Treatment of sacroiliac joint laxity-induced coronal imbalance with the kickstand rod technique.

BACKGROUND: Considerations of the sacroiliac joint (SIJ) and its role in causing lower back and limb pain have taken a secondary role ever since Mixter and Barr's hallmark article in 1934 on the herniated nucleus pulposus. However, recent literature has highlighted the contribution of sacroiliac joint degeneration in the development of failed back surgery syndrome (FBSS), especially in patients undergoing lumbar or lumbosacral spinal fusion surgeries. Many reports have studied the anatomy, physiology, and clinical significance of the sacroiliac joint, but none have linked its dysfunction with other spinal deformities. CASE DESCRIPTION: A 63-year-old female with a history of multiple complex instrumented spinal fusions presented to our institution with progressive leftward coronal imbalance despite successful arthrodesis from T3 through S1. She was initially treated with decompression and reimplantation, but adjacent segment disease at the SIJ led to laxity, distal failure, and a worsening coronal deformity. A mechanical fall after her decompression surgery led to a dramatically increased coronal imbalance, which was ultimately treated using Lenke's kickstand rod technique. At 3.5 years follow up, the patient's coronal balance remains stable. CONCLUSION: Few studies have related SIJ degeneration and laxity with spinal deformity. Our case describes SIJ degeneration that evolved to joint laxity, which ultimately produced a leftward coronal imbalance according to the adjacent segment disease mechanism. Additionally, we describe the use of a kickstand rod to effectively correct the coronal imbalance, reduce pain levels, promote SIJ arthrodesis, and prevent further SIJ-related issues without significant complications over 3 years post-operation.

Geometric analysis of pedicle subtraction osteotomy (PSO) for Kyphosis correction: anterior lengthening may occur at the osteotomized body as well as at the discs above and below.

OBJECTIVE: To validate the authors kyphosis correction formula for pedicle subtraction osteotomy (PSO) cases. Additionally, to use the formula to evaluate the safety of PSO by determining if there is anterior lengthening. METHODS: Twenty-two patients with primarily kyphosis corrected by PSO and with clear landmarks on preoperative and postoperative x-rays were selected. Several anatomical lines and angle measurements were utilized as depicted previously in the Vertebral Column Resection formula (see below). Two approximations were calculated: the geometric approximation (G) = (tanG°*2 + 1)*15° and the rough approximation (R) which is about the same amount of actual shortening (x), if parallel length (y) ≥ 40; twice of x, if y < 40. For each patient, the change of segmental kyphosis angle (K°) was measured and compared with G° and R°, and the correlation between each value was analyzed. RESULTS: The absolute Mean ± SE for K - G and K - R was 2.33° ± 0.34 and 6.09° ± 0.58, respectively. K - G is < 3° (p = 0.03). K - R is < 8° (p = 0.001). In other words, K was close to G and R and thus can be predicted by these approximations. Average posterior shortening, anterior shortening, and kyphosis correction at each level were 20.8 ± 2.0 mm, - 3.64 ± 1.5 mm (which equates to anterior lengthening), and 31.05° ± 2.0, respectively. Anterior lengthening occurred in 13 cases (in 4 cases, both at the body as well as at the disc above and below.) The correlation between posterior and anterior shortening was 0.03 (p = 0.88). There were 3 cage insertion cases: 1 had anterior lengthening, while 2 had anterior shortening even with the cage. CONCLUSION: This study validated the geometric and rough approximations originally used in PVCR patients, for PSO patients. Additionally, this study found that anterior lengthening may occur in PSOs usually at the discs, but occasionally at the osteotomized body.

Utility of Screening for Cerebral Vasospasm Using Digital Subtraction Angiography.

BACKGROUND AND PURPOSE: Cerebral arterial vasospasm (CVS) is a common complication of aneurysmal subarachnoid hemorrhage strongly associated with neurological deterioration and delayed cerebral ischemia (DCI). The utility of screening for CVS as a surrogate for early detection of DCI, especially in patients without clinical signs of DCI, remains uncertain. METHODS: We performed a retrospective analysis of 116 aneurysmal subarachnoid hemorrhage patients who underwent screening digital subtraction angiography to determine the association of significant CVS and subsequent development of DCI. Patients were stratified into 3 groups: (1) no symptoms of DCI before screening, (2) ≥1 episodes of suspected DCI symptoms before screening, and (3) unable to detect symptoms because of poor examination. RESULTS: Patients asymptomatic before screening had significantly lower rates of CVS (18%) compared with those with transient symptoms of DCI (60%; P<0.0001). None of the 79 asymptomatic patients developed DCI after screening, regardless of digital subtraction angiography findings, compared with 56% of those with symptoms (P<0.0001). Presence of CVS was significantly associated with DCI in those with transient symptoms and in those whose examinations did not permit clear assessment (odds ratio 16.0, 95% confidence interval 2.2-118.3, P=0.003). CONCLUSIONS: Patients asymptomatic before screening have low rates of CVS and seem to be at negligible risk of developing DCI. Routine screening of asymptomatic patients seems to have little utility. Screening may still be considered in patients with possible symptoms of DCI or those with examinations too poor to clinically detect symptoms because finding CVS may be useful for risk stratification and guiding management.

