Finite element analysis of three-dimensional frame screws and minimally invasive plate for fixation of Sanders III calcaneal fractures
Kong Dewei1, Song Chao2, Wu Liang2, Wu Ming2, Gong Lulu3, Wang Jiaqi1, Pan Hongyuan1, Fan Xinbin2, Zhang Yan2
1Postgraduate Training Base, Shanghai Pudong New Area Gongli Hospital, Ningxia Medical University, Shanghai 200135, China; 2Department of Orthopedics, Shanghai Pudong New Area Gongli Hospital, Shanghai 200135, China; 3College of Life Science and Technology, Tongji University, Shanghai 200092, China
Abstract: BACKGROUND: Satisfactory clinical results have been achieved in the treatment of Sanders III calcaneal fractures by percutaneous compression fixation with three-dimensional frame screws. However, whether the stability of minimally invasive plate internal fixation can be achieved in terms of biomechanics, and the advantages and disadvantages after comparison are still unknown.
OBJECTIVE: To investigate the fixation effect of different internal fixation devices on Sanders III calcaneal fractures by finite element analysis.
METHODS: A finite element model of Sanders III calcaneal fracture was made based on CT data of a 26-year-old healthy male volunteer. The calcaneal fracture models were fixed by minimally invasive three-dimensional frame screws and minimally invasive Y-plate. The longitudinal loads of 350 and 700 N were applied respectively. The displacement and stress distribution of the two models were analyzed, and the stability of each model was compared.
RESULTS AND CONCLUSION: (1) The peak stress of bone block and implant in the minimally invasive three-dimensional frame screw model was significantly lower than that in the minimally invasive minimally invasive plate model. The average stress of bone block and implant in the three-dimensional frame screw model was also significantly lower than that in the minimally invasive plate model. (2) The maximum displacement of the two models was located at the medial side of the articular surface of the posterior talus, and the maximum displacement of the three-dimensional frame screw model was smaller than that of the minimally invasive plate model. (3) The longitudinal displacement between the anterior fragment and the medial fragment of the minimally invasive plate model was smaller, and the transverse and vertical displacement between the medial fragment and the middle fragment of the three-dimensional group screw model was smaller. (4) It is concluded that both of the two internal fixation models can provide satisfactory fixation effect. The three-dimensional frame screw model can provide better transverse and vertical stability with more uniform stress distribution and smaller comprehensive displacement of bone fragments, while the minimally invasive plate has more advantages in maintaining longitudinal stability.
Key words: calcaneal fracture, biomechanics, Sanders III type, internal fixation, finite element analysis, screw, minimally invasive plate, minimally invasive