Above-Knee Prosthesis: Donning Techniques, Preparation, and Troubleshooting

How Do You Don an Above-Knee Prosthesis?

Donning an above-knee (transfemoral) prosthesis is a precise process requiring proper technique to ensure optimal fit, comfort, and function. It involves careful preparation of the residual limb and the prosthesis, followed by a systematic approach to secure the limb within the prosthetic socket.

Understanding the Above-Knee (Transfemoral) Prosthesis

An above-knee prosthesis replaces a limb amputated above the knee joint. Its effectiveness hinges on the intricate connection between the residual limb and the prosthetic socket. Key components include:

• Socket: The custom-made interface that encases the residual limb. Its precise fit is paramount for comfort, control, and efficient power transfer.
• Suspension System: The mechanism that holds the prosthesis onto the residual limb. Common types include suction, pin/lanyard locking, vacuum, or various strapping/sleeve systems.
• Knee Unit: Mimics the anatomical knee, allowing for flexion and extension during gait.
• Shank: Connects the knee unit to the prosthetic foot.
• Foot: Provides ground contact, shock absorption, and propulsion.

The process of donning focuses primarily on correctly seating the residual limb within the socket and engaging the suspension system.

Preparation is Key: Before You Don

Thorough preparation is critical for a comfortable and functional fit, minimizing skin irritation and ensuring prosthetic longevity.

• Residual Limb Hygiene:
  • Wash your residual limb daily with a mild, unscented soap and warm water.
  • Rinse thoroughly and dry completely, paying special attention to skin folds.
  • Moisturize your limb if needed, but allow it to fully absorb before donning. Avoid greasy lotions directly before donning, as they can interfere with suspension.
• Skin Inspection:
  • Daily, visually inspect your entire residual limb for any redness, blisters, open sores, rashes, or areas of excessive pressure. Use a mirror if necessary to view all angles.
  • Report any persistent issues to your prosthetist or healthcare provider immediately.
• Liner/Sock Management:
  • Ensure any prosthetic liners (gel, silicone, urethane) or socks are clean and dry.
  • Check socks for holes, thinning, or stretched areas that could create wrinkles.
  • Have an appropriate range of sock ply (thickness) available to adjust for daily limb volume fluctuations.
• Prosthesis Inspection:
  • Inspect the inside of the socket for any foreign objects, cracks, or rough edges.
  • Check all connections, especially at the knee and foot, to ensure they are secure.
  • If using a pin-locking system, ensure the pin is clean and functioning. If using a suction valve, ensure it's clean and operational.

Step-by-Step Guide to Donning an Above-Knee Prosthesis

The specific donning technique will depend on your prosthesis's suspension system. Below are common methods:

Donning with a Prosthetic Liner and Pin/Lanyard System

This method uses a liner with a distal pin that locks into a receiver in the socket, or a lanyard that pulls the limb into place.

1. Roll on the Liner: Carefully roll your clean prosthetic liner onto your residual limb. Ensure it is pulled up fully and smoothly, with no wrinkles or air pockets between the liner and your skin. The pin or lanyard should be correctly positioned at the distal end.
2. Position the Limb: Sit comfortably, allowing your residual limb to hang freely. Position the socket opening in front of your limb.
3. Guide and Insert: Carefully guide the distal end of your residual limb (with the liner and pin/lanyard) into the socket opening.
4. Engage the Pin/Lanyard:
   • For Pin System: Push your limb firmly into the socket until you hear or feel the pin click into the locking mechanism. You may need to bear some weight or push down with your hands on the socket brim.
   • For Lanyard System: Thread the lanyard through the bottom of the socket. While pulling the lanyard, simultaneously push your limb into the socket until it is fully seated. Secure the lanyard firmly.
5. Check for Seating: Once engaged, attempt to pull the prosthesis away from your limb to ensure the pin or lanyard is securely locked.

Donning with Suction (Direct Skin or Liner with One-Way Valve)

This method relies on creating a vacuum seal between the limb (or liner) and the socket.

