Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Expandable Cages: Increased Risk of Late Postoperative Subsidence Without a Real Improvement of Perioperative Outcomes: A Clinical Monocentric Study

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

STUDY DESIGN

Retrospective Case-Series.

OBJECTIVES

Due to heterogeneity in previous studies, the effect of MI-TLIF on postoperative segmental lordosis (SL) and lumbar lordosis (LL) remains unclear. Therefore, we aim to identify radiographic factors associated with lordosis after surgery in a homogenous series of MI-TLIF patients.

METHODS

A single-center retrospective review identified consecutive patients who underwent single-level MI-TLIF for grade 1 degenerative spondylolisthesis from 2015-2020. All surgeries underwent unilateral facetectomies and a contralateral facet release with expandable interbody cages. PROs included the ODI and NRS-BP for low-back pain. Radiographic measures included SL, disc height, percent spondylolisthesis, cage positioning, LL, PI-LL mismatch, sacral-slope, and pelvic-tilt. Surgeries were considered "lordosing" if the change in postoperative SL was ≥ +4° and "kyphosing" if ≤ -4°. Predictors of change in SL/LL were evaluated using Pearson's correlation and multivariable regression.

RESULTS

A total of 73 patients with an average follow-up of 22.5 (range 12-61) months were included. Patients experienced significant improvements in ODI (29% ± 22% improvement, P < .001) and NRS-BP (3.3 ± 3 point improvement, P < .001). There was a significant increase in mean SL (Δ3.43° ± 4.37°, P < .001) while LL (Δ0.17° ± 6.98°, P > .05) remained stable. Thirty-eight (52%) patients experienced lordosing MI-TLIFs, compared to 4 (5%) kyphosing and 31 (43%) neutral MI-TLIFs. A lower preoperative SL and more anterior cage placement were associated with the greatest improvement in SL (β = -.45° P = .001, β = 15.06° P < .001, respectively).

CONCLUSIONS

In our series, the majority of patients experienced lordosing or neutral MI-TLIFs (n = 69, 95%). Preoperative radiographic alignment and anterior cage placement were significantly associated with target SL following MI-TLIF.

Definition of cage subsidence in transforaminal lumbar interbody fusion (TLIF) approach and posterior lumbar interbody fusion (PLIF) approach - A systematic review

BACKGROUND

Although cage subsidence is one of the most common phenomenona associated with interbody fusions and was characterized more than 70 years ago, a standardized method for its measurement, detection, and reporting among different lumbar fusion procedures does not exist. Here, we review previously published literature on cage subsidence to present the most common methods for defining subsidence in the posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) techniques.

METHODS

A search was completed in PubMed and Embase with inclusion criteria focused on identifying any study that provided descriptions of the method, imaging modality, and subsidence threshold used to define the presence of cage subsidence in study articles published between January 1, 2001 and December 31, 2022.

RESULTS

A total of 54 studies were included in the final analysis. Among them, 32 (59.2 %) reported on TLIF, 20 (37.1 %) reported on PLIF, and 2 studies (3.7 %) reported on both approaches. For TLIF and PLIF procedures, the preferred method to determine subsidence was cage migration into the vertebral bodies rather than changes in disc height. In the TLIF group, the predominant criteria for defining subsidence were thresholds of ≥ 2 mm and > 2 mm utilized in each of 10 of the 34 studies (58.8 %). Similarly, in the PLIF group, the common criterion for defining subsidence was also ≥ 2 mm, observed in 5 of 22 studies (22.7 %), with > 2 mm observed in 4 studies (18.2 %). The methods for assessing cage migration or disc height change varied substantially among studies, with none of the measurements being consistently applied in more than 50 % of the studies.

CONCLUSIONS

Inconsistency persists in the methods used to determine, report, or measure the degree of subsidence. Surgeons and researchers should standardize these methods to ensure consistency and generalizability in reporting and studying subsidence.

Failure of an expandable lumbar interbody spacer - a critical analysis of secondary collapse, pseudoarthrosis and revision rates after thoracolumbar fusion

PURPOSE

To report on the failure rates of an expandable interbody spacer, used for spinal instrumented transforaminal lumbar interbody fusion (TLIF) or posterior thoracolumbar interbody fusion (PLIF).

METHODS

In this retrospective, single-center observational cohort study we reviewed consecutive PLIF/TLIF patients using the Catalyft™ PL and PL40 expandable titanium interbody implant (Medtronic, Minneapolis (USA)) between 07/2022 and 11/2023. We recorded patient demographics, surgical parameters, adverse events, radiological parameters and clinical outcomes according to the MacNab criteria.

