Biological performance of a bioabsorbable magnesium-magnesium phosphate cement interbody fusion cage in a porcine lumbar interbody fusion model: a feasibility study.

PURPOSE: The aim of the study was to evaluate the feasibility of a bioabsorbable cage consisting of magnesium and magnesium phosphate cement (MPC) in a porcine lumbar interbody fusion model. METHODS: Twelve male Ba-Ma mini pigs underwent lumbar discectomy and fusion with an Mg-MPC cage or a PEEK cage at the L3/L4 and L4/L5 level. Computed tomography (CT) scans were made to evaluate the distractive property by comparing average disc space height (DSH) before and at 6, 12, and 24 weeks after the operation. After the lumbar spines were harvested at 6 or 24 weeks after the operation, micro-CT examination was conducted to analyze the fusion rate, and stiffness of motion segments was investigated through mechanical tests. A histological study was performed to evaluate the tissue type, inflammation, and osteolysis in the intervertebral space. RESULTS: CT scans showed no significant difference between the two groups in average DSH at each time point. Micro-CT scans revealed an equal fusion rate in both groups (0% at 6 weeks, 83.3% at 24 weeks). Both groups showed time-dependent increases in stability, the Mg-MPC cages achieved an inferior stiffness at 6 weeks and a comparable stiffness at 24 weeks. Histologic evaluation showed the presence of newly formed bone in both groups. However, empty spaces were observed at the interface or around the Mg-MPC cages. CONCLUSION: Compared with the PEEK cages, the Mg-MPC cages achieved comparable distraction, fusion rate, and spinal stability at 24 weeks after the operation. However, due to inferior stiffness at the early stage and fast degradation, further modification of material composition and design are necessary.

Comparison of Fusion Rate and Clinical Outcomes in Minimally Invasive and Conventional Posterior Fusion for Lumbar Degenerative Disease: A Network Meta-Analysis.

BACKGROUND: The fusion rate, clinical efficacy, and complications of minimally invasive fusion surgery and open fusion surgery in the treatment of lumbar degenerative disease are still unclear. METHODS: We conducted a literature search using PubMed, Embase, Cochrane Library, CNKI, and WANFANG databases. RESULTS: This study included 38 retrospective studies involving 3097 patients. Five intervention modalities were considered: unilateral biportal endoscopic-lumbar interbody fusion (UBE-LIF), percutaneous endoscopic-lumbar interbody fusion (PE-LIF), minimally invasive-transforaminal lumbar interbody fusion (MIS-TLIF), transforaminal lumbar interbody fusion (TLIF), and posterior lumbar interbody fusion (PLIF). Quality assessment indicated that each study met acceptable quality standards. PE-LIF demonstrated reduced low back pain (Odds Ratio = 0.50, Confidence Interval: 0.38-0.65) and lower complication rate (Odds Ratio = 0.46, Confidence Interval: 0.25-0.87) compared to PLIF. However, in indirect comparisons, PE-LIF showed the lowest fusion rates, with the ranking as follows: UBE-LIF (83.2%) > MIS-TLIF (59.6%) > TLIF (44.3%) > PLIF (39.8%) > PE-LIF (23.1%). With respect to low back pain relief, PE-LIF yielded the best results, with the order of relief as follows: PE-LIF (96.4%) > MIS-TLIF (64.8%) > UBE-LIF (62.6%) > TLIF (23.0%) > PLIF (3.2%). Global and local consistency tests showed satisfactory results, and heterogeneity tests indicated good stability. CONCLUSIONS: Compared to conventional open surgery, minimally invasive fusion surgery offered better scores for low back pain and Oswestry Disability Index, lower complication rates, reduced bleeding, and shorter hospital stays. However, minimally invasive fusion surgery did not show a significant advantage in terms of fusion rate and had a longer operative time.

The clinical efficacy of Medial Sustain Nail(MSN) and Proximal femoral nail anti-rotation(PFNA) for fixation of medial comminuted trochanteric fractures: a prospective randomized controlled trial.

