What are the requirements for the hardness of silicone used in prostheses?

What are the requirements for the hardness of silicone used in prostheses?
The hardness of silicone used in prostheses needs to be determined according to different parts, usage requirements and individual conditions. It usually fluctuates between Shore A 10 and 60. The following are specific requirements:
Socket pad: The socket is the part where the prosthesis and the residual limb are in direct contact. The hardness of the silicone used for its pad is generally low, between Shore A 10 and 30. This is because the skin in the residual limb area is more sensitive, and soft silicone is needed to provide a comfortable fit, reduce pressure and friction, and prevent skin damage. For example, the pad of the lower leg prosthesis socket usually uses silicone with a Shore A hardness of about 20 to better adapt to the shape of the residual limb and disperse pressure.
Decorative prostheses: For some decorative prostheses that focus on appearance, the hardness of the silicone will be relatively moderate, between Shore A 30 and 50. This can not only ensure that the prosthesis has a certain degree of support and shape stability, but also simulate the softness and texture of human skin, making its appearance more realistic and natural. For example, the hardness of silicone for decorative hand prostheses is generally around 40 Shore A, which can better show the shape and details of the hand.
Functional prostheses: Functional prostheses need to have a certain degree of support and wear resistance, so the hardness of the silicone used is relatively high, between 40 and 60 Shore A. For example, when a thigh prosthesis bears the weight of the body and performs activities such as walking, the silicone needs to have a higher hardness to provide stable support and good durability, and silicone with a Shore hardness of 50 to 60 is usually selected.
Individual differences: Different amputees have different feelings and adaptability to the hardness of silicone. Some patients with sensitive residual limb skin or special needs may need softer silicone; while some patients with stronger muscle strength and greater activity may be more suitable for slightly harder silicone. Therefore, when choosing the hardness of prosthetic silicone, it is necessary to fully consider individual differences and make personalized customization and adjustments.