RESULTS

We identified 53 patients (mean age 68.6 ± 11.5 years; 49.1% female; mean BMI 25.7 ± 4.4 kg/m2), in which 92 Catalyft™ spacers were implanted, mostly at L4/5 (n = 35; 38.0%) and L5/S1 (n = 31; 33.7%) for degenerative (n = 44; 83.0%), deformity (n = 7; 13.2%) or other indications (n = 2; 3.8%). We noticed secondary collapse of 20 (21.7%) spacers in 11 patients (20.7%) occurring after a mean time of 4.0 ± 4.1 months postoperatively. Age < 70 years was identified as risk factor for secondary collapse (OR 3.71, 95% CI 1.31-10.5, p = 0.014), but no association was found regarding other patient-specific or surgery-related variables. Pseudarthrosis was evident in seven patients (13.2%), of which four (7.6%) required revision surgery. Clinical outcome at last follow-up (mean 6.4 ± 4.2 months) was excellent/good in 29 (54.7%), fair in 14 (26.4%) and poor in six patients (11.3%).

CONCLUSION

We provide a critical analysis of our series of patients with use of a specific type of expandable interbody spacer. We noticed failure and secondary collapse in an unacceptably high number of implants, some of which required revision surgery.

Bone Density Correlates With Depth of Subsidence After Expandable Interbody Cage Placement: A Biomechanical Analysis

STUDY DESIGN

Biomechanical analysis.

OBJECTIVE

To evaluate the depth of subsidence resulting from an expandable interbody cage at varying bone foam densities.

SUMMARY OF BACKGROUND DATA

Expandable interbody cages have been shown to be associated with increased rates of subsidence. It is critical to evaluate all variables which may influence a patient's risk of subsidence following the placement of an expandable interbody cage.

METHODS

In the first stage of the study, subsidence depth was measured with 1 Nm of input expansion torque. In the second stage, the depth of subsidence was measured following 150 N output force exerted by an expandable interbody cage. Within each stage, different bone foam densities were analyzed, including 5, 10, 15, and 20 pounds per cubic foot (PCF). Five experimental trials were performed for each PCF material, and the mean subsidence depths were calculated. Trials which failed to reach 150 N output force were considered outliers and were excluded from the analysis.

RESULTS

There was an overall decrease in subsidence depth with increasing bone foam density. The mean subsidence depths at 150 N output force were 2.0±0.3 mm for 5 PCF, 1.8±0.2 mm for 10 PCF, 1.1±0.2 mm for 15 PCF, and 1.1±0.2 mm for 20 PCF bone foam. The mean subsidence depths at 1 Nm of input torque were 2.3±0.5 mm for 5 PCF, 2.3±0.5 mm for 10 PCF, 1.2±0.2 mm for 15 PCF, and 1.1±0.1 mm for 20 PCF bone foam.

CONCLUSIONS

Depth of subsidence was negatively correlated with bone foam density at both constant input torque and constant endplate force. Because tactile feedback of cage expansion into the subsiding bone cannot be reliably distinguished from true expansion of disc space height, surgeons should take bone quality into account when deploying expandable cages.

Intradiscal Osteotomy and Bilateral Expandable Transforaminal Interbody Fusion Cages for Iatrogenic Kyphotic Deformity: A Technical Report

Objectives  Expandable transforaminal interbody fusion (TLIF) devices have been developed to introduce more segmental lordosis through a narrow operative corridor, but there are concerns about the degree of achievable correction with a small graft footprint. In this report, we describe the technical nuances associated with placing bilateral expandable cages for correction of iatrogenic deformity. Materials and Methods  A 60-year-old female with symptomatic global sagittal malalignment and a severe lumbar kyphotic deformity after five prior lumbar surgeries presented to our institution. We performed multilevel posterior column osteotomies, a L3-4 intradiscal osteotomy, and placed bilateral lordotic expandable TLIF cages at the level of maximum segmental kyphosis. Results  We achieve a 21-degree correction of the patient's focal kyphotic deformity and restoration of the patient global sagittal alignment. Conclusion  This case demonstrates both the feasibility and utility of placing bilateral expandable TLIF cages at a single disc space in the setting of severe focal sagittal malalignment. This technique expands the implant footprint and, when coupled with an intradiscal osteotomy, allows for a significant restoration of segmental lordosis.

Short-Term Clinical and Radiographic Evaluation of Patients Treated With Expandable and Static Interbody Spacers Following Lumbar Lateral Interbody Fusion

OBJECTIVE

The goal of this study was to evaluate, using computed tomography (CT) and magnetic resonance imaging (MRI), patients who underwent oblique lateral interbody fusion (OLIF) using either expandable or static interbody spacers.

