| Objective:To analyze the clinical data of adult normal calcaneus and the imaging data of calcaneu fractures,to design a miniature and adjustable external fixator for calcaneus,and to verify its feasibility by finite element analysis.Method:1.Collect the imaging results of calcaneal fractures,analyze and summarize the types of calcaneal fractures,and provide reference for the treatment of calcaneal fractures.Continuous into the hospital from October 2012 to December 2016 in our hospital patients with calcaneal fractures in a total of 347 cases(382 feet),patients were diagnosed by X-ray and CT.The imaging data of patients were evaluated the type and chosen the treatment by three senior orthopaedic surgeons.2.To obtain the normal X-ray and CT scan images of adults,and to use Mimics software to measure the anatomical parameters of adult normal calcaneus.40 cases were collected(20 males,20 females)adult normal calcaneus CT scan images,the image data into Mimics software,bone length,width and height parameters measurement of 3D reconstruction,calculated by the formula of calcaneal BMD values delineated higher bone density region for reliable needle points,based on the anatomical parameters above,design a new type of adjustable external fixation of calcaneus.3.Finite element analysis method was used to establish the finite element model of calcaneus Sanders II and III fracture,and the compressive stress was used to analyze the stability and stress distribution of the model.A collection of adult male volunteers,get the man ankle CT image,based on the model of external fixation design,using computer software to establish the Sanders II,III type calcaneal fractures after the finite element model,the loading stress,fracture displacement records,analysis of the stress distribution.Result:1.Finally included in the case of a total of 337 feet,according to the CT Sanders classification:type Ⅰ 78 feet(23.15%),type Ⅱ 167 feet(49.55%),type III 61 feet(18.10%),type IV 31 feet(9.20%).259 feet(76,85%)required surgical intervention.2.Males group total length,width and height of calcaneus were(74.52±5.01),(29.56±2.94),(44.21±4.26)mm;females group were(71.28±5.25),(26.85±3.21),(40.16±4.38)mm,all the projects between groups were different(P<0.05).It was found that the bone of the anterior part of the calcaneus,the tuberosity,the hill and the bone at the distance of the calcaneus were dense,which was a reliable insertion point.3.A new type of external fixator was used to treat Sanders II and Sanders type III fractures after loading,two models of overall peak displacement is divided into:0.2483mm,0.2747mm,stress peak value:110.3MPa,125.4MPa;steel nails were:0.1504mm,0.1736mm,the peak stress is:110.3MPa,125.4MPa;two models of calcaneal displacement peak were:0.2483mm,0.2747mm,the peak stress is:40.33MPa,38.13MPaConclusion:1.The establishment of the three-dimensional model of the calcaneus appearance,fracture morphology is clear,in line with the requirements of the experiment,the measured calcaneal anatomic parameters are accurate and reliable,provide an effective reference for the design of external fixator.2.The new adjustable external fixation of calcaneus can provide sufficient biomechanical stability for calcaneal Sanders Ⅱ,Sanders III,the ankle bone stress distribution is more reasonable,external fixation and kirschner needle exist stress concentration in the ideal range.When the external fixation was used to fix the fracture of Sanders type Ⅱ,the peak value and peak value of stress were smaller.The external fixator was more suitable for Sanders type Ⅱ fracture of calcaneus. |
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