Prosthetic Leg: What It Is, Who Needs It & How It’s Used

What is a prosthetic leg?

A prosthetic leg, or lower limb prosthesis, is an artificial replacement for part or all of your leg. If you can’t use your leg, either because of a birth defect or amputation, you might use a prosthetic leg to walk.

A leg prosthesis can replace as much of your leg as you need, from your foot, ankle and shin to your knee, thigh and hip. It can offer you greater mobility and the chance to live a more active lifestyle.

What is the purpose of a prosthetic leg?

Prosthetic limbs are assistive devices to enhance your mobility and independence. They mimic the functions of a human limb to help you do certain things better than you could without them.

Using a prosthetic limb can also help you maintain your overall musculoskeletal health. Making your different side more usable allows you to distribute your body’s workload more evenly across both sides.

What are prosthetic legs made of?

Modern prosthetic legs are made of strong but lightweight materials, like carbon fiber or fiberglass, titanium or aluminum. They also have some softer parts, like foam cushioning and silicone sleeves.

The moving parts at the joints might include mechanical springs and gears or computer microprocessors. Some prosthetic legs include hydraulic or pneumatic cylinders, which make movement smoother.

What do prosthetic legs look like?

Prosthetic legs can look different ways. Some are high-tech and look like robot limbs. Others are more low-tech and skeletal-looking. You can also get different types of “skins” to cover your prosthesis.

Some people customize their prosthetic legs with fun fabrics, logos or tattoos. Others prefer a low-profile look that’s custom-painted to look like their natural legs. Most cosmetic covers are removable.

What are the different types of prosthetic legs?

Different types of prosthetic legs replace different parts of your leg. You might need a prosthesis with an ankle joint, a knee joint and/or a hip joint. Different types also have different mechanisms at the joints.

Some prosthetics are purely mechanical, while others have computerized parts. Some move in limited ways, and others move in many ways. Some are designed for particular sports or other activities.

Amputation levels

Different types of prostheses are available for different types of lower limb amputations, including:

• Transtibial amputation: Amputation through your lower leg.
• Knee disarticulation: Amputation at your knee joint.
• Transfemoral amputation: Amputation above your knee and through your femur.
• Hip disarticulation: Amputation at your hip joint.
• Hindquarter amputation (external hemipelvectomy): Removal of your whole leg and part of your pelvis.

Above-the-knee and below-the-knee prosthetic legs

Your limb deficit or amputation level will determine the level of prosthesis you need. In general, an above-the-knee prosthetic leg is a more complex device than a below-the-knee prosthetic leg.

One difference is the knee joint. If your prosthesis is below the knee, it only needs a shin, ankle and foot, which may or may not be flexible. If it’s above the knee, it’ll need to include a functioning knee joint.

Your knee joint is central to the mechanics of walking. It bears much of your weight and affects your stability and balance on various terrains. It also determines whether your leg can run, bike or swim.

The attachment part of the prosthesis also needs to be more sophisticated, as the prosthesis must attach to a shorter lever arm. Generally, the higher the amputation level, the trickier it is to attach the prosthesis.

Mechanical and bionic legs

The joints in your prosthetic leg may be mechanical or bionic, which means they include computer microprocessors. These microprocessors enable the joints to automatically adjust to different terrain.

Both types have pros and cons. Mechanical legs tend to be more durable, lightweight and affordable than bionic legs. They aren’t “smart,” but you can use them for basic walking and sitting down.

Bionic legs use microprocessors to provide real-time feedback about how you’re using them. They adjust to different activities and environments more like a natural leg would. Some are also programmable.

Both mechanical and bionic legs may include pneumatic or hydraulic components (compressed air or water). These provide adjustable resistance while walking, which allows for a more natural gait pattern.

What are the components of a prosthetic leg?

Prosthetic legs have several components, which are sometimes interchangeable. When you and your prosthetist design your custom prosthesis, you’ll discuss each of these components.

• Socket. The socket is the part that connects your prosthesis to your existing limb. It’s custom-made to fit your existing limb, and you’ll have several fitting appointments to perfect the fit. You’ll usually wear a changeable liner or “sock” between your limb and the socket.
• Suspension. The prosthesis connects to the socket by some type of suspension system. There are many types of prosthesis suspension systems, including straps or belts, suction liners, pin-locking liners, electric vacuum pumps and neoprene sleeves that “grip” the prosthesis.
• Skeleton. This is the “bone” part of a prosthetic leg, which connects the socket with the joint components. It’s also called the connector, adapter or frame. It’s often a type of metal pipe, or pylon, with connecting parts. Sometimes, it’ll have a softer, limb-shaped material over it.
• Joints. An above-the-knee prosthesis will need a knee joint, and sometimes a hip joint. These might be mechanical, pneumatic or hydraulic, and/or powered (bionic). Different types may be better for different people. You’ll also need an ankle joint, but this is usually part of the foot.
• Foot. The prosthetic foot is the terminal device at the end of your prosthetic leg. It may or may not resemble a human foot. Prosthetic feet can be low- or high-tech, with ankles that move in a variety of ways. Special feet can accommodate swimming, running, skiing or other sports.

Who can benefit from a prosthetic leg?

You might benefit from a prosthetic leg if you’ve had a lower limb amputation or have a congenital limb difference that makes walking difficult. However, not everyone benefits equally from a prosthetic leg.

Many factors can influence how much you’re likely to benefit from a prosthetic leg, and what complications you may face along the way. Before recommending one, your provider will want to know:

• Is your existing limb in good condition to use with a prosthesis?
• Do you have much pain in your existing limb or phantom limb?
• How much range of motion does your existing limb have?
• What’s the condition of your other leg?
• What are your mobility goals?
• How much rehabilitation and training can you commit to?
• Do you have insurance coverage or other funding for the type of prosthesis you want?
• What kind of moral support system do you have?

What are the steps involved in getting a prosthetic leg?

Getting a new prosthetic limb and learning to use it is a huge undertaking. It will take time, patience and practice on your part. It may be frustrating at times, and you’ll need to manage your expectations.

Here’s a brief breakdown of the steps involved: