Preoperative Segmental Lordosis Research Articles

Is multilevel MIS-TLIF with bilateral facetectomy a lordosing procedure? A retrospective cohort of 3-level MIS-TLIF.

Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a common surgery that has been extensively reported. However, publications on 3-level MIS-TLIF are sparse, and the effects of multilevel MIS-TLIF on sagittal balance remain controversial. This study aimed to analyze the outcomes and variables involved in the correction of sagittal imbalance by multilevel MIS-TLIF. Consecutive patients who underwent 3-level MIS-TLIF were retrospectively analyzed. Demographics and clinical outcomes were evaluated. Standard radiological and spinopelvic parameters were measured pre- and postoperatively, and at the last follow-up. A linear regression model was used to examine the correlation between preoperative segmental lordosis (SL) and the degree of sagittal correction. An optimal cutoff of preoperative SL to predict the change in sagittal correction was determined by receiver operating characteristic (ROC) analysis. Forty-seven patients (mean follow-up 24.63 ± 12.69 months) were included. Postoperatively, all patients showed clinical improvements, demonstrated by the Oswestry Disability Index and visual analog scale. The overall SL at the last follow-up was slightly nonsignificantly increased (1.23°, p = 0.267), while the other spinopelvic parameters, including lumbar lordosis (p = 0.008), sacral slope (p < 0.001), pelvic tilt (p = 0.002), and pelvic incidence-lumbar lordosis mismatch (p = 0.006), all improved significantly compared with preoperatively. The preoperative SL was negatively correlated with the change in SL at the last follow-up (r2 = 0.2591, p = 0.0003), and the cutoff value was 26.89° (area under the ROC curve = 0.7836, p = 0.0087). The 24 patients who had a less lordotic lumbar spine (i.e., preoperative SL ≤ 27°) demonstrated significant improvement in spinopelvic parameters, whereas the other 23 patients (SL > 27°) had a slight, insignificant decrease of spinopelvic parameters. Multilevel MIS-TLIF improved sagittal balance and SL with satisfactory patient-reported clinical outcomes at 2 years postoperatively. Multilevel MIS-TLIF was more effective in increasing lordosis in patients whose lumbar spine had a smaller preoperative lordotic curve (SL ≤ 27°).

The analysis of segmental lordosis restored by oblique lumbar interbody fusion and related factors: building up preoperative predicting model

BackgroundOblique lumbar interbody fusion (OLIF) procedures have the potential to increase the segmental lordosis by inserting lordotic cages, however, the amount of segmental lordosis (SL) changes can vary and is likely influenced by several factors, such as patient characteristics, radiographic parameters, and surgical techniques. The objective of this study was to analyze the impact of related factors on the amount of SL changes in OLIF procedures and to build up predictive model for SL changes.MethodsThis is a retrospective study involving prospectively enrolled patients. A total of 119 patients with 174 segments undergoing OLIF procedure were included and analyzed. The lordotic cages used in all cases had 6-degree angle. Radiographic parameters including preoperative and postoperative segmental disc angle (SDA, preSDA and postSDA), SDA changes on flexion-extension views (ΔSDA-FE), CageLocation and CageInclination were measured by two observers. Interobserver reliability of measurements were ensured by analysis of interclass correlation coefficient (ICC > 0.75). Pearson correlation coefficient analysis and multivariate linear regression were employed to identify factors related to SDA changes and to build up predictive model for SDA changes.ResultsThe average change of segmental disc angle (ΔSDA, postSDA-preSDA) was 3.9° ± 4.8° (95% confidence interval [CI]: 3.1°-4.6°) with preSDA 5.3° ± 5.0°. ΔSDA was 10.8° ± 3.2° with negative preSDA (kyphotic), 5.0° ± 3.7° with preSDA ranging from 0° to 6°, and 1.0° ± 4.1° with preSDA> 6°. Correlation analysis revealed a significant negative correlation between ΔSDA and preSDA (r = − 0.713, P < 0.001), CageLocation (r = − 0.183, P = 0.016) and ΔSDA-FE (r = − 0.153, P = 0.044). In the multivariate linear regression, preSDA and CageLocation were included in the predictive model, resulting in minimal adjusted R2 change (0.017) by including CageLocation. Therefore, the recommended predictive model was ΔSDA = 7.9–0.8 × preSDA with acceptable fit. (adjusted R2 = 0.508, n = 174, P < 0.001).ConclusionsThe restoration of segmental lordosis through OLIF largely depends on the preoperative segmental lordosis. The predictive model, which utilized preoperative segmental lordosis, facilitates preoperative planning for corrective surgery using the OLIF procedure.

