Disclosed are systems and methods for assisting with procedures involving a subject's joint, such as a joint. Robotic devices move and position the subject to manipulate the joint and sensing devices sense the joint gap. The robotic devices are controlled based on the joint gap. Novel techniques are disclosed for joint gap segmentation, approximating an uncertainty in determination of the varying dimension of the joint gap, and real-time motion analysis of the joint gap size. In some examples, a kinematic model of the patient's anatomy is utilized to provide robotically assisted manipulation of the same using the techniques described herein.