Search Results (35)

Background/Objectives: Lateral lumbar interbody fusion (LLIF) has gained popularity as an effective technique for indirect decompression through ligamentotaxis. Despite the perceived importance of using appropriately sized cages for achieving optimal decompression, comprehensive reports on cage size and its impact on indirect decompression are limited. This study aimed to assess the ligamentotaxis effect by measuring the “backward bulging” length in pre- and postoperative MRIs and examining its correlation with cage size and subsidence. Methods: T2 images of 270 patients with lumbar herniated disc and/or lumbar spondylolisthesis (June 2022 to March 2025) were analyzed for 530 intervertebral spaces. Data on gender, age, length of hospital stay, preoperative and postoperative lumbar JOA scores, and the level of the disease were collected. Measurements included backward bulging length, intervertebral height, and cage subsidence. Statistical analysis was performed using StatMate. Surgical procedures involved oblique lateral interbody fusion (OLIF) to minimize impact on the iliopsoas and lumbar plexus. Trial cages starting from 8 mm were sequentially inserted, with confirmation through lateral fluoroscopy. Posterior fixation was performed using percutaneous pedicle screws. Results: Analysis of 530 intervertebral spaces revealed that 70% could accommodate a cage 3 mm or larger than the preoperative intervertebral height. Significant backward bulging shortening (3 mm or more) occurred in 339 spaces, predominantly with larger cages. Only 8.8% of cases (14/159) with a large backward bulging shortening had an intervertebral height extension of 3 mm or less. On the other hand, a large reduction in backward bulging was observed in 91.3% of cases (339/371) with an intervertebral height extension of 3 mm or more. Postoperative cage subsidence was observed in 9.2% (49/530) of all intervertebral spaces and 8.6% (32/371) in spaces where a cage larger than 3 mm was used. There was no statistically significant difference between these two groups. Conclusions: To achieve a sufficient ligamentotaxis effect, it is necessary to select a cage size that allows for an intervertebral height increase of at least 3 mm compared to the preoperative measurement. Full article

Lumbar interbody fusion (LIF) is a standard treatment for spinal instability, yet postoperative subsidence and adjacent segment degeneration (ASD) remain critical challenges. This study evaluates the biomechanical efficacy of personalized porous fusion cages—featuring Gyroid (G-Cage) and Voronoi (V-Cage) architectures—against classic (C-Cage) and personalized (P-Cage) designs, aiming to enhance stability and mitigate subsidence risks. A finite element model of the L3–L4 segment, derived from CT scans of a healthy male volunteer, was developed to simulate six motion modes (compression, rotation, flexion, extension, and left/right bending). Biomechanical parameters, including range of motion (ROM), cage stress, endplate stress, and displacement, were analyzed. The results demonstrated that the V-Cage exhibited superior performance, reducing ROM by 51% in extension, cage stress by 41.7% in compression, and endplate stress by 63.7% in right bending compared to the C-Cage. The porous designs (G-Cage, V-Cage) exhibited biomimetic stress distribution and minimized micromotion, which was attributed to their trabecular-like architectures. These findings highlight the Voronoi-based porous cage as a biomechanically optimized solution, offering enhanced stability and reduced subsidence risk when compared to classic implants. The study underscores the potential of patient-specific porous designs in advancing LIF outcomes, warranting further clinical validation to translate computational insights into practical applications. Full article

Background/Objectives: Despite recent advances in minimally invasive extrapleural lateral approaches, oblique lateral interbody fusion (OLIF) at the upper lumbar level is often difficult and limited to optimal reconstruction. We aimed to compare the radiological outcomes and approach-related complications of OLIF between the upper (L1–2 or L2–3) and lower (L3–4 or L4–5) levels. Methods: This study is a retrospective review of OLIF in the upper (n = 63) and lower (n = 60) lumbar level groups. Radiological parameters included the anterior/posterior disc height, coronal/sagittal disc angle, cage position, cage subsidence, and fusion rate at a postoperative 1-year follow-up. Approach-related complications including pleural/peritoneal lacerations, neurovascular injury, and other organ injuries were examined. Results: The baseline radiological parameters were similar between the two groups (all p > 0.05). At 1-year postoperatively, the anterior disc height (ADH) was significantly greater in the lower-level group (p = 0.031), while no significant differences were observed in the posterior disc height, coronal/sagittal disc angle, cage anterior position, or cage subsidence rate (all p > 0.05). The fusion rates were 97.9% and 95.0% at the upper and lower lumbar levels, respectively (p = 0.146). During OLIF at the upper lumbar level, chest tube insertion due to pleural laceration was observed in 11 (17.5%) cases. One case (1.2%) of segmental artery injury and two cases (3.2%) of pseudo-hernia were attributed to iliohypogastric nerve injury. Conclusions: Although the extrapleural approach in OLIF at the upper lumbar level is often limited, the radiological outcomes were comparable to those of OLIF at the lower lumbar level. Full article