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

Retrospective Case-Series. 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. 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. 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 (β = -.45° P = .001, β = 15.06° P < .001, respectively). 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.

Comparison of segmental lordosis gain of prone transpsoas (PTP) vs. lateral lumbar interbody fusion.

Lumbar interbody fusion is a standard method to treat certain degenerative conditions that are refractory to conservative treatments. LLIF reduces posterior muscle damage, can relieve neurological symptoms through indirect decompression, provides increased stability with its wider cages, and promotes more significant segmental lordosis than standard posterior techniques. However, the technique possesses its issues, such as unusual positioning, possible plexus-related symptoms, and median segmental lordosis correction. Trying to ease those issues, the idea of a prone transpsoas technique occurred. Retrospective, single-centric, comparative, and non-randomized study. The authors paired patients receiving lateral lumbar interbody fusion (LLIF) or prone transpsoas (PTP) to evaluate the technique's impact on the segmental lordosis correction. A correlation test selected the covariates for the matching. p-Values inferior to 0.05 were deemed significant. Seventy-one patients were included in the analysis, 53 in the LLIF group and 18 in the PTP group. The significant covariates to the segmental lordosis correction were technique, preoperative segmental lordosis, cage position, and preoperative pelvic tilt. After the paring model, PTP showed significant segmental lordosis correction potential regarding the LLIF. The prone transpsoas approach can significantly enhance the correction of segmental lordosis proportionated to the traditional LLIF approach.

Impact of the Preoperative Spinopelvic Parameters on the Segmental Lordosis Correction after One-level Lateral Lumbar Interbody Fusion.

Objectives The present study aimed to assess whether preoperative spinopelvic parameters can influence the gain of segmental lordosis after one level of lateral lumbar interbody fusion. Methods The following radiological parameters were measured in the X-rays: pelvic incidence, lumbar lordosis, pelvic tilt, L4S1 lordosis, index level segmental lordosis, intraoperative index segmental lordosis, pelvic mismatch (IP-LL), distal lordosis proportion, delta segmental lordosis, Pelvic Titlt (PT) > 20, actual sacral slope, and ideal sacral slope, and the correlation of these variables with the gain of segmental lordosis was investigated. Afterwards, an exploratory cluster analysis was performed to identify common characteristics between patients and segmental lordosis gain. Results The sample of the present study comprised 104 patients, of which 76% presented segmental lordosis gain. The most correlated parameters with the segmental lordosis gain were preoperative segmental lordosis (−0.50) and delta intraoperative lordosis (0.51). Moreover, patients in the high PI groups had a trend to gain more segmental lordosis ( p < 0.05) and a reduced risk of losing segmental lordosis (Odds 6.08). Conclusion Patients with low-medium PI profiles presented higher odds of loss of segmental lordosis. However, the preoperative spinopelvic parameters alone do not seem to play a significant role in the fate of segmental lordosis gain.

Pear-Shaped Disk as a Risk Factor for Intraoperative End Plate Injury in Oblique Lumbar Interbody Fusion

Intraoperative end plate injury can result in late-onset cage subsidence in oblique lumbar interbody fusion (OLIF). This study aimed to identify risk factors for intraoperative end plate injury and investigate whether a pear-shaped disk correlated with intraoperative end plate injury in OLIF. We retrospectively reviewed 102 levels in 82 patients (mean age 60.1 ± 10.0 years) who underwent OLIF for degenerative lumbar diseases. Intraoperative end plate injury was evaluated using midline sagittal computed tomography views at 3 days postoperatively and defined as cage breaching into an adjacent cortical end plate >2 mm. Patient demographics, surgical parameters, radiographic parameters, and cage-related parameters were recorded in all surgical levels. Evaluation of risk factors associated with intraoperative end plate injury was performed. Patient-reported outcome, fusion status, and late-onset cage subsidence were analyzed at a minimum of 1 year after the surgery. Intraoperative end plate injury was observed in 26 levels (25.5%). Multivariate logistic regression analysis identified that bone mineral density (odds ratio [OR]= 0.978), preoperative segmental lordosis (OR= 0.790), and pear-shaped disk were risk factors (OR= 5.837) for intraoperative end plate injury. Intraoperative end plate injury occurred in 45.5% of levels with a pear-shaped disk compared with 16.0% of levels with no pear-shaped disk (P < 0.01). Late-onset cage subsidence was significantly more frequent in the injury group than the no-injury group. Patient-reported outcome and fusion status were unrelated to intraoperative end plate injury. A pear-shaped disk is the greatest risk factor for intraoperative end plate injury following OLIF.

What Affects Segmental Lordosis of the Surgical Site after Minimally Invasive Transforaminal Lumbar Interbody Fusion?