PURPOS: To evaluate the clinical efficacy of the Medial Sustain Nail (MSN) for medial comminuted trochanteric fractures fixation in comparison to Proximal Femoral Nail Antirotation (PFNA) through a clinical study. METHODS: A non-inferiority randomized controlled trial was conducted at a single centre between July 2019 and July 2020. Fifty patients diagnosed comminuted trochanteric fractures were randomly assigned to either the MSN group (n = 25) or the PFNA group (n = 25). A total of forty-three patients were included in the final study analysis. The primary outcome measure was Short Form 36 health surgery physical component summary (SF-36 PCS) score. Secondary outcomes included the Oxford Hip Scores (OHS), weight bearing, complication relate to implant and so on. This study was not blined to surgeons, but to patients and data analysts. RESULTS: The MSN demonstrated significantly better functional outcomes as measured by SF-36 PCS and OHS at six months postoperative compared to PFNA (p < 0.05). Union of fractures in the MSN group reached 90.9% at three months after surgery, whereas the PFNA group achieved a union rate of 57.1% (p < 0.05). Furthermore, weight-bearing time of MSN group was earlier than PFNA group (p < 0.05). Additionally, complications related to implant usage were more prevalent in the PFNA group (33.3%) compared to the MSN group (4.5%) (p < 0.05). CONCLUSION: MSN exhibited superior quality of life outcomes compared to PFNA at six months postoperative. This indicates that MSN effectively reconstructs medial femoral support in patients with comminuted trochanteric fractures, which facilitates early weight-bearing and accelerates the recovery process. TRIAL REGISTRATION: Trial registration number: NCT01437176, Date of the trial registration:2011-9-1, Date of commencement of the study:2011-9, Date of enrolment/recruitment of the study subjects:2019-7.

Clinical efficacy and complications of MIS-TLIF and TLIF in the treatment of upper lumbar disc herniation: a comparative study.

BACKGROUND: The optimal treatment modality for upper lumbar disc herniation remains unclear. Herein, we compared the clinical efficacy and application value of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and transforaminal lumbar interbody fusion (TLIF) for upper lumbar disc herniation. We aimed to provide new evidence to guide surgical decisions for treating this condition. METHODS: We retrospectively analyzed the clinical data of 81 patients with upper lumbar disc herniation admitted between January 2017 and July 2018, including 41 and 40 patients who underwent MIS-TLIF and TLIF, respectively. Demographic characteristics, preoperative functional scores, perioperative indicators, and postoperative complications were compared. We performed consecutive comparisons of visual analog scale (VAS) scores of the lumbar and leg regions, Oswestry disability index (ODI), Japanese Orthopaedic Association scores (JOA), and MacNab scores at the final follow-up, to assess clinical outcomes 5 years postoperatively. RESULTS: VAS scores of the back and legs were significantly lower in the MIS-TLIF than the TLIF group at 3 months and 1 year postoperatively (P < 0.05). Intraoperative bleeding and postoperative hospitalization time were significantly lower, and the time to return to work/normal life was shorter in the MIS-TLIF than in the TLIF group (P < 0.05). The differences in JOA scores and ODI scores between the two groups at 3 months, 1 year, and 3 years postoperatively were statistically significant (P < 0.05). CONCLUSION: The early clinical efficacy of MIS-TLIF was superior to that of TLIF, but no differences were found in mid-term clinical efficacy. Further, MIS-TLIF has the advantages of fewer medical injuries, shorter hospitalization times, and faster postoperative functional recovery.

Inhibiting the "isolated island" effect in simulated bone defect repair using a hollow structural scaffold design.

The treatment of bone tissue defects remains a complicated clinical challenge. Recently, the bone tissue engineering (BTE) technology has become an important therapeutic approach for bone defect repair. Researchers have improved the scaffolds, cells, and bioactive factors used in BTE through various existing bone repair material preparation strategies. However, due to insufficient vascularization, inadequate degradation, and fibrous wrapping, most BTE scaffolds impede new bone ingrowth and the reconstruction of grid-like connections in the middle and late stages of bone repair. These non-degradable scaffolds become isolated and disordered like independent "isolated islands", which leads to the failure of osteogenesis. Consequently, we hypothesized that the "island effect" prevents successful bone repair. Accordingly, we proposed a new concept of scaffold modification-osteogenesis requires a bone temporary shelter (also referred to as the empty shell osteogenesis concept). Based on this concept, we consider that designing hollow structural scaffolds is the key to mitigating the "isolated island" effect and enabling optimal bone regeneration and reconstruction.

