Sach (solid ankle, cushioned heel)

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- Discussion:
    - has been standard for decades, and is still appropriate for general
          use, however, the multiaxis foot and energy storing foot are
          becoming more popular;
    - w/ BKA prosthesis if Sach foot heel cushion is too soft knee will be
          hyperextending during stance phase;
    - AKA prosthesis which has its Sach foot attached too far posterior
          on the shin, will cause the knee to buckle at heel strike;