PurposeThis study was undertaken to identify factors that affect segmental lordosis (SL) after minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) by comparing patients whose postoperative SL increased with those whose decreased.Materials and MethodsFifty-five patients underwent MIS-TLIF at our institute from January 2018 to September 2019. Demographic, pre- and postoperative radiologic, and cage-related factors were included. Statistical analyses were designed to compare patients whose SL increased with decreased after surgery.ResultsAfter surgery, SL increased in 34 patients (group I) and decreased in 21 patients (group D). The index level, disc lordosis, SL, lumbar lordosis, proximal lordosis (PL), and Y-axis position of the cage (Yc) differed significantly between groups I and D. The cage in group I was more anterior than that in group D (Yc: 55.84% vs. 51.24%). Multivariate analysis showed that SL decreased more significantly after MIS-TLIF when the index level was L3/4 rather than L4/5 [odds ratio (OR): 0.46, p=0.019], as preoperative SL (OR: 0.82, p=0.037) or PL (OR: 0.68, p=0.028) increased, and as the cage became more posterior (OR: 1.10, p=0.032).ConclusionChanges in SL after MIS-TLIF appear to be associated with preoperative SL and PL, index level, and Yc. An index level at L4/5 instead of L3/4, smaller preoperative SL or PL, and an anterior position of the cage are likely to result in increased SL after MIS-TLIF.

Does transforaminal lumbar interbody fusion induce lordosis or kyphosis? Radiographic evaluation with a minimum 2-year follow-up.

Conflicting reports exist about whether transforaminal lumbar interbody fusion (TLIF) induces lordosis or kyphosis, ranging from decreasing lordosis by 3.71° to increasing it by 18.8°. In this study, the authors' aim was to identify factors that result in kyphosis or lordosis after TLIF. A single-center, retrospective study of open TLIF without osteotomy for spondylolisthesis with a minimum 2-year follow-up was undertaken. Preoperative and postoperative clinical and radiographic parameters and cage specifics were collected. TLIFs were considered to be "lordosing" if postoperative induction of lordosis was > 0° and "kyphosing" if postoperative induction of lordosis was ≤ 0°. A total of 137 patients with an average follow-up of 52.5 months (range 24-130 months) were included. The overall postoperative disc angle (DA) and segmental lordosis (SL) increased by 1.96° and 1.88° (p = 0.003 and p = 0.038), respectively, whereas overall lumbar lordosis remained unchanged (p = 0.133). Seventy-nine patients had lordosing TLIFs with a mean SL increase of 5.72° ± 3.97°, and 58 patients had kyphosing TLIFs with a mean decrease of 3.02° ± 2.98°. Multivariate analysis showed that a lower preoperative DA, lower preoperative SL, and anterior cage placement were correlated with the greatest increase in postoperative SL (p = 0.040, p < 0.001, and p = 0.035, respectively). There was no difference in demographics, cage type or height, or spinopelvic parameters between the groups (p > 0.05). Linear regression showed that the preoperative DA and SL correlated with SL after TLIF (R2 = 0.198, p < 0.001; and R2 = 0.2931, p < 0.001, respectively). Whether a TLIF induces kyphosis or lordosis depends on the preoperative DA, preoperative SL, and cage position. Less-lordotic segments became more lordotic postoperatively, and highly lordotic segments may lose lordosis after TLIF. Cages placed more anteriorly were associated with more lordosis.

Preoperative Radiographic Prediction Tool for Early Postoperative Segmental and Lumbar Lordosis Alignment After Transforaminal Lumbar Interbody Fusion.

ObjectiveTransforaminal lumbar interbody fusion (TLIF) is a common approach and results in varying degrees of lordosis correction. The purpose of this study is to determine preoperative radiographic spinopelvic parameters that predict change in postoperative segmental and lumbar lordosis after TLIF.Materials & MethodsThis study is a single surgeon retrospective review of one-level and two-level TLIFs from L3-S1. All patients underwent bilateral facetectomies, 10 mm TLIF cage (non-lordotic) insertions, and bilateral pedicle screw-rod construct placements. Pre- and post-operative X-rays were assessed for preoperative segmental lordosis (SL), lumbar lordosis (LL), and pelvic incidence (PI). Univariate and multi-predictor linear regression analyses were performed to determine the relationships between preoperative radiographic findings and change in early postoperative segmental and lumbar lordosis.ResultsNinety-seven patients contributing 128 intervertebral segments were examined. The mean change in SL after TLIF was 7.3 (range: 0.10-28.9°, SD 6.39°). The mean change in LL after TLIF was 5.5˚ (range: -14.8-39.2°, standard deviation (SD) 7.16°). Greater preoperative LL predicted less postoperative LL correction, while greater preoperative PI predicted more postoperative SL and LL correction. Greater anterior disk height was noted to be associated with a decreased change in SL (∆SL). An annular tear on preoperative magnetic resonance imaging (MRI) predicted a 2.7° decrease in ∆SL. A Schmorl's node on preoperative MRI predicted a 4.0° decrease in change in LL (∆LL).ConclusionsA greater preoperative lordosis and a lower spinopelvic mismatch lessen the potential for an increase in the postoperative SL and LL after a TLIF, which is likely due to a ‘ceiling’ effect of an otherwise optimized spinal alignment. A greater anterior disk height and the presence of an annular tear are associated with decreased ∆SL.