Three-Dimensional-Printed Spherical Hollow Structural Scaffolds for Guiding Critical-Sized Bone Regeneration.

The treatment of bone tissue defects continues to be a complex medical issue. Recently, three-dimensional (3D)-printed scaffold technology for bone tissue engineering (BTE) has emerged as an important therapeutic approach for bone defect repair. Despite the potential of BTE scaffolds to contribute to long-term bone reconstruction, there are certain challenges associated with it including the impediment of bone growth within the scaffolds and vascular infiltration. These difficulties can be resolved by using scaffold structural modification strategies that can effectively guide bone regeneration. This study involved the preparation of biphasic calcium phosphate spherical hollow structural scaffolds (SHSS) with varying pore sizes using 3D printing (photopolymerized via digital light processing). The chemical compositions, microscopic morphologies, mechanical properties, biocompatibilities, osteogenic properties, and impact on repairing critical-sized bone defects of SHSS were assessed through characterization analyses, in vitro cytological assays, and in vivo biological experiments. The results revealed the biomimetic properties of SHSS and their favorable biocompatibility. The scaffolds stimulated cell adhesion, proliferation, differentiation, and migration and facilitated the expression of osteogenic genes and proteins, including Col-1, OCN, and OPN. Furthermore, they could effectively repair a critical-sized bone defect in a rabbit femoral condyle by establishing an osteogenic platform and guiding bone regeneration in the defect region. This innovative strategy presents a novel therapeutic approach for assessing critical-sized bone defects.

Comparison between oblique lumbar interbody fusion and posterior lumbar interbody fusion for the treatment of lumbar degenerative diseases: a systematic review and meta-analysis.

BACKGROUND: Although oblique lumbar interbody fusion (OLIF) has produced good results for lumbar degenerative diseases (LDDs), its efficacy vis-a-vis posterior lumbar interbody fusion (PLIF) remains controversial. This meta-analysis aimed to compare the clinical efficacy of OLIF and PLIF for the treatment of LDDs. METHODS: A comprehensive assessment of the literature was conducted, and the quality of retrieved studies was assessed using the Newcastle-Ottawa Scale. Clinical parameters included the visual analog scale (VAS), and Oswestry Disability Index (ODI) for pain, disability, and functional levels. Statistical analysis related to operative time, intraoperative bleeding, length of hospital stay, lumbar lordosis angle, postoperative disc height, and complication rates was performed. The PROSPERO number for the present systematic review is CRD42023406695. RESULTS: In total, 574 patients (287 for OLIF, 287 for PLIF) from eight studies were included. The combined mean postoperative difference in ODI and lumbar VAS scores was - 1.22 and - 0.43, respectively. In postoperative disc, height between OLIF and PLIF was 2.05. The combined advantage ratio of the total surgical complication rate and the mean difference in lumbar lordosis angle between OLIF and PLIF were 0.46 and 1.72, respectively. The combined mean difference in intraoperative blood loss and postoperative hospital stay between OLIF and PLIF was - 128.67 and - 2.32, respectively. CONCLUSION: Both the OLIF and PLIF interventions showed good clinical efficacy for LDDs. However, OLIF demonstrated a superior advantage in terms of intraoperative bleeding, hospital stay, degree of postoperative disc height recovery, and postoperative complication rate.

Comparison between Novel Anatomical Locking Guide Plate and Conventional Locking Plate for Acetabular Fractures: A Finite Element Analysis.