Idiopathic scoliosis and the vestibular system.

PURPOSE: Despite its high prevalence, the etiology underlying idiopathic scoliosis remains unclear. Although initial scrutiny has focused on genetic, biochemical, biomechanical, nutritional and congenital causes, there is growing evidence that aberrations in the vestibular system may play a role in the etiology of scoliosis. In this article, we discuss putative mechanisms for adolescent idiopathic scoliosis and review the current evidence supporting a role for the vestibular system in adolescent idiopathic scoliosis. METHODS: A comprehensive search of the English literature was performed using PubMed ( http://www.ncbi.nlm.nih.gov/pubmed ). Research articles studying interactions between adolescent idiopathic scoliosis and the vestibular system were selected and evaluated for inclusion in a literature review. RESULTS: Eighteen manuscripts of level 3-4 clinical evidence to support an association between adolescent idiopathic scoliosis (AIS) and dysfunction of the vestibular system were identified. These studies include data from physiologic and morphologic studies in humans. Clinical data are supported by animal model studies to suggest a causative link between the vestibular system and AIS. CONCLUSIONS: Clinical data and a limited number of animal model studies suggest a causative role of the vestibular system in AIS, although this association has not been reproduced in all studies.

Predictors of Postoperative Segmental and Overall Lumbar Lordosis in Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Consecutive Case Series.

STUDY DESIGN: Retrospective Case-Series. OBJECTIVES: Due to heterogeneity in previous studies, the effect of MI-TLIF on postoperative segmental lordosis (SL) and lumbar lordosis (LL) remains unclear. Therefore, we aim to identify radiographic factors associated with lordosis after surgery in a homogenous series of MI-TLIF patients. METHODS: A single-center retrospective review identified consecutive patients who underwent single-level MI-TLIF for grade 1 degenerative spondylolisthesis from 2015-2020. All surgeries underwent unilateral facetectomies and a contralateral facet release with expandable interbody cages. PROs included the ODI and NRS-BP for low-back pain. Radiographic measures included SL, disc height, percent spondylolisthesis, cage positioning, LL, PI-LL mismatch, sacral-slope, and pelvic-tilt. Surgeries were considered "lordosing" if the change in postoperative SL was ≥ +4° and "kyphosing" if ≤ -4°. Predictors of change in SL/LL were evaluated using Pearson's correlation and multivariable regression. RESULTS: A total of 73 patients with an average follow-up of 22.5 (range 12-61) months were included. Patients experienced significant improvements in ODI (29% ± 22% improvement, P < .001) and NRS-BP (3.3 ± 3 point improvement, P < .001). There was a significant increase in mean SL (Δ3.43° ± 4.37°, P < .001) while LL (Δ0.17° ± 6.98°, P > .05) remained stable. Thirty-eight (52%) patients experienced lordosing MI-TLIFs, compared to 4 (5%) kyphosing and 31 (43%) neutral MI-TLIFs. A lower preoperative SL and more anterior cage placement were associated with the greatest improvement in SL (ß = -.45° P = .001, ß = 15.06° P < .001, respectively). CONCLUSIONS: In our series, the majority of patients experienced lordosing or neutral MI-TLIFs (n = 69, 95%). Preoperative radiographic alignment and anterior cage placement were significantly associated with target SL following MI-TLIF.

Association Between Neighborhood-Level Socioeconomic Disadvantage and Patient-Reported Outcomes in Lumbar Spine Surgery.

