High-tech development within prosthetics for lower limb amputees can benefit from high-tech methods to study the socket fit. Roentgen stereophotogrammetry is one such method with high resolution to study stability with point motion and segment motion simultaneously to show how well bonded the socket is to the stump. It has been used to follow results of total joint replacement concerning loosening and wear of components. In this study, one transtibial amputee was examined with tantalum bone markers implanted through skin and also glued into the hard socket. Four different prosthetic suspensions were used, and we simulated four different gait cycle positions and recorded the micromotions between the tibial bone segment and the hard socket three-dimensionally. The vertical motion varied 10 to 30 mm and the AP motion 0 to 15 mm. For the first time, we could measure rotation of the socket on the stump about a vertical axis. The rotation in the transversal plane was 7.5 outward. Airtight sleeve with expulsion valve gave the best stability.