The treatment of complex acetabular fractures remains a complicated clinical challenge. Our self-designed novel anatomical locking guide plate (NALGP) has previously shown promising potential in T-shaped acetabular fractures (TAF), but a direct comparison with conventional fixations is yet to be made. The TAF model was established based on a volunteer's computer tomography data and then fixed with double column locking plates (DLP), a posterior column locking plate with anterior column screws (LPACS), and our NALGP. Forces of 200 N, 400 N, and 600 N were then loaded on the model vertically downward, respectively. The stress distribution and peaks and maximum displacements at three sites were assessed. We found that the stress area of all three plates was mainly concentrated around the fracture line, while only the matching screws of the NALGP showed no obvious stress concentration points. In addition, the NALGP and DLP showed significantly less fracture fragment displacement than the LPACS at the three main fracture sites. The NALGP was found to have less displacement than DLP at the posterior column and ischiopubic branch sites, especially under the higher loading forces of 400 N and 600 N. The fixation stability of the NALGP for TAF was similar to that of DLP but better than that of LPACS. Moreover, the NALGP and its matching screws have a more reasonable stress distribution under different loads of force and the same strength as the LPACS.

Biomechanical effects of iatrogenic muscle-ligaments complex damage on adjacent segments following posterior lumbar interbody fusion: A finite element analysis.

OBJECTIVE: To analyze the biomechanical effects of proximal iatrogenic muscle-ligaments complex (MLC) damage on adjacent segments following posterior lumbar interbody fusion (PLIF) by finite element (FE) analysis. METHODS: The multifidus muscle force was loaded in the validated intact lumbosacral finite element model. Based on whether undergoing PLIF or the proximal MLC damage, three models were established. Range of motion (ROM) and the maximum von Mises (VM) stress of adjacent segments were analyzed, as well as the average muscle force and work capacity in four loading directions. RESULTS: PLIF results in significant changes in ROM and stress. ROM changed significantly in the upper adjacent segment, the PLIF model changed the most in extension, and the largest change in the lower adjacent segment occurred after MLC damage. The VM stress of the upper adjacent segment occurred in extension of the PLIF model, and that of the lower adjacent segment occurred in rotation after MLC damage. In flexion, ROM, and stress of the damaged MLC fusion model were significantly increased compared with the normal and PLIF models, there was a stepwise amplification. The average muscle force comparison of three models was 5.8530, 12.3185, and 13.4670 N, respectively. The total work capacity comparison was close to that of muscle force. CONCLUSION: PLIF results in increased ROM and the VM stress of adjacent segments, the proximal MLC damage will aggravate this change. This may increase the risk of ASD and chronic low back pain. Preserving the proximal MLC reduces the biomechanical effects on adjacent segments.

Epitranscriptomic subtyping, visualization, and denoising by global motif visualization.

Advances in sequencing technologies have empowered epitranscriptomic profiling at the single-base resolution. Putative RNA modification sites identified from a single high-throughput experiment may contain one type of modification deposited by different writers or different types of modifications, along with false positive results because of the challenge of distinguishing signals from noise. However, current tools are insufficient for subtyping, visualization, and denoising these signals. Here, we present iMVP, which is an interactive framework for epitranscriptomic analysis with a nonlinear dimension reduction technique and density-based partition. As exemplified by the analysis of mRNA m5C and ModTect variant data, we show that iMVP allows the identification of previously unknown RNA modification motifs and writers and the discovery of false positives that are undetectable by traditional methods. Using putative m6A/m6Am sites called from 8 profiling approaches, we illustrate that iMVP enables comprehensive comparison of different approaches and advances our understanding of the difference and pattern of true positives and artifacts in these methods. Finally, we demonstrate the ability of iMVP to analyze an extremely large human A-to-I editing dataset that was previously unmanageable. Our work provides a general framework for the visualization and interpretation of epitranscriptomic data.

Functionalized 3D-Printed PLA Biomimetic Scaffold for Repairing Critical-Size Bone Defects.

