Lumbar Interbody Fusion Cage Research Articles

Anterior Column Support With Anterior Lumbar Interbody Fusion Cage Through Posterior Approach Maneuver: A Technical Note and Preliminary Radiologic Report.

Retrospective cohort study. To evaluate the feasibility of anterior column support through a posterior approach using an anterior lumbar interbody fusion (ALIF) cage. Anterior fusion is an effective way to maintain spinal lordosis; however, it may be technically difficult in some cases. Conventional lumbar fusion and spinal deformity correction surgeries were performed using a conventional ALIF cage with a modified extratransforaminal lumbar interbody fusion (ExTLIF). Patients with 1 or 2 fusion levels were classified into group 1, and those with spinal deformity correction were classified into group 2. Radiologic parameters were evaluated during the follow-up periods. A total of 51 patients underwent this procedure. Thirty-five patients (19 male and 16 female, 69.4±9.6y old) with 37 fusion sites were in group 1, and 16 patients (3 male and 13 female, 71.4±5.7y old) were in group 2. The mean follow-up periods of groups 1 and 2 were 12.3±3.4 and 10.7±4.7 months, respectively. In group 1, the mean lumbar lordosis and segmental lumbar lordosis increased significantly during the last follow-up (39.9±13.0 and 20.6±6.0 degrees, respectively, both P<0.001), and the mean disc space also increased at the last follow-up (P<0.001). The same was observed in group 2 with significant increases in the mean lumbar lordosis and segmental lumbar lordosis at the last of the follow-up period (46.8±9.3 and 16.9±8.9 degrees, respectively, both P<0.001). The disc space also increased significantly (P<0.001). Fusion rates were 94.2% and 87.5% in groups 1 and 2, respectively, and the corresponding subsidence rates were 85.4% and 68.8%. In group 1, there was a significant correlation between subsidence and cage height (P=0.046). This procedure (ExTLIF) can be applied in cases where an anterior approach is contraindicated as well as for deformity correction. Level III.

Improved clinical and radiographic outcomes with expandable cages in transforaminal lumbar interbody fusion: a propensity-matched cohort analysis.

The restoration of sufficient overall lumbar lordosis (LL) and segmental LL (SL) is associated with achieving optimal sagittal balance, decreasing back pain, and enhancing functional outcomes for patients. Expandable cages were developed in hopes of improving radiographic parameters and clinical outcomes, although current clinical evidence is inconclusive. Here, the authors aimed to evaluate the clinical and radiographic outcomes in patients undergoing one- or two-level open transforaminal lumbar interbody fusion (TLIF) with expandable versus static cage placement, using propensity-matched cohorts. An institutional retrospective cohort of patients who underwent one- or two-level open TLIF with either expandable cage or static cage placement was identified. Using relevant preoperative covariates, including age, primary versus revision operation, number of cages implanted, and surgical level implanted, the authors built propensity-matched cohorts. They identified clinical outcomes in both cohorts, including operative characteristics and complication rates, along with pain, weakness, and sensory deficits over follow-up. Furthermore, they extracted and examined preoperative, postoperative, and last follow-up radiographic parameters. A total of 148 patients were included, and they were followed for a mean of 1.7 years (range 0.5-4.3 years). Propensity matching was used to create cohorts of patients who were similar with respect to age, surgical indication, revision status, number of cages implanted, surgical level implanted, and length of follow-up. Patients in both groups had similar preoperative radiographic parameters. Patients with expandable cages saw larger increases in SL, both postoperatively (5.3° ± 7.5° vs 1.6° ± 5.6°, p = 0.006) and at last follow-up (5.7° ± 7.4° vs 1.0° ± 6.1°, p = 0.003). They also saw significant improvements in pelvic incidence minus LL mismatch at last follow-up (-4.4° ± 13.2° vs 5.8° ± 13.8°, p = 0.009). No differences in intraoperative or perioperative complications were found, but patients with expandable cages were less likely to require readmission, develop adjacent-segment disease, or require revision surgery. They were also more likely to be symptom free at 1 month after surgery and at last follow-up. Expandable cages lead to better restoration of radiographic features, including SL and improvements in clinical outcomes, compared with static cages in propensity-matched cohorts in patients undergoing one- or two-level open TLIFs.

