| Background: Adult-acquired flatfoot deformity(AAFD)is a common foot deformity that causes pain and other symptoms and seriously affects the quality of life of patients.Lateral Column Lengthening(LCL)is an important treatment for AAFD,which can be divided into Evans osteotomy and Hintermann osteotomy,among which Evans osteotomy is performed mainly by osteotomy between the anterior and middle surfaces of the talocrural joint.However,Evans osteotomy may damage the inferior talocrural joint,while Hintermann osteotomy is performed between the middle and posterior articular surfaces,which is relatively less likely to damage the inferior talocrural joint surface.In this study,we investigated the safety of Evans osteotomy in local cases by observing the morphology of the inferior talar joint and the biomechanical effects of Evans osteotomy on the surrounding joints and soft tissues.Objective: To investigate the safety of LCL surgery in local cases by observing the morphology of the inferior talar joint in the region,and to investigate the orthopedic ability of different sizes and shapes of implants and their stress effects on the surrounding joints and soft tissues by simulating LCL surgery with the AAFD model.Methods: Part I.Observation of the inferior talofibular joint morphology in cases from our region 1.Collecting CT data from normal patients with hindfoot who had CT scans of the foot and ankle performed at the Department of Radiology,Xiangya Hospital between January 2017 and March 2022 and storing them in Digital Imaging and Communications in Medicine(DICOM,hereinafter referred to as DICOM)format.2.Perform 3D reconstruction of the patient’s foot and ankle CT using Materialise Mimics 21.0,using intelligent segmentation to show the talus and heel bones separately and fully expose the subtalar articular surface.3.To observe and count the types of inferior talofibular joints in the data collection population.Part II.Simulating LCL surgery on the AAFD model to investigate the orthopedic ability of different shapes and sizes of implants and their stress effects on the surrounding joints and soft tissues.1.Develop the AAFD finite element model.2.Validation of the model to confirm its validity.3.Perform LCL surgery on the model using implants of different sizes and shapes,and observe the joint stress distribution and soft tissue stress changes during the procedure.Results.Part I.1.In the cases collected in this study,partial fusion of the anterior mid-articular surface(type B)was the most common form(44.18%)of the articular surface of the Achilles of the talocrural joint,followed by independent anterior mid-articular surface(type A)and complete fusion of the anterior mid-articular surface(type C),both of which were 23.26%,and the least common type was type D,which was only 9.3%.In addition,there are very few special types.2.Among the morphology of the articular surfaces of the talus,the most common type was partial fusion of the anterior mid-articular surface(type B,80.6%),followed by the independent type of the anterior midarticular surface(type A,12.68%),and the least number was complete fusion of the anterior mid-articular surface(type C,6.72%).3.In the ratio of paired heel and talar articular surfaces morphology,the most common heel-talar pairing was anterior mid-articular surface partially fused-anterior mid-articular surface partially fused(B-B,36.8%),followed by anterior mid-articular surface completely fused-anterior midarticular surface partially fused(C-B,21.6%).Part II.1.Through finite element analysis,we found that the degree of correction of both the triangular bone block and the rectangular bone block increased with the increase of the width of the bone block,and the rectangular bone block had a stronger orthopedic ability relative to the triangular bone block.2.The LCL resulted in an opposite trend of the lateral and medial plantar fascia tension.As the width of the bone block increases,the stress on the medial side of the bone block decreases,while the stress on the lateral side increases.3.The stress in the superior medial calcaneal ligament of the heel navicular(SMCN)decreased with increasing bone block width,with a more rapid decrease in the rectangular bone block group.In contrast,the stress in the inferior calcaneonavicular(ICN)ligament decreased with the lengthening of the triangular bone block and increased with the lengthening of the rectangular bone block.4.With the lengthening of the rectangular bone block,the center of pressure in the heel dice joint shifted to the medial side,resulting in a decrease in contact area but an increase in peak pressure,and the center of pressure in the talonavicular joint also shifted to the medial side,but both contact area and peak pressure decreased,and both joints had poor joint coverage.As the width of the triangular bone block increased,the center of pressure in the talonavicular joint also shifted to the medial side,but the contact area did not decrease significantly and the peak pressure decreased slightly.The contact area of the heel dice joint decreased,and the peak pressure increased significantly.The use of triangular bone block group had better coverage of both joints compared to the rectangular bone block group.Conclusion: In the cases collected in this study,the anterior mid-articular surface partially fused type was the most common type;therefore,osteotomy of the anterior part of the heel in Evans osteotomy may cause damage to the inferior talar articular surface,and careful preoperative evaluation of the patient and caution are required when using this procedure;rectangular implants have a greater orthopedic ability than triangular implants,and as the width of the implant increases,the orthopedic ability The rectangular implant has greater orthopedic capacity than the triangular implant,and as the width of the implant increases,the orthopedic capacity increases gradually,but the rectangular implant results in greater stress on the heel dice joint and is more likely to lead to joint degeneration.16 figures,8 tables,86 references... |
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