1. Prepare Limb/Liner: Ensure your residual limb (or liner) is clean, dry, and free of wrinkles. Some users may apply a thin layer of prosthetic lotion or a special donning spray to help the limb slide in easily.
2. Open Valve (If Applicable): If your socket has a one-way expulsion valve, ensure it is open or unscrewed slightly to allow air to escape.
3. Insert Limb: Position the socket opening in front of your limb. Carefully guide your limb into the socket, pushing down firmly and steadily.
4. Expel Air & Create Suction:
   • Weight Bearing: Slowly stand up, allowing your body weight to push your limb fully into the socket. You may hear air escaping.
   • Pistoning Motion: Gently "pistoning" (lifting and lowering your limb slightly within the socket) can help expel air and create a secure suction seal.
   • Close Valve: Once fully seated and air is expelled, close or tighten the expulsion valve.
5. Test Suction: Attempt to pull the prosthesis away from your limb. There should be significant resistance, indicating a proper suction seal.

Donning with a Pull Sock/Donning Aid (Often for Soft Inserts or Liner-less Sockets)

This method uses a thin, slippery sock to help pull the limb into a tight-fitting socket.

1. Apply Prosthetic Socks/Liner: If using prosthetic socks, apply the correct ply (thickness) directly to your residual limb, ensuring they are smooth and wrinkle-free. If using a liner, apply it as described above.
2. Apply Pull Sock: Roll or slide the pull sock (a long, tube-like sock often made of nylon or similar slippery material) over your residual limb and through the bottom opening of the socket.
3. Insert Limb: Carefully guide your limb into the socket, holding the pull sock taut from the distal end.
4. Pull Through: While maintaining gentle downward pressure on the socket, steadily pull the pull sock through the distal opening of the socket. This action draws your limb deeply into the socket.
5. Remove Pull Sock: Once your limb is fully seated, carefully pull the entire pull sock out from the bottom of the socket.
6. Secure Suspension: If your prosthesis uses additional straps or a sleeve for suspension, apply them now.

General Considerations for All Methods:

• Full Seating is Crucial: Ensure your limb is completely seated at the bottom of the socket. Incomplete seating can lead to discomfort, pressure points, and an unstable gait.
• Check for Comfort: Once donned, stand and take a few steps. Pay attention to any areas of pinching, excessive pressure, or discomfort.
• Adjust Sock Ply: If the prosthesis feels too loose, add a thin prosthetic sock. If it feels too tight or creates excessive pressure, remove a sock (if applicable). Limb volume can fluctuate throughout the day due to activity, hydration, and temperature.

Troubleshooting Common Donning Issues

• Difficulty Achieving Full Seating: Re-check your limb and socket for any obstructions. Ensure your liner/socks are smooth. Try a different donning technique or consult your prosthetist about socket fit.
• Pain or Discomfort: Remove the prosthesis immediately. Inspect your limb and the socket for pressure points, redness, or skin breakdown. Do not force the fit.
• Air Pockets (especially with suction): Re-don the prosthesis, focusing on expelling all air. Ensure the expulsion valve (if present) is functioning correctly.
• Skin Irritation: Ensure proper hygiene. If irritation persists, it may indicate a poor socket fit or an allergic reaction to materials.
• Prosthesis Feeling Loose or Too Tight: Adjust your prosthetic sock ply. If significant changes occur, your limb volume may have changed, requiring a prosthetist's assessment.

The Importance of Professional Guidance

Proper donning technique is initially taught by your prosthetist and physical therapist.

• Prosthetist: Your prosthetist designs, fabricates, and fits your custom socket. They will instruct you on the specific donning method for your prosthesis and make adjustments to ensure optimal fit and comfort. Ongoing adjustments may be needed as your limb volume changes over time.
• Physical Therapist: Your physical therapist will work with you on gait training, balance, and strengthening exercises. They can also help refine your donning technique to make it more efficient and safe.

When to Seek Professional Help

Consult your prosthetist or healthcare provider if you experience any of the following:

• Persistent pain or discomfort after donning.
• New or worsening skin irritation, redness, or breakdown on your residual limb.
• Significant changes in how the prosthesis fits (e.g., constantly too loose or too tight, despite sock changes).
• Difficulty donning the prosthesis despite trying correct techniques.
• Any damage to the prosthesis that affects its function or fit.

Mastering the art of donning your above-knee prosthesis is fundamental to your mobility, comfort, and overall quality of life as an amputee. With consistent practice and professional guidance, you can achieve a secure and functional fit every time.