Restoration Of Segmental Lordosis Research Articles

Analysis of Spinopelvic Sagittal Balance and Persistent Low Back Pain (PLBP) for Degenerative Spondylolisthesis (DS) following Posterior Lumbar Interbody Fusion (PLIF)

Objective To investigate the change of spinopelvic sagittal balance and clinical outcomes after posterior lumbar interbody fusion (PLIF) in patients with degenerative spondylolisthesis (DS), especially the relationship between sagittal spinopelvic parameters and persistent low back pain (PLBP). Methods 107 patients who were diagnosed with DS and underwent PLIF in our department were enrolled retrospectively in the present study. Sagittal spinopelvic parameters including lumbar lordosis (LL), segmental lordosis (SL), height of the disc (HOD), sacral slope (SS), pelvic incidence (PI), and pelvic tilt (PT) were recorded pre- and postoperatively. Sagittal balance and clinical outcomes were compared between patients with and without PLBP. Pearson correlation was used to analyze the change of sagittal balance parameters and clinical functions. Logistic regression analysis was performed to examine the risk factors of PLBP. Results It showed significant improvements of SL, HOD, and PT postoperatively. Both the Numeric Rating Scale (NRS) and Oswestry Disability Index (ODI) had significant improvement postoperatively. Change of PT and SL also differed observably between patients with and without PLBP. SL and PT were correlated with NRS and ODI, and insufficient restoration of PT was an independent factor for PLBP. Conclusion The sagittal balance parameters and clinical outcomes can be improved markedly via PLIF for treating DS. Restoration of SL and PT was correlated with satisfactory outcomes, and adequate improvement of PT may have positive impact on reducing PLBP.

Minimally invasive oblique interbody fusion for correction of iatrogenic lumbar deformity.

Spinal instability may arise as a consequence of decompressive lumbar surgery. An oblique lumbar interbody fusion combined with pedicle screw fixation can provide indirect decompression on neural elements, stabilization of mobile spondylolisthesis, and restoration of segmental lordosis. Minimally invasive techniques may facilitate a shorter hospitalization and faster recovery than a traditional open revision operation. The authors describe the use of an anterior interbody fusion via an oblique retroperitoneal approach and posterior pedicle screw fixation to treat a 67-year-old woman who developed L3–4 and L4–5 unstable spondylolisthesis after a lumbar laminectomy.The video can be found here: https://youtu.be/KWwGMIoDrmU.

Comparison of long-term effect between minimally invasive and open approaches in one-level posterior lumbar interbody fusion: a 10-12 year prospective study

