Biomechanical evaluation of a novel anatomical plate for oblique lumbar interbody fusion compared with various fixations: a finite element analysis.

Background: To build a model of an anatomical plate for oblique lumbar interbody fusion (OLIF) surgery based on previous anatomical parameters and verify the biomechanical effect with finite element analysis. Methods: The anatomical plate model was built with AutoCAD and Solidworks. Finite element models of the L2-3 and L4-5 segments were established with computed tomography images from a 46-year-old asymptomatic male individual. Six fixation technique models were created: (I) stand-alone (SA); (II) bilateral pedicle screws (BPS); (III) lateral rod-screw (LRS); (IV) lateral rod-screw plus facet screw (LRSFS); (V) two-screw lateral plate (TSLP); (VI) anatomical plate. The range of motion (ROM), the cage stress, and the instrument stress were calculated under different motion states. Results: In the L2-3 and L4-5 segment models, except for a slightly higher maximum cage stress in the extension state of the TSLP model and the right bending and rotation states of the BPS model, the maximum cage stress in each model was smaller than that of the SA model. In the L2-3 and L4-5 segments, each internal fixation limited the ROM in each motion state. The anatomical plate was more effective in reducing the maximum cage stress and vertebral ROM than the two-screw plate. Three-dimensional finite element analysis did not find a higher risk of construct failure for the anatomical plate model compared with the BPS internal fixation model. Conclusions: Anatomical plates can be considered as supplementary fixations using a single incision and position to improve the stability and rigidity of the construction and reduce the risk of complications.

Biomechanical effects of interbody cage height on adjacent segments in patients with lumbar degeneration: a 3D finite element study.

OBJECTIVE: To investigate the biomechanical effects of interbody cage height on adjacent segments in patients with lumbar degeneration undergoing transforaminal lumbar interbody fusion (TLIF) surgery, so as to provide references for selection of interbody cage. METHODS: The finite element model of normal lower lumbar spine (L3-S1) was built and validated, then constructed three different degenerative segments in L3-L4, and the cages with different height (8, 10, 12, 14 mm) were implanted into L4-L5 disc. All the twelve models were loaded with pure moment of 7.5 N m to produce flexion, extension, lateral bending and axial rotation motions on lumbar spine, and the effects of cage height on range of motion (RoM) and intervertebral pressure in lumbar spine were investigated. RESULTS: The RoM of adjacent segments and the maximum stress of intervertebral discs increased with the increase in cage height, but this trend was not obvious in mild and moderate degeneration groups. After implantation of four different height cages (8, 10, 12, 14 mm), the RoM of L3/L4 segment reached the maximum during extension. The RoM of mild degeneration group was 2.07°, 2.45°, 2.48°, 2.54°, that of moderate degeneration group was 1.79°, 1.97°, 2.05°, 2.05°, and that of severe degeneration group was 1.43°, 1.66°, 1.74°, 1.74°. The stress of L3-L4 intervertebral disc reached the maximum during flexion. The maximum stress of L3-L4 intervertebral disc was 20.16 MPa, 20.28 MPa, 20.31 MPa and 20.33 MPa in the mild group, 20.58 MPa, 20.66 MPa, 20.71 MPa and 20.75 MPa in the moderate group, and 21.27 MPa, 21.40 MPa, 21.50 MPa and 21.60 MPa in the severe group. CONCLUSION: For patients with mild-to-moderate lumbar degenerative disease who need to undergo TLIF surgery, it is recommended that the height of fusion cage should not exceed the original intervertebral space height by 2 mm, while for patients with severe degeneration, a fusion cage close to the original intervertebral height should be selected as far as possible, and the intervertebral space should not be overstretched.

Exosomes from Long Noncoding RNA-Gm37494-ADSCs Repair Spinal Cord Injury via Shifting Microglial M1/M2 Polarization.