BACKGROUND: Despite an increased understanding of the impact of socioeconomic status on neurosurgical outcomes, the impact of neighborhood-level social determinants on lumbar spine surgery patient-reported outcomes remains unknown. OBJECTIVE: To evaluate the impact of geographic social deprivation on physical and mental health of lumbar surgery patients. METHODS: A single-center retrospective cohort study analyzing patients undergoing lumbar surgery for degenerative disease from 2015 to 2018 was performed. Surgeries were categorized as decompression only or decompression with fusion. The area deprivation index was used to define social deprivation. Study outcomes included preoperative and change in Patient-Reported Outcomes Measurement (PROMIS) physical function (PF), pain interference (PI), depression, and anxiety (mean follow-up: 43.3 weeks). Multivariable imputation was performed for missing data. One-way analysis of variance and multivariable linear regression were used to evaluate the association between area deprivation index and PROMIS scores. RESULTS: In our cohort of 2010 patients, those with the greatest social deprivation had significantly worse mean preoperative PROMIS scores compared with the least-deprived cohort (mean difference [95% CI]-PF: -2.5 [-3.7 to -1.4]; PI: 3.0 [2.0-4.1]; depression: 5.5 [3.4-7.5]; anxiety: 6.0 [3.8-8.2], all P < .001), without significant differences in change in these domains at latest follow-up (PF: +0.5 [-1.2 to 2.2]; PI: -0.2 [-1.7 to 2.1]; depression: -2 [-4.0 to 0.1]; anxiety: -2.6 [-4.9 to 0.4], all P > .05). CONCLUSION: Lumbar spine surgery patients with greater social deprivation present with worse preoperative physical and mental health but experience comparable benefit from surgery than patients with less deprivation, emphasizing the need to further understand social and health factors that may affect both disease severity and access to care.

Rapid Implementation of a 3-Dimensional-Printed Patient-Specific Titanium Sacrum Implant for Severe Neuropathic Spinal Arthropathy and Guide to Compassionate US Regulatory Approval.

BACKGROUND AND OBJECTIVE: Rapid design and production of patient-specific 3-dimensional-printed implants (3DPIs) present a novel opportunity to restore the biomechanically demanding integrity of the lumbopelvic junction. We present a unique case of a 61-year-old patient with severe neuropathic spinal arthropathy (Charcot spine) who initially underwent a T4-to-sacrum spinal fusion. Massive bone destruction led to dissociation of his upper body from his pelvis and legs. Reconstruction of the spinopelvic continuity was planned with the aid of a personalized lumbosacral 3DPI. METHOD: Using high-resolution computed tomography scans, the custom 3DPI was made using additive titanium manufacturing. The unique 3DPI consisted of (1) a sacral platform with iliac screws, (2) modular corpectomy device with rigid connection to the sacral platform, and (3) anterior plate connection with screws for proximal fixation. The procedures to obtain compassionate use Food and Drug Administration approval were followed. The patient underwent debridement of a chronically open wound before undertaking the 3-stage reconstructive procedure. The custom 3DPI and additional instrumentation were inserted as part of a salvage rebuilding procedure. RESULTS: The chronology of the rapid implementation of the personalized sacral 3DPI from decision, design, manufacturing, Food and Drug Administration approval, and surgical execution lasted 28 days. The prosthesis was positioned in the defect according to the expected anatomic planes and secured using a screw-rod system and a vascularized fibular bone strut graft. The prosthesis provided an ideal repair of the lumbosacral junction and pelvic ring by merging spinal pelvic fixation, posterior pelvic ring fixation, and anterior spinal column fixation. CONCLUSION: To the best of our knowledge, this is the first case of a multilevel lumbar, sacral, and sacropelvic neuropathic (Charcot) spine reconstruction using a 3DPI sacral prosthesis. As the prevalence of severe spine deformities continues to increase, adoption of 3DPIs is becoming more relevant to offer personalized treatment for complex deformities.

Impact of lateral mass anatomic variation on ideal polyaxial screw head mobility: technical considerations.

