Segmental Lordosis Research Articles

Expandable Versus Static Cages for Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spondylosis

Objective: Expandable cages have been used in lumbar interbody fusion in recent years. These cages allow a customizable fit within the intervertebral space, enabling surgeons to restore alignment and disc height. Various types of expandable cages are currently available. However, the benefits of expandable titanium cages remain unclear, with limited evidence.Methods: This prospective, single-center cohort study enrolled patients undergoing transforaminal lumbar interbody fusion with expandable or static cages by a single surgeon. Titanium expandable cages were used in the intervention group, while polyetheretherketone static cages were applied in the control group. The clinical and radiological outcomes were evaluated preoperatively and at 1, 3, and 6 months postoperatively. The fusion rate assessed by dynamic radiography was significantly higher for the expandable cage group than in the static cage group at a 6-month follow-up (95% vs. 65%). The radiological outcomes, including disc height index, segmental lordosis, and lumbar lordosis, were similar in the 2 groups. There was no significant difference in the subsidence rate.Results: There were 20 patients in each group, with similar patient characteristics. The visual analogue scales for back and leg pain significantly improved in both groups. There were no significant differences between the groups in clinical outcomes.Conclusion: The expanded cages led to comparable outcomes. The subsidence rate of the titanium expandable cages was similar to that of the static cages. The newly designed expandable cage may accelerate fusion by reducing iatrogenic injuries to the endplate.

Defining modern iatrogenic flatback syndrome: examination of segmental lordosis in short lumbar fusion patients undergoing thoracolumbar deformity correction.

Understanding the mechanism and extent of preoperative deformity in revision procedures may provide data to prevent future failures in lumbar spinal fusion patients. ASD patients without prior spine surgery (PRIMARY) and with prior short (SHORT) and long (LONG) fusions were included. SHORT patients were stratified into modes of failure: implant, junctional, malalignment, and neurologic. Baseline demographics, spinopelvic alignment, offset from alignment targets, and patient-reported outcome measures (PROMs) were compared across PRIMARY and SHORT cohorts. Segmental lordosis analyses, assessing under-, match, or over-correction to segmental and global lordosis targets, were performed by SRS-Schwab coronal curve type and construct length. Among 785 patients, 430 (55%) were PRIMARY and 355 (45%) were revisions. Revision procedures included 181 (23%) LONG and 174 (22%) SHORT corrections. SHORT modes of failure included 27% implant, 40% junctional, 73% malalignment, and/or 28% neurologic. SHORT patients were older, frailer, and had worse baseline deformity (PT, PI-LL, SVA) and PROMs (NRS, ODI, VR-12, SRS-22) compared to primary patients (p < 0.001). Segmental lordosis analysis identified 93%, 88%, and 62% undercorrected patients at LL, L1-L4, and L4-S1, respectively. SHORT patients more often underwent 3-column osteotomies (30% vs. 12%, p < 0.001) and had higher ISSG Surgical Invasiveness Score (87.8 vs. 78.3, p = 0.006). Nearly half of adult spinal deformity surgeries were revision fusions. Revision short fusions were associated with sagittal malalignment, often due to undercorrection of segmental lordosis goals, and frequently required more invasive procedures. Further initiatives to optimize alignment in lumbar fusions are needed to avoid costly and invasive deformity corrections. IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Cervical Lordosis Correction and Segmental Height in Anterior Cervical Surgeries; The Role of Implant Choice

This study aims to compare the impact of three surgical techniques-stand-alone cage placement (SAC), anterior cervical plate (ACP) fixation, and total disc replacement (TDR)-on cervical lordosis restoration and segmental height after anterior cervical discectomy at C5-6 level. To eliminate the effect of lordosis between different levels, patients operated on at the same level were included in the study. Restoring cervical lordosis is crucial for improving patient outcomes, including pain reduction and preventing mechanical complications. A retrospective screening of 89 patients who underwent single-level C5-6 surgery between 2011 and 2021 was analyzed. Patients were categorized into three groups based on the surgical technique used: SAC, ACP, or TDR. Lordotic angles and segmental heights were measured preoperatively, first-month follow-up, and at the 24-month follow-up. Statistical analysis was conducted using the Wilcoxon Signed Rank test and ANOVA, with a significance threshold set at P<.05. All three techniques resulted in significant early and late postoperative increases in both global and segmental lordosis. The early postoperative height gain was most pronounced in the ACP group. However, no significant differences in lordosis or height preservation were observed among the groups at the 24-month follow-up. These findings align with previous studies, indicating comparable long-term outcomes across these surgical approaches. Stand-alone cage placement, anterior cervical plate fixation, and total disc replacement all effectively restore cervical lordosis and segmental height after anterior cervical discectomy at the C5-6 level. Despite early differences, the long-term results were similar, suggesting that the choice of technique should be based on individual patient needs and specific surgical considerations.