Global oyster reefs have suffered severe degradation due to human activities, environmental pollution, and climate change. The construction of artificial reefs offers a promising strategy to enhance oyster recruitment and mitigate population decline. However, the factors influencing oyster recruitment in artificial frameworks remain largely unclear, and it is still challenging to evaluate the effectiveness of different restoration methods. In this study, a series of oyster reef restoration experiments were conducted in the Tianjin coastal zone to identify key factors affecting recruitment success. These factors included restoration methods (shell string, mesh bag, and mesh cage), seeding with juvenile oysters, oyster shell orientation, and cultch hanging height. Our results indicated that the mesh bag method achieved the highest oyster settlement density in the intertidal zone, while the shell string method supported the fastest growth rates of oysters in the subtidal zone. The lower hanging height of cultches in the artificial frames increased oyster settlement density; however, hanging the cultches too close to the sediment negatively impacted oyster growth rates. Additionally, seeding with juvenile oysters and orienting the rough side of the shell upward enhanced recruitment performance. Oyster settlement density was greater in the intertidal zone (Bagua Shoal) compared to the subtidal zone (Dashentang), while oysters in the subtidal zone exhibited faster growth rates. Using redundancy analysis, the influence of environmental factors on the oyster recruitment performance was assessed. Oyster growth in the subtidal zone was positively correlated with dissolved oxygen and pH, whereas oyster settlement density in the intertidal zone was positively associated with water temperature, chlorophyll a concentration, and salinity. Finally, we evaluated the effectiveness of different restoration methods by considering factors including reef construction costs, oyster settlement abundance, average daily shell growth rate, water purification potential, and reef subsidence. Our results demonstrated that the shell string method was the most effective in the Dashentang subtidal zone, while the mesh bag method with oyster seeding was optimal in the Bagua Shoal intertidal zone. Our findings can provide valuable insights and guidance for oyster reef restoration projects. Full article

(1) Cage subsidence in spine surgery is a frequent clinical challenge. This study aimed to assess a novel screw augmentation technique for Transforaminal Lumbar Interbody Fusion in cadavers of reduced bone mineral density (BMD). (2) Forty human lumbar vertebrae (BMD 84.2 ± 24.4 mgHA/cm³, range 51–119 mgHA/cm³) were assigned to two groups: augmenting screw group and control group. The augmentation technique comprised placement of two additional subcortical screws. Ten constructs per group were loaded with a quasi-static load-to-failure protocol and other ten were cyclically loaded. Failure modes were documented. (3) During the quasi-static load-to-failure testing, the augmenting screw technique showed a significantly higher failure load (1426.0 ± 863.6 N) versus the conventional technique in the control group (682.2 ± 174.5 N, p = 0.032). Cyclic loading revealed higher number of cycles and corresponding load until reaching 5 mm subsidence and significantly higher number of cycles and corresponding load until reaching 10 mm subsidence for the augmenting screw technique (9645 ± 3050; 1164.5 ± 305.0 N) versus the conventional technique in the control group (5395 ± 2340; 739.5 ± 234.0 N, p < 0.05). Failure modes were different and showed bending of the augmenting screws, followed by cut-out. (4) The investigated augmenting screw technique demonstrated higher failure loads and cycles to failure against cage subsidence compared to conventional cage placement. Failure modes were different between the two techniques and may lead to a different kind of complications. Full article

Background/Objectives: The concept of frailty has been recognized as an important issue which can influence postoperative outcomes. We aimed to investigate the influence of frailty on clinical and radiological outcomes in patients undergoing transforaminal lumbar interbody fusion (TLIF) for degenerative spine disease. Methods: A single-center, retrospective cohort study was conducted involving 408 patients in whom 506 expandable interbody devices were implanted. The patients were grouped into vulnerable/frail versus well/fit according to the Canadian Frailty Index. Results: The frail patients were older and had a larger number of fused segments (3.0 vs. 2.4 segments, p = 0.009). In the univariate analysis, the frail patients were more likely to experience a postoperative adverse event (AE) until discharge (OR 1.89, 95% CI 1.22–2.92; p = 0.004), three (OR 1.57, 1.07–2.3; p = 0.021), and 12 months postoperatively (OR 3.77, 1.96–7.24; p < 0.001). Following the multivariable logistic regression analysis, frailty remained an independent risk factor for postoperative AEs at 12 months (OR 3.44, 95% CI 1.69–6.99; p = 0.001). Conclusions: Frailty negatively influenced the rate of AEs until 12 months, while the odds of having a favorable outcome at any time remained unaffected in patients undergoing posterior spinal fusion with TLIF. Future efforts are needed to evaluate whether preoperative medical optimization or prehabilitation may positively impact patient outcomes. Full article