METHODS

Thirty-five patients with degenerative disc disease were surgically treated with one-level OLIF and were followed up for more than 6 months. The Static group consisted of 22 patients, and 13 patients were in the Expandable group. Intraoperative findings included operative time (min), blood loss (ml), and cage size. Low back pain, leg pain, and leg numbness were measured using the Japanese Orthopedic Association score, visual analogue score, and the Roland-Morris Disability Questionnaire. Radiologic evaluation using computed tomography (CT) and magnetic resonance imaging (MRI) allowed measurement of cage subsidence, cross-sectional area (CSA) of the dural sac, disc height, segmental lordosis, foraminal height, and foraminal CSA preoperatively and 6 months postoperatively.

RESULTS

The Expandable group had significantly larger cage height and lordosis than the Static group (P < 0.05). The Expandable group also had greater dural sac area expansion and enlargement of the intervertebral foramen, as well as better correction of vertebral body slip (P < 0.05). Cage subsidence was significantly lower in the Expandable group (P < 0.05). JOA and VAS scores for leg numbness were significantly better in the Expandable group (P < 0.05).

CONCLUSIONS

Compared with static spacers, expandable spacers significantly enlarged the dural sac area, corrected vertebral body slippage, expanded the intervertebral foramen, and achieved good indirect decompression while reducing cage subsidence, resulting in improvement in clinical symptoms.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

Pressure data from 14 discs indicated a consistent precompression pressure average of 68.16 N. Following compression, pressures increased to 125.99 N and 140.84 N for normal and parallel compression postunilateral facetectomy, respectively, and to 154.58 N and 150.46 N 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.

CONCLUSIONS

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.

Influence of Placement of Lumbar Interbody Cage on Subsidence Risk: Biomechanical Study

OBJECTIVE

Lumbar spinal fusion is a common surgical procedure that can be done with a variety of different instrumentation and techniques. Despite numerous research studies investigating subsidence risk factors, the impact of cage placement on subsidence is not fully elucidated. This study aims to determine whether placement of an expandable transforaminal lumbar interbody fusion cage at the center end plate or at the anterior apophyseal ring affects cage subsidence.

METHODS

A transforaminal lumbar interbody fusion cage was placed centrally or peripherally between 2 synthetic vertebral models of L3 and L4. A compression plate attached to a 10 KN load cell was used to uniaxially compress the assembly. The ultimate force required for the assembly to fail and subsidence stiffness were analyzed. Computed tomography scans of each L3 and L4 were obtained, and maximum end plate subsidence was measured in the frontal plane.

RESULTS

Anterior apophyseal cage placement resulted in higher stiffness of the vertebrae-cage assembly (Ks, 962.89 N/mm) and a higher subsidence stiffness (Kb,987.21 N/mm) compared with central placement (P < 0.05). Ultimate compressive load of the vertebrae-cage assembly did not increase. Moreover, the maximum subsidence depth did not significantly vary between placements.

CONCLUSIONS

The subsidence stiffness increased with anterior apophyseal cage placement. Periphery end plate cortical bone architecture may play a role in resisting the impact of cage subsidence. To fully understand the effect of cage placement on cage subsidence, future studies should investigate its implications on native and diseased spine.

Exploring the differences in radiologic and clinical outcomes of transforaminal lumbar interbody fusion with single- and bi-planar expandable cages: a systematic review and meta-analysis

Transforaminal lumbar interbody fusion (TLIF) is a universal surgical technique used to achieve lumbar fusion. Traditionally static cages have been used to restore the disc space after discectomy. However, newer technological advancements have brought up uniplanar expandable cages (UECs) and more recently bi-planar expandable cages (BECs), the latter with the hope of reducing the events of intra- or postoperative subsidence compared to UECs. However, since BECs are relatively new, there has been no comparison to UECs. In this PRISMA-compliant systematic review, we sought to identify all Medline and Embase reports that used UECs and/or BECs for TLIF or posterior lumbar interbody fusion. Primary outcomes included subsidence and fusion rates. Secondary outcomes included VAS back pain score, VAS leg pain score, ODI, and other complications. A meta-analysis of proportions was the main method used to evaluate the extracted data. Bias was assessed using the ROBINS-I tool. A total of 15 studies were pooled in the analysis, 3 of which described BECs. There were no studies directly comparing the UECs to BECs. A statistically significant difference in fusion rates was found between UECs and BECs (p = 0.04). Due to lack of direct comparative literature, definitive conclusions cannot be made about differences between UECs and BECs. The analysis showed a statistically higher fusion rate for BECs versus UECs, but this should be interpreted cautiously. No other statistically significant differences were found. As more direct comparative studies emerge, future meta-analyses may clarify potential differences between these cage types.

Comparison of surgical outcomes between lumbar interbody fusions using expandable and static cages: a systematic review and meta-analysis

BACKGROUND

The use of static cages for lumbar interbody fusion (LIF) can cause complications such as end plate violation, graft subsidence, and nerve injury. Therefore, expandable cages that allow for in-situ expansion have been developed to overcome these problems. However, it remains uncertain whether expandable cages have better surgical outcomes than static cages do.

