Lower Limb Prosthetics

Lower Limb Prostheses

Lower limb amputations can occur for various reasons such as poor circulation, traumatic accident, infection, etc., and at different levels (see below), resulting in differing challenges. A common factor for all individuals is the more quickly you return to walking, the better your prosthetic rehabilitation outcome is.

The world of prosthetics is oftentimes overwhelming and seems to have its own vocabulary. To make the process less confusing, you can schedule an appointment to meet with a prosthetist as soon as you know you will be undergoing an amputation. This approach will help you make a plan and will enable you to begin the fitting process as soon as your surgeon releases you. If you are not able to take this approach, beginning the discussion about your prosthetic needs and goals at any point gets you that much closer to walking again. If you are already a prosthetic wearer and are in need of a new prosthesis and/or prosthetic clinic, contact us so we can welcome you into our prosthetic family!

Prosthesis Design Factors

Regardless of the level of amputation, there are many factors taken into account when designing a prosthesis. Below are some of these, as well as some of the options available for each component:

• Socket Design — The specific design of the socket is dependent on the condition of the limb/skin/bones, but in general we strive to apply even pressure throughout the entire surface of the limb while utilizing/capturing the bony structure to provide stabilization and control.
• Socket Interface — What is the condition of your skin and what will be worn against your skin to protect you from shear forces/pressures?
  • Silicone (or other types of gel) liner of “cushion” or “locking” design
  • Foam/Pelite liner
  • Prosthetic socks
  • Nothing — just skin against the prosthesis (a flexible inner socket is used in this case)
• Suspension of the Prosthesis — How will it be held on your body?
  • Suction Suspension — A below the knee prosthesis suction suspension usually utilizes a silicone cushion liner to protect the skin and a sealing sleeve to create a suction between the prosthesis and your limb.
  • Shuttle Lock Suspension — This system uses a silicone locking liner and a locking mechanism built into the prosthesis. The locking liner has a “pin” connected to the end, which is inserted into the shuttle lock mechanism, creating a secure connection between the liner and prosthesis.
  • Elevated Vacuum — This involves a vacuum mechanism that can be mechanical in design or electrical, depending on the individual case. Elevated vacuum applies a vacuum to the entire remaining limb, which provides a very secure suspension, as well as providing other health benefits. Some of these are increased circulation throughout the limb, decreased friction and better control of the prosthesis.
  • These suspension types can be assisted by additional belts or sleeves for either daily use or use during special activities.
• Type of Prosthetic Foot — Feet are designed for different functions/environments, making some feet better for specific activities. Unfortunately, insurance will only cover one foot for your prosthesis. Therefore, we discuss your goals, home and work environment, insurance requirements and other factors prior to selecting a foot. Below are some of the foot design categories:
  • Flexible Keel Foot — Provides limited motion which simulates the movement of the anatomical foot. This foot is designed for someone who walks a moderate amount and is not designed to withstand high activity level.
  • Dynamic Response/Carbon Graphite Foot — This foot reduces the energy required to walk and also provides motion that simulates movement of the anatomical foot and is designed to withstand high activity levels.
  • Activity-Specific Foot — Running blade, water foot, rotator for golf (see below).
  • Microprocessor Foot — This type has several axes of movement in the foot, which are controlled by an onboard computer. The computer reacts to real-time motion, raising or lowering the front of the foot when needed, as well as other calculations. This type of foot is not covered by all insurances.
• Prosthetic Ankle or Shank Adaptor — In some situations, additional movement in the foot/ankle area is beneficial. Some options are as follows:
  • Hydraulic Ankle — Provides about 10-15 degrees of motion through control of hydraulic chambers within the foot/ankle. The addition of an ankle can increase stability while walking on inclines/declines and uneven terrain.
  • Shock and/or Rotation Mechanisms — Parts that provide shock absorption and/or allow rotation of the shank are indicated for some activities. 
  • Note: Insurance companies have specific policies regarding what type of foot can be used in the design of a person's prosthesis. This is usually determined by the current activity level, goals/potential for higher activity and overall health of the individual. We always discuss your insurance policy rules with you when helping design your prosthesis.
• Type of Prosthetic Knee — There are various levels of function offered by different knees. The most appropriate knee is chosen by determining your physical capabilities and the activities you will be performing. Some of the options are below:
  • Mechanical Knee with Safety Features — Designed for someone who will likely use the prosthesis in the home and the community while using a walker.
  • Mechanical Hydraulic Knee — Designed for people who are independent walkers (do not use a walker), those who often walk on uneven ground and who walk at different speeds.
  • Microprocessor-Controlled Knee — Often referred to as “bionic”. There are several different categories of computerized knees, which assist in differing ways. They all involve an onboard computer that controls the hydraulic fluid, and in some cases motors, to provide superior stability and mobility. Insurance companies have specific rules concerning microprocessor-controlled knees. We are here to help determine if you are a candidate for a computerized knee and to help you understand what is covered by your policy.

We’re your trusted guide throughout this entire process. If you’re ready to get started or if you have any questions, don’t hesitate to reach out to us.

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