An additive-manufacturing system for printing spinal implants in-situ, within a patient, is disclosed. The system may include a robotic subsystem having scanning and imaging equipment and an armature including at least one dispensing nozzle and a controller apparatus having a processor and a non-transitory computer-readable medium. The controller may control the scanning and imaging equipment to determine a target alignment of a patients spine, develop an in-situ-printing plan including an in-situ material selection plan based on the target alignment of the patients spine, an interbody access space, and a disc space between adjacent vertebra of the patients spine, and execute the in-situ-printing plan. The controller may further control the armature to dispense at least one material chosen from a rigid material and a pliable material to form at least one motion-sparing implant.