Transforaminal Lumbar Interbody Fusion Procedure Research Articles

Correlation Between Cage Positioning and Lumbar Lordosis in Transforaminal Lumbar Interbody Fusion (TLIF).

Objective The present study evaluates radiographic outcomes and the lumbar lordosis achieved with a transforaminal lumbar interbody fusion (TLIF) arthrodesis technique according to the positioning of an interbody device (cage) in the disc space. Methods This is a retrospective radiographic analysis of single-level surgical patients with degenerative lumbar disease submitted to a TLIF procedure and posterior pedicle instrumentation. We divided patients into two groups according to cage positioning. For the TLIF-A group, the cages were anterior to the disc space; for the TLIF-P group, cages were posterior to the disc space. Considering the superior vertebral plateau of the lower vertebra included in the instrumentation, cages occupying a surface equal to the anterior 50% of the midline were placed in the TLIF-A group, and those in a posterior position were placed in the TLIF-P group. We assessed pre- and postoperative orthostatic lateral radiographs to obtain the following measures: lumbar lordosis (LL) (angle L1–S1), segmental lordosis (LS) (L4–S1), and segmental lordosis of the cage (SLC). Results The present study included 100 patients from 2011 to 2018; 44 were males, and 46 were females. Their mean age was 50.5 years old (range, 27 to 76 years old). In total, 43 cages were “anterior” (TLIF-A) and 57 were “posterior” (TLIF-P). After surgery, the mean findings for the TLIF-A group were the following: LL, 50.7°, SL 34.9°, and SLC 21.6°; in comparison, the findings for the TLIF-P group were the following: LL, 42.3° ( p < 0.01), SL 30.7° ( p < 0.05), and SLC 18.8° ( p > 0.05). Conclusion Cage positioning anterior to the disc space improved lumbar and segmental lordosis on radiographs compared with a posterior placement.

Do racial disparities exist in a spine surgery practice that serves a predominately minority population? Outcomes of transforaminal lumbar interbody fusion: A retrospective review

BackgroundRacial minority status is associated with inferior peri-operative outcomes following spinal fusion. Findings have largely been reported within institutions serving few minority patients. This study aimed to identify if racial disparities exist for transforaminal lumbar interbody fusion (TLIF) procedures within an urban academic medical center which serves a majority non-White population. MethodsThis is a retrospective review of patients who underwent a TLIF procedure at our institution between 06/2016-10/2019. Primary outcome measures included length of stay (LOS), discharge disposition, 30-day return to the emergency department (ED), 30-day readmission rate, and 30-day complication rates. One-hundred-fifty-six patients (female: male, 99: 57) met inclusion criteria. Demographic and clinical data (body mass index (BMI), comorbidities, preoperative lab values) were compared. ResultsThe mean LOS was 6.2, 5.9, and 6 days in the White, Hispanic, and Black cohorts, respectively (p = 0.92). There were no differences in discharge disposition between groups (p = 0.52). Thirty-day post-operative complication rates did not differ between groups (p > 0.07). Readmission rates did not differ between groups (p > 0.05). ED visits were more prevalent in the Hispanic group with 16 visits as compared to 8 and 4 in the White and Black groups respectively (p = 0.01). ConclusionsWe found no racial disparities in terms of LOS, discharge disposition, or 30-day readmission rates. Hispanic patients demonstrated an increased utilization of the ED in the early post-operative period. Efforts to overcome language barriers, communicate instructions clearly, and outline post-operative expectations and plans may prevent the need for post-operative ED visits.

Biomechanical Evaluation of Transforaminal Lumbar Interbody Fusion with Coflex-F and Pedicle Screw Fixation: Finite Element Analysis of Static and Vibration Conditions.

ObjectiveTo investigate the biomechanics of transforaminal lumbar interbody fusion (TLIF) with interspinous process device (IPD) or pedicle screw fixation under both static and vibration conditions by the finite element (FE) method.MethodA validated FE model of the L1‐5 lumbar spine was used in this study. This FE model derived from computed tomography images of a healthy female adult volunteer of appropriate age. Then the model was modified to simulate L3‐4 TLIF. Four conditions were compared: (i) intact; (ii) TLIF combined with bilateral pedicle screw fixation (BPSF); (iii) TLIF combined with U‐shaped IPD Coflex‐F (CF); and (iv) TLIF combined with unilateral pedicle screw fixation (UPSF). The intact and surgical FE models were analyzed under static and vibration loading conditions respectively. For static loading conditions, four motion modes (flexion, extension, lateral bending, and axial rotation) were simulated. For vibration loading conditions, the dynamic responses of lumbar spine under sinusoidal vertical load were simulated.ResultUnder static loading conditions, compared with intact case, BPSF decreased range of motion (ROM) by 92%, 95%, 89% and 92% in flexion, extension, lateral bending and axial rotation, respectively. While CF decreased ROM by 87%, 90%, 69% and 80%, and UPSF decreased ROM by 84%, 89%, 66% and 82%, respectively. Compared with CF, UPSF increased the endplate stress by 5%–8% in flexion, 7%–10% in extension, 2%–4% in lateral bending, and decreased the endplate stress by 16%–19% in axial rotation. Compared with CF, UPSF increased the cage stress by 9% in flexion, 10% in extension, and decreased the cage stress by 3% in lateral bending, and 13% in axial rotation. BPSF decreased the stress responses of endplates and cage compared with CF and UPSF. Compared BPSF, CF decreased the facet joint force (FJF) by 6%–13%, and UPSF decreased the FJF by 4%–12%. During vibration loading conditions, compared with BPSF, CF reduced maximum values of the FJF by 16%–32%, and vibration amplitudes by 22%–35%, while UPSF reduced maximum values by 20%–40%, and vibration amplitudes by 31%–45%.ConclusionCompared with other surgical models, BPSF increased the stability of lumbar spine, and also showed advantages in cage stress and endplate stress. CF showed advantages in IDP and FJF especially during vertical vibration, which may lead to lower risk of adjacent segment degeneration. CF may be an effective alternative to pedicle screw fixation in TLIF procedures.

