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Objective:To optimize the topological design of locking plate for distal radial fracture so that the internal fixation stiffness can be customized.Methods:Models of both the distal radial fracture and the conventional locking plate fixation were constructed using software for three-dimensional modeling and computer-aided design. Based on the data from our previous finite element analysis, a decrease of 33.33% in axial stiffness but retention of more than 90.00% in torsional stiffness were defined as the optimization limits. The conventional plate was redesigned by way of topological optimization iterations. Finite element analysis was done to compare stiffness and interfragmentary strain (IFS) between the new optimized design and conventional design of the locking plate under both compressive and torsional loads.Results:The axial stiffness of the optimized plate was 636.5 N/mm with a downgrading magnitude of 19.7% which was close to the given limit; the torsional stiffness was 634.12 Nmm/° with a downgrading magnitude of 8.8% which remained under the given limit. In the optimized design, a more significant increase was observed in axial IFS than that in shear IFS, leading to a similar effect as the stiffness regulation did.Conclusion:The optimized design of locking plate for distal radial fracture can provide a reliable solution for customized regulation of the internal fixation stiffness.
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Objective To explore the dynamic characteristics of the thoracolumbar osteoporotic vertebral bodies under free state. Methods Based on CT data from the thoracic and lumbar vertebral body of a healthy female volunteer, model materialization and intervertebral disc tissue reconstruction were realized by using the computerized processing software. The finite element models of normal thoracolumbar vertebral body and thoracolumbar osteoporotic vertebral body were established in ABAQUS 6.14 to perform modal analysis. Results Compared with the normal model, the osteoporosis model had a lower natural frequency and a lager amplitude. As the vibration frequency increased, the model vibration type changed from uniaxial and unidirectional motion to multiaxial and multidirectional motion, and the responsible vertebral body for the maximum amplitude moved down gradually. Conclusions Modal analysis can better analyze dynamic characteristics of the thoracolumbar osteoporotic vertebral body. Patients with osteoporosis should try to avoid the specific vibration environment, so as to decrease the risk of intervertebral disc tissue degeneration, strain of thoracolumbar soft tissues and lesion in posterior structures of the vertebral body.
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Objective To investigate whether a 3D printed model of the contrlateral healthy distal radius, especially its articular accuracy, helps anatomical reduction and precise reconstruction of the fractured distal radius. Methods The CT data of bilateral radii were collected from 15 normal volunteers ( 11 males and 4 females with an average age of 22. 8 years ) between November and December 2016. After 3D reconstruction of the bilateral distal 1/3 radii, solid 3D models of left radius were mirrored and generated by 3D printing. The data of right radii ( reference group ) were compared with the data of the solid 3D models of left radius acquired through a 3D scanner ( test group ) using deviation analysis. Results The maximum volume difference between the 3D printed model and the contralateral radius was 6. 86％. The average volume of the reference group was 19, 165. 82 ± 3, 250. 50 mm3 and that of the test group 19, 310. 65 ± 3, 305. 15 mm3, showing no statistically significant difference between the 2 groups ( t= -0. 941, P=0. 363 ) . The maximum surface area difference was 3. 84％ between the 2 groups. The average surface area of the reference group was 5, 075. 80 ± 549. 34 mm2 and that of the test group 5, 139. 43 ± 572. 48 mm2, showing a signifi-cant difference ( t= -2. 451, P=0. 028 ) . The 3D deviation analysis showed a mean positive deviation of 0. 37 ± 0. 10 mm and a mean negative deviation of 0. 30 ± 0. 07 mm. The maximum mean square root was 0. 65. The 3D deviation was distributed mainly within 1 mm interval, with a distribution frequency of 96. 27％. Conclusions A 3D printed model prepared by high precision equipment is accurate enough to guide reconstruction of distal radius fractures in adults. In the treatment of complex fractures of the distal radius, a 3D printed model of the contralateral healthy distal radius can be used as a reference to achieve anatomical reduction and precise reconstruction of the fractured distal radius.