OBJECTIVE: To assess optimal angulation characteristics of lateral mass screws for subaxial (C3 to C6) fixation of the cervical spine in the neutral position. BACKGROUND: In the typical Magerl or Anderson placement technique, the screw trajectory is ideally parallel to the facet joint. For the rod and screw to align properly, the screw head must rotate enough to become perpendicular to the rod. If the optimal angle for the screw head is limited by the screw design, abnormal torsional forces will be generated at the rod/screw interface inducing kyphosis. In this paper, we examined the spinal anatomy in patients with normal CTs to determine the necessary range of motion between tulip head and screw to prevent forced persuasion and abnormal cervical spine alignment. METHODS: We examined subaxial radiographs of 292 vertebrae from C3 to C6 in 73 normal subjects. Computed tomography (CT) scans of the cervical spine with multiplanar reconstructions were evaluated in the axial and sagittal planes. A planned screw entry angle of 30° based upon the midpoint of the lateral mass was used in the axial plane, and parallel to the facet joint in the sagittal plane. The screw head angle (SHA) was then calculated from this 3D measured angle. RESULTS: The measured SHA ranged from 27 to 60°. The average SHA was 43.8°. The average SHA was not significantly different between the levels measured with consistent range and standard deviation. Seventy-six percent (223/292) of levels measured required a SHA >40°, and 12% (36/292) required a SHA >50°. CONCLUSION: The authors recommend using cervical instrumentation systems that allow for at least 55° of freedom of the polyaxial head to prevent abnormal segmental forces. In systems with lesser angulation, technique modifications must be applied to prevent translational forces.

Pharyngoesophageal Damage from Hardware Extrusion at an Average of 7.5 Years After Anterior Cervical Diskectomy and Fusion: A Case Series, Discussion of Risk Factors, and Guide for Management.

OBJECTIVE: We present a single-institution case series of patients who experienced pharyngoesophageal damage, specifically from extruded hardware occurring at an average of 7.5 years after anterior cervical diskectomy and fusion (ACDF). METHODS: A retrospective chart review was conducted of patients who had undergone ACDF with subsequent delayed pharyngoesophageal perforation or erosion from extruded hardware ≥1 year after surgery. A discussion of the literature surrounding this complication, including risk factors and management, is also presented. RESULTS: Nine patients were identified (average age 58 years, 66.7% male) among a total of 4122 ACDF patients (incidence: 0.22%). Average time to injury was 7.5 years. Indications for initial ACDF were degenerative cervical disease (n = 7), ankylosing spondylitis (n = 1), and cervical fracture (n = 1). Eight patients had prior multilevel ACDF spanning 2 (n = 4), 3 (n = 1), or 4 levels (n = 2). Fusion levels for prior ACDF included C5-C7 (n = 3), C3-C7 (n = 2), C4-C7 (n = 1), C4-C6 (n = 1), C2-C5 (n = 1), and C6-C7 (n = 1). Pharyngoesophageal injuries included esophageal perforation (n = 3), pharyngeal perforation (n = 2), esophageal erosion (n = 3), and pharyngoesophageal erosion (n = 1). In most (n = 6) cases, the cause of pharyngoesophageal damage was due to ≥1 extruded screws. Dysphagia (n = 8) was the most common presenting symptom. For perforations (n = 5), 2 repairs used a rotational flap to reinforce a primary closure; the other 3 cases were repaired via primary closure. CONCLUSIONS: Pharyngoesophageal damage caused by extruded hardware may occur several years after ACDF. These delayed complications are difficult to predict. Proper screw placement may be the most important factor for minimizing the chances of this potentially devastating complication, particularly with multilevel constructs.

Comparison of local and regional radiographic outcomes in minimally invasive and open TLIF: a propensity score-matched cohort.