Comparing Patient-Reported Outcomes in Patients Undergoing Lumbar Fusion for Isthmic Spondylolisthesis with Predominant Back Pain versus Predominant Leg Pain Symptoms

To compare patient-reported outcome measures (PROMs) and minimum clinically important difference (MCID) achievement following anterior or transforaminal lumbar interbody fusion for isthmic spondylolisthesis in patients presenting with predominant back pain versus predominant leg pain symptoms. A single-surgeon database was reviewed for anterior or transforaminal lumbar interbody fusion procedures for isthmic spondylolisthesis. Patient demographics, perioperative characteristics, postoperative complications, and PROMs were collected. Demographic/perioperative characteristics were compared among groups using χ2 and Student t tests for categorical and continuous variables, respectively. Mean PROM scores were compared using an unpaired Student t test. Postoperative improvement from preoperative baseline within each cohort was assessed with paired-samples t test. MCID achievement rates were compared with χ2 analysis. In total, 143 patients were included with 65 patients in the predominant back pain and 78 patients in the predominant leg pain cohort. Preoperative visual analog scale (VAS) leg was noted to be significantly greater in predominant leg pain cohort (P < 0.001). Cohorts demonstrated significant mean postoperative differences for the following PROMs at the following postoperative time points: significant differences were noted between cohorts for rate of achievement of MCID for the following PROMs at the following time points: VAS back at 2 years and VAS leg at 6 weeks/12 weeks/6 months/overall (P < 0.036, all). Compared with patients presenting for surgery with predominant leg pain symptoms, patients undergoing lumbar fusion at L4-L5 and L5-S1 for isthmic spondylolisthesis with predominant back pain symptoms may demonstrate improved long-term clinical outcomes for reported back pain, leg pain, and disability and reduced postoperative length of stay and narcotic consumption.

Expanding Access to Microneurosurgery in Low-Resource Settings: Feasibility of a Low-Cost Exoscope in Transforaminal Lumbar Interbody Fusion

Abstract Objectives Less than a quarter of the world population has access to microneurosurgical care within a range of 2 hours. We introduce a simplified exoscopic visualization system to achieve optical magnification, illumination, and video recording in low-resource settings. Materials and Methods We purchased a 48 megapixels industrial microscope camera with a heavy-duty support arm, a wide field c-mount lens, and an LED ring light at a total cost of US$ 125. Sixteen patients with lumbar degenerative disk disease were divided into an exoscope group and a conventional microscope group. In each group we performed four open and four minimally invasive transforaminal lumbar interbody fusion procedures. We further conducted a questionnaire-based assessment of the user experience. Results The overall user experience was positive. The exoscope achieved similar postoperative improvement with comparable blood loss and operating time as the conventional microscope. It provided a similar image quality, magnification and illumination. Yet, the lack of stereoscopic perception and the cumbersome adjustability of the camera position and angle resulted in a shallow learning curve. Most users strongly agreed that the exoscope would significantly improve surgical teaching. Over 75% reported they would recommend the exoscope to colleagues and all users saw its great potential for low-resource environments. Conclusion Our low-budget exoscope is technically non-inferior to the conventional binocular microscope and purchasable at a significantly lower price. It may thus help expand access to neurosurgical care and training worldwide.

MRI Assessment of the Early Disc Degeneration Two Levels above Fused Lumbar Spine Segment: A Comparison after Unilateral and Bilateral Transforaminal Lumbar Interbody Fusion (TLIF) Procedure.

