Differences In Number Of Levels Research Articles

142. Loss of sagittal correction >3 years after adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> The durability of adult spinal deformity (ASD) surgery is key for cost-effective treatment. Malalignment is one of the main reasons for revision surgery. <h3>PURPOSE</h3> To investigate risk factors for loss of correction within the instrumented lumbar spine following ASD surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospective database. <h3>PATIENT SAMPLE</h3> This study included 321 ASD patients with minimum 3 -year follow-up. <h3>OUTCOME MEASURES</h3> L1-S1, L4-S1 and L1-L4 lumbar lordosis. <h3>METHODS</h3> A total of 321 patients who underwent fusion of the lumbar spine (=5 levels, LIV S1/ilium) with a revision-free follow-up =3 years were identified. Patients were stratified by the change in PI-LL from 6 weeks to 3 years postop as Maintained vs Loss > 5°. Those with a loss due to instrumentation failure (broken rod, screw pullout, etc.) were excluded before comparisons. Changes in regional and focal lordosis over time were investigated with repeated measures ANOVA and factor comparison. <h3>RESULTS</h3> Mean age 64 yrs, BMI 28 kg/m², 80% female. The baseline alignment (PI-LL=21±19°, T1PA=26±12°) was corrected to PI-LL=3±13°, and T1PA=18±10° at 3 yrs (mean 3Y follow-up: 45±11m, with 44±11 mo between early and late follow-up). Eighty-two patients (25.5%) lost >5° of PI-LL correction (mean loss 10±5°). After exclusion of patients with instrumentation failure, 52 patients (Loss) with a mean loss of correction of 8.6±2.9 were compared to 222 controls with maintained LL correction. Demographics were similar between groups (age: 63 vs 61 p=0.15; Sex: 78.4% F vs 88.5% p=0.10). There were no significant differences in use of osteotomy, 3CO, and IBF between Loss and Maintained LL (all p >0.1). There was no significant difference in number of levels fused (11 vs 12 p=0.39), rod material (CoCr 59.4% vs 58.8% p=0.34), and BMP use (88.7% vs 84.6% p=0.41) but Loss had less supplemental rod use (5.8% vs 23.4% p=0.004). Comparison between Maintained and Loss revealed a similar PI-LL mismatch at pre-op (16.7±18.7 vs 20.9±18.3 p=0.14) and final postop (1.8±12.5 vs 5.1±14.5 p=0.11) but a significantly smaller PI-LL for Loss at early postop (0.6±12.8 vs -3.5±13.7 p=0.41). Distally, Maintained had a significant improvement in L4-S1 lordosis from preop to early postop (p=0.013), with no significant difference from early to final follow-up. In contrast, patients in the Loss group had no difference in L4-S1 from preop to early postop (p=0.14), but showed a significant loss of correction at 3 years (p <0.001). Proximally, significant increase between pre and early postop in L1-L4 (all p <0.001), with Loss and Maintained reaching similar early postop value (p=0.34). However, from early postop to final follow up, Loss showed a significant decrease in proximal lordosis (p <0.001) while Maintained did not (p=0.08), corresponding with a smaller absolute L1-L4 in the Loss cohort at 3 yrs (p=0.002). Screw orientation showed a significant decrease from early to late follow-up between the L1 and S1 screws for Loss (1.3±4.1 p=0.031), without any changes across the L4-S1 segment (-0.1±2.9 p=0.97). <h3>CONCLUSIONS</h3> Approximately a quarter of patients lose an average of 10° of their 6-week correction by 3 years. Lordosis is lost proximally through the instrumentation (ie, tulip/shank angle shifts and/or rod bending), but lost distally through bone "settling" through the instrumentation itself. The use of supplemental rods and avoiding sagittal overcorrection may help mitigate this loss. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P127. Use of osteotomy techniques in cervical deformity procedures: Are approaches and practices changing over the years?