Spinal cord injury (SCI) may lead to severe motor and sensory dysfunction, causing high mortality and disability rates. Adipose tissue-derived mesenchymal stem/stromal cells (ADSCs), especially hypoxia-pretreated ADSCs, represent an effective therapy for SCI by promoting the secretion of exosomes (Exos). Here, we investigated the therapeutic efficacy of exosomes secreted by ADSCs under hypoxia (HExos) and explored potential target molecules. We utilized nanoparticle tracking analysis, electron microscopy, qRT-PCR, and western blotting to analyze differences between HExos and Exos groups. The expression of long noncoding RNAs (lncRNAs) was examined by high-throughput sequencing. The therapeutic effects of different Exos treatments were compared in vitro and in an SCI model in vivo. The interaction between lncRNAs, microRNAs, and mRNA was examined by luciferase reporter experiments. We employed enzyme-linked immunosorbent assay and immunofluorescence to measure inflammatory factor expression and microglial polarization. The results showed that HExos was more effective than Exos for repairing SCI by suppressing inflammatory factor expression, promoting functional recovery, and shifting microglia from M1 to M2 polarization. High-throughput sequencing showed that LncGm37494 expression was significantly higher in HExos than Exos, and its upregulation promoted microglial M1/M2 polarization by inhibiting miR-130b-3p and promoting PPARγ expression, as shown by luciferase reporter experiments. Exos from lncGm37494 overexpressing ADSCs showed a similar therapeutic effect than HExos. The results indicated that HExos repair SCI by delivering lncGm37494, advising that lncGm3749 functions importantly in microenvironmental regulation and shows possibility for SCI treatments.

Preparation of antibacterial and osteoconductive 3D-printed PLGA/Cu(I)@ZIF-8 nanocomposite scaffolds for infected bone repair.

BACKGROUND: The repair of large bone defects is a great challenge in clinical practice. In this study, copper-loaded-ZIF-8 nanoparticles and poly (lactide-co-glycolide) (PLGA) were combined to fabricate porous PLGA/Cu(I)@ZIF-8 scaffolds using three-dimensional printing technology for infected bone repair. METHODS: The surface morphology of PLGA/Cu(I)@ZIF-8 scaffolds was investigated by transmission electron microscopy and scanning electron microscopy. The PLGA/Cu(I)@ZIF-8 scaffolds were co-cultured with bacteria to determine their antibacterial properties, and with murine mesenchymal stem cells (MSCs) to explore their biocompatibility and osteoconductive properties. The bioactivity of the PLGA/Cu(I)@ZIF-8 scaffolds was evaluated by incubating in simulated body fluid. RESULTS: The results revealed that the PLGA/Cu(I)@ZIF-8 scaffolds had porosities of 80.04 ± 5.6% and exhibited good mechanical properties. When incubated with H2O2, Cu(I)@ZIF-8 nanoparticles resulted generated reactive oxygen species, which contributed to their antibacterial properties. The mMSCs cultured on the surface of PLGA/Cu(I)@ZIF-8 scaffolds were well-spread and adherent with a high proliferation rate, and staining with alkaline phosphatase and alizarin red was increased compared with the pure PLGA scaffolds. The mineralization assay showed an apatite-rich layer was formed on the surface of PLGA/Cu(I)@ZIF-8 scaffolds, while there was hardly any apatite on the surface of the PLGA scaffolds. Additionally, in vitro, Staphylococcus aureus cultured on the PLGA/Cu(I)@ZIF-8 scaffolds were almost all dead, while in vivo inflammatory cell infiltration and bacteria numbers were dramatically reduced in infected rats implanted with PLGA/Cu@ZIF-8 scaffolds. CONCLUSION: All these findings demonstrate that PLGA/Cu(I)@ZIF-8 scaffolds possess excellent antibacterial and osteoconductive properties, as well as good biocompatibility and high bioactivity. This study suggests that the PLGA/Cu(I)@ZIF-8 scaffolds could be used as a promising biomaterial for bone tissue engineering, especially for infected bone repair.

Analysis of radiological parameters associated with decreased fractional anisotropy values on diffusion tensor imaging in patients with lumbar spinal stenosis.