Background: Adjacent segment degeneration (ASD) has become a great concern as a late complication in patients following fusion spine surgery with a potential need for revision surgery. Segments above the fused spine have higher mobility and they are especially prone to accelerated disc degeneration. The purpose of our study is to investigate early disc degenerative changes two levels above a surgically fused lumbar spine segment and to compare MRI analyses after unilateral and bilateral TLIF procedures. Methods: A total of 117 patients were included in this cross-sectional retrospective single center study (after bilateral TLIF surgery: n = 91, and after unilateral TLIF: n = 26). In both groups, the average patient age was similar: 62.84 years (SD = 12.53) in the unilateral TLIF group and 60.67 years (SD = 11.89) in the bilateral TLIF group. On average, MRI was performed 2.5 years after surgery (SD = 2.09). The modified eight-level Pfirrmann grading system was used for the assessment of disc degeneration severity. Descriptive statistics and the Mann–Whitney test were used to show differences in the Pfirrmann grades regarding the after-surgery period and the patient age. The Wilcoxon signed-rank test results were used to display differences in the Pfirrmann grades before and after surgery. Results: The comparison of mean values, regardless of the type of surgery, shows that this mean value is on average higher in the first segment adjacent to the fused spine segment. The assessment of the intervertebral disc structure in BIL TLIF is higher in both the first and the second segment. Early disc degeneration progression is subtle yet detectable (UNI TLIF 9.28% vs. BIL TLIF 16.74%). The assessment of the intervertebral disc structure is on average lower in patients aged less than 50 years at time of surgery compared with patients aged more than 50 years in UNI TLIF, and higher in the BIL TLIF group, for both the first and the second segment. Conclusion: Patients who had undergone unilateral TLIF fusion surgery have a lower rate of early disc degenerative changes. Considering a significantly higher rate of progressive disc degenerative changes in the elderly with bilateral fusion surgery, extra caution is required in the selection of appropriate surgical technique.

Adult Isthmic Spondylolisthesis: A Radiographic and Outcomes Analysis Comparing Circumferential Fusions Versus TLIF Procedures.

This was a retrospective cohort study. The objective of this study was to compare radiographic and patient-reported outcome measures (PROMs) between circumferential fusions and transforaminal lumbar interbody fusion (TLIF) for adult isthmic spondylolisthesis (IS). Definitive management of adult IS typically requires decompression and fusion. Multiple fusion techniques have been described, but literature is sparse in identifying the optimal technique. Patients with IS undergoing single-level or 2-level circumferential fusion or TLIF with a minimum 1-year follow-up were included. Patient demographics, surgical characteristics, and PROMs were extracted from patients' electronic medical records. Descriptive statistics and multivariate regression analysis compared outcomes with significance set at P -value &lt;0.05. A total of 78 circumferential fusions (48 open decompression and fusions and 30 circumferential fusions utilizing posterior percutaneous instrumentation) and 50 TLIF procedures were included. Length of stay was significantly longer when comparing circumferential procedures (3.56±0.96 d) versus TLIFs (2.88±1.14 d) ( P =0.002). The circumferential fusion group resulted in greater postoperative improvement in segmental lordosis [anterior/posterior (A/P): 6.45, TLIF: -1.99, P &lt;0.001], posterior disk height (A/P: 12.6 mm, TLIF: 8.9 mm, P &lt;0.001), and ∆disk height (A/P: 7.7 mm, TLIF: 3.6 mm, P &lt;0.001). Both groups significantly improved in all PROMs ( P &lt;0.001). While the circumferential fusion group had a significantly higher rate of perioperative surgical complications (12.82% vs. 2.00%, P =0.049), there was no difference in the rate of 30-day readmissions ( P =0.520) or revision surgeries between techniques ( P =0.057). Circumferential fusions are associated with improvements in radiographic outcomes compared with TLIFs, but this is at the expense of longer hospital length of stay and increased risk for perioperative complications. The surgical technique did not result in superior postoperative PROMs or differences in readmissions or revisions.

The use of intra-operative navigation during complex lumbar spine surgery under spinal anesthesia

BackgroundSpinal anesthesia is a safe and effective alternative to general anesthesia in both simple and complex lumbar surgery with numerous reported advantages leading to increased recent utilization. One potential barrier to the use of spinal anesthesia in lumbar surgery is the popularity of intraoperative computed tomography (CT) imaging. Intraoperative CT necessitates motionless patients and adds time to procedures, issues that may make surgeons hesitant to use concomitant spinal anesthesia. To date, the use of both techniques simultaneously has not been well described. ObjectiveWe propose that single-level lumbar fusions utilizing intraoperative CT scan acquisition and navigated instrumentation are feasible under single-dose spinal anesthesia without detrimental effect on image quality and navigation accuracy or need for spinal anesthetic re-dosing due to the additional time necessary. MethodsWe describe operative characteristics and intra-operative timing for our first five cases of transforaminal lumbar interbody fusion (TLIF) completed with intraoperative CT scan acquisition and navigated instrumentation performed under spinal anesthesia. ResultsThe five patients ranged in age from 59 to 79 years, with an average body mass index of 27.0 kg/m2. The average total operative time for each surgery 109.2 min, including approximately 6.3 min required for CT scan acquisition. There were no complications and post-operative imaging demonstrated no malpositioned pedicle screws. ConclusionSingle-level TLIF procedures utilizing intraoperative CT acquisition and navigated instrumentation can be feasibly completed under single-dose spinal anesthesia without need for intraoperative apneic periods and without deleterious effect on instrumentation accuracy.