The Implications of Sacralized Transitional Vertebra on Spinal Alignment.

Retrospective study of a multicentric prospective database. This study aimed to determine, in a cohort of healthy volunteers, the impact of sacralized lumbo-sacral transitional vertebra (LSTV) on spinal alignment according to its grade, particularly regarding lumbar lordosis magnitude and distribution, and the implications for spinopelvic parameters measurement. There is little data regarding spinopelvic alignment assessment in LSTV patients. This study included healthy volunteers with full-body stereoradiographs in free-standing position aged over 18. Castellvi grade, pelvic parameters (measured on S1 and L5), L1-S1 lumbar lordosis (LL) and segmental lordosis for each disc and vertebral body, thoracic kyphosis, cervical lordosis, lower limb, and global alignment parameters were assessed. Castellvi I and II were considered as Low-grade and Castellvi III and IV as High-grade LSTV. Alignment parameters between No-LSTV, Low- and High-grade LSTV were compared. Propensity score matching was used to match PI in No-LSTV and Low-grades. Spinopelvic parameters measured on S1 in No-LSTV group and on L5 in High-grade were compared. 713 subjects were included, of whom 23 Low-grades and 27 High-grades. Mean pelvic incidence was 51.0±11.0° and mean age was 37.5±16.2 years. LL distribution was different between groups, with an apex and inflexion point significantly higher in High-grade (P<0.001). Kyphosis in the LSTV segment was compensated for by a steeper increase of LL above L5 in the High-grades. Low-grades and PI-matched No-LSTV presented similar alignment parameters. There were minor differences in parameters measured on S1 in No-LSTV and no L5 in High-grades. Subjects with low-grade LSTV present similar alignment as PI-matched No-LSTV subjects, and S1 should be taken as reference to measure spinopelvic parameters. High-grade LSTV subjects have kyphotic L5-S1 segment with more cranial lumbar apex and thoracolumbar inflexion point. In these subjects, spinopelvic parameters should be measured on L5.

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°).

Sagittal morphometry of intervertebral spaces in subaxial cervical region of asymptomatic Chinese.

This study aimed to quantify and evaluate morphology of intervertebral space between neighboring cervical units using radiographic imaging indices, to help spine surgeons when performing anterior cervical discectomy and fusion (ACDF) surgery on the Chinese population. The background and imaging parameters of the subjects were assessed. Cervical lateral radiographs were employed to measure the intervertebral height (IH), intervertebral height index (IHI), and segmental lordosis (SL). Endplate parameters measurements were conducted on sagittal T2-weighted magnetic resonance imaging (MRI), including endplate sagittal diameter (ESD), and endplate concavity depth (ECD). All individuals were divided into three age groups: individuals aged 20-35 were in group A, individuals aged 36-50 were in group B, and individuals aged over 50 were in group C. A comparison of the variables was conducted among the three groups. Additionally, these radiographic parameters were also compared between males and females. A total of 102 individuals were included in this study. IH was greater at C6/7 than those at other segmental levels (p < 0.001). The largest SL values were found at C6/7, while the least were found at C3/4. The superior ESD (ESDs) and ECD (ECDs) of the intervertebral space were significantly greater than those of the inferior endplates (p < 0.05). The ESD and ECD values were the largest at C6/7, while the least at C3/4. Additionally, age and gender had an influence on several parameters. IH was significantly lower in group A compared to group B (p < 0.05) and group C (p < 0.05) from C3/4 level to C6/7 level. ECDs were lower in group A compared to group B (p < 0.05) and group C (p < 0.05) at each level. IH and ESD in males were generally significantly greater than those in females at all levels (p < 0.05). The current study found that C6/7 had the greatest IH, SL, ESD, and ECD values in asymptomatic Chinese. SL gradually increased from C3/4 to C6/7 levels. IH and ECD were significantly associated with age. Males had greater IH and ESD values than females. These findings provide baseline information for planning for selection of anterior screws and intervertebral implants.