PURPOSE

We aimed to determine the effectiveness of expandable cages by analyzing studies that compared the surgical outcomes between the use of expandable cages and static cages.

STUDY DESIGN

A systematic review and meta-analysis.

METHODS

The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to conduct this meta-analysis and systematic review. The primary outcomes of this study were anterior disc height, posterior disc height, segmental lordosis (SL), lumbar lordosis (LL), subsidence rate, numeric rating scale (NRS) scores for back and leg pain, and Oswestry Disability Index (ODI).

RESULTS

Thirteen studies with 1,700 patients were included in the meta-analysis. Compared with static cages for LIFs, expandable cages significantly increased the anterior disc height (standardized mean difference 0.478, 95% confidence interval [CI] 0.088-0.867, p=.0162) and segmental lordosis (sMD 0.307, 95% CI 0.159-0.454, p<.0001). There were no significant differences in the posterior disc height, lumbar lordosis, subsidence rate, back pain, leg pain, or ODI between the two groups.

CONCLUSION

Expandable cages show no clear clinical benefit over static cages.

Early Radiological Assessment of Static and Expandable Cages in Lateral Single Position for Indirect Decompression- Lateral Lumbar Interbody Fusion

OBJECTIVE

This study aimed to compare the postoperative alignment of static and expandable cages in lateral single-position (LSP) for indirect decompression in lateral lumbar interbody fusion (LLIF).

METHODS

We included sixty-seven patients who underwent LSP-LLIF for lumbar degenerative disease. We performed radiological assessments preoperatively and two weeks postoperatively using computed tomography and magnetic resonance imaging. We divided the patients into the expandable cage group (23 patients) and the static cage group (44 patients). We measured disc height (DH), segmental lordosis (SL), and foraminal area (FA) from computed tomography images and the area of the dural sac from magnetic resonance imaging. We recorded surgical outcomes and complications.

RESULTS

Both static and expandable cages demonstrated improvements in DH, SL, FA, and dural sac expansion. However, we found no statistically significant differences in the average change in DH (4.4 ± 2.1 mm vs. 4.2 ± 1.8 mm, P = 0.685), the average change in SL (1.0 ± 4.4° vs. 1.9 ± 3.6°, P = 0.310), or FA change (32.5 ± 31.7 mm2 vs. 34.9 ± 29.5 mm2, P = 0.966) between the expandable and static cage groups. We also found no statistically significant difference in dural sac enlargement between the two groups. We observed no significant differences in operation time, estimated blood loss, or length of hospital stay between the two groups. No severe adverse events or additional surgeries were reported.

CONCLUSIONS

In LSP-LLIF without facet joint resection or other posterior techniques, static and expandable cages showed comparable effectiveness in achieving increased DH, SL, FA, and indirect decompression.

Utilization of Dual Expandable Cages in Lateral Lumbar Interbody Fusion Surgery

The aim of this study is to present a case series of adult patients with lumbar degenerative scoliosis who underwent focused minimally invasive spine (MIS) surgery utilizing a new dual expandable cage technology. The study investigates the effectiveness of this approach in reducing the symptoms and progression of lumbar degenerative scoliosis (LDS). Adult patients with lumbar degenerative scoliosis were selected for focused MIS using the newly introduced expandable cage technology. Patient demographics, preoperative evaluations, surgical details, and postoperative outcomes were recorded. The primary outcome measures included the restoration of disc space height, an improvement in clinical outcomes, and a reduction in surgical complications. Analysis of the case series reveals promising outcomes following focused MIS with the utilization of the new expandable cage technology. The technique demonstrated successful restoration of intervertebral disc space heights and improved clinical outcomes in patients with lumbar degenerative scoliosis. Furthermore, a notable reduction in surgical complications was observed. The findings from this case series suggest that MIS with the implementation of the new expandable cage technology holds promise for patients with lumbar degenerative scoliosis. This approach appears to have the potential to effectively restore disc space heights, improve clinical outcomes, and minimize surgical complications. Here, we want to emphasize and add details to the improved clinical outcomes of this technology; however, further research and larger prospective studies are warranted to validate these preliminary results and establish the long-term benefits and safety profile of this innovative technique.

Relationship between lumbar lordosis, pelvic parameters, PI-LL mismatch and outcome after short fusion surgery for lumbar degenerative disease. Literature review, rational and presentation of public study protocol: RELApSE study (registry for evaluation of lumbar artrodesis sagittal alignEment)

Background

Vertebral arthrodesis for degenerative pathology of the lumbar spine still remains burdened by clinical problems with significant negative results. The introduction of the sagittal balance assessment with the evaluation of the meaning of pelvic parameters and spinopelvic (PI-LL) mismatch offered new evaluation criteria for this widespread pathology, but there is a lack of consistent evidence on long-term outcome.