Objective To compare the long-term effect between minimally invasive (MIS) and open approaches in one-level posterior lumbar interbody fusion (O-PLIF) after more than 10 years follow up. Methods All 131 patients (lumbar spine lesions) in our hospital were randomized into MIS-PLIF group and O-PLIF group from March 2006 to March 2008. In MIS-PLIF group, there are 66 patients, 34 males and 32 females, with the average of 52.3±6.7 years old (range from 40 to 63). In O-PLIF group, there are 65 patients, 29 males and 36 females, with the average of 51.1±6.9 years old (range from 46 to 63). Regarding March 2018 as last follow-up, differences in intervertebral disc height and segmental lordosis restoration of the operation segment, lumbar lordosis restoration, multifidus cross section area (CSA), multifidus atrophy rate, fusion rate, visual analogue scale(VAS) for back and leg pain, Oswestry Disability Index(ODI), Japanese Orthopaedic Association cores (JOA) and postoperative long-term complications were evaluated between the two groups. The related risk factors of postoperative long-term complications were evaluated in further analysis. Results Complete follow-up data were available on 37 patients in MIS-PLIF group and 35 patients in O-PLIF group, with the follow-up rate of 56.1% and 53.8% respectively, and with the mean follow-up time of 134.5 ±8.4 and 137.1±5.8 months respectively. At three time nodes of one year after operation, five years after operation and last follow-up after operation, there were significant differences in lumbar lordosis restoration (one year after operation and last follow-up after operation)(5.0°±2.3° vs. 3.9°±1.4°; 4.7°±2.4° vs. 3.7°±1.5°), multifidus CSA (965.4±164.9 mm2vs. 884.9±168.2 mm2; 891.1±155.9 mm2vs. 783.2±163.0 mm2; 764.8±148.3 mm2 vs. 643.5±150.0 mm2), multifidus atrophy rate (8.5%±2.5% vs. 16.6%±5.8%; 15.6%±3.5% vs. 26.2%±7.4%; 27.6%±6.5% vs. 39.3%±9.3%), postoperative VAS for back pain (2.2±1.0 vs. 2.9±1.2; 1.7±0.9 vs. 2.2±1.0; 1.4±1.0 vs. 2.2±1.2), JOA score (22.3±3.8 vs. 19.9±4.2; 23.1±4.3 vs. 19.3±3.9; 22.4±4.2 vs. 19.6±4.0) and ODI (11.6%±4.8% vs. 22.0%±7.7%; 9.4%±3.9% vs. 12.3%±4.9%; 8.6%±4.0% vs. 11.0%±4.6%) between the two groups (P 0.05). Intractable back pain and adjacent segment disease were the major postoperative long-term complications for MIS-PLIF group (3 cases and 2 cases) and O-PLIF group (10 cases and 7 cases), and the difference was statistically significant in the intractable back pain incidence rate (8.5% vs. 28.6%, χ2=5.090, P=0.024), but not in the adjacent segment disease(5.4% vs. 20%, χ2=0.002, P=0.061). What's more, patients with intractable back pain suffered more obviously multifidus atrophy than patients without intractable back pain at three time nodes of one year after operation (19.4±4.4% vs. 10.9±5.1%, P<0.05), five years after operation (30.2±5.4% vs. 18.7±6.7%, P<0.05) and last follow-up after operation (44.5±5.7% vs. 30.8±8.9%, P<0.05). Conclusion In the long-term follow up, compared with O-PLIF, MIS-PLIF had advantages in better maintenance of lumbar lordosis, protection of the multifidus muscle, reduced lower back pain, JOA score, ODI score and intractable back pain incidence rate. Multifidus atrophy may be a related risk factor of intractable back pain. Key words: Lumbar vertebrae; Surgical procedures, minimally invasive; Spinal fusion

Adequate Restoration of Disc Height and Segmental Lordosis by Lumbar Interbody Fusion Decreases Adjacent Segment Degeneration

This study aimed to investigate the effects of lumbar interbody fusion-induced biomechanical changes on the adjacent segments, especially disc height and segmental lordosis restoration, and to provide more information for proper surgical strategy selection. The medical records of 528 patients who underwent posterior lumbar interbody fusion were retrospectively reviewed, and a total of 89 patients were included. Surgical indications included degenerative spondylolisthesis (nonspondylolytic), marked disc herniation, or lumbar spinal stenosis requiring extensive decompression at L4/5. Postoperative adjacent segment degeneration (ASD) was assessed based on X-rays and functional status. Disc height, foraminal height, segmental lordosis, lumbar lordosis, and cage geometry were compared between the ASD and non-ASD patients. To identify the possible risk factors for radiographic ASD, univariate analysis was performed first, followed by multivariate logistic regression using variables with P < 0.20. Univariate analysis revealed that the postoperative disc height in the non-ASD group were significantly greater than in the ASD group. The postoperative segmental lordosis in the non-ASD group was significantly greater than that in the ASD group, and the lumbar lordosis in the non-ASD group was also significantly greater than that in the ASD group at the final follow-up visit. Four variables were identified as independent risk factors for ASD by subsequent multivariate logistic regression: postoperative relative disc height of L4/5 (P= 0.011), postoperative segmental lordosis (P= 0.046), lumbar lordosis at the final follow-up visit (P=0.007), and cage height (P= 0.038). Improved lumbar lordosis is correlated with a lower incidence of ASD, and adequate disc height and segmental lordosis restoration are essential for ASD prevention.