Ten-Year Outcomes of Minimally Invasive Versus Open Transforaminal Lumbar Interbody Fusion in Patients With Single-Level Lumbar Spondylolisthesis.

A retrospective observational study. This study investigated the clinical and radiological results of minimally invasive (MI) versus open transforaminal lumbar interbody fusion (TLIF) in patients with single-level lumbar spondylolisthesis over a 10-year period. Few studies have compared 10-year follow-up outcomes between MI-TLIF and open TLIF. We retrospectively collected the outcome data of patients with single-level lumbar spondylolisthesis who underwent TLIF procedures using an MI (n = 108) or open (n = 53) approach. Fifty-two (48%) and 31 (58%) patients in the MI-TLIF and open TLIF groups, respectively, completed the 10-year follow-up. A primary clinical outcome included the Oswestry Disability Index (ODI) as well as visual analog scale (VAS) scores for back and leg pain at baseline and at 2, 5, and 10 years postoperatively. The radiographic fusion rate and incidence of secondary surgery due to adjacent segment disease were assessed at 2, 5, and 10 years postoperatively. Intraoperative blood loss and length of hospitalization were significantly lower in the MI-TLIF group than in the open TLIF group. At 2 years postoperatively, the ODI and VAS scores for back and leg pain were significantly lower in the MI-TLIF group than in the open TLIF group. No significant differences were found in VAS scores for back and leg pain or ODI scores between the two groups at 10 years postoperatively. Radiographic fusion rates and prevalence of secondary surgery for adjacent segment disease were not significantly different between the groups at 10 years postoperatively. Efficacy of MI-TLIF for patients with single-level lumbar spondylolisthesis is comparable to that of open TLIF over 10-years. However, MI-TLIF may have superior perioperative recovery and 2-year postoperative functional outcomes than open TLIF.Level of Evidence: 3.

Contribution of Multilevel Transformainal Lumbar Interbody Fusion Surgery to Restoration of Lumbar Lordosis in Patients with Degenerative Spine: Comparison of Long and Short Level Fusion.

To investigate the effect of multilevel transforaminal lumbar interbody fusion (TLIF) procedures in lumbar degenerative spine conditions on the restoration of lumbar lordosis (LL) in patients with short- and long-level fusion, and to examine the associated radiological results. This retrospective study reviewed patients with degenerative spinal diseases who underwent lumbar fusion using a multilevel TLIF procedure. Patients with three or fewer segments involved in fusion were assigned to the shortlevel fusion group and those with more than three segments involved in fusion were assigned to the long-level fusion group. The anteroposterior and lateral spine radiographs of the patients were used to measure LL, distal lumbar lordosis and radiological parameters. The study included 47 patients who met the inclusion criteria, with a mean age of 60.4 ± 12.2 years. The mean follow-up time of our patients was 18.3 ± 11 months. Thirty-five (74.5%) patients were women and 12 (25.5%) were men. Overall, 12 patients underwent 3-level and 35 patients underwent 2-level TLIF. Long-level fusion was performed in 24 patients and short-level fusion was performed in 23 patients. Multilevel TLIF can be used to correct spinopelvic alignment when applied with the appropriate indications and techniques in patients with degenerative spinal disorders. Multilevel TLIF is associated with substantial improvements in LL, distal lumbar lordosis, and SVA (sagittal vertical axis). It also helps to correct the correlation between PI and LL.

Single-level TLIF Versus LLIF at L4-5: A Comparison of Patient-reported Outcomes and Recovery Ratios.

Both transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) are suitable for achievement of lumbar arthrodesis. Comparative studies have observed complications and outcomes without stratification by lumbar level. This study aims to assess patient-reported outcome measures (PROMs) and recovery in TLIF and LLIF at L4-5. Patients undergoing primary, elective, single-level, TLIF or LLIF procedures at L4-5 were grouped. Demographics, perioperative characteristics, and postoperative complication rates were collected. PROMs included Patient-Reported Outcome Measurement Information System Physical Function, visual analog scale (VAS) back and leg, Oswestry Disability Index, and 12-Item Short-Form Physical Component Summary, and Mental Component Summary and were collected at preoperative, 6-week, 12-week, 6-month, 1-year, and 2-year time points. Delta values and recovery ratios (RRs) were calculated for all PROMs at all time points. Demographics, perioperative characteristics, and postoperative complications were compared using chi-squared and Student t-test for categorical and continuous variables, respectively. Differences in mean PROMs, delta values, and RR at each time point were evaluated using unpaired Student's t-test. Three hundred sixty TLIF and 46 LLIF patients were included. Most (54.3%) were men, mean age 56.3 years, and mean body mass index 30.8 kg/m2. Body mass index and insurance significantly differed (P ≤ 0.045, all). TLIF showed significantly greater mean operative time, length of stay, and postoperative narcotic consumption (P < 0.033, all) and greater postoperative nausea/vomiting (P = 0.004). No preoperative PROMs significantly differed. TLIF cohort had significantly greater VAS back at 6 months and VAS leg at 12 weeks and 6 months (P < 0.034, all). No mean delta PROMs or RRs significantly differed. LLIF demonstrated significantly reduced length of stay, postoperative narcotic consumption, and postoperative nausea/vomiting and significantly improved VAS back at 6 months and VAS leg at 12 weeks and 6 months versus TLIF. Although 2-year PROMs and RRs did not significantly differ, our findings may suggest improved midterm follow-up pain scores for LLIF patients.