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.

Feasibility of the Non-Window-Type 3D-Printed Porous Titanium Cage in Posterior Lumbar Interbody Fusion: A Randomized Controlled Multicenter Trial.

Three-dimensionally printed titanium (3D-Ti) cages can be divided into 2 types: window-type cages, which have a void for bone graft, and non-window-type cages without a void. Few studies have investigated the necessity of a void for bone graft in fusion surgery. Therefore, the present study assessed the clinical and radiographic outcomes of window and non-window-type 3D-Ti cages in single-level posterior lumbar interbody fusion. A total of 70 patients were randomly assigned to receive either a window or non-window cage; 61 patients (87%) completed final follow-up (32 from the window cage group, 29 from the non-window cage group). Radiographic outcomes, including fusion rates, subsidence, and intra-cage osseointegration patterns, were assessed. Intra-cage osseointegration was measured using the intra-cage bridging bone score for the window cage group and the surface osseointegration ratio score for the non-window cage group. Additionally, we looked for the presence of the trabecular bone remodeling (TBR) sign on computed tomography (CT) images. Of the 61 patients, 58 achieved interbody fusion, resulting in a 95.1% fusion rate. The fusion rate in the non-window cage group was comparable to, and not significantly different from, that in the window cage group (96.6% and 93.8%, p > 0.99). The subsidence rate showed no significant difference between the window and non-window cage groups (15.6% and 3.4%, respectively; p = 0.262). The intra-cage osseointegration scores showed a significant difference between the groups (p = 0.007), with the non-window cage group having a higher proportion of cases with a score of 4 compared with the window cage group. The TBR sign was observed in 87.9% of patients who achieved interbody fusion, with a higher rate in the non-window cage group across the entire cohort although the difference was not significant (89.7% versus 78.1%, p = 0.385). Non-window-type 3D-Ti cages showed equivalent clinical outcomes compared with window-type cages and comparable interbody fusion rates. These results suggest that the potential advantages of 3D-Ti cages could be optimized in the absence of a void for bone graft by providing a larger contact surface for osseointegration. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

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.

Quantitative Threshold of Intraoperative Radiological Parameters for Suspecting Oblique Lumbar Interbody Fusion Cage Malposition Triggering Contralateral Radiculopathy.

This study aimed to clarify the quantitative threshold of intraoperative radiological parameters for suspecting posterior malposition of the oblique lumbar interbody fusion (OLIF) cage triggering contralateral radiculopathy. We measured the sagittal center and axial rotation angle (ARA) of the cage using postoperative computed tomography (CT) in 130 patients (215 cages) who underwent OLIF. The location of the cage tip was determined from axial magnetic resonance imaging in selected cases based on CT simulations to assess whether the cage was in contact with the contralateral exiting nerve or whether the surgical instruments could contact the nerve during intradiscal maneuvers. The sagittal center of the cages was on average 41.5% from the anterior edge of the endplate (shown as AC/AP value: anterior end plate edge-cage center/anterior-posterior endplate edge ×100%), and posterior cage positioning ≥50% occurred in 14% of the cages. The ARA was -2.9°, and posterior oblique rotation of the cages ≥10° (ARA ≤ -10°) was observed in 13%. CT simulation showed that the cage tip could directly contact the contralateral nerve when the cage was placed deep in the posterior portion ≥50% of the AC/AP values with concomitant posterior axial rotation ≥10° (ARA ≤ -10°), or deep in an extremely rare portion ≥60% of the AC/AP values with posterior axial rotation ≥0° (ARA ≤ 0°). Six percent of the cages (13/215) were placed in these posterior oblique areas (potential contact area: PCA). Three cages in the PCA were in direct contact with the contralateral nerves, and 9 were placed deep just anterior to the nerves. Symptomatic contralateral radiculopathy occurred in 2 cages (2/13/215, 15.3%/0.9%). Two intraoperative radiological parameters (AC/AP and ARA) measurable during OLIF procedures may become practical indicators for suspecting cage malposition in PCA and may be available when determining whether to consider cage revision intraoperatively to a more ventral disc space or anteriorly from the opposite endplate edge.