Bone mineral density (BMD) is an essential indicator of bone strength and plays a crucial role in the clinical management of various spinal pathologies. Hounsfield units (HUs) calculated from computed tomography (CT) scans are a well-established, effective, and non-invasive method to determine bone density in the lumbar spine when juxtaposed to dual-energy X-ray absorptiometry (DEXA) scans, the gold standard for assessing trabecular bone density. Only recently have studies begun to investigate and establish HUs as a reliable and valid alternative for bone quality assessment in the cervical spine as well. In addition, multiple recent studies have identified cervical HUs as an accurate predictor of cage subsidence, an undesired complication of anterior cervical discectomy and fusion (ACDF) of anterior cervical corpectomy and fusion (ACCF) procedures. Subsidence involves migration of the spinal fusion cage into vertebral bodies, causing a loss of disk space, negatively altering spine alignment, and possibly necessitating further unwanted surgical intervention. Using the PRISMA-ScR checklist and the registered scoping review protocol (INPLASY2024100126), this review explores the current research on the use of cervical spine HU measurements as both a determinant of BMD and as a prognosticator of postoperative subsidence following cervical spine procedures (i.e., ACDFs and ACCFs) with the aim of improving clinical and surgical outcomes. Full article

Study Design: This was a single-institution, retrospective cohort study. Objective: The objective of this study was to assess a surgical technique for spinal reconstruction after corpectomy, integrating an allograft/autograft within a vertebral body replacement cage linked to spinal rods via pedicle screws. This method aims to enhance biomechanical stability and promote long-term fusion without cage endcaps. Summary of Background data: Recent advancements in spinal surgery feature innovative constructs that improve healing and fusion rates. FDA-approved mesh cages provide enhanced stability and superior fusion with fewer complications. Our approach combines allografts/autografts with vertebral replacements, using a pedicle screw through the cage for significant biomechanical enhancement. Methods: Two patients undergoing cervical and lumbar spinal reconstructions due to different pathologies were selected. The surgical technique involved shaping the allograft/autograft to fit precisely within the cage, extending beyond its ends to facilitate fusion at both ends, and securing the construct to the spinal rods with pedicle screws for added stability. Patient outcomes were assessed based on post-operative stability, fusion rates, and the presence of any complications. Results: Both cases successfully utilized the technique, achieving stabilization and fusion. Improvements were noted in post-operative recovery. There were no instances of cage subsidence, or any significant complications directly related to the novel construct. Conclusions: Our case series highlights a post-corpectomy reconstruction technique involving a mesh cage construct integrated with an autograft/allograft and connected to posterior instrumentation for enhanced stability. This technique was applied successfully in two cases, demonstrating its feasibility, durability, and potential to promote biological integration. Further studies with larger cohorts and extended follow-up periods are necessary to refine the approach for wider clinical use. Full article

Background: Oblique lumbar interbody fusion (OLIF) is a minimally invasive technique used to manage degenerative lumbar conditions. The presence of vacuum phenomenon (VP) and associated endplate sclerosis may increase the risk of cage subsidence. This study evaluated the relationship between VP grade, endplate sclerosis, and subsidence in OLIF. Methods: This retrospective cohort study included 165 patients who underwent a single-level OLIF for lumbar stenosis. Patients were stratified into VP grades (0–3) based on preoperative computed tomography scans. Disc height, endplate sclerosis, and cage subsidence were radiologically assessed. Clinical outcomes, including back and leg pain visual analog scale, Oswestry Disability Index, and EuroQol-5 Dimension, were measured preoperatively and at follow-up. Results: High VP grades were associated with low preoperative disc height and increased endplate sclerosis. Although no significant differences in clinical outcomes or final fusion rates across VP grades were observed, the subsidence rate increased with VP grade, with a significant difference between VP grades 1 and 2 (p = 0.045) and between VP grades 2 and 3 (p = 0.032), indicating that subsidence rates increased as the VP grade advanced. Conclusions: High VP grades, particularly grades 2 and 3, may increase the risk of cage subsidence following OLIF. Therefore, VP grading may be worth considering during surgical planning to reduce the subsidence risk and improve outcomes. Full article