How Do Patient-Reported Outcomes Vary Between Lumbar Fusion Patients with Complete Versus Incomplete Follow-Up?

We sought to assess differences in patient-reported outcome measures (PROMs) between patients who do and do not follow up for 2 years after lumbar fusion. Primary, elective, single-level anterior lumbar interbody fusion, lateral lumbar interbody fusion, or transforaminal lumbar interbody fusion procedures were identified. Patients were grouped by 2-year PROM follow-up completion. Mean and delta PROM scores for visual analog scale (VAS) back and leg, Oswestry Disability Index (ODI), short-form (SF)-12 Physical Composite Score (PCS), and Mental Composite Score (MCS) were computed for both groups preoperatively and postoperatively. Minimum clinically important difference (MCID) achievement was determined for PROM scores using established threshold values. Linear and logistic regression assessed mean and ΔPROM scores as predictors of 2-year follow-up completion and compared MCID achievement between groups, respectively. We included 316 lumbar fusion patients. PROM scores were more favorable for complete follow-up patients for 6-month VAS back (P= 0.003), 6-month and 1-year ODI (P ≤ 0.027, both), and 6-week and 6-month SF-12 PCS (P ≤ 0.015, both). Six-month VAS back (P= 0.007); 6-month and 1-year ODI (P ≤ 0.028, both); 6-week, 6-month, and 1-year SF-12 PCS (P ≤ 0.041, all); and 6-week SF-12 MCS (P ≤ 0.028, both) significantly predicted 2-year follow-up. ΔPROMs significantly differed between groups at 1 year for ΔVAS leg (P= 0.029), ΔODI (P= 0.013), and ΔSF-12 MCS (P= 0.004). One-year ΔVAS leg (P= 0.035), ΔODI (P= 0.011), and ΔSF-12 MCS (P= 0.003) significantly predicted follow-up. MCID achievement for ΔPROMs significantly differed between groups for 6-week VAS leg (P= 0.035), overall ODI (P= 0.034), and SF-12 PCS from 12 weeks through 1 year (P ≤ 0.011, all) and overall (P < 0.001). Patients with full follow-up demonstrated significantly more favorable outcome scores and improvement in pain, disability, and physical function at several postoperative time points.

Comparison of Percutaneous Transforaminal Endoscopic Decompression and Transforaminal Lumbar Interbody Fusion in the Treatment of Single-Level Lumbar Disc Herniation with Modic Type I Changes.

BackgroundModic changes (MC) are generally considered to be related to degenerative disc disease, and there is no uniform standard for surgical methods for lumbar disc herniation (LDH) accompanied by Modic type I changes (MC I). The purpose of this study was to observe the clinical results of percutaneous transforaminal endoscopic decompression (PTED) and transforaminal lumbar interbody fusion (TLIF) for treatment of LDH accompanied by MC I.MethodsOf the 53 consecutive patients included, 29 underwent PTED and 24 underwent TLIF. All patients were followed up for at least 24 months. Preoperative demographic characteristics, perioperative outcomes, and clinical outcomes were recorded. Visual analog scale (VAS) scores, Oswestry disability index (ODI) scores, and modified Macnab criteria were used to assess clinical results.ResultsThe mean age was 53.7±9.2 years in the PTED group and 53.6±9.6 years in the TLIF group. The scores of VAS legs, VAS back and ODI in the two groups after operation were significantly improved compared with those before operation (P<0.05). Notably, the VAS back pain score and ODI in the PTED group showed an increasing trend with time. And the VAS back pain scores and ODI of the two groups were statistically different at 1 year and 2 years postoperatively (P<0.05). In addition, compared with the TLIF group, the PTED group showed less operation time, blood loss, and postoperative hospital stay (P<0.05). At the final follow-up, the excellent rates were 91.7% and 86.2% in the fusion and PTED groups, respectively.ConclusionBoth PTED and TLIF procedures significantly improved the clinical symptoms of single-level LDH patients with MC I. Compared with TLIF, MC I may affect the improvement of low back pain and functional status after PTED.

The Effect of Oblique Lumbar Interbody Fusion Compared with Transforaminal Lumbar Interbody Fusion Combined with Enhanced Recovery after Surgery Program on Patients with Lumbar Degenerative Disease at Short-Term Follow-Up.