The treatment of critical-size bone defects remains a complicated clinical challenge. Recently, bone tissue engineering has emerged as a potential therapeutic approach for defect repair. This study examined the biocompatibility and repair efficacy of hydroxyapatite-mineralized bionic polylactic acid (PLA) scaffolds, which were prepared through a combination of 3D printing technology, plasma modification, collagen coating, and hydroxyapatite mineralization coating techniques. Physicochemical analysis, mechanical testing, and in vitro and animal experiments were conducted to elucidate the impact of structural design and microenvironment on osteogenesis. Results indicated that the PLA scaffold exhibited a porosity of 84.1% and a pore size of 350 µm, and its macrostructure was maintained following functionalization modification. The functionalized scaffold demonstrated favorable hydrophilicity and biocompatibility and promoted cell adhesion, proliferation, and the expression of osteogenic genes such as ALP, OPN, Col-1, OCN, and RUNX2. Moreover, the scaffold was able to effectively repair critical-size bone defects in the rabbit radius, suggesting a novel strategy for the treatment of critical-size bone defects.

DLP-printed GelMA-PMAA scaffold for bone regeneration through endochondral ossification.

Intramembranous ossification (IMO) and endochondral ossification (ECO) are two pathways of bone regeneration. The regeneration of most bone, such as limb bone, trunk bone, and skull base bone, mainly occurs in the form of endochondral ossification, which has also become one of the effective ways for bone tissue engineering. In this work, we prepared a well-structured and biocompatible methacrylated gelatin/polymethacrylic acid (GelMA/PMAA) hydrogel by digital light processing (DLP) printing technology, which could effectively chelate iron ions and continuously activate the hypoxia-inducible factor-1 alpha (HIF-1α) signaling pathway to promote the process of endochondral ossification and angiogenesis. The incorporation of PMAA endowed the hydrogel with remarkable viscoelasticity and high efficacy in chelation of iron ions, giving rise to the activation of HIF-1α signaling pathway, improving chondrogenic differentiation in the early stage, and facilitating vascularization in the later stage and bone remodeling. Therefore, the findings have significant implications on DLP printing technology of endochondral osteogenesis induced by the iron-chelating property of biological scaffold, which will provide an effective way in the development of novel bone regeneration.

First-Aid Hydrogel Wound Dressing with Reliable Hemostatic and Antibacterial Capability for Traumatic Injuries.

First-aid for severe traumatic injuries in the battlefield or pre-hospital environment, especially for skin defects or visceral rupture, remains a substantial medical challenge even in the context of the rapidly evolving modern medical technology. Hydrogel-based biomaterials are highly anticipated for excellent biocompatibility and bio-functional designability. Yet, inadequate mechanical and bio-adhesion properties limit their clinical application. To address these challenges, a kind of multifunctional hydrogel wound dressing is developed with the collective multi-crosslinking advantages of dynamic covalent bonds, metal-catechol chelation, and hydrogen bonds. The mussel-inspired design and zinc oxide-enhanced cohesion strategy collaboratively reinforce the hydrogel's bio-adhesion in bloody or humoral environments. The pH-sensitive coordinate Zn2+ -catechol bond and dynamic Schiff base with reversible breakage and reformation equip the hydrogel dressing with excellent self-healing and on-demand removal properties. In vivo evaluation in a rat ventricular perforation model and Methicillin-resistant Staphylococcus aureus (MRSA)-infected full-thickness skin defect model reveal excellent hemostatic, antibacterial and pro-healing effectiveness of the hydrogel dressing, demonstrating its great potential in dealing with severe bleeding and infected full-thickness skin wounds.

Biomechanical effect of proximal multifidus injury on adjacent segments during posterior lumbar interbody fusion: a finite element study.