PURPOSE: Previous studies have indicated that decreased fractional anisotropy (FA) values on diffusion tensor imaging (DTI) are well correlated with the symptoms of nerve root compression. The aim of our study is to determine primary radiological parameters associated with decreased FA values in patients with lumbar spinal stenosis involving single L5 nerve root. METHODS: Patients confirmed with single L5 nerve root compression by transforaminal nerve root blocks were included in this study. FA values of L5 nerve roots on both symptomatic and asymptomatic side were obtained. Conventional radiological parameters, such as disc height, degenerative scoliosis, dural sac cross-sectional area (DSCSA), foraminal height (FH), hypertrophic facet joint degeneration (HFJD), sagittal rotation (SR), sedimentation sign, sagittal translation and traction spur were measured. Correlation and regression analyses were performed between the radiological parameters and FA values of the symptomatic L5 nerve roots. A predictive regression equation was established. RESULTS: Twenty-one patients were included in this study. FA values were significantly lower at the symptomatic side comparing to the asymptomatic side (0.263 ± 0.069 vs. 0.334 ± 0.080, P = 0.038). DSCSA, FH, HFJD, and SR were significantly correlated with the decreased FA values, with r = 0.518, 0.443, 0.472 and - 0.910, respectively (P < 0.05). DSCSA and SR were found to be the primary radiological parameters related to the decreased FA values, and the regression equation is FA = - 0.012 × SR + 0.002 × DSCSA. CONCLUSIONS: DSCSA and SR were primary contributors to decreased FA values in LSS patients involving single L5 nerve root, indicating that central canal decompression and segmental stability should be the first considerations in preoperative planning of these patients. These slides can be retrieved under Electronic Supplementary Material.

Asymmetry between the superior and inferior endplates is a risk factor for lumbar disc degeneration.

Endplate pathology plays an important role in the development of lumbar disc degeneration. Previous research paid little attention to differences between the superior and inferior endplates as a possible risk factor for disc degeneration. The purpose of this study was to test the hypothesis that asymmetry between the superior and inferior endplates is a risk factor for the development of lumbar disc degeneration. A total of 134 patients with lumbar disc herniation (LDH) and 100 healthy adults ("Controls") underwent magnetic resonance imaging scans. Each disc was categorized as non-degenerated (Pfirrmann grades I-II) or degenerated (Pfirrmann grades III-V) and get the following three groups: "Degenerated LDH" discs (n = 145), "Non-degenerated LDH" discs (n = 525) and "Non-degenerated Control" discs (n = 500). On mid-sagittal image, the lumbar endplate morphology could be categorized into three types: Flat, concave, and irregular. Superior and inferior endplates of a given disc were "symmetric" if both were of the same type, and "asymmetric" if they were of different types. The proportion of asymmetric endplates at L4-5 was higher in the "Degenerated LDH" discs group (47%) than in the "Non-degenerated LDH" discs group (21%) or "Non-degenerated Control" discs group (7%) (p < 0.05). At L5-S1 the proportions were 73%, 55%, and 38% (p < 0.05). Asymmetry of superior and inferior endplates in the mid-sagittal plane is a risk factor for lumbar disc degeneration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2469-2475, 2018.

Feasibility of Screw Placement in the Occipital Condyle of Chinese Patients for Occipitocervical Arthrodesis: A Cadaveric Study.

AIM: The feasibility of computed tomography (CT) and two-dimensional (2D) reconstruction-guided screw placement in the occipital condyle (OC) of Chinese patients was investigated. MATERIAL AND METHODS: Twenty (40 OCs) fresh cadaveric specimens with intact superior cervical spine and occipital bones were placed in the prone position. Simulated screw placement was achieved by placing 4.0 mm diameter virtual screws with the help of the 2D reconstruction CT scan image technology. Maximal screw length, angulation in the sagittal and transverse planes, and medial and cranial base OC entry points were determined and recorded. Actual screw placement was achieved by similar placement; actual position and angulation were determined by postoperative CT scanning. RESULTS: Screws were successfully inserted in 36 of 40 (90%) OCs. Four ruptures of the medial OC wall were on the left side. Actual screw placement did not damage the hypoglossal canal, and no screws pierced the medial or lateral OC walls. Females displayed significantly smaller left and right maximum screw lengths than males (p < 0.05); no other significant gender differences were noted. CONCLUSION: The results can feasibly accommodate 4-mm OC screws for OA treatment. As in other populations, OC shape and size is smaller in females and varies in Chinese individuals, necessitating individualized imaging for good outcomes.

