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BMC Musculoskeletal Disorders May 2024The emerging of the C2 isthmus screw fixation technique is gaining popularity in the setting of atlantoaxial dislocation or other conditions requiring fixation of C2....
BACKGROUND
The emerging of the C2 isthmus screw fixation technique is gaining popularity in the setting of atlantoaxial dislocation or other conditions requiring fixation of C2. However, the biomechanical stability of this fixation is poorly understood.
PURPOSE
To compare and elucidate the biomechanical stability of C2 pedicle screw (C2PS), C2 isthmus screw (C2IS) and C2 short isthmus screw (C2SIS) fixation techniques in atlantoaxial dislocation (AAD).
METHOD
A three-dimensional finite element model (FEM) from occiput to C3 was established and validated from a healthy male volunteer. Three FEMs, C1 pedicle screw (PS)-C2PS, C1PS-C2IS, C1PS-C2SIS were also constructed. The range of motion (ROM) and the maximum von Mises stress under flexion, extension, lateral bending and axial rotation loading were analyzed and compared. The pullout strength of the three fixations for C2 was also evaluated.
RESULT
C1PS-C2IS model showed the greatest decrease in ROM with flexion, extension, lateral bending and axial rotation. C1PS-C2PS model showed the least ROM reduction under all loading conditions than both C2IS and C2SIS. The C1PS-C2PS model had the largest von Mises stress on the screw under all directions followed by C1PS-C2SIS, and lastly the C1PS-C2IS. Under axial rotation and lateral bending loading, the three models showed the maximum and minimum von Mises stress on the screw respectively. The stress of the three models was mainly located in the connection of the screw and rod. Overall, the maximum screw pullout strength for C2PS, C2IS and C2SIS were 729.41N, 816.62N, 640.54N respectively.
CONCLUSION
In patients with atlantoaxial dislocations, the C2IS fixation provided comparable stability, with no significant stress concentration. Furthermore, the C2IS had sufficient pullout strength when compared with C2PS and C2SIS. C2 isthmus screw fixation may be a biomechanically favourable option in cases with AAD. However, future clinical trials are necessary for the evaluation of the clinical outcomes of this technique.
Topics: Humans; Finite Element Analysis; Atlanto-Axial Joint; Male; Biomechanical Phenomena; Joint Dislocations; Range of Motion, Articular; Adult; Pedicle Screws; Bone Screws; Spinal Fusion
PubMed: 38811940
DOI: 10.1186/s12891-024-07470-6 -
Injury Jul 2024Traumatologists are unable to predict hip instability based on CT scans and standard radiographs in posterior wall (PW) fractures comprising <50-60 % of the wall,...
BACKGROUND
Traumatologists are unable to predict hip instability based on CT scans and standard radiographs in posterior wall (PW) fractures comprising <50-60 % of the wall, necessitating an examination under anesthesia (EUA). Risk factors for instability have not been clarified, but acetabular dysplasia has been theorized as a potential etiology. Unfortunately, dysplasia is difficult to evaluate in the traumatic setting. The purpose of this study was to compare acetabular morphology between unstable and stable fractures with a novel method to detect dysplasia.
METHODS
Patients ≥ 18 years old with a PW fracture that underwent an EUA from 2013 to 2023 were retrospectively identified. For our experimental measurements, the axial distances on CT between the acetabular dome, lateral acetabular opening, and femoral head vertex were recorded. Acetabular geometry was quantified at these levels. Conventional dysplasia metrics (e.g., Tonnis angle) were obtained. Variables were compared between stable and unstable fractures.
RESULTS
58 patients met inclusion criteria with 42 stable versus 16 unstable fractures. Unstable fractures had higher distances between the acetabular dome and femoral head vertex (p > 0.05). They had more cranial fracture exit points (p = 0.0015), lower femoral head coverage (p = 0.0102), and lower posterior acetabular sector angles (p = 0.0281). No other differences in acetabular geometry, demographics, injury characteristics, or other markers of dysplasia were identified.
CONCLUSIONS
Unstable hips demonstrated a more recessed acetabular dome when compared to stable hips. Posterior acetabular femoral head coverage and cranial fracture exit point may be related to hip instability. A larger sample size is needed to validate these findings.
Topics: Humans; Acetabulum; Male; Female; Retrospective Studies; Tomography, X-Ray Computed; Middle Aged; Adult; Joint Instability; Hip Dislocation; Hip Fractures; Aged; Risk Factors; Femur Head
PubMed: 38810571
DOI: 10.1016/j.injury.2024.111601 -
Scientific Reports May 2024Stress shielding and aseptic loosening are complications of short stem total hip arthroplasty, which may lead to hardware failure. Stems with increased porosity toward...
