Comparative Effectiveness of Socket Casting Methods: Improving Form and Fit

One of the most important components of restoring function in persons with lower limb amputation is the precise fitting of the prosthetic socket to the residual limb. However, this is challenging because the residual limb is dynamic in shape and volume. Additionally, prosthetic socket fabrication processes influence socket fit. These processes typically consist of residual limb shape capture, positive mold rectification, initial diagnostic socket fitting, and definitive prosthesis delivery. The most prevalent residual limb shape capture method involves a negative wrap cast in a non-weight bearing position and manual manipulation of the cast to conform to the residual limb shape. With this technique it is challenging to accurately capture the bony contours and distribute pressure evenly around the residual limb. To improve shape capture, techniques that rely less on manual manipulation by the prosthetist, such as standing hydrostatic pressure casting with a water cylinder have been developed. Given the use of physics to shape the residual limb, it has been proposed that pressure casting results in better fitting and more comfortable sockets, however this has not yet been demonstrated. The overall objective is to compare hand casting to standing hydrostatic pressure casting using a water cylinder in persons with lower limb amputation. Our overall hypothesis is that standing hydrostatic pressure casting with a water cylinder will lead to more consistent and efficient residual limb shape capture and improved initial socket fit and comfort compared to hand casting.

Inclusion criteria

• unilateral lower limb amputation (transtibial and transfemoral)
• current prosthesis users

Exclusion criteria

• poor residual limb sensation
• a superficial neuroma that is painful to pressure
• an open sore on the residual limb
• a residual limb circumference or body weight that exceeds the size or weight limits of the Symphonie Aqua SystemTM (i.e., >58cm and 170kg for persons with transtibial amputation and >78cm and 170kg for persons with transfemoral amputation
• persons who are unable to stand for the 4-6 minutes required for casting (e.g. persons with bilateral amputations).
• persons with new amputations (i.e., have been an amputee for less than 1 year)
• persons with transfemoral amputation who have a known silicone allergy or a femur length less than 5 inches