Posterior Floating Laminotomy as a New Decompression Technique for Posterior Cervical Spinal Fusion Surgery.

ObjectiveIn the cervical spine, many surgical procedures have been developed to achieve optimal results for various disorders, including degenerative diseases, traumatic injury, and tumor. In this study, we report our experience and follow-up results with a new surgical technique for cervical spine entitled posterior floating laminotomy (PFL) in comparison with conventional laminectomy and fusion (LF). MethodsData for 85 patients who underwent conventional LF (n=66) or PFL (n=19) for cervical spine disorders between 2012 and 2019 were analyzed. Radiological parameters, including cervical lordosis (CL), T1 slope (T1S), segmental lordosis (SL), and C2–7 sagittal vertical axis (SVA), were measured with lateral spine X-rays. Functional outcomes, comprising the modified Japanese Orthopaedic Association (mJOA), neck disability index (NDI), and visual analog scale (VAS) scores, were also measured. For the patients who underwent PFL, postoperative magnetic resonance image (MRI) was performed in a month after the surgery, and the degree of decompression was evaluated at the T2-weighted axial image, and postoperative computed tomography (CT) was conducted immediately and 1 year after the operation to evaluate the gutter fusion. ResultsThere was no difference in CL, T1S, SL, and C2–7 SVA between the groups but there was a difference in the preoperative and postoperative SL angles. The mean difference in the preoperative SL angle compared with that at the last follow-up was -0.3° after conventional LF and 4.7° after PFL (p=0.04), respectively. mJOA, NDI, and VAS scores showed significant improvements (p<0.05) during follow-up in both groups. In the PFL group, postoperative MRI showed sufficient decompression and postoperative CT revealed gutter fusion at 1 year after the operation. ConclusionPFL is a safe surgical method which can preserve postoperative CL and achieve good clinical outcomes.

The minimally invasive interbody selection algorithm for spinal deformity.

Minimally invasive surgery (MIS) for spinal deformity uses interbody techniques for correction, indirect decompression, and arthrodesis. Selection criteria for choosing a particular interbody approach are lacking. The authors created the minimally invasive interbody selection algorithm (MIISA) to provide a framework for rational decision-making in MIS for deformity. A retrospective data set of circumferential MIS (cMIS) for adult spinal deformity (ASD) collected over a 5-year period was analyzed by level in the lumbar spine to identify surgeon preferences and evaluate segmental lordosis outcomes. These data were used to inform a Delphi session of minimally invasive deformity surgeons from which the algorithm was created. The algorithm leads to 1 of 4 interbody approaches: anterior lumbar interbody fusion (ALIF), anterior column release (ACR), lateral lumbar interbody fusion (LLIF), and transforaminal lumbar interbody fusion (TLIF). Preoperative and 2-year postoperative radiographic parameters and clinical outcomes were compared. Eleven surgeons completed 100 cMISs for ASD with 338 interbody devices, with a minimum 2-year follow-up. The type of interbody approach used at each level from L1 to S1 was recorded. The MIISA was then created with substantial agreement. The surgeons generally preferred LLIF for L1-2 (91.7%), L2-3 (85.2%), and L3-4 (80.7%). ACR was most commonly performed at L3-4 (8.4%) and L2-3 (6.2%). At L4-5, LLIF (69.5%), TLIF (15.9%), and ALIF (9.8%) were most commonly utilized. TLIF and ALIF were the most selected approaches at L5-S1 (61.4% and 38.6%, respectively). Segmental lordosis at each level varied based on the approach, with greater increases reported using ALIF, especially at L4-5 (9.2°) and L5-S1 (5.3°). A substantial increase in lordosis was achieved with ACR at L2-3 (10.9°) and L3-4 (10.4°). Lateral interbody arthrodesis without the use of an ACR did not generally result in significant lordosis restoration. There were statistically significant improvements in lumbar lordosis (LL), pelvic incidence-LL mismatch, coronal Cobb angle, and Oswestry Disability Index at the 2-year follow-up. The use of the MIISA provides consistent guidance for surgeons who plan to perform MIS for deformity. For L1-4, the surgeons preferred lateral approaches to TLIF and reserved ACR for patients who needed the greatest increase in segmental lordosis. For L4-5, the surgeons' order of preference was LLIF, TLIF, and ALIF, but TLIF failed to demonstrate any significant lordosis restoration. At L5-S1, the surgical team typically preferred an ALIF when segmental lordosis was desired and preferred a TLIF if preoperative segmental lordosis was adequate.