Methods

The authors performed an extensive systematic review of literature, with the aim to identify all potentially relevant studies about the role and usefulness of the restoration or the assessment of Sagittal balance in lumbar degenerative disease. They present the study protocol RELApSE (NCT05448092 ID) and discuss the rationale through a comprehensive literature review.

Results

From the 237 papers on this topic, a total of 176 articles were selected in this review. The analysis of these literature data shows sparse and variable evidence. There are no observations or guidelines about the value of lordosis restoration or PI-LL mismatch. Most of the works in the literature are retrospective, monocentric, based on small populations, and often address the topic evaluation partially.

Conclusions

The RELApSE study is based on the possibility of comparing a heterogeneous population by pathology and different surgical technical options on some homogeneous clinical and anatomic-radiological measures aiming to understanding the value that global lumbar and segmental lordosis, distribution of lordosis, pelvic tilt, and PI-LL mismatch may have on clinical outcome in lumbar degenerative pathology and on the occurrence of adjacent segment disease.

The Use of Dual Direction Expandable Titanium Cage With Biportal Endoscopic Transforaminal Lumbar Interbody Fusion: A Technical Consideration With Preliminary Results

Objective: Expandable cage technology has emerged for lumbar interbody fusion to restore intervertebral disc space height and alignment through a narrow surgical corridor. The purpose of this study is to present the technique of biportal endoscopic transforaminal lumbar interbody fusion (TLIF) using dual direction expandable cage and provide early clinical results.Methods: We performed the biportal endoscopic TLIF using a dual direction expandable titanium cage for height restoration and a larger footprint in 10 patients. Clinical parameters including Oswestry Disability Index (ODI), visual analogue scale (VAS), and complications were retrospectively analyzed. Also, we investigated radiologic parameters using preoperative and postoperative x-ray images.Results: We successfully inserted dual direction expandable cages during biportal endoscopic TLIF. There was no significant subsidence or collapse of the expandable cages during the 6-month follow-up period. Lumbar lordosis and disc height were significantly increased after surgery. ODI and VAS scores were significantly improved at 6 months after surgery.Conclusion: In this report, we describe the first use of a dual direction expandable interbody TLIF cage that expands in both width and height in biportal endoscopic TLIF surgery. Early clinical and radiographic outcomes of this TLIF technique may be favorable in early 6-month follow-up.

Association of spinopelvic index with proximal junctional failure developing in adult spinal deformity after surgical treatment: an observational study

BACKGROUND

Those pelvic parameters of sacral slope (SS) and pelvic tilt (PT) correlated significantly to lumbar spine and hip joints respectively. We proposed the match between SS and PT, namely spinopelvic index (SPI), in order to investigate whether the SPI correlated to proximal junctional failure (PJF) in adult spinal deformity (ASD) after correction surgery.

METHODS

Ninety-nine ASD patients who had undergone long-fusion (≥ 5 vertebras) surgeries were reviewed retrospectively in two medical institutions from January 2018 to December 2019. Those SPI were calculated with the equation: SPI = SS/PT, and analyzed using the receiver operating characteristic curve (ROC) analysis. All participants were subdivided into the observational and control group. Comparisons of demographics, surgical and radiographic data between the two groups were performed. A Kaplan-Meier curve and log-rank test was used to analyze the differences in PJF-free survival time, and the 95% confidence intervals (CI) were recorded respectively.

RESULTS

Nineteen patients suffering from PJF had much smaller postoperative SPI (P = 0.015), but much larger TK postoperatively (P < 0.001). ROC analysis determined the best cutoff value of 0.82 for SPI (sensitivity = 88.5%, specificity = 57.9%; AUC = 0.719, 95%CI: 0.612-0.864; P = 0.003). There were 19 and 80 cases in the observational (SPI ≤ 0.82) and control group (SPI > 0.82) respectively. The incidence of PJF in the observational group was much higher (11/19 VS 8/80, P < 0.001); further logistic regression analysis showed that SPI ≤ 0.82 was associated with increased odds of PJF (odds ratio: 12.375; 95%CI: 3.851-39.771). PJF-free survival time in the observational group decreased significantly (P < 0.001, log-rank test), moreover, multivariate analysis demonstrated that a value of SPI ≤ 0.82 (HR 6.626, 95%CI: 1.981-12.165) was significantly associated with PJF.

CONCLUSIONS

For ASD patients underwent long-fusion surgeries, the SPI should be over 0.82. The incidence of PJF may increase by 12-fold in such individuals with the immediate SPI ≤ 0.82 postoperatively.