A novel Mg-Zn-Nd-Zr alloy lumbar interbody fusion cage: An in vitro and in vivo study

Interbody fusion is recognized as the golden standard of surgical intervention for degenerative disc disease (DDD). Interbody fusion cage made of polyetheretherketone (PEEK) is commonly used in lumbar interbody fusion surgery in the treatment of DDD worldwide. However, there are some limitations of PEEK including their bio-inert nature and impediment to host bone integration. This study aimed to evaluate the degradation profile and osteoinductive potential of biodegradable Mg-Zn-Nd-Zr cages with/without micro-arc oxidation (MAO) coatings. The Mg-Zn-Nd-Zr alloy cages, whether coated with MAO or not, demonstrated commendable biocompatibility and biomechanical properties. Immersion and electrochemical tests show better corrosion resistance of MAO coatings in vitro. mRNA sequencing, RT-qPCR and Western blotting revealed that Mg-Zn-Nd-Zr and Mg-Zn-Nd-Zr/MAO had a better effectiveness on osteoinductivity. In vivo evaluations in ovine models over 12 weeks and 24 weeks post-implantation revealed radiological and histological evidence of enhanced bone formation adjacent to the Mg-Zn-Nd-Zr alloy cages compared to PEEK counterparts. Moreover, the MAO-coated cages exhibited a reduced propensity for gas formation. The Mg-Zn-Nd-Zr alloy is as a superior osteoinductive material compared with PEEK, with the MAO coating offering an advantage in mitigating gas production. Nonetheless, further research is warranted to refine the alloy's composition or surface treatments, particularly to address the challenges associated with rapid gas evolution during the early post-implantation period.

Expandable Cages for Lumbar Interbody Fusion: A Narrative Review.

Lumbar fusion surgery for treating degenerative spinal diseases has undergone significant advancements in recent years. In addition to posterior instrumentation, anterior interbody fusion techniques have been developed along with various cages for interbody fusion. Recently, expandable cages capable of altering height, lordotic angle, and footprint within the disc space have garnered significant attention. In this manuscript, we review the current status, clinical outcomes, and future prospects of expandable cages for lumbar interbody fusion based on the existing literature. Expandable cages are suitable for minimally invasive spinal surgeries. Small-sized cages can be inserted and subsequently expanded to a larger size within the disc space. While expandable cages generally demonstrate superior clinical outcomes compared to static cages, some studies have suggested comparable or even poorer outcomes with expandable cages than static cages. Careful interpretation through additional long-term follow-ups is required to assess the utility of expandable cages. If these shortcomings are addressed and the advantages are further developed, expandable cages could become suitable surgical instruments for minimally invasive spinal surgeries.

Do expandable cage size and number of cages matter in transforaminal lumbar interbody fusion at L5-S1? A comparative biomechanical analysis using finite element modeling.

Expandable transforaminal lumbar interbody fusion (TLIF) cages were designed to address the limitations of static cages. Bilateral cage insertion can potentially enhance stability, fusion rates, and segmental lordosis. However, the benefits of unilateral versus bilateral expandable cages with varying sizes in TLIF remain unclear. This study used a validated finite element spine model to compare the biomechanical properties of L5-S1 TLIF by using differently sized expandable cages inserted unilaterally or bilaterally. A finite element model of X-PAC expandable lumbar cages was created and used at the L5-S1 level. This model had cage dimensions of 9 mm in height, 15° in lordosis, and varying widths and lengths. Various placements (unilateral vs bilateral) and sizes were examined under pure moment loading to evaluate range of motion, adjacent-segment motion, and endplate stress. Stability at the L5-S1 level decreased when smaller cages were used in both the unilateral and bilateral cage models. In the unilateral model, cage 1 (the smallest cage) resulted in 47.9% more motion at the L5-S1 level compared to cage 5 (the largest cage) in flexion, as well as 64.8% more motion in extension. Similarly, in the bilateral TLIF model, bilateral cage 1 led to 49.4% more motion at the L5-S1 level in flexion and 73.4% more motion in extension compared to bilateral cage 5. Unilateral insertion of cage 5 provided superior stability in flexion and surpassed cages 1-3 in extension when compared to cages inserted either unilaterally or bilaterally. Reduced motion at L5-S1 correlated with increased adjacent-segment motion at L4-5. Bilateral TLIF resulted in greater adjacent-segment motion compared to unilateral TLIF with the same-size cages. Inferior endplates experienced higher stress during flexion and extension than superior endplates, with this difference being more pronounced in the bilateral model. In bilateral cage placement, stress differences ranged from 46.3% to 60.0%, while they ranged from 1.1% to 9.6% in unilateral cages. Qualitative analysis revealed increased focal stress in unilateral cages versus bilateral cages. The authors' study shows that using a large unilateral TLIF cage may offer better stability than the bilateral insertion of smaller cages. While large bilateral cages increase adjacent-segment motion, they also provide a uniform stress distribution on the endplates. These findings deepen our understanding of the biomechanics of the available expandable TLIF cages.