Purpose Oblique lumbar interbody fusion (OLIF) approach has been increasingly frequently performed in recent years. However, neither studies of OLIF approach nor the researches of the application of enhanced recovery after surgery (ERAS) in spinal surgery are relatively rare. Here, our study is aimed at investigating the therapeutic effects of the application of OLIF compared with transforaminal lumbar interbody fusion (TLIF) approach combined with ERAS in dealing with this disorder at short-term follow-up. Material and Methods. Thirty-eight patients who undergone OLIF and forty patients who undergone TLIF with pedicle screws were included in our study. The concept of ERAS was applied in the perioperative period of the patients. Preoperative and postoperative laboratory test indexes of blood were examined and evaluated in all individuals. Visual analogue scale (VAS), Oswestry disability index (ODI), and Clinical Symptom Score of the Japanese Orthopaedic Association (JOA) were used in preoperative evaluation and postoperative follow-up. Satisfaction survey was also performed after surgery. Result The postoperative results of red blood count, C-reaction protein, D-dimer, and albumin were still within the reference ranges in most of the patients. It was shown that objective evaluations including VAS score, ODI index, and JOA score were significantly improved after OLIF and TLIF surgery. The follow-up of 6 months after surgery showed that VAS, ODI, and JOA were improved more in the OLIF group than that in the TLIF group. The overall satisfaction (satisfied and very satisfied) was 95% and 97.4% in the TLIF group and the OLIF group, respectively, and there was no difference between the two groups. Conclusion This study indicated that OLIF and TLIF approach were both rather effective therapies for patients with lumbar degenerative diseases. The effect of OLIF procedure could be better than TLIF procedure in the early stage after surgery.

Comparing hyperlordotic and standard lordotic cages for achieving segmental lumbar lordosis during transforaminal lumbar interbody fusion in adult spinal deformity surgery.

Few studies directly compare the effect of interbody cages with different degrees of lordosis in producing segmental lumbar lordosis (SLL) in the transforaminal lumbar interbody fusion (TLIF) procedure. Thus, we aimed to investigate changes in SLL in hyperlordotic cages compared to standard lordotic cages in open TLIF procedures. Thirty-eight consecutive patients who received open TLIF procedures performed by a single surgeon between 2017 and 2018 were reviewed. Twenty patients had "hyperlordotic cages" (20° lordosis), while 18 patients had "standard lordotic cages" (6° lordosis). Twenty-three patients had one-level TLIF procedures and 15 had two-level TLIF. Standard radiographic measurements, including SLL were assessed preoperatively, postoperatively, and at 1-year follow-up. SLL was measured from the superior endplate of the cephalad vertebra to the inferior endplate of the caudal vertebra. Changes in SLL were compared using Student's and paired t-tests. In one- and two-level open TLIF, both hyperlordotic and standard lordotic cages produced significant improvement in SLL. Among those receiving a one-level TLIF, SLL increased 7.8° (P=0.024) in those with standard lordotic cages; it increased 8.2° (P=0.020) in those with hyperlordotic cages. Among those receiving a two-level TLIF, SLL increased 13.9° (P=0.032) in those with standard lordotic cages; it increased 8.8° (P=0.023) in those with hyperlordotic cages. However, the improvement in SLL was not significantly different between the two cage types in either one or two-level TLIF procedures (P=0.917, P=0.389). At 1-year follow-up, there was no significant change in SLL, among standard lordotic and hyperlordotic cages (P=0.501, P=0.781). Although it is theorized that hyperlordotic cages would increase SLL during open TLIF procedures more than standard lordotic cages, our data failed to demonstrate that. As our study examined cases performed by a single surgeon immediately before and after adoption of these lordotic cages, it is likely that surgical technique is of equal or greater importance in improving SLL than the amount of lordosis designed into interbody cages.

240. Utility of intraoperative neuromonitoring alerts relating to adverse outcomes in spine surgery: a study of 289 patients