<h3>BACKGROUND CONTEXT</h3> Cervical deformity (CD) corrective procedures are ever-evolving, along with the field of spine surgery. The goal of this study was to examine whether surgical advancements over the years have improved or changed outcomes, and the overall way in which we approach CD surgery. <h3>PURPOSE</h3> To investigate if operative approach and outcomes of CD have changed over time in respect to surgical advancements. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study of a prospective cervical deformity database. <h3>PATIENT SAMPLE</h3> A total of 123 CD patients (≥18 years) with complete BL and 2Y HRQL and radiographic data were included. Descriptive analysis included demographics, radiographic, and surgical details. Patients were stratified into 2 groups based on DOS: early (Group I-2012-2014) and later (Group II-2015-2019). Osteotomies were grouped using grading by Ames et al. into low grade (LGO): Grade 1 & 2, and high grade (HGO): Grade 6 & 7. UVA and MVA analyzed differences in osteotomy usage and radiographic, surgical and clinical parameters. Significant CD was characterized by extension XR TS-CL >17°. Rigid deformity was defined by a change of <10°difference between flexion and extension XR. <h3>OUTCOME MEASURES</h3> Complications, HRQL (NDI, mJOA, EQ5D). <h3>METHODS</h3> CD patients (≥18 years) with complete BL and 2-year HRQL and radiographic data were included. Descriptive analysis included demographics, radiographic, and surgical details. Patients were stratified into 2 groups based on DOS: early (Group I-2012-2014) and later (Group II-2015-2019). Osteotomies were grouped using grading by Ames et al. into low grade (LGO): Grade 1 & 2, and high grade (HGO): Grade 6 & 7. UVA and MVA analyzed differences in osteotomy usage and radiographic, surgical and clinical parameters. Significant CD was characterized by extension XR TS-CL >17°. Rigid deformity was defined by a change of <10°difference between flexion and extension XR. <h3>RESULTS</h3> There were 123 CD patients that met inclusion criteria (61years, 63%F, 29.0kg/m2, CCI: 1±1.4). Radiographically at baseline, patients presented with: PT: 19.6± 11°; PI: 55±13°; PI-LL: .9±17.4°; SVA:-3±68mm, TS-CL: 39 ±21°; cSVA: 45±26. Surgical details were 7.7± 4 levels fused with a mean EBL of 1031mL. By surgical approach, 46% had a posterior approach, 20% anterior, and 37% combined. Group I had 49 patients, and Group II had 74. Group II had a higher CCI (1.1 vs .8, p=.2) while there were no significant differences in number of levels fused, reoperations, DJK development, or HRQL metrics between groups (p>0.05). Overall, 53% of patients had an osteotomy. Patients in Group II had a lower usage of HGO (9% vs 23%, p<0.05). In patients with significant CD, Group II received less HGO (3% vs 33%, p<0.05). In posterior approaches, controlling for age, BL deformity, and CCI, Group II underwent less HGO .32[.08-1.2] p=.1. Controlling for age, CCI, and BL deformity, Group II had lower usage of HGO in rigid deformity (.197[.04-.97], p<0.05). <h3>CONCLUSIONS</h3> Overtime, patients undergoing cervical deformity surgery received less high-grade osteotomies, even with high grade deformities. Despite operating on a cohort with a greater degree of comorbidity, there was no deterioration in clinical and radiographic outcomes. These findings reflect a better understanding of surgical management and the utility of invasive osteotomies in adult cervical deformity. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

12. Late spinal infections are more common among pediatric vs adult spinal deformity patients

<h3>BACKGROUND CONTEXT</h3> Late-onset postoperative infections after surgical correction of spinal deformity represent an uncommon, but significant complication of spine surgery. The incidence of late infection following posterior spinal fusion (PSF) in pediatric patients with AIS has been reported to be up to 7.5%. However, there is limited literature on late infections following ASD surgery suggesting that this phenomenon may be less frequent in adults. <h3>PURPOSE</h3> The objective of this study is to characterize the incidence, timing, and pathogenic etiology of late spinal infections after instrumentation for spinal arthrodesis in both age groups who present with spinal deformity. <h3>STUDY DESIGN/SETTING</h3> Retrospective review, single institution <h3>PATIENT SAMPLE</h3> Institutional data was retrospectively queried from 2000 to 2015 to identify patients who underwent instrumented PSF. Patients with more than 12 months follow-up, spinal arthrodesis spanning greater than 5 levels, and idiopathic or degenerative spinal pathology were selected for inclusion. A total of 1113 patients met inclusion criteria<b>:</b> 607 pediatric AIS patients and 506 adult spinal deformity patients. Within the pediatric AIS cohort, 76.1% (462/607) were female compared to 70.9% (359/506) within the ASD cohort. Mean follow-up was 3.9 ± 2.86 years for the AIS patients vs 4.6 ± 3.16 years for the ASD patients. <h3>OUTCOME MEASURES</h3> The following outcomes were assessed and were compared by age cohort of less than 21 vs greater than or equal to 21 years: rate of late-onset spinal infection, timing of late-onset spinal infection, and causative microorganism(s) associated with late-onset spinal infections. Demographic and surgical data were also compared between the two cohorts. <h3>METHODS</h3> The individual charts of all patients were personally reviewed by study team members to identify those who went on to develop late spinal infections. We classified late-onset as spinal infections occurring beyond 6 months (180 days) from the index operation. Diagnosis was established on the basis of return to the operating room for intraoperative bacterial cultures and sensitivities, and irrigation and debridement. <h3>RESULTS</h3> A total of 26 (4.29%) AIS patients and 2 (0.4%) ASD patients developed a late postoperative spinal infection (p = 0.01). Average onset of infection was 4.2 years (1.0-11.6) in the AIS group and 4.0 years (0.6-7.3) in the ASD group. There were significant differences in number of levels fused and reported blood loss between the two groups (p <0.001). After controlling for these intraoperative factors, age remained a significantly correlated with onset of late spinal infection (p < 0.001). Cutibacerium acnes and coagulase-negative Staphylococci were the most commonly detected microorganisms for both groups. <h3>CONCLUSIONS</h3> Pediatric patients are at significantly increased risk for late-onset postoperative spinal infections compared to adults. Skin and indolent organisms are the primary identifiable causative agents in both cohorts. Further research on these differences in infection patterns among adolescents and adults may help tailor personalized management protocols. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Comparison of Surgical Outcomes Between Staged and Simultaneous Decompression of Discontinuous Thoracic Ossification of the Ligamentum Flavum: A Retrospective Study