Biportal endoscopic transforaminal lumbar interbody fusion using a large cage for degenerative spondylolisthesis with stenosis.

Recently, biportal endoscopic transforaminal lumbar interbody fusion (TLIF) has been used to treat lumbar degenerative diseases, such as lumbar instability and spondylolisthesis. Biportal endoscopic TLIF may have the advantages of endoscopic spine approaches and minimally invasive lumbar fusion surgeries. In this biportal endoscopic TLIF, large cages similar to oblique lumbar interbody fusion (OLIF) cages have been used. Biportal endoscopic TLIF using a large cage can be successfully performed in the lower lumbar area. The author presents the surgical technique of biportal endoscopic TLIF using a large cage. The video can be found here: https://stream.cadmore.media/r10.3171/2024.1.FOCVID23231.

Pressure Dynamics on Intervertebral Disc Cages in Transforaminal Lumbar Interbody Fusion: A Cadaver Study

This study aimed to quantify the change in pressure on the cage during compression manipulation in lumbar interbody fusion. While the procedure involves applying compression between pedicle screws to press the cage against the endplate, the exact compression force remains elusive. We hypothesize that an intact facet joint might serve as a fulcrum, potentially reducing cage pressure. Pressure on the intervertebral disc cage was measured during compression manipulation in 4 donor cadavers undergoing lumbar interbody fusion. Unilateral facetectomy models with both normal and parallel compression and bilateral facetectomy models were included. A transforaminal lumbar interbody fusion cage with a built-in load cell measured the compression force. Pressure data from 14 discs indicated a consistent precompression pressure average of 68.16N. Following compression, pressures increased to 125.99N and 140.84N for normal and parallel compression postunilateral facetectomy, respectively, and to 154.58N and 150.46N for bilateral models. A strong linear correlation (correlation coefficient: 0.967, P<0.0001) between precompression and postcompression pressures emphasized the necessity of sufficient precompression pressure for achieving desired postcompression outcomes. None of the data showed a decrease in compression force to the cage with the compression maneuver. Both normal and parallel compression maneuvers effectively increased the pressure on the cage, irrespective of the facet joint resection status. Compression manipulation consistently enhanced compressive force on the cage. However, when baseline pressure is low, the manipulation might not yield significant increases in compression force. This underlines the essential role of meticulous precompression preparation in enhancing surgical outcomes.

Characterization of additively manufactured lumbar interbody fusion cages based on triply periodic minimal surfaces

The advent of laser powder bed fusion (LPBF) allows the fabrication of open-porous bone implants such as lumbar interbody fusion (LIF) cages. However, common LIF cages feature massive support structures and cavities for bone substitute material to meet regulatory requirements with respect to mechanical and biological properties. Since the use of autologous bone substitutes involves significant costs and risks, research is being conducted into alternative designs. This is where the present study comes in by exploring the potential of triply periodic minimal surfaces (TPMS) for metallic LIF cages without supports and cavities in a holistic approach. Specifically, various homogeneous and graded scaffolds with pore size of 400–1100μm and volume fraction of ≤0.25 are designed before being produced from Ti-6Al-4V ELI powder using LPBF. Morphological characterization demonstrates a high process fidelity with a maximum of 8.7% target/actual deviation for the volume fraction. This promotes structural integrity so that the compressive strength of 69MPa or 20.6kN complies with the minimum requirements of ASTM F2077. Based on in vitro cell tests, a mineralization process including bone matrix formation is observed in all variants, with the homogeneous scaffold with 1100μm pore size proving to be particularly beneficial. In conclusion, the results encourage the further development of TPMS based LIF cages without support structures and cavities.

