Biomechanical assessment of different transforaminal lumbar interbody fusion constructs in normal and osteoporotic condition: a finite element analysis.

BACKGROUND CONTEXT: With the aging population, osteoporosis, which leads to poor fusion, has become a common challenge for lumbar surgery. In addition, most people with osteoporosis are elderly individuals with poor surgical tolerance, and poor bone quality can also weaken the stability of internal fixation. PURPOSE: This study compared the fixation strength of the bilateral traditional trajectory screw structure (TT-TT), the bilateral cortical bone trajectory screw structure (CBT-CBT), and the hybrid CBT-TT (CBT screws at the cranial level and TT screws at the caudal level) structure under different bone mineral density conditions. STUDY DESIGN: A finite element (FE) analysis study. METHODS: Above all, we established a healthy adult lumbar spine model. Second, under normal and osteoporotic conditions, three transforaminal lumbar interbody fusion (TLIF) models were established: bilateral traditional trajectory (TT-TT) screw fixation, bilateral cortical bone trajectory (CBT-CBT) screw fixation, and hybrid cortical bone trajectory screw and traditional trajectory screw (CBT-TT) fixation. Finally, a 500-N compression load with a torque of 10 N/m was applied to simulate flexion, extension, lateral bending, and axial rotation. We compared the range of motion (ROM), adjacent disc stress, cage stress, and posterior fixation stress of the different fusion models. RESULTS: Under different bone mineral density conditions, the range of motion of the fusion segment was significantly reduced. Compared to normal bone conditions, the ROM of the L4-L5 segment, the stress of the adjacent intervertebral disc, the surface stress of the cage, and the maximum stress of the posterior fixation system were all increased in osteoporosis. Under most loads, the ROM and surface stress of the cage and the maximum stress of the posterior fixation system of the TT-TT structure are the lowest under normal bone mineral density conditions. However, under osteoporotic conditions, the fixation strength of the CBT-CBT and CBT-TT structures are higher than that of the TT-TT structures under certain load conditions. At the same time, the surface stress of the intervertebral fusion cage and the maximum stress of the posterior fixation system for the two structures are lower than those of the TT-TT structure. CONCLUSION: Under normal bone mineral density conditions, transforaminal lumbar interbody fusion combined with TT-TT fixation provides the best biomechanictability. However, under osteoporotic conditions, CBT-CBT and CBT-TT structures have higher fixed strength compared to TT-TT structures. The hybrid CBT-TT structure exhibits advantages in minimal trauma and fixation strength. Therefore, this seems to be an alternative fixation method for patients with osteoporosis and degenerative spinal diseases. CLINICAL SIGNIFICANCE: This study provides biomechanical support for the clinical application of hybrid CBT-TT structure for osteoporotic patients undergoing TLIF surgery.

Comparison of one-hole split endoscopic discectomy and microendoscopic discectomy in the treatment of lumbar disk herniation: a one-year retrospective cohort study.

BACKGROUND: We aim to compare and assess the surgical parameters and follow-up information of one-hole split endoscopic discectomy (OSE) and microendoscopic discectomy (MED) in the treatment of LDH. METHODS: This study included 154 patients with degenerative lumbar disk disease. Sixty-eight patients underwent OSE and 86 patients MED. The VAS score for lower back and lower limb radiation pain, ODI score, modified MacNab score, estimated blood loss (EBL), length of the incision, amount of C-reactive protein, and recurrence and complication rates were examined as indicators for clinical outcomes and adverse events. RESULTS: After surgery, the VAS and ODI scores in the two groups significantly decreased. On the third day after surgery, the VAS and ODI scores of the OSE group were significantly better than those of the MED group. The VAS and ODI scores preoperatively and at 1 month, 3 months, 6 months, and 12 months following the procedure did not substantially vary between the two groups. There was less EBL and a shorter incision with OSE than with MED. There was no significant difference in the rate of complications between the two groups. CONCLUSION: Compared with MED, OSE is a new alternative option for LDH that can achieve similar and satisfactory clinical outcomes. Furthermore, OSE has many advantages, including less EBL and a smaller incision. Further clinical studies are needed to confirm the effectiveness of OSE.

Metal Ion-Peptide-Intermediated Ligand Transfer for Serum Detection of the Omicron Variant of SARS-Cov-2 in Echinococcosis Patients.