OBJECTIVE: Local and regional radiographic outcomes following minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) versus open TLIF remain unclear. The purpose of this study was to provide a comprehensive assessment of local and regional radiographic parameters following MI-TLIF and open TLIF. The authors hypothesized that open TLIF provides greater segmental and global lordosis correction than MI-TLIF. METHODS: A single-center retrospective cohort study of consecutive patients undergoing MI- or open TLIF for grade I degenerative spondylolisthesis was performed. One-to-one nearest-neighbor propensity score matching (PSM) was used to match patients who underwent open TLIF to those who underwent MI-TLIF. Sagittal segmental radiographic measures included segmental lordosis (SL), anterior disc height (ADH), posterior disc height (PDH), foraminal height (FH), percent spondylolisthesis, and cage position. Lumbopelvic radiographic parameters included overall lumbar lordosis (LL), pelvic incidence (PI)-lumbar lordosis (PI-LL) mismatch, sacral slope (SS), and pelvic tilt (PT). Change in segmental or overall lordosis after surgery was considered "lordosing" if the change was > 0° and "kyphosing" if it was ≤ 0°. Student t-tests or Wilcoxon rank-sum tests were used to compare outcomes between MI-TLIF and open-TLIF groups. RESULTS: A total of 267 patients were included in the study, 114 (43%) who underwent MI-TLIF and 153 (57%) who underwent open TLIF, with an average follow-up of 56.6 weeks (SD 23.5 weeks). After PSM, there were 75 patients in each group. At the latest follow-up both MI- and open-TLIF patients experienced significant improvements in assessment scores obtained with the Oswestry Disability Index (ODI) and the numeric rating scale for low-back pain (NRS-BP), without significant differences between groups (p > 0.05). Both MI- and open-TLIF patients experienced significant improvements in SL, ADH, and percent corrected spondylolisthesis compared to baseline (p < 0.001). However, the MI-TLIF group experienced significantly larger magnitudes of correction with respect to these metrics (ΔSL 4.14° ± 4.35° vs 1.15° ± 3.88°, p < 0.001; ΔADH 4.25 ± 3.68 vs 1.41 ± 3.77 mm, p < 0.001; percent corrected spondylolisthesis: -10.82% ± 6.47% vs -5.87% ± 8.32%, p < 0.001). In the MI-TLIF group, LL improved in 44% (0.3° ± 8.5°) of the cases, compared to 48% (0.9° ± 6.4°) of the cases in the open-TLIF group (p > 0.05). Stratification by operative technique (unilateral vs bilateral facetectomy) and by interbody device (static vs expandable) did not yield statistically significant differences (p > 0.05). CONCLUSIONS: Both MI- and open-TLIF patients experienced significant improvements in patient-reported outcome (PRO) measures and local radiographic parameters, with neutral effects on regional alignment. Surprisingly, in our cohort, change in SL was significantly greater in MI-TLIF patients, perhaps reflecting the effect of operative techniques, technological innovations, and the preservation of the posterior tension band. Taking these results together, no significant overall differences in LL between groups were demonstrated, which suggests that MI-TLIF is comparable to open approaches in providing radiographic correction after surgery. These findings suggest that alignment targets can be achieved by either MI- or open-TLIF approaches, highlighting the importance of surgeon attention to these variables.

Decompression of Lumbar Central Spinal Canal Stenosis Following Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: This was a retrospective clinical series. OBJECTIVE: The objective of this study was to evaluate radiologic changes in central spinal canal dimensions following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with placement of a static or an expandable interbody device. SUMMARY OF BACKGROUND DATA: MIS-TLIF is used to treat lumbar degenerative diseases and low-grade spondylolisthesis. MIS-TLIF enables direct and indirect decompression of lumbar spinal stenosis, with patients experiencing relief from radiculopathy and neurogenic claudication. However, the effects of MIS-TLIF on the central spinal canal are not well-characterized. MATERIALS AND METHODS: We identified patients who underwent MIS-TLIF for degenerative lumbar spondylolisthesis and concurrent moderate to severe spinal stenosis. We selected patients who had both preoperative and postoperative magnetic resonance imaging (MRI) and upright lateral radiographs of the lumbar spine. Measurements on axial T2-weighted MRI scans include anteroposterior and transverse dimensions of the dural sac and osseous spinal canal. Measurements on radiographs include disk height, neural foraminal height, segmental lordosis, and spondylolisthesis. We made pairwise comparisons between each of the central canal dimensions and lumbar sagittal segmental radiologic outcome measures relative to their corresponding preoperative values. Correlation coefficients were used to quantify the association between changes in lumbar sagittal segmental parameters relative to changes in radiologic outcomes of central canal dimensions. Statistical analysis was performed for "all patients" and further stratified by interbody device subgroups (static and expandable). RESULTS: Fifty-one patients (age 60.4 y, 68.6% female) who underwent MIS-TLIF at 55 levels (65.5% at L4-L5) were included in the analysis. Expandable interbody devices were used in 45/55 (81.8%) levels. Mean duration from surgery to postoperative MRI scan was 16.5 months (SD 11.9). MIS-TLIF was associated with significant improvements in dural sac dimensions (anteroposterior +0.31 cm, transverse +0.38 cm) and osseous spinal canal dimensions (anteroposterior +0.16 cm, transverse +0.32 cm). Sagittal lumbar segmental parameters of disk height (+0.56 cm), neural foraminal height (+0.35 cm), segmental lordosis (+4.26 degrees), and spondylolisthesis (-7.5%) were also improved following MIS-TLIF. We did not find meaningful associations between the changes in central canal dimensions relative to the corresponding changes in any of the sagittal lumbar segmental parameters. Stratified analysis by interbody device type (static and expandable) revealed similar within-group changes as in the overall cohort and minimal between-group differences. CONCLUSIONS: MIS-TLIF is associated with radiologic decompression of neural foraminal and central spinal canal stenosis. The mechanism for neural foraminal and central canal decompression is likely driven by a combination of direct and indirect corrective techniques.