BACKGROUND: Adjacent segment degeneration (ASD) is a common complication of lumbar interbody fusion; the paraspinal muscles significantly maintain spinal biomechanical stability. This study aims to investigate the biomechanical effects of proximal multifidus injury on adjacent segments during posterior lumbar interbody fusion (PLIF). METHODS: Data from a lumbosacral vertebral computed tomography scan of a healthy adult male volunteer were used to establish a normal lumbosacral vertebral finite element model and load the muscle force of the multifidus. A normal model, an L4/5 PLIF model (PFM) based on a preserved proximal multifidus, a total laminectomy PLIF model (TLPFM), and a hemi-laminectomy PLIF model based on a severed proximal multifidus were established, respectively. The range of motion (ROM) and maximum von Mises stress of the upper and lower adjacent segments were analyzed along with the total work of the multifidus muscle force. RESULTS: This model verified that the ROMs of all segments with four degrees of freedom were similar to those obtained in previous research data, which validated the model. PLIF resulted in an increased ROM and maximum von Mises stress in the upper and lower adjacent segments. The ROM and maximum von Mises stress in the TLPFM were most evident in the upper adjacent segment, except for lateral bending. The ROM of the lower adjacent segment increased most significantly in the PFM in flexion and extension and increased most significantly in the TLPFM in lateral bending and axial rotation, whereas the maximum von Mises stress of the lower adjacent segment increased the most in the TLPFM, except in flexion. The muscle force and work of the multifidus were the greatest in the TLPFM. CONCLUSIONS: PLIF increased the ROM and maximum von Mises stress in adjacent cranial segments. The preservation of the proximal multifidus muscle contributes to the maintenance of the physiological mechanical behavior of adjacent segments, thus preventing the occurrence and development of ASD.

Application of photocrosslinkable hydrogels based on photolithography 3D bioprinting technology in bone tissue engineering.

Bone tissue engineering (BTE) has been proven to be an effective method for the treatment of bone defects caused by different musculoskeletal disorders. Photocrosslinkable hydrogels (PCHs) with good biocompatibility and biodegradability can significantly promote the migration, proliferation and differentiation of cells and have been widely used in BTE. Moreover, photolithography 3D bioprinting technology can notably help PCHs-based scaffolds possess a biomimetic structure of natural bone, meeting the structural requirements of bone regeneration. Nanomaterials, cells, drugs and cytokines added into bioinks can enable different functionalization strategies for scaffolds to achieve the desired properties required for BTE. In this review, we demonstrate a brief introduction of the advantages of PCHs and photolithography-based 3D bioprinting technology and summarize their applications in BTE. Finally, the challenges and potential future approaches for bone defects are outlined.

3D-Printed GelMA/PEGDA/F127DA Scaffolds for Bone Regeneration.

Tissue-engineered scaffolds are an effective method for the treatment of bone defects, and their structure and function are essential for bone regeneration. Digital light processing (DLP) printing technology has been widely used in bone tissue engineering (BTE) due to its high printing resolution and gentle printing process. As commonly used bioinks, synthetic polymers such as polyethylene glycol diacrylate (PEGDA) and Pluronic F127 diacrylate (F127DA) have satisfactory printability and mechanical properties but usually lack sufficient adhesion to cells and tissues. Here, a compound BTE scaffold based on PEGDA, F127DA, and gelatin methacrylate (GelMA) was successfully prepared using DLP printing technology. The scaffold not only facilitated the adhesion and proliferation of cells, but also effectively promoted the osteogenic differentiation of mesenchymal stem cells in an osteoinductive environment. Moreover, the bone tissue volume/total tissue volume (BV/TV) of the GelMA/PEGDA/F127DA (GPF) scaffold in vivo was 49.75 ± 8.50%, higher than the value of 37.10 ± 7.27% for the PEGDA/F127DA (PF) scaffold and 20.43 ± 2.08% for the blank group. Therefore, the GPF scaffold prepared using DLP printing technology provides a new approach to the treatment of bone defects.

A Super Tough, Rapidly Biodegradable, Ultrafast Hemostatic Bioglue.

Death happening due to massive hemorrhage has been involved in military conflicts, traffic accidents, and surgical injuries of various human disasters. Achieving rapid and effective hemostasis to save lives is crucial in urgent massive bleeding situations. Herein, a covalent cross-linked AG-PEG glue based on extracellular matrix-like amino-gelatin (AG) and PEG derivatives is developed. The AG-PEG glue gelatinizes fast and exhibits firm and indiscriminate close adhesion with various moist tissues upon being dosed. The formed glue establishes an adhesive and robust barrier to seal the arterial, hepatic, and cardiac hemorrhagic wounds, enabling it to withstand up to 380 mmHg blood pressure in comparison with normal systolic blood pressure of 60-180 mmHg. Remarkably, massive bleeding from a pig cardiac penetrating hole with 6 mm diameter is effectively stopped using the glue within 60 s. Postoperative indexes of the treated pig gradually recover and the cardiac wounds regrow significantly at 14 days. Possessing on-demand solubility, self-gelling, and rapid degradability, the AG-PEG glue may provide a fascinating stop-bleeding approach for clinical hemostasis and emergency rescue.