Could indirect decompression occur for cord compression by the ligamentum flavum with anterior cervical discectomy and fusion?

Cord compression by the ligamentum flavum (CCLF) has been reported to adversely affect the clinical outcomes of anterior cervical discectomy and fusion (ACDF). While indirect decompression does occur for foraminal stenosis with ACDF, whether ACDF could improve CCLF with the distraction of disc space remains unclear. This study aimed to identify 1) whether indirect decompression occurs for CCLF with ACDF, and 2) risk factors that hinder the improvement of CCLF. This retrospective cohort study included 119 patients who underwent ACDF for the treatment of cervical myelopathy and CCLF was detected on preoperative MRI. Patients who demonstrated improvement in CCLF grade after ACDF were included in the improved group, while those who did not show improvement were classified as the unimproved group. Patient characteristics, cervical sagittal parameters, neck and arm pain visual analog scale score, and Japanese Orthopaedic Association (JOA) score were assessed. A comparison between the improved and unimproved groups was performed. Regression analyses were performed to identify factors associated with CCLF grade improvement. Overall, 58.0% (69/119) of patients showed improvement in CCLF grade after ACDF. CCLF grade did not improve in the remaining 42.0% (50/119) of patients, and 3.4% (4/119) of patients experienced aggravation of CCLF after ACDF. Preoperative spondylolisthesis (OR 0.252, 95% CI 0.090-0.711; p = 0.009) and greater segmental lordosis 3 months postoperatively (OR 0.835, 95% CI 0.731-0.953; p = 0.008) were the factors that hindered the improvement of CCLF after ACDF. Furthermore, patients with higher pre- or postoperative CCLF grades showed significantly less improvement in JOA score 2 years postoperatively. Indirect decompression for CCLF with ACDF is not reliable because 42.0% of patients did not demonstrate improvement in CCLF grade after the operation. Preoperative spondylolisthesis and postoperative increased segmental lordosis were risk factors for failure of CCLF improvement. Both pre- and postoperative higher CCLF grades were associated with poor neurological recovery 2 years postoperatively.

A Comparative Study between Single-Level Oblique Lumbar Interbody Fusion with Transforaminal Lumbar Interbody Fusion for Lumbar Adjacent Segment Disease.

Background/Objectives: Various surgical approaches have been proposed for treating adjacent segment disease (ASD) after lumbar fusion. However, studies using oblique lumbar interbody fusion (OLIF) to treat ASD are lacking. The current study assessed the postoperative outcomes of single-level OLIF for ASD, comparing the results with those for patients undergoing transforaminal lumbar interbody fusion (TLIF). Methods: Patients who underwent single-level OLIF or TLIF for lumbar ASD were retrospectively included. Clinical outcomes, that is, the results of assessments using the Euroqol 5-Dimension quality of life scale (EQ-5D), the Oswestry Disability Index, and the visual analog scale, were evaluated. Radiologic parameters, including disc height (DH), segmental lordosis (SL), segmental coronal angle (SCA), lumbar lordosis, and pelvic incidence-lumbar lordosis mismatch, were also assessed. Results: A total of 65 patients were enrolled: 32 in the OLIF group and 33 in the TLIF group. The median follow-up time was 24.0 months in both groups. The clinical outcomes and radiologic parameters significantly improved in both groups postoperatively. According to intergroup comparisons, the OLIF group had significantly less blood loss and superior improvement in radiologic parameters (DH, SL, and SCA) whereas the TLIF group had significantly shorter operation times. For the OLIF patients who did not undergo posterior decompression, the operation time was similar to that of the TLIF group, but the surgical blood loss and length of hospital stay were significantly reduced compared with the TLIF group. Conclusions: Compared with TLIF, OLIF provides similar clinical outcomes, leads to less surgical blood loss, and has superior radiologic parameters; however, the operation time is significantly longer. OLIF without posterior decompression may be a superior option to TLIF for certain patients.

Effect of Cage Material and Size on Fusion Rate and Subsidence Following Biportal Endoscopic Transforaminal Lumbar Interbody Fusion.