Osteotomies in the posterior-only treatment of complex adult spinal deformity: a comparative review.

In addressing adult spinal deformities through a posterior approach, the surgeon now may choose from among a variety of osteotomy techniques. The Ponte or Smith-Petersen osteotomy provides the least correction, but it can be used at multiple levels with minimal blood loss and a lower operative risk. Pedicle subtraction osteotomies provide nearly 3 times the per-level correction of Ponte/Smith-Petersen osteotomies but carry increased technical demands, longer operative time, and greater blood loss and associated morbidity. Vertebral column resections serve as the most powerful method, providing the most correction in the coronal and sagittal planes, but posing both the greatest technical challenge and the greatest risk to the patient in terms of possible neurological injury, operative time, and potential morbidity. The authors reviewed the literature relating to these osteotomy methods. They also provided case illustrations and suggestions for their proper application.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part I: 2-Dimensional Operative Video and Technical Report.

BACKGROUND: Advances in operative techniques and minimally invasive technologies have evolved to maximize patient outcomes and radiographic results, while reducing morbidity and recovery time. OBJECTIVE: To describe the operative technique for a transfacet minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) as a proposed modification to the standard approach MIS-TLIF. METHODS: We present the case of a 72-yr-old man with left-sided lumbar radiculopathy. Preoperative imaging demonstrated degenerative lumbar anterolisthesis at L4-5, with associated canal and neuroforaminal stenosis. The patient underwent transfacet MIS-TLIF at L4-L5. We describe the preoperative planning, patient positioning, incision and dissection, pedicle screw insertion, transfacet approach to the working access corridor, discectomy, interbody device placement, fixation, and closure. RESULTS: The transfacet MIS-TLIF utilizes 3 key techniques to safely maximize surgical correction: (1) a limited bony resection based on the superior articular process, leaving the medial inferior articular process, lateral superior articular process, and rostral pars intact, providing a working bony corridor that protects the traversing and exiting nerve roots; (2) decortication and release of the contralateral facet joint to provide additional capacity for indirect decompression and provide the first point of osseous fusion; and (3) placement of an expandable interbody device that provides additional indirect decompression to the working side and contralateral foramen. CONCLUSION: The transfacet MIS-TLIF uniquely leverages a bony working corridor to access the disc space for discectomy and interbody placement. Transfacet MIS-TLIF is a feasible solution for lumbar spinal reconstruction to maximize direct and indirect decompression of the neuroforamina and central spinal canal in patients with lumbar degenerative diseases and low-grade spondylolisthesis.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part II: Consecutive Case Series.

BACKGROUND: Advances in operative techniques and instrumentation technology have evolved to maximize patient outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). The transfacet MIS-TLIF is a modified approach to the standard MIS-TLIF that leverages a bony working corridor to access the disc space for discectomy and interbody device placement. OBJECTIVE: To evaluate clinical and radiographic results following transfacet MIS-TLIF using an expandable interbody device. METHODS: We performed a retrospective review of consecutive patients who underwent transfacet MIS-TLIF for degenerative lumbar spondylolisthesis. Patient-reported outcome measures for pain and disability were assessed. Sagittal lumbar segmental parameters and regional lumbopelvic parameters were assessed on upright lateral radiographs obtained preoperatively and during follow-up. RESULTS: A total of 68 patients (61.8% male) underwent transfacet MIS-TLIF at 74 levels. The mean age was 63.4 yr and the mean follow-up 15.2 mo. Patients experienced significant short- and long-term postoperative improvements on the numeric rating scale for low back pain (-2.3/10) and Oswestry Disability Index (-12.0/50). Transfacet MIS-TLIF was associated with an immediate and sustained reduction of spondylolisthesis, and an increase in index-level disc height (+0.71 cm), foraminal height (+0.28 cm), and segmental lordosis (+6.83°). Patients with preoperative hypolordosis (<40°) experienced significant increases in segmental (+9.10°) and overall lumbar lordosis (+8.65°). Pelvic parameters were not significantly changed, regardless of preoperative alignment. Device subsidence was observed in 6/74 (8.1%) levels, and fusion in 50/53 (94.3%) levels after 12 mo. CONCLUSION: Transfacet MIS-TLIF was associated with clinical improvements and restoration of radiographic sagittal segmental parameters. Regional alignment correction was observed among patients with hypolordosis at baseline.

Time-of-flight magnetic resonance angiography imaging of a residual arteriovenous malformation nidus after Onyx embolization for stereotactic radiosurgery planning. Technical note.

