Lower Limb Prosthetics: Built for Mobility & Independence
Our unique ability to build and adjust any kind of lower limb prosthetics right in-house allows us to get you your mobility and independence back faster. But it also gives us the creative control to design innovative devices that are perfectly tailored to your specific wants, needs, level of amputation, and goals. Our mission is to help you get back to living the way you want. And to us, that means doing more than just delivering you the right device – but connecting you to our amputee community and any resources you need to get back the life you want. We are here to help!
The Components of Lower Limb Prosthetics
I’ve had other prosthetics before, and this was really life-changing because the fit is so comfortable. The technology of the feet is accelerated to the point where, if I have pants on, you can’t tell I have a prosthetic leg.
Below-Knee Amputee 17 years, Allcare Patient since 2018 -
Lower limb prosthetics are typically made up of a socket, suspension, pylon, and foot. Depending on the level of amputation, however, additional components, such as a knee joint and hip joint, may be necessary.
A socket is the place where your residual limb will reside. Much of a prosthetist’s experience and skill go into creating a custom socket, as its fit is critical to the comfort of your prosthesis. Every socket must be custom-designed for each patient and then adjusted as necessary for maximum comfort and functionality.
The suspension is the component or method that is used to secure the prosthesis to the residual limb when you are walking or running. There are many different suspension methods, with the three most common being: vacuum, shuttle lock, and passive suction. Multiple suspension units can be used at the same time, depending on the level of amputation and needs of the patient. For more information, including the pros and cons of each, check out Ottobock’s overview of these suspension methods here.
The pylon is a structural piece of a prosthesis that acts much like the shin bone, connecting all of the different components of the prosthetic leg together. The pylon is responsible for transferring the load of body weight to the foot and the floor.
The foot you choose for your prosthetic will depend on your individual goals. There are many options available – and each style of foot performs different functions. Check out the following resource for more information on the types of feet available, including the advantages and disadvantages of each.
For more information on knee units and hip joints, see sections below covering above-knee prosthetics, including knee disarticulation, hip disarticulation, and hemipelvectomy amputation.
Alignment of Lower Limb Prosthetics
The alignment of a lower limb prosthesis refers to the position of the socket in relation to the foot and knee. Much like the design of the socket, proper alignment takes a lot of skill, expertise, and experience – and is absolutely critical to the fit, comfort, and functionality of your prosthetic leg. Alignment happens before you try your prosthetic on, then again during your first fitting, and often continues throughout the rehabilitation process to ensure a perfect fit.
Limb Loss Below the Knee – Transtibial Prostheses
A below-knee amputation involves the removal of the lower limb between the knee joint and the ankle. This is the most common type of amputation. At Allcare, we design our below-knee prosthetics using custom-built sockets and multiple suspension systems. Our custom-made sockets are designed to stabilize and control the tibia to ensure maximum comfort and range of motion at the knee. By using multiple suspension systems, we are able to provide an intimate connection of the prosthesis to the remaining anatomy.
Negative pressure systems (vacuum suspension): A negative pressure system uses a suspension that is created with direct contact between the liner and the socket wall. With this system, a pump evacuates the air out between the liner and socket, creating a negative pressure that is the same across the entire surface. To seal off the system, an external sleeve or seal is used at the top of the socket. The result is an unparalleled socket fit that helps to manage limb volume changes, comfort, and mobility.
Microprocessor Foot and Ankle Systems: The Empower Ottobock Ankle is the next generation design of the BiOM Ankle and is still the only prosthesis available on the market today with powered propulsion. It is characterized by the following features: power, control, and stability. The Ossur PROPRIO FOOT has computers and sensors embedded within its system to sense and adapt to varied terrain. This foot provides powered dorsiflexion – meaning the ability to raise the toes up – with passive plantarflexion, or movement of the toes down. This allows for improved foot clearance when walking on uneven terrain, steps, and ramps.
Limb Loss at the Ankle: Syme & Chopart Prostheses
Symes is an amputation through the ankle in which the heel pad is preserved. Chopart is an amputation through the Midtarsal joint. Both require a similar prosthetic to the below-knee amputation, except with Syme and Chopart, the socket also serves as the shank. Due to the short space between the end of the residual limb and the floor, a special type of foot – usually a modification to one of the popular designs – must be used. Also, because of the shape of the residual limb, no extra provision for suspension is necessary.
Limb Loss Above the Knee & Knee Disarticulation – Transfemoral Prostheses
An above-knee amputation involves the removal of the lower limb at or above the knee joint, while knee disarticulation leaves the femur and patella untouched. In either case, a prosthetic for this level of amputation will include a knee system and a carbon fiber socket with a flexible insert. The socket is fabricated using either a liner or skin fit system that uses a one-way valve to create an air-tight seal between the residual limb and the prosthetic socket. This allows for complete contact and eliminates any pistoning, or movement of your limb in your prosthesis as you walk, that can occur with other suspension systems.
Double Wall Socket
This prosthetic design incorporates an inner air-tight socket that gets locked into an outer containment frame. This system allows you to incorporate a vacuum system into your above the knee prosthesis.
Microprocessor Knee Systems
Rheo Knee®, C-Leg®, Genium™, Bionic Prosthetic System, X2 & X3 Prostheses: These devices are equipped with a sensor that can detect when the knee is in full extension and then adjusts the swing phase automatically. This allows for a more natural walking pattern of varying speeds. These microprocessor devices can also improve stance control, stability, function, and safety by providing a more controlled swing and stance phases of gait. For example, the sensors are designed to recognize a stumble which then stiffens the knee to help avoid a fall. Other potential benefits of microprocessor-controlled knee prostheses are improved ability to navigate stairs, slopes, and uneven terrain, and reduction in energy expenditure and concentration required for ambulation.
Next-generation devices such as the Genium Bionic Prosthetic System and X3 Prostheses use additional environmental input (e.g., gyroscope and accelerometer) and more sophisticated processing that is intended to create more natural movement. One improvement in function is step-over-step stair and ramp ascent. They also allow the user to walk and run forward and backward. The X3 is a rugged version of the Genium that can be used, for example, in water, sand, and mud.
Hip Disarticulation & Hemipelvectomy
A hip disarticulation is an amputation that removes the entire lower limb through the hip joint. A hemipelvectomy is an amputation that removes the entire lower limb at the hip level plus the pelvis. At Allcare, we use individually custom molded hip sockets, hydraulic hip joints, microprocessor knees, and carbon fiber feet to ensure maximum comfort and functionality for our patients in need of this level of prosthesis.
Hydraulic Hip Joints
At Allcare, we use the most innovative hydraulic hip joints available on the market today. By using a hip that is controlled by a hydraulic piston, stance extension can be regulated at the hip, allowing for a smoother and more energy-efficient gait. It also allows for better control of your step length and gait.
Click on the following link to learn more about one of the hydraulic hip joints we use: the Helix3D Hydraulic hip joint by Ottobock, which provides a natural, three-dimensional hip movement in swing and stance phase via hydraulic controls.
Lower Limb Prosthetics: Partial Feet
A partial foot prosthesis can help distribute the weight-bearing forces comfortably on the remaining foot, which enables you to walk for a longer period of time without pain or discomfort. Today’s technology, materials, and fabrication processes all contribute to how amazingly realistic modern partial foot prostheses can look.