Below-Knee Prosthesis: How to Put On Your Prosthetic Leg

What Is a Below-Knee Prosthesis?

A below-knee prosthesis (also called transtibial prosthesis) is an artificial limb designed for people who have had an amputation below the knee joint. It consists of a custom-fitted socket that attaches to the residual limb, a pylon or shank that provides structure, and a prosthetic foot. Modern prostheses use suspension systems like pin locks or suction to keep the prosthesis securely attached during walking and other activities.

A below-knee prosthesis is designed to replace the function of the lower leg and foot after a transtibial amputation. This type of amputation preserves the knee joint, which is a significant advantage for mobility and rehabilitation. Because you retain your natural knee, you have better control over the prosthetic leg and typically achieve more natural walking patterns compared to above-knee amputees.

The prosthesis works as a complete system with several interconnected components. Understanding how each part functions helps you put on and use your prosthesis correctly. The socket is the most critical component because it forms the interface between your body and the artificial limb. A well-fitting socket distributes your body weight evenly, prevents painful pressure points, and allows comfortable walking for extended periods.

Modern below-knee prostheses have evolved significantly over the past decades. Today's components use advanced materials like carbon fiber, titanium, and specialized polymers that are both lightweight and durable. The prosthetic feet available range from basic solid ankle cushion heel (SACH) feet to sophisticated dynamic response feet that store and release energy during walking. Your prosthetist will recommend components based on your activity level, goals, and physical condition.

Main Components of a Below-Knee Prosthesis

Understanding your prosthesis components helps you maintain them properly and communicate effectively with your prosthetist about any issues you experience.

• Liner: A flexible sleeve, usually made of silicone or gel, worn directly against your skin. It cushions the residual limb, provides grip for suspension, and protects the skin from socket friction
• Socket: A custom-molded hard shell that holds your residual limb. The socket is shaped to match your limb's contours exactly and distributes pressure appropriately
• Suspension system: The mechanism that keeps the prosthesis attached. Common types include pin lock (a pin on the liner clicks into a lock in the socket), suction (airtight seal), or sleeve suspension
• Pylon: The vertical support structure connecting the socket to the foot, often made of aluminum, titanium, or carbon fiber
• Prosthetic foot: Replaces the missing foot and provides stability, shock absorption, and energy return during walking

How Do You Prepare Your Residual Limb?

Before putting on your prosthesis, you must prepare your residual limb by washing it with mild soap and warm water, drying it thoroughly, and inspecting the skin carefully for any redness, blisters, cuts, or areas of irritation. Apply any prescribed skin care products if recommended by your prosthetist, but avoid lotions or oils that could affect liner grip. This daily preparation routine takes only a few minutes but is essential for preventing skin problems.

Proper preparation of your residual limb is the foundation for comfortable and safe prosthesis use. The skin of your residual limb faces unique challenges – it is enclosed in a liner and socket for many hours each day, experiences pressure and friction during walking, and is prone to moisture buildup from perspiration. Taking a few minutes each morning to prepare your limb correctly prevents many common problems and helps you get the most out of your prosthesis.

Start by washing your residual limb with mild, unscented soap and warm water. This removes oils, dead skin cells, and any bacteria that accumulated overnight. Pay particular attention to areas that experience the most pressure from your socket, as these are most vulnerable to breakdown. Avoid using hot water, which can dry out the skin and cause irritation. After washing, rinse thoroughly to remove all soap residue, as leftover soap can cause itching and skin reactions inside the liner.

Drying your limb completely is equally important. Moisture trapped between your skin and the liner creates an environment where bacteria and fungi thrive, potentially leading to infections or skin breakdown. Use a clean, soft towel and pat (don't rub) your skin dry. Allow your limb to air dry for a few additional minutes before applying the liner to ensure all moisture has evaporated.

Daily Skin Inspection

Every day before putting on your prosthesis, take time to inspect your residual limb carefully. Use a mirror if necessary to see all areas, including the back and bottom of your limb. This inspection only adds a minute or two to your routine but can catch problems early when they are easiest to address.