A method is developed to electrochemically induce target-specific covalent capturing of the spike protein of SARS-Cov-2, forming a covalent peptide-protein complex fit for working with such complicated clinical samples. Specifically, peptide-coordinated copper ions can be electrochemically controlled to induce cross-linkage between certain amino acids on the peptide probe and the target protein. Therefore, target specificity can be tuned electrochemically, realizing highly specific targeting of the omicron S protein or broader specificity toward all variants of the virus. Using this method, with electrochemically catalyzed generation of signal-enhancing molecules, the sensitivity and covalent detection allow their application in both serum and fecal samples. These results may point to their possible use in screening new variants of the virus in the near future.

The Role of Smad2 in Transforming Growth Factor ß1-Induced Hypertrophy of Ligamentum Flavum.

BACKGROUND: Hypertrophy of the ligamentum flavum (LF) contributes to the development of spinal stenosis. Smad proteins can mediate the fibrogenesis activity through the transforming growth factor ß1 (TGF-ß1) pathway, but which Smad protein plays a more important role in the hypertrophy process of LF is unclear. METHODS: The LF samples were obtained from 50 patients. After the LF cells (LFCs) were cultured, small interfering ribonucleic acid (siRNA) that target human phosphorylated-Smad2, 3, or 4 (p-Smad2,3,4) genes was transfected into LFCs. Next, proteins from cells were extracted and the protein levels of Smad2, Smad3, and Smad4 were detected by Western blot. The messenger ribonucleic acid level of TGF-ß1 was measured by real-time polymerase chain reaction (PCR). Furthermore, an enzyme-linked immunosorbent assay was performed to test the impact of Smad2 downstream of the TGF-ß1 signaling pathway. RESULTS: Degeneration of the LF was characterized by an increase in disorganized elastic fibers and fibrotic transformation by extracellular collagen deposition. The gene expression analysis of fibrotic genes in LFCs showed that knockdown of phosphorylated-Smad2 by siRNA significantly reduced the protein expression level of TGF-ß1 compared with other groups. The enzyme-linked immunosorbent assay suggested that the protein expression level of Smad2 can influence the downstream events of TGF-ß1 signaling pathway in the LFCs. CONCLUSIONS: Our findings suggest that Smad2 plays a potential role in the pathologic development of hypertrophy of LF. We also found that Smad2 knockdown by Smad-siRNA can influence the TGF-ß1 signaling pathway through decreasing expression of TGF-ß1, tumor necrosis factor α, and nuclear factor κb.

Effect of intensity-modulated radiation therapy on sciatic nerve injury caused by echinococcosis.

Conventional radiotherapy has a good killing effect on femoral echinococcosis. However, the sciatic nerve around the lesion is irreversibly damaged owing to bystander effects. Although intensity-modulated radiation therapy shows great advantages for precise dose distribution into lesions, it is unknown whether intensity-modulated radiation therapy can perfectly protect the surrounding sciatic nerve on the basis of good killing of femoral echinococcosis foci. Therefore, this study comparatively analyzed differences between intensity-modulated radiation therapy and conventional radiotherapy on the basis of safety to peripheral nerves. Pure-breed Meriones meridiani with bilateral femoral echinococcosis were selected as the research object. Intensity-modulated radiation therapy was used to treat left femoral echinococcosis of Meriones meridianus, while conventional radiotherapy was used to treat right femoral echinococcosis of the same Meriones meridianus. The total radiation dose was 40 Gy. To understand whether intensity-modulated radiation therapy and conventional radiotherapy can kill femoral echinococcosis, trypan blue staining was used to detect pathological changes of bone Echinococcus granulosus and protoscolex death after radiotherapy. Additionally, enzyme histochemical staining was utilized to measure acid phosphatase activity in the protoscolex after radiotherapy. One week after radiotherapy, the overall structure of echinococcosis in bilateral femurs of Meriones meridiani treated by intensity-modulated radiation therapy disappeared. There was no significant difference in the mortality rate of protoscoleces of Echinococcus granulosus between the bilateral femurs of Meriones meridiani. Moreover, there was no significant difference in acid phosphatase activity in the protoscolex of Echinococcus granulosus between bilateral femurs. To understand the injury of sciatic nerve surrounding the foci of femoral echinococcosis caused by intensity-modulated radiation therapy and conventional radiotherapy, the ultrastructure of sciatic nerves after radiotherapy was observed by transmission electron microscopy. Additionally, apoptosis of neurons was examined using a terminal-deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and expression of Bcl-2 and Bax in sciatic nerve tissue was detected by immunohistochemical staining and western blot assay. Our results showed that most neurons in the left sciatic nerve of Meriones meridiani with echinococcosis treated by intensity-modulated radiation therapy had reversible injury, and there was no obvious apoptosis. Compared with conventional radiotherapy, the number of apoptotic cells and Bax expression in sciatic nerve treated by intensity-modulated radiation therapy were significantly decreased, while Bcl-2 expression was significantly increased. Our findings suggest that intensity-modulated radiation therapy has the same therapeutic effect on echinococcosis as conventional radiotherapy, and can reduce apoptosis of the sciatic nerve around foci caused by radiotherapy. Experiments were approved by the Animal Ethics Committee of People's Hospital of Xinjiang Uygur Autonomous Region, China (Approval No. 20130301A41) on March 1, 2013.