Circumferential fusion: a comparative analysis between anterior lumbar interbody fusion with posterior pedicle screw fixation and transforaminal lumbar interbody fusion for L5–S1 isthmic spondylolisthesis

Background ContextTransforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion with percutaneous pedicle screws (ALIFPS) offer significantly higher radiographic fusion rates than other fusion techniques for L5–S1 isthmic spondylolisthesis (IS). As it stands, there is a relative paucity of comparative data of the two techniques. PurposeTo define the clinical, radiographic, and financial differences between TLIF and ALIFPS for L5–S1 IS. Design/SettingA retrospective cohort study conducted at a single tertiary care center. Patient SampleSixty-six patients who underwent either TLIF or ALIPFS for L5–S1 IS at a single tertiary care center between 2009 and 2014. Outcome MeasuresQuality of life outcome scores including the EuroQol-5 Dimensions (EQ-5D), Pain Disability Questionnaire (PDQ), and Patient Health Questionnaire-9 (PHQ-9). Sagittal balance parameters including: pelvic incidence, pelvic tilt, sacral slope, segmental lordosis, total lordosis, degree of slip, disc height, and L1-axis S1 distance (LASD). Cost measures included in-hospital charges, hospital length of stay (LOS), and post-admission costs accrued over 1 year. MethodsQuality of life (QoL) outcome scores, radiographic data, and financial data were collected with a minimum of 1-year follow-up. Clinical results were investigated using the PDQ, PHQ-9, and EQ-5D. Radiographic measurements included lumbar lordosis, segmental lordosis, pelvic tilt, pelvic incidence, height of disc, L-1 axis S-1 distance, and the degree of slip. Cost data were generated based on patient-level resource utilization. Comparative data were presented as median with interquartile range (IQR). Continuous variables were compared using either independent Student t tests assuming unequal variance or Mann-Whitney U tests for parametric and nonparametric variables, respectively. The minimally clinical important difference (MCID) used for each questionnaire was as follows: PDQ (26), PHQ-9 (5), and EQ-5D (0.4). ResultsA total of 66 patients met inclusion criteria. In the ALIFPS cohort, PDQ scores improved from 69 [47, 82] to 26 [18.2, 79.7], p=.02. In the TLIF cohort, PDQ scores improved from 73 [46, 85] to 48.5 [23, 67.5], p=.01. Both groups also showed a significant improvement in EQ-5D scores at 1 year, but the ALIFPS group showed a significantly greater improvement in EQ-5D scores at 1 year (0.1 [0,0.2] vs. 0.2 [0.1, 0.4], p=.02). Furthermore, only the ALIFPS cohort showed a significant improvement in segmental lordosis. The ALIFPS cohort showed a significantly greater improvement in disc height than did TLIF (3.5 [2, 5.5] vs. 6.7 [4.1, 10], p=.01). No significant differences were found in the direct costs of both procedures. ConclusionsOur findings suggest that anterior lumbar interbody fusion with percutaneous pedicle screws can achieve better clinical outcomes compared with TLIF for the treatment of IS. We believe the superior radiographic outcomes achieved through ALIFPS, namely a greater restoration of segmental lordosis and disc height, may have contributed to the improved clinical outcomes presented in the current study.

Comparison of Outcomes of Anterior, Posterior, and Transforaminal Lumbar Interbody Fusion Surgery at a Single Lumbar Level with Degenerative Spinal Disease

