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JBMR Plus Apr 2024Achondroplasia (ACH) is a skeletal dysplasia characterized by short-limbed short stature caused by the gain-of-function mutations in the fibroblast growth factor...
Achondroplasia (ACH) is a skeletal dysplasia characterized by short-limbed short stature caused by the gain-of-function mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. Activated FGFR3, which is a negative regulator of bone elongation, impairs the growth of long bones and the spinal arch by inhibiting chondrocyte proliferation and differentiation. Most patients with ACH have spinal canal stenosis in addition to short stature. Meclozine has been found to inhibit FGFR3 via drug repurposing. A 10-d treatment with meclozine promoted long-bone growth in a mouse model of ACH ( mice). This study aimed to evaluate the effects of long-term meclozine administration on promoting bone growth and the spinal canal in mice. Meclozine (2 mg/kg/d) was orally administered to mice for 5 d per wk from the age of 7 d to 56 d. Meclozine (2 mg/kg/d) significantly reduced the rate of death or paralysis and improved the length of the body, cranium, and long bones in male and female mice. Micro-computed tomography analysis revealed that meclozine ameliorated kyphotic deformities and trabecular parameters, including BMD, bone volume/tissue volume, trabecular thickness, and trabecular number at distal femur of mice in both sexes. Histological analyses revealed that the hypertrophic zone in the growth plate was restored in mice following meclozine treatment, suggesting upregulation of endochondral ossification. Skeletal preparations demonstrated that meclozine restored the spinal canal diameter in mice in addition to improving the length of each bone. The 2 mg/kg/d dose of meclozine reduced the rate of spinal paralysis caused by spinal canal stenosis, maintained the growth plate structure, and recovered the bone quality and growth of axial and appendicular skeletons of mice in both sexes. Long-term meclozine administration has the potential to ameliorate spinal paralysis and bone growth in patients with ACH.
PubMed: 38544920
DOI: 10.1093/jbmrpl/ziae018 -
Children (Basel, Switzerland) Mar 2024Joint hypermobility (JH) represents the extreme of the normal range of motion or a condition for a group of genetically determined connective tissue disorders....
CONTEXT
Joint hypermobility (JH) represents the extreme of the normal range of motion or a condition for a group of genetically determined connective tissue disorders. Generalized joint hypermobility (GJH) is suspected when present in all four limbs and the axial skeleton, scored in prepubescent children and adolescents by a Beighton Score (BS) ≥ 6. Parameters are also used to identify GJH in hypermobile Ehlers-Danlos syndrome (hEDS) and hypermobility spectrum disorders (HSDs). The purpose of this study is to characterize children with JH based on the location of variables in the BS ≥ 6 and identify children with JH in the axial skeleton, upper limbs (ULs), and lower limbs (LLs) simultaneously.
METHODS
We analyzed 124 medical records of one- to nine-year-old children with JH by BS.
RESULTS
The characterization of GJH by combinations of the axial skeleton, ULs, and LLs simultaneously totaled 25.7%. BS = 6 and BS = 8 consisted of variables located in ULs and LLs. BS = 7 included the axial skeleton, ULs, and LLs. BS ≥ 6 represents the majority of the sample and predominantly girls.
CONCLUSIONS
BS ≥ 6 represents the majority of the sample and predominantly girls. Most characterized children with GJH present BS = 6 and BS = 8 with variables located only in ULs and LLs, a condition that does not imply the feature is generalized. In children, BS = 7 and BS = 9 characterize GJH by including the axial skeleton, ULs, and LLs. These results draw attention to the implications for defining the diagnosis of hEDS and HSDs.
PubMed: 38539379
DOI: 10.3390/children11030344 -
World Neurosurgery Jun 2024This study aims to introduce the unilateral biplanar screw-rod fixation (UBSF) technique (a hybrid fixation technique: 2 sets of atlantoaxial screws were placed on the...
OBJETIVE
This study aims to introduce the unilateral biplanar screw-rod fixation (UBSF) technique (a hybrid fixation technique: 2 sets of atlantoaxial screws were placed on the same side), which serves as a salvage method for traditional posterior atlantoaxial fixation. To summarize the indications of this technique and to assess its safety, feasibility, and clinical effectiveness in the treatment of odontoid fractures.
METHODS
Patients with odontoid fractures were enrolled according to special criteria. Surgical duration and intraoperative blood loss were documented. Patients were followed up for a minimum of 12 months. X-ray and computerized tomography scans were conducted and reviewed at 1 day, and patients were asked to return for computerized tomography reviews at 3, 6, 9, and 12 months after surgery until fracture union. Recorded and compared the Neck Visual Analog Scale and Neck Disability Index presurgery and at 1 week and 12 months postsurgery.