Extreme Lateral Interbody Fusion (XLIF) with Lateral Modular Plate Fixation: Preliminary Report on Clinical and Radiological Outcomes

The lateral transpsoas approach (extreme lateral interbody fusion, or XLIF) allows surgeons to use various lordotic cage sizes to help restore intervertebral disk height, correct sagittal alignment, and improve fusion rates. The use of standalone devices has consistently raised doubts due to the high risk of complications and inadequate functional recovery that a circumferential arthrodesis can support. The recent introduction of a novel XLIF cage with adapted lateral plate fixation (XLPF) may further enhance the structural rigidity, consolidating the cage and plate into a singular modular entity. Nine patients from our surgical centers underwent a procedure of 1-level XLIF with XLPF in selected cases. We observed that XLPF does not extend the intraoperative footprint and provides immediate rigidity to the anterior column without any additional risk of complications and with minimal increased time compared to the traditional cage implant procedure. Although it has been shown that the use of interbody fusion cages with supplemental posterior fixation improves stabilization in all directions, the technique of standalone lateral cages may also have a place in spine surgery in that the stability may be sufficient in selected cases, such as junctional syndrome and in some forms of degenerative scoliosis.

Porous titanium microsphere kyphoplasty for augmentation treatment of osteoporotic vertebral fractures: Technical report and case series

Background

Vertebral augmentation procedures (VAPs) are used in cases of persistent and unresponsive pain in patients with vertebral compression fractures (VCFs). Although VAPs are considered a safe procedure providing quick pain relief and improved physical function, some postoperative complications can occur, for example, bone cement leakage. The material used in this procedure is almost exclusively polymethyl methacrylate (PMMA), which appears to lack biological activity and osteointegration capabilities. In this study, we introduce a new filling system consisting of cannulas preloaded with titanium microspheres, which stabilizes and consolidates the structure of the vertebral body in treating VCFs after the performance of the kyphoplasty procedure.

Methods

We report a retrospective case series of six patients affected by osteoporotic vertebral fractures with worsening back pain, neurologic impairment, and failed conservative treatment who underwent the VAP at our institute, for which the SPHEROPLAST [MT ORTHO s.r.l., Aci Sant'Antonio (CT), Italy] system was used.

Results

The patients had failed an average conservative trial of 3.9 weeks before they presented to us with neurodeficit. There were two men and four women with a mean age of 74.5 years. The average hospital stay was 2 days. There were no reported perioperative complications related to cement injection, such as intraoperative hypoxia, hypotension, pulmonary embolization, myocardial infarction, neurovascular or viscera injury, or death. The VAS score significantly decreased from a mean preoperative of 7.5 (range 6-19) to 3.8 (range 3-5) immediately after surgery and 1.8 (range 1-3).

Conclusion

We report the first clinical results in a series of six patients treated for VCF using the microsphere system after analyzing the clinical results produced by, and the complications that arose from, this new device. In patients with VCF, the VAP using titanium microspheres appears to be a feasible and safe procedure with a low risk of material leakage.

Complex Regional Pain Syndrome after Spine Surgery: A Rare Complication in Mini-Invasive Lumbar Spine Surgery: An Updated Comprehensive Review

BACKGROUND

Complex regional pain syndrome (CRPS) is a postoperative, misdiagnosed condition highlighted only by pain therapists after numerous failed attempts at pain control by the treating surgeon in the case of prolonged pain after surgery. It only occurs rarely after spine surgery, causing the neurosurgeon's inappropriate decision to resort to a second surgical treatment.

METHODS

We performed a systematic review of the literature reporting and analyzing all recognized and reported cases of CRPS in patients undergoing spinal surgery to identify the best diagnostic and therapeutic strategies for this unusual condition. We compare our experience with the cases reported through a review of the literature.

RESULTS

We retrieve 20 articles. Most of the papers are clinical cases showing the disorder's rarity after spine surgery. Most of the time, the syndrome followed uncomplicated lumbar spine surgery involving one segment. The most proposed therapy was chemical sympathectomy and spinal cord stimulation.

CONCLUSION

CRPS is a rare pathology and is rarer after spine surgery. However, it is quite an invalidating disorder. Early therapy and resolution, however, require a rapid diagnosis of the syndrome. In our opinion, since CRPS occurs relatively rarely following spinal surgery, it should not have a substantial impact on the indications for and timing of these operations. Therefore, it is essential to diagnose this rare occurrence and treat it promptly and appropriately.

An update of interbody cages for spine fusion surgeries: from shape design to materials

INTRODUCTION

Discectomy and interbody fusion are widely used in the treatment of intervertebral disc-related diseases. Among them, the interbody cage plays a significant role. However, the complications related to the interbody cage, such as nonunion or pseudoarthrosis, subsidence, loosening, and prolapse of the cage, cannot be ignored. By changing the design and material of the interbody fusion cage, a better fusion effect can be obtained, the incidence of appeal complications can be reduced, and the quality of life of patients after interbody fusion can be improved.