Effect of unilateral pulsed jet lavage prior to vertebroplasty on the intravertebral pressure and cement distribution.

BACKGROUND: Percutaneous vertebroplasty is the most common treatment for osteoporotic vertebral compression fracture. However, the morbidity of vertebroplasty-related complications, such as cement leakage, remains high. We tested a new technique of unilateral pulsed jet lavage and investigated its effect on the intravertebral pressure and bone cement distribution. METHODS: Thirty lumbar vertebrae (L1-L5) from six cadaver spines were randomly allocated into two groups (with and without irrigation). Prior to vertebroplasty, pulsed jet lavage was performed through one side of the pedicle by using a novel cannula with two concentric conduits to remove the fat and bone marrow of the vertebral bodies in the group with irrigation. The control group was not irrigated. Then, standardized vertebroplasty was performed in the vertebral bodies in both groups. Changes in the intravertebral pressure during injection were recorded. Computed tomography (CT) was performed to observe the cement distribution and extravasations, and the cement mass volume (CMV) was calculated. RESULTS: During cement injection, the average maximum intravertebral pressure of the unirrigated group was higher than that of the irrigated group (4.92 kPa versus 2.22 kPa, P < 0.05). CT scans showed a more homogeneous cement distribution with less CMV (3832 mm3 vs. 4344 mm3, P < 0.05) and less leakage rate (6.7% vs. 46.7%, P < 0.05) in the irrigated group than in the control group. CONCLUSIONS: Unilateral pulsed jet lavage can reduce intravertebral pressure and lower the incidence of cement leakage during vertebroplasty. An enhanced bone cement distribution can also be achieved through this lavage system.

Posterior temporary C1-2 fixation for 3-part fractures of the axis (odontoid dens and Hangman fractures).

Case series study.To report the clinical outcomes of posterior temporary C1-2 fixation for 3-part fracture of the axis (Type II odontoid fracture according to Grauer classification combined with Hangman fracture).The 3-part fracture of the axis is rare and the treatment is controversy.A total of 8 patients with 3-part fracture of the axis were included in this study. X-rays, CT, and MRI prior to surgery were used to evaluate the cervical spine injury. Grauer classification, fracture angulation, and fracture translation were used to evaluate the fracture of dens. The neck disability index (NDI) and range of neck rotary motion were used to assess the neck function.The preoperative fracture angulation and fracture translation were 4.6 ±â€Š1.3° and 2.4 ±â€Š0.6 mm, respectively. The average operation time and blood loss were 109 ±â€Š27 minutes and 49 ±â€Š15 mL. No infection, vascular injuries or neural structure injuries was observed. All patients acquired bone healing at 5.9 ±â€Š2.0 months. The temporary instrumentation was removed at 10.8 ±â€Š1.3 months. The average NDI before and 2 days after removal of instrumentation were 10.1 ±â€Š4.0 and 7.1 ±â€Š3.0, respectively. At 1-year follow-up after instrumentation removal, the NDI was 1.8 ±â€Š0.7, which was much better than immediate NDI after instrumentation removal. The neck rotary motion (left rotation + right rotation) before and 2-day after instrumentation removal were 70.4 ±â€Š6.3° and 119.6 ±â€Š13.1°, respectively. At 1-year follow-up, the average neck rotary motion was 153.1 ±â€Š9.1°, which had significant different with rotary motion 2-day after the removal of temporary instrumentation.With regard to the high fracture fusion rates, low complications, and excellent predictable outcomes in patients treated with posterior temporary C1-2 pedicle screw fixation, the technique may be a suitable choice for 3-part fracture of the axis.

The comparison of clinical outcome of fresh type II odontoid fracture treatment between anterior cannulated screws fixation and posterior instrumentation of C1-2 without fusion: a retrospective cohort study.

