Abstract: A bone resection guide positioning apparatus includes: a fixing part including a medullary rod configured to be inserted into a femur, a base configured to be disposed in proximity to a distal end of the femur, and a supporting pillar detachably connected to the base; a measuring part including a first connection portion connected to the supporting pillar and an indicator coupled to the first connection portion, the indicator being configured to indicate a valgus angle formed by a femoral functional axis and a femoral anatomical axis based on a positional relationship between the indicator and a femoral head center, the femoral functional axis connecting the femoral head center and a knee joint center; and a guide support including a second connection portion connected to the base and a support body connected to the second connection portion, to which support body a bone resection guide is detachably mounted.

Abstract: An arm structure includes: a pair of arms; a support post; a support member; a cam provided in one of the pair of arms; a shaft member inserted through a lateral insertion hole of the support member; and a pair of ring-shaped members provided in end portions of the shaft member, wherein by turning the one of the arms around its axis thereby to make the cam revolve, a force works to make the shaft member move, and due to its reaction force the ring-shaped members pressure-contact the support member and a slit portion is narrowed. As a result, a longitudinal insertion hole is diameter-reduced and becomes in a state of pressure-contacting the support post, leading to restriction of rotation of the arm around the support post, and the cam pressure contacts the one of the arms, leading to restriction of sliding of the arm in a long side direction, and the ring-shaped members pressure-contact the support member, leading to restriction of rotation of the arm by the shaft member.