<h3>BACKGROUND CONTEXT</h3> Although rare, one of the most problematic complications during spine surgery is neurologic injury with subsequent deficit. The use of multimodal intraoperative neuromonitoring (MIOM) during spine surgery provides the surgical team with real-time assessment of the neurological physiology and function. MIOM is thought to be sensitive and specific for identifying perioperative neurological injury in spinal surgery especially deformity surgery. However, results from recent studies have cast doubt on the effectiveness of certain MIOM techniques in detecting neurological injury in spine surgery patients. <h3>PURPOSE</h3> The purpose of this study was to improve spine surgery patient safety and outcomes by minimizing the incidence of postoperative new neurological deficits correlated to intraoperative neuromonitoring alerts from two neuromonitoring signals: motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs). <h3>STUDY DESIGN/SETTING</h3> A multicenter, multisurgeon prospective quality improvement initiative that was performed in conjunction with neuro alert (NA) monitoring services. All data was retrospectively analyzed. <h3>PATIENT SAMPLE</h3> A total of 289 patients who (1) received nondeformity lumbar (45%), cervical (45%) or thoracic (10%) surgery between July 2018 and July 2019 and (2) underwent SSEP and MEP monitoring throughout the entire surgery. <h3>OUTCOME MEASURES</h3> This study investigated the incidence of immediate postoperative (≤ 48 hours) new neurological deficits. sensitivty, specificity, postive predictive value (PPV), and negative predictive value (NPV) was calculated for the SSEP and MEP signals. <h3>METHODS</h3> This study was a multicenter, multisurgeon prospective quality improvement initiative that was performed in conjunction with neuro alert (NA) monitoring services. All neuromonitoring was carried out in accordance with the guidelines set forth by the American Academy of Neurology and the American Board for Neurophysiological Monitoring Programs. Two commonly used MIOM signals were tracked: somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs). Intraoperative data were recorded using a paper data collection tool. SSEP and MEP signal changes were classified as alerts based on the following best practices guidelines outlined in the literature: 50% or greater decrease in signal amplitude and/or a 10% or greater increase in signal latency with no signal recovery. Immediate postoperative (≤ 48 hours) new neurological deficit status was assessed for all patients. Neurological deficit information was recorded via paper during a postoperative physical exam that all physicians conducted on the patient within 48 hours after surgery. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the SSEP and MEP signals were calculated. <h3>RESULTS</h3> SSEP and MEP neuromonitoring data was analyzed for 289 patients who (1) received non-deformity lumbar (45%), cervical (45%) or thoracic (10%) surgery between July 2018 and July 2019 and (2) underwent SSEP and MEP monitoring throughout the entire surgery. A total of 22 MEP and 16 SSEP alerts were triggered. Ninety percent (20) of MEP alerts occurred during anterior cervical discectomy and fusion (ACDF) procedures; one MEP alert was triggered during a posterior cervical fusion and one MEP alert was triggered during a lumbar laminectomy. 56% (9) of SSEP alerts occurred during transforaminal lumbar interbody fusion procedures while 25% (4) occurred during ACDFs and 19% (3) occurred during lumbar laminectomy surgeries. MEP and SSEP alerts were most frequently triggered during the decompression surgical step (45% and 25%, respectively). There were 6 instances (n = 6) of new neurological deficits that occurred within 48 hours postsurgery. These deficits were as follows: foot drop (n = 1), leg weakness (n = 1), arm weakness (n = 2), bilateral paraparesis (n = 1) and unilateral paraparesis (n = 1). The patient who developed unilateral paraparesis was myelopathic. All other patients with new neurological deficits did not have a history of myelopathy. The MEP alert should have been triggered for all 6 patients, however the signal was only alerted in the patient who developed bilateral paraparesis and in one patient who developed arm weakness. In 4/6 patients, MEP alerts were not triggered but a new neurological deficit occurred, resulting in a false negative rate of 67% and a sensitivity of 33%. In addition, MEPs had a specificity of 92.4%, PPV of 11% and NPV of 98.5%. The SSEP signal showed 100% sensitivity and displayed a specificity, PPV and NPV of 95.2%, 12.5% and 100%, respectively. <h3>CONCLUSIONS</h3> The MEP signal had a low sensitivity of 33%, which differed greatly from that of the SSEP signal (100%). The specificity, PPV and NPV were comparable between the SSEPs and MEPs. The PPV was low for both signals. Results indicate that the accuracy of SSEP and MEP alerts in detecting new neurological deficits in spine surgery patients immediately postsurgery is questionable. The effectiveness of these two intraoperative neuromonitoring techniques in identifying neurological injury seems uncertain and needs to be explored further. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs

Charlson Comorbidity Index: An Inaccurate Predictor of Minimally Invasive Lumbar Spinal Fusion Outcomes.

There is a scarcity of research on the Charlson Comorbidity Index (CCI) and its influence on minimum clinically important difference (MCID) achievement after minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF). The objective of this study is to detail the association between the CCI and attaining MCID after MIS TLIF. A prospective surgical registry was retrospectively reviewed for spine surgeries between May 2015 and February 2019. Inclusion criteria were primary or revision, 1- or 2-level MIS TLIF procedures. Patients were stratified based on CCI score: 0 points (no comorbidities), 1-2 points (mild CCI), ≥3 points (moderate CCI). Preoperative, intraoperative, and postoperative variables were assessed by subgroup using appropriate statistical analysis. Subgroups were analyzed with linear regression or χ2 tests for continuous or categorical variables, respectively. Subgroup scores, improvement, and MCID achievement were assessed at postoperative timepoints (eg, 6 weeks, 12 weeks, 6 months, and 1 year) for back and leg pain, Oswestry Disability Index (ODI), SF-12 Physical Composite Score (PCS), and Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS PF). A total of 171 patients were included (n = 51 [no comorbidities], n = 73 [mild CCI], and n = 47 [moderate CCI]). Higher CCI patients were older and more likely to be smokers, diabetic, arthritic, hypertensive, or have a malignancy history (P < 0.003). Preoperatively, ODI and PROMIS PF were the only patient-reported outcomes with a significant association by CCI group (P = 0.015 and 0.014). Back pain was the only measure that had a significant association with the CCI subgroup at 1 year for score (P = 0.002) or MCID (P = 0.028). By 1 year, regardless of the number of comorbidities, a similar proportion of patients undergoing MIS TLIF were able to achieve MCID for visual analog scale leg, SF-12 PCS, and PROMIS PF. Patients with higher comorbidities are not likely to experience a significant difference in symptom improvement. Regardless of CCI score, MIS TLIF can have a significant benefit for patients. 4. Text.