Biportal endoscopic transforaminal lumbar interbody fusion (BE-TLIF) is an emerging, minimally invasive technique performed under biportal endoscopic guidance. However, concerns regarding cage subsidence and sufficient fusion during BE-TLIF necessitate careful selection of an appropriate interbody cage to improve surgical outcomes. This study compared the fusion rate, subsidence, and other radiographic parameters according to the material and size of the cages used in BE-TLIF. In this retrospective cohort study, patients who underwent single-segment BE-TLIF between April 2019 and February 2023 were divided into 3 groups: group A, regular-sized three-dimensionally (3D)-printed titanium cages; group B, regular-sized polyetheretherketone cages; and group C, large-sized 3D-printed titanium cages. Radiographic parameters, including lumbar lordosis, segmental lordosis, anterior and posterior disc heights, disc angle, and foraminal height, were measured before and after surgery. The fusion rate and severity of cage subsidence were compared between the groups. No significant differences were noted in the demographic data or radiographic parameters between the groups. The fusion rate on 1-year postoperative computed tomography was comparable between the groups. The cage subsidence rate was significantly lower in group C than in group A (41.9% vs. 16.7%, p=0.044). The severity of cage subsidence was significantly lower in group C (0.93±0.83) than in groups A (2.20±1.84, p=0.004) and B (1.79±1.47, p=0.048). Cage materials did not affect the 1-year postoperative outcomes of BE-TLIF; however, subsidence was markedly reduced in large cages. Larger cages may provide more stable postoperative segments.

Impact of Segmental Lordosis Restoration During Degenerative Spinal Fusion on Two-Year Adjacent Segment Disease and Revision Rates.

Retrospective cohort study. Assess the impact of inadequate correction of L4-S1 lordosis during transforaminal lumber interbody fusion (TLIF) on adjacent segment disease and revision rates. Restoring alignment is an important consideration in spinal fusions. Failure to correct to level-specific alignment goals could promote the development of adjacent segment disease. As such, it is crucial to investigate the role of sagittal segmental alignment on clinical outcomes following short segment lumbar fusion. Patients who underwent 1- to 3-level transforaminal lumbar interbody fusion (TLIF) and had two-year outcomes data were included in this retrospective cohort study. Segmental lumbar lordosis was assessed in all patients with L3-L4, L4-L5, and L5-S1 constructs. Demographics, radiographic spinopelvic alignment, and complications were compared in a sub-group of patients fused at L4-S1 with adequate (i.e., within 35-45°) and inadequate (i.e., <35°) L4-S1 lordosis. Among the 168 included patients, mean age was 61.7 years, 56.0% were female, and mean follow-up was 32.3 months. Segmental lumbar lordosis did not change significantly after TLIF of L3-L4, L4-L5, or L5-S1 (P>0.05). Two-year postoperatively, 32.7% developed adjacent segment disease and 19.6% underwent revisions. After stratification by adequate (N=15) or inadequate (N=54) restoration of L4-S1 lordosis following initial TLIF surgery, adequately-restored patients had higher preoperative L4-S1 lordosis (Adequately-Restored=39.3° vs Inadequately-Restored=29.5°, P<0.001) and lower two-year postoperative adjacent segment disease (6.7% vs. 33.3%, P=0.032) and revision (5.7% vs. 25.9%, P=0.l33) rates. Adjacent segment disease patients had higher implant-related complications (Adjacent Segment Disease=36.8% vs No Adjacent Segment Disease=8.0%, P=0.008) and subsequent revisions (61.1% vs. 8.7%, P<0.001). Adjacent segment disease and revisions after degenerative lumbar spinal fusion are common. In this cohort, suboptimal restoration of L4-S1 lordosis was associated with higher rates of adjacent segment disease and subsequent revisions, thus highlighting the importance of restoring sagittal alignment in degenerative spine surgery. III.

Minimally-invasive trans-facet lumbar interbody fusion using a dual-dimension expandable cage: preliminary results of a multi-institutional retrospective study.

