The proximal interphalangeal (PIP) joint of the finger are formed by the articulation between the proximal phalanges head (PPH) and the middle phalanges base (MPB). The PPH has two rounded condyles, separated by a shallow central groove. The opposing surface of the MPB has two shallow concave facets separated by a central ridge. Determination of distribution of joint contact and joint motion are necessary to understanding the progression of joint deterioration and to the design of appropriate implants for finger joint arthroplasty. Traditionally, such data have been obtained from in vitro study of cadaveric specimens. Magnetic resonance imaging (MRI) has recently been shown to be a valid method of quantifying the joint contact area, indicating the potential for in vivo assessment. In the present study, we adapted an MRI system to study the three-dimensional in vivo articular cartilage contact areas and contact distributions of the PIP joint of the index finger on adopting three flexion angles.