This report demonstrates that time-of-flight (TOF) MR angiography is a useful adjunct for planning stereotactic radiosurgery (SRS) of large arteriovenous malformations (AVMs) after staged embolization with Onyx. Onyx (ethylene vinyl copolymer), a recently approved liquid embolic agent, has been increasingly used to exclude portions of large AVMs from the parent circulation prior to SRS. Limiting SRS to regions of persistent arteriovenous shunting and excluding regions eliminated by embolization may reduce unnecessary radiation doses to eloquent brain structures. However, SRS dosimetry planning presents unique challenges after Onyx embolization because it creates extensive artifacts on CT scans, and it cannot be delineated from untreated nidus on standard MR sequences. During the radiosurgery procedure, MR images were obtained using a GE Signa 1.5-T unit. Standard axial T2 fast spin echo high-resolution images (TR 3000 msec, TE 108 msec, slice thickness 2.5 mm) were generated for optimal visualization of brain tissue and AVM flow voids. The 3D TOF MR angiography images of the circle of Willis and vertebral arteries were subsequently obtained to visualize AVM regions embolized with Onyx (TR 37 msec, TE 6.9 msec, flip angle 20 degrees). Adjunct TOF MR angiography images demonstrated excellent contrast between nidus embolized with Onyx and regions of persistent arteriovenous shunting within a large AVM prior to SRS. Additional information derived from these sequences resulted in substantial adjustments to the treatment plan and an overall reduction in the treated tissue volume.

Validation of the Disabilities of the Arm, Shoulder, and Hand in Patients Undergoing Cervical Spine Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the performance and convergent validity of the disabilities of the arm, shoulder, and hand (DASH) in comparison with the visual analog scale (VAS) for pain, and neck disability index (NDI) in patients undergoing cervical spine surgery. SUMMARY OF BACKGROUND DATA: Neck-specific disability scales do not adequately assess concurrent upper extremity involvement in patients with cervical spine disorders. The DASH is a patient-reported outcomes (PRO) instrument designed to measure functional disability due to upper extremity conditions but has additionally been shown to perform well in patients with neck disorders. METHODS: We identified patients who underwent cervical spine surgery at our institution between 2013 and 2016. We collected demographic information, clinical characteristics, and PRO measures-DASH, VAS, NDI-preoperatively, as well as early and late postoperatively. We calculated descriptive statistics and changes from baseline in PROs. Correlation coefficients were used to quantify the association between PRO measures. The analysis was stratified by radiculopathy and myelopathy diagnoses. RESULTS: A total of 1046 patients (52.8% male) with PROs data at baseline were included in the analysis. The mean age at surgery ±â€ŠSD was 57.2 ±â€Š11.3 years, and postoperative follow-up duration 12.7 ±â€Š10.7 months. The most common surgical procedure was anterior cervical discectomy and fusion (71.1%). Patients experienced clinically meaningful postoperative improvements in all PRO measures. The DASH showed moderate positive correlations with VAS preoperatively (Spearman rho = 0.43), as well as early (rho = 0.48) and late postoperatively (rho = 0.60). DASH and NDI scores were strongly positively correlated across operative states (Preoperative rho = 0.74, Early Postoperative rho = 0.78, Late Postoperative rho = 0.82). Stratified analysis by preoperative diagnosis showed similar within-groups trends and pairwise correlations. However, radiculopathy patients experienced larger magnitude early and late change scores. CONCLUSION: The DASH is a valid and responsive PRO measure to evaluate disabling upper extremity involvement in patients undergoing cervical spine surgery. LEVEL OF EVIDENCE: 3.

Spinal Fusion for Pediatric Spondylolisthesis: National Trends, Complications, and Short-Term Outcomes.