The fusion rate in spinal surgery may vary in relation to the technique, and it remains unknown which surgical technique provides the best fusion rate and surgical outcome. We aimed to compare radiologic and surgical results between 3 surgical techniques used for lumbar interbody fusion. Participants included 77 patients diagnosed with degenerative spinal stenosis including spondylolytic spondylolisthesis. Patients were divided into 3 groups according to surgical technique: anterior lumbar interbody fusion (ALIF, n= 26), transforaminal lumbar interbody fusion (TLIF, n= 21), and posterior lumbar interbody fusion (PLIF, n= 30). Various radiologic parameters were measured, including fusion rates. Significant changes after surgery were observed in the ALIF group for the percentage of vertebral body slippage, anterior disk height, posterior disk height, and segmental range of movement (ROM). The fusion rate on computed tomography (CT) scan at the final follow-up was 69.2% in the ALIF group, 72.7% in the TLIF group, and 64.3% in the PLIF group. The cage subsidence rate 2 years after surgery was 15.4% in the ALIF group, 38.1% in the TLIF group, and 10% in the PLIF group. ALIF was associated with better restoration of segmental lordosis. The fusion rate on CT scan and with segmental ROM did not differ between the 3 groups. TLIF was associated with a better postoperative visual analog scale. PLIF showed the lowest cage subsidence rate. Therefore, it is difficult to know which surgical technique is better among the 3 groups because each surgical method has its own advantages.

Evaluation of the location of intervertebral cages during oblique lateral interbody fusion surgery to achieve sagittal correction.

Introduction Oblique lateral interbody fusion (OLIF) can achieve recovery of lumbar lordosis (LL) in minimally invasive manner. The current study aimed to evaluate the location of lateral intervertebral cages during OLIF in terms of LL correction. Methods The subjects were patients who underwent OLIF for lumbar degenerative diseases, including lumbar spinal stenosis, spondylolisthesis, and discogenic low back pain. Their clinical outcome was evaluated using visual analogue scale on lower back pain (LBP), leg pain and numbness. The following parameters were retrospectively evaluated on plain radiographic images and computed tomography scans before and at 1 year after OLIF: the intervertebral height, vertebral translation, and sagittal angle. The cage position was defined by equally dividing the caudal endplate into five zones (I to V), and its association with segmental lordosis restoration was analyzed. Subjects were also evaluated for a postoperative endplate injury. Results Eighty patients (121 fused levels) with lumbar degeneration who underwent OLIF were included. There were no significant specific distribution in preoperative disc pathology such as disc angle, height, and translation. After OLIF, sagittal alignment was improved with an average correction angle of 3.8º at the instrumented segments in a level-independent fashion. All cases showed significant improvement in clinical outcomes, and had improvement in the radiological parameters (P<0.05). A detailed analysis of the cage position showed that the most significant sagittal correction and the most postoperative endplate injuries occurred in the farthest anterior zone (I). Cages with a 12-mm height were associated with more endplate injuries compared with shorter cages (8 or 10 mm). Conclusions OLIF improves sagittal alignment with an average correction angle of 3.8º at the instrumented segments. We suggest that the optimal cage position for better lordosis correction and the fewest endplate injuries is zone II with a cage height of up to 10 mm.

Effects of intradiscal vacuum phenomenon on surgical outcome of lateral interbody fusion for degenerative lumbar disease.

OBJECTIVE The authors investigated whether the presence of intradiscal vacuum phenomenon (IVP) results in greater correction of disc height and restoration of segmental lordosis (SL). METHODS A retrospective chart review was performed on every patient at the University of South Florida's Department of Neurosurgery treated with lateral lumbar interbody fusion between 2011 and 2015. From these charts, preoperative plain radiographs and CT images were reviewed for the presence of IVP. Preoperative and postoperative posterior disc height (PDH), anterior disc height (ADH), and SL were measured at disc levels with IVP and compared with those at disc levels without IVP using the t-test. Linear regression was used to evaluate the factors that predict changes in PDH, ADH, and SL. RESULTS One hundred forty patients with 247 disc levels between L-1 and L-5 were treated with lateral lumbar interbody fusion. Among all disc levels treated, the mean PDH increased from 3.69 to 6.66 mm (p = 0.011), the mean ADH increased from 5.45 to 11.53 mm (p < 0.001), and the mean SL increased from 9.59° to 14.55° (p < 0.001). Significantly increased PDH was associated with the presence of IVP, addition of pedicle screws, and lack of cage subsidence; significantly increased ADH was associated with the presence of IVP, anterior longitudinal ligament (ALL) release, addition of pedicle screws, and lack of subsidence; and significantly increased SL was associated with the presence of IVP and ALL release. CONCLUSIONS IVP in patients with degenerative spinal disease remains grossly underreported. The data from the present study suggest that the presence of IVP results in increased restoration of disc height and SL.