Comparing Outcomes of Banana-Shaped and Straight Cages in Transforaminal Lumbar Interbody Fusion for Lumbar Degenerative Diseases: A Systematic Review and Meta-Analysis.

This meta-analysis aims to refine the understanding of the optimal choice between different cage shapes in transforaminal lumbar interbody fusion (TLIF) by systematically comparing perioperative data, radiological outcomes, clinical results, and complications associated with banana-shaped and straight bullet cages. A meticulous literature search encompassing PubMed, Embase, Scopus, Web of Science, China Knowledge Network, and Wanfang Data was executed up to October 5, 2023. Inclusion criteria focused on studies comparing banana-shaped and straight bullet cages in TLIF. The quality of included studies was assessed using appropriate tools such as the Newcastle-Ottawa Scale (NOS) for nonrandomized studies. Rigorous evaluations were performed for radiographic outcomes, including disc height (DH), segmental lordosis (SL), lumbar lordosis (LL), subsidence, and fusion rates. Clinical outcomes were meticulously evaluated using visual analogue scale (VAS), Oswestry Disability Index (ODI), and complications. The analysis incorporated 7 studies, involving 573 patients (297 with banana-shaped cages, 276 with straight cages), all with NOS ratings exceeding 5 stars. No statistically significant differences were observed in operative time, blood loss, or hospitalization between the 2 cage shapes. Banana-shaped cages exhibited greater changes in DH (p = 0.001), SL (p = 0.02), and LL (p = 0.01). Despite statistically higher changes in ODI for straight cages (26.33, p < 0.0001), the actual value remained similar to banana-shaped cages (26.15). Both cage types demonstrated similar efficacy in VAS, complication rates, subsidence, and fusion rates. Although banana-shaped cages can excel in restoring DH, SL, and LL, straight bullet cages can provide comparable functional improvements, pain relief, and complication rates.

Comparative Biomechanical Evaluation of Unilateral and Bilateral Cages in Posterior Lumbar Interbody Fusion: Endplates Subsidence, Pedicle Screw Loosening and Implant Stability

Implant sinking, pedicle screw loosening, and instability are commonly observed complications in posterior lumbar interbody fusion (PLIF) surgeries, attributed to a range of mechanical, biomechanical, and environmental factors. To address these challenges, the utilization of unilateral cages positioned obliquely, along with bilateral posterior instrumentation, and employing a material with a comparable modulus to cortical bone, has shown promising efficacy. The present study employed image-based finite element analysis (FEA) to evaluate the influences on cage sinking, screw loosening, and construct stability. The outcomes revealed that obliquely positioned unilateral fusion cage constructs with posterior instrumentation yielded superior biomechanical outcomes, characterized by reduced range of motion and stress distortion at the cage-endplate and screw-bone junctions. Furthermore, these findings indicated a lower risk of fractures and diminished deformations in normal and traumatic events. Hence, the utilization of biocompatible cage materials and structural symmetry holds critical significance for achieving biomechanical success in PLIF surgery.

Lumbosacral Traumatic Spondylolisthesis L5 to S1-Classification and Surgical Management of a Difficult Presentation.

