Surgical instrument and positioning method

A surgical instrument for use with an anatomical structure, said instrument comprising:

• an anchoring member having a first portion securable to the anatomical structure;
• an implement portion, said implement portion being selectively translatably adjustable and selectively rotatably adjustable relative to said anchoring member;
• and
• at least one reference element registerable in a computer implemented image guidance system wherein said at least one reference element is moved relative to said anchoring member by movement of said implement portion relative to said anchoring member;
• wherein said implement portion is selectively translatable along three substantially mutually perpendicular translational axes and said implement portion is selectively rotatable about three substantially mutually perpendicular rotational axes.

A surgical instrument for resecting a tibia, said instrument comprising:

• a fastener selectively secured to the tibia;
• a resection guide, said resection guide being selectively translatable relative to said fastener and selectively rotatable relative to said fastener;
• and
• at least one reference element registerable in a computer implemented image guidance system, said at least one reference element mounted in a predetermined orientation relative to said resection guide.