Restoration of Segmental Lordosis and Related Factors in Interbody Fusion for Degenerative Lumbar Disease

Restoration of Segmental Lordosis and Related Factors in Interbody Fusion for Degenerative Lumbar Disease

Clinical and radiological outcomes of unilateral transforaminal lumbar interbody fusion

Background Interbody fusion techniques provide solid fixation, maintain the load-bearing capacity of the spine, maintain proper disc and foraminal heights, have higher fusion rates, and prevent implant failure. Unilateral transforaminal lumbar interbody fusion (TLIF) is a one-stage posterior approach to the disc space that allows unilateral larger cage insertion without violation of the spinal canal by avoiding dural retraction, which is advantageous in revision cases and in higher lumbar levels above L3. Aim The aim of the study was to describe the technique and study the clinical and radiological results of unilateral TLIF. Study design This is a retrospective study on 40 patients with different etiologies treated by unilateral TLIF. Patients and methods A retrospective analysis was performed on 40 patients who had undergone unilateral TLIF during the period from April 2006 to December 2008 for chronic low back pain and radicular leg pain of different etiologies, including isthmic and degenerative spondylolisthesis, and revision cases with failed conservative treatment of more than 3 months. Radiographic assessment was carried out by means of anteroposterior, lateral, and dynamic flexion-extension plain radiographs and MRI. Bony fusion was assessed using the Bridwell anterior fusion grading system. Functional assessment was made using the visual analogue scale (0-10) for back and leg pain and the Oswestry Disability Index questionnaire. Results Unilateral TLIF achieves statistically significant reduction in spondylolisthesis from an average of 35.55 ± 11.62% preoperatively to an average of 3.49 ± 3.29% postoperatively with minimal change seen at final follow-up with restoration of segmental lordosis in all patients. Disc and foraminal heights were restored and corrected from an average of 7.24 ± 1.30 and 13.53 ± 1.91 mm, respectively, preoperatively to 11.80 ± 1.075 and 19.76 ± 1.79 mm, respectively, postoperatively without significant change at last follow-up. Ninety percent of patients had G1 bony fusion and 10% had G2 bony fusion. No patient had G3 or G4 fusion. All patients showed significant postoperative improvement in leg and back pain immediately postoperatively and at last follow-up. Leg pain improved from 7.24 ± 0.61 to 2.26 ± 0.84 SD postoperatively and to 0.65 ± 0.70 SD at last follow-up, and back pain improved from 7.78 ± 0.86 to 2.76 ± 0.89 SD postoperatively and to 0.98 ± 0.75 SD at last follow-up. The average preoperative Oswestry Disability Index score improved from 54.95 ± 7.02 to 10.73 ± 3.28 SD at last follow-up. There were no major intraoperative complications. Conclusion Unilateral TLIF s a safe and effective technique. It provides good clinical and radiological outcomes in different lumbar spinal pathologies. It is especially effective and safe in revision cases with epidural fibrosis when the standard posterior lumbar interbody fusion technique is contraindicated.

Acute Contralateral Radiculopathy after Unilateral Transforaminal Lumbar Interbody Fusion.

