PROBLEM TO BE SOLVED: To provide an artificial knee joint whose amount and rate of roll-back are small in shallow bending and large in deep bending.SOLUTION: The artificial knee joint includes: a femoral component 20 including a medial condyle 21, a lateral condyle 22, a first sliding surface 24 posteriorly connected leaving an opening 23 between the medial condyle 21 and lateral condyle 22, and a second sliding surface 25 above the first sliding surface 24 and a tibia plate 30 including a medial fossa 31, a lateral fossa 32, a post part 36 projecting upward from between the medial fossa 31 and lateral fossa 32 and inserted into the opening 23, a third sliding surface 34 with which the first sliding surface 24 comes in contact on the posterior surface of the post part 36, and a fourth sliding surface 35 with which the second sliding surface 25 comes in contact at a location posterior to the post part 36. The first and fourth sliding surfaces 24, 35 are convex curved surfaces, and the fourth sliding surface 35 is posterior to the third sliding surface 34. According to a bending angle, the artificial knee joint is in either a first sliding state where the first and third sliding surfaces 24, 34 contact each other, and a second sliding state where the second and fourth sliding surfaces 25, 35 contact each other.COPYRIGHT: (C)2012,JPO&INPIT【課題】ロールバック量及びロールバック率が、浅屈曲で小さく、深屈曲で大きい人工膝関節を提供する。【解決手段】本発明の人工膝関節では、大腿骨コンポーネント20が、内側顆21、外側顆22、内側顆21と外側顆22と間に開口部23を残して後端接続する第1の摺動面24、及び第1の摺動面24上方の第2の摺動面25を備え、脛骨プレート30が、内側窩31、外側窩32、内側窩31と外側窩32との間から上方に突出して開口部23に挿入されるポスト部36、ポスト部36後面に第1の摺動面24が接触する第3の摺動面34、及びポスト部36後方に第2の摺動面25が接触する第4の摺動面35を備える。第1、第4の摺動面24、35は凸状曲面で、第4の摺動面35は第3の摺動面34より後方で、屈曲角度に応じて、第1、第3の摺動面24、34が接触する第1の摺動状態と、第2、第4の摺動面25、35が接触する第2の摺動状態とを有する。【選択図】図2
