During a fitting, patients may be asked to put on and take off the prosthesis, as well as to walk with it. Patients may also require training and practice in how to transfer their weight onto the prosthetic device (e.g., from sitting to standing to walking).

The prosthetist is likely to first build a prototype (temporary) prosthetic for the patient to test. This prototype is the basis for designing and building the final prosthetic. Because the final (definitive) prosthetic may be used for two or more years, it is recommended that patients report any issues with comfort and functionality of the device, especially if it causes pain. The final device is designed and built using the patient’s input from this testing period.

Problems with fit may occur for a variety of reasons. Prolonged sitting or improper body position during sleep can lead to contracture (shortening of muscle tissue, which inhibits movement) in the residual limb. Contracture can cause a poor fit of a prosthesis or can lead to the inability to use a prosthesis.

In addition, the socket must be designed to disburse weight load as much as possible. After an amputation, the residual limb ends up bearing a patient’s weight, when it was never intended to perform that function. Improperly designed sockets can cause continuing pain. If this is the reason for the pain, the prosthesis may need to be modified. A socket that is too tight can cause swelling and red, irritated skin in the residual limb.

The last step in fitting the prosthetic is choosing its cosmetic appearance. There are many possibilities. Patients may opt for a natural look that matches their skin tone, including realistic veins, freckles and hair. Others may choose a decorated leg that pleases their personality and individual tastes. Whatever the appearance, it is primarily aesthetic and has little to no effect on the prosthetic’s function.