Total internal big toe joint prosthesis - has cap flattened towards sesamoid bones

摘要

The total internal prosthesis replaces the base joint of the big toe, comprising a cap forming a convex joint face fitting on the head of the middle foot, and a slightly convex mating plate anchored to the proximal end of the big toe base member. The cap is flattened towards the sesamoid bones, the flat being typically formed as far as 30 deg. from the centre line. Behind the flat the surface can merge into a circular portion, both on outside and inside, and the concavity of the mating plate can be less than 60 deg.