Stress shielding and aseptic loosening are complications of short stem total hip arthroplasty, which may lead to hardware failure. Stems with increased porosity toward the distal end were discovered to be effective in reducing stress shielding, however, there is a lack of research on optimized porous distribution in stem's coating. This study aimed to optimize the distribution of the coefficient of friction of a metaphyseal femoral stem, aiming for reducing stress shielding in the proximal area. A finite element analysis model of an implanted, titanium alloy short-tapered wedge stem featuring a porous coating made of titanium was designed to simulate a static structural analysis of the femoral stem's behavior under axial loading in Analysis System Mechanical Software. For computational feasibility, 500 combinations of coefficients of friction were randomly sampled. Increased strains in proximal femur were found in 8.4% of the models, which had decreased coefficients of friction in middle medial areas of porous coating and increased in lateral proximal and lateral and medial distal areas. This study reported the importance of the interface between bone and middle medial and distal lateral areas of the porous coating in influencing the biomechanical behavior of the proximal femur, and potentially reducing stress shielding.
Topics: Humans; Friction; Femur; Hip Prosthesis; Porosity; Arthroplasty, Replacement, Hip; Finite Element Analysis; Titanium; Stress, Mechanical; Prosthesis Design; Coated Materials, Biocompatible; Biomechanical Phenomena; Alloys
PubMed: 38806607
DOI: 10.1038/s41598-024-63077-w -
Heliyon May 2024The world has been battling climate change which is caused by an excessive amount of carbon dioxide in the atmosphere. Carbon sequestration in geological sinks was...
The world has been battling climate change which is caused by an excessive amount of carbon dioxide in the atmosphere. Carbon sequestration in geological sinks was identified as one of the major methods to curb and reduce the amount of carbon dioxide in the atmosphere. The carbon dioxide stored in the geological formations must not escape back into the atmosphere. Characterisation of potential reservoirs for geological sequestration is pertinent for injectivity, capacity, and most importantly containment of carbon dioxide. The cap rock is one of the most important factors determining carbon sequestration success. This study focuses on the preliminary characterisation of the caprocks for evaluating potential subsurface storage of carbon dioxide based on their petrophysical characteristics. X-ray Diffraction and X-ray Fluorescence provided the mineralogical composition and geochemical data of the cap rocks while Scanning Electron Microscopy-EDS was used to identify the qualitative information on the micromorphological textural structure of the cap rocks in the Niger Delta. Conventional Triaxial experiments were used to determine the elastic and geo-mechanical strength of the caprocks. It was identified that the grain skeleton of caprocks in the region is predominated by Quartz, Albite, and Muscovite. The ratio of the tectosilicate and phyllosilicate minerals indicates that the cap rocks are silicate shale. The peak strength of the caprocks ranged from 48.85 to 80.50 MPa and are classified as strong rocks. The cap rocks showed a quasi-elastic behaviour after being subjected to compressive axial force. The elastic modulus of the caprocks was also observed. The characteristics exhibited by the shale caprock at the rock matrix level are highly favourable for sealing carbon dioxide and hence indicate capability for use in carbon sequestration.
PubMed: 38803952
DOI: 10.1016/j.heliyon.2024.e31206 -
Scientific Reports May 2024Distal femoral osteotomy (DFO) is performed alone or with high tibial osteotomy (HTO) for patients with osteoarthritis and distal femur deformities. DFO is technically...
Distal femoral osteotomy (DFO) is performed alone or with high tibial osteotomy (HTO) for patients with osteoarthritis and distal femur deformities. DFO is technically demanding, particularly when creating an anterior flange. Herein, we examined the morphological characteristics of the distal femur based on the cortical shape as a surgical reference for biplanar DFO. Computed tomography images of 50 valgus and 50 varus knees of patients who underwent biplanar DFO or total knee arthroplasty were analyzed. Axial slices at the initial level of the transverse osteotomy in the DFO and slices 10 mm proximal and 10 mm distal to that level were selected. The medial and lateral cortical angles and heights (MCLA, LCLA, MCH, and LCH) were measured on axial slices. Statistical comparisons were performed between the medial and lateral cortices and valgus and varus knees. MCLA and MCH were significantly smaller and lower, respectively, than LCLA and LCH (P < 0.01). The MCLA and MCH of varus knees were significantly smaller and lower, respectively, than those of valgus knees (P < 0.01). Surgeons should carefully observe morphological differences in the distal femur cortex, distinguishing between medial and lateral knees and varus and valgus knees during the creation of the anterior flange in the DFO.
