In leg amputation the remained bone is rasped to make the edges smoother to avoid tissue injuries. but still there is an unusual structure underneath the skin.
Why don’t we use an implantable structure to avoid abnormal structure like sharp edges and damp the undue pressure and shocks underneath bones, the same way heel fat pad*(HFP) protects the underlying structures in the heel?
From my point of view, using such implants might also ease the use of prosthetic legs and decrease the possible pain in leg- prosthetic interfaces.
Are there any specific reasons not to use such implants during the leg amputation?
*The heel fat pad (HFP) is a highly specialized adipose-based structure that protects the rear foot and the lower extremities from the stress generated during the heel-strike and the initial support phase of locomotion. HFP cushioning efficiency is the result of its structure, shape and thickness.
In children is difficult to avoid sharp edges because the remaining bone grow quickly than soft tissue. All amputation made before 10 years old (sometimes in older children also) need secondary correction. I have any experience in adults amputation.
In children, osteochondral plug derived from bone from epiphyseal amputated part may be used and held with K wires or press fit in order to check future growth as described in literature. If we make our cuts in bevelled fashion then the prominence is lesser and myoplasty may supplant additional cushioning. However all these things are dependent on pattern of injury or level of amputation and the final ball lies in surgeon's court.
I think that is a very good idea. A plastic cap over the cut bone would reduce the risk of skin erosion, especially in patients with malnutrition. Sterility would be a very important consideration.
I believe that rasping is adequate but the real thing that matters is the designing the thick muscle flap that must cover the amputation site.
It is presumed that this discussion is about standard length stump of below knee amputation.
If the bone ends are adequately bevelled accompanied by a proper myodesis/myoplasty, there is adequate cushioning in most cases. In most modern prosthesis, weight transmission is not through the stump end but through a PTB or suction socket, so the stump end cushioning is not really that important. If bone ends are troublesome, revision of stump would be a better way to manage it than an implanted prosthesis.
An implanted prosthesis is a way of making a simple thing very complex. All such prosthesis would still need muscle cover, creating a further challenge in an already compromised soft tissue envelope. And if one implants a silicon/similar soft prosthesis, one may need to go back to older pattern of prosthetics where weight transmission is through stump end. Why re-invent the wheel?
In addition, this prosthesis would wear faster being apposed to bone ends on one side and subjected to body weight loading as well as frictional forces on the other side.
Bevelled bone end + adequate thickness of myoplasty should do the trick. Implant on the bone end is not necessary especially if the prosthesis is not designed to receive weight transmission through the end stump. If we worry about bad soft tissue surrounding the bone end, putting an implant on that area will create more problems, such as rapid implant wear, infections. Higher amputation level with good soft tissue should be put into consideration.
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