Lumbosacral traumatic spondylolisthesis L5-S1 is a rare clinical entity that compromises the stability of the L5 vertebra by displacing it anteriorly, laterally, or posteriorly on the S1 vertebral body secondary to osteotendinous and/or articular compromise of this segment due to trauma. This pathology is difficult to classify and manage; although surgical management remains the gold standard, short- and long-term results in the literature are scarce and highly variable. We present the case of a 53-year-old patient with lumbar trauma due to a free fall from a height of 6 meters. The fall resulted in cauda equina syndrome secondary to lumbosacral traumatic spondylolisthesis L5-S1, which required immediate surgical management. For surgical management, we used a posterior approach for L5-S1 transpedicular screw fixation, spinal decompression, bilateral root foraminotomy of L5, and L5-S1 open transforaminal lumbar interbody fusion with open reduction. After the operation, the patient reported immediate improvement of postoperative lower extremities pain and was discharged on the third postoperative day after achieving clinical improvement with physical therapy and bladder rehabilitation exercises. Lumbosacral traumatic spondylolisthesis L5-S1 is an unusual pathology that requires further study as there is currently no standardized classification. Surgical management is the gold standard and includes open reduction with short transpedicular screw fixation in segment L5-S1 and other surgical interventions such as extension to the pelvis with iliac screws, screws to the L4 vertebral body, and use of lumbar interbody fusion cages.

Comparison between Three-Dimensional Printed Titanium and PEEK Cages for Cervical and Lumbar Interbody Fusion: A Prospective Controlled Trial.

The three-dimensional printing titanium (3DPT) cage with excellent biomechanical properties and osseointegration capabilities has been initially used in spinal fusion, while the polyetheretherketone (PEEK) cage, a bioinert material device, has been a widely used for decades with relatively excellent clinical outcomes. This study was performed to investigate the early radiographic and clinical outcomes of 3DPT cage versus PEEK cage in patients undergoing anterior cervical discectomy and fusion (ACDF) and transforaminal lumbar interbody fusion (TLIF). This prospective controlled trial, from December 2019 to June 2022, included patients undergoing ACDF and TLIF with 3DPT cages and compared them to patients using PEEK cages for treating spinal degenerative disorders. The outcome measures included radiographic parameters (intervertebral height [IH], subsidence, fusion status, and bone-cage interface contact) and clinical outcomes (Japanese Orthopaedic Association [JOA], Neck Disability Index [NDI], Oswestry Disability Index [ODI], Short Form 12-Item Survey [SF-12], Visual Analog Scale [VAS], and Odom's criteria). Student's independent samples t test and Pearson's chi-square test were used to compare the outcome measures between the two groups before surgery and at 1 week, 3 and 6 months after surgery. For the patients undergoing ACDF, the 3DPT (18 patients/[26 segments]) and PEEK groups (18 patients/[26 segments]) had similar fusion rates at 3 months and 6 months follow-up (3 months: 96.2% vs. 83.3%, p = 0.182; 6 months: 100% vs. 91.7%, p = 0.225). The subsidence in the 3DPT group was significantly lower than that in the PEEK group (3 months: 0.4 ± 0.2 mm vs. 0.9 ± 0.7 mm p = 0.004; 6 months: 0.7 ± 0.3 mm vs. 1.5 ± 0.8 mm, p < 0.001). 3DPT and PEEK cage all achieved sufficient contact with the cervical endplates. For the patients undergoing TLIF, the 3DPT (20 patients/[26 segments]) and PEEK groups (20 patients/[24 segments]) had no statistical difference in fusion rate (3 months: 84.6% vs. 58.3%, p = 0.059; 6 months: 92.3% vs. 75%, p = 0.132). The subsidence was lower than that in the PEEK group without significantly difference (3 months: 0.9 ± 0.7 mm vs.1.2 ± 0.9 mm p = 0.136; 6 months: 1.6 ± 1.0 mm vs. 2.0 ± 1.0 mm, p = 0.200). At the 3-month follow-up, the bone-cage interface contact of the 3DPT cage was significantly better than that of the PEEK cage (poor contact: 15.4% vs. 75%, p < 0.001). The values of UAR were higher in the 3DPT group than in the PEEK group during the follow-up in cervical and lumbar fusion, there were more statistical differences in lumbar fusion. There were no significant differences in the clinical assessment between 3DPT or PEEK cage in spinal fusion. The 3DPT cage and PEEK cage can achieve excellent clinical outcomes in cervical and lumbar fusion. The 3DPT cage has advantage in fusion quality, subsidence severity, and bone-cage interface contact than PEEK cage.