BACKGROUND: Recently, the excellent outcomes of temporary fixation of C1-2 without fusion in the treatment of odontoid fracture had been reported. It is still unclear if this technique could achieve the equivalent outcomes as the golden standard technique of anterior screw fixation. The objective of this study is to compare the clinical outcome of two treatments of fresh type II odontoid fracture: anterior cannulated screws fixation (ACSF) versus posterior instrumentation of C1-2 without fusion (PIWF). METHODS: This is a retrospective study. This series included 28 males and 8 females, and the mean age was 41.5 years (range, 22 to 70 years). Eleven patients were treated with ACSF, and 25 patients with PIWF. For PIWF, the implants were removed after fracture union was confirmed at 0.75~1.5 years later. All patients underwent preoperative and serial postoperative clinical examinations at approximately 3 months, 6 months, and annually thereafter. The neck disability index (NDI) was used to assess the neck discomfort caused by the operation. The range of rotary motion was evaluated at each visit. All fractures were reassessed postoperatively with serial X-films and CT scans of the cervical spine at each follow-up visit, to evaluate screw position, fracture alignment, and fusion status. RESULTS: All patients achieved immediate spinal stabilization after surgery, and none experienced neurologic deterioration. The follow-up periods ranged from 24 to 60 months. The average range of neck rotation was dramatically lost in PIWF after fixation (46° and 89° respectively in ACSF and PIWF), and recovered to 83° after the implant was removed. The NDI in PIWF was statistically higher than that in ACSF (5 and 13% respectively in ACSF and PIWF) after the first operation and decreased to 8% 1 year after the secondary operation. The fusion rates were 90.9 and 96% respectively in ACSF and PIWF. Both groups had a case of fracture non-union. CONCLUSIONS: For fresh type II odontoid fractures, high rate of fracture union can be achieved by both ACSF and PIWF. For most fresh type II odontoid fractures, anterior screw fixation was the best option for its simplicity and preservation of normal atlanto-axial rotary function. Posterior instrumentation without fusion could preserve most of the atlanto-axial rotary function and lead to moderate neck discomfort and is also a good alternative if anterior screw fixation is contraindicated.

Three-dimensional conformal intensity-modulated radiation therapy of left femur foci does not damage the sciatic nerve.

During radiotherapy to kill femoral hydatid tapeworms, the sciatic nerve surrounding the focus can be easily damaged by the treatment. Thus, it is very important to evaluate the effects of radiotherapy on the surrounding nervous tissue. In the present study, we used three-dimensional, conformal, intensity-modulated radiation therapy to treat bilateral femoral hydatid disease in Meriones meridiani. The focus of the hydatid disease on the left femur was subjected to radiotherapy (40 Gy) for 14 days, and the right femur received sham irradiation. Hematoxylin-eosin staining, electron microscopy, and terminal deoxynucleotidyl transferase-dUTP nick end labeling assays on the left femurs showed that the left sciatic nerve cell structure was normal, with no obvious apoptosis after radiation. Trypan blue staining demonstrated that the overall protoscolex structure in bone parasitized with Echinococcus granulosus disappeared in the left femur of the animals after treatment. The mortality of the protoscolex was higher in the left side than in the right side. The succinate dehydrogenase activity in the protoscolex in bone parasitized with Echinococcus granulosus was lower in the left femur than in the right femur. These results suggest that three-dimensional conformal intensity-modulated radiation therapy achieves good therapeutic effects on the secondary bone in hydatid disease in Meriones meridiani without damaging the morphology or function of the sciatic nerve.

Spinal cord biological safety of image-guided radiation therapy versus conventional radiation therapy.

Tumor models were simulated in purebred Beagles at the T9-10 levels of the spinal cord and treated with spinal image-guided radiation therapy or conventional radiation therapy with 50 or 70 Gy total radiation. Three months after radiation, neuronal injury at the T9-10 levels was observed, including reversible injury induced by spinal image-guided radiation therapy and apoptosis induced by conventional radiation therapy. The number of apoptotic cells and expression of the proapoptotic protein Fas were significantly reduced, but expression of the anti-apoptotic protein heat shock protein 70 was significantly increased after image-guided radiation therapy compared with the conventional method of the same radiation dose. Moreover, the spinal cord cell apoptotic index positively correlated with the ratio of Fas/heat shock protein 70. These findings indicate that 3 months of radiation therapy can induce a late response in the spinal cord to radiation therapy; image-guided radiation therapy is safer and results in less neuronal injury compared with conventional radiation therapy.