Lower Limb Prosthetic Introduction

Physiotherapy and Prosthetics

The Physiotherapist spends many hours with the patient with limb loss during the rehabilitation phase.  For the patient’s best interest the physiotherapist and prosthetist should work closely together.  Therapists are urged to obtain the manufacturer's information regarding the prosthetic components of the patient that is treated. [1]

The Physiotherapist is not required to understand all the technical aspects of the prosthesis and fitting but should have a knowledge of the following: [1]

  1. Proper prosthetic fit and alignment - this will enable the therapist to to evaluate if the cause for gait deviation and pain is as a result of the prosthesis. [2]
  2. Function of the different prosthetic components - to be able to teach the patient to use the prosthesis optimally and to apply the correct gait training strategy  (see for e.g. different types of knees), and avoid pitfalls (for e.g. loading the prosthetic toe might unlock a specific knee joint). [2]
  3. Correct donning of the prosthesis and what to do if the socket sits uncomfortably. [2]

Prosthetic Prescription

Prescription of a prosthetic is a multidisciplinary process that includes at least the user, prosthetist and physiotherapist. During the prescription process the team decides on the type of device that should be fabricated and also the socket design, the various types of components and the choice of suspension. All these decisions are very important for the rehabilitation process that will happen later.

Fabrication of the Prosthesis

The fabrication of the prescribed prosthesis also goes through various stages that could influence considerably the rehabilitation and the physiotherapy program planned after the first fitting.

These fabrication steps are:

  1. Casting
  2. Positive mould
  3. Rectification
  4. Assembling
  5. Alignments
  6. Cosmetic

Prosthetic Components

Replacing the movements of the human body with prosthetic components is a very complex and complicated task. Prosthetic components can imitate, with different level of complexity, these movements but never replace them. Obviously, the higher the level of imitation, the higher is its complexity and price.

With loss of sensory and proprioception, the amputee must rely solely on sensory capabilities of his stump and body, which may affect confidence during the execution of the march.

However, modern prosthetic technologies offer wide range of components, especially in lower limb prosthesis, which manage to replace the major movements and enable users to perform the gait.

Below, we add some examples of common prosthetic components and correlation between the prosthetic design and the gait.

[3]

The following components form part of a prosthetic fit:

  1. The Socket
  2. Suspension
  3. Knee Joint
  4. Foot
  5. Other components: pylon, off sets, adapters etc.
[4]

The Assembling / Alignment

Once the socket fits comfortably, the foot, knee (if necessary) and other components are then attached to the socket (Assembling). The alignment process starts in order to insure appropriate function and respect of biomechanical structure of the body (Alignment).

As the socket fit, a proper alignment and biomechanical adjustment of the prosthesis to the user is crucial and needs time and expertise in order to provide the best functional outcome for the user.

Initial “Bench” Alignment,

Done on the bench without the user. The alignment parameters depend on the socket design, the types of components used and the style of shoe (the height of the heel is very important). It follows technical instructions provided with the technology selected. The use of an alignment jig is highly recommended in order to attach the socket to the rest of the prosthetic leg at the optimal place.

Watch the following presentations to learn more about transfemoral and transtibial initial alignment (use the pause button to examine each slide)

Static Alignment

Done during the first fitting session with the user and a multidisciplinary medical team. This alignment is done in sitting and in standing position while patient is placing weight on the prosthesis. The aim of the static alignment process is to make all necessary corrections in height, inclination and translation to adjust the prosthesis to the specific biomechanical profile of the user before the first step.

Watch the following presentations to learn more about transfemoral and transtibial static alignment (use the pause button to examine each slide)

Dynamic Alignment

Done within gait training and while the user is walking. The dynamic alignment is implementation with a particular user of the generic gait deviations analysis.

Watch the transtibial dynamic alignment presentation (use the pause button to examine each slide)


The Cosmetic

When the socket and the alignments are fine, and when the user reaches the end of his rehabilitation program and can successfully do all exercises and activities proposed in the treatment plan, the multidisciplinary team can decide to finish the prosthesis. That generally means to fix all adjustments of the device and make the cosmetic. The cosmetic may be very different depending on user’s tastes and needs. A sportive kid may like a prosthesis with bright colors. A lady may prefer a texture and color that best imitates their real leg to be able to wear dresses. And a farmer working in a wet environment would choose a plastic waterproof cosmetic.

The choice of cosmetic, as the choice of components and technology, will also depend on the financial resources and the level of medical coverage allocated to the fabrication of the device. Prices are very different and is a factor to take in consideration.


Possibilities with Technology

[8]

References

  1. 1.0 1.1 Engstrom B, Van de Ven C, editors. Therapy for amputees. Elsevier Health Sciences; 1999.
  2. 2.0 2.1 2.2 Prosthetics. AustPar. Australian Physiotherapists in Amputee Rehabilitation. Available from: http://www.austpar.com/portals/prosthetics/prosthetics.php [Accessed 28 Dec 2017]
  3. Parts of Your Prosthesis. Available from: limb-loss.org https://youtu.be/_C976jbNgYk [Accessed 01/01/2018]
  4. AmputeeOT: How An Above Knee (AK) Prosthetic Leg Works Available from: https://youtu.be/ZCUAnH3epRQ
  5. Physiopedia. A introduction to the new Physiopedia Plus. Available from: http://www.youtube.com/watch?v=zk03HCIeEiI[last accessed 30/10/17]
  6. MOOR Ortotika in Protetika / MOOR Orthotics & Prosthetics. Above knee amputee cosmesis. Available from: https://youtu.be/XkEjF3EG7wQ
  7. The London Prosthetic Centre. Silicone Cosmesis. Available from: https://youtu.be/JzWZerGZr_c
  8. TED. New bionics let us run, climb and dance | Hugh Herr. Available from: https://youtu.be/CDsNZJTWw0w