Radiographic and Patient-Reported Outcomes in Anteriorly Placed Transforaminal Lumbar Interbody Fusion Cage Versus Anterior Lumbar Interbody Fusion With Posterior Instrumentation.

Retrospective cohort study. To compare outcomes in anteriorly placed transforaminal lumbar interbody fusions (TLIFs) and anterior lumbar interbody fusions (ALIFs). TLIF and ALIF are surgical techniques that have become more prevalent in recent years. Although studies have compared the two, none have considered TLIFs with anteriorly placed cages, which may serve as a better comparison to ALIFs. Patients undergoing TLIF or ALIF with posterior instrumentation from 2010 to 2020 at a tertiary care institution were retrospectively identified. TLIF cage position was assessed and those with anterior placement were included. Electronic medical records were reviewed to identify patient characteristics and patient-reported outcomes. Radiographic outcomes included posterior disc height (DH), lumbar lordosis (LL), sacral slope, pelvic incidence, and pelvic tilt. Statistical analysis was performed to compare the two groups. Of the 351 patients, 108 had ALIF with posterior instrumentation and 207 had a TLIF. Preoperatively, patients undergoing TLIF had less LL (53.7° vs . 60.6°, P < 0.001), sacral slope (38.3° vs . 43.7°, P < 0.001), and pelvic incidence (60.1° vs . 66.1°, P < 0.001), all of which remained significant at 1-year and long-term follow-up ( P < 0.001). The TLIF group had less ∆DH (1.51° vs . 5.43°, P < 0.001), ∆LL (1.8° vs . 2.97°, P = 0.038), and ∆segmental lordosis (0.18° vs . 4.40°, P < 0.001) at 1 year postoperatively. At 2 to 3 years, ∆DH ( P < 0.001) and ∆segmental lordosis ( P = 0.001) remained significant, but ∆LL ( P = 0.695) did not. Patients in the TLIF group had higher Visual Analog Scale-Back scores 1 year postoperatively (3.68 vs . 2.16, P = 0.008) and experienced less improvement in Oswestry Disability Index (-17.1 vs . -28.6, P = 0.012) and Visual Analog Scale-Back (-2.67 vs . -4.50, P = 0.008) compared with patients undergoing ALIF. Our findings suggest that ALIF with posterior instrumentation performed superiorly in radiographic outcomes and patient-reported outcomes compared with anteriorly placed TLIFs. Anteriorly placed TLIF cages may not achieve the same results as those of ALIF cages.

Spinopelvic sagittal realignment and incidence of adjacent segment disease after single-segment posterior lumbar inter-body fusion using 12° lordotic cages-a 2-year prospective cohort study.

The importance of spinopelvic sagittal alignment for adjacent segment disease (ASD) after lumbar fusion surgery has been reported. However, no longitudinal cohort studies have determined the extent to which segmental alignment and spinopelvic global alignment can be achieved using 12° lordotic cages in posterior lumbar inter-body fusion (PLIF) and the extent to which the development of ASD can be prevented. The purpose of this study was to analyze changes in segmental and spinopelvic sagittal alignment after single-segment PLIF with 12° lordotic cages, to clarify the relationship between changes in segmental and spinopelvic sagittal alignment, and to report the incidence of ASD at 2 years postoperatively. Subjects in this 2-year prospective longitudinal cohort study were 28 patients who had undergone L4/5 PLIF using 12° lordotic cages. Incidence of operative ASD (O-ASD) was evaluated as clinical outcomes. Radiological measurements were examined preoperatively and at 3 months, 1 year and 2 years postoperatively. The following radiographic spinopelvic parameters were measured: segmental lordosis (SL) at L4/5; sagittal vertical axis (SVA); T1 pelvic angle (TPA); thoracic kyphosis (TK); lumbar lordosis (LL); sacral slope (SS); pelvic tilt (PT); and pelvic incidence (PI). With respect to radiological outcomes, changes in SL (ΔSL) and spinopelvic parameters and the incidence of radiological ASD (R-ASD) were evaluated. Correlations of ΔSL and changes in other spinopelvic parameters (ΔSVA, ΔTPA, ΔTK, ΔLL, ΔSS, ΔPT, and ΔPI-LL) between preoperatively and 3 months postoperatively were examined. The follow-up rate was 100% (n=28) at 1 year postoperatively and 96.4% (n=27) at 2 years postoperatively. No cases of O-ASD were seen during 2 years of follow-up. Significant realignment was observed and maintained at 2 years postoperatively in almost all spinopelvic sagittal parameters (SL, SVA, TPA, LL, PT, PI-LL). Regarding the correlation between ΔSL and other parameters, significant correlations were detected with ΔSVA (r=-0.37, P<0.05) and ΔLL (r=0.538, P<0.01). Three cases (11.1%) showed R-ASD at 2 years postoperatively. PLIF with 12° lordotic cages for L4 degenerative spondylolisthesis improved SL and global sagittal realignment, and achieved satisfactory clinical outcomes with a low incidence of ASD during 2 years of follow-up.