AREAS COVERED

This study reviewed the research progress of cage design and material and discussed the methods of cage design and material to promote intervertebral fusion.

EXPERT OPINION

Current treatment of cervical and lumbar degenerative disease requires interbody fusion to maintain decompression and to promote fusion and reduce the incidence of fusion failure through improvements in implant material, design, internal structure, and function. However, interbody fusion is not an optimal solution for treating vertebral instability.Abbreviations: ACDF, Anterior cervical discectomy and fusion; ALIF, anterior lumbar interbody fusion; Axi-aLIF, axial lumbar interbody fusion; BAK fusion cage, Bagby and Kuslich fusion cage; CADR, cervical artificial disc replacement; DBM, decalcified bone matrix; HA, hydroxyapatite; LLIF/XLIF, lateral or extreme lateral interbody fusion; MIS-TLIF, minimally invasive transforaminal lumbar interbody fusion; OLIF/ATP, oblique lumbar interbody fusion/anterior to psoas; PEEK, Poly-ether-ether-ketone; PLIF, posterior lumbar interbody fusion; ROI-C, Zero-profile Anchored Spacer; ROM, range of motion; SLM, selective melting forming; TLIF, transforaminal lumbar interbody fusion or.

Comparison of the efficacy of expandable interbody fusion cage (EXP-IFC) and non-expandable interbody fusion cage (NE-IFC) in MIS-TLIF for lumbar degenerative diseases: A systematic retrospective study on 62 patients

Objectives

To investigate the clinical and radiographic outcomes of EXP-IFC in single-level MIS-TLIF.

Methods

This study included patients aged ≥18 years who received a single-level MIS-TLIF procedure with at least 1 year of follow-up. Outcome measures: clinical features, preoperative and neurological complications. Imaging analysis included disc height (DH) restoration, surgical and contralateral side foraminal height (FH), lumbar lordosis angle (LL), segmental lordosis (SL). Visual analog scale (VAS) score for low back pain (VAS-LBP) and leg pain (VAS-LP), Oswestry Disability Index (ODI) and Japanese Orthopaedic Association (JOA) score were used to evaluate clinical outcomes. Statistical analysis was performed using independent sample t-test and sample t-test. The significance was set to p < 0.05 in univariate analysis.

Results

A total of 62 patients undergoing single level MIS-TLIFs between January 2017 and January 2019 were included, with 32 NE-IFC 46.9% female, mean age 54.86 ± 11.65, mean body mass index (BMI) 24.59 ± 3.63) and 30 EXP (40% female, mean age 58.32 ± 12.99, mean BMI 24.45 ± 2.76) with no significant differences in demographics. There were no significant differences between two groups in Operative time (OT), Estimated blood loss (EBL) and Length of stay (LOS). No significant differences were found in VAS-LBP, VAS-LP, JOA and ODI in post-operation and the last follow-up between the two groups. The imaging outcome demonstrated that the mean increase in DH was significantly greater for the patients with EXP-IFC than those with NE-IFC group at 1 year follow-up (8.92 ± 0.51 mm EXP-IFC vs. 7.96 ± 0.96 mm NE-IFC, p < 0.001). The mean change in FH of operative and contralateral sides were observed to be significantly higher for the patients with EXP-IFC at 1 year follow-up (operative side:17.67 ± 2.29 mm EXP-IFC vs. 16.01 ± 2.73 mm NE-IFC, p = 0.042; contralateral side:17.32 ± 2.26 mm EXP-IFC vs. 16.10 ± 2.32 mm NE-IFC, p < 0.001), but changes in LL and SL were not significantly different. At the last follow-up, we did not find any significant difference in the fusion rate between the two groups.

Conclusion

Our results indicated that there may be no significant difference in short-term clinical outcomes between EXP-IFC and NE-IFC, but the use of EXP-IFC in MIS-TLIF can provide a significant restoration of disc height, and neural foraminal height compared to NE-IFC.

The Efficacy of Trabecular Titanium Cages to Induce Reparative Bone Activity after Lumbar Arthrodesis Studied through the 18f-Naf PET/CT Scan: Observational Clinical In-Vivo Study