Preoperative lordosis in L4/5 predicts segmental lordosis correction achievable by transforaminal lumbar interbody fusion.

The mean potential of lordosis restoration by transforaminal lumbar interbody fusion (TLIF) is supposed to be low in general. In contrast, clinical experience shows a wide range of segmental lordosis correction. In this study, the predictability of lordosis correction should be investigated. Prospectively collected register data were analyzed retrospectively. One hundred twenty-one consecutive patients (2014-2016) operated with single-level TLIF L4/5 (10°-lordotic cage). Segmental lordosis (L4/5) and overall lordosis (L1-S1) were measured on lumbar X-rays: preoperatively (pre), after 3-5days (post), at least 24months postoperatively (2yFU). Outcome and satisfaction of patients were assessed. Parameters were statistically compared by students t-tests (a = 0.05). In addition, predictors of correction were analyzed. Age was 60.7years, rate of 2yFU 41.3% (n = 50). Lordosis correction L4/5 was statistically significant with (post-pre) 4.9 ± 5.7° (p < 0.01), but not significant for L1-S1 (post-pre) 1.6 ± 8.0° (p = 0.3). A strong-moderate correlation of lordosis L4/5 (pre) and lordosis correction L4/5 (post-pre) was shown (r = - 0.6, p < 0,01). In a rising range of preoperative lordosis L4/5 from 15-30° the likelihood of lordosis loss increased. In 2yFU correction, L4/5 was significant with (post-pre) 5.4 ± 5.4° (p < 0.01), no significant long-term change (2yFU-postop) - 1.5 ± 4.9° (p = 0.2). No correlation (r = - 0.1) of correction and ODI. VAS-B improved by means of 2.9, VAS-L by 2.5, ODI by 19.1% (pre vs. 2yFU), each statistically significant (p < 0.01). Significant segmental relordosation can be performed by TLIF L4/5. The potential of correction strongly correlates with preoperative lordosis. Therefore, TLIF technique should be considered carefully in cases with a preoperative segmental lordosis of more than 15° and additional need of lordosation.

109. Radiographic predictors of indirect neural decompression in minimally invasive transpsoas lateral interbody fusion

BACKGROUND CONTEXT An advantage of lateral interbody fusion (LLIF) surgery is the resultant indirect decompression of the neural elements that occurs with disc height restoration, restoration of spinal alignment and ligamentotaxis. The degree to which indirect decompression of the spinal canal occurs varies patient to patient, and there remains no method for effectively predicting which patients will or will not respond. PURPOSE In this study, we identify pre- and postoperative predictive factors of radiographic indirect decompression of the central spinal canal. The goal is to help surgeons ascertain which patients best respond to indirect decompression in the setting of lateral interbody fusion. STUDY DESIGN/SETTING This is a retrospective evaluation of a prospectively and consecutively collected cohort of patients treated for degenerative etiologies at a single institution. PATIENT SAMPLE Patients were included if they received a minimally invasive lateral transpsoas interbody fusion by a single surgeon at our institution. Patients were treated for degenerative etiologies. OUTCOME MEASURES A retrospective evaluation of prospectively collected consecutive patients treated with LLIF surgery treated at a single institution without subsequent direct decompression was performed. Pre- and postoperative MRI imaging was used to grade canal stenosis and three-dimensional volumetric reconstructions were used to measure changes in the central canal area (CCA). METHODS Multivariate regression was used to identify predictive variables that correlated with increases in CCA. Independent assessments of canal measurements were made by a blinded board-certified neuroradiologist and a spine surgeon. RESULTS Sixty-six patients with 110 levels were treated with a mean age of 68 years. Forty-six levels (42%) were treated for DDD, 36 levels (33%) for spondylolisthesis, 11 levels (10%) for adjacent segment disease and 17 levels (15%) for deformity. Preoperatively, 19 patients had moderate (29%) and 18 had severe stenosis (27%) with the remainder having mild or no stenosis. Of these 37 patients, only 4 remained severe, 4 were moderate and the rest (78%) improved to mild or no stenosis. CCA increased 41% from a mean of 1.09 to 1.55 cm2 (p 0.05). Multivariate evaluation of predictive variables identified that preoperative anterolisthesis (p=0.002), the presence of vacuum disc phenomenon (p=0.049) and preoperative segmental lordosis (p=0.009) were independently associated with percentage increase in CCA. Age, body mass index, side of approach, pedicle screw fixation, facet grading score, presence of facet effusions, preoperative anterior and posterior disc heights, implant distance from the posterior aspect of the vertebral body and implant height all were not associated (p>0.05). CONCLUSIONS LLIF successfully achieves indirect decompression of the CCA radiographically with a mean change of 41%. Preoperative anterolisthesis on standing films, the presence of vacuum disc phenomenon on computed tomography and preoperative segmental lordosis were independently predictive factors for the percentage increase in CCA that can be achieved. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Retrospective Review of Immediate Restoration of Lordosis in Single-Level Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Comparison of Static and Expandable Interbody Cages.