Abnormal flexor carpi radialis H-reflex as a specific indicator of C7 as compared with C6 radiculopathy.

OBJECTIVE: The H-reflex of the flexor carpi radialis (FCR H-reflex) has not been commonly used for the diagnosis of cervical radiculopathy when compared with the routinely tested soleus H-reflex. Although both S1 and S2 roots innervate the soleus, the H-reflex is selectively related to S1 nerve root function clinically. Flexor carpi radialis is also innervated by two nerve roots which are C6 and C7. Although they are among the most common roots involved in cervical radiculopathy, few studies reported if the attenuation of the FCR H-reflex is caused by lesions affecting C7 or C6 nerve roots, or both. We aimed to identify whether an abnormal FCR H-reflex was attributed to the C7 or C6 nerve root lesion, or both. The sensitivities of needle electromyography, FCR H-reflex, and provocative tests in unilateral C7 or C6 radiculopathy were also compared in this study. METHODS: A concentric needle electrode recorded bilateral FCR H-reflexes in 41 normal subjects (control group), 51 patients with C7 radiculopathy, and 54 patients with C6 radiculopathy. Clinical, radiological, and surgical approaches identified the precise single cervical nerve root involved in all patient groups. The H-reflex and M-wave latencies were measured and compared bilaterally. Abnormal FCR H-reflex was defined as the absence of the H-reflex or a side-to-side difference over 1.5 milliseconds which was based on the normal side-to-side difference of the H-reflex latency of 16.9 milliseconds (SD = 1.7 milliseconds) from the control group. We also determined standard median and ulnar conduction and needle electromyography. The provocative tests included bilateral determination of the Shoulder Abduction and Spurling's tests in all radiculopathy group patients. RESULTS: Abnormal FCR H-reflexes were recorded in 45 (88.2%) of C7 radiculopathy group patients, and 2 (3.7%) of C6 radiculopathy group patients (P < 0.05). Needle electromyography was abnormal in 41 (80.4%) of C7 radiculopathy patients and 43 (79.6%) of C6 radiculopathy patients. Provocative tests were positive in 15 (29.4%) of C7 radiculopathy patients and 25 (46.3%) of C6 radiculopathy patients. CONCLUSIONS: Flexor carpi radialis H-Reflex provides a sensitive assessment of evaluating the C7 spinal reflex pathway. Clinically, a combination of the FCR H-reflex with needle electromyography may yield the highest level of diagnostic information for evaluating clinical cases of C7 radiculopathy.

Magnetic resonance neurography in analysis of operative safety of transforaminal lumbar interbody fusion in Chinese subjects.

OBJECTIVE: To measure relevant anatomical variables of lumbosacral nerve root and adjacent structures by magnetic resonance neurography (MRN) and analyze operative safety of transforaminal lumbar interbody fusion (TLIF) in Chinese subjects. METHODS: Twelve normal healthy volunteers (six men, six women) underwent MRN of lumbosacral nerve roots at 3.0 T. Three-dimensional imaging was reconstructed with Osirix software and the following anatomic variables measured: (i) distance between nerve root and upper pedicle; (ii) distance between nerve root and lower pedicle; (iii) angle between nerve root and sagittal plane; (iv) distance between upper and lower nerve roots; and (v) distance between upper and lower pedicles. RESULTS: Good images of the L(1)-L(5) nerve roots were obtained by MRN technology in all 12 volunteers. The distance between nerve root and upper pedicle and the angle between nerve roots and the sagittal plane gradually diminished from L(1) to L(5). However, there were no significant variations in the distance between nerve root and lower pedicle or between upper and lower pedicles. From L(1 -2) to L(4 -5), the distances between upper and lower pedicles, which are closely related to the operating space for TLIF in Chinese men and women, were less than 10 mm in most subjects and were significantly smaller in women than in men. The variables did not differ significantly between the left and right sides of the same segment. CONCLUSION: Based on the above anatomical study and measurement analysis, we believe that TLIF puts the upper nerve root at risk in some Chinese patients. However, this conclusion requires confirmation by anatomical study of large samples and clinical validation.

Osteoinductive activity of ErhBMP-2 after anterior cervical diskectomy and fusion with a ß-TCP interbody cage in a goat model.

