Prosthetic donning is the process of securely attaching an artificial limb to the residual limb, a foundational daily skill for anyone using a prosthesis. This procedure must be performed correctly every time, as the proper connection between the body and the device is directly related to comfort, mobility, and the long-term health of the residual limb. While it may seem complicated initially, consistent practice transforms the donning process into a routine part of daily life. The specific steps depend heavily on the type of suspension system used, but the overall goal is achieving an intimate and stable fit within the prosthetic socket.
Pre-Donning Preparation
Proper preparation of the residual limb is the first step toward a successful prosthetic fit. This begins with meticulous hygiene, requiring the limb to be washed daily with mild soap and water, paying attention to any skin folds or creases. Thorough drying is equally important, as residual moisture can contribute to skin breakdown, friction, and the growth of bacteria within the socket and liner.
After cleaning, a careful skin inspection is necessary to check for redness, irritation, blisters, or open wounds, especially since these problems can escalate rapidly with device use. Users should avoid applying lotions or moisturizers unless specifically directed by a clinician. If used, they must be fully absorbed before the liner is applied to prevent slippage and loss of socket control.
The final preparation step involves managing the residual limb’s volume, which naturally fluctuates throughout the day due to temperature, activity, or fluid retention. Volume changes are managed primarily through prosthetic socks, which come in different thicknesses, known as “ply” (typically one to five ply). Adding or removing socks helps maintain the necessary intimate fit, ensuring the limb is snug without excessive pressure or looseness. If the socket fit requires more than 10 to 15 ply of socks, the socket likely needs professional adjustment or replacement by a prosthetist.
Understanding Suspension Systems
The mechanism that keeps the prosthetic leg securely attached to the residual limb is called the suspension system, and the method of engagement varies significantly between the three primary types. The pin/lock system uses a gel liner with a rigid pin attached to its distal end. This pin is inserted into a shuttle-lock mechanism housed in the bottom of the prosthetic socket. This system provides an audible click when the pin is engaged, offering a simple and secure connection, though it requires the user to precisely align the pin with the socket’s hole.
The suction or seal-in system relies on creating a negative pressure seal between the socket wall and the residual limb. This is achieved either through a direct skin-to-socket fit or by using a liner that incorporates an airtight gasket or sealing ring. The goal of this system is to expel air as the limb is pushed fully into the socket, with a one-way valve often used to maintain the vacuum and prevent air from re-entering.
The vacuum-assisted suspension system is a more advanced version of the suction system. This technology utilizes an active pump, either mechanical or electronic, to continuously pull air out of the socket after donning. The constant negative pressure achieved by the pump creates a secure and comfortable fit by preventing pistoning, which is the vertical movement of the limb within the socket during gait.
Step-by-Step Donning Techniques
The initial step for nearly all systems is to apply the prosthetic liner smoothly and without wrinkles over the residual limb. The liner, which is typically a silicone or gel material, should be inverted and then rolled onto the limb from the bottom up, ensuring no air is trapped between the skin and the liner material. For pin/lock systems, it is crucial to ensure the pin at the end of the liner is centered and aligned with the limb’s long axis to facilitate proper engagement later.
After the liner is applied, any necessary prosthetic socks are pulled on over the liner, ensuring they lie flat without folds or wrinkles that could cause localized pressure points. The next action is to insert the prepared limb into the rigid socket, a process often done while seated to maintain balance and control. The user must apply steady, downward pressure, sometimes using a slight twisting motion, until the limb is fully “seated” or “bottomed out,” meaning the distal end of the limb is properly positioned in the socket.
The final step involves engaging the specific suspension mechanism to secure the leg. For a pin/lock system, the user listens for the distinct clicks as the pin slides into the shuttle lock, confirming the limb is held firmly in place. With a suction system, engagement is complete once the limb is fully seated and the one-way valve has expelled the air, creating the seal. For vacuum-assisted systems, the pump is either manually or automatically activated after seating to establish the active vacuum.
Addressing Common Fit Issues
Even with proper technique, common fit issues can arise immediately after donning, requiring prompt troubleshooting before walking. One of the most frequent problems is pistoning, where the residual limb moves up and down inside the socket during use, indicating a loose fit. This vertical movement is corrected by adding a prosthetic sock or increasing the ply of the current sock to fill the excess space and restore the intimate connection between the limb and the socket wall.
Another issue is localized discomfort or redness that persists for more than 15 to 20 minutes after the prosthesis is removed. This often signals an area of excessive pressure caused by an incorrect alignment or a wrinkle in the sock or liner. If the discomfort is caused by volume fluctuation, the solution is to adjust the sock ply. If it is due to mechanical pressure, the user should immediately take the prosthesis off and inspect the liner and skin before attempting to re-don.
A feeling of the limb not being fully seated, or “bottomed out,” can suggest a distal air pocket, which is a problem in suction systems. This is sometimes fixed by slightly pulling on the prosthetic foot or using a small amount of liquid, like rubbing alcohol, on the seal of the liner to help the limb slide down and push the remaining air out. Persistent issues with fit, pain, or skin compromise that cannot be resolved with sock management require immediate consultation with a prosthetist, as they may indicate a need for a professional socket adjustment or realignment.