What are the technical considerations of weight transfer in lower-extremity amputations?

Updated: Apr 29, 2021
  • Author: Janos P Ertl, MD; Chief Editor: Vinod K Panchbhavi, MD, FACS, FAOA, FABOS, FAAOS  more...
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Answer

For the patient to effectively transfer weight from the residual limb to the prosthesis, an intact soft-tissue envelope is required, as described above. Load transfer is accomplished through direct means, indirect means, or both. Direct weight transfer implies that the residual limb is capable of end weightbearing within a prosthesis. End weightbearing is easily accomplished through disarticulations at the ankle (Symes-level amputation) and knee levels. The proximal articulation of the joint is maintained, functions normally, and is broad enough to distribute the end-bearing forces.

Although joint amputations maintain length and muscle attachments, patients often have a difficult time with prosthetic fitting. The issues after knee disarticulations include that in which the more distal center of knee rotation makes sitting in cars and closed areas difficult. The knee protrudes farther than the contralateral knee, and the lower leg is much shorter. For ankle disarticulations, patients report that the prostheses are too bulky.

Indirect weight transfer implies distributing load to a more proximal bony area and incorporating a total-contact interface with the soft tissues of the extremity. In the past, with transdiaphyseal amputations, an indirect weight transfer prosthesis has been used because of the small bone diameter, which is believed to be ineffective in applied load distribution. However, end weightbearing can be accomplished in osteomyoplastic reconstructions in conjunction with a total-contact prosthesis. This reconstruction provides a more durable, pain-free, active, and functional residual extremity. (See Technique.)


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