BACKGROUND: Current surgical management guidelines for pediatric spondylolisthesis (PS) are reliant on data from single-center cohorts. OBJECTIVE: To analyze national trends and predictors of short-term outcomes in spinal fusion surgery for PS by performing a retrospective cross-sectional analysis of the Kids' Inpatient Database (KID). METHODS: The KID (sampled every 3 yr) was queried from 2003 to 2012 to identify all cases (age 5-17) of spinal fusion for PS (n = 2646). We analyzed trends in patient characteristics, surgical management, and short-term outcomes. Both univariate and multivariable analyses were utilized. RESULTS: The 2646 spinal fusions for PS included posterior-only fusions (86.8%, PSF), anterior lumbar interbody fusions (4.8%, ALIF), and combined anterior and posterior fusions (8.4%, APLF) procedures. The utilization of APLF decreased over time (9.9%-6.4%, P = .023), whereas the number of total spinal fusions and the proportion of PSF and ALIF procedures have not changed significantly. Uptrends in Medicaid insured individuals (1.2%-18.9%), recombinant human bone morphogenetic protein-2 insertion (8.8%-16.6%), decompression (34.7%-42.8%), and mean inflation-adjusted hospital costs ($21 855-$32 085) were identified (all P < .001). In multivariable analysis, Medicaid status (odds ratio [OR] = 1.93, P = .004), teaching hospitals (OR = 1.94, P = .01), decompression (OR = 1.78, P = .004), and the APLF procedure (OR = 2.47, P = .001) increased the likelihood of complication occurrence (all P < .001). CONCLUSION: The addition of decompression during fusion and the APLF procedure were associated with more in-hospital complications, though this may have been indicative of greater surgical complexity. The utilization of the APLF procedure has decreased significantly, while costs associated with the treatment of PS have increased over time.

Population-based approaches to treatment and readmission after spinal cord injury.

BACKGROUND: Recent studies in surgical and non-surgical specialties have suggested that patients admitted on the weekend may have worse outcomes. In particular, patients with stroke and acute cardiovascular events have shown worse outcomes with weekend treatment. It is unclear whether this extends to patients with spinal cord injury (SCI). This study was designed to evaluate factors for readmission after index hospitalization for spinal cord injury. METHODS: This cohort was constructed from the State Inpatient Databases of California, New York, and Florida. For this study 14,396 patients with SCI were identified. The primary outcome measure evaluated was 30-day readmission. Secondary measures include in-hospital complications. Univariate and multivariate analysis were utilized to evaluate covariates. c2, Fisher's exact, and linear, logistic, and modified Poisson regression methods were utilized for statistical analysis. Propensity score methods were used with matched pairs analysis performed by the McNemar's Test. RESULTS: Weekend admission was not associated with increased 30- day readmission rates in multivariate analysis. Race and discharge to a facility (RR 1.60 [1.43-1.79]) or home with home care (RR 1.23 [1.07-1.42]), were statistically significant risk factors for readmission. Payor status did not affect rates of readmission. In propensity score matched pairs analysis, weekend admission was not associated with increased odds of 30-day readmission (OR 1.04 [0.89-1.21]). Patients admitted to high volume centers had significantly lower risk of readmission when compared with patients admitted to low volume centers. CONCLUSIONS: Our results suggest that the weekend effect, described previously in other patient populations, may not play as important a role in patients with SCI.

Fractional anisotropy to quantify cervical spondylotic myelopathy severity.

BACKGROUND: A number of clinical tools exist for measuring the severity of cervical spondylotic myelopathy (CSM). Several studies have recently described the use of non-invasive imaging biomarkers to assess severity of disease. These imaging markers may provide an additional tool to measure disease progression and represent a surrogate marker of response to therapy. Correlating these imaging biomarkers with clinical quantitative measures is critical for accurate therapeutic stratification and quantification of axonal injury. METHODS: Fourteen patients and seven healthy control subjects were enrolled. Patients were classified as mildly (7) or moderately (7) impaired based on Modified Japanese Orthopedic Association Scale. All patients underwent diffusion tensor imaging (DTI) and diffusion basis spectrum imaging (DBSI) analyses. In addition to standard neurological examination, all participants underwent 30-m Walking Test, 9-hole Peg Test (9HPT), grip strength, key pinch, and vibration sensation thresholds in the index finger and great toe. Differences in assessment scores between controls, mild and moderate CSM patients were correlated with DTI and DBSI derived fractional anisotropy (FA). RESULTS: Clinically, 30-meter walking times were significantly longer in the moderately impaired group than in the control group. Maximum 9HPT times were significantly longer in both the mildly and moderately impaired groups as compared to normal controls. Scores on great toe vibration sensation thresholds were lower in the mildly impaired and moderately impaired groups as compared to controls. We found no clear evidence for any differences in minimum grip strength, minimum key pinch, or index finger vibration sensation thresholds. There were moderately strong associations between DTI and DBSI FA values and 30-meter walking times and 9HPT. CONCLUSIONS: The 30-m Walking Test and 9HPT were both moderately to strongly associated with DTI/DBSI FA values. FA may represent an additional measure to help differentiate and stratify patients with mild or moderate CSM.