Look for any of the following warning signs that indicate a problem with prosthesis fit or technique:

• Redness that doesn't fade within 15-20 minutes: Brief redness after prosthesis removal is normal, but persistent redness indicates excessive pressure
• Blisters or areas of raw skin: Usually caused by friction from poor socket fit or wrinkled liner
• Open sores or cuts: Require immediate attention – do not use your prosthesis until healed and you've consulted your prosthetist
• Unusual swelling: May indicate infection or need for socket adjustment
• Ingrown hairs or folliculitis: Small infected bumps around hair follicles, common in areas where the liner grips the skin
• Discoloration or bruising: Suggests excessive pressure at that location

How Do You Apply the Prosthetic Liner Correctly?

To apply a prosthetic liner correctly, first turn the liner inside out halfway. Place the turned-out portion over the end of your residual limb, then gradually roll the liner up and onto your limb while pushing out any trapped air. The liner should cover the entire residual limb without wrinkles or air pockets. For pin lock systems, ensure the locking pin at the bottom of the liner is centered. A correctly applied liner feels snug but not painful and provides uniform compression.

The prosthetic liner is arguably the most important component for daily comfort. It serves multiple critical functions: protecting your skin from the rigid socket, providing cushioning during weight-bearing activities, creating grip for suspension systems, and helping to manage perspiration. Taking time to apply your liner correctly each day prevents skin problems and ensures your prosthesis stays securely attached during activities.

There are several types of liners available, with silicone and gel liners being most common for below-knee prostheses. Silicone liners are durable and provide excellent grip, while gel liners offer superior cushioning for sensitive residual limbs. Your prosthetist selected your liner based on your skin condition, activity level, and suspension system. Regardless of type, the application technique is similar and requires practice to master.

The rolling technique is essential for proper liner application. Unlike pulling on a sock, which can trap air and create wrinkles, rolling ensures the liner applies evenly without gaps or folds. Air trapped between your skin and the liner creates pockets that can cause blisters during walking, while wrinkles concentrate pressure and lead to painful spots. With practice, you'll develop a smooth rolling motion that eliminates these problems.

Step-by-Step Liner Application

How Many Prosthetic Socks Should You Wear?

The number of prosthetic socks you need varies based on your residual limb volume, which fluctuates throughout the day and changes over time. Start with the number recommended by your prosthetist, typically one to three socks. Add socks if the prosthesis feels loose or you sink too far into the socket. Remove socks if it feels too tight or uncomfortable. The goal is a secure fit where your knee is level with the top of the socket when standing.

Prosthetic socks serve as fine-tuning tools for socket fit. Even with a perfectly made custom socket, your residual limb volume changes constantly. It may be larger in the morning due to fluid accumulation during sleep, smaller after activity as fluid is pumped away, and gradually smaller over time as tissue shrinkage continues post-amputation. Socks allow you to accommodate these changes without needing a new socket for every fluctuation.

Prosthetic socks come in different thicknesses, measured in "ply." A 1-ply sock is thinnest, providing minimal volume adjustment, while a 3-ply or 5-ply sock adds more bulk. Most people use a combination of sock thicknesses to achieve the right fit. For example, you might use two 3-ply socks in the morning when your limb is larger, then switch to one 3-ply and one 5-ply in the afternoon as your limb volume decreases.

Learning to manage your sock layers is an essential skill that develops with experience. Over time, you'll recognize the subtle signs that indicate you need to adjust – the prosthesis feeling loose and pistoning (moving up and down) means add socks, while pressure or discomfort means remove socks. Some people check and adjust their socks several times throughout the day, while others find their limb volume is relatively stable and can go all day with the same sock configuration.

Signs Your Sock Fit Needs Adjustment

How Do You Insert Your Limb Into the Socket?

To insert your residual limb into the prosthetic socket, sit on a stable surface with the prosthesis positioned in front of you. Insert your limb straight down into the socket, pushing firmly until you feel the suspension system engage. For pin lock systems, continue pushing until you hear the clicking sound that indicates the pin is locked. For suction systems, ensure proper seal by expelling all air. Stand carefully and check that your prosthesis feels secure before walking.

Putting your residual limb into the socket is the moment when all your preparation comes together. A smooth, straight insertion ensures proper alignment and prevents problems during the day. Rushing this step or inserting at an angle can cause the socket to seat incorrectly, leading to discomfort, skin problems, or an unstable gait. Taking an extra few seconds to do this correctly saves considerable trouble later.

The technique for socket insertion varies slightly depending on your suspension system. Pin lock systems are most common for below-knee prostheses – these have a pin attached to the bottom of the liner that clicks into a locking mechanism in the socket. You'll hear and feel distinct clicks as the pin engages, and most systems have a release button or lever to unlock when you want to remove the prosthesis. Suction systems rely on creating an airtight seal between the liner and socket, either with a sealing membrane or through a one-way valve that expels air.