Iatrogenic muscle damage in transforaminal lumbar interbody fusion and adjacent segment degeneration: a comparative finite element analysis of open and minimally invasive surgeries.

Lumbar procedures for Transforaminal Lumbar Interbody Fusion (TLIF) range from open (OS) to minimally invasive surgeries (MIS) to preserve paraspinal musculature. We quantify the biomechanics of cross-sectional area (CSA) reduction of paraspinal muscles following TLIF on the adjacent segments. ROM was acquired from a thoracolumbar ribcage finite element (FE) model across each FSU for flexion-extension. A L4-L5 TLIF model was created. The ROM in the TLIF model was used to predict muscle forces via OpenSim. Muscle fiber CSA at L4 and L5 were reduced from 4.8%, 20.7%, and 90% to simulate muscle damage. The predicted muscle forces and ROM were applied to the TLIF model for flexion-extension. Stresses were recorded for each model. Increased ROM was present at the cephalad (L3-L4) and L2-L3 level in the TLIF model compared to the intact model. Graded changes in paraspinal muscles were seen, the largest being in the quadratus lumborum and multifidus. Likewise, intradiscal pressures and annulus stresses at the cephalad level increased with increasing CSA reduction. CSA reduction during the TLIF procedure can lead to adjacent segment alterations in the spinal element stresses and potential for continued back pain, postoperatively. Therefore, minimally invasive techniques may benefit the patient.

Preliminary Results of Expandable Transforaminal Lumbar Interbody Fusion Cages

Background: Compared with static cages, expandable cages for Transforaminal Lumbar Interbody Fusion (TLIF), are thought to require less posterior bony removal and nerve root retraction. They may allow the creation of a greater lordotic angle and lordosis restoration. Objective: This study investigated whether TLIF using an expandable lordotic interbody cage facilitates an improvement in both segmental lordosis and the restoration of intradiscal height. Methods: A total of 32 patients with 40 operated segments underwent TLIF surgery for lumbar degenerative disc disease and were consecutively included in this prospective observational study. Of those patients, 25 received monosegmental treatment, six were treated bisegmentally, and one was treated trisegmentally. All patients were assessed clinically and radiographically preoperatively, as well as one week, six months, and two years postoperatively. Results: Two patients required revision for screw loosening and pseudarthrosis. In four patients, the endplate was violated intraoperatively due to cage placement. Postoperatively, cage subsidence was observed in four patients. Significant improvement in the mean degree of spondylolisthesis was noted at the two-year mark. Mean segmental lordosis improved postoperatively. A significant increase in mean disc height of the treated segment was also found. Overall, with the exception of pain, no significant clinical or radiographic changes were reported between the first postoperative week and the two-year year follow-up mark. The mean pain, functional, and quality of life outcomes improved significantly from the preoperative to postoperative period, with no deterioration between six months and two years. Conclusion: This study demonstrates that favorable outcomes can be achieved by using an expandable titanium cage in TLIF procedures.

English

BACKGROUND Operative treatment and fusion for isthmic spondylolisthesis can be achieved by various fusion techniques such as posterolateral fusion (PLF), anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF) and circumferential fusion. The purpose of this study is to evaluate the clinical outcome and radiological correction achieved after TLIF and assess the correlation between them if any. METHODS This is a retrospective cohort study analysing 30 cases of adult isthmic spondylolisthesis who failed conservative treatment and were then treated with transforaminal lumbar interbody fusion between 2011 and 2013. The clinical follow-up was done with the modified Oswestry disability index (ODI) and visual pain analogue score (VPAS). For the radiological follow-up radiographs were taken and several radiographic parameters were noted and analysed. RESULTS The mean of the Oswestry disability index scores in all patients decreased from 67.73 to 13.1 at final follow up. Similarly, visual pain analogue score reduced from mean 8.43 to 1.76 at final follow up. The average anterolisthesis was significantly reduced from the preoperative 27.1 ± 14 % to 7.1 ± 5 % at final follow-up radiographs (P &lt; 0.001). Segmental lordosis increased from a mean of 11.5 degrees to 15.7 degrees. The difference in slip angle was significant from preoperative -4.87 ± 4.8 degrees and - 7.23 ± 4.63 degrees on the initial postoperative and - 7.2 ± 4.57 degrees at final follow-up radiographs (P = 0.14 and 0.13 respectively). CONCLUSIONS Thus, adult isthmic spondylolisthesis can be safely and effectively treated by TLIF with significant clinical relief and decrease in disability. TLIF procedure in isthmic spondylolisthesis is capable of reducing the sagittal translation and restoring disc height. Also, sagittal alignment and lordosis can be restored to a large extent. KEYWORDS Spondylolisthesis, Pelvic Incidence, Sagittal Balance, TLIF