Reachout Orthopedics - Issue 1

is very difficult in FEA technically. In this region because of its growth, the amount of cortical and cancellous bones always changes. Although this region is a mixture of cortical, cancellous bone and physis, we researched the indirect effect on the wavy structure of physis by compressing the screw. We think that the compression in fracture line can be measured by overlooking the anisotropic structure. For this reason, we accept it as homogeneous except the physis. The growth plate is not a trabecular or cortical bone. It is an area of cells where mainly soft tissue (collagen, etc.) processes to the bone just near the physis. The other limitation of our study we believe is that how much force kills the cells in proliferative layer. We do not have knowledge about this issue. We mentioned that cells die when compression occurs axially in SH type 5 fracture. What the amount of force is? Or anything, unknown, we did not find any explanation on this aspect. But in our study we believe that can say “do not compress the fracture line” because this force changes to axial load on physis may be causing cell die like SH type 5 injury, “only place the screws to protect the reduction position of fracture.” There are two ways of fixation methods on fracture line without compressing it. The first one is described here by using partially thread screw without rotating its head when it touches the bone, and the other one is using full threaded screws. After reduction of the fracture line, screws can be used in one of these ways. Although compression in the fracture line is a desirable condition in classical fractures that do not affect the growth cartilage, here it is not recommended in the surgical treatment of fractures involving growth cartilage of the distal femur. It is believed that only position protection with a screw after an anatomic re- duction works. Moreover, the prediction of how the prognosis of growth cartilage frac- tures occurs should be done by considering the implant and compression. In addition, al- though this is an ex vivo simulation study, it must be assumed that comparison of in vivo studies must be made to ratify such beliefs. Conclusions We know that FEA is a powerful simulation tool and results must be validated by in vivo studies. Since there is no study regarding the real physeal effect about the application of screw by compressing it in vivo, we believe that results from this simulation model indicate that additional iatrogenic physeal injury occurs. Here, we took attention on wavy structure of distal femoral physis and fixation of fracture; especially, compression by screws can affect the physis. The physeal plate is affected from von Mises, Tresca or principal stresses under the any force or moment. In biomechanical stresses, a great majority of the stresses on the physeal plate are absorbed by screws. Even if these stress values in epiphyseal plate are very small, the epiphyseal plate is likely to be damaged. Therefore, types and strength of materials such as screw used in this type of application are very important with regard to damage of bone or soft tissues. Also, you can see effects using different damage criteria. Especially, the minimum principal stresses show compressive stress better. The compressive stresses occur on the wavy surface of the epiphyseal plate. This confirms our analysis and indicates that minimum principal stresses show the compression stresses better than von Mises. The present study found that compression in SH type 4 fractures of the distal femur created an additional stress load on the physeal plate. It is believed that screws need to be fixed without compression to avoid an additional iatrogenic physeal injury. We also believe that to find the in vivo real effect on physeal plate during compression is very difficult without applying any simulation model. Because when we think that physeal plate is very thin, the application of strain or stress gauges to this area is very difficult. Since it is premature to state that compression created an additional stress load on the physeal plate in vivo, according to our results, it has been found that lateromedial compression in SH type 4 fracture of the distal femur caused an additional stress load on the physeal plate ex vivo. Compliance with ethical standards Conflict of interest: There is no conflict of interest any financial funding or materials in the manuscript. Ethical approval: Not required for used sawbones samples in this study. References available on request Healthcare.India@springer.com Source: Sermet Inal, Kadir Gok, Arif Gok, Alaaddin Oktar Uzumcugil, Sabit Numan Kuyubasi. Should we really compress the fracture line in the treatment of Salter–Harris type 4 distal femoral fractures? A biomechanical study. J Braz. Soc. Mech. Sci. Eng. 2018; 40: 528. DOI 10.1007/ s40430-018-1448-2. © The Brazilian Society of Mechanical Sciences and Engineering 2018. Although compression in the fracture line is a desirable condition in classical fractures that do not affect the growth cartilage, here it is not recommended in the surgical treatment of fractures involving growth cartilage of the distal femur. 7 reachOut Orthopedics