The environment where you put on your prosthesis matters too. Choose a stable, flat surface where you can sit comfortably with your prosthesis positioned in front of you. A firm chair without armrests works well for most people. Having your prosthesis resting against a wall or piece of furniture can help keep it stable while you insert your limb. As you gain experience, you'll be able to don your prosthesis in various situations, but initially, creating a consistent, safe environment helps you develop good technique.

Step-by-Step Socket Insertion

How Do You Check If Your Prosthesis Fits Correctly?

Check your prosthesis fit by standing carefully and noting how the prosthesis feels. Your knee should be level with the top of the socket rim. The prosthesis should feel secure without excessive tightness. Take a few steps and assess stability – there should be no pistoning (up-down movement), rotation, or painful pressure points. If something feels wrong, don't ignore it – adjust your sock layers or consult your prosthetist if problems persist.

Checking your prosthesis fit is a critical daily skill that protects your skin and ensures comfortable mobility. A prosthesis that fits correctly distributes your weight evenly, stays securely attached during activities, and allows you to walk with an efficient gait pattern. A poor fit, conversely, leads to skin breakdown, fatigue, compensatory movement patterns that strain other joints, and reduced confidence in your mobility.

The standing check is your first assessment. When you stand, your knee should be approximately level with the top of the socket. If your knee is significantly above the socket rim, you're not fully into the socket – you may need fewer socks or need to push the prosthesis on more firmly. If your knee is well below the socket rim, you may have too few socks and are sinking too far in, which can cause pressure on sensitive areas at the bottom of the socket.

Walking reveals information that standing cannot. Take several steps and pay attention to how the prosthesis moves with your body. Pistoning – the prosthesis sliding up and down relative to your limb during each step – indicates poor suspension or too few socks. Rotation – the prosthesis turning relative to your limb – suggests socket fit issues that may require professional adjustment. Pain during walking, especially sharp or localized pain, requires immediate investigation.

Daily Fit Checklist

• Knee alignment: Check that your knee is level with the socket rim when standing
• Security: The prosthesis should feel firmly attached with no sense of instability
• Comfort: Pressure should be evenly distributed with no painful spots
• No pistoning: The prosthesis shouldn't slide up and down during walking
• No rotation: The prosthesis should stay aligned and not twist during activities
• Suspension engaged: For pin locks, verify the pin is fully clicked in; for suction, confirm the seal is airtight

How Do You Care for Your Prosthesis and Residual Limb?

Daily prosthesis care involves cleaning your liner with mild soap, washing your residual limb thoroughly, and inspecting all components for wear. Clean your liner inside and out each day, rinse thoroughly, and allow to air dry completely before next use. Wipe down your socket with a damp cloth weekly. Inspect your residual limb twice daily – morning and evening – watching for any skin changes. Store your prosthesis in a clean, dry location away from extreme temperatures.

Consistent daily care extends the life of your prosthesis components, prevents skin problems, and ensures reliable performance. Like any precision medical device, your prosthesis performs best when properly maintained. The liner especially requires daily attention because it contacts your skin directly and can harbor bacteria if not cleaned regularly. Fortunately, effective prosthesis care doesn't require much time – most people integrate it into their existing hygiene routines within a few weeks.

Your liner bears the brunt of daily use, absorbing perspiration, skin oils, and environmental contaminants. Washing it daily prevents bacterial and fungal growth that can cause skin infections or unpleasant odors. Use a mild, unscented soap – harsh chemicals or perfumed products can degrade the liner material or irritate your skin. Turn the liner inside out periodically to ensure thorough cleaning of all surfaces. Always allow your liner to dry completely before putting it on, as trapped moisture promotes microbial growth.

Your residual limb care routine should include both morning preparation (washing and inspection before donning the prosthesis) and evening attention (washing away the day's perspiration and inspecting for any new skin changes). This twice-daily approach catches problems early. A small area of redness noticed in the evening that resolves overnight is likely normal pressure response, while redness that persists or worsens indicates a problem requiring intervention.

Liner Care Guide

When to Replace Components

Prosthesis components don't last forever, and using worn-out components compromises your safety and comfort. Your prosthetist will assess component condition during regular check-ups, but you should also watch for signs of wear between appointments.