ObjectiveCases of contralateral radiculopathy after a transforaminal lumbar interbody fusion with a single cage (unilateral TLIF) had been reported, but the phenomenon has not been explained satisfactorily. The purpose of this study was to determine its incidence, causes, and risk factors.MethodsWe did retrospective study with 546 patients who underwent a unilateral TLIF, and used CT and MRI to study the causes of contralateral radicular symptoms that appeared within a week postoperatively. Clinical and radiological results were compared by dividing the patients into the symptomatic group and asymptomatic group.ResultsContralateral symptoms occurred in 32 (5.9%) of the patients underwent unilateral TLIF. The most common cause of contralateral symptoms was a contralateral foraminal stenosis in 22 (68.8%), screw malposition in 4 (12.5%), newly developed herniated nucleus pulposus in 3 (9.3%), hematoma in 1 (3.1%), and unknown origin in 2 patients (6.3%). 16 (50.0%) of the 32 patients received revision surgery. There was no difference in visual analogue scale and Oswestry disability index between the two groups at discharge. Both preoperative and postoperative contralateral foraminal areas were significantly smaller, and postoperative segmental angle was significantly greater in the symptomatic group comparing to those of the asymptomatic group (p<0.05).ConclusionThe incidence rate is not likely to be small (5.9%). If unilateral TLIF is performed for cases when preoperative contralateral foraminal stenosis already exists or when a large restoration of segmental lordosis is required, the probability of developing contralateral radiculopathy is increased and caution from the surgeon is needed.

Bilateral tubular minimally invasive surgery for low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS): analysis of a series focusing on postoperative sagittal balance and review of the literature.

To report our early experience with minimally invasive surgery (MIS) in low-dysplastic lumbosacral lytic spondylolisthesis (LDLLS), and to analyze the impact of surgery on postoperative spino-pelvic and sacro-pelvic parameters. Eight patients (mean age 47.6years) underwent MIS for LDLLS involving in all but one the L5-S1 level. VAS and ODI were used for clinical assessment. Imaging included pre-operative X-rays, CT and MRI scans. Post-operatively, all patients underwent X-rays and CT-scans. Pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS) values as well as lumbar lordosis (LL) have been derived from pre- and post-operative standard X-rays. Mean follow-up is 30.12months (range 15-42). No complications related to the surgical procedure were observed. Patients reported a satisfactory clinical outcome, as demonstrated by variation in mean VAS (from 9.1 to 3.6) and ODI (from 70.50 to 28.25%) scores. Comparison between pre- and post-operative sacro-pelvic parameters documented moderate changes, with reduction of PT and increase of SS in all but one patient. Overall sagittal balance of the spine has been evaluated using the sagittal vertical axis (SVA), obtained from post-operative X-rays. Mean value of SVA demonstrated a good sagittal balance of the spine. This series demonstrates that MIS is feasible and effective for LDLLS, as witnesses by the satisfactory clinical results maintained at medium-term follow-up. We submit that TLIF is a valid option but an adequately sized and positioned interbody cage is a key factor to allow satisfactory restoration of segmental lordosis.

Radiographic Analysis of PEEK Cage and FRA in Adult Spinal Deformity Fused to Sacrum

Retrospective radiographic study. To radiographically evaluate sagittal plane profile and fusion rates of polyetheretherketone (PEEK) cages versus femoral ring allografts (FRAs) in patients with adult spinal deformity fused to the sacrum. FRAs have been widely used in various degenerative lumbar spine disorders and in adult deformity to achieve interbody fusions with promising results. PEEK cages have gained increasing popularity of late; however, there is little documentation to the radiographic comparisons between PEEK cages and FRAs used in patients with adult spine deformity treated with long fusions to the sacrum. From March 2006 to February 2010, we analyzed 48 patients (mean age, 56.3±13.9 y) of 61 consecutive adult patients with global coronal and sagittal adult spine deformities who underwent first stage ALIF using PEEK cages or FRAs at L4-L5, L5-S1 segments followed by long (>6 levels) posterior instrumentation. PEEK cages and FRAs were used randomly according to surgeon's preference. Two independent observers retrospectively evaluated preoperative and postoperative disk height, foraminal height, segmental lordosis, and the interbody fusion rates at different postoperative intervals. Both PEEK cages and FRAs significantly (P<0.05) maintained disk space height at all follow-up times. PEEK cages maintained foraminal height and segmental lordosis, especially at L4-L5 better than FRAs at the final follow-up. At the final follow-up, PEEK cages achieved 94.9% of fusion rate, which was significantly (P<0.05) superior to FRA (84.2%), and PEEK cages were superior to FRAs in attaining earlier solid fusion. The Prolo functional scores of FRAs or/and PEEK cages were significantly improved at the final follow-up and did not show a significant difference between them. Both PEEK cages and FRAs can significantly increase disk space height and achieve similar clinical outcomes in treating adult spinal deformity fused to the sacrum. The radiographic results of PEEK cages were superior to FRAs in terms of an earlier solid fusion, and greater restoration of segmental lordosis.

