For a transtibial (below-knee) amputee achieving a comfortable and secure fit inside a prosthetic socket is essential for mobility, safety, and long term skin health. One of the most common challenges prosthetic users faces is residual limb (stump) volume fluctuation.

Limb volume can change throughout the day due to activity levels, temperature, fluid retention and circulation. These changes may seem minor but even small volume differences can significantly affect how the prosthetic socket fits. 

Millimeters matter in prosthetics.

When the residual limb becomes smaller excessive movement will occur inside the socket. This movement increases friction and shear forces on the skin which can lead to redness, blistering, pressure sores and ultimately skin breakdown. If left unmanaged this may result in pain, reduced prosthetic use or the need for socket adjustments or replacement.

To manage these daily volume changes prosthetic users often rely on stump socks or volume socks. These socks are worn over the residual limb or liner and come in various thicknesses (commonly measured in “ply”). By adding or removing socks during the day the user can finetune the fit of the socket maintaining proper contact and stability.

Effective volume management helps ensure even pressure distribution inside the socket and reduced risk of skin injury. Patients are encouraged to monitor their limb regularly and adjust sock ply as needed and report ongoing fit issues to their prosthetist.

Proper education and proactive volume control play a critical role in long term prosthetic comfort and skin integrity.