Sagittal alignment is an important consideration in spine surgery. The literature is conflicted regarding the effect of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) on sagittal parameters and the role of expandable cage technology. To compare lordosis generated by static and expandable cages and to determine what factors affect postoperative sagittal parameters. Preoperative regional lordosis (RL), segmental lordosis (SL), and posterior disc height (PDH) were compared to postoperative values in single-level MI-TLIF performed using expandable or static cages. Patients were stratified based on preoperative SL: low lordosis (<15 degrees), moderate lordosis (15-25 degrees), and high lordosis (>25 degrees). Regression analyses were conducted to determine factors associated with postoperative SL and PDH. Of the 171 patients included, 111 were in the static and 60 in the expandable cohorts. Patients with low preoperative lordosis experienced an increase in SL and maintained RL regardless of cage type. Those with moderate to high preoperative lordosis experienced a decrease in SL and RL with the static cage, but maintained SL and RL with the expandable cage. Although both cohorts showed an increase in PDH, the increase in the expandable cohort was greater. Preoperative SL was predictive of postoperative SL; preoperative SL, preoperative PDH, and cage type were predictive of postoperative PDH. Expandable cages showed favorable results in restoring disc height and maintaining lordosis in the immediate postoperative period. Preoperative SL was the most significant predictor of postoperative SL. Thus, preoperative radiographic parameters and goals of surgery should be important considerations in surgical planning.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

BACKGROUND CONTEXT An important objective of lumbar spine surgery is to improve or restore sagittal alignment, as this is strongly linked to patient satisfaction and surgical outcomes. Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) can impact segmental and regional sagittal parameters. PURPOSE To evaluate if restoration of lordosis in MI-TLIF varies depending on the type of cage. STUDY DESIGN/SETTING Retrospective review of prospectively collected data. PATIENT SAMPLE Patients who underwent single level MI-TLIF with one of the following cages: tritanium oblique (static), expandable articulating (expandable), PEEK oblique (static) and PEEK articulating (static). OUTCOME MEASURES Change in total and segmental lordosis. METHODS Total and segmental lordosis was measured on upright lateral radiographs at two time points: preoperatively and immediate postoperatively. A Kruskall–Wallis test was conducted to compare the operative level (L4–L5vs. L5–S1) and a one-way ANOVA was conducted to compare total and segmental lordosis by type of cage. A 2×4 Mixed ANOVA test was conducted to assess the change in total and segmental lordosis by type of cage. RESULTS A total of 115 cases were included in this study of which 14 had a tritanium oblique cage, 14 had an expandable articulating cage, 30 had a PEEK oblique cage and 57 had a PEEK articulating cage. There was a statistically significant difference between the level operated based on the type of cage, with 78.6% of tritanium oblique group, 42.9% of the expandable articulating group, 83.3% of the PEEK oblique group and 61.4% of the peek articulating group being L4–L5 fusions.The mean preoperative segmental lordosis was significantly different between the types of cages (p=.014), with means of 16.74+5.91 (tritanium oblique), 14.93+5.52 (expandable articulating), 19.07+6.91 (PEEK oblique) and 20.70+6.61 (PEEK articulating) with a significant difference between the expandable articulating and PEEK articulating cages (p=.018) seen on post-hoc multiple comparisons. The mean postoperative segmental lordosis was not significantly different between the types of cages (p=.136), with means of 16.81+4.60 (tritanium oblique), 17.19+4.36 (expandable articulating), 19.80+6.82 (PEEK oblique) and 20.37+6.62 (PEEK articulating). The mean preoperative total lordosis was not significantly different between the types of cages (p=.070), with means of 55.13+11.29 (tritanium oblique), 49.57+11.35 (expandable articulating), 49.70+11.30 (PEEK oblique) and 55.84+12.14 (PEEK articulating). The mean postoperative total lordosis was not significantly different between the types of cages (p=.197), with means of 49.61+10.54 (tritanium oblique), 48.75+12.19 (expandable articulating), 49.10+10.49 (PEEK oblique) and 53.37+9.95 (PEEK articulating).The results of the mixed ANOVA showed that neither the change in segmental lordosis (P=.423), nor the change in total lordosis (P=.213) was statistically different between the types of cages. CONCLUSIONS The type of cage does not affect the change in total or segmental lordosis in MI-TLIF.

