Introduction to below knee prosthetics

below knee prosthetics

An amputation, especially at any level below the knee, does not usually present a particularly disabling condition. With the use of modern below knee prosthetics and treatment methods, below knee amputees who are free from complicating medical problems can do most of the things they could do prior to amputation.

Studies suggest that there are 1.5 amputees per 1000 persons. Therefore, the current number of amputees in South Africa amounts to approximately 60 000.

Below Knee Prosthetic requirements

In order for a patient to be able to wear a below knee prosthesis, at least 40% of the following criteria should be met so as to obtain a positive outcome.

  • The residual limb (stump) should be well-formed and round at the distal end.
  • The residual limb (stump) should be well healed with no open wounds.
  • Good muscle tone should be evident
  • No swelling should be evident
  • There should be full movement of the hip and knee.
  • Weight should not exceed 10kgs beyond normal weight.
  • The ability to walk on crutches and achieve good balance is essential.
  • The residual limb (stump) should be able to sufficiently carry body weight.
  • Patients should display high levels of motivation.
  • The prosthetic should be affordable to the patient.

There are more below knee (trans tibial) amputees than any other type. Surgeons preserve the knee joint whenever it is possible and practical to do so and attempt to fashion the residual limb (stump) at the lowest practical level. Very short below knee stumps make fitting extremely difficult whereas very long below knee stumps limit the choice of prosthetic feet.

Harmony® system

The Harmony® system controls the volume of the residual limb and prevents volume fluctuations. As opposed to a specific weight bearing socket, a total surface weight bearing socket is used.

At a glance, the Harmony® system:

  • Monitors residual limb volume
  • Improves proprioception
  • Enhances blood circulation to the residual limb
  • Ensures an excellent fit
  • Relieves strain on the joints and spinal column

The Harmony® system creates an elevated vacuum environment between the socket and the liner. Using the patented Harmony® pump, each step removes air from the socket to enable a precise socket fit at all times. The superior fit helps prevent residual limb/socket pseudo arthrosis and improves proprioception.

The Harmony® system helps prevent fluctuations in volume

The Harmony® system’s elevated vacuum helps regulate volume changes in the residual limb to achieve a consistent fit at all times. In using a total surface weight bearing socket, pressure is relieved on load-bearing areas. Beyond pulling air from the socket, the pump also provides shock absorption and rotation.

The Harmony® system consists of a pump, polyurethane liner and gel-coated sleeve.