• Liner: Replace every 6-12 months or sooner if you notice tears, worn areas, persistent odor despite cleaning, or loss of grip. Some liners have wear indicators that show when replacement is needed
• Prosthetic socks: Replace when they develop holes, thin spots, or lose their cushioning properties. Most socks last 2-6 months with daily use
• Socket: May need replacement every 3-5 years, or sooner if your residual limb volume changes significantly due to weight fluctuation, further maturation, or medical conditions
• Mechanical components: Pylons, adapters, and feet typically last 3-5 years but may fail sooner with high activity levels. Report any unusual sounds, looseness, or visible damage immediately

What Should You Do If You Experience Problems?

If you experience problems with your prosthesis such as skin irritation, pain, socket fit changes, or mechanical issues, first try simple adjustments like changing sock layers. If problems persist, stop using the prosthesis and contact your prosthetist. Never continue using a prosthesis that causes skin breakdown, as this can lead to serious infections and significantly delay your rehabilitation. Most problems have solutions, but they require professional assessment.

Even with careful technique and good hygiene, problems sometimes occur. The key is recognizing problems early and responding appropriately. Many issues have simple solutions – a sock adjustment, a minor socket modification, or a technique correction. Others require professional intervention. Knowing the difference and acting promptly protects your health and keeps your rehabilitation on track.

Skin problems are among the most common issues prosthesis users face. Your residual limb skin was never designed to bear weight or be enclosed in a socket for hours each day, and it takes time to adapt. Minor redness after prosthesis removal is normal and should resolve within 15-20 minutes. Redness that persists longer indicates excessive pressure. Blisters, abrasions, and sores develop when friction occurs – often from wrinkled liners, improper sock application, or socket fit changes. These require rest (no prosthesis use) until healed and investigation of the underlying cause.

Socket fit problems develop as your residual limb changes over time. In the first year after amputation, volume changes can be dramatic as swelling resolves and tissues mature. Even years later, weight changes, muscle development or atrophy, and fluid fluctuations affect fit. Signs of poor socket fit include needing significantly more or fewer socks than usual, new pressure areas, instability during walking, and pain that wasn't present before. These problems typically require prosthetist evaluation and possible socket modification or replacement.

What Is Daily Life Like With a Below-Knee Prosthesis?

Daily life with a below-knee prosthesis involves developing routines for morning donning, managing fit throughout the day, and caring for your prosthesis and residual limb in the evening. Most people with below-knee amputations return to work, driving, sports, and other activities they enjoyed before amputation. Success requires patience during the learning period, attention to fit and skin health, and ongoing partnership with your prosthetic care team.

Adjusting to life with a prosthesis is a journey that looks different for everyone. Some people adapt quickly and are walking confidently within weeks of receiving their prosthesis. Others take longer, which is equally normal. Your physical condition before amputation, the health of your residual limb, your overall fitness, and your psychological readiness all influence how quickly you progress. Comparing yourself to others isn't helpful – focus on your own progress and celebrate each milestone.

Morning routines typically include limb hygiene, liner application, and prosthesis donning. With practice, this entire process can be completed in 10-15 minutes. Throughout the day, you may need to check your fit and adjust socks, especially during the first year when your residual limb volume is still stabilizing. Planning for these adjustments – keeping spare socks with you and knowing where you can sit comfortably to make changes – reduces stress and keeps you mobile.

Evening routines involve removing the prosthesis, washing your residual limb and liner, and inspecting your skin for any signs of problems. This is also a good time to reflect on how the day went – did anything feel different or uncomfortable? – and note any concerns to discuss with your prosthetist at your next appointment. Keeping a brief log of fit changes, skin issues, or activities that caused problems can help your prosthetist identify patterns and make better adjustments.

Returning to Activities

Most people with below-knee amputations can return to the activities they love, though some may require adapted techniques or specialized equipment. Walking is typically the first milestone, progressing from indoor walking with support to outdoor walking on varied terrain. Many people also return to driving (with appropriate vehicle modifications if needed for left-leg amputation), cycling, swimming, running, and even high-impact sports.

Work return depends on your job requirements and your physical progress. Desk jobs may be possible within weeks of receiving your prosthesis. Jobs requiring standing, walking, or physical labor may need longer rehabilitation and potentially workplace accommodations. Your rehabilitation team, including physical therapists and occupational therapists, can help you prepare for work return and advocate for any necessary accommodations.