Prosthetic foot

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A foot prosthesis is necessary if normal shoes (ready-made shoes) are no longer wearable or walking is difficult or impossible due to an amputation on the foot . Cosmetic deficits can also be compensated.

Causes and goal of prosthetic fitting

The following causes are possible for amputations:

  1. Trauma, e.g. B. an accident
  2. Arterial occlusive disease, diabetes mellitus
  3. Tumors
  4. congenital malformations
  5. various rare diseases

The primary goal is to restore and maintain the patient's ability to walk over the long term .

Problem

There are problems with the scars that occur during amputation. Here it depends very much on the skill of the surgeon not to place the scars on the sole of the foot. The shape of the stump end is also important; the skeleton should be modeled very smoothly, as prominent bones always lead to pressure points. So here the shape takes precedence over maintaining the length, since the stump end must primarily be able to withstand loads.

With shorter foot stumps there are problems with pressure distribution. The end of the stump is exposed to the same forces as the healthy foot, only these are distributed over a much smaller area. The biomechanical lever ratios also change: by shortening the foot lever, the rolling behavior changes, etc. a. the stride length is shortened.

The strong calf muscles that bend the foot down now have less resistance with the shorter lever and therefore pull the foot down into the so-called equinus position. In addition, very short stumps tend to supinate, i. H. the foot tips outwards.

Aspects of orthopedic care

Different amputation lines, starting in the toe area to the rear foot, lead to fundamentally different stress situations. The more the foot is shortened, the more resilience and stability are restricted.

The main components of the restoration are the bedding of the stump end, the restoration of the mechanical foot length through a partially elastic sole stiffening and the resulting distribution of the ground force on the heel and lower leg.

The shorter the foot, the greater the power to transfer the ground force to the lower leg. It must be taken into account how heavy the load on the supply will be by the patient, the higher the load, the higher the supply on the lower leg must go up. A heavy load arises e.g. B. through physical work or high body weight.

Forms of care

If the feet are barely shortened, such as amputation of the big toe or all toes, a fitting of the ready-to-wear shoe with sole stiffening and toe replacement is sufficient. Custom-made silicone prostheses that have a predominantly cosmetic effect (e.g. in sandals) are also possible.

For shorter foot stumps, the spectrum ranges from the orthosis in a ready-to-wear shoe to the orthopedic made-to-measure shoe with an integrated stump bedding and the support strap pulled up on the lower leg. In doing so, there must always be a distinction between the patient's cosmetic wishes, ensuring the function of the supply and the area of ​​application, i.e. H. be weighed against the burden.

With low load z. B. as a house shoe, depending on the length of the stump, a half-shoe-high supply can be dared. In this case, a strong tension strap must be integrated around the heel bone in order to exclude any heel play and to transfer the ground force to the heel and thus also the lower leg.

Care of the diabetic stump

Special measures must be taken in the case of amputations due to diabetic foot syndrome or similar disorders of blood circulation or innervation of the lower extremities. In this context, the skin often reacts extremely sensitively to pressure, friction and injuries, although some of the patients feel nothing of this because their nerves no longer function normally.

The supply of such foot stumps is very complicated and expensive, since the smaller load area is also extremely stressed here. In connection with extremely precise fitting, the cooperation of the patient is of the utmost importance. For example, in the beginning the most important thing is that the patient does not take off the shoes or orthosis and walk barefoot, as he can inflict new injuries so quickly.

The patient has to have his feet checked regularly for changes or injuries.

In addition, the patient should not be tempted by their limited pain perception to put weight on the affected foot as before in the months after the amputation. In most cases, this would damage the skin, which in turn can lead to severe infections, which means that new amputations are in sight.

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  • Expertise in orthopedic shoe technology , Kraus, 1986
  • Orthopedic care of the foot , Baumgartner and Stinus, 1995
  • Orthopedic technology , Hohmann and Uhlig, 2004
  • The Diabetic Foot , Bischof et al., 2000