Minimally-invasive trans-facet lumbar interbody fusion (LIF) is an emerging technique that offers the advantages of being safe, enabling decompression, and facilitating patient recovery. An innovative cage that expands in two dimensions has been introduced to restore segmental lordosis and disc height while minimizing the risk of cage subsidence. This study aimed to report our surgical technique of trans-facet LIF utilizing the innovative cag and to report the early clinical outcomes. We retrospectively reviewed the medical records and radiographs of patients who underwent trans-facet LIF with dual-dimension expandable cages from two institutions: Duke University Hospital and Vail-Summit Orthopaedics and Neurosurgery. The analysis covered patient demographics, Oswestry Disability Index (ODI), visual analogue scale (VAS) for back pain, surgical data, complications, and radiographic parameters. Clinical outcomes were compared between pre- and one year post-operation, while radiographic outcomes were compared between pre- and three months post-operation. Twenty patients with a mean age of 61.2 years were included. Seventeen patients (85.0%) had spondylolisthesis, and L4/5 (68.2%) was the most common pathology level. Twelve patients (60.0%) underwent awake surgery, and the mean operative time was 164.5±36.1 minutes, with an estimated blood loss of 64.0±39.5 mL and a hospital stay of 1.75±1.2 days. Four patients (20.0%) experienced cage subsidence; however, none required additional surgery. The VAS score significantly improved from a preoperative average of 7.3±2.7 to 2.6±1.6 one year post-operation (P=0.02). The ODI score also showed a significant decrease, from 48.7±22.9 preoperatively to 16.4±11.1 one year postoperatively (P=0.03). Notably, 80% and 83.3% of patients achieved the minimum clinically important difference in VAS and ODI scores, respectively. The degree of spondylolisthesis was significantly reduced from a median of 5.9 mm preoperatively to 0 mm postoperatively (P<0.001). Additionally, both anterior and posterior disc heights significantly increased after surgery, from 9.8±4.7 to 15.1±2.6 mm (anterior) and from 4.9±3.3 to 10.5±2.2 mm (posterior) (P<0.001 for both). The mean segmental lordosis increased by 2.9 degrees and was associated with cage height (P=0.03), while spinopelvic parameters remained unchanged. Minimally-invasive trans-facet LIF with dual-dimension expandable cages demonstrates a substantial capacity for spondylolisthesis reduction and disc height restoration, and provides good short-term clinical outcomes. It may be the most appropriate method for deploying this large cage as it allows for a large, unobstructed pathway to the disc. However, future studies are needed to determine the long-term outcomes, including the arthrodesis rate.

The Utility of Magnetic Resonance Imaging-based Vertebral Bone Quality Scores as a Predictor of Cage Subsidence Following Transforaminal and Posterior Lumbar Interbody Fusion.

Retrospective study. The objectives were to determine whether vertebral bone quality (VBQ) scores are associated with interbody cage subsidence following transforaminal (TLIF) and posterior (PLIF) lumbar interbody fusions and whether there is a clinically sensitive threshold for subsidence. Interbody cage subsidence following lumbar fusion is a complication that can generate poor surgical outcomes. Prior research has correlated cage subsidence with bone mineral density. VBQ scores derived from magnetic resonance imaging (MRI) have been proposed as a tool for measuring bone mineral density, offering a potential new and convenient preoperative risk assessment tool for subsidence. The study involved patients undergoing single-level PLIF or TLIF between 2007 and 2022. Exclusions were for nondegenerative diagnoses, multilevel/revision surgeries, inadequate radiographs, missing immediate postoperative radiographs, and preoperative MRI studies older than 1 year. VBQ was calculated at L1-L4 from preoperative T1-weighted MRI images. Subsidence was assessed by changes in disc height (DH; >2mm difference) and segmental lordosis (SL; >5 degrees difference) between immediate weight-bearing postoperative and latest postoperative lateral radiographs. Statistical analysis included descriptive and inferential statistics. Subsidence was observed in 27% (SL parameter) and 47% (DH parameter) of 51 total patients. VBQ scores were significantly associated with cage subsidence based on both SL (odds ratio = 7.750, P = 0.012; correlation coefficient = 0.382, P = 0.006) and DH (odds ratio = 4.074, P = 0.026; correlation coefficient = 0.258, P = 0.057) in the combined TLIF/PLIF cohorts. In the cohort of 36 patients undergoing TLIF, a VBQ of 2.70 yielded 100.0% sensitivity and 46.2% specificity in detecting subsidence with SL measurement (area under the curve = 0.812, P < 0.001) and 86.7% sensitivity and 47.6% specificity with the DH measurement (area under the curve = 0.692, P = 0.033). We found that MRI-based VBQ scores are effective predictors of cage subsidence following TLIF surgery. A VBQ score of 2.70 demonstrated a reliable model and high sensitivity for doing so, identifying a potential clinical threshold for preoperative subsidence risk assessment. Level III.

Prone Single Position Approach to Lateral Lumbar Interbody Fusion: Systematic Review and Meta-Analysis.