RESULTS
Between January 2016 and December 2022, our study enrolled 7 patients who were diagnosed with odontoid fractures accompanied by atlantoaxial bone or vascular abnormalities. All 7 patients underwent successful UBSF surgery, and no neurovascular injuries were recorded during surgery. Fracture union was observed in all patients, and the Neck Visual Analog Scale and Neck Disability Index scores improved significantly at 1 week and 12 months postoperative (P < 0.01).
CONCLUSIONS
The UBSF technique has been demonstrated to be safe, feasible, and effective in treating odontoid fractures. In cases where the atlantoaxial bone or vascular structure exhibits abnormalities, it can function as a supplementary or alternative approach to the conventional posterior C1-2 fixation.
Topics: Humans; Odontoid Process; Male; Female; Adult; Middle Aged; Spinal Fractures; Fracture Fixation, Internal; Bone Screws; Atlanto-Axial Joint; Treatment Outcome; Aged; Young Adult
PubMed: 38537785
DOI: 10.1016/j.wneu.2024.03.101 -
American Journal of Veterinary Research Jun 2024The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard...
OBJECTIVE
The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire.
SAMPLES
24 pairs of rabbit femora.
METHODS
After drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated.
RESULTS
The work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types.
CLINICAL RELEVANCE
Mechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit.
Topics: Animals; Rabbits; Femur; Biomechanical Phenomena; Bone Wires; Torsion, Mechanical; Torque
PubMed: 38537376
DOI: 10.2460/ajvr.24.01.0006 -
The Journal of International Medical... Mar 2024To compare the biomechanical stability of a novel, C-shaped nickel-titanium shape memory alloy (SMA) implant (C-clip) with traditional cerclage wiring in the fixation of...
BACKGROUND
To compare the biomechanical stability of a novel, C-shaped nickel-titanium shape memory alloy (SMA) implant (C-clip) with traditional cerclage wiring in the fixation of a Vancouver B1 (VB1) periprosthetic femoral fracture (PFF).
METHODS
In total, 18 synthetic femoral fracture models were constructed to obtain unstable VB1 fracture with an oblique fracture line 8 cm below the lesser trochanter. For each model, the distal portion was repaired using a 10-hole locking plate and four distal bi-cortical screws. The proximal portion was repaired using either three, threaded cerclage wirings or three, novel C-shaped implants. Specimens underwent biomechanical testing using axial compression, torsional and four-point bending tests. Each test was performed on three specimens.
RESULTS
The C-clip was statistically significantly stronger (i.e., stiffer) than cerclage wiring in the three biomechanical tests. For axial compression, medians (ranges) were 39 (39-41) and 35 (35-35) N/mm, for the C-clip and cerclage wiring, respectively. For torsion, medians (ranges) were, 0.44 (0.44-0.45) and 0.30 (0.30-0.33) N/mm for the C-clip and cerclage wiring, respectively. For the four-point bending test, medians (ranges) were 39 (39-41) and 28 (28-31) N/mm; for the C-clip and cerclage wiring, respectively.
CONCLUSION
Results from this small study show that the novel, C-shaped SMA appears to be biomechanically superior to traditional cerclage wiring in terms of stiffness, axial compression, torsion and four-point bending, and may be a valuable alternative in the repair of VB1 PFF. Further research is necessary to support these results.
Topics: Humans; Shape Memory Alloys; Femoral Fractures; Femur; Periprosthetic Fractures; Fracture Fixation, Internal; Bone Plates; Biomechanical Phenomena
PubMed: 38534086
DOI: 10.1177/03000605241240946 -
PloS One 2024This study evaluated the biomechanical performance of narrow-diameter implant (NDI) treatment in atrophic maxillary posterior teeth in aging patients by finite element...
