (LS+Apex group) were matched by number of posterior levels fused with patients who had undergone PSF with L5–S1 interbody fusion without LIF (LS-Only group). All patients had at least 2 years of follow-up. Percutaneous PSF and 3-column osteotomy (3CO) were excluded. Demographics, perioperative details, radiographic spinal deformity measurements, and HRQoL data were analyzed.

RESULTS

Thirty-two patients were matched (LS+Apex: 16; LS: 16) (6 men, 26 women; mean age 63 ± 10 years). Overall, the average values for measures of deformity were as follows: Cobb angle > 40°, sagittal vertical axis (SVA) > 6 cm, pelvic tilt (PT) > 25°, and mismatch between pelvic incidence (PI) and lumbar lordosis (LL) > 15°. There were no significant intergroup differences in preoperative radiographic parameters, although patients in the LS+Apex group had greater Cobb angles and less LL. Patients in the LS+Apex group had significantly more anterior levels fused (4.6 vs 1), longer operative times (859 vs 379 minutes), and longer length of stay (12 vs 7.5 days) (all p < 0.01). For patients in the LS+Apex group, Cobb angle, pelvic tilt (PT), lumbar lordosis (LL), PI-LL (lumbopelvic mismatch), Oswestry Disability Index (ODI) scores, and visual analog scale (VAS) scores for back and leg pain improved significantly (p < 0.05). For patients in the LS-Only group, there were significant improvements in Cobb angle, ODI score, and VAS scores for back and leg pain. The LS+Apex group had better correction of Cobb angles (56% vs 33%, p = 0.02), SVA (43% vs 5%, p = 0.46), LL (62% vs 13%, p = 0.35), and PI-LL (68% vs 33%, p = 0.32). Despite more LS+Apex patients having major complications (56% vs 13%; p = 0.02) and postoperative leg weakness (31% vs 6%, p = 0.07), there were no intergroup differences in 2-year outcomes.

CONCLUSIONS

Long open posterior instrumented fusion with or without multilevel LIF is used to treat a variety of coronal and sagittal adult thoracolumbar deformities. The addition of multilevel LIF to open PSF with L5–S1 interbody support in this small cohort was often used in more severe coronal and/or lumbopelvic sagittal deformities and offered better correction of major Cobb angles, lumbopelvic parameters, and SVA than posterior-only operations. As these advantages came at the expense of more major complications, more leg weakness, greater blood loss, and longer operative times and hospital stays without an improvement in 2-year outcomes, future investigations should aim to more clearly define deformities that warrant the addition of multilevel LIF to open PSF and L5–S1 interbody fusion.