Fig. 8From: Novel implant design of the proximal interphalangeal joint using an optimized rolling contact joint mechanismThe position of the average centers of rotation (ACRs) in all participants around the geometric center of the proximal phalangeal head (CPH). The black dots and red “x” marks represent the ACRs of the middle and proximal phalanges, respectively. All ACRs tended to be located inferior to the geometric center of the proximal phalangeal headBack to article page