Lateral lumbar interbody fusion (LLIF) with posterior screw fusion is a safe and effective treatment for patients suffering from degenerative spine disorders. While LLIF has been shown to restore disc height, decompress neural components, correct sagittal imbalances, and improve pain scores, the approach requires repositioning patients for posterior pedicle fixation, which requires 2 separate surgeries. The evolution of surgical techniques, navigation, and robotics has allowed for a single position approach to LLIF with the patient in the prone position. The purpose of this study was to perform a systematic review and meta-analysis comparing the prone single position (PSP) LLIF approach to the dual position LLIF approach. We hypothesized that PSP LLIF will have a reduced operative time, complication rate, and blood loss compared with the dual position LLIF procedure. A systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. PubMed and Embase databases were searched with key terms: (lateral AND [interbody OR "inter body"] AND lumbar AND fusion) AND (prone OR single). Results were extracted and reviewed by 2 authors (MR and RB) per selection criteria. Patient demographics were extracted from the selected studies, along with surgical, patient-reported, and radiographic outcomes. A meta-analysis was performed using an unstandardized mean difference or log odds ratio with a confidence level of 95%. Fifteen studies were included in the systematic review and 5 studies compared PSP LLIF to dual position LLIF for meta-analysis. PSP LLIF had a reduced operative time and length of stay compared with the dual position approach, although there was no significant reduction in estimated blood loss. Additionally, PSP LLIF improved lumbar lordosis more effectively than dual position LLIF. There was no difference in segmental lordosis or pelvic tilt. There was no difference in intraoperative complications, postoperative complications, or reoperations. PSP LLIF reduces operative time and length of stay, with no relative increase in complications or reoperations compared with the dual position approach. Additionally, PSP LLIF improves lumbar lordosis relative to dual position LLIF, which may improve functional outcomes and reduce the risk of developing adjacent segment disease. The associated operative and postoperative benefits of PSP LLIF may improve long-term outcomes of patients undergoing spinal fusion.

Comparative Biomechanical Analysis of Anterior Lumbar Interbody Fusion and Bilateral Expandable Transforaminal Lumbar Interbody Fusion Cages: A Finite Element Analysis Study.

Expandable transforaminal lumbar interbody fusion (TLIF) cages could offer an alternative to anterior lumbar interbody fusion (ALIF). Bilateral cage insertion enhances endplate coverage, potentially improving stability and fusion rates and maximizing segmental lordosis. This study aims to compare the biomechanical properties of bilateral expandable TLIF cages to ALIF cages using finite element modeling. We used a validated 3-dimensional finite element model of the lumbar spine. ALIF and TLIF cages were created based on available product data. Our focus was on analyzing spinal motion in the sagittal plane, evaluating forces transmitted through the vertebrae, and comparing an ALIF model with various TLIF cage models. The largest TLIF cage model exhibited a 407.9% increase in flexion motion and a 42.1% decrease in extension motion compared with the ALIF cage. The second largest TLIF cages resulted in more flexion motion and less extension motion compared with ALIF, while smaller cages were inferior to ALIF. ALIF cages were associated with increased adjacent segment motion compared with TLIF cages, primarily in extension. Endplate stress analysis revealed higher stress in the ALIF cage model with a more uniform stress distribution. ALIF cages excel in stabilizing L5 to S1 during flexion, while largest TLIF cages offer superior stability in extension. Large bilateral TLIF cages may provide biomechanical stability comparable to ALIF, especially in extension and could potentially reduce the risk of adjacent segment disease with lower adjacent segment motion.

Expandable versus static transforaminal lumbar interbody fusion (TLIF) cages: comparing radiographic outcomes and complication profiles

