Recent technological advances in robotic sensing and actuation methods have prompted
development of a range of new medical training simulators with multiple feedback modalities. Learning to
interpret facial expressions of a patient during medical examinations or procedures has been one of the key
focus areas in medical training. This article reviews facial expression rendering systems in medical training
simulators that have been reported to date. Facial expression rendering approaches in other domains are also
summarized to incorporate the knowledge from those works into developing systems for medical training
simulators. Classifications and comparisons of medical training simulators with facial expression rendering
are presented, and important design features, merits and limitations are outlined. Medical educators,
students and developers are identified as the three key stakeholders involved with these systems and their
considerations and needs are presented. Physical-virtual (hybrid) approaches provide multimodal feedback,
present accurate facial expression rendering, and can simulate patients of different age, gender and ethnicity
group; makes it more versatile than virtual and physical systems. The overall findings of this review and
proposed future directions are beneficial to researchers interested in initiating or developing such facial
expression rendering systems in medical training simulators.