Biomechanical studies of different numbers and positions of cage implantation on minimally invasive transforaminal interbody fusion: A finite element analysis.

Background: The position and number of cages in minimally invasive transforaminal interbody fusion (MIS-TLIF) are mainly determined by surgeons based on their individual experience. Therefore, it is important to investigate the optimal number and position of cages in MIS-TLIF. Methods: The lumbar model was created based on a 24-year-old volunteer's computed tomography data and then tested using three different cage implantation methods: single transverse cage implantation (model A), single oblique 45° cage implantation (model B), and double vertical cage implantation (model C). A preload of 500 N and a moment of 10 Nm were applied to the models to simulate lumbar motion, and the models' range of motion (ROM), ROM ratio, peak stress of the internal fixation system, and cage were assessed. Results: The ROM ratios of models A, B, and C were significantly reduced by >71% compared with the intact model under all motions. Although there were subtle differences in the ROM ratio for models A, B, and C, the trends were similar. The peak stress of the internal fixation system appeared in model B of 136.05 MPa (right lateral bending), which was 2.07 times that of model A and 1.62 times that of model C under the same condition. Model C had the lowest cage stress, which was superior to that of the single-cage model. Conclusion: In MIS-TLIF, single long-cage transversal implantation is a promising standard implantation method, and double short-cage implantation is recommended for patients with severe osteoporosis.

Feasibility Study of a Novel Magnetic Bone Cement for the Treatment of Bone Metastases.

Bone cement is a crucial material to treat bone metastases defects, and can fill the bone defect and provide mechanical support simultaneously, but the antitumor effect is very limited. Magnetic bone cement not only supports bone metastasis defects but can also achieve magnetic hyperthermia to eliminate tumor cells around the bone defect. However, the physicochemical properties of the bone cement matrix will change if the weight ratio of the magnetic nanoparticles in the cement is too high. We mixed 1 weight percent Zn0.3Fe2.7O4 with good biocompatibility and high heating efficiency into a polymethyl methacrylate matrix to prepare magnetic bone cement, which minimized the affection for physicochemical properties and satisfied the hyperthermia requirement of the alternating magnetic field.

Characterization and Biomechanical Study of a Novel Magnesium Potassium Phosphate Cement.

Magnesium potassium phosphate cement (MKPC) has attracted considerable attention as a bone regeneration material. However, there are only a few reports on its biomechanical properties. To evaluate the biomechanical properties of MKPC, we compared the mechanical parameters of pedicle screws enhanced with either MKPC or polymethyl methacrylate (PMMA) bone cement. The results show that the maximum pull-out force of the pedicle screws was 417.86 ± 55.57 and 444.43 ± 19.89 N after MKPC cement setting for 30 min and 12 h, respectively, which was better than that of the PMMA cement. In fatigue tests, the maximum pull-out force of the MKPC cement group was 435.20 ± 7.96 N, whereas that of the PMMA cement in the control group was 346.80 ± 7.66 N. Furthermore, the structural characterization analysis of the MKPC cement revealed that its microstructure after solidification was an irregular tightly packed crystal, which improved the mechanical strength of the cement. The maximum exothermic temperature of the MKPC reaction was 45.55 ± 1.35 °C, the coagulation time was 7.89 ± 0.37 min, and the compressive strength was 48.29 ± 4.76 MPa, all of which meet the requirements of clinical application. In addition, the MKPC cement did not significantly inhibit cell proliferation or increase apoptosis, thus indicating good biocompatibility. In summary, MKPC exhibited good biomechanical properties, high initial strength, good biocompatibility, and low exothermic reaction temperature, demonstrating an excellent application potential in the field of orthopedics.