Background ContextExpandable transforaminal lumbar interbody fusion (TLIF) cages have become popular in recent years due to anticipated advantages of increased disc height, improved segmental lordosis, and ease of implantation. Such benefits have not been conclusively demonstrated in the literature. PurposeTo determine whether expandable cages increase disc height and segmental lordosis in a durable way following surgery and compare complication profiles between cage types. Study Design/SettingRetrospective cohort study conducted within a large academic health system involving 31 different spine surgeons. Patient SampleAdults undergoing single-level TLIF for an indication other than infection, tumor, trauma, or revision instrumentation from 2021 to 2023. Outcome MeasuresOur primary outcomes were changes in segmental disc height, segmental lordosis, and L4-S1 lordosis at 2 weeks, 6 months, and 1 year following surgery relative to baseline. Our secondary outcomes were frequencies of incidental durotomies, surgical site infections, readmissions, death, subsidence, and unplanned return to the operating room. MethodsRadiographic variables were collected from our institutional imaging registry. Demographics and surgical characteristics were abstracted from chart review. Generalized linear modeling was used for each primary outcome, with cage type (expandable vs. static) as our primary predictor and age, biologic sex, race, CCI, year of surgery, duration of surgery, invasiveness of surgery, surgeon specialty (Orthopedics vs. Neurosurgery), and level of surgery as covariates. ResultsOur cohort consisted of 417 patients with a mean age of 62. Static cages were used in 306 patients and expandable cages in 111. Expandable cages were associated with increased changes in disc height relative to static cages at 2 weeks (1.1 mm [0.2–1.9]; p=.01) and 6 months (1.2 mm [0.2–2.3]; p=.02) following surgery, but differences were no longer significant at 1 year (0.4 mm [−0.9–1.8]; p=.4). Expandable cages were found to subside more commonly than static cages (14.1% vs. 6.6%; p=.04). No significant differences between cage types were identified in lordotic parameters at any timepoint (p=0.25 to p=0.97). ConclusionsExpandable cages were associated with an initial increase in disc height relative to static cages, but this difference diminished with the first year of surgery, likely due to a higher rate of subsidence within the expandable cohort.

Single Position Prone Lateral Lumbar Interbody Fusion: A Review of the Current Literature.

Spinal fusion, vital for treating various spinal disorders, has evolved since the introduction of the minimally invasive Lateral Lumbar Interbody Fusion (LLIF) by Pimenta in 2001. Traditionally performed in the lateral decubitus position, LLIF faces challenges such as intraoperative repositioning, neurological complications, and lack of access to lower lumbar levels. These challenges lead to long surgery times, increased rates of perioperative complications, and increased costs. The more recently popularized prone lateral approach mitigates these issues primarily by eliminating patient repositioning, thereby enhancing surgical efficiency, and reducing operative times. This review examines the progression of spinal fusion techniques, focusing on the advantages and recent findings of the prone lateral approach compared to the traditional LLIF. The prone lateral approach has shown improved patient outcomes, including lower blood loss and shorter hospital stays, and has been validated by multiple studies for its safety and efficacy compared to the LLIF approach. Significant enhancements in postoperative metrics, such as the Oswestry Disability Index, Visual Analog Scale, and radiological improvements have been noted. Comparatively, the prone lateral approach offers superior segmental lordosis correction and potentially better subjective outcomes than the lateral decubitus position. Despite these advances, both techniques present similar risks of neurological complications. Overall, the prone lateral approach has emerged as a promising alternative in lumbar interbody fusion, combining efficiency, safety, and improved clinical outcomes.

Comparison of clinical and radiographic outcomes in unilateral transforaminal lumbar interbody fusion: a retrospective analysis of three surgical approaches.

The primary objective of this study is to evaluate and compare the clinical and radiographic outcomes of the combined spinous process-splitting approach with a Wiltse (SPSW) approach, the combined conventional approach with a Wiltse (CW) approach, and the conventional open (CO) approach in unilateral transforaminal lumbar interbody fusion (TLIF). The clinical outcomes were assessed, and intraoperative data and complications were collected. Numeric Rating Scale (NRS) scores for low back pain and leg pain, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) scores for evaluating functions of the lumbar spine and health-related quality of life, and the modified MacNab standard for assessing satisfaction were analyzed. Radiographic outcomes included disc space height, segmental lordosis, interbody fusion assessment, and the rate of muscle atrophy of the multifidus and the erector spinae muscles. Among the three groups, the SPSW group exhibited the shortest operation and drain retention time, lowest intraoperative blood loss, and minimal postoperative blood loss. Notably, the SPSW group displayed the highest level of social life function based on the JOABPEQ, and the highest level of patient satisfaction according to the modified MacNab Criteria, along with the lowest rate of muscle atrophy. All the SPSW, CW, and CO approach TLIF procedures achieved overall satisfactory effects of decompression and fusion for lumbar degenerative diseases. The SPSW approach procedure appears to be associated with the smallest surgical trauma and highest satisfaction because of reducing iatrogenic injury of the paraspinal muscles.

Changes in Alignment at Untreated Vertebral Levels Following Short-Segment Fusion Using Personalized Interbody Cages: Leveraging Personalized Medicine to Reduce the Risk of Reoperation.