Anterior cervical discectomy and fusion surgery versus total disc replacement: A comparative study with minimum of 10-year follow-up

Based on long-term follow-ups, this study was designed to investigate the incidence and risk factors for postoperative adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF) or total disc replacement (TDR) in treating cervical degenerative diseases. Between January 2000 and December 2005, 108 cases undergoing ACDF and 78 undergoing TDR, were enrolled into this study. All medical records were retrospectively collected. Every patient was followed up at least 10 years. Outcome assessment included visual analogue scale (VAS) score, Neck Disability Index (NDI) score, Japanese Orthopaedic Association (JOA) score, and radiographic parameters. Consequently, thirty-eight (35.2%) of 108 cases suffered from ASD in ACDF group, and 26 (33.3%) of 78 cases in TDR group. There was no statistical difference between the two groups regarding ASD incidence, VAS/NDI/JOA score, recovery rate. Logistic regression analysis showed that age (OR = 2.86, 95% CI, 1.58–4.14) and preoperative segmental lordosis (OR = 1.90, 95% CI, 1.05–3.20) were risk factors associated with increased odds of ASD regardless of surgical procedures. On the other hand, preoperative overall lordosis (OR = 0.54, 95% CI, 0.26–0.82) was most likely protective. In conclusion, advanced age and preoperative segmental lordosis were identified as risk factors for postoperative ASD, while preoperative overall lordosis proves to be a protective factor.

Posterior-only Approach With Selective Segmental TLIF for Degenerative Lumbar Scoliosis

Forty-six patients with degenerative lumbar scoliosis, and treated with selective segmental transforaminal lumbar interbody fusion (TLIF), were studied retrospectively. To investigate the surgery outcomes of the posterior-only approach with selective segmental TLIF for the treatment of degenerative lumbar scoliosis. Degenerative lumbar scoliosis usually occurs late in the life of patients with no history of scoliosis. TLIF has been successfully used in the surgical treatment of other degenerative diseases of the lumbar spine. Forty-six patients with degenerative lumbar scoliosis and treated with selective segmental TLIF were studied retrospectively. There were 14 male and 32 female patients, with a mean age of 66.4 years. The indications for TLIF of the motion segment included segmental kyphosis in the lumbar spine, significant vertebral translation in any orientation, segmental instability, and significant upper endplate obliquities of L3 or L4. All the patients were followed for a mean duration of 42 months postoperatively. Radiographic evaluation included Cobb angle of scoliosis, lumbar lordosis angle, and segmental lordosis angle. The clinical outcomes were assessed by means of Japanese Orthopedic Association score and patient satisfaction index. The mean preoperative Cobb angle of 31.7 ± 14.4 degrees was corrected to 10.2 ± 6.5 degrees at the final follow-up (t = 15.262, P < 0.001), and the correction rate was 67.8%. The mean preoperative lumbar lordosis angle of -27.5 ± 12.6 degrees was corrected to -39.3 ± 9.7 degrees (t = 12.165, P < 0.001), and the correction rate was 44.4%. The mean preoperative segmental lordosis angle of -6.5 ± 5.1 degrees in the TLIF segment was increased to -11.6 ± 5.9 degrees, and the correction rate was 80%. Besides, the segmental deformity and vertebral translation were also corrected. The mean preoperative Japanese Orthopedic Association score of 14.1 ± 4.2 was increased to 22.2 ± 4.8 (t = 11.453, P < 0.001), and 81% of patients would undergo this surgery again with the same results. Selective segmental TLIF is helpful in correcting lumbar lordosis, segmental deformity, and translation, and thus obtaining satisfactory outcome in the treatment of degenerative lumbar scoliosis.