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<p><b>OBJECTIVE</b>To investigate the application of 3D printing and digital technology in preoperative assessment and planning of internal fixation surgery for complex tibial plateau fracture.</p><p><b>METHODS</b>Complex tibial plateau fractures and commonly used plates for tibial plateau were imaged using computed tomography (CT) to reconstruct the 3D fracture and plate models. The 3D models were used to perform virtual reduction and preoperative planning of internal fixation surgery with the most appropriate plates assisted by the 3D library of plates. According to the optimal plan, the 3D physical models of tibial plateau fractures and plates were 3D printed to simulate internal fixation operation. The effects of internal fixation were compared between the virtual surgery and the simulated surgery based on the 3D models.</p><p><b>RESULTS</b>The effects of internal fixation in the simulated surgery based on the 3D models were consistent with those of the virtual surgery. No significant difference was found in the screw length between the two surgeries.</p><p><b>CONCLUSION</b>The combination of 3D printing and digital design can improve the effects of internal fixation for complex tibial plateau fractures.</p>
Subject(s)
Humans , Bone Plates , Bone Screws , Fracture Fixation, Internal , Fractures, Bone , Printing, Three-Dimensional , Tibial Fractures , General Surgery , Tomography, X-Ray ComputedABSTRACT
<p><b>OBJECTIVE</b>To assess the optimal configuration of double-screw fixation for subtalar arthrodesis using finite element analysis.</p><p><b>METHODS</b>Three-dimensional finite element double-screw models of subtalar arthrodesis were reconstructed using Mimics 13.0, Geomagic 10.0 and solid works software based on the 3-D images of the volunteer's right foot. The external and internal rotation torques of 4 N·m were applied, and the micromotion at the bone-to-bone interface were measured to evaluate the initial stability of subtalar arthrodesis.</p><p><b>RESULTS</b>A neck screw plus an anterolateral dome screw was the most stable model. The peak micromotion at the fusion site of this fixation configuration were 41.67mnplus;0.49 and 42.64mnplus;0.75 µm in response to the respectively. A neck screw plus a posteromedial dome screw was the least stable model, with peak micromotion at the bone-to-bone interface of 61.76mnplus;1.00 and 62.32mnplus;0.90 µm, respectively.</p><p><b>CONCLUSION</b>A neck screw plus an anterolateral dome screw is the best fixation configuration while a neck screw plus a posteromedial screw provides the least stability of subtalar arthrodesis. Three-dimensional finite element models allow effective preoperative planning of the screw number and placement.</p>
Subject(s)
Adult , Humans , Ankle , Diagnostic Imaging , Arthrodesis , Methods , Bone Screws , Finite Element Analysis , Imaging, Three-Dimensional , Internal Fixators , Models, Anatomic , Software , Subtalar Joint , General Surgery , Tomography, X-Ray ComputedABSTRACT
Objective To systematically review the existing evidence about the effect of medial and lateral (crossed) entry pins versus only lateral entry pin fixation on the supracondylar fractures of the humerus in children.Methods Eligible studies were identified in Cochrane library,the Cochrane Bone,Joint and Muscle Trauma Group (till March 2011 ),Medline (from 1966 to March 2011 ),EMbase (from 1966 to 2011 ),CBM (from January 1979 to March 2011 ),PubMed,Wanfang Data (from 2000 to March 2011 ) and CNKI and the references of the included studies and several Chinese orthopedic journals were manually searched.Then,the randomized controlled trials (RCTs) and quasi-randomized controlled trials (CCTs) about two entries (crossed and only lateral pinning) for supracondylar fractures of humerus in children were collected.After evaluation of methodology with the enrolled studies,available data was extracted and systematic review was conducted via the method recommended by the Cochrane Collaboration.Results In total,five RCTs involving 311 patients were involved.Compared with the preoperative data,the meta-analysis results showed no significant difference in reduction stability in terms of change in Baumann angle and Carrying angle between the two groups.For the postoperative function outcome including complete reduction,Flynn grade and full return to function,no significant difference was found between the two groups.For the postoperative complications,there was no difference in the infection of pin tract,though lateral entry resulted in a significant lower incidence of the iatrogenic nerve injury compared with the medial and lateral entry.Conclusions With the Kirschner wire fixation for supracondylar fractures of humerus in children,current existing evidences indicate that the lateral entry of pinning has similar results in reduction stability,function outcome and incidence of pin tract infection compared with medial and lateral entry.Nevertheless,lateral entry,as a safe pinning technique,may effectively decrease the risk of iatrogenic nerve injury