An abnormal postoperative lordosis distribution index (LDI), which quantifies the ratio between the lordosis at L4 to S1 and the lordosis at L1 to S1, contributes to the development of adjacent segment disease and increased revision rates in patients undergoing short-segment lumbar intervertebral fusions. Incorporating preoperative spinopelvic parameters and LDI into the surgical plan for short-segment fusion is important for guiding alignment restoration and preserving normal preoperative alignment in unfused segments. This study examined changes in LDI, segmental lordosis, and lordosis of the unfused levels in patients treated with personalized interbody cage (PIC) implants. This retrospective study evaluated radiographic measurements from 111 consecutively treated patients diagnosed with degenerative spinal conditions and treated with a short-segment fusion of L4 to L5, L5 to S1, or L4 to S1 using PIC implant(s) within 6 months of the fusion procedure. Comparisons of intervertebral lordosis for treated and untreated levels as well as LDI pre- and postoperatively were performed. In patients with a preoperative hypolordotic distribution (LDI < 50%), statistically significant increases were found in LDI postoperatively, approaching the normal LDI range (LDI 50%-80%). Likewise, patients with hyperlordotic distribution preoperatively (LDI > 80%) experienced a decrease in LDI postoperatively, trending toward the normal range, although the changes were not statistically significant. Intervertebral lordosis for the L5 to S1 level increased significantly following the placement of a PIC in the normal and hypolordotic LDI groups. Changes in intervertebral lordosis for L5 to S1 were not significant for patients with preoperative hyperlordotic LDI. Reciprocal changes in intervertebral lordosis at L1 to L4 were not observed in any groups. PIC implants may provide a benefit for patients, particularly those with hypolordotic distributions preoperatively. They have the potential to further improve patient outcomes by helping surgeons to achieve patient-specific lordosis goals, which may help to reduce the risk of adjacent segment disease and revisions in patients undergoing short-segment lumbar intervertebral fusions. Personalized implants can help surgeons achieve patient-specific alignment goals, potentially prevent adjacent segment disease, and reduce long-term reinterventions.

Prospective Assessment of Transforaminal Lumbar Interbody Fusion (TLIF) in Spondylolisthesis: A Radiological and Functional Outcome Study in an Indian Population.

Spondylolisthesis is a common spinal condition in which one vertebra slips over another, leading to pain and disability. Transforaminal lumbar interbody fusion (TLIF) has emerged as a surgical option for addressing spondylolisthesis; however, limited research exists, especially in the Indian context, evaluating its radiological and functional outcomes. The study aimed to evaluate the radiological and functional outcomes of TLIF in spondylolisthesis using standardized scoring systems, to evaluate the sagittal balance of the spine radiologically in patients who have undergone TLIF for spondylolisthesis, and to evaluate the correlation between the functional and radiological outcomes after TLIF. This prospective observational study included spondylolisthesis patients undergoing TLIF at SRM Medical College Hospital and Research Centre from August 2022 to August 2024. Criteria included Meyerding grade 1-4 spondylolisthesis, single-segment fusion, and willingness for 12-month follow-up. Forty-five patients were included with age 36.6 ± 12.2 years, with 73.3% being female. L4-L5 is the most common level affected in 21 patients (46.7%). Significant improvements were observed in pelvic tilt 19.07 ± 2.05, sacral slope 30.6 ± 4.4, segmental lordosis 18.4 ± 1.4, lumbar lordosis 57.1 ± 1.8, sagittal vertical axis (SVA) 2.5 ± 0.3, Visual Analog Scale for pain 0.4 ± 0.5, and Oswestry Disability Index (ODI) scores 5.23 ± 2.6 postoperatively (p < 0.05). At one-year follow-up, 84.4% of patients had good-to-excellent outcomes, and 44.4% had definitive fusion according to modified Lee criteria. However, there was no correlation between ODI score and grade of listhesis, pelvic incidence (PI), or SVA of the spine (p > 0.05). This study provides valuable insights into the effectiveness of TLIF surgery in addressing spondylolisthesis, both in terms of radiological and functional outcomes. However, there was no correlation between improvement in functional and radiological parameters (PI vs. ODI, SVA vs. ODI). TLIF appears to offer significant improvements in patient well-being and quality of life. These findings contribute to understanding TLIF's suitability as a treatment for spondylolisthesis and can inform clinical practice, ultimately benefiting patients suffering from this condition.

P304. Transforaminal lumbar interbody fusion does not correct segmental lordosis, a factor related to the occurrence of adjacent segment disease

P304. Transforaminal lumbar interbody fusion does not correct segmental lordosis, a factor related to the occurrence of adjacent segment disease