Topics: Humans; Osteotomy; Femur; Female; Male; Middle Aged; Aged; Tomography, X-Ray Computed; Knee Joint; Osteoarthritis, Knee; Arthroplasty, Replacement, Knee; Tibia; Adult
PubMed: 38802483
DOI: 10.1038/s41598-024-62988-y -
Frontiers in Immunology 2024levels are elevated in the blood and synovial fluid of patients with inflammatory arthritis. can be produced by Th17 cells and locally within joints by tissue-resident...
OBJECTIVES
levels are elevated in the blood and synovial fluid of patients with inflammatory arthritis. can be produced by Th17 cells and locally within joints by tissue-resident cells. induces osteoblast mineralization . As osteoproliferation and Th17 cells are important factors in the pathogenesis of axial spondyloarthritis (axSpA), we aimed to clarify the cellular sources of in spondyloarthritis.
METHODS
Serum, peripheral blood mononuclear cells ( = 15-35) and synovial tissue ( = 3-9) of adult patients with axSpA, psoriatic arthritis (PsA) and rheumatoid arthritis (RA) and healthy controls (HCs, = 5) were evaluated by ELISA, flow cytometry including PrimeFlow assay, immunohistochemistry and immunofluorescence and quantitative PCR.
RESULTS
Synovial tissue of axSpA patients shows significantly more -positive cells than that of HCs ( < 0.01), but numbers are also elevated in PsA and RA patients. Immunofluorescence shows co-localization of with CD68, but not with CD3, SMA, CD163, cadherin-11, or CD90. is elevated in the serum of RA and PsA (but not axSpA) patients compared with HCs ( < 0.001 and < 0.01). However, peripheral blood CD4 T cells from axSpA and PsA patients show higher positivity for in the PrimeFlow assay compared with HCs. CD4 memory T cells from axSpA patients produce more under Th17-favoring conditions (IL-1β and IL-23) than cells from PsA and RA patients or HCs.
CONCLUSION
production is increased in the synovial tissue of SpA and can be localized to CD68 macrophage-like synoviocytes, whereas circulating Th17 cells are only modestly enriched. Considering the osteoproliferative properties of , this offers new therapeutic options independent of Th17 pathways.
Topics: Humans; Arthritis, Psoriatic; Synoviocytes; Male; Adult; Female; Antigens, CD; Interleukins; Middle Aged; Antigens, Differentiation, Myelomonocytic; Axial Spondyloarthritis; Th17 Cells; Synovial Membrane; Joints; Arthritis, Rheumatoid
PubMed: 38799447
DOI: 10.3389/fimmu.2024.1355824 -
International Journal of Surgery Case... Jul 2024LCH in adults is rarely encountered, with the preference in children and axial skeleton as predilection site. Limited understanding of adult LCH causes frequent...
INTRODUCTION AND IMPORTANCE
LCH in adults is rarely encountered, with the preference in children and axial skeleton as predilection site. Limited understanding of adult LCH causes frequent misdiagnosis, as our experience in an adult case of LCH threw off our differential diagnosis.
CASE PRESENTATION
A 21-year-old male was referred to our hospital due to pain in his right shoulder. Plain radiograph and MRI showed a solitary well-marginated lytic lesion on the distal third of the clavicle. Together with a clear history and physical exam, the benign bone cyst was suspected and we performed an open biopsy simultaneously with curettage followed by internal fixation using a bone graft. Pathology and immunohistochemistry dismissed our suspicion and confirmed LCH as the main diagnosis. At six months post-surgery, no signs of recurrence were seen on the fixated site nor complained by the patient.
DISCUSSION
Diagnosing LCH involves considering imaging appearances and patient demographics as initial clues. However, confirming the diagnosis requires a biopsy with proven CD1 expression. Currently, the majority of studies recommend confirming the diagnosis before initiating therapy. This precaution is necessary due to the unclear pathophysiology of LCH, which complicates the implementation of specific therapies. Based on benign features of skeletal lesions found from imaging, invasive treatment before biopsy confirmation still gave a satisfactory outcome despite not being in line with the current recommendation.
CONCLUSION
Excisional biopsy and curettage in solitary LCH yield satisfactory outcomes. However, further studies are needed with larger sample sizes and interventional designs.
