Mechanical analysis of four different stainless-steel alloys used for knee replacement surgical tool

Surgical stainless steel is a grade of stainless steel used in biomedical applications. It has been widely used for orthopedic implants and surgical tools. Surgical steels are those with the best amount of corrosion and rust resistance. In addition to the stainless-steel corrosion resistance, some of it's alloys (316, 316L, 304 and 17-4 PH stainless steels) have additional properties that encouraged using them in surgical applications such as good biocompatibility, low risk for allergic reaction, ability to withstand intense sterilization processes used in the medical industry, oxidation resistant as well excellent tensile strength and fracture toughness. In this comparative study, these four stainless steel alloys have been mechanically tested to prove their effectiveness in a surgical tool used in aligning tibial component in knee replacement surgery. A load of 100N has been applied to the tool in maximum mechanical condition. The mechanical testing performed using ANSYS 19.0 as static structural system. Total deformation resulted was in the range (0.062-0.065 mm). Strain was in the range (0.79×10-3 to 0.82×10-3). Equivalent stresses were between 143.87 MPa to maximally 144 MPa for 304 alloy. Safety factor of 17-4PH stainless steel produced after analyzing it was 5.3169 while the other three alloys had a minimum safety factor of approximately 1.4. Yield strength and resulted safety factor proved that 17-4 PH stainless steel was the superior among the tested alloys. High safety factor means high durability of the metallic tool. Yet all alloys produced convergent deformation, strain and stress results. The differences between the four tested alloys were moderate and the numerical values were acceptable compared to the mechanical properties of the alloys. It can be concluded that these four alloys can be used safely to manufacture such surgical tools.