Bone morphogenetic protein (BMP)-2 induces bone and cartilage tissue formation. Large amounts of BMP-2 are difficult to purify or to produce in vitro using eukaryotic cells. The goal of the present study was to assess the clinical use of Escherichia coli-derived recombinant human BMP-2 (ErhBMP-2) on bone fusion after cervical and lumbar spine surgery in a goat model, compared with the standard autogenous iliac bone grafting. Thirty-six goats were randomized to 3 groups: (A) autogenous iliac bone grafting, (B) cervical interbody fusion cage containing ß-tricalcium phosphate (ß-TCP), or (C) cervical interbody fusion cage containing ß-TCP+ErhBMP-2 (2.5 mg). Cervical bone repair was evaluated using radiographs and computed tomography scans at 0, 3, and 6 months. Histological analyses were performed on cervical samples. Two goats died from infection. The differences in intervertebral height among the groups were not significant 3 months postoperatively but became significant after 6 months between groups A vs B and C (P=.04); there was no difference between groups B and C at 6 months. Adding ErhBMP-2 significantly increased cervical fusion at 6 months (P=.04). Histological examinations showed that ß-TCP+ErhBMP-2 increased new bone area, material degradation rate, and depth of tissue penetration and decreased residual material area, all in a time-dependent manner. Escherichia coli-derived rhBMP-2 combined with an enhanced fusion cage containing ß-TCP induced bone formation in a goat model. Furthermore, its ability to promote bone fusion was similar to autogenous iliac bone grafting.

Effects of TGF-ß1 and IL-1ß on expression of ADAMTS enzymes and TIMP-3 in human intervertebral disc degeneration.

The aim of this study was to investigate the effects of transforming growth factor-ß1 (TGF-ß1) and interleukin-1ß (IL-1ß) on the expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) enzymes and their inhibitor, tissue inhibitor of metalloproteinase 3 (TIMP-3), in human intervertebral disc (IVD) degeneration. Cells from patients with IVD degeneration were cultured with Dulbecco's modified Eagle's medium with Ham's F12 nutrient mixture (DMEM/F12) medium at 37°C in a 5% CO2 incubator. Cell proliferation was measured by cell counting kit-8 assays with varying concentrations of TGF-ß1 and IL-1ß in a time-response experiment. The mRNA and protein expression levels of ADAMTS-4, ADAMTS-5 and TIMP-3 were detected with qPCR and western blot analysis, respectively. The present study demonstrated that TGF-ß1 promoted nucleus pulposus (NP) cell proliferation, decreased the expression of ADAMTS-4 and -5 and increased the expression of TIMP-3. By contrast, the IL-1ß treatment inhibited NP cell proliferation and significantly increased the expression of ADAMTS-4 and -5. However, IL-1ß appeared to have no marked effect on the expression of TIMP-3. This study suggests that TGF-ß1 and IL-1ß are involved in the synthesis and degradation of the extracellular matrix and may act as potential therapeutic targets for the prevention or reversal of IVD degeneration.

Multifocal osteolytic lesions within lumbar spine in a middle-aged Chinese woman: a benign metastasizing leiomyoma?

STUDY DESIGN: Case report. OBJECTIVE: To describe a case presented as osteolytic lesions involving 2 inconsecutive lumbar, which was pathologically proved to be of smooth muscular origin. SUMMARY OF BACKGROUND DATA: Smooth muscle tumor of uncertain malignant potential (STUMP) could be diagnosed when the neoplasm showed some malignant behavior, whereas its histologic image revealed very low malignance. A 47-year-old woman presented with low back pain and numbness of the left lower extremity attributable to osteolytic lesions in the second and fourth lumbar vertebral bodies, which was subsequently diagnosed as STUMP. A benign metastasizing leiomyoma was highly suspected. METHODS: Clinical, pathologic, and radiologic characters of the patient with STUMP confined within the lumbar spine were retrospectively reviewed. A mini review was also conducted. RESULTS: We describe the first spine-confined case of STUMP. CONCLUSION: Significant new information in the growing literature of this rare and newly identified diagnosis has addressed the need for orthopedists to consider the STUMP diagnosis.