The process of putting on an above-knee, or transfemoral, prosthetic leg requires specific steps to ensure a secure and functional fit. Proper donning technique is fundamental for comfort, stability, and preventing skin issues that can arise from friction or improper seating. A well-donned prosthesis allows the user to experience the full benefit of their custom-designed device, promoting confidence and mobility throughout the day. This guide provides a detailed, step-by-step approach to safely and effectively prepare your residual limb and secure your prosthetic socket.
Preparing the Residual Limb and Liner
The initial preparation of the residual limb and prosthetic liner is essential for a successful fit. Before donning, the skin must be clean, dry, and free of any lotions or creams, as moisture can lead to friction and skin breakdown inside the liner. Daily cleaning with a mild, antibacterial soap helps maintain hygiene.
The prosthetic liner acts as the interface between the skin and the hard socket and should be inspected for damage. To apply the liner, turn it completely inside out, exposing the gel interior, and place the end flat against the distal end of the residual limb. Gently roll the liner up the limb, ensuring it unrolls smoothly without pulling on the skin, which can cause tension and irritation. Ensure no air is trapped between the skin and the liner to achieve total contact.
Step-by-Step Donning Techniques
The method for inserting the limb into the socket depends on the suspension system, typically pin-locking or suction/vacuum. For a pin-locking system, the liner has a pin attachment that must be carefully aligned with the shuttle-lock mechanism inside the socket. The user generally stands and guides the limb into the socket, visually ensuring the pin is centered before applying full weight.
As the user applies weight, the pin is pushed into the lock, securing the prosthesis with a series of audible clicks. The user should ensure the pin is fully engaged for a secure hold. This system is often favored for its ease and speed of use, though it can sometimes lead to pistoning, or vertical movement, of the limb inside the socket.
Suction or vacuum suspension systems rely on creating an airtight seal to hold the prosthesis in place. One common method, especially with traditional suction sockets, involves using a donning sock or sheath over the liner to reduce friction during insertion. The donning sock is pulled through a valve hole at the bottom of the socket, which draws the limb fully into the socket as the sock is removed.
For active vacuum systems, the user may simply push the limb directly into the socket, sometimes using lubricant on the outside of the liner to aid seating. The goal is to achieve full seating, where the residual limb is settled into the deepest part of the socket. This ensures even pressure distribution. If the limb is not fully seated, the pressure distribution will be incorrect, potentially leading to discomfort or skin damage.
Securing the Socket and Suspension
After the residual limb is inserted into the socket, the final step is engaging and confirming the suspension mechanism. For a pin-locking system, this involves listening for the distinct, final click that signals the pin is fully locked. The user should gently attempt to pull the prosthesis off to confirm the lock is secure before putting full weight on the limb.
With a suction or vacuum suspension system, securing the socket means establishing the airtight seal. For a traditional suction socket, the one-way expulsion valve must be closed or capped to prevent air from re-entering the socket. In active vacuum systems, the external pump is typically activated to draw out air and maintain a consistent negative pressure, actively holding the socket to the limb.
Some users may also have auxiliary suspension components, such as a waist belt or straps. These straps should be fastened and adjusted to a comfortable tension that supports the prosthesis without restricting movement or compromising the primary suspension seal. Over-tightening auxiliary straps can unintentionally pull the limb out of the fully seated position.
Troubleshooting Fit and Comfort Issues
Even with perfect donning technique, changes in the residual limb’s volume can lead to fit and comfort issues. One common problem is pistoning, where the limb lifts slightly inside the socket during walking. This movement indicates a loss of intimate contact and is often addressed by adding prosthetic socks, measured in ply, over the liner to increase the limb’s overall volume.
Prosthetic socks manage the natural volume fluctuations of the residual limb, which can shrink due to fluid loss or activity. A general rule is to add a sock layer if the fit feels loose, or remove one if it feels too tight, to restore proper snugness. If a user needs to add more than 8 to 10 ply, it usually signals a major volume change that requires a professional socket adjustment from a prosthetist.
Pressure points or localized pain must be addressed promptly, as they can lead to skin breakdown. If a red mark on the skin does not disappear within 15 to 20 minutes of removing the prosthesis, it indicates excessive pressure in that area. Users should contact their prosthetist if pain or discomfort persists after adjusting sock ply, or if blisters and open sores begin to form.