Background: This study aimed to evaluate the impact of iliac crest height on clinical and radiological outcomes following oblique lateral interbody fusion (OLIF) at the L4–5 level. Methods: Data of patients who underwent single-level OLIF at the L4–5 level for degenerative spinal stenosis were retrospectively analyzed. The patients were categorized into three groups based on their iliac crest height measured relative to the L4 and L5 pedicles. Categorical and quantitative analyses, including univariate and multivariate logistic regressions, were performed to identify subsidence predictors. Clinical outcomes, including visual analog scale scores for back and leg pain, were assessed over a minimum 2-year follow-up. Results: No significant differences in cage obliquity were observed across the iliac crest height groups (axial angles, p = 0.39; coronal angles, p = 0.79). However, subsidence was significantly more common in patients with higher iliac crest heights, particularly at crest level III, where the subsidence rate reached 43% (p = 0.01). Subsidence was predominantly associated with damage to the L5 endplate, which occurred in 83% of subsidence cases at crest level III. A cutoff value of 12 mm for iliac crest height, above which the risk of subsidence significantly increased, was identified (AUC = 0.688, p = 0.042). Conclusions: Iliac crest height is a critical factor for predicting subsidence following OLIF at the L4–5 level. Surgeons should consider alternative strategies and meticulous preoperative planning in patients with an iliac crest height ≥ 12 mm to reduce the risk of adverse outcomes. Further studies are needed to validate these findings and to explore their long-term implications. Full article

Introduction: The choice of prosthesis for vertebral body reconstruction (VBR) remains a controversial issue due to the lack of a reliable solution. The subsidence rate of the most commonly used titanium mesh cages (TMC) ranges from 42.5% to 79.7%. This problem is primarily caused by the differences in the elastic modulus between the TMC and bone. This review aims to summarize the clinical and radiological outcomes of new 3D-printed artificial vertebral bodies (3DP AVB). Methods: A literature search of PubMed, Scopus and Google Scholar was conducted to extract relevant studies. After screening the titles and abstracts, a total of 50 articles were selected for full-text analysis. Results: Preliminary data suggest fewer implant-related complications with 3DP AVB. Most comparative studies indicate significantly lower subsidence rates, reduced operation times and decreased intraoperative blood loss. However, the scarcity of randomized clinical trials and the high variability of the results warrant caution. Conclusion: Most literature data show an advantage of 3DP AVB in terms of the operation time, intraoperative blood loss and subsidence rate. However, long manufacturing times, high costs and regulatory issues are this technology’s main drawbacks. Full article

Background: Standard oblique cages cannot cover endplates side-to-side, which is an important biomechanical factor for reducing the risk of cage subsidence and for restoring correct segmental lordosis. The aim of this study is to evaluate the radiological and clinical results of a new oblique lumbar interbody fusion (OLIF) axially expandable cage. Methods: This is a prospective observational case–control study. From March 2018 to June 2020, 28 consecutive patients with lumbar degenerative disease underwent an ATP approach, with the insertion of a new axially expandable cage, which was used as a stand-alone procedure or followed by posterior percutaneous pedicle fixation. Results: Twenty-eight patients in both groups met the inclusion criteria. The mean follow-up time was 31.2 months (range of 13–37). The clinical results were not significantly different, although in the control group, two major intraoperative complications were recorded, and slight improvements in ODI and SF-36 scores were observed in the study group. The radiological results showed a less frequent incidence of subsidence and a higher rate of fusion in the study group compared to controls. Conclusions: The axially expandable oblique cage for lumbar inter body fusion, specifically designed for the ATP approach, represents an innovation and a technical improvement. The insertion and the axial expansion technique are safe and easy. The large footprint could obtain solid and effective arthrodesis, potentially reducing the risk of subsidence. Full article