Lumbar-sacral fusion by a combined approach using interbody PEEK cage and posterior pedicle-screw fixation: Clinical and radiological results from a prospective study

This prospective series evaluated the clinical and radiological results of a circumferential lumbar fusion achieved by a combined approach in one stage (anterior then posterior) using interbody PEEK cages and posterior pedicle-screw fixation. The combined approach in one stage is a safe and efficient technique with few complications to achieve a fusion with a satisfying clinical and radiological outcome. Thirty-nine consecutive patients were prospectively included, with a one-year clinical and radiological minimum follow-up, from December 2008 to July 2011. All patients suffering from degenerative disc disease or low-grade isthmic spondylolisthesis requiring L5S1, L4L5 or L4S1 spinal fusions were included. Clinical outcome was assessed using VAS, ODI and Rolland-Morris scores. Radiological outcome was assessed by analyzing PI, PT, lumbar lordosis, segmental lordosis, disc height, C7/CSFD ratio on full spine radiographies and the quality of bone fusion on a CT scan at 1-year follow-up. Blood loss, surgery time and adverse events were also recorded. Twenty-nine patients (74%) were operated for a lumbar degenerative disc disease and 10 patients (26%) for an isthmic spondylolisthesis. Mean age was 46 (± 10.1) years old. Clinical outcome were satisfactory. VAS, ODI and Rolland-Morris scores substantially improved. Mean follow-up was 22.5 months (± 8.7). Mean surgery time was 227 min (± 41.4) for complete surgical procedure time. Mean blood loss was 308 mL (± 179.2) for total surgery. Fusion was assessed in all cases. Disc height and segmental lordosis significantly improved in postoperative. The segmental lordosis at operated level(s) increased by 8.5° (± 5) regardless of the level, and by 11.6° (± 6) for L5-S1. The combined procedure meets the requested criteria for a lumbar fusion in terms of clinical and functional results, fusion rates, and restoration of segmental lordosis. It cumulates the advantages of the anterior and posterior approach performed alone and should be considered by surgeons before realizing a lumbar fusion.

O-17-241 - Monopolar motor cortex stimulation: A new mapping technique?

The fusion rate in spinal surgery may vary in relation to the technique, and it remains unknown which surgical technique provides the best fusion rate and surgical outcome. We aimed to compare radiologic and surgical results between 3 surgical techniques used for lumbar interbody fusion.Participants included 77 patients diagnosed with degenerative spinal stenosis including spondylolytic spondylolisthesis. Patients were divided into 3 groups according to surgical technique: anterior lumbar interbody fusion (ALIF, n = 26), transforaminal lumbar interbody fusion (TLIF, n = 21), and posterior lumbar interbody fusion (PLIF, n = 30). Various radiologic parameters were measured, including fusion rates.Significant changes after surgery were observed in the ALIF group for the percentage of vertebral body slippage, anterior disk height, posterior disk height, and segmental range of movement (ROM). The fusion rate on computed tomography (CT) scan at the final follow-up was 69.2% in the ALIF group, 72.7% in the TLIF group, and 64.3% in the PLIF group. The cage subsidence rate 2 years after surgery was 15.4% in the ALIF group, 38.1% in the TLIF group, and 10% in the PLIF group.ALIF was associated with better restoration of segmental lordosis. The fusion rate on CT scan and with segmental ROM did not differ between the 3 groups. TLIF was associated with a better postoperative visual analog scale. PLIF showed the lowest cage subsidence rate. Therefore, it is difficult to know which surgical technique is better among the 3 groups because each surgical method has its own advantages.