PubMed: 38796936
DOI: 10.1016/j.ijscr.2024.109801 -
Spinal Cord Series and Cases May 2024Down syndrome is the most common chromosomal abnormality associated with intellectual impairments. Unexpected deaths are common with this disease. There are certain...
INTRODUCTION
Down syndrome is the most common chromosomal abnormality associated with intellectual impairments. Unexpected deaths are common with this disease. There are certain difficulties in clarifying the cause of death because the manifestations may be quite diverse and involve many organ systems. Atlantoaxial subluxation is a dangerous complication of Down syndrome, as it may lead to cervical cord-medullary compression.
CASE PRESENTATION
Herein, we present a case of Down syndrome in a patient who completely recovered from cardiac arrest due to atlantoaxial subluxation. The neck was immobilized during post-cardiac arrest care, and the patient underwent surgery after 14 days. The patient could walk independently and was discharged 3 months later. At the last follow-up 5 years after surgery, the patient's general condition was good.
DISCUSSION
Physicians should be aware that atlantoaxial instability can cause cardiac arrest in patients with genetic syndromes.
Topics: Humans; Down Syndrome; Atlanto-Axial Joint; Heart Arrest; Joint Dislocations; Male
PubMed: 38796439
DOI: 10.1038/s41394-024-00649-y -
Journal of Clinical Medicine May 2024Axial spondyloarthropathy(AS) is a chronic inflammatory disease primarily affecting the axial skeleton, often characterized by sacroiliitis. While pulmonary embolism...
Axial spondyloarthropathy(AS) is a chronic inflammatory disease primarily affecting the axial skeleton, often characterized by sacroiliitis. While pulmonary embolism (PE), a potentially lethal condition, has been linked to several autoimmune diseases, limited data exist regarding PE risk among patients with AS. This retrospective cohort study utilized the Clalit Healthcare Services (CHS) database, including 5825 patients with AS and 28,356 matched controls. Follow-up began at the date of first AS diagnosis for patients and at the matched patient's diagnosis date for controls and continued until PE diagnosis, death, or study end date. Prevalence of PE before AS diagnosis in patients compared to controls was 0.4% vs. 0.2% ( < 0.01). The incidence rate of PE was 11.6 per 10,000 person-years for patients with AS and 6.8 per 10,000 person-years for controls. The adjusted hazard ratio (HR) for PE in patients with AS was 1.70 ( < 0.001). Subgroup analysis demonstrated excess risk for PE in patients with AS regardless of gender and age, with variations among AS treatment categories. Our findings highlight a significant association between AS and PE, indicating an increased risk in patients with AS independent of age and sex and suggests a subclinical level of inflammation. Preliminary results suggest a protective role of immunosuppressing drugs. Further research into the impact of treatment strategies should be conducted and could inform clinical management and reduce the life-threatening risk of PE in Patients with AS.
PubMed: 38792334
DOI: 10.3390/jcm13102790 -
Medical Engineering & Physics Jun 2024Despite the fact that lower back pain caused by degenerative lumbar spine pathologies seriously affects the quality of life, however, there is a paucity of research on...
Despite the fact that lower back pain caused by degenerative lumbar spine pathologies seriously affects the quality of life, however, there is a paucity of research on the biomechanical properties of different auxiliary fixation systems for its primary treatment (oblique lumbar interbody fusion) under vibratory environments. In order to study the effects of different fixation systems of OLIF surgery on the vibration characteristics of the human lumbar spine under whole-body vibration (WBV), a finite element (FE) model of OLIF surgery with five different fixation systems was established by modifying a previously established model of the normal lumbar spine (L1-S1). In this study, a compressive follower load of 500 N and a sinusoidal axial vertical load of ±40 N at the frequency of 5 Hz with a duration of 0.6 s was applied. The results showed that the bilateral pedicle screw fixation model had the highest resistance to cage subsidence and maintenance of disc height under WBV. In contrast, the lateral plate fixation model exerted very high stresses on important tissues, which would be detrimental to the patient's late recovery and reduction of complications. Therefore, this study suggests that drivers and related practitioners who are often in vibrating environments should have bilateral pedicle screws for OLIF surgery, and side plates are not recommended to be used as a separate immobilization system. Additionally, the lateral plate is not recommended to be used as a separate fixation system.
Topics: Vibration; Spinal Fusion; Lumbar Vertebrae; Finite Element Analysis; Humans; Biomechanical Phenomena; Pedicle Screws
PubMed: 38789212
DOI: 10.1016/j.medengphy.2024.104169