Regaining mobility after an amputation is an important rehabilitation step that follows the acute phase of recovery. This process covers fitting the person with a prosthesis and the person learning to walk with it. The information below is general in nature; all fittings are planned individually by the prosthetic and orthotic team in line with a specialist physician's assessment and prescription.
From initial prosthesis to definitive prosthesis
The process usually begins with an initial prosthesis made after the surgical wounds have healed. Most people use the initial prosthesis until the volume and muscles of the residual limb (the remaining limb) have stabilized. This period offers a valuable opportunity to assess a socket fit suited to the person's requirements and to determine the right components for the definitive prosthesis.
Components of a prosthesis
Component selection in a lower limb prosthesis varies according to the type of amputation, the condition of the residual limb and the person's physical capacity. For the two most common lower limb amputations, transtibial (below-knee) and transfemoral (above-knee), the following components are usually used together:
- A prosthetic socket that creates a secure and comfortable connection between the residual limb and the prosthesis.
- A socket liner and suspension system that keeps the prosthesis in place while walking.
- A prosthetic knee joint that helps control gait and the stance phase (above-knee only).
- A prosthetic foot that provides safety and stability while standing and walking.
- Adapters that help keep the prosthesis in the correct position.
- Cosmetic covers that personalize or protect the appearance.
Prosthetic socket
The socket is a critical component that forms the connection between the residual limb and the rest of the prosthesis. It is usually custom-made from light, durable materials such as carbon, silicone or lamination resin. The socket has three main functions: distributing axial forces evenly by supporting load transfer, stabilizing the user by absorbing horizontal forces, and providing a continuous connection between the limb and the socket during the swing phase.
Liner and suspension system
As explained in the article describing the function of the silicone liner, the liner and suspension system together keep the socket from slipping off the residual limb while walking. Suspension systems are typically designed to work in one of two ways: by negative pressure (a vacuum seal) or by a mechanical setup. The system suitable for the person usually depends on the shape and length of the residual limb.
Prosthetic knee joint
For people with an above-knee amputation, the knee joint is an important component. Prosthetic knees are generally divided into three groups according to how they function under load:
- Knees with no flexion under load (e.g., locking/brake knees, multi-axis polycentric knees).
- Knees that allow limited flexion under load.
- Knees that allow unrestricted flexion under load (e.g., those with hydraulic stance-phase safety and microprocessor-controlled knees).
While mechanical monocentric knees work simply and directly, polycentric knees may provide safety with correct alignment and additional toe clearance during the swing phase. Microprocessor-controlled knees may offer dynamic stabilization in the stance phase, additional control during swing, and support on stairs and ramps. The choice of knee is always based on the person's mobility level, lifestyle and activities.
Prosthetic foot
The prosthetic foot contributes to stabilization while standing and walking. Some factors that affect its performance are:
- Ankle functionality: The foot works differently depending on whether the ankle is mobile or fixed; fixed-ankle feet can be made from materials such as carbon or glass fiber with different flexion characteristics.
- Stiffness: Heel and forefoot stiffness affect the dynamic response during the gait cycle and safe initial contact.
- Shoe compatibility: For safety, it is recommended to avoid shoes with slippery soles and irregular heel heights.
In addition, adapters help the prosthesis stay in the correct position throughout the day, while some specialized adapters may provide more control in daily activities. Cosmetic covers can be chosen according to appearance preference.
This content is for informational purposes only; you should consult your physician for diagnosis and treatment.