This study evaluated the biomechanical performance of narrow-diameter implant (NDI) treatment in atrophic maxillary posterior teeth in aging patients by finite element analysis. The upper left posterior bone segment with first and second premolar teeth missing obtained from a patient's cone beam computed tomography data was simulated with cortical bone thicknesses of 0.5 and 1.0 mm. Three model groups were analyzed. The Regimen group had NDIs of 3.3 × 10 mm in length with non-splinted crowns. Experimental-1 group had NDIs of 3.0 × 10 mm in length with non-splinted crowns and Experimental-2 group had NDIs of 3.0 × 10 mm in length with splinted crowns. The applied load was 56.9 N in three directions: axial (along the implant axis), oblique at 30° (30° to the bucco-palatal plane compared to the vertical axis of the tooth), and lateral load at 90° (90° in the bucco-palatal plane compared to the vertical axis of the tooth). The results of the von Mises stress on the implant fixture, the elastic strain, and principal value of stress on the crestal marginal bone were analyzed. The axial load direction was comparable in the von Mises stress values in all groups, which indicated it was not necessary to use splinted crowns. The elastic strain values in the axial and oblique directions were within the limits of Frost's mechanostat theory. The principal value of stress in all groups were under the threshold of the compressive stress and tensile strength of cortical bone. In the oblique and lateral directions, the splinted crown showed better results for both the von Mises stress, elastic strain, and principal value of stress than the non-splinted crown. In conclusion, category 2 NDIs can be used in the upper premolar region of aging patients in the case of insufficient bone for category 3 NDI restorations.
Topics: Humans; Finite Element Analysis; Bicuspid; Maxilla; Crowns; Splints; Dental Implants; Dental Stress Analysis; Stress, Mechanical; Biomechanical Phenomena
PubMed: 38527030
DOI: 10.1371/journal.pone.0299816 -
Advanced Science (Weinheim,... Jun 2024Articular cartilage and meniscus transfer and distribute mechanical loads in the knee joint. Degeneration of these connective tissues occurs during the progression of...
Articular cartilage and meniscus transfer and distribute mechanical loads in the knee joint. Degeneration of these connective tissues occurs during the progression of knee osteoarthritis, which affects their composition, microstructure, and mechanical properties. A deeper understanding of disease progression can be obtained by studying them simultaneously. Time-resolved synchrotron-based X-ray phase-contrast tomography (SR-PhC-µCT) allows to capture the tissue dynamics. This proof-of-concept study presents a rheometer setup for simultaneous in situ unconfined compression and SR-PhC-µCT of connective knee tissues. The microstructural response of bovine cartilage (n = 16) and meniscus (n = 4) samples under axial continuously increased strain, or two steps of 15% strain (stress-relaxation) is studied. The chondrocyte distribution in cartilage and the collagen fiber orientation in the meniscus are assessed. Variations in chondrocyte density reveal an increase in the top 40% of the sample during loading, compared to the lower half. Meniscus collagen fibers reorient perpendicular to the loading direction during compression and partially redisperse during relaxation. Radiation damage, image repeatability, and image quality assessments show little to no effects on the results. In conclusion, this approach is highly promising for future studies of human knee tissues to understand their microstructure, mechanical response, and progression in degenerative diseases.
Topics: Animals; Cattle; Synchrotrons; Cartilage, Articular; Proof of Concept Study; Knee Joint; Meniscus; Biomechanical Phenomena; Connective Tissue; X-Ray Microtomography; Osteoarthritis, Knee; Stress, Mechanical
PubMed: 38520713
DOI: 10.1002/advs.202308811 -
Orthopaedic Surgery May 2024The biomechanical characteristics of proximal femoral trabeculae are closely related to the occurrence and treatment of proximal femoral fractures. Therefore, it is of...
OBJECTIVE
The biomechanical characteristics of proximal femoral trabeculae are closely related to the occurrence and treatment of proximal femoral fractures. Therefore, it is of great significance to study its biomechanical effects of cancellous bone in the proximal femur. This study examines the biomechanical effects of the cancellous bone in the proximal femur using a controlled variable method, which provide a foundation for further research into the mechanical properties of the proximal femur.
METHODS
Seventeen proximal femoral specimens were selected to scan by quantitative computed tomography (QCT), and the gray values of nine regions were measure to evaluated bone mineral density (BMD) using Mimics software. Then, an intact femur was fixed simulating unilateral standing position. Vertical compression experiments were then performed again after removing cancellous bone in the femoral head, femoral neck, and intertrochanteric region, and data were recorded. According to the controlled variable method, the femoral head, femoral neck, and intertrochanteric trabeculae were sequentially removed based on the axial loading of the intact femur, and the displacement and strain changes of the femur samples under axial loading were recorded. Gom software was used to measure and record displacement and strain maps of the femoral surface.
RESULTS
There was a statistically significant difference in anteroposterior displacement of cancellous bone destruction in the proximal femur (p < 0.001). Proximal femoral bone mass explained 77.5% of the strength variation, in addition proximal femoral strength was mainly affected by bone mass at the level of the upper outer, lower inner, lower greater trochanter, and lesser trochanter of the femoral head. The normal stress conduction of the proximal femur was destroyed after removing cancellous bone, the stress was concentrated in the femoral head and lateral femoral neck, and the femoral head showed a tendency to subside after destroying cancellous bone.
CONCLUSION
The trabecular removal significantly altered the strain distribution and biomechanical strength of the proximal femur, demonstrating an important role in supporting and transforming bending moment under the vertical load. In addition, the strength of the proximal femur mainly depends on the bone density of the femoral head and intertrochanteric region.
Topics: Humans; Biomechanical Phenomena; Cancellous Bone; Bone Density; Tomography, X-Ray Computed; Female; Male; Femur; Aged; Middle Aged; Femur Head; Cadaver
PubMed: 38520122
DOI: 10.1111/os.14044 -
Neuroradiology Jul 2024We investigated whether the quality of high-resolution computed tomography (CT) images of the temporal bone improves with deep learning reconstruction (DLR) compared... (Comparative Study)
Comparative Study
PURPOSE
We investigated whether the quality of high-resolution computed tomography (CT) images of the temporal bone improves with deep learning reconstruction (DLR) compared with hybrid iterative reconstruction (HIR).
METHODS
This retrospective study enrolled 36 patients (15 men, 21 women; age, 53.9 ± 19.5 years) who had undergone high-resolution CT of the temporal bone. Axial and coronal images were reconstructed using DLR, HIR, and filtered back projection (FBP). In qualitative image analyses, two radiologists independently compared the DLR and HIR images with FBP in terms of depiction of structures, image noise, and overall quality, using a 5-point scale (5 = better than FBP, 1 = poorer than FBP) to evaluate image quality. The other two radiologists placed regions of interest on the tympanic cavity and measured the standard deviation of CT attenuation (i.e., quantitative image noise). Scores from the qualitative and quantitative analyses of the DLR and HIR images were compared using, respectively, the Wilcoxon signed-rank test and the paired t-test.
RESULTS
Qualitative and quantitative image noise was significantly reduced in DLR images compared with HIR images (all comparisons, p ≤ 0.016). Depiction of the otic capsule, auditory ossicles, and tympanic membrane was significantly improved in DLR images compared with HIR images (both readers, p ≤ 0.003). Overall image quality was significantly superior in DLR images compared with HIR images (both readers, p < 0.001).
CONCLUSION
Compared with HIR, DLR provided significantly better-quality high-resolution CT images of the temporal bone.
Topics: Humans; Female; Male; Deep Learning; Temporal Bone; Middle Aged; Retrospective Studies; Tomography, X-Ray Computed; Radiographic Image Interpretation, Computer-Assisted; Adult; Aged
PubMed: 38514472
DOI: 10.1007/s00234-024-03330-1 -
Foot (Edinburgh, Scotland) Jun 2024Talar neck fractures are rare but potentially devastating injuries, with early reduction and rigid fixation essential to facilitate union and prevent avascular necrosis.... (Comparative Study)
Comparative Study
BACKGROUND
Talar neck fractures are rare but potentially devastating injuries, with early reduction and rigid fixation essential to facilitate union and prevent avascular necrosis. Even small degrees of malunion will alter load transmission and subtalar joint kinematics. Changes in fixation techniques have led to dual plating strategies. While locked plating has perceived advantages in porotic bone and comminution, its biomechanical benefits in talar neck fractures have not been shown.
AIM
To compare the strength of locking vs. non-locking plate fixation in comminuted talar neck fractures.
METHOD
Seven pairs of cadaveric tali were randomised to locking or non-locking plate fixation. A standardised model of talar neck fracture with medial comminution was created, and fixation performed. The fixed specimens were mounted onto a motorised testing device, and an axial load applied.
RESULTS
Peak load to failure, deformation at failure, work done to achieve failure, and stiffness of the constructs were measured. No statistically significant difference was found between locking and non-locking constructs for all parameters.
CONCLUSIONS
Both constructs provide similar strength to failure in talar neck fracture fixations. Mean peak load to failure did not exceed the theoretical maximum forces generated of 1.1 kN when weight-bearing. We would advocate caution with early mobilisation in both fixations.
Topics: Humans; Bone Plates; Talus; Fracture Fixation, Internal; Cadaver; Fractures, Comminuted; Biomechanical Phenomena; Male; Female; Middle Aged; Aged; Weight-Bearing; Fractures, Bone
PubMed: 38513373
DOI: 10.1016/j.foot.2024.102084