Adjacent Segment Degeneration After Lumbar Interbody Fusion With Percutaneous Pedicle Screw Fixation for Adult Low-Grade Isthmic Spondylolisthesis: Minimum 3 Years of Follow-up

Although favorable clinical outcomes have been reported for instrumented lumbar interbody fusion (LIF), adjacent segment degeneration (ASD) has been reported as a long-term complication after LIF. To investigate ASD after instrumented LIF performed at a single level and only for the homogeneous disease of adult low-grade isthmic spondylolisthesis. A total of 128 patients who had undergone LIF for the treatment of adult low-grade isthmic spondylolisthesis involving the lower lumbar spine at our institution between February 2001 and December 2004 were retrospectively reviewed by chart review and telephone survey. Of them, 103 patients with a minimum of a 36-month follow-up period were enrolled in this study. The mean age was 48.5 years. The average follow-up period was 59 months. Clinical and radiological data related to segmental lordosis (SL), whole lumbar lordosis, sacral slope, pelvic tilt, pelvic incidence, and L1 axis S1 distance were analyzed to identify significant risk factors for ASD. The overall incidence of ASD was 10.6% (11/103). The incidences of radiographic and symptomatic ASD were 8.7% (9/103) and 1.9% (2/103), respectively. All patients improved clinically and functionally during the follow-up period. Postoperative SL, preoperative SL, whole lumbar lordosis, and L1 axis S1 distance were significant risk factors for ASD. Only SL was a significant risk factor for both the preoperative and postoperative states. ASD may occur at a relatively lower incidence in adult low-grade isthmic spondylolisthesis compared with other degenerative lumbar spinal diseases. SL is significantly correlated with ASD, whereas mechanical alterations caused by LIF are less likely to affect the adjacent segment. Restoration of normal SL is important for preventing ASD, and long-term follow-up is necessary.

Effect of intraoperative position used in posterior lumbar interbody fusion on the maintenance of lumbar lordosis

The objective in this study was to compare retrospectively the use of different operating tables with different positions for posterior lumbar interbody fusion (PLIF) and the effect on intraoperative and postoperative lumbar lordosis and segmental lordosis. One hundred seventy-two patients with degenerative disease of the lumbar spine who underwent posterior decompression and PLIF in which a 0 degrees polyetheretherketone cage and pedicle screw fixation were used were evaluated. Ninety-one patients underwent surgery on a Wilson table (Group I) and 81 patients were treated on an OSI Jackson spinal table (Group II). Preoperative standing, intraoperative prone, and postoperative standing lateral radiographs were obtained in each patient. The total lumbar and segmental lordosis were compared and analyzed according to the position in which the patients were placed for their operation. The intraoperative total lumbar lordosis was significantly decreased compared with the preoperative value. The postoperative total lumbar lordosis was similar, however, to the preoperative values in both groups. In Group I, the intraoperative segmental lordosis of L2-3 and L3-4 was significantly decreased compared with the pre-operative segmental lordosis. In Group II, the intraoperative segmental lordosis of L3-4, L4-5, L5-S1, and L4-S1 was significantly decreased compared with the preoperative segmental lordosis. The postoperative segmental lordosis of L4-5 was significantly decreased and L2-3 was significantly increased compared with the preoperative lordosis in both groups. Intraoperative position does not affect postoperative total lumbar lordosis and segmental lordosis in short-segment PLIF of the lumbar spine in a retrospective analysis of the surgical procedure to maintain lordosis.

Revision surgery of the lumbar spine: anterior lumbar interbody fusion followed by percutaneous pedicle screw fixation

The aim of this study was to evaluate the efficacy of anterior lumbar interbody fusion (ALIF) augmented by percutaneous pedicle screw fixation (PSF) for revision surgery in the lumbar spine and to determine the prognostic factors affecting surgical outcomes. The population included 54 consecutively treated patients in whom revision surgery involving ALIF with PSF was performed between 2001 and 2004. There were 22 men and 32 women, whose mean age was 59.5 years (range 25-78 years). The diagnoses prior to revision ALIF were as follows: degenerative disc disease in 25 patients, instability/spondylolisthesis in 15, recurrent disc herniation in seven, and pseudarthrosis in seven. The mean follow-up period was 24 months (range 12-52 months). The mean visual analog scale score for back and leg pain decreased, respectively, from 7.8 to 2.3 and 8.0 to 2.3 (p < 0.001). The mean Oswestry Disability Index score improved from 70 to 25% (p < 0.001). Radiological evidence of fusion was noted in 52 of 54 patients. The mean preoperative segmental lordosis, whole lumbar lordosis, and sacral tilt were 15.2, 35.5, and 28.3 degrees, respectively; these values were significantly increased to 20.4, 40.7, and 31.4degrees, respectively, after revision surgery (p < 0.001). The increase in sacral tilt was positively correlated with improvement in back pain (p = 0.028) and functional status (p = 0.025). The results demonstrate that ALIF followed by PSF can be an effective alternative in revision surgery of the lumbosacral spine in selected cases. Not only can solid fusion be achieved, sagittal alignment can also be restored in the majority of patients.