Reachout Orthopedics - Issue 1

estimate both the prognosis and the growth potential. SH reported that the separation of the physeal plate in type 1 and 2 injuries occurs between the provisional calcification region, which is the weakest region of the four regions it contains, and the calcification region. The good prognosis in these two types is usually thought to be associated with the case that this fracture zone does not include the proliferative region where the original growth cells are located, and therefore, the blood vessels feeding this layer are not injured. On the contrary, the bad prognosis was seen in type 3 and 4 fractures because they penetrate the proliferative layer. Moreover, the crushing of the growth cartilage in type 5 fracture has the worst prognosis because of death of the growth cells and termination of growth [1, 2]. Distal femoral physeal fractures occur for just over 5% of all physeal injuries [4] with complications that require a secondary surgery 40–60% of the time [5]. In SH type 4 fracture, the fracture line goes through the epiphysis and the physis with a section of metaphysis (Fig. 1). In the treatment of intra-articular SH fractures, the aim is to minimize the level of injury in the physeal plate and complete the fracture recovery in a usual way close to perfection. A need always exists for an anatomical reduction with surgical treatment to reduce the poor prognosis of these fractures and prevent possible deformities [6–8]. Even if an open reduction for SH type 4 fracture is performed almost immediately, no biomechanical evidence is available other than a few studies on how fracture fixation is affected and how it affects the growth of cartilage under load [9]. The fixation generally can be achieved with screws or smooth Kirschner wires which passes through the metaphysis and rarely with plates such as pediatric physeal slide-traction plate (PPSP) when fracture is comminuted [10, 11]. It has been generally mentioned that the physis line should not be passed during implantation and partial fluted screws and optional ferrules should be used for the compression of the fracture [1, 7, 12, 13]. Damage to the physeal plate must be avoided during implantation. Otherwise, asymmetric growth can occur. The literature shows that the compression between fractures increases stability and consequently positively affects the rate of blood buildup and increases the rate of bone union. On the contrary, it has been noted that too much compression may lead to loosening of the screw and, thus, different complications may occur [14]. The present study searched for an answer to the question of how the compression impacted the physis line in a fracture site during the fixation made for an SH type 4 fracture. The results showed that the screw head began to compress the fracture line as soon as it rested on the bone cortex, and the rotation and impulse momentum led to a contusion in the physeal plate. If the distal femur physeal plate was transversely shaped in a straight line, it could only be shear stress, but it was observed that the wavy structure of the physeal plate created a compression stress in the physis. Theoretically, when a fracture line is compressed with a screw, an SH type 4 fracture is converted into an SH type 5 fracture with a worse prognosis and SH type 1 fracture with shear effect. If it is thought that the worst prognosis of the epiphysis fracture is the pressure on the physeal plate, the excessive stress may support bone formation and deformity and lead to some irreversible negative consequences such as avascular necrosis after the deterioration of blood circulation [1]. Although this situation may depend on many factors, it is directly related to the fixation pattern and technique [5]. Although classical textbooks noted that the compression should be applied in such fractures, this study was performed using the finite element method. Other experimental studies considering minimal changes have shown that this intervention creates an additional iatrogenic injury in the physeal line [7]. Also union of fractures is related to many factors such as being open or closed, age or mechanism of injury, and the other main factor is the interfragmentary compression. A consensus exists in many studies, which indicates the positive effect of compression between the fracture components. Besides the treatment of adults, interfragmentary compression is also recommended in pediatric fractures, especially physeal fractures. Epiphyseal fracture of the distal femur has a high risk, especially in terms of growth interruption and other complications [15–18]. The factors leading to this condition include type of the fracture, degree of dislocation, undulating structure of the physis and quality of fracture reduction with the fixation shape [19–21]. When the histology was viewed, physeal bar formation (bone bridge in physis) was found to be mainly responsible for angulation at the fracture line and growth complications [6, 19–21]. Generally, screws are used for treating SH type 4 distal femoral epiphyseal fractures. Also, the compression of the fracture line with partially threaded screws is recommended during fixation [7]. The compression of fracture line may reflect additional injury to the physis because of the undulating structure of the physis in distal femur. The treatment objectives were specified even for this type of fracture to achieve anatomical reduction and avoid additional injury to the physis; which is the safe technique and is not yet Theoretically, when a fracture line is compressed with a screw, a Salter-Harris type 4 fracture is converted into a Salter-Harris type 5 fracture with a worse prognosis and Salter-Harris type 1 fracture with shear effect. Fig. 1: Parallel screws configuration for SH type 4 fracture. Table 1: The bone screwing process parameters. Screw dia Ø (mm) Pitch (mm) RPM (rev/min) Feed rate (mm/min) M4 1.75 100–200 125 3 reachOut Orthopedics