Background: Teriparatide is an anabolic agent for osteoporosis and is believed to improve the bone healing process. Previous studies showed that teriparatide could enhance not only fracture healing but also spine fusion. It has been reported that use of teriparatide could promote the spine fusion process and decrease mechanical complications. However, there was no consensus regarding optimal treatment duration. The purpose of this study was to compare surgical outcomes between short-duration and long-duration teriparatide treatment after lumbar fusion surgery in elderly patients. Materials and Methods: All consecutive patients older than 60 years who underwent 1-level lumbar fusion surgery for degenerative diseases between January 2015 and December 2019 were retrospectively reviewed. Based on the duration of teriparatide treatment (daily subcutaneous injection of 20 µg teriparatide), patients were subdivided into two groups: a short-duration (SD) group (<6 months) and a long-duration (LD) group (≥6 months). Mechanical complications, such as screw loosening, cage subsidence, and adjacent vertebral fractures, were investigated. Postoperative 1-year union rate was also evaluated on computed tomography. Clinical outcomes were recorded using visual analog scale (VAS) and Oswestry Disability Index (ODI). Between-group differences for these radiographic and clinical outcomes were analyzed. Results: Ninety-one patients were reviewed in this study, including sixty patients in the SD group and thirty-one patients in the LD group. Their mean age was 72.3 ± 6.2 years, and 79 patients were female. Mean T-score was −3.3 ± 0.8. Cage subsidence (6.7% vs. 3.2%), screw loosening (28.3% vs. 35.5%), and adjacent vertebral fracture (6.7% vs. 9.7%) were not significantly different between the SD and LD groups. Union rate at 1-year postoperative was 65.0% in the SD group and 87.1% in the LD group (p = 0.028). Both groups showed improvement in VAS and ODI after surgery. However, the differences of VAS from preoperative to 6 months and 1 year postoperative were significantly higher in the LD group. Conclusions: Longer teriparatide treatment after lumbar fusion surgery resulted in a higher union rate at 1-year postoperative than the shorter treatment. Also, it could be more beneficial for clinical outcomes. Full article

Introduction: Anterior cervical discectomy and fusion (ACDF) for cervical disc herniation (CDH) is commonly performed. Specific post-operative complications include dysphagia, dysphonia, cervicalgia, adjacent segment disorder, cage subsidence, and infections. However, interscapular pain is commonly reported by these patients after surgery, although its mechanisms have not been clarified yet. Methods: This retrospective series of 31 patients undergoing ACDF for CDH at a single Academic Hospital. Baseline and post-operative clinical, radiological, and surgical data were analyzed. The linear regression analysis was conducted to identify any factor independently influencing the incidence rate of post-operative interscapular pain. Results: The mean age was 57.6 ± 10.8 years, and the M:F ratio was 2.1. Pre-operative mean VAS-arm was 7.15 ± 0.81 among the 20 patients reporting brachialgia, and mean VAS-neck was 4.36 ± 1.43 among those 9 patients reporting cervicalgia. At 1 month, interscapular pain was still reported by 8 out of the 17 patients who experienced it post-operatively, and it was recovered in all patients after 2 months. The regression analysis showed that interscapular pain was not directly associated with age (p = 0.74), gender (p = 0.46), smoking status (p = 0.44), diabetes (0.42), pre-operative brachialgia (p = 0.21) or cervicalgia (p = 0.48), symptoms duration (p = 0.13), baseline VAS-arm (p = 0.11), VAS-neck (p = 0.93), or mJOA (p = 0.63) scores, or disc height modification (p = 0.90). However, the post-operative increase in the mean zygapophyseal joint rim distance was identified as an independent factor in determining interscapular pain (p = 0.02). Conclusions: Our study revealed that the onset of interscapular pain following ACDF may be determined by over distraction of the zygapophyseal joint rim. Then, proper sizing of prosthetic implants could reduce this painful complication. Full article

Background: In the evolving landscape of anterior cervical discectomy and fusion (ACDF), the integration of biomechanical advancements and proper fusion-enhancing materials is crucial for optimizing patient outcomes. This case series evaluates the efficacy and clinical implications of employing zero-profile polyetheretherketone (PEEK) cages filled with biphasic calcium phosphate (BCP) in ACDF procedures, focusing on fusion and subsidence rates alongside patient disability, residual pain, and quality of life. Methods: This case series comprises 76 consecutive patients, with a median follow-up of 581 days. The Bridwell classification system was used for assessing fusion rates while subsidence occurrence was recorded, correlating these radiographic outcomes with clinical implications. Results: The results demonstrated a satisfactory fusion rate (76.4% for grades I and II). The subsidence rate was low (6.74% of segments). Significant clinical improvements were observed in pain, disability, and quality-of-life metrics, aligning with the minimum clinically important difference thresholds; however, subgroup analyses demonstrated that subsidence or pseudoarthrosis group improvement of PROMs was not statistically significant with respect to baseline. ANOVA analyses documented that subsidence has a significant weight over final follow-up pain and disability outcomes. No dysphagia cases were reported. Conclusions: These findings underscore the efficacy of zero-profile PEEK cages filled with BCP in ACDF, highlighting their potential to improve patient outcomes while minimizing complications. Pseudoarthrosis and subsidence have major implications over long-term PROMs. The study reinforces the importance of selecting appropriate surgical materials to enhance the success of ACDF procedures. Full article