Using facial expressions to assess musculoskeletal pain in older persons.

Past research examined measures of pain among seniors who were experiencing movement-related exacerbations of musculoskeletal pain and obtained clear support for the utility of the behavioural coding of pain-related body movements (e.g., bracing, guarding). Support for the utility of the Facial Action Coding System (FACS), which involves the objective coding of facial reactions, was not as strong. The findings concerning FACS could have been an artifact of the methodology that was used. Specifically, the duration of the facial reactions was not taken into account and the patients suffered from a variety of painful conditions. Thus, the physical activities involved in the study could have been painful for some patients but not for others. The present study corrected these methodological concerns by accounting for the duration of facial reactions and ensuring that all patients suffered from the same painful condition. Participants were 82 post-surgical (knee replacement) inpatients. Cognitive status was assessed using the Modified Mini Mental Status Examination. Under physiotherapist's supervision, the patients performed structured activities (i.e., reclining, standing, knee bends). Facial reactions were coded using FACS. Facial reactions varied as a function of the degree to which the various activities were strenuous. The results support the utility of FACS in the assessment of musculoskeletal pain among seniors undergoing rehabilitation following knee surgery.