Discontinuous thoracic ossification of the ligamentum flavum (TOLF) is diagnosed according to the number and distribution of involved segments seen on magnetic resonance images. When TOLF causes thoracic myelopathy, surgical intervention for these lesions becomes unavoidable. However, there are few reports on the outcomes of surgery for discontinuous TOLF. The study included 26 patients of mean age 55.0 years who underwent simultaneous (n= 16) or staged (n= 10) decompression of discontinuous TOLF between July 2006 and June 2016. Final neurologic status was evaluated using the modified Japanese Orthopaedic Association (JOA) score. The surgical data and incidence ofcomplications were compared. The mean follow-up duration was 73.3 months. There was no between-group difference in number of levels decompressed or the amount of intraoperative blood loss. There was a significant improvement in the JOA score from 4.0 before surgery to 8.0 postoperatively, with an average recovery rate of 58.3%. The JOA recovery rate was significantly better in the staged group than simultaneous group (68.4% vs. 52.0%, P < 0.05). However, the incidence of complications was similar between the staged and simultaneous groups including for dural tear (1 vs. 6, P= 0.19), cerebrospinal fluid leak (4 vs. 6, P= 1.00), and transient neurologic deterioration (0 vs. 2, P= 0.51). The surgical outcome of staged decompression for discontinuous TOLF seems to be better than that of simultaneous decompression. The complication rates of these 2 strategies are similar.

Does Percutaneous Lumbosacral Pedicle Screw Instrumentation Prevent Long-Term Adjacent Segment Disease after Lumbar Fusion?

Study DesignRetrospective cohort study.PurposeTo assess long-term clinical outcomes of adjacent segment disease (ASD) in patients who underwent lumbar interbody fusion with percutaneous pedicle screw (PS) instrumentation.Overview of LiteratureASD is a well-known sequela of spinal fusion, and is reported to occur at a rate of 2%–3% per year. There is debate as to whether ASD is a result of the instrumentation and fusion method or is the natural history of the patient’s disease. Minimally invasive percutaneous PS augmentation of lumbar interbody fusion aims to prevent the disruption of posterior soft tissue stabilizers.MethodsFrom 2004–2014, 419 consecutive patients underwent anterior, lateral, or minimally invasive transforaminal lumbar interbody fusion with percutaneous PS placement at a single institution. The mean follow-up was 4.5 years. The primary outcome measure was reoperation due to ASD. Patients were divided into two cohorts: those who underwent revision surgery secondary to ASD and those who did not require further surgery. Radiographic parameters were performed using postoperative radiographs. Patients with a pelvic incidence–lumbar lordosis (PI–LL) mismatch >10° were noted.ResultsRevision proportion secondary to ASD was 4.77% (n=20). Mean time to revision surgery was 2.5 years. Revision rate secondary to ASD was 1.1% per year. Patients who developed ASD were younger than those who did not (50.5 vs. 56.9 years, p=0.015). There was no difference in number of levels fused between cohorts. Revision proportion secondary to ASD was similar between approaches (anterior, lateral, minimally invasive). There was no significant difference in PI–LL mismatch between those who underwent revision for ASD and those who did not (22.2% vs. 18.8%, p=0.758).ConclusionsASD rates in patients who underwent percutaneous PS placement were lower than those previously published after open PS placement, possibly related to greater preservation of the posterior stabilizing elements of the lumbar spine.

