A trial intervertebral disk implant includes a first plate, a second plate, adjacent to the first plate, a conformable layer between the first and the second plates, and a pressure sensor within the conformable layer. The pressure sensor measures a distribution of compression force exerted by the first and the second plates on the conformable layer. The trial implant includes indicating means for indicating a position of the first and the second plates relative to each other, and locating means, for locating a position of the trial implant relative to the vertebrae between which said trial implant has been placed. The trial implant further includes at least one retractable member, connected to at least one of the first and the second plates. The retractable member can be extended or retracted through an aperture defined by a surface of the plate that is proximal to an abutting vertebra.