Design modifications and evaluation of the silicone artificial finger joints.

Background: There are many reasons that could lead to finger joint arthroplasty, and the most familiar reason is osteoarthritis. Silicone finger joint are the most commonly used implants. However, these implants might fracture with time and cause wear which will lead to chronic inflammation and synovitis for the patient and then implant failure.

Objective: The aim of this study is to improve the design of the silicone finger joint and simulate the different designs using finite element analysis (FEA) simulation.

Method: Three different designs were drawn and FEA has been used in this study using Solidworks software. The first design is the silicone finger joint design without any modification, the second one is modified design with added ribs to the junction of distal stem and hinge and the third design was added filler material inside the body of the artificial joint. An axial force with 625 N that was applied on the upper part of the distal stem which is nearly represents the maximum value of the grip strength for normal males.

Results: The results showed improvement on the design in which the concentrated stress at the junction of the distal stem and hinge of the design was distributed. In addition, the Von Mises stress was stable for the modified design with added ribs and the added filler material designs after 15°.

Conclusion: The design modification could improve the stress distribution and stability of the artificial finger joint and increase the lifetime expectancy of these implants.