Crossing the Cervicothoracic Junction in Posterior Cervical Decompression and Fusion: A Cohort Analysis

The cervicothoracic junction (CTJ) has often been identified as an area of biomechanical vulnerability; however, few studies have examined the relative merits of extending fusions across this area. In this study, we sought to investigate the tradeoffs involved in fusing across the CTJ in cases of elective posterior cervical laminectomy and fusion. We conducted a single-institution retrospective cohort study of patients undergoing elective, multilevel, posterior cervical decompression and fusion for degenerative cervical stenosis. Data were collected on baseline clinical and radiographic variables as well any subsequent complications or reoperations. Outcomes measures were compared between those who received fusion stopping at C7 with those who received fusion crossing the CTJ, with multivariate logistic regression used to adjust for any known confounders. Patients whose fusion crossed the CTJ were found to have more levels fused (mean: 5.8 vs. 3.5 levels, P < 0.0001), longer surgical times (mean: 216 vs. 149 minutes, P < 0.0001), and higher estimated blood losses (mean: 475 vs. 116 mL, P < 0.0001) despite no significant differences in number of levels decompressed (mean: 4.2 vs. 4.3 levels, P= 0.63). The groups did not differ in overall reoperation rate (10.8% vs. 9.4%, P= 1.00), but crossing the CTJ was associated with a higher rate of wound dehiscence (7.8% vs. 0%, P= 0.03). This difference persisted in multivariate analysis (P < 0.001). Crossing the CTJ was associated with increased surgical time, estimated blood loss, and the rates of wound dehiscence. These tradeoffs should be considered in planning posterior cervical decompression and fusion procedures.

Verification of BD Vacutainer® Barricor™ plasma blood collection tube

The cervicothoracic junction (CTJ) has often been identified as an area of biomechanical vulnerability; however, few studies have examined the relative merits of extending fusions across this area. In this study, we sought to investigate the tradeoffs involved in fusing across the CTJ in cases of elective posterior cervical laminectomy and fusion.We conducted a single-institution retrospective cohort study of patients undergoing elective, multilevel, posterior cervical decompression and fusion for degenerative cervical stenosis. Data were collected on baseline clinical and radiographic variables as well any subsequent complications or reoperations. Outcomes measures were compared between those who received fusion stopping at C7 with those who received fusion crossing the CTJ, with multivariate logistic regression used to adjust for any known confounders.Patients whose fusion crossed the CTJ were found to have more levels fused (mean: 5.8 vs. 3.5 levels, P < 0.0001), longer surgical times (mean: 216 vs. 149 minutes, P < 0.0001), and higher estimated blood losses (mean: 475 vs. 116 mL, P < 0.0001) despite no significant differences in number of levels decompressed (mean: 4.2 vs. 4.3 levels, P = 0.63). The groups did not differ in overall reoperation rate (10.8% vs. 9.4%, P = 1.00), but crossing the CTJ was associated with a higher rate of wound dehiscence (7.8% vs. 0%, P = 0.03). This difference persisted in multivariate analysis (P < 0.001).Crossing the CTJ was associated with increased surgical time, estimated blood loss, and the rates of wound dehiscence. These tradeoffs should be considered in planning posterior cervical decompression and fusion procedures.

Delta-tilde interpretation of standard linear mixed model results

We utilize the close link between Cohen’s d, the effect size in an ANOVA framework, and the Thurstonian (Signal detection) d-prime to suggest better visualizations and interpretations of standard sensory and consumer data mixed model ANOVA results. The basic and straightforward idea is to interpret effects relative to the residual error and to choose the proper effect size measure. For multi-attribute bar plots of F-statistics this amounts, in balanced settings, to a simple transformation of the bar heights to get them transformed into depicting what can be seen as approximately the average pairwise d-primes between products. For extensions of such multi-attribute bar plots into more complex models, similar transformations are suggested and become more important as the transformation depends on the number of observations within factor levels, and hence makes bar heights better comparable for factors with differences in number of levels. For mixed models, where in general the relevant error terms for the fixed effects are not the pure residual error, it is suggested to base the d-prime-like interpretation on the residual error. The methods are illustrated on a multifactorial sensory profile data set and compared to actual d-prime calculations based on Thurstonian regression modeling through the ordinal package. For more challenging cases we offer a generic “plug-in” implementation of a version of the method as part of the R-package SensMixed. We discuss and clarify the bias mechanisms inherently challenging effect size measure estimates in ANOVA settings.