Background: Titanium trabecular cages (TTCs) are emerging implants designed to achieve immediate and long-term spinal fixation with early osseointegration. However, a clear radiological and clinical demonstration of their efficacy has not yet been obtained. The purpose of this study was to evaluate the reactive bone activity of adjacent plates after insertion of custom-made titanium trabecular cages for the lumbar interbody with positron emission tomography (PET)/computed tomography (CT) 18F sodium fluoride (18F-NaF). Methods: This was an observational clinical study that included patients who underwent surgery for degenerative disease with lumbar interbody fusion performed with custom-made TTCs. Data related to the metabolic-reparative reaction following the surgery and its relationship with clinical follow-up from PET/CT performed at different weeks were evaluated. PET/CTs provided reliable data, such as areas showing abnormally high increases in uptake using a volumetric region of interest (VOI) comprising the upper (UP) and lower (DOWN) limits of the cage. Results: A total of 15 patients was selected for PET examination. Timing of PET/CTs ranged from one week to a maximum of 100 weeks after surgery. The analysis showed a negative correlation between the variables SUVmaxDOWN/time (r = −0.48, p = 0.04), ratio-DOWN/time (r = −0.53, p = 0.02), and ratio-MEAN/time (r = −0.5, p = 0.03). Shapiro−Wilk normality tests showed significant results for the variables ratio-DOWN (p = 0.002), ratio-UP (0.013), and ratio-MEAN (0.002). Conclusions: 18F-NaF PET/CT has proven to be a reliable tool for investigating the metabolic-reparative reaction following implantation of TTCs, demonstrating radiologically how this type of cage can induce reparative osteoblastic activity at the level of the vertebral endplate surface. This study further confirms how electron-beam melting (EBM)-molded titanium trabecular cages represent a promising material for reducing hardware complication rates and promoting fusion.

Surgical management of giant calcified thoracic disc herniation and the role of neuromonitoring. The outcome of large mono centric series

PURPOSE

Giant thoracic disc herniations (GTDH) are considered a subgroup of TDHs with worse functional outcomes, a high calcification rate, and a considerable risk of complications. We aimed to determine whether there is a relationship between the extent of calcification of GTDH and outcomes concerning the risk of complications, the surgical technique, and changes in neuromonitoring signals.

METHODS

We present a retrospective analysis of 76 patients undergoing surgery for calcific GTDH. We introduced and defined a radiological definition of the calcified disc into"fully calcified" and "partially calcified." We performed a statistical analysis between clinical and radiological variables, type of surgical procedure, the extent of excision, neuro-monitoring signals, and outcome, comparing a group of 58 "fully-calcified TDH" patients and 18 "partially-calcified TDH" patients.

RESULTS

Fully calcified TDHs, compared with partially calcified TDHs, do not have significant differences in outcome (worse outcome 4/58-6.9% versus 0/18, p = 0.25) and complications (10/58-17.24% versus 4/18-22.2%, p = 0.63); Fully calcified TDH is associated with a higher risk of alterations in neurophysiological potentials (14/58-24.1% versus 0/18, p = 0.02) and subtotal excision (18/58-31% versus 2/18-11%, p = 0.15), without significant differences between the approaches used.

CONCLUSION

Fully calcified TDH group has a similar outcome and complication rate as the partially calcified TDH group, but they are associated with higher intraoperative neuromonitoring signal changes. We introduced a new classificationsystem that guides the approach and helps tocounsel the patients.

Full-Endoscopic Posterior Lumbar Interbody Fusion with Epidural Anesthesia: Technical Note and Initial Clinical Experience with One-Year Follow-Up

Objective

The purpose of this study was to introduce and evaluate the early clinical outcomes of the full-endoscopic posterior lumbar interbody fusion (Endo-PLIF) technique with epidural anesthesia (EA) for single-segment lumbar degenerative diseases.

Methods

In this retrospective case series study, we explored the feasibility and effectiveness of the Endo-PLIF with EA for single-segment lumbar degenerative diseases. Between March 2018 and January 2019, a series of 24 patients with single-segment lumbar degenerative diseases underwent Endo-PLIF surgery and were followed up for a minimum of 12 months (15.21±2.27 months). Clinical outcomes including visual analog scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI) scores, and the Short Form-36 health survey questionnaire (SF-36) were evaluated preoperatively, and postoperatively at 3 days and at 3, 6, and 12-months.

Results

All patients underwent successful single-segment Endo-PLIF surgery. The mean operation time was 209.17±39.49 min, and average amount of bleeding was 43.33±14.87 mL. The VAS for lower extremity pain and back pain significantly improved at 3 days, and at 3, 6, 12 months compared with preoperative, respectively. The ODI scores decreased from 42.04±3.96 to 12.75±2.71 (P<0.001) at preoperative and 12 months postoperatively, respectively. The SF-36 Physical Component Scores (PCS) improved from 34.96±4.63 preoperatively to 52.08±6.05 (P<0.001) at 12 months postoperatively. Additionally, the SF-36 Mental Component Scores (MCS) improved from 39.38±5.70 at preoperative to 53.13±5.97 (P<0.001) at 12 months postoperatively. Two patients experienced dysesthesia, and one patient had a wound infection.

Conclusion

Endo-PLIF with EA is a feasible and valuable technique for the treatment of single-segment lumbar degenerative diseases in selected patients.