Anisotropic biomimetic trabecular porous three-dimensional-printed Ti-6Al-4V cage for lumbar interbody fusion

Lumbar fusion is a popular surgical procedure for the treatment of degenerative lumbar disc disease; however, it may be accompanied by complications, such as cage loosening, subsidence, and non-union. This study engineered and fabricated a three-dimensional (3D)-printed anisotropic biomimetic trabecular porous Ti-6Al-4V cage for lumbar interbody fusion. The study evaluated the structural design, manufacturability, mechanical properties, and cellular functions of the fabricated structures compared to currently available interbody cages. In vitro tests assessed the biofunctionality of the 3D-printed porous cage, which revealed anisotropic biomimetic trabecular porous Ti-6Al-4V cages with 65%-85% porosity, and 600 μm pore size. The microscopy analysis of surface properties indicated in situ micro- and nano-roughness. The mechanical properties decreased progressively with increasing porosity, and the optimized frame-reinforced porous cage achieved higher compressive strength and stiffness than the fully porous fusion. The 70% 3D-printed porous frame-reinforced cage had suitable mechanical performance compared with the polyether-ether-ketone (PEEK) cage. The anisotropic biomimetic trabecular porous structures and the surface micro- and nano-roughness modifications achieved excellent biological functions in vitro. In conclusion, our fabricated 70% 3D-printed porous frame-reinforced Ti-6Al-4V cage with anisotropic biomimetic trabeculae is a promising strategy for lumbar interbody fusion.

Expandable versus static cages in unilateral biportal endoscopy lumbar interbody fusion (ULIF) for treating degenerative lumbar spondylolisthesis (DLS): comparison of clinical and radiological results

BackgroundIn recent years, early rehabilitation after spinal fusion and the recovery of physiological curvature have attracted much attention. Therefore, expandable cages have entered the field of vision of scientists. The goal of the current study was to compare the clinical and radiological results of unilateral portal endoscopic lumbar interbody fusion (ULIF) in the treatment of degenerative lumbar spondylolisthesis (DLS) with expandable versus static cages.MethodsWe retrospectively analysed patients who received ULIF treatment for DLS from May 2019 to February 2021. Patients were categorized by cage type (static vs. expandable), and the main study was the preop and postop clinical and radiological index changes of the patients.ResultsEighty-four patients were included (38 in the static cages group; 46 in the expandable cages group). There was no difference in the preop results between the two groups. The VAS scores for low back and leg pain and ODI scores in the expandable cages group 7 d postop were significantly superior to those in the static cages group (P < 0.05), and the segmental angle and PDH in the expandable cages group postop were significantly higher than those in the static cages group (P < 0.05). The fusions at 6 m postop in the expandable cages group were superior to those in the Static Cages group (P < 0.05).ConclusionsThe results of this study showed that compared with the stable cage group, the expandable cage group had unique advantages in restoring the physiological curvature of the lumbar spine, increasing the fusion rate, and relieving pain in the early postoperative period. ULIF can be used to treat single-segment, mild lumbar spondylolisthesis patients using expandable cages instead of static cages.